/[pcre]/code/trunk/ChangeLog
ViewVC logotype

Diff of /code/trunk/ChangeLog

Parent Directory Parent Directory | Revision Log Revision Log | View Patch Patch

revision 35 by nigel, Sat Feb 24 21:39:05 2007 UTC revision 573 by ph10, Fri Nov 19 19:29:44 2010 UTC
# Line 1  Line 1 
1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
3    
4    Version 8.11 10-Oct-2010
5    ------------------------
6    
7    1.  (*THEN) was not working properly if there were untried alternatives prior
8        to it in the current branch. For example, in ((a|b)(*THEN)(*F)|c..) it
9        backtracked to try for "b" instead of moving to the next alternative branch
10        at the same level (in this case, to look for "c"). The Perl documentation
11        is clear that when (*THEN) is backtracked onto, it goes to the "next
12        alternative in the innermost enclosing group".
13    
14    2.  (*COMMIT) was not overriding (*THEN), as it does in Perl. In a pattern
15        such as   (A(*COMMIT)B(*THEN)C|D)  any failure after matching A should
16        result in overall failure. Similarly, (*COMMIT) now overrides (*PRUNE) and
17        (*SKIP), (*SKIP) overrides (*PRUNE) and (*THEN), and (*PRUNE) overrides
18        (*THEN).
19    
20    3.  If \s appeared in a character class, it removed the VT character from
21        the class, even if it had been included by some previous item, for example
22        in [\x00-\xff\s]. (This was a bug related to the fact that VT is not part
23        of \s, but is part of the POSIX "space" class.)
24    
25    4.  A partial match never returns an empty string (because you can always
26        match an empty string at the end of the subject); however the checking for
27        an empty string was starting at the "start of match" point. This has been
28        changed to the "earliest inspected character" point, because the returned
29        data for a partial match starts at this character. This means that, for
30        example, /(?<=abc)def/ gives a partial match for the subject "abc"
31        (previously it gave "no match").
32    
33    5.  Changes have been made to the way PCRE_PARTIAL_HARD affects the matching
34        of $, \z, \Z, \b, and \B. If the match point is at the end of the string,
35        previously a full match would be given. However, setting PCRE_PARTIAL_HARD
36        has an implication that the given string is incomplete (because a partial
37        match is preferred over a full match). For this reason, these items now
38        give a partial match in this situation. [Aside: previously, the one case
39        /t\b/ matched against "cat" with PCRE_PARTIAL_HARD set did return a partial
40        match rather than a full match, which was wrong by the old rules, but is
41        now correct.]
42    
43    6.  There was a bug in the handling of #-introduced comments, recognized when
44        PCRE_EXTENDED is set, when PCRE_NEWLINE_ANY and PCRE_UTF8 were also set.
45        If a UTF-8 multi-byte character included the byte 0x85 (e.g. +U0445, whose
46        UTF-8 encoding is 0xd1,0x85), this was misinterpreted as a newline when
47        scanning for the end of the comment. (*Character* 0x85 is an "any" newline,
48        but *byte* 0x85 is not, in UTF-8 mode). This bug was present in several
49        places in pcre_compile().
50    
51    7.  Related to (6) above, when pcre_compile() was skipping #-introduced
52        comments when looking ahead for named forward references to subpatterns,
53        the only newline sequence it recognized was NL. It now handles newlines
54        according to the set newline convention.
55    
56    8.  SunOS4 doesn't have strerror() or strtoul(); pcregrep dealt with the
57        former, but used strtoul(), whereas pcretest avoided strtoul() but did not
58        cater for a lack of strerror(). These oversights have been fixed.
59    
60    9.  Added --match-limit and --recursion-limit to pcregrep.
61    
62    10. Added two casts needed to build with Visual Studio when NO_RECURSE is set.
63    
64    11. When the -o option was used, pcregrep was setting a return code of 1, even
65        when matches were found, and --line-buffered was not being honoured.
66    
67    12. Added an optional parentheses number to the -o and --only-matching options
68        of pcregrep.
69    
70    13. Imitating Perl's /g action for multiple matches is tricky when the pattern
71        can match an empty string. The code to do it in pcretest and pcredemo
72        needed fixing:
73    
74        (a) When the newline convention was "crlf", pcretest got it wrong, skipping
75            only one byte after an empty string match just before CRLF (this case
76            just got forgotten; "any" and "anycrlf" were OK).
77    
78        (b) The pcretest code also had a bug, causing it to loop forever in UTF-8
79            mode when an empty string match preceded an ASCII character followed by
80            a non-ASCII character. (The code for advancing by one character rather
81            than one byte was nonsense.)
82    
83        (c) The pcredemo.c sample program did not have any code at all to handle
84            the cases when CRLF is a valid newline sequence.
85    
86    14. Neither pcre_exec() nor pcre_dfa_exec() was checking that the value given
87        as a starting offset was within the subject string. There is now a new
88        error, PCRE_ERROR_BADOFFSET, which is returned if the starting offset is
89        negative or greater than the length of the string. In order to test this,
90        pcretest is extended to allow the setting of negative starting offsets.
91    
92    15. In both pcre_exec() and pcre_dfa_exec() the code for checking that the
93        starting offset points to the beginning of a UTF-8 character was
94        unnecessarily clumsy. I tidied it up.
95    
96    16. Added PCRE_ERROR_SHORTUTF8 to make it possible to distinguish between a
97        bad UTF-8 sequence and one that is incomplete.
98    
99    17. Nobody had reported that the --include_dir option, which was added in
100        release 7.7 should have been called --include-dir (hyphen, not underscore)
101        for compatibility with GNU grep. I have changed it to --include-dir, but
102        left --include_dir as an undocumented synonym, and the same for
103        --exclude-dir, though that is not available in GNU grep, at least as of
104        release 2.5.4.
105    
106    18. At a user's suggestion, the macros GETCHAR and friends (which pick up UTF-8
107        characters from a string of bytes) have been redefined so as not to use
108        loops, in order to improve performance in some environments. At the same
109        time, I abstracted some of the common code into auxiliary macros to save
110        repetition (this should not affect the compiled code).
111    
112    
113    Version 8.10 25-Jun-2010
114    ------------------------
115    
116    1.  Added support for (*MARK:ARG) and for ARG additions to PRUNE, SKIP, and
117        THEN.
118    
119    2.  (*ACCEPT) was not working when inside an atomic group.
120    
121    3.  Inside a character class, \B is treated as a literal by default, but
122        faulted if PCRE_EXTRA is set. This mimics Perl's behaviour (the -w option
123        causes the error). The code is unchanged, but I tidied the documentation.
124    
125    4.  Inside a character class, PCRE always treated \R and \X as literals,
126        whereas Perl faults them if its -w option is set. I have changed PCRE so
127        that it faults them when PCRE_EXTRA is set.
128    
129    5.  Added support for \N, which always matches any character other than
130        newline. (It is the same as "." when PCRE_DOTALL is not set.)
131    
132    6.  When compiling pcregrep with newer versions of gcc which may have
133        FORTIFY_SOURCE set, several warnings "ignoring return value of 'fwrite',
134        declared with attribute warn_unused_result" were given. Just casting the
135        result to (void) does not stop the warnings; a more elaborate fudge is
136        needed. I've used a macro to implement this.
137    
138    7.  Minor change to pcretest.c to avoid a compiler warning.
139    
140    8.  Added four artifical Unicode properties to help with an option to make
141        \s etc use properties (see next item). The new properties are: Xan
142        (alphanumeric), Xsp (Perl space), Xps (POSIX space), and Xwd (word).
143    
144    9.  Added PCRE_UCP to make \b, \d, \s, \w, and certain POSIX character classes
145        use Unicode properties. (*UCP) at the start of a pattern can be used to set
146        this option. Modified pcretest to add /W to test this facility. Added
147        REG_UCP to make it available via the POSIX interface.
148    
149    10. Added --line-buffered to pcregrep.
150    
151    11. In UTF-8 mode, if a pattern that was compiled with PCRE_CASELESS was
152        studied, and the match started with a letter with a code point greater than
153        127 whose first byte was different to the first byte of the other case of
154        the letter, the other case of this starting letter was not recognized
155        (#976).
156    
157    12. If a pattern that was studied started with a repeated Unicode property
158        test, for example, \p{Nd}+, there was the theoretical possibility of
159        setting up an incorrect bitmap of starting bytes, but fortunately it could
160        not have actually happened in practice until change 8 above was made (it
161        added property types that matched character-matching opcodes).
162    
163    13. pcre_study() now recognizes \h, \v, and \R when constructing a bit map of
164        possible starting bytes for non-anchored patterns.
165    
166    14. Extended the "auto-possessify" feature of pcre_compile(). It now recognizes
167        \R, and also a number of cases that involve Unicode properties, both
168        explicit and implicit when PCRE_UCP is set.
169    
170    15. If a repeated Unicode property match (e.g. \p{Lu}*) was used with non-UTF-8
171        input, it could crash or give wrong results if characters with values
172        greater than 0xc0 were present in the subject string. (Detail: it assumed
173        UTF-8 input when processing these items.)
174    
175    16. Added a lot of (int) casts to avoid compiler warnings in systems where
176        size_t is 64-bit (#991).
177    
178    17. Added a check for running out of memory when PCRE is compiled with
179        --disable-stack-for-recursion (#990).
180    
181    18. If the last data line in a file for pcretest does not have a newline on
182        the end, a newline was missing in the output.
183    
184    19. The default pcre_chartables.c file recognizes only ASCII characters (values
185        less than 128) in its various bitmaps. However, there is a facility for
186        generating tables according to the current locale when PCRE is compiled. It
187        turns out that in some environments, 0x85 and 0xa0, which are Unicode space
188        characters, are recognized by isspace() and therefore were getting set in
189        these tables, and indeed these tables seem to approximate to ISO 8859. This
190        caused a problem in UTF-8 mode when pcre_study() was used to create a list
191        of bytes that can start a match. For \s, it was including 0x85 and 0xa0,
192        which of course cannot start UTF-8 characters. I have changed the code so
193        that only real ASCII characters (less than 128) and the correct starting
194        bytes for UTF-8 encodings are set for characters greater than 127 when in
195        UTF-8 mode. (When PCRE_UCP is set - see 9 above - the code is different
196        altogether.)
197    
198    20. Added the /T option to pcretest so as to be able to run tests with non-
199        standard character tables, thus making it possible to include the tests
200        used for 19 above in the standard set of tests.
201    
202    21. A pattern such as (?&t)(?#()(?(DEFINE)(?<t>a)) which has a forward
203        reference to a subpattern the other side of a comment that contains an
204        opening parenthesis caused either an internal compiling error, or a
205        reference to the wrong subpattern.
206    
207    
208    Version 8.02 19-Mar-2010
209    ------------------------
210    
211    1.  The Unicode data tables have been updated to Unicode 5.2.0.
212    
213    2.  Added the option --libs-cpp to pcre-config, but only when C++ support is
214        configured.
215    
216    3.  Updated the licensing terms in the pcregexp.pas file, as agreed with the
217        original author of that file, following a query about its status.
218    
219    4.  On systems that do not have stdint.h (e.g. Solaris), check for and include
220        inttypes.h instead. This fixes a bug that was introduced by change 8.01/8.
221    
222    5.  A pattern such as (?&t)*+(?(DEFINE)(?<t>.)) which has a possessive
223        quantifier applied to a forward-referencing subroutine call, could compile
224        incorrect code or give the error "internal error: previously-checked
225        referenced subpattern not found".
226    
227    6.  Both MS Visual Studio and Symbian OS have problems with initializing
228        variables to point to external functions. For these systems, therefore,
229        pcre_malloc etc. are now initialized to local functions that call the
230        relevant global functions.
231    
232    7.  There were two entries missing in the vectors called coptable and poptable
233        in pcre_dfa_exec.c. This could lead to memory accesses outsize the vectors.
234        I've fixed the data, and added a kludgy way of testing at compile time that
235        the lengths are correct (equal to the number of opcodes).
236    
237    8.  Following on from 7, I added a similar kludge to check the length of the
238        eint vector in pcreposix.c.
239    
240    9.  Error texts for pcre_compile() are held as one long string to avoid too
241        much relocation at load time. To find a text, the string is searched,
242        counting zeros. There was no check for running off the end of the string,
243        which could happen if a new error number was added without updating the
244        string.
245    
246    10. \K gave a compile-time error if it appeared in a lookbehind assersion.
247    
248    11. \K was not working if it appeared in an atomic group or in a group that
249        was called as a "subroutine", or in an assertion. Perl 5.11 documents that
250        \K is "not well defined" if used in an assertion. PCRE now accepts it if
251        the assertion is positive, but not if it is negative.
252    
253    12. Change 11 fortuitously reduced the size of the stack frame used in the
254        "match()" function of pcre_exec.c by one pointer. Forthcoming
255        implementation of support for (*MARK) will need an extra pointer on the
256        stack; I have reserved it now, so that the stack frame size does not
257        decrease.
258    
259    13. A pattern such as (?P<L1>(?P<L2>0)|(?P>L2)(?P>L1)) in which the only other
260        item in branch that calls a recursion is a subroutine call - as in the
261        second branch in the above example - was incorrectly given the compile-
262        time error "recursive call could loop indefinitely" because pcre_compile()
263        was not correctly checking the subroutine for matching a non-empty string.
264    
265    14. The checks for overrunning compiling workspace could trigger after an
266        overrun had occurred. This is a "should never occur" error, but it can be
267        triggered by pathological patterns such as hundreds of nested parentheses.
268        The checks now trigger 100 bytes before the end of the workspace.
269    
270    15. Fix typo in configure.ac: "srtoq" should be "strtoq".
271    
272    
273    Version 8.01 19-Jan-2010
274    ------------------------
275    
276    1.  If a pattern contained a conditional subpattern with only one branch (in
277        particular, this includes all (*DEFINE) patterns), a call to pcre_study()
278        computed the wrong minimum data length (which is of course zero for such
279        subpatterns). This could cause incorrect "no match" results.
280    
281    2.  For patterns such as (?i)a(?-i)b|c where an option setting at the start of
282        the pattern is reset in the first branch, pcre_compile() failed with
283        "internal error: code overflow at offset...". This happened only when
284        the reset was to the original external option setting. (An optimization
285        abstracts leading options settings into an external setting, which was the
286        cause of this.)
287    
288    3.  A pattern such as ^(?!a(*SKIP)b) where a negative assertion contained one
289        of the verbs SKIP, PRUNE, or COMMIT, did not work correctly. When the
290        assertion pattern did not match (meaning that the assertion was true), it
291        was incorrectly treated as false if the SKIP had been reached during the
292        matching. This also applied to assertions used as conditions.
293    
294    4.  If an item that is not supported by pcre_dfa_exec() was encountered in an
295        assertion subpattern, including such a pattern used as a condition,
296        unpredictable results occurred, instead of the error return
297        PCRE_ERROR_DFA_UITEM.
298    
299    5.  The C++ GlobalReplace function was not working like Perl for the special
300        situation when an empty string is matched. It now does the fancy magic
301        stuff that is necessary.
302    
303    6.  In pcre_internal.h, obsolete includes to setjmp.h and stdarg.h have been
304        removed. (These were left over from very, very early versions of PCRE.)
305    
306    7.  Some cosmetic changes to the code to make life easier when compiling it
307        as part of something else:
308    
309        (a) Change DEBUG to PCRE_DEBUG.
310    
311        (b) In pcre_compile(), rename the member of the "branch_chain" structure
312            called "current" as "current_branch", to prevent a collision with the
313            Linux macro when compiled as a kernel module.
314    
315        (c) In pcre_study(), rename the function set_bit() as set_table_bit(), to
316            prevent a collision with the Linux macro when compiled as a kernel
317            module.
318    
319    8.  In pcre_compile() there are some checks for integer overflows that used to
320        cast potentially large values to (double). This has been changed to that
321        when building, a check for int64_t is made, and if it is found, it is used
322        instead, thus avoiding the use of floating point arithmetic. (There is no
323        other use of FP in PCRE.) If int64_t is not found, the fallback is to
324        double.
325    
326    9.  Added two casts to avoid signed/unsigned warnings from VS Studio Express
327        2005 (difference between two addresses compared to an unsigned value).
328    
329    10. Change the standard AC_CHECK_LIB test for libbz2 in configure.ac to a
330        custom one, because of the following reported problem in Windows:
331    
332          - libbz2 uses the Pascal calling convention (WINAPI) for the functions
333              under Win32.
334          - The standard autoconf AC_CHECK_LIB fails to include "bzlib.h",
335              therefore missing the function definition.
336          - The compiler thus generates a "C" signature for the test function.
337          - The linker fails to find the "C" function.
338          - PCRE fails to configure if asked to do so against libbz2.
339    
340    11. When running libtoolize from libtool-2.2.6b as part of autogen.sh, these
341        messages were output:
342    
343          Consider adding `AC_CONFIG_MACRO_DIR([m4])' to configure.ac and
344          rerunning libtoolize, to keep the correct libtool macros in-tree.
345          Consider adding `-I m4' to ACLOCAL_AMFLAGS in Makefile.am.
346    
347        I have done both of these things.
348    
349    12. Although pcre_dfa_exec() does not use nearly as much stack as pcre_exec()
350        most of the time, it *can* run out if it is given a pattern that contains a
351        runaway infinite recursion. I updated the discussion in the pcrestack man
352        page.
353    
354    13. Now that we have gone to the x.xx style of version numbers, the minor
355        version may start with zero. Using 08 or 09 is a bad idea because users
356        might check the value of PCRE_MINOR in their code, and 08 or 09 may be
357        interpreted as invalid octal numbers. I've updated the previous comment in
358        configure.ac, and also added a check that gives an error if 08 or 09 are
359        used.
360    
361    14. Change 8.00/11 was not quite complete: code had been accidentally omitted,
362        causing partial matching to fail when the end of the subject matched \W
363        in a UTF-8 pattern where \W was quantified with a minimum of 3.
364    
365    15. There were some discrepancies between the declarations in pcre_internal.h
366        of _pcre_is_newline(), _pcre_was_newline(), and _pcre_valid_utf8() and
367        their definitions. The declarations used "const uschar *" and the
368        definitions used USPTR. Even though USPTR is normally defined as "const
369        unsigned char *" (and uschar is typedeffed as "unsigned char"), it was
370        reported that: "This difference in casting confuses some C++ compilers, for
371        example, SunCC recognizes above declarations as different functions and
372        generates broken code for hbpcre." I have changed the declarations to use
373        USPTR.
374    
375    16. GNU libtool is named differently on some systems. The autogen.sh script now
376        tries several variants such as glibtoolize (MacOSX) and libtoolize1x
377        (FreeBSD).
378    
379    17. Applied Craig's patch that fixes an HP aCC compile error in pcre 8.00
380        (strtoXX undefined when compiling pcrecpp.cc). The patch contains this
381        comment: "Figure out how to create a longlong from a string: strtoll and
382        equivalent. It's not enough to call AC_CHECK_FUNCS: hpux has a strtoll, for
383        instance, but it only takes 2 args instead of 3!"
384    
385    18. A subtle bug concerned with back references has been fixed by a change of
386        specification, with a corresponding code fix. A pattern such as
387        ^(xa|=?\1a)+$ which contains a back reference inside the group to which it
388        refers, was giving matches when it shouldn't. For example, xa=xaaa would
389        match that pattern. Interestingly, Perl (at least up to 5.11.3) has the
390        same bug. Such groups have to be quantified to be useful, or contained
391        inside another quantified group. (If there's no repetition, the reference
392        can never match.) The problem arises because, having left the group and
393        moved on to the rest of the pattern, a later failure that backtracks into
394        the group uses the captured value from the final iteration of the group
395        rather than the correct earlier one. I have fixed this in PCRE by forcing
396        any group that contains a reference to itself to be an atomic group; that
397        is, there cannot be any backtracking into it once it has completed. This is
398        similar to recursive and subroutine calls.
399    
400    
401    Version 8.00 19-Oct-09
402    ----------------------
403    
404    1.  The table for translating pcre_compile() error codes into POSIX error codes
405        was out-of-date, and there was no check on the pcre_compile() error code
406        being within the table. This could lead to an OK return being given in
407        error.
408    
409    2.  Changed the call to open a subject file in pcregrep from fopen(pathname,
410        "r") to fopen(pathname, "rb"), which fixed a problem with some of the tests
411        in a Windows environment.
412    
413    3.  The pcregrep --count option prints the count for each file even when it is
414        zero, as does GNU grep. However, pcregrep was also printing all files when
415        --files-with-matches was added. Now, when both options are given, it prints
416        counts only for those files that have at least one match. (GNU grep just
417        prints the file name in this circumstance, but including the count seems
418        more useful - otherwise, why use --count?) Also ensured that the
419        combination -clh just lists non-zero counts, with no names.
420    
421    4.  The long form of the pcregrep -F option was incorrectly implemented as
422        --fixed_strings instead of --fixed-strings. This is an incompatible change,
423        but it seems right to fix it, and I didn't think it was worth preserving
424        the old behaviour.
425    
426    5.  The command line items --regex=pattern and --regexp=pattern were not
427        recognized by pcregrep, which required --regex pattern or --regexp pattern
428        (with a space rather than an '='). The man page documented the '=' forms,
429        which are compatible with GNU grep; these now work.
430    
431    6.  No libpcreposix.pc file was created for pkg-config; there was just
432        libpcre.pc and libpcrecpp.pc. The omission has been rectified.
433    
434    7.  Added #ifndef SUPPORT_UCP into the pcre_ucd.c module, to reduce its size
435        when UCP support is not needed, by modifying the Python script that
436        generates it from Unicode data files. This should not matter if the module
437        is correctly used as a library, but I received one complaint about 50K of
438        unwanted data. My guess is that the person linked everything into his
439        program rather than using a library. Anyway, it does no harm.
440    
441    8.  A pattern such as /\x{123}{2,2}+/8 was incorrectly compiled; the trigger
442        was a minimum greater than 1 for a wide character in a possessive
443        repetition. The same bug could also affect patterns like /(\x{ff}{0,2})*/8
444        which had an unlimited repeat of a nested, fixed maximum repeat of a wide
445        character. Chaos in the form of incorrect output or a compiling loop could
446        result.
447    
448    9.  The restrictions on what a pattern can contain when partial matching is
449        requested for pcre_exec() have been removed. All patterns can now be
450        partially matched by this function. In addition, if there are at least two
451        slots in the offset vector, the offset of the earliest inspected character
452        for the match and the offset of the end of the subject are set in them when
453        PCRE_ERROR_PARTIAL is returned.
454    
455    10. Partial matching has been split into two forms: PCRE_PARTIAL_SOFT, which is
456        synonymous with PCRE_PARTIAL, for backwards compatibility, and
457        PCRE_PARTIAL_HARD, which causes a partial match to supersede a full match,
458        and may be more useful for multi-segment matching.
459    
460    11. Partial matching with pcre_exec() is now more intuitive. A partial match
461        used to be given if ever the end of the subject was reached; now it is
462        given only if matching could not proceed because another character was
463        needed. This makes a difference in some odd cases such as Z(*FAIL) with the
464        string "Z", which now yields "no match" instead of "partial match". In the
465        case of pcre_dfa_exec(), "no match" is given if every matching path for the
466        final character ended with (*FAIL).
467    
468    12. Restarting a match using pcre_dfa_exec() after a partial match did not work
469        if the pattern had a "must contain" character that was already found in the
470        earlier partial match, unless partial matching was again requested. For
471        example, with the pattern /dog.(body)?/, the "must contain" character is
472        "g". If the first part-match was for the string "dog", restarting with
473        "sbody" failed. This bug has been fixed.
474    
475    13. The string returned by pcre_dfa_exec() after a partial match has been
476        changed so that it starts at the first inspected character rather than the
477        first character of the match. This makes a difference only if the pattern
478        starts with a lookbehind assertion or \b or \B (\K is not supported by
479        pcre_dfa_exec()). It's an incompatible change, but it makes the two
480        matching functions compatible, and I think it's the right thing to do.
481    
482    14. Added a pcredemo man page, created automatically from the pcredemo.c file,
483        so that the demonstration program is easily available in environments where
484        PCRE has not been installed from source.
485    
486    15. Arranged to add -DPCRE_STATIC to cflags in libpcre.pc, libpcreposix.cp,
487        libpcrecpp.pc and pcre-config when PCRE is not compiled as a shared
488        library.
489    
490    16. Added REG_UNGREEDY to the pcreposix interface, at the request of a user.
491        It maps to PCRE_UNGREEDY. It is not, of course, POSIX-compatible, but it
492        is not the first non-POSIX option to be added. Clearly some people find
493        these options useful.
494    
495    17. If a caller to the POSIX matching function regexec() passes a non-zero
496        value for nmatch with a NULL value for pmatch, the value of
497        nmatch is forced to zero.
498    
499    18. RunGrepTest did not have a test for the availability of the -u option of
500        the diff command, as RunTest does. It now checks in the same way as
501        RunTest, and also checks for the -b option.
502    
503    19. If an odd number of negated classes containing just a single character
504        interposed, within parentheses, between a forward reference to a named
505        subpattern and the definition of the subpattern, compilation crashed with
506        an internal error, complaining that it could not find the referenced
507        subpattern. An example of a crashing pattern is /(?&A)(([^m])(?<A>))/.
508        [The bug was that it was starting one character too far in when skipping
509        over the character class, thus treating the ] as data rather than
510        terminating the class. This meant it could skip too much.]
511    
512    20. Added PCRE_NOTEMPTY_ATSTART in order to be able to correctly implement the
513        /g option in pcretest when the pattern contains \K, which makes it possible
514        to have an empty string match not at the start, even when the pattern is
515        anchored. Updated pcretest and pcredemo to use this option.
516    
517    21. If the maximum number of capturing subpatterns in a recursion was greater
518        than the maximum at the outer level, the higher number was returned, but
519        with unset values at the outer level. The correct (outer level) value is
520        now given.
521    
522    22. If (*ACCEPT) appeared inside capturing parentheses, previous releases of
523        PCRE did not set those parentheses (unlike Perl). I have now found a way to
524        make it do so. The string so far is captured, making this feature
525        compatible with Perl.
526    
527    23. The tests have been re-organized, adding tests 11 and 12, to make it
528        possible to check the Perl 5.10 features against Perl 5.10.
529    
530    24. Perl 5.10 allows subroutine calls in lookbehinds, as long as the subroutine
531        pattern matches a fixed length string. PCRE did not allow this; now it
532        does. Neither allows recursion.
533    
534    25. I finally figured out how to implement a request to provide the minimum
535        length of subject string that was needed in order to match a given pattern.
536        (It was back references and recursion that I had previously got hung up
537        on.) This code has now been added to pcre_study(); it finds a lower bound
538        to the length of subject needed. It is not necessarily the greatest lower
539        bound, but using it to avoid searching strings that are too short does give
540        some useful speed-ups. The value is available to calling programs via
541        pcre_fullinfo().
542    
543    26. While implementing 25, I discovered to my embarrassment that pcretest had
544        not been passing the result of pcre_study() to pcre_dfa_exec(), so the
545        study optimizations had never been tested with that matching function.
546        Oops. What is worse, even when it was passed study data, there was a bug in
547        pcre_dfa_exec() that meant it never actually used it. Double oops. There
548        were also very few tests of studied patterns with pcre_dfa_exec().
549    
550    27. If (?| is used to create subpatterns with duplicate numbers, they are now
551        allowed to have the same name, even if PCRE_DUPNAMES is not set. However,
552        on the other side of the coin, they are no longer allowed to have different
553        names, because these cannot be distinguished in PCRE, and this has caused
554        confusion. (This is a difference from Perl.)
555    
556    28. When duplicate subpattern names are present (necessarily with different
557        numbers, as required by 27 above), and a test is made by name in a
558        conditional pattern, either for a subpattern having been matched, or for
559        recursion in such a pattern, all the associated numbered subpatterns are
560        tested, and the overall condition is true if the condition is true for any
561        one of them. This is the way Perl works, and is also more like the way
562        testing by number works.
563    
564    
565    Version 7.9 11-Apr-09
566    ---------------------
567    
568    1.  When building with support for bzlib/zlib (pcregrep) and/or readline
569        (pcretest), all targets were linked against these libraries. This included
570        libpcre, libpcreposix, and libpcrecpp, even though they do not use these
571        libraries. This caused unwanted dependencies to be created. This problem
572        has been fixed, and now only pcregrep is linked with bzlib/zlib and only
573        pcretest is linked with readline.
574    
575    2.  The "typedef int BOOL" in pcre_internal.h that was included inside the
576        "#ifndef FALSE" condition by an earlier change (probably 7.8/18) has been
577        moved outside it again, because FALSE and TRUE are already defined in AIX,
578        but BOOL is not.
579    
580    3.  The pcre_config() function was treating the PCRE_MATCH_LIMIT and
581        PCRE_MATCH_LIMIT_RECURSION values as ints, when they should be long ints.
582    
583    4.  The pcregrep documentation said spaces were inserted as well as colons (or
584        hyphens) following file names and line numbers when outputting matching
585        lines. This is not true; no spaces are inserted. I have also clarified the
586        wording for the --colour (or --color) option.
587    
588    5.  In pcregrep, when --colour was used with -o, the list of matching strings
589        was not coloured; this is different to GNU grep, so I have changed it to be
590        the same.
591    
592    6.  When --colo(u)r was used in pcregrep, only the first matching substring in
593        each matching line was coloured. Now it goes on to look for further matches
594        of any of the test patterns, which is the same behaviour as GNU grep.
595    
596    7.  A pattern that could match an empty string could cause pcregrep to loop; it
597        doesn't make sense to accept an empty string match in pcregrep, so I have
598        locked it out (using PCRE's PCRE_NOTEMPTY option). By experiment, this
599        seems to be how GNU grep behaves.
600    
601    8.  The pattern (?(?=.*b)b|^) was incorrectly compiled as "match must be at
602        start or after a newline", because the conditional assertion was not being
603        correctly handled. The rule now is that both the assertion and what follows
604        in the first alternative must satisfy the test.
605    
606    9.  If auto-callout was enabled in a pattern with a conditional group whose
607        condition was an assertion, PCRE could crash during matching, both with
608        pcre_exec() and pcre_dfa_exec().
609    
610    10. The PCRE_DOLLAR_ENDONLY option was not working when pcre_dfa_exec() was
611        used for matching.
612    
613    11. Unicode property support in character classes was not working for
614        characters (bytes) greater than 127 when not in UTF-8 mode.
615    
616    12. Added the -M command line option to pcretest.
617    
618    14. Added the non-standard REG_NOTEMPTY option to the POSIX interface.
619    
620    15. Added the PCRE_NO_START_OPTIMIZE match-time option.
621    
622    16. Added comments and documentation about mis-use of no_arg in the C++
623        wrapper.
624    
625    17. Implemented support for UTF-8 encoding in EBCDIC environments, a patch
626        from Martin Jerabek that uses macro names for all relevant character and
627        string constants.
628    
629    18. Added to pcre_internal.h two configuration checks: (a) If both EBCDIC and
630        SUPPORT_UTF8 are set, give an error; (b) If SUPPORT_UCP is set without
631        SUPPORT_UTF8, define SUPPORT_UTF8. The "configure" script handles both of
632        these, but not everybody uses configure.
633    
634    19. A conditional group that had only one branch was not being correctly
635        recognized as an item that could match an empty string. This meant that an
636        enclosing group might also not be so recognized, causing infinite looping
637        (and probably a segfault) for patterns such as ^"((?(?=[a])[^"])|b)*"$
638        with the subject "ab", where knowledge that the repeated group can match
639        nothing is needed in order to break the loop.
640    
641    20. If a pattern that was compiled with callouts was matched using pcre_dfa_
642        exec(), but without supplying a callout function, matching went wrong.
643    
644    21. If PCRE_ERROR_MATCHLIMIT occurred during a recursion, there was a memory
645        leak if the size of the offset vector was greater than 30. When the vector
646        is smaller, the saved offsets during recursion go onto a local stack
647        vector, but for larger vectors malloc() is used. It was failing to free
648        when the recursion yielded PCRE_ERROR_MATCH_LIMIT (or any other "abnormal"
649        error, in fact).
650    
651    22. There was a missing #ifdef SUPPORT_UTF8 round one of the variables in the
652        heapframe that is used only when UTF-8 support is enabled. This caused no
653        problem, but was untidy.
654    
655    23. Steven Van Ingelgem's patch to CMakeLists.txt to change the name
656        CMAKE_BINARY_DIR to PROJECT_BINARY_DIR so that it works when PCRE is
657        included within another project.
658    
659    24. Steven Van Ingelgem's patches to add more options to the CMake support,
660        slightly modified by me:
661    
662          (a) PCRE_BUILD_TESTS can be set OFF not to build the tests, including
663              not building pcregrep.
664    
665          (b) PCRE_BUILD_PCREGREP can be see OFF not to build pcregrep, but only
666              if PCRE_BUILD_TESTS is also set OFF, because the tests use pcregrep.
667    
668    25. Forward references, both numeric and by name, in patterns that made use of
669        duplicate group numbers, could behave incorrectly or give incorrect errors,
670        because when scanning forward to find the reference group, PCRE was not
671        taking into account the duplicate group numbers. A pattern such as
672        ^X(?3)(a)(?|(b)|(q))(Y) is an example.
673    
674    26. Changed a few more instances of "const unsigned char *" to USPTR, making
675        the feature of a custom pointer more persuasive (as requested by a user).
676    
677    27. Wrapped the definitions of fileno and isatty for Windows, which appear in
678        pcretest.c, inside #ifndefs, because it seems they are sometimes already
679        pre-defined.
680    
681    28. Added support for (*UTF8) at the start of a pattern.
682    
683    29. Arrange for flags added by the "release type" setting in CMake to be shown
684        in the configuration summary.
685    
686    
687    Version 7.8 05-Sep-08
688    ---------------------
689    
690    1.  Replaced UCP searching code with optimized version as implemented for Ad
691        Muncher (http://www.admuncher.com/) by Peter Kankowski. This uses a two-
692        stage table and inline lookup instead of a function, giving speed ups of 2
693        to 5 times on some simple patterns that I tested. Permission was given to
694        distribute the MultiStage2.py script that generates the tables (it's not in
695        the tarball, but is in the Subversion repository).
696    
697    2.  Updated the Unicode datatables to Unicode 5.1.0. This adds yet more
698        scripts.
699    
700    3.  Change 12 for 7.7 introduced a bug in pcre_study() when a pattern contained
701        a group with a zero qualifier. The result of the study could be incorrect,
702        or the function might crash, depending on the pattern.
703    
704    4.  Caseless matching was not working for non-ASCII characters in back
705        references. For example, /(\x{de})\1/8i was not matching \x{de}\x{fe}.
706        It now works when Unicode Property Support is available.
707    
708    5.  In pcretest, an escape such as \x{de} in the data was always generating
709        a UTF-8 string, even in non-UTF-8 mode. Now it generates a single byte in
710        non-UTF-8 mode. If the value is greater than 255, it gives a warning about
711        truncation.
712    
713    6.  Minor bugfix in pcrecpp.cc (change "" == ... to NULL == ...).
714    
715    7.  Added two (int) casts to pcregrep when printing the difference of two
716        pointers, in case they are 64-bit values.
717    
718    8.  Added comments about Mac OS X stack usage to the pcrestack man page and to
719        test 2 if it fails.
720    
721    9.  Added PCRE_CALL_CONVENTION just before the names of all exported functions,
722        and a #define of that name to empty if it is not externally set. This is to
723        allow users of MSVC to set it if necessary.
724    
725    10. The PCRE_EXP_DEFN macro which precedes exported functions was missing from
726        the convenience functions in the pcre_get.c source file.
727    
728    11. An option change at the start of a pattern that had top-level alternatives
729        could cause overwriting and/or a crash. This command provoked a crash in
730        some environments:
731    
732          printf "/(?i)[\xc3\xa9\xc3\xbd]|[\xc3\xa9\xc3\xbdA]/8\n" | pcretest
733    
734        This potential security problem was recorded as CVE-2008-2371.
735    
736    12. For a pattern where the match had to start at the beginning or immediately
737        after a newline (e.g /.*anything/ without the DOTALL flag), pcre_exec() and
738        pcre_dfa_exec() could read past the end of the passed subject if there was
739        no match. To help with detecting such bugs (e.g. with valgrind), I modified
740        pcretest so that it places the subject at the end of its malloc-ed buffer.
741    
742    13. The change to pcretest in 12 above threw up a couple more cases when pcre_
743        exec() might read past the end of the data buffer in UTF-8 mode.
744    
745    14. A similar bug to 7.3/2 existed when the PCRE_FIRSTLINE option was set and
746        the data contained the byte 0x85 as part of a UTF-8 character within its
747        first line. This applied both to normal and DFA matching.
748    
749    15. Lazy qualifiers were not working in some cases in UTF-8 mode. For example,
750        /^[^d]*?$/8 failed to match "abc".
751    
752    16. Added a missing copyright notice to pcrecpp_internal.h.
753    
754    17. Make it more clear in the documentation that values returned from
755        pcre_exec() in ovector are byte offsets, not character counts.
756    
757    18. Tidied a few places to stop certain compilers from issuing warnings.
758    
759    19. Updated the Virtual Pascal + BCC files to compile the latest v7.7, as
760        supplied by Stefan Weber. I made a further small update for 7.8 because
761        there is a change of source arrangements: the pcre_searchfuncs.c module is
762        replaced by pcre_ucd.c.
763    
764    
765    Version 7.7 07-May-08
766    ---------------------
767    
768    1.  Applied Craig's patch to sort out a long long problem: "If we can't convert
769        a string to a long long, pretend we don't even have a long long." This is
770        done by checking for the strtoq, strtoll, and _strtoi64 functions.
771    
772    2.  Applied Craig's patch to pcrecpp.cc to restore ABI compatibility with
773        pre-7.6 versions, which defined a global no_arg variable instead of putting
774        it in the RE class. (See also #8 below.)
775    
776    3.  Remove a line of dead code, identified by coverity and reported by Nuno
777        Lopes.
778    
779    4.  Fixed two related pcregrep bugs involving -r with --include or --exclude:
780    
781        (1) The include/exclude patterns were being applied to the whole pathnames
782            of files, instead of just to the final components.
783    
784        (2) If there was more than one level of directory, the subdirectories were
785            skipped unless they satisfied the include/exclude conditions. This is
786            inconsistent with GNU grep (and could even be seen as contrary to the
787            pcregrep specification - which I improved to make it absolutely clear).
788            The action now is always to scan all levels of directory, and just
789            apply the include/exclude patterns to regular files.
790    
791    5.  Added the --include_dir and --exclude_dir patterns to pcregrep, and used
792        --exclude_dir in the tests to avoid scanning .svn directories.
793    
794    6.  Applied Craig's patch to the QuoteMeta function so that it escapes the
795        NUL character as backslash + 0 rather than backslash + NUL, because PCRE
796        doesn't support NULs in patterns.
797    
798    7.  Added some missing "const"s to declarations of static tables in
799        pcre_compile.c and pcre_dfa_exec.c.
800    
801    8.  Applied Craig's patch to pcrecpp.cc to fix a problem in OS X that was
802        caused by fix #2  above. (Subsequently also a second patch to fix the
803        first patch. And a third patch - this was a messy problem.)
804    
805    9.  Applied Craig's patch to remove the use of push_back().
806    
807    10. Applied Alan Lehotsky's patch to add REG_STARTEND support to the POSIX
808        matching function regexec().
809    
810    11. Added support for the Oniguruma syntax \g<name>, \g<n>, \g'name', \g'n',
811        which, however, unlike Perl's \g{...}, are subroutine calls, not back
812        references. PCRE supports relative numbers with this syntax (I don't think
813        Oniguruma does).
814    
815    12. Previously, a group with a zero repeat such as (...){0} was completely
816        omitted from the compiled regex. However, this means that if the group
817        was called as a subroutine from elsewhere in the pattern, things went wrong
818        (an internal error was given). Such groups are now left in the compiled
819        pattern, with a new opcode that causes them to be skipped at execution
820        time.
821    
822    13. Added the PCRE_JAVASCRIPT_COMPAT option. This makes the following changes
823        to the way PCRE behaves:
824    
825        (a) A lone ] character is dis-allowed (Perl treats it as data).
826    
827        (b) A back reference to an unmatched subpattern matches an empty string
828            (Perl fails the current match path).
829    
830        (c) A data ] in a character class must be notated as \] because if the
831            first data character in a class is ], it defines an empty class. (In
832            Perl it is not possible to have an empty class.) The empty class []
833            never matches; it forces failure and is equivalent to (*FAIL) or (?!).
834            The negative empty class [^] matches any one character, independently
835            of the DOTALL setting.
836    
837    14. A pattern such as /(?2)[]a()b](abc)/ which had a forward reference to a
838        non-existent subpattern following a character class starting with ']' and
839        containing () gave an internal compiling error instead of "reference to
840        non-existent subpattern". Fortunately, when the pattern did exist, the
841        compiled code was correct. (When scanning forwards to check for the
842        existencd of the subpattern, it was treating the data ']' as terminating
843        the class, so got the count wrong. When actually compiling, the reference
844        was subsequently set up correctly.)
845    
846    15. The "always fail" assertion (?!) is optimzed to (*FAIL) by pcre_compile;
847        it was being rejected as not supported by pcre_dfa_exec(), even though
848        other assertions are supported. I have made pcre_dfa_exec() support
849        (*FAIL).
850    
851    16. The implementation of 13c above involved the invention of a new opcode,
852        OP_ALLANY, which is like OP_ANY but doesn't check the /s flag. Since /s
853        cannot be changed at match time, I realized I could make a small
854        improvement to matching performance by compiling OP_ALLANY instead of
855        OP_ANY for "." when DOTALL was set, and then removing the runtime tests
856        on the OP_ANY path.
857    
858    17. Compiling pcretest on Windows with readline support failed without the
859        following two fixes: (1) Make the unistd.h include conditional on
860        HAVE_UNISTD_H; (2) #define isatty and fileno as _isatty and _fileno.
861    
862    18. Changed CMakeLists.txt and cmake/FindReadline.cmake to arrange for the
863        ncurses library to be included for pcretest when ReadLine support is
864        requested, but also to allow for it to be overridden. This patch came from
865        Daniel Bergström.
866    
867    19. There was a typo in the file ucpinternal.h where f0_rangeflag was defined
868        as 0x00f00000 instead of 0x00800000. Luckily, this would not have caused
869        any errors with the current Unicode tables. Thanks to Peter Kankowski for
870        spotting this.
871    
872    
873    Version 7.6 28-Jan-08
874    ---------------------
875    
876    1.  A character class containing a very large number of characters with
877        codepoints greater than 255 (in UTF-8 mode, of course) caused a buffer
878        overflow.
879    
880    2.  Patch to cut out the "long long" test in pcrecpp_unittest when
881        HAVE_LONG_LONG is not defined.
882    
883    3.  Applied Christian Ehrlicher's patch to update the CMake build files to
884        bring them up to date and include new features. This patch includes:
885    
886        - Fixed PH's badly added libz and libbz2 support.
887        - Fixed a problem with static linking.
888        - Added pcredemo. [But later removed - see 7 below.]
889        - Fixed dftables problem and added an option.
890        - Added a number of HAVE_XXX tests, including HAVE_WINDOWS_H and
891            HAVE_LONG_LONG.
892        - Added readline support for pcretest.
893        - Added an listing of the option settings after cmake has run.
894    
895    4.  A user submitted a patch to Makefile that makes it easy to create
896        "pcre.dll" under mingw when using Configure/Make. I added stuff to
897        Makefile.am that cause it to include this special target, without
898        affecting anything else. Note that the same mingw target plus all
899        the other distribution libraries and programs are now supported
900        when configuring with CMake (see 6 below) instead of with
901        Configure/Make.
902    
903    5.  Applied Craig's patch that moves no_arg into the RE class in the C++ code.
904        This is an attempt to solve the reported problem "pcrecpp::no_arg is not
905        exported in the Windows port". It has not yet been confirmed that the patch
906        solves the problem, but it does no harm.
907    
908    6.  Applied Sheri's patch to CMakeLists.txt to add NON_STANDARD_LIB_PREFIX and
909        NON_STANDARD_LIB_SUFFIX for dll names built with mingw when configured
910        with CMake, and also correct the comment about stack recursion.
911    
912    7.  Remove the automatic building of pcredemo from the ./configure system and
913        from CMakeLists.txt. The whole idea of pcredemo.c is that it is an example
914        of a program that users should build themselves after PCRE is installed, so
915        building it automatically is not really right. What is more, it gave
916        trouble in some build environments.
917    
918    8.  Further tidies to CMakeLists.txt from Sheri and Christian.
919    
920    
921    Version 7.5 10-Jan-08
922    ---------------------
923    
924    1.  Applied a patch from Craig: "This patch makes it possible to 'ignore'
925        values in parens when parsing an RE using the C++ wrapper."
926    
927    2.  Negative specials like \S did not work in character classes in UTF-8 mode.
928        Characters greater than 255 were excluded from the class instead of being
929        included.
930    
931    3.  The same bug as (2) above applied to negated POSIX classes such as
932        [:^space:].
933    
934    4.  PCRECPP_STATIC was referenced in pcrecpp_internal.h, but nowhere was it
935        defined or documented. It seems to have been a typo for PCRE_STATIC, so
936        I have changed it.
937    
938    5.  The construct (?&) was not diagnosed as a syntax error (it referenced the
939        first named subpattern) and a construct such as (?&a) would reference the
940        first named subpattern whose name started with "a" (in other words, the
941        length check was missing). Both these problems are fixed. "Subpattern name
942        expected" is now given for (?&) (a zero-length name), and this patch also
943        makes it give the same error for \k'' (previously it complained that that
944        was a reference to a non-existent subpattern).
945    
946    6.  The erroneous patterns (?+-a) and (?-+a) give different error messages;
947        this is right because (?- can be followed by option settings as well as by
948        digits. I have, however, made the messages clearer.
949    
950    7.  Patterns such as (?(1)a|b) (a pattern that contains fewer subpatterns
951        than the number used in the conditional) now cause a compile-time error.
952        This is actually not compatible with Perl, which accepts such patterns, but
953        treats the conditional as always being FALSE (as PCRE used to), but it
954        seems to me that giving a diagnostic is better.
955    
956    8.  Change "alphameric" to the more common word "alphanumeric" in comments
957        and messages.
958    
959    9.  Fix two occurrences of "backslash" in comments that should have been
960        "backspace".
961    
962    10. Remove two redundant lines of code that can never be obeyed (their function
963        was moved elsewhere).
964    
965    11. The program that makes PCRE's Unicode character property table had a bug
966        which caused it to generate incorrect table entries for sequences of
967        characters that have the same character type, but are in different scripts.
968        It amalgamated them into a single range, with the script of the first of
969        them. In other words, some characters were in the wrong script. There were
970        thirteen such cases, affecting characters in the following ranges:
971    
972          U+002b0 - U+002c1
973          U+0060c - U+0060d
974          U+0061e - U+00612
975          U+0064b - U+0065e
976          U+0074d - U+0076d
977          U+01800 - U+01805
978          U+01d00 - U+01d77
979          U+01d9b - U+01dbf
980          U+0200b - U+0200f
981          U+030fc - U+030fe
982          U+03260 - U+0327f
983          U+0fb46 - U+0fbb1
984          U+10450 - U+1049d
985    
986    12. The -o option (show only the matching part of a line) for pcregrep was not
987        compatible with GNU grep in that, if there was more than one match in a
988        line, it showed only the first of them. It now behaves in the same way as
989        GNU grep.
990    
991    13. If the -o and -v options were combined for pcregrep, it printed a blank
992        line for every non-matching line. GNU grep prints nothing, and pcregrep now
993        does the same. The return code can be used to tell if there were any
994        non-matching lines.
995    
996    14. Added --file-offsets and --line-offsets to pcregrep.
997    
998    15. The pattern (?=something)(?R) was not being diagnosed as a potentially
999        infinitely looping recursion. The bug was that positive lookaheads were not
1000        being skipped when checking for a possible empty match (negative lookaheads
1001        and both kinds of lookbehind were skipped).
1002    
1003    16. Fixed two typos in the Windows-only code in pcregrep.c, and moved the
1004        inclusion of <windows.h> to before rather than after the definition of
1005        INVALID_FILE_ATTRIBUTES (patch from David Byron).
1006    
1007    17. Specifying a possessive quantifier with a specific limit for a Unicode
1008        character property caused pcre_compile() to compile bad code, which led at
1009        runtime to PCRE_ERROR_INTERNAL (-14). Examples of patterns that caused this
1010        are: /\p{Zl}{2,3}+/8 and /\p{Cc}{2}+/8. It was the possessive "+" that
1011        caused the error; without that there was no problem.
1012    
1013    18. Added --enable-pcregrep-libz and --enable-pcregrep-libbz2.
1014    
1015    19. Added --enable-pcretest-libreadline.
1016    
1017    20. In pcrecpp.cc, the variable 'count' was incremented twice in
1018        RE::GlobalReplace(). As a result, the number of replacements returned was
1019        double what it should be. I removed one of the increments, but Craig sent a
1020        later patch that removed the other one (the right fix) and added unit tests
1021        that check the return values (which was not done before).
1022    
1023    21. Several CMake things:
1024    
1025        (1) Arranged that, when cmake is used on Unix, the libraries end up with
1026            the names libpcre and libpcreposix, not just pcre and pcreposix.
1027    
1028        (2) The above change means that pcretest and pcregrep are now correctly
1029            linked with the newly-built libraries, not previously installed ones.
1030    
1031        (3) Added PCRE_SUPPORT_LIBREADLINE, PCRE_SUPPORT_LIBZ, PCRE_SUPPORT_LIBBZ2.
1032    
1033    22. In UTF-8 mode, with newline set to "any", a pattern such as .*a.*=.b.*
1034        crashed when matching a string such as a\x{2029}b (note that \x{2029} is a
1035        UTF-8 newline character). The key issue is that the pattern starts .*;
1036        this means that the match must be either at the beginning, or after a
1037        newline. The bug was in the code for advancing after a failed match and
1038        checking that the new position followed a newline. It was not taking
1039        account of UTF-8 characters correctly.
1040    
1041    23. PCRE was behaving differently from Perl in the way it recognized POSIX
1042        character classes. PCRE was not treating the sequence [:...:] as a
1043        character class unless the ... were all letters. Perl, however, seems to
1044        allow any characters between [: and :], though of course it rejects as
1045        unknown any "names" that contain non-letters, because all the known class
1046        names consist only of letters. Thus, Perl gives an error for [[:1234:]],
1047        for example, whereas PCRE did not - it did not recognize a POSIX character
1048        class. This seemed a bit dangerous, so the code has been changed to be
1049        closer to Perl. The behaviour is not identical to Perl, because PCRE will
1050        diagnose an unknown class for, for example, [[:l\ower:]] where Perl will
1051        treat it as [[:lower:]]. However, PCRE does now give "unknown" errors where
1052        Perl does, and where it didn't before.
1053    
1054    24. Rewrite so as to remove the single use of %n from pcregrep because in some
1055        Windows environments %n is disabled by default.
1056    
1057    
1058    Version 7.4 21-Sep-07
1059    ---------------------
1060    
1061    1.  Change 7.3/28 was implemented for classes by looking at the bitmap. This
1062        means that a class such as [\s] counted as "explicit reference to CR or
1063        LF". That isn't really right - the whole point of the change was to try to
1064        help when there was an actual mention of one of the two characters. So now
1065        the change happens only if \r or \n (or a literal CR or LF) character is
1066        encountered.
1067    
1068    2.  The 32-bit options word was also used for 6 internal flags, but the numbers
1069        of both had grown to the point where there were only 3 bits left.
1070        Fortunately, there was spare space in the data structure, and so I have
1071        moved the internal flags into a new 16-bit field to free up more option
1072        bits.
1073    
1074    3.  The appearance of (?J) at the start of a pattern set the DUPNAMES option,
1075        but did not set the internal JCHANGED flag - either of these is enough to
1076        control the way the "get" function works - but the PCRE_INFO_JCHANGED
1077        facility is supposed to tell if (?J) was ever used, so now (?J) at the
1078        start sets both bits.
1079    
1080    4.  Added options (at build time, compile time, exec time) to change \R from
1081        matching any Unicode line ending sequence to just matching CR, LF, or CRLF.
1082    
1083    5.  doc/pcresyntax.html was missing from the distribution.
1084    
1085    6.  Put back the definition of PCRE_ERROR_NULLWSLIMIT, for backward
1086        compatibility, even though it is no longer used.
1087    
1088    7.  Added macro for snprintf to pcrecpp_unittest.cc and also for strtoll and
1089        strtoull to pcrecpp.cc to select the available functions in WIN32 when the
1090        windows.h file is present (where different names are used). [This was
1091        reversed later after testing - see 16 below.]
1092    
1093    8.  Changed all #include <config.h> to #include "config.h". There were also
1094        some further <pcre.h> cases that I changed to "pcre.h".
1095    
1096    9.  When pcregrep was used with the --colour option, it missed the line ending
1097        sequence off the lines that it output.
1098    
1099    10. It was pointed out to me that arrays of string pointers cause lots of
1100        relocations when a shared library is dynamically loaded. A technique of
1101        using a single long string with a table of offsets can drastically reduce
1102        these. I have refactored PCRE in four places to do this. The result is
1103        dramatic:
1104    
1105          Originally:                          290
1106          After changing UCP table:            187
1107          After changing error message table:   43
1108          After changing table of "verbs"       36
1109          After changing table of Posix names   22
1110    
1111        Thanks to the folks working on Gregex for glib for this insight.
1112    
1113    11. --disable-stack-for-recursion caused compiling to fail unless -enable-
1114        unicode-properties was also set.
1115    
1116    12. Updated the tests so that they work when \R is defaulted to ANYCRLF.
1117    
1118    13. Added checks for ANY and ANYCRLF to pcrecpp.cc where it previously
1119        checked only for CRLF.
1120    
1121    14. Added casts to pcretest.c to avoid compiler warnings.
1122    
1123    15. Added Craig's patch to various pcrecpp modules to avoid compiler warnings.
1124    
1125    16. Added Craig's patch to remove the WINDOWS_H tests, that were not working,
1126        and instead check for _strtoi64 explicitly, and avoid the use of snprintf()
1127        entirely. This removes changes made in 7 above.
1128    
1129    17. The CMake files have been updated, and there is now more information about
1130        building with CMake in the NON-UNIX-USE document.
1131    
1132    
1133    Version 7.3 28-Aug-07
1134    ---------------------
1135    
1136     1. In the rejigging of the build system that eventually resulted in 7.1, the
1137        line "#include <pcre.h>" was included in pcre_internal.h. The use of angle
1138        brackets there is not right, since it causes compilers to look for an
1139        installed pcre.h, not the version that is in the source that is being
1140        compiled (which of course may be different). I have changed it back to:
1141    
1142          #include "pcre.h"
1143    
1144        I have a vague recollection that the change was concerned with compiling in
1145        different directories, but in the new build system, that is taken care of
1146        by the VPATH setting the Makefile.
1147    
1148     2. The pattern .*$ when run in not-DOTALL UTF-8 mode with newline=any failed
1149        when the subject happened to end in the byte 0x85 (e.g. if the last
1150        character was \x{1ec5}). *Character* 0x85 is one of the "any" newline
1151        characters but of course it shouldn't be taken as a newline when it is part
1152        of another character. The bug was that, for an unlimited repeat of . in
1153        not-DOTALL UTF-8 mode, PCRE was advancing by bytes rather than by
1154        characters when looking for a newline.
1155    
1156     3. A small performance improvement in the DOTALL UTF-8 mode .* case.
1157    
1158     4. Debugging: adjusted the names of opcodes for different kinds of parentheses
1159        in debug output.
1160    
1161     5. Arrange to use "%I64d" instead of "%lld" and "%I64u" instead of "%llu" for
1162        long printing in the pcrecpp unittest when running under MinGW.
1163    
1164     6. ESC_K was left out of the EBCDIC table.
1165    
1166     7. Change 7.0/38 introduced a new limit on the number of nested non-capturing
1167        parentheses; I made it 1000, which seemed large enough. Unfortunately, the
1168        limit also applies to "virtual nesting" when a pattern is recursive, and in
1169        this case 1000 isn't so big. I have been able to remove this limit at the
1170        expense of backing off one optimization in certain circumstances. Normally,
1171        when pcre_exec() would call its internal match() function recursively and
1172        immediately return the result unconditionally, it uses a "tail recursion"
1173        feature to save stack. However, when a subpattern that can match an empty
1174        string has an unlimited repetition quantifier, it no longer makes this
1175        optimization. That gives it a stack frame in which to save the data for
1176        checking that an empty string has been matched. Previously this was taken
1177        from the 1000-entry workspace that had been reserved. So now there is no
1178        explicit limit, but more stack is used.
1179    
1180     8. Applied Daniel's patches to solve problems with the import/export magic
1181        syntax that is required for Windows, and which was going wrong for the
1182        pcreposix and pcrecpp parts of the library. These were overlooked when this
1183        problem was solved for the main library.
1184    
1185     9. There were some crude static tests to avoid integer overflow when computing
1186        the size of patterns that contain repeated groups with explicit upper
1187        limits. As the maximum quantifier is 65535, the maximum group length was
1188        set at 30,000 so that the product of these two numbers did not overflow a
1189        32-bit integer. However, it turns out that people want to use groups that
1190        are longer than 30,000 bytes (though not repeat them that many times).
1191        Change 7.0/17 (the refactoring of the way the pattern size is computed) has
1192        made it possible to implement the integer overflow checks in a much more
1193        dynamic way, which I have now done. The artificial limitation on group
1194        length has been removed - we now have only the limit on the total length of
1195        the compiled pattern, which depends on the LINK_SIZE setting.
1196    
1197    10. Fixed a bug in the documentation for get/copy named substring when
1198        duplicate names are permitted. If none of the named substrings are set, the
1199        functions return PCRE_ERROR_NOSUBSTRING (7); the doc said they returned an
1200        empty string.
1201    
1202    11. Because Perl interprets \Q...\E at a high level, and ignores orphan \E
1203        instances, patterns such as [\Q\E] or [\E] or even [^\E] cause an error,
1204        because the ] is interpreted as the first data character and the
1205        terminating ] is not found. PCRE has been made compatible with Perl in this
1206        regard. Previously, it interpreted [\Q\E] as an empty class, and [\E] could
1207        cause memory overwriting.
1208    
1209    10. Like Perl, PCRE automatically breaks an unlimited repeat after an empty
1210        string has been matched (to stop an infinite loop). It was not recognizing
1211        a conditional subpattern that could match an empty string if that
1212        subpattern was within another subpattern. For example, it looped when
1213        trying to match  (((?(1)X|))*)  but it was OK with  ((?(1)X|)*)  where the
1214        condition was not nested. This bug has been fixed.
1215    
1216    12. A pattern like \X?\d or \P{L}?\d in non-UTF-8 mode could cause a backtrack
1217        past the start of the subject in the presence of bytes with the top bit
1218        set, for example "\x8aBCD".
1219    
1220    13. Added Perl 5.10 experimental backtracking controls (*FAIL), (*F), (*PRUNE),
1221        (*SKIP), (*THEN), (*COMMIT), and (*ACCEPT).
1222    
1223    14. Optimized (?!) to (*FAIL).
1224    
1225    15. Updated the test for a valid UTF-8 string to conform to the later RFC 3629.
1226        This restricts code points to be within the range 0 to 0x10FFFF, excluding
1227        the "low surrogate" sequence 0xD800 to 0xDFFF. Previously, PCRE allowed the
1228        full range 0 to 0x7FFFFFFF, as defined by RFC 2279. Internally, it still
1229        does: it's just the validity check that is more restrictive.
1230    
1231    16. Inserted checks for integer overflows during escape sequence (backslash)
1232        processing, and also fixed erroneous offset values for syntax errors during
1233        backslash processing.
1234    
1235    17. Fixed another case of looking too far back in non-UTF-8 mode (cf 12 above)
1236        for patterns like [\PPP\x8a]{1,}\x80 with the subject "A\x80".
1237    
1238    18. An unterminated class in a pattern like (?1)\c[ with a "forward reference"
1239        caused an overrun.
1240    
1241    19. A pattern like (?:[\PPa*]*){8,} which had an "extended class" (one with
1242        something other than just ASCII characters) inside a group that had an
1243        unlimited repeat caused a loop at compile time (while checking to see
1244        whether the group could match an empty string).
1245    
1246    20. Debugging a pattern containing \p or \P could cause a crash. For example,
1247        [\P{Any}] did so. (Error in the code for printing property names.)
1248    
1249    21. An orphan \E inside a character class could cause a crash.
1250    
1251    22. A repeated capturing bracket such as (A)? could cause a wild memory
1252        reference during compilation.
1253    
1254    23. There are several functions in pcre_compile() that scan along a compiled
1255        expression for various reasons (e.g. to see if it's fixed length for look
1256        behind). There were bugs in these functions when a repeated \p or \P was
1257        present in the pattern. These operators have additional parameters compared
1258        with \d, etc, and these were not being taken into account when moving along
1259        the compiled data. Specifically:
1260    
1261        (a) A item such as \p{Yi}{3} in a lookbehind was not treated as fixed
1262            length.
1263    
1264        (b) An item such as \pL+ within a repeated group could cause crashes or
1265            loops.
1266    
1267        (c) A pattern such as \p{Yi}+(\P{Yi}+)(?1) could give an incorrect
1268            "reference to non-existent subpattern" error.
1269    
1270        (d) A pattern like (\P{Yi}{2}\277)? could loop at compile time.
1271    
1272    24. A repeated \S or \W in UTF-8 mode could give wrong answers when multibyte
1273        characters were involved (for example /\S{2}/8g with "A\x{a3}BC").
1274    
1275    25. Using pcregrep in multiline, inverted mode (-Mv) caused it to loop.
1276    
1277    26. Patterns such as [\P{Yi}A] which include \p or \P and just one other
1278        character were causing crashes (broken optimization).
1279    
1280    27. Patterns such as (\P{Yi}*\277)* (group with possible zero repeat containing
1281        \p or \P) caused a compile-time loop.
1282    
1283    28. More problems have arisen in unanchored patterns when CRLF is a valid line
1284        break. For example, the unstudied pattern [\r\n]A does not match the string
1285        "\r\nA" because change 7.0/46 below moves the current point on by two
1286        characters after failing to match at the start. However, the pattern \nA
1287        *does* match, because it doesn't start till \n, and if [\r\n]A is studied,
1288        the same is true. There doesn't seem any very clean way out of this, but
1289        what I have chosen to do makes the common cases work: PCRE now takes note
1290        of whether there can be an explicit match for \r or \n anywhere in the
1291        pattern, and if so, 7.0/46 no longer applies. As part of this change,
1292        there's a new PCRE_INFO_HASCRORLF option for finding out whether a compiled
1293        pattern has explicit CR or LF references.
1294    
1295    29. Added (*CR) etc for changing newline setting at start of pattern.
1296    
1297    
1298    Version 7.2 19-Jun-07
1299    ---------------------
1300    
1301     1. If the fr_FR locale cannot be found for test 3, try the "french" locale,
1302        which is apparently normally available under Windows.
1303    
1304     2. Re-jig the pcregrep tests with different newline settings in an attempt
1305        to make them independent of the local environment's newline setting.
1306    
1307     3. Add code to configure.ac to remove -g from the CFLAGS default settings.
1308    
1309     4. Some of the "internals" tests were previously cut out when the link size
1310        was not 2, because the output contained actual offsets. The recent new
1311        "Z" feature of pcretest means that these can be cut out, making the tests
1312        usable with all link sizes.
1313    
1314     5. Implemented Stan Switzer's goto replacement for longjmp() when not using
1315        stack recursion. This gives a massive performance boost under BSD, but just
1316        a small improvement under Linux. However, it saves one field in the frame
1317        in all cases.
1318    
1319     6. Added more features from the forthcoming Perl 5.10:
1320    
1321        (a) (?-n) (where n is a string of digits) is a relative subroutine or
1322            recursion call. It refers to the nth most recently opened parentheses.
1323    
1324        (b) (?+n) is also a relative subroutine call; it refers to the nth next
1325            to be opened parentheses.
1326    
1327        (c) Conditions that refer to capturing parentheses can be specified
1328            relatively, for example, (?(-2)... or (?(+3)...
1329    
1330        (d) \K resets the start of the current match so that everything before
1331            is not part of it.
1332    
1333        (e) \k{name} is synonymous with \k<name> and \k'name' (.NET compatible).
1334    
1335        (f) \g{name} is another synonym - part of Perl 5.10's unification of
1336            reference syntax.
1337    
1338        (g) (?| introduces a group in which the numbering of parentheses in each
1339            alternative starts with the same number.
1340    
1341        (h) \h, \H, \v, and \V match horizontal and vertical whitespace.
1342    
1343     7. Added two new calls to pcre_fullinfo(): PCRE_INFO_OKPARTIAL and
1344        PCRE_INFO_JCHANGED.
1345    
1346     8. A pattern such as  (.*(.)?)*  caused pcre_exec() to fail by either not
1347        terminating or by crashing. Diagnosed by Viktor Griph; it was in the code
1348        for detecting groups that can match an empty string.
1349    
1350     9. A pattern with a very large number of alternatives (more than several
1351        hundred) was running out of internal workspace during the pre-compile
1352        phase, where pcre_compile() figures out how much memory will be needed. A
1353        bit of new cunning has reduced the workspace needed for groups with
1354        alternatives. The 1000-alternative test pattern now uses 12 bytes of
1355        workspace instead of running out of the 4096 that are available.
1356    
1357    10. Inserted some missing (unsigned int) casts to get rid of compiler warnings.
1358    
1359    11. Applied patch from Google to remove an optimization that didn't quite work.
1360        The report of the bug said:
1361    
1362          pcrecpp::RE("a*").FullMatch("aaa") matches, while
1363          pcrecpp::RE("a*?").FullMatch("aaa") does not, and
1364          pcrecpp::RE("a*?\\z").FullMatch("aaa") does again.
1365    
1366    12. If \p or \P was used in non-UTF-8 mode on a character greater than 127
1367        it matched the wrong number of bytes.
1368    
1369    
1370    Version 7.1 24-Apr-07
1371    ---------------------
1372    
1373     1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
1374        that is more "standard", making use of automake and other Autotools. There
1375        is some re-arrangement of the files and adjustment of comments consequent
1376        on this.
1377    
1378     2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
1379        for recursive directory scanning broke on some systems because the files
1380        are not scanned in any specific order and on different systems the order
1381        was different. A call to "sort" has been inserted into RunGrepTest for the
1382        approprate test as a short-term fix. In the longer term there may be an
1383        alternative.
1384    
1385     3. I had an email from Eric Raymond about problems translating some of PCRE's
1386        man pages to HTML (despite the fact that I distribute HTML pages, some
1387        people do their own conversions for various reasons). The problems
1388        concerned the use of low-level troff macros .br and .in. I have therefore
1389        removed all such uses from the man pages (some were redundant, some could
1390        be replaced by .nf/.fi pairs). The 132html script that I use to generate
1391        HTML has been updated to handle .nf/.fi and to complain if it encounters
1392        .br or .in.
1393    
1394     4. Updated comments in configure.ac that get placed in config.h.in and also
1395        arranged for config.h to be included in the distribution, with the name
1396        config.h.generic, for the benefit of those who have to compile without
1397        Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
1398    
1399     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
1400        Weber: (1) pcre_internal.h was missing some function renames; (2) updated
1401        makevp.bat for the current PCRE, using the additional files
1402        makevp_c.txt, makevp_l.txt, and pcregexp.pas.
1403    
1404     6. A Windows user reported a minor discrepancy with test 2, which turned out
1405        to be caused by a trailing space on an input line that had got lost in his
1406        copy. The trailing space was an accident, so I've just removed it.
1407    
1408     7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
1409        that is needed.
1410    
1411     8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
1412        as "const" (a) because they are and (b) because it helps the PHP
1413        maintainers who have recently made a script to detect big data structures
1414        in the php code that should be moved to the .rodata section. I remembered
1415        to update Builducptable as well, so it won't revert if ucptable.h is ever
1416        re-created.
1417    
1418     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
1419        pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
1420        order to be able to cut out the UTF-8 tables in the latter when UTF-8
1421        support is not required. This saves 1.5-2K of code, which is important in
1422        some applications.
1423    
1424        Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
1425        so as not to refer to the tables, even though these functions will never be
1426        called when UTF-8 support is disabled. Otherwise there are problems with a
1427        shared library.
1428    
1429    10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
1430    
1431        (a) It was defining its arguments as char * instead of void *.
1432    
1433        (b) It was assuming that all moves were upwards in memory; this was true
1434            a long time ago when I wrote it, but is no longer the case.
1435    
1436        The emulated memove() is provided for those environments that have neither
1437        memmove() nor bcopy(). I didn't think anyone used it these days, but that
1438        is clearly not the case, as these two bugs were recently reported.
1439    
1440    11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
1441        and Detrail to create the HTML documentation, the .txt form of the man
1442        pages, and it removes trailing spaces from listed files. It also creates
1443        pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
1444        case, it wraps all the #defines with #ifndefs. This script should be run
1445        before "make dist".
1446    
1447    12. Fixed two fairly obscure bugs concerned with quantified caseless matching
1448        with Unicode property support.
1449    
1450        (a) For a maximizing quantifier, if the two different cases of the
1451            character were of different lengths in their UTF-8 codings (there are
1452            some cases like this - I found 11), and the matching function had to
1453            back up over a mixture of the two cases, it incorrectly assumed they
1454            were both the same length.
1455    
1456        (b) When PCRE was configured to use the heap rather than the stack for
1457            recursion during matching, it was not correctly preserving the data for
1458            the other case of a UTF-8 character when checking ahead for a match
1459            while processing a minimizing repeat. If the check also involved
1460            matching a wide character, but failed, corruption could cause an
1461            erroneous result when trying to check for a repeat of the original
1462            character.
1463    
1464    13. Some tidying changes to the testing mechanism:
1465    
1466        (a) The RunTest script now detects the internal link size and whether there
1467            is UTF-8 and UCP support by running ./pcretest -C instead of relying on
1468            values substituted by "configure". (The RunGrepTest script already did
1469            this for UTF-8.) The configure.ac script no longer substitutes the
1470            relevant variables.
1471    
1472        (b) The debugging options /B and /D in pcretest show the compiled bytecode
1473            with length and offset values. This means that the output is different
1474            for different internal link sizes. Test 2 is skipped for link sizes
1475            other than 2 because of this, bypassing the problem. Unfortunately,
1476            there was also a test in test 3 (the locale tests) that used /B and
1477            failed for link sizes other than 2. Rather than cut the whole test out,
1478            I have added a new /Z option to pcretest that replaces the length and
1479            offset values with spaces. This is now used to make test 3 independent
1480            of link size. (Test 2 will be tidied up later.)
1481    
1482    14. If erroroffset was passed as NULL to pcre_compile, it provoked a
1483        segmentation fault instead of returning the appropriate error message.
1484    
1485    15. In multiline mode when the newline sequence was set to "any", the pattern
1486        ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
1487        This doesn't seem right; it now treats the CRLF combination as the line
1488        ending, and so does not match in that case. It's only a pattern such as ^$
1489        that would hit this one: something like ^ABC$ would have failed after \r
1490        and then tried again after \r\n.
1491    
1492    16. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
1493        in an attempt to make files that differ only in their line terminators
1494        compare equal. This works on Linux.
1495    
1496    17. Under certain error circumstances pcregrep might try to free random memory
1497        as it exited. This is now fixed, thanks to valgrind.
1498    
1499    19. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
1500        "abc\r\n\r\n", it found an unwanted second match after the second \r. This
1501        was because its rules for how to advance for /g after matching an empty
1502        string at the end of a line did not allow for this case. They now check for
1503        it specially.
1504    
1505    20. pcretest is supposed to handle patterns and data of any length, by
1506        extending its buffers when necessary. It was getting this wrong when the
1507        buffer for a data line had to be extended.
1508    
1509    21. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or
1510        CRLF as a newline sequence.
1511    
1512    22. Code for handling Unicode properties in pcre_dfa_exec() wasn't being cut
1513        out by #ifdef SUPPORT_UCP. This did no harm, as it could never be used, but
1514        I have nevertheless tidied it up.
1515    
1516    23. Added some casts to kill warnings from HP-UX ia64 compiler.
1517    
1518    24. Added a man page for pcre-config.
1519    
1520    
1521    Version 7.0 19-Dec-06
1522    ---------------------
1523    
1524     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
1525        moving to gcc 4.1.1.
1526    
1527     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
1528        sys/time.h, which is documented as needed for this function. It doesn't
1529        seem to matter on Linux, but it showed up on some releases of OS X.
1530    
1531     3. It seems that there are systems where bytes whose values are greater than
1532        127 match isprint() in the "C" locale. The "C" locale should be the
1533        default when a C program starts up. In most systems, only ASCII printing
1534        characters match isprint(). This difference caused the output from pcretest
1535        to vary, making some of the tests fail. I have changed pcretest so that:
1536    
1537        (a) When it is outputting text in the compiled version of a pattern, bytes
1538            other than 32-126 are always shown as hex escapes.
1539    
1540        (b) When it is outputting text that is a matched part of a subject string,
1541            it does the same, unless a different locale has been set for the match
1542            (using the /L modifier). In this case, it uses isprint() to decide.
1543    
1544     4. Fixed a major bug that caused incorrect computation of the amount of memory
1545        required for a compiled pattern when options that changed within the
1546        pattern affected the logic of the preliminary scan that determines the
1547        length. The relevant options are -x, and -i in UTF-8 mode. The result was
1548        that the computed length was too small. The symptoms of this bug were
1549        either the PCRE error "internal error: code overflow" from pcre_compile(),
1550        or a glibc crash with a message such as "pcretest: free(): invalid next
1551        size (fast)". Examples of patterns that provoked this bug (shown in
1552        pcretest format) are:
1553    
1554          /(?-x: )/x
1555          /(?x)(?-x: \s*#\s*)/
1556          /((?i)[\x{c0}])/8
1557          /(?i:[\x{c0}])/8
1558    
1559        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
1560        is now done differently.
1561    
1562     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
1563        wrapper classes; (b) implement a new function in the C++ scanner that is
1564        more efficient than the old way of doing things because it avoids levels of
1565        recursion in the regex matching; (c) add a paragraph to the documentation
1566        for the FullMatch() function.
1567    
1568     6. The escape sequence \n was being treated as whatever was defined as
1569        "newline". Not only was this contrary to the documentation, which states
1570        that \n is character 10 (hex 0A), but it also went horribly wrong when
1571        "newline" was defined as CRLF. This has been fixed.
1572    
1573     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
1574        was being set to -1 for the "end of line" case (supposedly a value that no
1575        character can have). Though this value is never used (the check for end of
1576        line is "zero bytes in current character"), it caused compiler complaints.
1577        I've changed it to 0xffffffff.
1578    
1579     8. In pcre_version.c, the version string was being built by a sequence of
1580        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
1581        string (as it is for production releases) called a macro with an empty
1582        argument. The C standard says the result of this is undefined. The gcc
1583        compiler treats it as an empty string (which was what was wanted) but it is
1584        reported that Visual C gives an error. The source has been hacked around to
1585        avoid this problem.
1586    
1587     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
1588        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
1589        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
1590        of them did).
1591    
1592    10. Originally, pcretest opened its input and output without "b"; then I was
1593        told that "b" was needed in some environments, so it was added for release
1594        5.0 to both the input and output. (It makes no difference on Unix-like
1595        systems.) Later I was told that it is wrong for the input on Windows. I've
1596        now abstracted the modes into two macros, to make it easier to fiddle with
1597        them, and removed "b" from the input mode under Windows.
1598    
1599    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
1600    
1601    12. Added -help and --help to pcretest as an official way of being reminded
1602        of the options.
1603    
1604    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
1605        and pcrecpp.cc because they annoy compilers at high warning levels.
1606    
1607    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
1608    
1609    15. Fixed an occurrence of == in configure.ac that should have been = (shell
1610        scripts are not C programs :-) and which was not noticed because it works
1611        on Linux.
1612    
1613    16. pcretest is supposed to handle any length of pattern and data line (as one
1614        line or as a continued sequence of lines) by extending its input buffer if
1615        necessary. This feature was broken for very long pattern lines, leading to
1616        a string of junk being passed to pcre_compile() if the pattern was longer
1617        than about 50K.
1618    
1619    17. I have done a major re-factoring of the way pcre_compile() computes the
1620        amount of memory needed for a compiled pattern. Previously, there was code
1621        that made a preliminary scan of the pattern in order to do this. That was
1622        OK when PCRE was new, but as the facilities have expanded, it has become
1623        harder and harder to keep it in step with the real compile phase, and there
1624        have been a number of bugs (see for example, 4 above). I have now found a
1625        cunning way of running the real compile function in a "fake" mode that
1626        enables it to compute how much memory it would need, while actually only
1627        ever using a few hundred bytes of working memory and without too many
1628        tests of the mode. This should make future maintenance and development
1629        easier. A side effect of this work is that the limit of 200 on the nesting
1630        depth of parentheses has been removed (though this was never a serious
1631        limitation, I suspect). However, there is a downside: pcre_compile() now
1632        runs more slowly than before (30% or more, depending on the pattern). I
1633        hope this isn't a big issue. There is no effect on runtime performance.
1634    
1635    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
1636        newline (only possible for the last line of a file) and it was a
1637        pattern that set a locale (followed by /Lsomething), pcretest crashed.
1638    
1639    19. Added additional timing features to pcretest. (1) The -tm option now times
1640        matching only, not compiling. (2) Both -t and -tm can be followed, as a
1641        separate command line item, by a number that specifies the number of
1642        repeats to use when timing. The default is 50000; this gives better
1643        precision, but takes uncomfortably long for very large patterns.
1644    
1645    20. Extended pcre_study() to be more clever in cases where a branch of a
1646        subpattern has no definite first character. For example, (a*|b*)[cd] would
1647        previously give no result from pcre_study(). Now it recognizes that the
1648        first character must be a, b, c, or d.
1649    
1650    21. There was an incorrect error "recursive call could loop indefinitely" if
1651        a subpattern (or the entire pattern) that was being tested for matching an
1652        empty string contained only one non-empty item after a nested subpattern.
1653        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
1654        incorrectly, because the \d was being skipped in the check.
1655    
1656    22. The pcretest program now has a new pattern option /B and a command line
1657        option -b, which is equivalent to adding /B to every pattern. This causes
1658        it to show the compiled bytecode, without the additional information that
1659        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
1660        is the same as /B/I).
1661    
1662    23. A new optimization is now able automatically to treat some sequences such
1663        as a*b as a*+b. More specifically, if something simple (such as a character
1664        or a simple class like \d) has an unlimited quantifier, and is followed by
1665        something that cannot possibly match the quantified thing, the quantifier
1666        is automatically "possessified".
1667    
1668    24. A recursive reference to a subpattern whose number was greater than 39
1669        went wrong under certain circumstances in UTF-8 mode. This bug could also
1670        have affected the operation of pcre_study().
1671    
1672    25. Realized that a little bit of performance could be had by replacing
1673        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
1674    
1675    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
1676    
1677    27. Possessive quantifiers such as a++ were previously implemented by turning
1678        them into atomic groups such as ($>a+). Now they have their own opcodes,
1679        which improves performance. This includes the automatically created ones
1680        from 23 above.
1681    
1682    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
1683        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
1684        the first matched character to be a colon. This applied both to named and
1685        numbered groups.
1686    
1687    29. The ucpinternal.h header file was missing its idempotency #ifdef.
1688    
1689    30. I was sent a "project" file called libpcre.a.dev which I understand makes
1690        building PCRE on Windows easier, so I have included it in the distribution.
1691    
1692    31. There is now a check in pcretest against a ridiculously large number being
1693        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
1694        loop, the loop is abandoned.
1695    
1696    32. Forward references to subpatterns in conditions such as (?(2)...) where
1697        subpattern 2 is defined later cause pcre_compile() to search forwards in
1698        the pattern for the relevant set of parentheses. This search went wrong
1699        when there were unescaped parentheses in a character class, parentheses
1700        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
1701    
1702    33. "Subroutine" calls and backreferences were previously restricted to
1703        referencing subpatterns earlier in the regex. This restriction has now
1704        been removed.
1705    
1706    34. Added a number of extra features that are going to be in Perl 5.10. On the
1707        whole, these are just syntactic alternatives for features that PCRE had
1708        previously implemented using the Python syntax or my own invention. The
1709        other formats are all retained for compatibility.
1710    
1711        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
1712            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
1713            also .NET compatible.
1714    
1715        (b) A recursion or subroutine call to a named group can now be defined as
1716            (?&name) as well as (?P>name).
1717    
1718        (c) A backreference to a named group can now be defined as \k<name> or
1719            \k'name' as well as (?P=name). The new forms, as well as being in Perl
1720            5.10, are also .NET compatible.
1721    
1722        (d) A conditional reference to a named group can now use the syntax
1723            (?(<name>) or (?('name') as well as (?(name).
1724    
1725        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
1726            groups (named and numbered) that are never evaluated inline, but can be
1727            called as "subroutines" from elsewhere. In effect, the DEFINE condition
1728            is always false. There may be only one alternative in such a group.
1729    
1730        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
1731            as the simple (?(R). The condition is true only if the most recent
1732            recursion is that of the given number or name. It does not search out
1733            through the entire recursion stack.
1734    
1735        (g) The escape \gN or \g{N} has been added, where N is a positive or
1736            negative number, specifying an absolute or relative reference.
1737    
1738    35. Tidied to get rid of some further signed/unsigned compiler warnings and
1739        some "unreachable code" warnings.
1740    
1741    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
1742        things, this adds five new scripts.
1743    
1744    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
1745        There were also incompatibilities regarding the handling of \Q..\E inside
1746        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
1747        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
1748    
1749    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
1750        matches an empty string, and forcibly breaks the loop. There were bugs in
1751        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
1752        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
1753        separate and independent bugs (that affected different cases) have been
1754        fixed.
1755    
1756    39. Refactored the code to abolish the use of different opcodes for small
1757        capturing bracket numbers. This is a tidy that I avoided doing when I
1758        removed the limit on the number of capturing brackets for 3.5 back in 2001.
1759        The new approach is not only tidier, it makes it possible to reduce the
1760        memory needed to fix the previous bug (38).
1761    
1762    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
1763        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
1764        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
1765        mode.
1766    
1767    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
1768        report.
1769    
1770    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
1771        copy construction and assignment in the C++ wrapper.
1772    
1773    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
1774        couple of bugs that could have given wrong results in the "--newline=crlf"
1775        case.
1776    
1777    44. Added a number of casts and did some reorganization of signed/unsigned int
1778        variables following suggestions from Dair Grant. Also renamed the variable
1779        "this" as "item" because it is a C++ keyword.
1780    
1781    45. Arranged for dftables to add
1782    
1783          #include "pcre_internal.h"
1784    
1785        to pcre_chartables.c because without it, gcc 4.x may remove the array
1786        definition from the final binary if PCRE is built into a static library and
1787        dead code stripping is activated.
1788    
1789    46. For an unanchored pattern, if a match attempt fails at the start of a
1790        newline sequence, and the newline setting is CRLF or ANY, and the next two
1791        characters are CRLF, advance by two characters instead of one.
1792    
1793    
1794    Version 6.7 04-Jul-06
1795    ---------------------
1796    
1797     1. In order to handle tests when input lines are enormously long, pcretest has
1798        been re-factored so that it automatically extends its buffers when
1799        necessary. The code is crude, but this _is_ just a test program. The
1800        default size has been increased from 32K to 50K.
1801    
1802     2. The code in pcre_study() was using the value of the re argument before
1803        testing it for NULL. (Of course, in any sensible call of the function, it
1804        won't be NULL.)
1805    
1806     3. The memmove() emulation function in pcre_internal.h, which is used on
1807        systems that lack both memmove() and bcopy() - that is, hardly ever -
1808        was missing a "static" storage class specifier.
1809    
1810     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
1811        containing an extended class (one that cannot be represented by a bitmap
1812        because it contains high-valued characters or Unicode property items, e.g.
1813        [\pZ]). Almost always one would set UTF-8 mode when processing such a
1814        pattern, but PCRE should not loop if you do not (it no longer does).
1815        [Detail: two cases were found: (a) a repeated subpattern containing an
1816        extended class; (b) a recursive reference to a subpattern that followed a
1817        previous extended class. It wasn't skipping over the extended class
1818        correctly when UTF-8 mode was not set.]
1819    
1820     5. A negated single-character class was not being recognized as fixed-length
1821        in lookbehind assertions such as (?<=[^f]), leading to an incorrect
1822        compile error "lookbehind assertion is not fixed length".
1823    
1824     6. The RunPerlTest auxiliary script was showing an unexpected difference
1825        between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
1826        write a Perl script that can interpret lines of an input file either as
1827        byte characters or as UTF-8, which is what "perltest" was being required to
1828        do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
1829        can't do is switch easily at run time between having the "use utf8;" pragma
1830        or not. In the end, I fudged it by using the RunPerlTest script to insert
1831        "use utf8;" explicitly for the UTF-8 tests.
1832    
1833     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
1834        the end of the subject string, contrary to the documentation and to what
1835        Perl does. This was true of both matching functions. Now it matches only at
1836        the start of the subject and immediately after *internal* newlines.
1837    
1838     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
1839        a pointer to an int instead of a pointer to an unsigned long int. This
1840        caused problems on 64-bit systems.
1841    
1842     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
1843        instance of the 'standard' template library not being so standard".
1844    
1845    10. There was no check on the number of named subpatterns nor the maximum
1846        length of a subpattern name. The product of these values is used to compute
1847        the size of the memory block for a compiled pattern. By supplying a very
1848        long subpattern name and a large number of named subpatterns, the size
1849        computation could be caused to overflow. This is now prevented by limiting
1850        the length of names to 32 characters, and the number of named subpatterns
1851        to 10,000.
1852    
1853    11. Subpatterns that are repeated with specific counts have to be replicated in
1854        the compiled pattern. The size of memory for this was computed from the
1855        length of the subpattern and the repeat count. The latter is limited to
1856        65535, but there was no limit on the former, meaning that integer overflow
1857        could in principle occur. The compiled length of a repeated subpattern is
1858        now limited to 30,000 bytes in order to prevent this.
1859    
1860    12. Added the optional facility to have named substrings with the same name.
1861    
1862    13. Added the ability to use a named substring as a condition, using the
1863        Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
1864        are numbers (not recommended). Forward references are permitted.
1865    
1866    14. Added forward references in named backreferences (if you see what I mean).
1867    
1868    15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
1869        pattern could run off the end of the subject. For example, the pattern
1870        "(?s)(.{1,5})"8 did this with the subject "ab".
1871    
1872    16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
1873        PCRE_CASELESS was set when matching characters that were quantified with ?
1874        or *.
1875    
1876    17. A character class other than a single negated character that had a minimum
1877        but no maximum quantifier - for example [ab]{6,} - was not handled
1878        correctly by pce_dfa_exec(). It would match only one character.
1879    
1880    18. A valid (though odd) pattern that looked like a POSIX character
1881        class but used an invalid character after [ (for example [[,abc,]]) caused
1882        pcre_compile() to give the error "Failed: internal error: code overflow" or
1883        in some cases to crash with a glibc free() error. This could even happen if
1884        the pattern terminated after [[ but there just happened to be a sequence of
1885        letters, a binary zero, and a closing ] in the memory that followed.
1886    
1887    19. Perl's treatment of octal escapes in the range \400 to \777 has changed
1888        over the years. Originally (before any Unicode support), just the bottom 8
1889        bits were taken. Thus, for example, \500 really meant \100. Nowadays the
1890        output from "man perlunicode" includes this:
1891    
1892          The regular expression compiler produces polymorphic opcodes.  That
1893          is, the pattern adapts to the data and automatically switches to
1894          the Unicode character scheme when presented with Unicode data--or
1895          instead uses a traditional byte scheme when presented with byte
1896          data.
1897    
1898        Sadly, a wide octal escape does not cause a switch, and in a string with
1899        no other multibyte characters, these octal escapes are treated as before.
1900        Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
1901        /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
1902        Unicode string.
1903    
1904        I have not perpetrated such confusion in PCRE. Up till now, it took just
1905        the bottom 8 bits, as in old Perl. I have now made octal escapes with
1906        values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
1907        translate to the appropriate multibyte character.
1908    
1909    29. Applied some refactoring to reduce the number of warnings from Microsoft
1910        and Borland compilers. This has included removing the fudge introduced
1911        seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
1912        a warning about an unused variable.
1913    
1914    21. PCRE has not included VT (character 0x0b) in the set of whitespace
1915        characters since release 4.0, because Perl (from release 5.004) does not.
1916        [Or at least, is documented not to: some releases seem to be in conflict
1917        with the documentation.] However, when a pattern was studied with
1918        pcre_study() and all its branches started with \s, PCRE still included VT
1919        as a possible starting character. Of course, this did no harm; it just
1920        caused an unnecessary match attempt.
1921    
1922    22. Removed a now-redundant internal flag bit that recorded the fact that case
1923        dependency changed within the pattern. This was once needed for "required
1924        byte" processing, but is no longer used. This recovers a now-scarce options
1925        bit. Also moved the least significant internal flag bit to the most-
1926        significant bit of the word, which was not previously used (hangover from
1927        the days when it was an int rather than a uint) to free up another bit for
1928        the future.
1929    
1930    23. Added support for CRLF line endings as well as CR and LF. As well as the
1931        default being selectable at build time, it can now be changed at runtime
1932        via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
1933        specify that it is scanning data with non-default line endings.
1934    
1935    24. Changed the definition of CXXLINK to make it agree with the definition of
1936        LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
1937    
1938    25. Applied Ian Taylor's patches to avoid using another stack frame for tail
1939        recursions. This makes a big different to stack usage for some patterns.
1940    
1941    26. If a subpattern containing a named recursion or subroutine reference such
1942        as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
1943        the space required for the compiled pattern went wrong and gave too small a
1944        value. Depending on the environment, this could lead to "Failed: internal
1945        error: code overflow at offset 49" or "glibc detected double free or
1946        corruption" errors.
1947    
1948    27. Applied patches from Google (a) to support the new newline modes and (b) to
1949        advance over multibyte UTF-8 characters in GlobalReplace.
1950    
1951    28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
1952        difference for some implementation of PCRE in some Windows version.
1953    
1954    29. Added some extra testing facilities to pcretest:
1955    
1956        \q<number>   in a data line sets the "match limit" value
1957        \Q<number>   in a data line sets the "match recursion limt" value
1958        -S <number>  sets the stack size, where <number> is in megabytes
1959    
1960        The -S option isn't available for Windows.
1961    
1962    
1963    Version 6.6 06-Feb-06
1964    ---------------------
1965    
1966     1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
1967        in pcreposix.h. I have copied the definition from pcre.h.
1968    
1969     2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
1970        because pcre.h is no longer a built file.
1971    
1972     3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
1973        not normally included in the compiled code.
1974    
1975    
1976    Version 6.5 01-Feb-06
1977    ---------------------
1978    
1979     1. When using the partial match feature with pcre_dfa_exec(), it was not
1980        anchoring the second and subsequent partial matches at the new starting
1981        point. This could lead to incorrect results. For example, with the pattern
1982        /1234/, partially matching against "123" and then "a4" gave a match.
1983    
1984     2. Changes to pcregrep:
1985    
1986        (a) All non-match returns from pcre_exec() were being treated as failures
1987            to match the line. Now, unless the error is PCRE_ERROR_NOMATCH, an
1988            error message is output. Some extra information is given for the
1989            PCRE_ERROR_MATCHLIMIT and PCRE_ERROR_RECURSIONLIMIT errors, which are
1990            probably the only errors that are likely to be caused by users (by
1991            specifying a regex that has nested indefinite repeats, for instance).
1992            If there are more than 20 of these errors, pcregrep is abandoned.
1993    
1994        (b) A binary zero was treated as data while matching, but terminated the
1995            output line if it was written out. This has been fixed: binary zeroes
1996            are now no different to any other data bytes.
1997    
1998        (c) Whichever of the LC_ALL or LC_CTYPE environment variables is set is
1999            used to set a locale for matching. The --locale=xxxx long option has
2000            been added (no short equivalent) to specify a locale explicitly on the
2001            pcregrep command, overriding the environment variables.
2002    
2003        (d) When -B was used with -n, some line numbers in the output were one less
2004            than they should have been.
2005    
2006        (e) Added the -o (--only-matching) option.
2007    
2008        (f) If -A or -C was used with -c (count only), some lines of context were
2009            accidentally printed for the final match.
2010    
2011        (g) Added the -H (--with-filename) option.
2012    
2013        (h) The combination of options -rh failed to suppress file names for files
2014            that were found from directory arguments.
2015    
2016        (i) Added the -D (--devices) and -d (--directories) options.
2017    
2018        (j) Added the -F (--fixed-strings) option.
2019    
2020        (k) Allow "-" to be used as a file name for -f as well as for a data file.
2021    
2022        (l) Added the --colo(u)r option.
2023    
2024        (m) Added Jeffrey Friedl's -S testing option, but within #ifdefs so that it
2025            is not present by default.
2026    
2027     3. A nasty bug was discovered in the handling of recursive patterns, that is,
2028        items such as (?R) or (?1), when the recursion could match a number of
2029        alternatives. If it matched one of the alternatives, but subsequently,
2030        outside the recursion, there was a failure, the code tried to back up into
2031        the recursion. However, because of the way PCRE is implemented, this is not
2032        possible, and the result was an incorrect result from the match.
2033    
2034        In order to prevent this happening, the specification of recursion has
2035        been changed so that all such subpatterns are automatically treated as
2036        atomic groups. Thus, for example, (?R) is treated as if it were (?>(?R)).
2037    
2038     4. I had overlooked the fact that, in some locales, there are characters for
2039        which isalpha() is true but neither isupper() nor islower() are true. In
2040        the fr_FR locale, for instance, the \xAA and \xBA characters (ordmasculine
2041        and ordfeminine) are like this. This affected the treatment of \w and \W
2042        when they appeared in character classes, but not when they appeared outside
2043        a character class. The bit map for "word" characters is now created
2044        separately from the results of isalnum() instead of just taking it from the
2045        upper, lower, and digit maps. (Plus the underscore character, of course.)
2046    
2047     5. The above bug also affected the handling of POSIX character classes such as
2048        [[:alpha:]] and [[:alnum:]]. These do not have their own bit maps in PCRE's
2049        permanent tables. Instead, the bit maps for such a class were previously
2050        created as the appropriate unions of the upper, lower, and digit bitmaps.
2051        Now they are created by subtraction from the [[:word:]] class, which has
2052        its own bitmap.
2053    
2054     6. The [[:blank:]] character class matches horizontal, but not vertical space.
2055        It is created by subtracting the vertical space characters (\x09, \x0a,
2056        \x0b, \x0c) from the [[:space:]] bitmap. Previously, however, the
2057        subtraction was done in the overall bitmap for a character class, meaning
2058        that a class such as [\x0c[:blank:]] was incorrect because \x0c would not
2059        be recognized. This bug has been fixed.
2060    
2061     7. Patches from the folks at Google:
2062    
2063          (a) pcrecpp.cc: "to handle a corner case that may or may not happen in
2064          real life, but is still worth protecting against".
2065    
2066          (b) pcrecpp.cc: "corrects a bug when negative radixes are used with
2067          regular expressions".
2068    
2069          (c) pcre_scanner.cc: avoid use of std::count() because not all systems
2070          have it.
2071    
2072          (d) Split off pcrecpparg.h from pcrecpp.h and had the former built by
2073          "configure" and the latter not, in order to fix a problem somebody had
2074          with compiling the Arg class on HP-UX.
2075    
2076          (e) Improve the error-handling of the C++ wrapper a little bit.
2077    
2078          (f) New tests for checking recursion limiting.
2079    
2080     8. The pcre_memmove() function, which is used only if the environment does not
2081        have a standard memmove() function (and is therefore rarely compiled),
2082        contained two bugs: (a) use of int instead of size_t, and (b) it was not
2083        returning a result (though PCRE never actually uses the result).
2084    
2085     9. In the POSIX regexec() interface, if nmatch is specified as a ridiculously
2086        large number - greater than INT_MAX/(3*sizeof(int)) - REG_ESPACE is
2087        returned instead of calling malloc() with an overflowing number that would
2088        most likely cause subsequent chaos.
2089    
2090    10. The debugging option of pcretest was not showing the NO_AUTO_CAPTURE flag.
2091    
2092    11. The POSIX flag REG_NOSUB is now supported. When a pattern that was compiled
2093        with this option is matched, the nmatch and pmatch options of regexec() are
2094        ignored.
2095    
2096    12. Added REG_UTF8 to the POSIX interface. This is not defined by POSIX, but is
2097        provided in case anyone wants to the the POSIX interface with UTF-8
2098        strings.
2099    
2100    13. Added CXXLDFLAGS to the Makefile parameters to provide settings only on the
2101        C++ linking (needed for some HP-UX environments).
2102    
2103    14. Avoid compiler warnings in get_ucpname() when compiled without UCP support
2104        (unused parameter) and in the pcre_printint() function (omitted "default"
2105        switch label when the default is to do nothing).
2106    
2107    15. Added some code to make it possible, when PCRE is compiled as a C++
2108        library, to replace subject pointers for pcre_exec() with a smart pointer
2109        class, thus making it possible to process discontinuous strings.
2110    
2111    16. The two macros PCRE_EXPORT and PCRE_DATA_SCOPE are confusing, and perform
2112        much the same function. They were added by different people who were trying
2113        to make PCRE easy to compile on non-Unix systems. It has been suggested
2114        that PCRE_EXPORT be abolished now that there is more automatic apparatus
2115        for compiling on Windows systems. I have therefore replaced it with
2116        PCRE_DATA_SCOPE. This is set automatically for Windows; if not set it
2117        defaults to "extern" for C or "extern C" for C++, which works fine on
2118        Unix-like systems. It is now possible to override the value of PCRE_DATA_
2119        SCOPE with something explicit in config.h. In addition:
2120    
2121        (a) pcreposix.h still had just "extern" instead of either of these macros;
2122            I have replaced it with PCRE_DATA_SCOPE.
2123    
2124        (b) Functions such as _pcre_xclass(), which are internal to the library,
2125            but external in the C sense, all had PCRE_EXPORT in their definitions.
2126            This is apparently wrong for the Windows case, so I have removed it.
2127            (It makes no difference on Unix-like systems.)
2128    
2129    17. Added a new limit, MATCH_LIMIT_RECURSION, which limits the depth of nesting
2130        of recursive calls to match(). This is different to MATCH_LIMIT because
2131        that limits the total number of calls to match(), not all of which increase
2132        the depth of recursion. Limiting the recursion depth limits the amount of
2133        stack (or heap if NO_RECURSE is set) that is used. The default can be set
2134        when PCRE is compiled, and changed at run time. A patch from Google adds
2135        this functionality to the C++ interface.
2136    
2137    18. Changes to the handling of Unicode character properties:
2138    
2139        (a) Updated the table to Unicode 4.1.0.
2140    
2141        (b) Recognize characters that are not in the table as "Cn" (undefined).
2142    
2143        (c) I revised the way the table is implemented to a much improved format
2144            which includes recognition of ranges. It now supports the ranges that
2145            are defined in UnicodeData.txt, and it also amalgamates other
2146            characters into ranges. This has reduced the number of entries in the
2147            table from around 16,000 to around 3,000, thus reducing its size
2148            considerably. I realized I did not need to use a tree structure after
2149            all - a binary chop search is just as efficient. Having reduced the
2150            number of entries, I extended their size from 6 bytes to 8 bytes to
2151            allow for more data.
2152    
2153        (d) Added support for Unicode script names via properties such as \p{Han}.
2154    
2155    19. In UTF-8 mode, a backslash followed by a non-Ascii character was not
2156        matching that character.
2157    
2158    20. When matching a repeated Unicode property with a minimum greater than zero,
2159        (for example \pL{2,}), PCRE could look past the end of the subject if it
2160        reached it while seeking the minimum number of characters. This could
2161        happen only if some of the characters were more than one byte long, because
2162        there is a check for at least the minimum number of bytes.
2163    
2164    21. Refactored the implementation of \p and \P so as to be more general, to
2165        allow for more different types of property in future. This has changed the
2166        compiled form incompatibly. Anybody with saved compiled patterns that use
2167        \p or \P will have to recompile them.
2168    
2169    22. Added "Any" and "L&" to the supported property types.
2170    
2171    23. Recognize \x{...} as a code point specifier, even when not in UTF-8 mode,
2172        but give a compile time error if the value is greater than 0xff.
2173    
2174    24. The man pages for pcrepartial, pcreprecompile, and pcre_compile2 were
2175        accidentally not being installed or uninstalled.
2176    
2177    25. The pcre.h file was built from pcre.h.in, but the only changes that were
2178        made were to insert the current release number. This seemed silly, because
2179        it made things harder for people building PCRE on systems that don't run
2180        "configure". I have turned pcre.h into a distributed file, no longer built
2181        by "configure", with the version identification directly included. There is
2182        no longer a pcre.h.in file.
2183    
2184        However, this change necessitated a change to the pcre-config script as
2185        well. It is built from pcre-config.in, and one of the substitutions was the
2186        release number. I have updated configure.ac so that ./configure now finds
2187        the release number by grepping pcre.h.
2188    
2189    26. Added the ability to run the tests under valgrind.
2190    
2191    
2192    Version 6.4 05-Sep-05
2193    ---------------------
2194    
2195     1. Change 6.0/10/(l) to pcregrep introduced a bug that caused separator lines
2196        "--" to be printed when multiple files were scanned, even when none of the
2197        -A, -B, or -C options were used. This is not compatible with Gnu grep, so I
2198        consider it to be a bug, and have restored the previous behaviour.
2199    
2200     2. A couple of code tidies to get rid of compiler warnings.
2201    
2202     3. The pcretest program used to cheat by referring to symbols in the library
2203        whose names begin with _pcre_. These are internal symbols that are not
2204        really supposed to be visible externally, and in some environments it is
2205        possible to suppress them. The cheating is now confined to including
2206        certain files from the library's source, which is a bit cleaner.
2207    
2208     4. Renamed pcre.in as pcre.h.in to go with pcrecpp.h.in; it also makes the
2209        file's purpose clearer.
2210    
2211     5. Reorganized pcre_ucp_findchar().
2212    
2213    
2214    Version 6.3 15-Aug-05
2215    ---------------------
2216    
2217     1. The file libpcre.pc.in did not have general read permission in the tarball.
2218    
2219     2. There were some problems when building without C++ support:
2220    
2221        (a) If C++ support was not built, "make install" and "make test" still
2222            tried to test it.
2223    
2224        (b) There were problems when the value of CXX was explicitly set. Some
2225            changes have been made to try to fix these, and ...
2226    
2227        (c) --disable-cpp can now be used to explicitly disable C++ support.
2228    
2229        (d) The use of @CPP_OBJ@ directly caused a blank line preceded by a
2230            backslash in a target when C++ was disabled. This confuses some
2231            versions of "make", apparently. Using an intermediate variable solves
2232            this. (Same for CPP_LOBJ.)
2233    
2234     3. $(LINK_FOR_BUILD) now includes $(CFLAGS_FOR_BUILD) and $(LINK)
2235        (non-Windows) now includes $(CFLAGS) because these flags are sometimes
2236        necessary on certain architectures.
2237    
2238     4. Added a setting of -export-symbols-regex to the link command to remove
2239        those symbols that are exported in the C sense, but actually are local
2240        within the library, and not documented. Their names all begin with
2241        "_pcre_". This is not a perfect job, because (a) we have to except some
2242        symbols that pcretest ("illegally") uses, and (b) the facility isn't always
2243        available (and never for static libraries). I have made a note to try to
2244        find a way round (a) in the future.
2245    
2246    
2247    Version 6.2 01-Aug-05
2248    ---------------------
2249    
2250     1. There was no test for integer overflow of quantifier values. A construction
2251        such as {1111111111111111} would give undefined results. What is worse, if
2252        a minimum quantifier for a parenthesized subpattern overflowed and became
2253        negative, the calculation of the memory size went wrong. This could have
2254        led to memory overwriting.
2255    
2256     2. Building PCRE using VPATH was broken. Hopefully it is now fixed.
2257    
2258     3. Added "b" to the 2nd argument of fopen() in dftables.c, for non-Unix-like
2259        operating environments where this matters.
2260    
2261     4. Applied Giuseppe Maxia's patch to add additional features for controlling
2262        PCRE options from within the C++ wrapper.
2263    
2264     5. Named capturing subpatterns were not being correctly counted when a pattern
2265        was compiled. This caused two problems: (a) If there were more than 100
2266        such subpatterns, the calculation of the memory needed for the whole
2267        compiled pattern went wrong, leading to an overflow error. (b) Numerical
2268        back references of the form \12, where the number was greater than 9, were
2269        not recognized as back references, even though there were sufficient
2270        previous subpatterns.
2271    
2272     6. Two minor patches to pcrecpp.cc in order to allow it to compile on older
2273        versions of gcc, e.g. 2.95.4.
2274    
2275    
2276    Version 6.1 21-Jun-05
2277    ---------------------
2278    
2279     1. There was one reference to the variable "posix" in pcretest.c that was not
2280        surrounded by "#if !defined NOPOSIX".
2281    
2282     2. Make it possible to compile pcretest without DFA support, UTF8 support, or
2283        the cross-check on the old pcre_info() function, for the benefit of the
2284        cut-down version of PCRE that is currently imported into Exim.
2285    
2286     3. A (silly) pattern starting with (?i)(?-i) caused an internal space
2287        allocation error. I've done the easy fix, which wastes 2 bytes for sensible
2288        patterns that start (?i) but I don't think that matters. The use of (?i) is
2289        just an example; this all applies to the other options as well.
2290    
2291     4. Since libtool seems to echo the compile commands it is issuing, the output
2292        from "make" can be reduced a bit by putting "@" in front of each libtool
2293        compile command.
2294    
2295     5. Patch from the folks at Google for configure.in to be a bit more thorough
2296        in checking for a suitable C++ installation before trying to compile the
2297        C++ stuff. This should fix a reported problem when a compiler was present,
2298        but no suitable headers.
2299    
2300     6. The man pages all had just "PCRE" as their title. I have changed them to
2301        be the relevant file name. I have also arranged that these names are
2302        retained in the file doc/pcre.txt, which is a concatenation in text format
2303        of all the man pages except the little individual ones for each function.
2304    
2305     7. The NON-UNIX-USE file had not been updated for the different set of source
2306        files that come with release 6. I also added a few comments about the C++
2307        wrapper.
2308    
2309    
2310    Version 6.0 07-Jun-05
2311    ---------------------
2312    
2313     1. Some minor internal re-organization to help with my DFA experiments.
2314    
2315     2. Some missing #ifdef SUPPORT_UCP conditionals in pcretest and printint that
2316        didn't matter for the library itself when fully configured, but did matter
2317        when compiling without UCP support, or within Exim, where the ucp files are
2318        not imported.
2319    
2320     3. Refactoring of the library code to split up the various functions into
2321        different source modules. The addition of the new DFA matching code (see
2322        below) to a single monolithic source would have made it really too
2323        unwieldy, quite apart from causing all the code to be include in a
2324        statically linked application, when only some functions are used. This is
2325        relevant even without the DFA addition now that patterns can be compiled in
2326        one application and matched in another.
2327    
2328        The downside of splitting up is that there have to be some external
2329        functions and data tables that are used internally in different modules of
2330        the library but which are not part of the API. These have all had their
2331        names changed to start with "_pcre_" so that they are unlikely to clash
2332        with other external names.
2333    
2334     4. Added an alternate matching function, pcre_dfa_exec(), which matches using
2335        a different (DFA) algorithm. Although it is slower than the original
2336        function, it does have some advantages for certain types of matching
2337        problem.
2338    
2339     5. Upgrades to pcretest in order to test the features of pcre_dfa_exec(),
2340        including restarting after a partial match.
2341    
2342     6. A patch for pcregrep that defines INVALID_FILE_ATTRIBUTES if it is not
2343        defined when compiling for Windows was sent to me. I have put it into the
2344        code, though I have no means of testing or verifying it.
2345    
2346     7. Added the pcre_refcount() auxiliary function.
2347    
2348     8. Added the PCRE_FIRSTLINE option. This constrains an unanchored pattern to
2349        match before or at the first newline in the subject string. In pcretest,
2350        the /f option on a pattern can be used to set this.
2351    
2352     9. A repeated \w when used in UTF-8 mode with characters greater than 256
2353        would behave wrongly. This has been present in PCRE since release 4.0.
2354    
2355    10. A number of changes to the pcregrep command:
2356    
2357        (a) Refactored how -x works; insert ^(...)$ instead of setting
2358            PCRE_ANCHORED and checking the length, in preparation for adding
2359            something similar for -w.
2360    
2361        (b) Added the -w (match as a word) option.
2362    
2363        (c) Refactored the way lines are read and buffered so as to have more
2364            than one at a time available.
2365    
2366        (d) Implemented a pcregrep test script.
2367    
2368        (e) Added the -M (multiline match) option. This allows patterns to match
2369            over several lines of the subject. The buffering ensures that at least
2370            8K, or the rest of the document (whichever is the shorter) is available
2371            for matching (and similarly the previous 8K for lookbehind assertions).
2372    
2373        (f) Changed the --help output so that it now says
2374    
2375              -w, --word-regex(p)
2376    
2377            instead of two lines, one with "regex" and the other with "regexp"
2378            because that confused at least one person since the short forms are the
2379            same. (This required a bit of code, as the output is generated
2380            automatically from a table. It wasn't just a text change.)
2381    
2382        (g) -- can be used to terminate pcregrep options if the next thing isn't an
2383            option but starts with a hyphen. Could be a pattern or a path name
2384            starting with a hyphen, for instance.
2385    
2386        (h) "-" can be given as a file name to represent stdin.
2387    
2388        (i) When file names are being printed, "(standard input)" is used for
2389            the standard input, for compatibility with GNU grep. Previously
2390            "<stdin>" was used.
2391    
2392        (j) The option --label=xxx can be used to supply a name to be used for
2393            stdin when file names are being printed. There is no short form.
2394    
2395        (k) Re-factored the options decoding logic because we are going to add
2396            two more options that take data. Such options can now be given in four
2397            different ways, e.g. "-fname", "-f name", "--file=name", "--file name".
2398    
2399        (l) Added the -A, -B, and -C options for requesting that lines of context
2400            around matches be printed.
2401    
2402        (m) Added the -L option to print the names of files that do not contain
2403            any matching lines, that is, the complement of -l.
2404    
2405        (n) The return code is 2 if any file cannot be opened, but pcregrep does
2406            continue to scan other files.
2407    
2408        (o) The -s option was incorrectly implemented. For compatibility with other
2409            greps, it now suppresses the error message for a non-existent or non-
2410            accessible file (but not the return code). There is a new option called
2411            -q that suppresses the output of matching lines, which was what -s was
2412            previously doing.
2413    
2414        (p) Added --include and --exclude options to specify files for inclusion
2415            and exclusion when recursing.
2416    
2417    11. The Makefile was not using the Autoconf-supported LDFLAGS macro properly.
2418        Hopefully, it now does.
2419    
2420    12. Missing cast in pcre_study().
2421    
2422    13. Added an "uninstall" target to the makefile.
2423    
2424    14. Replaced "extern" in the function prototypes in Makefile.in with
2425        "PCRE_DATA_SCOPE", which defaults to 'extern' or 'extern "C"' in the Unix
2426        world, but is set differently for Windows.
2427    
2428    15. Added a second compiling function called pcre_compile2(). The only
2429        difference is that it has an extra argument, which is a pointer to an
2430        integer error code. When there is a compile-time failure, this is set
2431        non-zero, in addition to the error test pointer being set to point to an
2432        error message. The new argument may be NULL if no error number is required
2433        (but then you may as well call pcre_compile(), which is now just a
2434        wrapper). This facility is provided because some applications need a
2435        numeric error indication, but it has also enabled me to tidy up the way
2436        compile-time errors are handled in the POSIX wrapper.
2437    
2438    16. Added VPATH=.libs to the makefile; this should help when building with one
2439        prefix path and installing with another. (Or so I'm told by someone who
2440        knows more about this stuff than I do.)
2441    
2442    17. Added a new option, REG_DOTALL, to the POSIX function regcomp(). This
2443        passes PCRE_DOTALL to the pcre_compile() function, making the "." character
2444        match everything, including newlines. This is not POSIX-compatible, but
2445        somebody wanted the feature. From pcretest it can be activated by using
2446        both the P and the s flags.
2447    
2448    18. AC_PROG_LIBTOOL appeared twice in Makefile.in. Removed one.
2449    
2450    19. libpcre.pc was being incorrectly installed as executable.
2451    
2452    20. A couple of places in pcretest check for end-of-line by looking for '\n';
2453        it now also looks for '\r' so that it will work unmodified on Windows.
2454    
2455    21. Added Google's contributed C++ wrapper to the distribution.
2456    
2457    22. Added some untidy missing memory free() calls in pcretest, to keep
2458        Electric Fence happy when testing.
2459    
2460    
2461    
2462    Version 5.0 13-Sep-04
2463    ---------------------
2464    
2465     1. Internal change: literal characters are no longer packed up into items
2466        containing multiple characters in a single byte-string. Each character
2467        is now matched using a separate opcode. However, there may be more than one
2468        byte in the character in UTF-8 mode.
2469    
2470     2. The pcre_callout_block structure has two new fields: pattern_position and
2471        next_item_length. These contain the offset in the pattern to the next match
2472        item, and its length, respectively.
2473    
2474     3. The PCRE_AUTO_CALLOUT option for pcre_compile() requests the automatic
2475        insertion of callouts before each pattern item. Added the /C option to
2476        pcretest to make use of this.
2477    
2478     4. On the advice of a Windows user, the lines
2479    
2480          #if defined(_WIN32) || defined(WIN32)
2481          _setmode( _fileno( stdout ), 0x8000 );
2482          #endif  /* defined(_WIN32) || defined(WIN32) */
2483    
2484        have been added to the source of pcretest. This apparently does useful
2485        magic in relation to line terminators.
2486    
2487     5. Changed "r" and "w" in the calls to fopen() in pcretest to "rb" and "wb"
2488        for the benefit of those environments where the "b" makes a difference.
2489    
2490     6. The icc compiler has the same options as gcc, but "configure" doesn't seem
2491        to know about it. I have put a hack into configure.in that adds in code
2492        to set GCC=yes if CC=icc. This seems to end up at a point in the
2493        generated configure script that is early enough to affect the setting of
2494        compiler options, which is what is needed, but I have no means of testing
2495        whether it really works. (The user who reported this had patched the
2496        generated configure script, which of course I cannot do.)
2497    
2498        LATER: After change 22 below (new libtool files), the configure script
2499        seems to know about icc (and also ecc). Therefore, I have commented out
2500        this hack in configure.in.
2501    
2502     7. Added support for pkg-config (2 patches were sent in).
2503    
2504     8. Negated POSIX character classes that used a combination of internal tables
2505        were completely broken. These were [[:^alpha:]], [[:^alnum:]], and
2506        [[:^ascii]]. Typically, they would match almost any characters. The other
2507        POSIX classes were not broken in this way.
2508    
2509     9. Matching the pattern "\b.*?" against "ab cd", starting at offset 1, failed
2510        to find the match, as PCRE was deluded into thinking that the match had to
2511        start at the start point or following a newline. The same bug applied to
2512        patterns with negative forward assertions or any backward assertions
2513        preceding ".*" at the start, unless the pattern required a fixed first
2514        character. This was a failing pattern: "(?!.bcd).*". The bug is now fixed.
2515    
2516    10. In UTF-8 mode, when moving forwards in the subject after a failed match
2517        starting at the last subject character, bytes beyond the end of the subject
2518        string were read.
2519    
2520    11. Renamed the variable "class" as "classbits" to make life easier for C++
2521        users. (Previously there was a macro definition, but it apparently wasn't
2522        enough.)
2523    
2524    12. Added the new field "tables" to the extra data so that tables can be passed
2525        in at exec time, or the internal tables can be re-selected. This allows
2526        a compiled regex to be saved and re-used at a later time by a different
2527        program that might have everything at different addresses.
2528    
2529    13. Modified the pcre-config script so that, when run on Solaris, it shows a
2530        -R library as well as a -L library.
2531    
2532    14. The debugging options of pcretest (-d on the command line or D on a
2533        pattern) showed incorrect output for anything following an extended class
2534        that contained multibyte characters and which was followed by a quantifier.
2535    
2536    15. Added optional support for general category Unicode character properties
2537        via the \p, \P, and \X escapes. Unicode property support implies UTF-8
2538        support. It adds about 90K to the size of the library. The meanings of the
2539        inbuilt class escapes such as \d and \s have NOT been changed.
2540    
2541    16. Updated pcredemo.c to include calls to free() to release the memory for the
2542        compiled pattern.
2543    
2544    17. The generated file chartables.c was being created in the source directory
2545        instead of in the building directory. This caused the build to fail if the
2546        source directory was different from the building directory, and was
2547        read-only.
2548    
2549    18. Added some sample Win commands from Mark Tetrode into the NON-UNIX-USE
2550        file. No doubt somebody will tell me if they don't make sense... Also added
2551        Dan Mooney's comments about building on OpenVMS.
2552    
2553    19. Added support for partial matching via the PCRE_PARTIAL option for
2554        pcre_exec() and the \P data escape in pcretest.
2555    
2556    20. Extended pcretest with 3 new pattern features:
2557    
2558        (i)   A pattern option of the form ">rest-of-line" causes pcretest to
2559              write the compiled pattern to the file whose name is "rest-of-line".
2560              This is a straight binary dump of the data, with the saved pointer to
2561              the character tables forced to be NULL. The study data, if any, is
2562              written too. After writing, pcretest reads a new pattern.
2563    
2564        (ii)  If, instead of a pattern, "<rest-of-line" is given, pcretest reads a
2565              compiled pattern from the given file. There must not be any
2566              occurrences of "<" in the file name (pretty unlikely); if there are,
2567              pcretest will instead treat the initial "<" as a pattern delimiter.
2568              After reading in the pattern, pcretest goes on to read data lines as
2569              usual.
2570    
2571        (iii) The F pattern option causes pcretest to flip the bytes in the 32-bit
2572              and 16-bit fields in a compiled pattern, to simulate a pattern that
2573              was compiled on a host of opposite endianness.
2574    
2575    21. The pcre-exec() function can now cope with patterns that were compiled on
2576        hosts of opposite endianness, with this restriction:
2577    
2578          As for any compiled expression that is saved and used later, the tables
2579          pointer field cannot be preserved; the extra_data field in the arguments
2580          to pcre_exec() should be used to pass in a tables address if a value
2581          other than the default internal tables were used at compile time.
2582    
2583    22. Calling pcre_exec() with a negative value of the "ovecsize" parameter is
2584        now diagnosed as an error. Previously, most of the time, a negative number
2585        would have been treated as zero, but if in addition "ovector" was passed as
2586        NULL, a crash could occur.
2587    
2588    23. Updated the files ltmain.sh, config.sub, config.guess, and aclocal.m4 with
2589        new versions from the libtool 1.5 distribution (the last one is a copy of
2590        a file called libtool.m4). This seems to have fixed the need to patch
2591        "configure" to support Darwin 1.3 (which I used to do). However, I still
2592        had to patch ltmain.sh to ensure that ${SED} is set (it isn't on my
2593        workstation).
2594    
2595    24. Changed the PCRE licence to be the more standard "BSD" licence.
2596    
2597    
2598    Version 4.5 01-Dec-03
2599    ---------------------
2600    
2601     1. There has been some re-arrangement of the code for the match() function so
2602        that it can be compiled in a version that does not call itself recursively.
2603        Instead, it keeps those local variables that need separate instances for
2604        each "recursion" in a frame on the heap, and gets/frees frames whenever it
2605        needs to "recurse". Keeping track of where control must go is done by means
2606        of setjmp/longjmp. The whole thing is implemented by a set of macros that
2607        hide most of the details from the main code, and operates only if
2608        NO_RECURSE is defined while compiling pcre.c. If PCRE is built using the
2609        "configure" mechanism, "--disable-stack-for-recursion" turns on this way of
2610        operating.
2611    
2612        To make it easier for callers to provide specially tailored get/free
2613        functions for this usage, two new functions, pcre_stack_malloc, and
2614        pcre_stack_free, are used. They are always called in strict stacking order,
2615        and the size of block requested is always the same.
2616    
2617        The PCRE_CONFIG_STACKRECURSE info parameter can be used to find out whether
2618        PCRE has been compiled to use the stack or the heap for recursion. The
2619        -C option of pcretest uses this to show which version is compiled.
2620    
2621        A new data escape \S, is added to pcretest; it causes the amounts of store
2622        obtained and freed by both kinds of malloc/free at match time to be added
2623        to the output.
2624    
2625     2. Changed the locale test to use "fr_FR" instead of "fr" because that's
2626        what's available on my current Linux desktop machine.
2627    
2628     3. When matching a UTF-8 string, the test for a valid string at the start has
2629        been extended. If start_offset is not zero, PCRE now checks that it points
2630        to a byte that is the start of a UTF-8 character. If not, it returns
2631        PCRE_ERROR_BADUTF8_OFFSET (-11). Note: the whole string is still checked;
2632        this is necessary because there may be backward assertions in the pattern.
2633        When matching the same subject several times, it may save resources to use
2634        PCRE_NO_UTF8_CHECK on all but the first call if the string is long.
2635    
2636     4. The code for checking the validity of UTF-8 strings has been tightened so
2637        that it rejects (a) strings containing 0xfe or 0xff bytes and (b) strings
2638        containing "overlong sequences".
2639    
2640     5. Fixed a bug (appearing twice) that I could not find any way of exploiting!
2641        I had written "if ((digitab[*p++] && chtab_digit) == 0)" where the "&&"
2642        should have been "&", but it just so happened that all the cases this let
2643        through by mistake were picked up later in the function.
2644    
2645     6. I had used a variable called "isblank" - this is a C99 function, causing
2646        some compilers to warn. To avoid this, I renamed it (as "blankclass").
2647    
2648     7. Cosmetic: (a) only output another newline at the end of pcretest if it is
2649        prompting; (b) run "./pcretest /dev/null" at the start of the test script
2650        so the version is shown; (c) stop "make test" echoing "./RunTest".
2651    
2652     8. Added patches from David Burgess to enable PCRE to run on EBCDIC systems.
2653    
2654     9. The prototype for memmove() for systems that don't have it was using
2655        size_t, but the inclusion of the header that defines size_t was later. I've
2656        moved the #includes for the C headers earlier to avoid this.
2657    
2658    10. Added some adjustments to the code to make it easier to compiler on certain
2659        special systems:
2660    
2661          (a) Some "const" qualifiers were missing.
2662          (b) Added the macro EXPORT before all exported functions; by default this
2663              is defined to be empty.
2664          (c) Changed the dftables auxiliary program (that builds chartables.c) so
2665              that it reads its output file name as an argument instead of writing
2666              to the standard output and assuming this can be redirected.
2667    
2668    11. In UTF-8 mode, if a recursive reference (e.g. (?1)) followed a character
2669        class containing characters with values greater than 255, PCRE compilation
2670        went into a loop.
2671    
2672    12. A recursive reference to a subpattern that was within another subpattern
2673        that had a minimum quantifier of zero caused PCRE to crash. For example,
2674        (x(y(?2))z)? provoked this bug with a subject that got as far as the
2675        recursion. If the recursively-called subpattern itself had a zero repeat,
2676        that was OK.
2677    
2678    13. In pcretest, the buffer for reading a data line was set at 30K, but the
2679        buffer into which it was copied (for escape processing) was still set at
2680        1024, so long lines caused crashes.
2681    
2682    14. A pattern such as /[ab]{1,3}+/ failed to compile, giving the error
2683        "internal error: code overflow...". This applied to any character class
2684        that was followed by a possessive quantifier.
2685    
2686    15. Modified the Makefile to add libpcre.la as a prerequisite for
2687        libpcreposix.la because I was told this is needed for a parallel build to
2688        work.
2689    
2690    16. If a pattern that contained .* following optional items at the start was
2691        studied, the wrong optimizing data was generated, leading to matching
2692        errors. For example, studying /[ab]*.*c/ concluded, erroneously, that any
2693        matching string must start with a or b or c. The correct conclusion for
2694        this pattern is that a match can start with any character.
2695    
2696    
2697    Version 4.4 13-Aug-03
2698    ---------------------
2699    
2700     1. In UTF-8 mode, a character class containing characters with values between
2701        127 and 255 was not handled correctly if the compiled pattern was studied.
2702        In fixing this, I have also improved the studying algorithm for such
2703        classes (slightly).
2704    
2705     2. Three internal functions had redundant arguments passed to them. Removal
2706        might give a very teeny performance improvement.
2707    
2708     3. Documentation bug: the value of the capture_top field in a callout is *one
2709        more than* the number of the hightest numbered captured substring.
2710    
2711     4. The Makefile linked pcretest and pcregrep with -lpcre, which could result
2712        in incorrectly linking with a previously installed version. They now link
2713        explicitly with libpcre.la.
2714    
2715     5. configure.in no longer needs to recognize Cygwin specially.
2716    
2717     6. A problem in pcre.in for Windows platforms is fixed.
2718    
2719     7. If a pattern was successfully studied, and the -d (or /D) flag was given to
2720        pcretest, it used to include the size of the study block as part of its
2721        output. Unfortunately, the structure contains a field that has a different
2722        size on different hardware architectures. This meant that the tests that
2723        showed this size failed. As the block is currently always of a fixed size,
2724        this information isn't actually particularly useful in pcretest output, so
2725        I have just removed it.
2726    
2727     8. Three pre-processor statements accidentally did not start in column 1.
2728        Sadly, there are *still* compilers around that complain, even though
2729        standard C has not required this for well over a decade. Sigh.
2730    
2731     9. In pcretest, the code for checking callouts passed small integers in the
2732        callout_data field, which is a void * field. However, some picky compilers
2733        complained about the casts involved for this on 64-bit systems. Now
2734        pcretest passes the address of the small integer instead, which should get
2735        rid of the warnings.
2736    
2737    10. By default, when in UTF-8 mode, PCRE now checks for valid UTF-8 strings at
2738        both compile and run time, and gives an error if an invalid UTF-8 sequence
2739        is found. There is a option for disabling this check in cases where the
2740        string is known to be correct and/or the maximum performance is wanted.
2741    
2742    11. In response to a bug report, I changed one line in Makefile.in from
2743    
2744            -Wl,--out-implib,.libs/lib@WIN_PREFIX@pcreposix.dll.a \
2745        to
2746            -Wl,--out-implib,.libs/@WIN_PREFIX@libpcreposix.dll.a \
2747    
2748        to look similar to other lines, but I have no way of telling whether this
2749        is the right thing to do, as I do not use Windows. No doubt I'll get told
2750        if it's wrong...
2751    
2752    
2753    Version 4.3 21-May-03
2754    ---------------------
2755    
2756    1. Two instances of @WIN_PREFIX@ omitted from the Windows targets in the
2757       Makefile.
2758    
2759    2. Some refactoring to improve the quality of the code:
2760    
2761       (i)   The utf8_table... variables are now declared "const".
2762    
2763       (ii)  The code for \cx, which used the "case flipping" table to upper case
2764             lower case letters, now just substracts 32. This is ASCII-specific,
2765             but the whole concept of \cx is ASCII-specific, so it seems
2766             reasonable.
2767    
2768       (iii) PCRE was using its character types table to recognize decimal and
2769             hexadecimal digits in the pattern. This is silly, because it handles
2770             only 0-9, a-f, and A-F, but the character types table is locale-
2771             specific, which means strange things might happen. A private
2772             table is now used for this - though it costs 256 bytes, a table is
2773             much faster than multiple explicit tests. Of course, the standard
2774             character types table is still used for matching digits in subject
2775             strings against \d.
2776    
2777       (iv)  Strictly, the identifier ESC_t is reserved by POSIX (all identifiers
2778             ending in _t are). So I've renamed it as ESC_tee.
2779    
2780    3. The first argument for regexec() in the POSIX wrapper should have been
2781       defined as "const".
2782    
2783    4. Changed pcretest to use malloc() for its buffers so that they can be
2784       Electric Fenced for debugging.
2785    
2786    5. There were several places in the code where, in UTF-8 mode, PCRE would try
2787       to read one or more bytes before the start of the subject string. Often this
2788       had no effect on PCRE's behaviour, but in some circumstances it could
2789       provoke a segmentation fault.
2790    
2791    6. A lookbehind at the start of a pattern in UTF-8 mode could also cause PCRE
2792       to try to read one or more bytes before the start of the subject string.
2793    
2794    7. A lookbehind in a pattern matched in non-UTF-8 mode on a PCRE compiled with
2795       UTF-8 support could misbehave in various ways if the subject string
2796       contained bytes with the 0x80 bit set and the 0x40 bit unset in a lookbehind
2797       area. (PCRE was not checking for the UTF-8 mode flag, and trying to move
2798       back over UTF-8 characters.)
2799    
2800    
2801    Version 4.2 14-Apr-03
2802    ---------------------
2803    
2804    1. Typo "#if SUPPORT_UTF8" instead of "#ifdef SUPPORT_UTF8" fixed.
2805    
2806    2. Changes to the building process, supplied by Ronald Landheer-Cieslak
2807         [ON_WINDOWS]: new variable, "#" on non-Windows platforms
2808         [NOT_ON_WINDOWS]: new variable, "#" on Windows platforms
2809         [WIN_PREFIX]: new variable, "cyg" for Cygwin
2810         * Makefile.in: use autoconf substitution for OBJEXT, EXEEXT, BUILD_OBJEXT
2811           and BUILD_EXEEXT
2812         Note: automatic setting of the BUILD variables is not yet working
2813         set CPPFLAGS and BUILD_CPPFLAGS (but don't use yet) - should be used at
2814           compile-time but not at link-time
2815         [LINK]: use for linking executables only
2816         make different versions for Windows and non-Windows
2817         [LINKLIB]: new variable, copy of UNIX-style LINK, used for linking
2818           libraries
2819         [LINK_FOR_BUILD]: new variable
2820         [OBJEXT]: use throughout
2821         [EXEEXT]: use throughout
2822         <winshared>: new target
2823         <wininstall>: new target
2824         <dftables.o>: use native compiler
2825         <dftables>: use native linker
2826         <install>: handle Windows platform correctly
2827         <clean>: ditto
2828         <check>: ditto
2829         copy DLL to top builddir before testing
2830    
2831       As part of these changes, -no-undefined was removed again. This was reported
2832       to give trouble on HP-UX 11.0, so getting rid of it seems like a good idea
2833       in any case.
2834    
2835    3. Some tidies to get rid of compiler warnings:
2836    
2837       . In the match_data structure, match_limit was an unsigned long int, whereas
2838         match_call_count was an int. I've made them both unsigned long ints.
2839    
2840       . In pcretest the fact that a const uschar * doesn't automatically cast to
2841         a void * provoked a warning.
2842    
2843       . Turning on some more compiler warnings threw up some "shadow" variables
2844         and a few more missing casts.
2845    
2846    4. If PCRE was complied with UTF-8 support, but called without the PCRE_UTF8
2847       option, a class that contained a single character with a value between 128
2848       and 255 (e.g. /[\xFF]/) caused PCRE to crash.
2849    
2850    5. If PCRE was compiled with UTF-8 support, but called without the PCRE_UTF8
2851       option, a class that contained several characters, but with at least one
2852       whose value was between 128 and 255 caused PCRE to crash.
2853    
2854    
2855    Version 4.1 12-Mar-03
2856    ---------------------
2857    
2858    1. Compiling with gcc -pedantic found a couple of places where casts were
2859    needed, and a string in dftables.c that was longer than standard compilers are
2860    required to support.
2861    
2862    2. Compiling with Sun's compiler found a few more places where the code could
2863    be tidied up in order to avoid warnings.
2864    
2865    3. The variables for cross-compiling were called HOST_CC and HOST_CFLAGS; the
2866    first of these names is deprecated in the latest Autoconf in favour of the name
2867    CC_FOR_BUILD, because "host" is typically used to mean the system on which the
2868    compiled code will be run. I can't find a reference for HOST_CFLAGS, but by
2869    analogy I have changed it to CFLAGS_FOR_BUILD.
2870    
2871    4. Added -no-undefined to the linking command in the Makefile, because this is
2872    apparently helpful for Windows. To make it work, also added "-L. -lpcre" to the
2873    linking step for the pcreposix library.
2874    
2875    5. PCRE was failing to diagnose the case of two named groups with the same
2876    name.
2877    
2878    6. A problem with one of PCRE's optimizations was discovered. PCRE remembers a
2879    literal character that is needed in the subject for a match, and scans along to
2880    ensure that it is present before embarking on the full matching process. This
2881    saves time in cases of nested unlimited repeats that are never going to match.
2882    Problem: the scan can take a lot of time if the subject is very long (e.g.
2883    megabytes), thus penalizing straightforward matches. It is now done only if the
2884    amount of subject to be scanned is less than 1000 bytes.
2885    
2886    7. A lesser problem with the same optimization is that it was recording the
2887    first character of an anchored pattern as "needed", thus provoking a search
2888    right along the subject, even when the first match of the pattern was going to
2889    fail. The "needed" character is now not set for anchored patterns, unless it
2890    follows something in the pattern that is of non-fixed length. Thus, it still
2891    fulfils its original purpose of finding quick non-matches in cases of nested
2892    unlimited repeats, but isn't used for simple anchored patterns such as /^abc/.
2893    
2894    
2895    Version 4.0 17-Feb-03
2896    ---------------------
2897    
2898    1. If a comment in an extended regex that started immediately after a meta-item
2899    extended to the end of string, PCRE compiled incorrect data. This could lead to
2900    all kinds of weird effects. Example: /#/ was bad; /()#/ was bad; /a#/ was not.
2901    
2902    2. Moved to autoconf 2.53 and libtool 1.4.2.
2903    
2904    3. Perl 5.8 no longer needs "use utf8" for doing UTF-8 things. Consequently,
2905    the special perltest8 script is no longer needed - all the tests can be run
2906    from a single perltest script.
2907    
2908    4. From 5.004, Perl has not included the VT character (0x0b) in the set defined
2909    by \s. It has now been removed in PCRE. This means it isn't recognized as
2910    whitespace in /x regexes too, which is the same as Perl. Note that the POSIX
2911    class [:space:] *does* include VT, thereby creating a mess.
2912    
2913    5. Added the class [:blank:] (a GNU extension from Perl 5.8) to match only
2914    space and tab.
2915    
2916    6. Perl 5.005 was a long time ago. It's time to amalgamate the tests that use
2917    its new features into the main test script, reducing the number of scripts.
2918    
2919    7. Perl 5.8 has changed the meaning of patterns like /a(?i)b/. Earlier versions
2920    were backward compatible, and made the (?i) apply to the whole pattern, as if
2921    /i were given. Now it behaves more logically, and applies the option setting
2922    only to what follows. PCRE has been changed to follow suit. However, if it
2923    finds options settings right at the start of the pattern, it extracts them into
2924    the global options, as before. Thus, they show up in the info data.
2925    
2926    8. Added support for the \Q...\E escape sequence. Characters in between are
2927    treated as literals. This is slightly different from Perl in that $ and @ are
2928    also handled as literals inside the quotes. In Perl, they will cause variable
2929    interpolation. Note the following examples:
2930    
2931        Pattern            PCRE matches      Perl matches
2932    
2933        \Qabc$xyz\E        abc$xyz           abc followed by the contents of $xyz
2934        \Qabc\$xyz\E       abc\$xyz          abc\$xyz
2935        \Qabc\E\$\Qxyz\E   abc$xyz           abc$xyz
2936    
2937    For compatibility with Perl, \Q...\E sequences are recognized inside character
2938    classes as well as outside them.
2939    
2940    9. Re-organized 3 code statements in pcretest to avoid "overflow in
2941    floating-point constant arithmetic" warnings from a Microsoft compiler. Added a
2942    (size_t) cast to one statement in pcretest and one in pcreposix to avoid
2943    signed/unsigned warnings.
2944    
2945    10. SunOS4 doesn't have strtoul(). This was used only for unpicking the -o
2946    option for pcretest, so I've replaced it by a simple function that does just
2947    that job.
2948    
2949    11. pcregrep was ending with code 0 instead of 2 for the commands "pcregrep" or
2950    "pcregrep -".
2951    
2952    12. Added "possessive quantifiers" ?+, *+, ++, and {,}+ which come from Sun's
2953    Java package. This provides some syntactic sugar for simple cases of what my
2954    documentation calls "once-only subpatterns". A pattern such as x*+ is the same
2955    as (?>x*). In other words, if what is inside (?>...) is just a single repeated
2956    item, you can use this simplified notation. Note that only makes sense with
2957    greedy quantifiers. Consequently, the use of the possessive quantifier forces
2958    greediness, whatever the setting of the PCRE_UNGREEDY option.
2959    
2960    13. A change of greediness default within a pattern was not taking effect at
2961    the current level for patterns like /(b+(?U)a+)/. It did apply to parenthesized
2962    subpatterns that followed. Patterns like /b+(?U)a+/ worked because the option
2963    was abstracted outside.
2964    
2965    14. PCRE now supports the \G assertion. It is true when the current matching
2966    position is at the start point of the match. This differs from \A when the
2967    starting offset is non-zero. Used with the /g option of pcretest (or similar
2968    code), it works in the same way as it does for Perl's /g option. If all
2969    alternatives of a regex begin with \G, the expression is anchored to the start
2970    match position, and the "anchored" flag is set in the compiled expression.
2971    
2972    15. Some bugs concerning the handling of certain option changes within patterns
2973    have been fixed. These applied to options other than (?ims). For example,
2974    "a(?x: b c )d" did not match "XabcdY" but did match "Xa b c dY". It should have
2975    been the other way round. Some of this was related to change 7 above.
2976    
2977    16. PCRE now gives errors for /[.x.]/ and /[=x=]/ as unsupported POSIX
2978    features, as Perl does. Previously, PCRE gave the warnings only for /[[.x.]]/
2979    and /[[=x=]]/. PCRE now also gives an error for /[:name:]/ because it supports
2980    POSIX classes only within a class (e.g. /[[:alpha:]]/).
2981    
2982    17. Added support for Perl's \C escape. This matches one byte, even in UTF8
2983    mode. Unlike ".", it always matches newline, whatever the setting of
2984    PCRE_DOTALL. However, PCRE does not permit \C to appear in lookbehind
2985    assertions. Perl allows it, but it doesn't (in general) work because it can't
2986    calculate the length of the lookbehind. At least, that's the case for Perl
2987    5.8.0 - I've been told they are going to document that it doesn't work in
2988    future.
2989    
2990    18. Added an error diagnosis for escapes that PCRE does not support: these are
2991    \L, \l, \N, \P, \p, \U, \u, and \X.
2992    
2993    19. Although correctly diagnosing a missing ']' in a character class, PCRE was
2994    reading past the end of the pattern in cases such as /[abcd/.
2995    
2996    20. PCRE was getting more memory than necessary for patterns with classes that
2997    contained both POSIX named classes and other characters, e.g. /[[:space:]abc/.
2998    
2999    21. Added some code, conditional on #ifdef VPCOMPAT, to make life easier for
3000    compiling PCRE for use with Virtual Pascal.
3001    
3002    22. Small fix to the Makefile to make it work properly if the build is done
3003    outside the source tree.
3004    
3005    23. Added a new extension: a condition to go with recursion. If a conditional
3006    subpattern starts with (?(R) the "true" branch is used if recursion has
3007    happened, whereas the "false" branch is used only at the top level.
3008    
3009    24. When there was a very long string of literal characters (over 255 bytes
3010    without UTF support, over 250 bytes with UTF support), the computation of how
3011    much memory was required could be incorrect, leading to segfaults or other
3012    strange effects.
3013    
3014    25. PCRE was incorrectly assuming anchoring (either to start of subject or to
3015    start of line for a non-DOTALL pattern) when a pattern started with (.*) and
3016    there was a subsequent back reference to those brackets. This meant that, for
3017    example, /(.*)\d+\1/ failed to match "abc123bc". Unfortunately, it isn't
3018    possible to check for precisely this case. All we can do is abandon the
3019    optimization if .* occurs inside capturing brackets when there are any back
3020    references whatsoever. (See below for a better fix that came later.)
3021    
3022    26. The handling of the optimization for finding the first character of a
3023    non-anchored pattern, and for finding a character that is required later in the
3024    match were failing in some cases. This didn't break the matching; it just
3025    failed to optimize when it could. The way this is done has been re-implemented.
3026    
3027    27. Fixed typo in error message for invalid (?R item (it said "(?p").
3028    
3029    28. Added a new feature that provides some of the functionality that Perl
3030    provides with (?{...}). The facility is termed a "callout". The way it is done
3031    in PCRE is for the caller to provide an optional function, by setting
3032    pcre_callout to its entry point. Like pcre_malloc and pcre_free, this is a
3033    global variable. By default it is unset, which disables all calling out. To get
3034    the function called, the regex must include (?C) at appropriate points. This
3035    is, in fact, equivalent to (?C0), and any number <= 255 may be given with (?C).
3036    This provides a means of identifying different callout points. When PCRE
3037    reaches such a point in the regex, if pcre_callout has been set, the external
3038    function is called. It is provided with data in a structure called
3039    pcre_callout_block, which is defined in pcre.h. If the function returns 0,
3040    matching continues; if it returns a non-zero value, the match at the current
3041    point fails. However, backtracking will occur if possible. [This was changed
3042    later and other features added - see item 49 below.]
3043    
3044    29. pcretest is upgraded to test the callout functionality. It provides a
3045    callout function that displays information. By default, it shows the start of
3046    the match and the current position in the text. There are some new data escapes
3047    to vary what happens:
3048    
3049        \C+         in addition, show current contents of captured substrings
3050        \C-         do not supply a callout function
3051        \C!n        return 1 when callout number n is reached
3052        \C!n!m      return 1 when callout number n is reached for the mth time
3053    
3054    30. If pcregrep was called with the -l option and just a single file name, it
3055    output "<stdin>" if a match was found, instead of the file name.
3056    
3057    31. Improve the efficiency of the POSIX API to PCRE. If the number of capturing
3058    slots is less than POSIX_MALLOC_THRESHOLD, use a block on the stack to pass to
3059    pcre_exec(). This saves a malloc/free per call. The default value of
3060    POSIX_MALLOC_THRESHOLD is 10; it can be changed by --with-posix-malloc-threshold
3061    when configuring.
3062    
3063    32. The default maximum size of a compiled pattern is 64K. There have been a
3064    few cases of people hitting this limit. The code now uses macros to handle the
3065    storing of links as offsets within the compiled pattern. It defaults to 2-byte
3066    links, but this can be changed to 3 or 4 bytes by --with-link-size when
3067    configuring. Tests 2 and 5 work only with 2-byte links because they output
3068    debugging information about compiled patterns.
3069    
3070    33. Internal code re-arrangements:
3071    
3072    (a) Moved the debugging function for printing out a compiled regex into
3073        its own source file (printint.c) and used #include to pull it into
3074        pcretest.c and, when DEBUG is defined, into pcre.c, instead of having two
3075        separate copies.
3076    
3077    (b) Defined the list of op-code names for debugging as a macro in
3078        internal.h so that it is next to the definition of the opcodes.
3079    
3080    (c) Defined a table of op-code lengths for simpler skipping along compiled
3081        code. This is again a macro in internal.h so that it is next to the
3082        definition of the opcodes.
3083    
3084    34. Added support for recursive calls to individual subpatterns, along the
3085    lines of Robin Houston's patch (but implemented somewhat differently).
3086    
3087    35. Further mods to the Makefile to help Win32. Also, added code to pcregrep to
3088    allow it to read and process whole directories in Win32. This code was
3089    contributed by Lionel Fourquaux; it has not been tested by me.
3090    
3091    36. Added support for named subpatterns. The Python syntax (?P<name>...) is
3092    used to name a group. Names consist of alphanumerics and underscores, and must
3093    be unique. Back references use the syntax (?P=name) and recursive calls use
3094    (?P>name) which is a PCRE extension to the Python extension. Groups still have
3095    numbers. The function pcre_fullinfo() can be used after compilation to extract
3096    a name/number map. There are three relevant calls:
3097    
3098      PCRE_INFO_NAMEENTRYSIZE        yields the size of each entry in the map
3099      PCRE_INFO_NAMECOUNT            yields the number of entries
3100      PCRE_INFO_NAMETABLE            yields a pointer to the map.
3101    
3102    The map is a vector of fixed-size entries. The size of each entry depends on
3103    the length of the longest name used. The first two bytes of each entry are the
3104    group number, most significant byte first. There follows the corresponding
3105    name, zero terminated. The names are in alphabetical order.
3106    
3107    37. Make the maximum literal string in the compiled code 250 for the non-UTF-8
3108    case instead of 255. Making it the same both with and without UTF-8 support
3109    means that the same test output works with both.
3110    
3111    38. There was a case of malloc(0) in the POSIX testing code in pcretest. Avoid
3112    calling malloc() with a zero argument.
3113    
3114    39. Change 25 above had to resort to a heavy-handed test for the .* anchoring
3115    optimization. I've improved things by keeping a bitmap of backreferences with
3116    numbers 1-31 so that if .* occurs inside capturing brackets that are not in
3117    fact referenced, the optimization can be applied. It is unlikely that a
3118    relevant occurrence of .* (i.e. one which might indicate anchoring or forcing
3119    the match to follow \n) will appear inside brackets with a number greater than
3120    31, but if it does, any back reference > 31 suppresses the optimization.
3121    
3122    40. Added a new compile-time option PCRE_NO_AUTO_CAPTURE. This has the effect
3123    of disabling numbered capturing parentheses. Any opening parenthesis that is
3124    not followed by ? behaves as if it were followed by ?: but named parentheses
3125    can still be used for capturing (and they will acquire numbers in the usual
3126    way).
3127    
3128    41. Redesigned the return codes from the match() function into yes/no/error so
3129    that errors can be passed back from deep inside the nested calls. A malloc
3130    failure while inside a recursive subpattern call now causes the
3131    PCRE_ERROR_NOMEMORY return instead of quietly going wrong.
3132    
3133    42. It is now possible to set a limit on the number of times the match()
3134    function is called in a call to pcre_exec(). This facility makes it possible to
3135    limit the amount of recursion and backtracking, though not in a directly
3136    obvious way, because the match() function is used in a number of different
3137    circumstances. The count starts from zero for each position in the subject
3138    string (for non-anchored patterns). The default limit is, for compatibility, a
3139    large number, namely 10 000 000. You can change this in two ways:
3140    
3141    (a) When configuring PCRE before making, you can use --with-match-limit=n
3142        to set a default value for the compiled library.
3143    
3144    (b) For each call to pcre_exec(), you can pass a pcre_extra block in which
3145        a different value is set. See 45 below.
3146    
3147    If the limit is exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT.
3148    
3149    43. Added a new function pcre_config(int, void *) to enable run-time extraction
3150    of things that can be changed at compile time. The first argument specifies
3151    what is wanted and the second points to where the information is to be placed.
3152    The current list of available information is:
3153    
3154      PCRE_CONFIG_UTF8
3155    
3156    The output is an integer that is set to one if UTF-8 support is available;
3157    otherwise it is set to zero.
3158    
3159      PCRE_CONFIG_NEWLINE
3160    
3161    The output is an integer that it set to the value of the code that is used for
3162    newline. It is either LF (10) or CR (13).
3163    
3164      PCRE_CONFIG_LINK_SIZE
3165    
3166    The output is an integer that contains the number of bytes used for internal
3167    linkage in compiled expressions. The value is 2, 3, or 4. See item 32 above.
3168    
3169      PCRE_CONFIG_POSIX_MALLOC_THRESHOLD
3170    
3171    The output is an integer that contains the threshold above which the POSIX
3172    interface uses malloc() for output vectors. See item 31 above.
3173    
3174      PCRE_CONFIG_MATCH_LIMIT
3175    
3176    The output is an unsigned integer that contains the default limit of the number
3177    of match() calls in a pcre_exec() execution. See 42 above.
3178    
3179    44. pcretest has been upgraded by the addition of the -C option. This causes it
3180    to extract all the available output from the new pcre_config() function, and to
3181    output it. The program then exits immediately.
3182    
3183    45. A need has arisen to pass over additional data with calls to pcre_exec() in
3184    order to support additional features. One way would have been to define
3185    pcre_exec2() (for example) with extra arguments, but this would not have been
3186    extensible, and would also have required all calls to the original function to
3187    be mapped to the new one. Instead, I have chosen to extend the mechanism that
3188    is used for passing in "extra" data from pcre_study().
3189    
3190    The pcre_extra structure is now exposed and defined in pcre.h. It currently
3191    contains the following fields:
3192    
3193      flags         a bitmap indicating which of the following fields are set
3194      study_data    opaque data from pcre_study()
3195      match_limit   a way of specifying a limit on match() calls for a specific
3196                      call to pcre_exec()
3197      callout_data  data for callouts (see 49 below)
3198    
3199    The flag bits are also defined in pcre.h, and are
3200    
3201      PCRE_EXTRA_STUDY_DATA
3202      PCRE_EXTRA_MATCH_LIMIT
3203      PCRE_EXTRA_CALLOUT_DATA
3204    
3205    The pcre_study() function now returns one of these new pcre_extra blocks, with
3206    the actual study data pointed to by the study_data field, and the
3207    PCRE_EXTRA_STUDY_DATA flag set. This can be passed directly to pcre_exec() as
3208    before. That is, this change is entirely upwards-compatible and requires no
3209    change to existing code.
3210    
3211    If you want to pass in additional data to pcre_exec(), you can either place it
3212    in a pcre_extra block provided by pcre_study(), or create your own pcre_extra
3213    block.
3214    
3215    46. pcretest has been extended to test the PCRE_EXTRA_MATCH_LIMIT feature. If a
3216    data string contains the escape sequence \M, pcretest calls pcre_exec() several
3217    times with different match limits, until it finds the minimum value needed for
3218    pcre_exec() to complete. The value is then output. This can be instructive; for
3219    most simple matches the number is quite small, but for pathological cases it
3220    gets very large very quickly.
3221    
3222    47. There's a new option for pcre_fullinfo() called PCRE_INFO_STUDYSIZE. It
3223    returns the size of the data block pointed to by the study_data field in a
3224    pcre_extra block, that is, the value that was passed as the argument to
3225    pcre_malloc() when PCRE was getting memory in which to place the information
3226    created by pcre_study(). The fourth argument should point to a size_t variable.
3227    pcretest has been extended so that this information is shown after a successful
3228    pcre_study() call when information about the compiled regex is being displayed.
3229    
3230    48. Cosmetic change to Makefile: there's no need to have / after $(DESTDIR)
3231    because what follows is always an absolute path. (Later: it turns out that this
3232    is more than cosmetic for MinGW, because it doesn't like empty path
3233    components.)
3234    
3235    49. Some changes have been made to the callout feature (see 28 above):
3236    
3237    (i)  A callout function now has three choices for what it returns:
3238    
3239           0  =>  success, carry on matching
3240         > 0  =>  failure at this point, but backtrack if possible
3241         < 0  =>  serious error, return this value from pcre_exec()
3242    
3243         Negative values should normally be chosen from the set of PCRE_ERROR_xxx
3244         values. In particular, returning PCRE_ERROR_NOMATCH forces a standard
3245         "match failed" error. The error number PCRE_ERROR_CALLOUT is reserved for
3246         use by callout functions. It will never be used by PCRE itself.
3247    
3248    (ii) The pcre_extra structure (see 45 above) has a void * field called
3249         callout_data, with corresponding flag bit PCRE_EXTRA_CALLOUT_DATA. The
3250         pcre_callout_block structure has a field of the same name. The contents of
3251         the field passed in the pcre_extra structure are passed to the callout
3252         function in the corresponding field in the callout block. This makes it
3253         easier to use the same callout-containing regex from multiple threads. For
3254         testing, the pcretest program has a new data escape
3255    
3256           \C*n        pass the number n (may be negative) as callout_data
3257    
3258         If the callout function in pcretest receives a non-zero value as
3259         callout_data, it returns that value.
3260    
3261    50. Makefile wasn't handling CFLAGS properly when compiling dftables. Also,
3262    there were some redundant $(CFLAGS) in commands that are now specified as
3263    $(LINK), which already includes $(CFLAGS).
3264    
3265    51. Extensions to UTF-8 support are listed below. These all apply when (a) PCRE
3266    has been compiled with UTF-8 support *and* pcre_compile() has been compiled
3267    with the PCRE_UTF8 flag. Patterns that are compiled without that flag assume
3268    one-byte characters throughout. Note that case-insensitive matching applies
3269    only to characters whose values are less than 256. PCRE doesn't support the
3270    notion of cases for higher-valued characters.
3271    
3272    (i)   A character class whose characters are all within 0-255 is handled as
3273          a bit map, and the map is inverted for negative classes. Previously, a
3274          character > 255 always failed to match such a class; however it should
3275          match if the class was a negative one (e.g. [^ab]). This has been fixed.
3276    
3277    (ii)  A negated character class with a single character < 255 is coded as
3278          "not this character" (OP_NOT). This wasn't working properly when the test
3279          character was multibyte, either singly or repeated.
3280    
3281    (iii) Repeats of multibyte characters are now handled correctly in UTF-8
3282          mode, for example: \x{100}{2,3}.
3283    
3284    (iv)  The character escapes \b, \B, \d, \D, \s, \S, \w, and \W (either
3285          singly or repeated) now correctly test multibyte characters. However,
3286          PCRE doesn't recognize any characters with values greater than 255 as
3287          digits, spaces, or word characters. Such characters always match \D, \S,
3288          and \W, and never match \d, \s, or \w.
3289    
3290    (v)   Classes may now contain characters and character ranges with values
3291          greater than 255. For example: [ab\x{100}-\x{400}].
3292    
3293    (vi)  pcregrep now has a --utf-8 option (synonym -u) which makes it call
3294          PCRE in UTF-8 mode.
3295    
3296    52. The info request value PCRE_INFO_FIRSTCHAR has been renamed
3297    PCRE_INFO_FIRSTBYTE because it is a byte value. However, the old name is
3298    retained for backwards compatibility. (Note that LASTLITERAL is also a byte
3299    value.)
3300    
3301    53. The single man page has become too large. I have therefore split it up into
3302    a number of separate man pages. These also give rise to individual HTML pages;
3303    these are now put in a separate directory, and there is an index.html page that
3304    lists them all. Some hyperlinking between the pages has been installed.
3305    
3306    54. Added convenience functions for handling named capturing parentheses.
3307    
3308    55. Unknown escapes inside character classes (e.g. [\M]) and escapes that
3309    aren't interpreted therein (e.g. [\C]) are literals in Perl. This is now also
3310    true in PCRE, except when the PCRE_EXTENDED option is set, in which case they
3311    are faulted.
3312    
3313    56. Introduced HOST_CC and HOST_CFLAGS which can be set in the environment when
3314    calling configure. These values are used when compiling the dftables.c program
3315    which is run to generate the source of the default character tables. They
3316    default to the values of CC and CFLAGS. If you are cross-compiling PCRE,
3317    you will need to set these values.
3318    
3319    57. Updated the building process for Windows DLL, as provided by Fred Cox.
3320    
3321    
3322    Version 3.9 02-Jan-02
3323    ---------------------
3324    
3325    1. A bit of extraneous text had somehow crept into the pcregrep documentation.
3326    
3327    2. If --disable-static was given, the building process failed when trying to
3328    build pcretest and pcregrep. (For some reason it was using libtool to compile
3329    them, which is not right, as they aren't part of the library.)
3330    
3331    
3332    Version 3.8 18-Dec-01
3333    ---------------------
3334    
3335    1. The experimental UTF-8 code was completely screwed up. It was packing the
3336    bytes in the wrong order. How dumb can you get?
3337    
3338    
3339    Version 3.7 29-Oct-01
3340    ---------------------
3341    
3342    1. In updating pcretest to check change 1 of version 3.6, I screwed up.
3343    This caused pcretest, when used on the test data, to segfault. Unfortunately,
3344    this didn't happen under Solaris 8, where I normally test things.
3345    
3346    2. The Makefile had to be changed to make it work on BSD systems, where 'make'
3347    doesn't seem to recognize that ./xxx and xxx are the same file. (This entry
3348    isn't in ChangeLog distributed with 3.7 because I forgot when I hastily made
3349    this fix an hour or so after the initial 3.7 release.)
3350    
3351    
3352    Version 3.6 23-Oct-01
3353    ---------------------
3354    
3355    1. Crashed with /(sens|respons)e and \1ibility/ and "sense and sensibility" if
3356    offsets passed as NULL with zero offset count.
3357    
3358    2. The config.guess and config.sub files had not been updated when I moved to
3359    the latest autoconf.
3360    
3361    
3362    Version 3.5 15-Aug-01
3363    ---------------------
3364    
3365    1. Added some missing #if !defined NOPOSIX conditionals in pcretest.c that
3366    had been forgotten.
3367    
3368    2. By using declared but undefined structures, we can avoid using "void"
3369    definitions in pcre.h while keeping the internal definitions of the structures
3370    private.
3371    
3372    3. The distribution is now built using autoconf 2.50 and libtool 1.4. From a
3373    user point of view, this means that both static and shared libraries are built
3374    by default, but this can be individually controlled. More of the work of
3375    handling this static/shared cases is now inside libtool instead of PCRE's make
3376    file.
3377    
3378    4. The pcretest utility is now installed along with pcregrep because it is
3379    useful for users (to test regexs) and by doing this, it automatically gets
3380    relinked by libtool. The documentation has been turned into a man page, so
3381    there are now .1, .txt, and .html versions in /doc.
3382    
3383    5. Upgrades to pcregrep:
3384       (i)   Added long-form option names like gnu grep.
3385       (ii)  Added --help to list all options with an explanatory phrase.
3386       (iii) Added -r, --recursive to recurse into sub-directories.
3387       (iv)  Added -f, --file to read patterns from a file.
3388    
3389    6. pcre_exec() was referring to its "code" argument before testing that
3390    argument for NULL (and giving an error if it was NULL).
3391    
3392    7. Upgraded Makefile.in to allow for compiling in a different directory from
3393    the source directory.
3394    
3395    8. Tiny buglet in pcretest: when pcre_fullinfo() was called to retrieve the
3396    options bits, the pointer it was passed was to an int instead of to an unsigned
3397    long int. This mattered only on 64-bit systems.
3398    
3399    9. Fixed typo (3.4/1) in pcre.h again. Sigh. I had changed pcre.h (which is
3400    generated) instead of pcre.in, which it its source. Also made the same change
3401    in several of the .c files.
3402    
3403    10. A new release of gcc defines printf() as a macro, which broke pcretest
3404    because it had an ifdef in the middle of a string argument for printf(). Fixed
3405    by using separate calls to printf().
3406    
3407    11. Added --enable-newline-is-cr and --enable-newline-is-lf to the configure
3408    script, to force use of CR or LF instead of \n in the source. On non-Unix
3409    systems, the value can be set in config.h.
3410    
3411    12. The limit of 200 on non-capturing parentheses is a _nesting_ limit, not an
3412    absolute limit. Changed the text of the error message to make this clear, and
3413    likewise updated the man page.
3414    
3415    13. The limit of 99 on the number of capturing subpatterns has been removed.
3416    The new limit is 65535, which I hope will not be a "real" limit.
3417    
3418    
3419    Version 3.4 22-Aug-00
3420    ---------------------
3421    
3422    1. Fixed typo in pcre.h: unsigned const char * changed to const unsigned char *.
3423    
3424    2. Diagnose condition (?(0) as an error instead of crashing on matching.
3425    
3426    
3427    Version 3.3 01-Aug-00
3428    ---------------------
3429    
3430    1. If an octal character was given, but the value was greater than \377, it
3431    was not getting masked to the least significant bits, as documented. This could
3432    lead to crashes in some systems.
3433    
3434    2. Perl 5.6 (if not earlier versions) accepts classes like [a-\d] and treats
3435    the hyphen as a literal. PCRE used to give an error; it now behaves like Perl.
3436    
3437    3. Added the functions pcre_free_substring() and pcre_free_substring_list().
3438    These just pass their arguments on to (pcre_free)(), but they are provided
3439    because some uses of PCRE bind it to non-C systems that can call its functions,
3440    but cannot call free() or pcre_free() directly.
3441    
3442    4. Add "make test" as a synonym for "make check". Corrected some comments in
3443    the Makefile.
3444    
3445    5. Add $(DESTDIR)/ in front of all the paths in the "install" target in the
3446    Makefile.
3447    
3448    6. Changed the name of pgrep to pcregrep, because Solaris has introduced a
3449    command called pgrep for grepping around the active processes.
3450    
3451    7. Added the beginnings of support for UTF-8 character strings.
3452    
3453    8. Arranged for the Makefile to pass over the settings of CC, CFLAGS, and
3454    RANLIB to ./ltconfig so that they are used by libtool. I think these are all
3455    the relevant ones. (AR is not passed because ./ltconfig does its own figuring
3456    out for the ar command.)
3457    
3458    
3459    Version 3.2 12-May-00
3460    ---------------------
3461    
3462    This is purely a bug fixing release.
3463    
3464    1. If the pattern /((Z)+|A)*/ was matched agained ZABCDEFG it matched Z instead
3465    of ZA. This was just one example of several cases that could provoke this bug,
3466    which was introduced by change 9 of version 2.00. The code for breaking
3467    infinite loops after an iteration that matches an empty string was't working
3468    correctly.
3469    
3470    2. The pcretest program was not imitating Perl correctly for the pattern /a*/g
3471    when matched against abbab (for example). After matching an empty string, it
3472    wasn't forcing anchoring when setting PCRE_NOTEMPTY for the next attempt; this
3473    caused it to match further down the string than it should.
3474    
3475    3. The code contained an inclusion of sys/types.h. It isn't clear why this
3476    was there because it doesn't seem to be needed, and it causes trouble on some
3477    systems, as it is not a Standard C header. It has been removed.
3478    
3479    4. Made 4 silly changes to the source to avoid stupid compiler warnings that
3480    were reported on the Macintosh. The changes were from
3481    
3482      while ((c = *(++ptr)) != 0 && c != '\n');
3483    to
3484      while ((c = *(++ptr)) != 0 && c != '\n') ;
3485    
3486    Totally extraordinary, but if that's what it takes...
3487    
3488    5. PCRE is being used in one environment where neither memmove() nor bcopy() is
3489    available. Added HAVE_BCOPY and an autoconf test for it; if neither
3490    HAVE_MEMMOVE nor HAVE_BCOPY is set, use a built-in emulation function which
3491    assumes the way PCRE uses memmove() (always moving upwards).
3492    
3493    6. PCRE is being used in one environment where strchr() is not available. There
3494    was only one use in pcre.c, and writing it out to avoid strchr() probably gives
3495    faster code anyway.
3496    
3497    
3498    Version 3.1 09-Feb-00
3499    ---------------------
3500    
3501    The only change in this release is the fixing of some bugs in Makefile.in for
3502    the "install" target:
3503    
3504    (1) It was failing to install pcreposix.h.
3505    
3506    (2) It was overwriting the pcre.3 man page with the pcreposix.3 man page.
3507    
3508    
3509    Version 3.0 01-Feb-00
3510    ---------------------
3511    
3512    1. Add support for the /+ modifier to perltest (to output $` like it does in
3513    pcretest).
3514    
3515    2. Add support for the /g modifier to perltest.
3516    
3517    3. Fix pcretest so that it behaves even more like Perl for /g when the pattern
3518    matches null strings.
3519    
3520    4. Fix perltest so that it doesn't do unwanted things when fed an empty
3521    pattern. Perl treats empty patterns specially - it reuses the most recent
3522    pattern, which is not what we want. Replace // by /(?#)/ in order to avoid this
3523    effect.
3524    
3525    5. The POSIX interface was broken in that it was just handing over the POSIX
3526    captured string vector to pcre_exec(), but (since release 2.00) PCRE has
3527    required a bigger vector, with some working space on the end. This means that
3528    the POSIX wrapper now has to get and free some memory, and copy the results.
3529    
3530    6. Added some simple autoconf support, placing the test data and the
3531    documentation in separate directories, re-organizing some of the
3532    information files, and making it build pcre-config (a GNU standard). Also added
3533    libtool support for building PCRE as a shared library, which is now the
3534    default.
3535    
3536    7. Got rid of the leading zero in the definition of PCRE_MINOR because 08 and
3537    09 are not valid octal constants. Single digits will be used for minor values
3538    less than 10.
3539    
3540    8. Defined REG_EXTENDED and REG_NOSUB as zero in the POSIX header, so that
3541    existing programs that set these in the POSIX interface can use PCRE without
3542    modification.
3543    
3544    9. Added a new function, pcre_fullinfo() with an extensible interface. It can
3545    return all that pcre_info() returns, plus additional data. The pcre_info()
3546    function is retained for compatibility, but is considered to be obsolete.
3547    
3548    10. Added experimental recursion feature (?R) to handle one common case that
3549    Perl 5.6 will be able to do with (?p{...}).
3550    
3551    11. Added support for POSIX character classes like [:alpha:], which Perl is
3552    adopting.
3553    
3554    
3555    Version 2.08 31-Aug-99
3556    ----------------------
3557    
3558    1. When startoffset was not zero and the pattern began with ".*", PCRE was not
3559    trying to match at the startoffset position, but instead was moving forward to
3560    the next newline as if a previous match had failed.
3561    
3562    2. pcretest was not making use of PCRE_NOTEMPTY when repeating for /g and /G,
3563    and could get into a loop if a null string was matched other than at the start
3564    of the subject.
3565    
3566    3. Added definitions of PCRE_MAJOR and PCRE_MINOR to pcre.h so the version can
3567    be distinguished at compile time, and for completeness also added PCRE_DATE.
3568    
3569    5. Added Paul Sokolovsky's minor changes to make it easy to compile a Win32 DLL
3570    in GnuWin32 environments.
3571    
3572    
3573    Version 2.07 29-Jul-99
3574    ----------------------
3575    
3576    1. The documentation is now supplied in plain text form and HTML as well as in
3577    the form of man page sources.
3578    
3579    2. C++ compilers don't like assigning (void *) values to other pointer types.
3580    In particular this affects malloc(). Although there is no problem in Standard
3581    C, I've put in casts to keep C++ compilers happy.
3582    
3583    3. Typo on pcretest.c; a cast of (unsigned char *) in the POSIX regexec() call
3584    should be (const char *).
3585    
3586    4. If NOPOSIX is defined, pcretest.c compiles without POSIX support. This may
3587    be useful for non-Unix systems who don't want to bother with the POSIX stuff.
3588    However, I haven't made this a standard facility. The documentation doesn't
3589    mention it, and the Makefile doesn't support it.
3590    
3591    5. The Makefile now contains an "install" target, with editable destinations at
3592    the top of the file. The pcretest program is not installed.
3593    
3594    6. pgrep -V now gives the PCRE version number and date.
3595    
3596    7. Fixed bug: a zero repetition after a literal string (e.g. /abcde{0}/) was
3597    causing the entire string to be ignored, instead of just the last character.
3598    
3599    8. If a pattern like /"([^\\"]+|\\.)*"/ is applied in the normal way to a
3600    non-matching string, it can take a very, very long time, even for strings of
3601    quite modest length, because of the nested recursion. PCRE now does better in
3602    some of these cases. It does this by remembering the last required literal
3603    character in the pattern, and pre-searching the subject to ensure it is present
3604    before running the real match. In other words, it applies a heuristic to detect
3605    some types of certain failure quickly, and in the above example, if presented
3606    with a string that has no trailing " it gives "no match" very quickly.
3607    
3608    9. A new runtime option PCRE_NOTEMPTY causes null string matches to be ignored;
3609    other alternatives are tried instead.
3610    
3611    
3612  Version 2.06 09-Jun-99  Version 2.06 09-Jun-99
3613  ----------------------  ----------------------

Legend:
Removed from v.35  
changed lines
  Added in v.573

  ViewVC Help
Powered by ViewVC 1.1.5