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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
4    Version 7.1 24-Apr-07
5    ---------------------
7     1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
8        that is more "standard", making use of automake and other Autotools. There
9        is some re-arrangement of the files and adjustment of comments consequent
10        on this.
12     2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
13        for recursive directory scanning broke on some systems because the files
14        are not scanned in any specific order and on different systems the order
15        was different. A call to "sort" has been inserted into RunGrepTest for the
16        approprate test as a short-term fix. In the longer term there may be an
17        alternative.
19     3. I had an email from Eric Raymond about problems translating some of PCRE's
20        man pages to HTML (despite the fact that I distribute HTML pages, some
21        people do their own conversions for various reasons). The problems
22        concerned the use of low-level troff macros .br and .in. I have therefore
23        removed all such uses from the man pages (some were redundant, some could
24        be replaced by .nf/.fi pairs). The 132html script that I use to generate
25        HTML has been updated to handle .nf/.fi and to complain if it encounters
26        .br or .in.
28     4. Updated comments in configure.ac that get placed in config.h.in and also
29        arranged for config.h to be included in the distribution, with the name
30        config.h.generic, for the benefit of those who have to compile without
31        Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
33     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
34        Weber: (1) pcre_internal.h was missing some function renames; (2) updated
35        makevp.bat for the current PCRE, using the additional files
36        makevp_c.txt, makevp_l.txt, and pcregexp.pas.
38     6. A Windows user reported a minor discrepancy with test 2, which turned out
39        to be caused by a trailing space on an input line that had got lost in his
40        copy. The trailing space was an accident, so I've just removed it.
42     7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
43        that is needed.
45     8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
46        as "const" (a) because they are and (b) because it helps the PHP
47        maintainers who have recently made a script to detect big data structures
48        in the php code that should be moved to the .rodata section. I remembered
49        to update Builducptable as well, so it won't revert if ucptable.h is ever
50        re-created.
52     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
53        pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
54        order to be able to cut out the UTF-8 tables in the latter when UTF-8
55        support is not required. This saves 1.5-2K of code, which is important in
56        some applications.
58        Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
59        so as not to refer to the tables, even though these functions will never be
60        called when UTF-8 support is disabled. Otherwise there are problems with a
61        shared library.
63    10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
65        (a) It was defining its arguments as char * instead of void *.
67        (b) It was assuming that all moves were upwards in memory; this was true
68            a long time ago when I wrote it, but is no longer the case.
70        The emulated memove() is provided for those environments that have neither
71        memmove() nor bcopy(). I didn't think anyone used it these days, but that
72        is clearly not the case, as these two bugs were recently reported.
74    11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
75        and Detrail to create the HTML documentation, the .txt form of the man
76        pages, and it removes trailing spaces from listed files. It also creates
77        pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
78        case, it wraps all the #defines with #ifndefs. This script should be run
79        before "make dist".
81    12. Fixed two fairly obscure bugs concerned with quantified caseless matching
82        with Unicode property support.
84        (a) For a maximizing quantifier, if the two different cases of the
85            character were of different lengths in their UTF-8 codings (there are
86            some cases like this - I found 11), and the matching function had to
87            back up over a mixture of the two cases, it incorrectly assumed they
88            were both the same length.
90        (b) When PCRE was configured to use the heap rather than the stack for
91            recursion during matching, it was not correctly preserving the data for
92            the other case of a UTF-8 character when checking ahead for a match
93            while processing a minimizing repeat. If the check also involved
94            matching a wide character, but failed, corruption could cause an
95            erroneous result when trying to check for a repeat of the original
96            character.
98    13. Some tidying changes to the testing mechanism:
100        (a) The RunTest script now detects the internal link size and whether there
101            is UTF-8 and UCP support by running ./pcretest -C instead of relying on
102            values substituted by "configure". (The RunGrepTest script already did
103            this for UTF-8.) The configure.ac script no longer substitutes the
104            relevant variables.
106        (b) The debugging options /B and /D in pcretest show the compiled bytecode
107            with length and offset values. This means that the output is different
108            for different internal link sizes. Test 2 is skipped for link sizes
109            other than 2 because of this, bypassing the problem. Unfortunately,
110            there was also a test in test 3 (the locale tests) that used /B and
111            failed for link sizes other than 2. Rather than cut the whole test out,
112            I have added a new /Z option to pcretest that replaces the length and
113            offset values with spaces. This is now used to make test 3 independent
114            of link size. (Test 2 will be tidied up later.)
116    14. If erroroffset was passed as NULL to pcre_compile, it provoked a
117        segmentation fault instead of returning the appropriate error message.
119    15. In multiline mode when the newline sequence was set to "any", the pattern
120        ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
121        This doesn't seem right; it now treats the CRLF combination as the line
122        ending, and so does not match in that case. It's only a pattern such as ^$
123        that would hit this one: something like ^ABC$ would have failed after \r
124        and then tried again after \r\n.
126    16. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
127        in an attempt to make files that differ only in their line terminators
128        compare equal. This works on Linux.
130    17. Under certain error circumstances pcregrep might try to free random memory
131        as it exited. This is now fixed, thanks to valgrind.
133    19. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
134        "abc\r\n\r\n", it found an unwanted second match after the second \r. This
135        was because its rules for how to advance for /g after matching an empty
136        string at the end of a line did not allow for this case. They now check for
137        it specially.
139    20. pcretest is supposed to handle patterns and data of any length, by
140        extending its buffers when necessary. It was getting this wrong when the
141        buffer for a data line had to be extended.
143    21. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or
144        CRLF as a newline sequence.
146    22. Code for handling Unicode properties in pcre_dfa_exec() wasn't being cut
147        out by #ifdef SUPPORT_UCP. This did no harm, as it could never be used, but
148        I have nevertheless tidied it up.
150    23. Added some casts to kill warnings from HP-UX ia64 compiler.
152    24. Added a man page for pcre-config.
155    Version 7.0 19-Dec-06
156    ---------------------
158     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
159        moving to gcc 4.1.1.
161     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
162        sys/time.h, which is documented as needed for this function. It doesn't
163        seem to matter on Linux, but it showed up on some releases of OS X.
165     3. It seems that there are systems where bytes whose values are greater than
166        127 match isprint() in the "C" locale. The "C" locale should be the
167        default when a C program starts up. In most systems, only ASCII printing
168        characters match isprint(). This difference caused the output from pcretest
169        to vary, making some of the tests fail. I have changed pcretest so that:
171        (a) When it is outputting text in the compiled version of a pattern, bytes
172            other than 32-126 are always shown as hex escapes.
174        (b) When it is outputting text that is a matched part of a subject string,
175            it does the same, unless a different locale has been set for the match
176            (using the /L modifier). In this case, it uses isprint() to decide.
178     4. Fixed a major bug that caused incorrect computation of the amount of memory
179        required for a compiled pattern when options that changed within the
180        pattern affected the logic of the preliminary scan that determines the
181        length. The relevant options are -x, and -i in UTF-8 mode. The result was
182        that the computed length was too small. The symptoms of this bug were
183        either the PCRE error "internal error: code overflow" from pcre_compile(),
184        or a glibc crash with a message such as "pcretest: free(): invalid next
185        size (fast)". Examples of patterns that provoked this bug (shown in
186        pcretest format) are:
188          /(?-x: )/x
189          /(?x)(?-x: \s*#\s*)/
190          /((?i)[\x{c0}])/8
191          /(?i:[\x{c0}])/8
193        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
194        is now done differently.
196     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
197        wrapper classes; (b) implement a new function in the C++ scanner that is
198        more efficient than the old way of doing things because it avoids levels of
199        recursion in the regex matching; (c) add a paragraph to the documentation
200        for the FullMatch() function.
202     6. The escape sequence \n was being treated as whatever was defined as
203        "newline". Not only was this contrary to the documentation, which states
204        that \n is character 10 (hex 0A), but it also went horribly wrong when
205        "newline" was defined as CRLF. This has been fixed.
207     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
208        was being set to -1 for the "end of line" case (supposedly a value that no
209        character can have). Though this value is never used (the check for end of
210        line is "zero bytes in current character"), it caused compiler complaints.
211        I've changed it to 0xffffffff.
213     8. In pcre_version.c, the version string was being built by a sequence of
214        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
215        string (as it is for production releases) called a macro with an empty
216        argument. The C standard says the result of this is undefined. The gcc
217        compiler treats it as an empty string (which was what was wanted) but it is
218        reported that Visual C gives an error. The source has been hacked around to
219        avoid this problem.
221     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
222        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
223        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
224        of them did).
226    10. Originally, pcretest opened its input and output without "b"; then I was
227        told that "b" was needed in some environments, so it was added for release
228        5.0 to both the input and output. (It makes no difference on Unix-like
229        systems.) Later I was told that it is wrong for the input on Windows. I've
230        now abstracted the modes into two macros, to make it easier to fiddle with
231        them, and removed "b" from the input mode under Windows.
233    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
235    12. Added -help and --help to pcretest as an official way of being reminded
236        of the options.
238    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
239        and pcrecpp.cc because they annoy compilers at high warning levels.
241    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
243    15. Fixed an occurrence of == in configure.ac that should have been = (shell
244        scripts are not C programs :-) and which was not noticed because it works
245        on Linux.
247    16. pcretest is supposed to handle any length of pattern and data line (as one
248        line or as a continued sequence of lines) by extending its input buffer if
249        necessary. This feature was broken for very long pattern lines, leading to
250        a string of junk being passed to pcre_compile() if the pattern was longer
251        than about 50K.
253    17. I have done a major re-factoring of the way pcre_compile() computes the
254        amount of memory needed for a compiled pattern. Previously, there was code
255        that made a preliminary scan of the pattern in order to do this. That was
256        OK when PCRE was new, but as the facilities have expanded, it has become
257        harder and harder to keep it in step with the real compile phase, and there
258        have been a number of bugs (see for example, 4 above). I have now found a
259        cunning way of running the real compile function in a "fake" mode that
260        enables it to compute how much memory it would need, while actually only
261        ever using a few hundred bytes of working memory and without too many
262        tests of the mode. This should make future maintenance and development
263        easier. A side effect of this work is that the limit of 200 on the nesting
264        depth of parentheses has been removed (though this was never a serious
265        limitation, I suspect). However, there is a downside: pcre_compile() now
266        runs more slowly than before (30% or more, depending on the pattern). I
267        hope this isn't a big issue. There is no effect on runtime performance.
269    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
270        newline (only possible for the last line of a file) and it was a
271        pattern that set a locale (followed by /Lsomething), pcretest crashed.
273    19. Added additional timing features to pcretest. (1) The -tm option now times
274        matching only, not compiling. (2) Both -t and -tm can be followed, as a
275        separate command line item, by a number that specifies the number of
276        repeats to use when timing. The default is 50000; this gives better
277        precision, but takes uncomfortably long for very large patterns.
279    20. Extended pcre_study() to be more clever in cases where a branch of a
280        subpattern has no definite first character. For example, (a*|b*)[cd] would
281        previously give no result from pcre_study(). Now it recognizes that the
282        first character must be a, b, c, or d.
284    21. There was an incorrect error "recursive call could loop indefinitely" if
285        a subpattern (or the entire pattern) that was being tested for matching an
286        empty string contained only one non-empty item after a nested subpattern.
287        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
288        incorrectly, because the \d was being skipped in the check.
290    22. The pcretest program now has a new pattern option /B and a command line
291        option -b, which is equivalent to adding /B to every pattern. This causes
292        it to show the compiled bytecode, without the additional information that
293        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
294        is the same as /B/I).
296    23. A new optimization is now able automatically to treat some sequences such
297        as a*b as a*+b. More specifically, if something simple (such as a character
298        or a simple class like \d) has an unlimited quantifier, and is followed by
299        something that cannot possibly match the quantified thing, the quantifier
300        is automatically "possessified".
302    24. A recursive reference to a subpattern whose number was greater than 39
303        went wrong under certain circumstances in UTF-8 mode. This bug could also
304        have affected the operation of pcre_study().
306    25. Realized that a little bit of performance could be had by replacing
307        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
309    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
311    27. Possessive quantifiers such as a++ were previously implemented by turning
312        them into atomic groups such as ($>a+). Now they have their own opcodes,
313        which improves performance. This includes the automatically created ones
314        from 23 above.
316    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
317        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
318        the first matched character to be a colon. This applied both to named and
319        numbered groups.
321    29. The ucpinternal.h header file was missing its idempotency #ifdef.
323    30. I was sent a "project" file called libpcre.a.dev which I understand makes
324        building PCRE on Windows easier, so I have included it in the distribution.
326    31. There is now a check in pcretest against a ridiculously large number being
327        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
328        loop, the loop is abandoned.
330    32. Forward references to subpatterns in conditions such as (?(2)...) where
331        subpattern 2 is defined later cause pcre_compile() to search forwards in
332        the pattern for the relevant set of parentheses. This search went wrong
333        when there were unescaped parentheses in a character class, parentheses
334        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
336    33. "Subroutine" calls and backreferences were previously restricted to
337        referencing subpatterns earlier in the regex. This restriction has now
338        been removed.
340    34. Added a number of extra features that are going to be in Perl 5.10. On the
341        whole, these are just syntactic alternatives for features that PCRE had
342        previously implemented using the Python syntax or my own invention. The
343        other formats are all retained for compatibility.
345        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
346            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
347            also .NET compatible.
349        (b) A recursion or subroutine call to a named group can now be defined as
350            (?&name) as well as (?P>name).
352        (c) A backreference to a named group can now be defined as \k<name> or
353            \k'name' as well as (?P=name). The new forms, as well as being in Perl
354            5.10, are also .NET compatible.
356        (d) A conditional reference to a named group can now use the syntax
357            (?(<name>) or (?('name') as well as (?(name).
359        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
360            groups (named and numbered) that are never evaluated inline, but can be
361            called as "subroutines" from elsewhere. In effect, the DEFINE condition
362            is always false. There may be only one alternative in such a group.
364        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
365            as the simple (?(R). The condition is true only if the most recent
366            recursion is that of the given number or name. It does not search out
367            through the entire recursion stack.
369        (g) The escape \gN or \g{N} has been added, where N is a positive or
370            negative number, specifying an absolute or relative reference.
372    35. Tidied to get rid of some further signed/unsigned compiler warnings and
373        some "unreachable code" warnings.
375    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
376        things, this adds five new scripts.
378    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
379        There were also incompatibilities regarding the handling of \Q..\E inside
380        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
381        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
383    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
384        matches an empty string, and forcibly breaks the loop. There were bugs in
385        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
386        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
387        separate and independent bugs (that affected different cases) have been
388        fixed.
390    39. Refactored the code to abolish the use of different opcodes for small
391        capturing bracket numbers. This is a tidy that I avoided doing when I
392        removed the limit on the number of capturing brackets for 3.5 back in 2001.
393        The new approach is not only tidier, it makes it possible to reduce the
394        memory needed to fix the previous bug (38).
396    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
397        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
398        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
399        mode.
401    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
402        report.
404    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
405        copy construction and assignment in the C++ wrapper.
407    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
408        couple of bugs that could have given wrong results in the "--newline=crlf"
409        case.
411    44. Added a number of casts and did some reorganization of signed/unsigned int
412        variables following suggestions from Dair Grant. Also renamed the variable
413        "this" as "item" because it is a C++ keyword.
415    45. Arranged for dftables to add
417          #include "pcre_internal.h"
419        to pcre_chartables.c because without it, gcc 4.x may remove the array
420        definition from the final binary if PCRE is built into a static library and
421        dead code stripping is activated.
423    46. For an unanchored pattern, if a match attempt fails at the start of a
424        newline sequence, and the newline setting is CRLF or ANY, and the next two
425        characters are CRLF, advance by two characters instead of one.
428    Version 6.7 04-Jul-06
429    ---------------------
431     1. In order to handle tests when input lines are enormously long, pcretest has
432        been re-factored so that it automatically extends its buffers when
433        necessary. The code is crude, but this _is_ just a test program. The
434        default size has been increased from 32K to 50K.
436     2. The code in pcre_study() was using the value of the re argument before
437        testing it for NULL. (Of course, in any sensible call of the function, it
438        won't be NULL.)
440     3. The memmove() emulation function in pcre_internal.h, which is used on
441        systems that lack both memmove() and bcopy() - that is, hardly ever -
442        was missing a "static" storage class specifier.
444     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
445        containing an extended class (one that cannot be represented by a bitmap
446        because it contains high-valued characters or Unicode property items, e.g.
447        [\pZ]). Almost always one would set UTF-8 mode when processing such a
448        pattern, but PCRE should not loop if you do not (it no longer does).
449        [Detail: two cases were found: (a) a repeated subpattern containing an
450        extended class; (b) a recursive reference to a subpattern that followed a
451        previous extended class. It wasn't skipping over the extended class
452        correctly when UTF-8 mode was not set.]
454     5. A negated single-character class was not being recognized as fixed-length
455        in lookbehind assertions such as (?<=[^f]), leading to an incorrect
456        compile error "lookbehind assertion is not fixed length".
458     6. The RunPerlTest auxiliary script was showing an unexpected difference
459        between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
460        write a Perl script that can interpret lines of an input file either as
461        byte characters or as UTF-8, which is what "perltest" was being required to
462        do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
463        can't do is switch easily at run time between having the "use utf8;" pragma
464        or not. In the end, I fudged it by using the RunPerlTest script to insert
465        "use utf8;" explicitly for the UTF-8 tests.
467     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
468        the end of the subject string, contrary to the documentation and to what
469        Perl does. This was true of both matching functions. Now it matches only at
470        the start of the subject and immediately after *internal* newlines.
472     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
473        a pointer to an int instead of a pointer to an unsigned long int. This
474        caused problems on 64-bit systems.
476     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
477        instance of the 'standard' template library not being so standard".
479    10. There was no check on the number of named subpatterns nor the maximum
480        length of a subpattern name. The product of these values is used to compute
481        the size of the memory block for a compiled pattern. By supplying a very
482        long subpattern name and a large number of named subpatterns, the size
483        computation could be caused to overflow. This is now prevented by limiting
484        the length of names to 32 characters, and the number of named subpatterns
485        to 10,000.
487    11. Subpatterns that are repeated with specific counts have to be replicated in
488        the compiled pattern. The size of memory for this was computed from the
489        length of the subpattern and the repeat count. The latter is limited to
490        65535, but there was no limit on the former, meaning that integer overflow
491        could in principle occur. The compiled length of a repeated subpattern is
492        now limited to 30,000 bytes in order to prevent this.
494    12. Added the optional facility to have named substrings with the same name.
496    13. Added the ability to use a named substring as a condition, using the
497        Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
498        are numbers (not recommended). Forward references are permitted.
500    14. Added forward references in named backreferences (if you see what I mean).
502    15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
503        pattern could run off the end of the subject. For example, the pattern
504        "(?s)(.{1,5})"8 did this with the subject "ab".
506    16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
507        PCRE_CASELESS was set when matching characters that were quantified with ?
508        or *.
510    17. A character class other than a single negated character that had a minimum
511        but no maximum quantifier - for example [ab]{6,} - was not handled
512        correctly by pce_dfa_exec(). It would match only one character.
514    18. A valid (though odd) pattern that looked like a POSIX character
515        class but used an invalid character after [ (for example [[,abc,]]) caused
516        pcre_compile() to give the error "Failed: internal error: code overflow" or
517        in some cases to crash with a glibc free() error. This could even happen if
518        the pattern terminated after [[ but there just happened to be a sequence of
519        letters, a binary zero, and a closing ] in the memory that followed.
521    19. Perl's treatment of octal escapes in the range \400 to \777 has changed
522        over the years. Originally (before any Unicode support), just the bottom 8
523        bits were taken. Thus, for example, \500 really meant \100. Nowadays the
524        output from "man perlunicode" includes this:
526          The regular expression compiler produces polymorphic opcodes.  That
527          is, the pattern adapts to the data and automatically switches to
528          the Unicode character scheme when presented with Unicode data--or
529          instead uses a traditional byte scheme when presented with byte
530          data.
532        Sadly, a wide octal escape does not cause a switch, and in a string with
533        no other multibyte characters, these octal escapes are treated as before.
534        Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
535        /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
536        Unicode string.
538        I have not perpetrated such confusion in PCRE. Up till now, it took just
539        the bottom 8 bits, as in old Perl. I have now made octal escapes with
540        values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
541        translate to the appropriate multibyte character.
543    29. Applied some refactoring to reduce the number of warnings from Microsoft
544        and Borland compilers. This has included removing the fudge introduced
545        seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
546        a warning about an unused variable.
548    21. PCRE has not included VT (character 0x0b) in the set of whitespace
549        characters since release 4.0, because Perl (from release 5.004) does not.
550        [Or at least, is documented not to: some releases seem to be in conflict
551        with the documentation.] However, when a pattern was studied with
552        pcre_study() and all its branches started with \s, PCRE still included VT
553        as a possible starting character. Of course, this did no harm; it just
554        caused an unnecessary match attempt.
556    22. Removed a now-redundant internal flag bit that recorded the fact that case
557        dependency changed within the pattern. This was once needed for "required
558        byte" processing, but is no longer used. This recovers a now-scarce options
559        bit. Also moved the least significant internal flag bit to the most-
560        significant bit of the word, which was not previously used (hangover from
561        the days when it was an int rather than a uint) to free up another bit for
562        the future.
564    23. Added support for CRLF line endings as well as CR and LF. As well as the
565        default being selectable at build time, it can now be changed at runtime
566        via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
567        specify that it is scanning data with non-default line endings.
569    24. Changed the definition of CXXLINK to make it agree with the definition of
570        LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
572    25. Applied Ian Taylor's patches to avoid using another stack frame for tail
573        recursions. This makes a big different to stack usage for some patterns.
575    26. If a subpattern containing a named recursion or subroutine reference such
576        as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
577        the space required for the compiled pattern went wrong and gave too small a
578        value. Depending on the environment, this could lead to "Failed: internal
579        error: code overflow at offset 49" or "glibc detected double free or
580        corruption" errors.
582    27. Applied patches from Google (a) to support the new newline modes and (b) to
583        advance over multibyte UTF-8 characters in GlobalReplace.
585    28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
586        difference for some implementation of PCRE in some Windows version.
588    29. Added some extra testing facilities to pcretest:
590        \q<number>   in a data line sets the "match limit" value
591        \Q<number>   in a data line sets the "match recursion limt" value
592        -S <number>  sets the stack size, where <number> is in megabytes
594        The -S option isn't available for Windows.
597    Version 6.6 06-Feb-06
598    ---------------------
600     1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
601        in pcreposix.h. I have copied the definition from pcre.h.
603     2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
604        because pcre.h is no longer a built file.
606     3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
607        not normally included in the compiled code.
610    Version 6.5 01-Feb-06
611    ---------------------
613     1. When using the partial match feature with pcre_dfa_exec(), it was not
614        anchoring the second and subsequent partial matches at the new starting
615        point. This could lead to incorrect results. For example, with the pattern
616        /1234/, partially matching against "123" and then "a4" gave a match.
618     2. Changes to pcregrep:
620        (a) All non-match returns from pcre_exec() were being treated as failures
621            to match the line. Now, unless the error is PCRE_ERROR_NOMATCH, an
622            error message is output. Some extra information is given for the
623            PCRE_ERROR_MATCHLIMIT and PCRE_ERROR_RECURSIONLIMIT errors, which are
624            probably the only errors that are likely to be caused by users (by
625            specifying a regex that has nested indefinite repeats, for instance).
626            If there are more than 20 of these errors, pcregrep is abandoned.
628        (b) A binary zero was treated as data while matching, but terminated the
629            output line if it was written out. This has been fixed: binary zeroes
630            are now no different to any other data bytes.
632        (c) Whichever of the LC_ALL or LC_CTYPE environment variables is set is
633            used to set a locale for matching. The --locale=xxxx long option has
634            been added (no short equivalent) to specify a locale explicitly on the
635            pcregrep command, overriding the environment variables.
637        (d) When -B was used with -n, some line numbers in the output were one less
638            than they should have been.
640        (e) Added the -o (--only-matching) option.
642        (f) If -A or -C was used with -c (count only), some lines of context were
643            accidentally printed for the final match.
645        (g) Added the -H (--with-filename) option.
647        (h) The combination of options -rh failed to suppress file names for files
648            that were found from directory arguments.
650        (i) Added the -D (--devices) and -d (--directories) options.
652        (j) Added the -F (--fixed-strings) option.
654        (k) Allow "-" to be used as a file name for -f as well as for a data file.
656        (l) Added the --colo(u)r option.
658        (m) Added Jeffrey Friedl's -S testing option, but within #ifdefs so that it
659            is not present by default.
661     3. A nasty bug was discovered in the handling of recursive patterns, that is,
662        items such as (?R) or (?1), when the recursion could match a number of
663        alternatives. If it matched one of the alternatives, but subsequently,
664        outside the recursion, there was a failure, the code tried to back up into
665        the recursion. However, because of the way PCRE is implemented, this is not
666        possible, and the result was an incorrect result from the match.
668        In order to prevent this happening, the specification of recursion has
669        been changed so that all such subpatterns are automatically treated as
670        atomic groups. Thus, for example, (?R) is treated as if it were (?>(?R)).
672     4. I had overlooked the fact that, in some locales, there are characters for
673        which isalpha() is true but neither isupper() nor islower() are true. In
674        the fr_FR locale, for instance, the \xAA and \xBA characters (ordmasculine
675        and ordfeminine) are like this. This affected the treatment of \w and \W
676        when they appeared in character classes, but not when they appeared outside
677        a character class. The bit map for "word" characters is now created
678        separately from the results of isalnum() instead of just taking it from the
679        upper, lower, and digit maps. (Plus the underscore character, of course.)
681     5. The above bug also affected the handling of POSIX character classes such as
682        [[:alpha:]] and [[:alnum:]]. These do not have their own bit maps in PCRE's
683        permanent tables. Instead, the bit maps for such a class were previously
684        created as the appropriate unions of the upper, lower, and digit bitmaps.
685        Now they are created by subtraction from the [[:word:]] class, which has
686        its own bitmap.
688     6. The [[:blank:]] character class matches horizontal, but not vertical space.
689        It is created by subtracting the vertical space characters (\x09, \x0a,
690        \x0b, \x0c) from the [[:space:]] bitmap. Previously, however, the
691        subtraction was done in the overall bitmap for a character class, meaning
692        that a class such as [\x0c[:blank:]] was incorrect because \x0c would not
693        be recognized. This bug has been fixed.
695     7. Patches from the folks at Google:
697          (a) pcrecpp.cc: "to handle a corner case that may or may not happen in
698          real life, but is still worth protecting against".
700          (b) pcrecpp.cc: "corrects a bug when negative radixes are used with
701          regular expressions".
703          (c) pcre_scanner.cc: avoid use of std::count() because not all systems
704          have it.
706          (d) Split off pcrecpparg.h from pcrecpp.h and had the former built by
707          "configure" and the latter not, in order to fix a problem somebody had
708          with compiling the Arg class on HP-UX.
710          (e) Improve the error-handling of the C++ wrapper a little bit.
712          (f) New tests for checking recursion limiting.
714     8. The pcre_memmove() function, which is used only if the environment does not
715        have a standard memmove() function (and is therefore rarely compiled),
716        contained two bugs: (a) use of int instead of size_t, and (b) it was not
717        returning a result (though PCRE never actually uses the result).
719     9. In the POSIX regexec() interface, if nmatch is specified as a ridiculously
720        large number - greater than INT_MAX/(3*sizeof(int)) - REG_ESPACE is
721        returned instead of calling malloc() with an overflowing number that would
722        most likely cause subsequent chaos.
724    10. The debugging option of pcretest was not showing the NO_AUTO_CAPTURE flag.
726    11. The POSIX flag REG_NOSUB is now supported. When a pattern that was compiled
727        with this option is matched, the nmatch and pmatch options of regexec() are
728        ignored.
730    12. Added REG_UTF8 to the POSIX interface. This is not defined by POSIX, but is
731        provided in case anyone wants to the the POSIX interface with UTF-8
732        strings.
734    13. Added CXXLDFLAGS to the Makefile parameters to provide settings only on the
735        C++ linking (needed for some HP-UX environments).
737    14. Avoid compiler warnings in get_ucpname() when compiled without UCP support
738        (unused parameter) and in the pcre_printint() function (omitted "default"
739        switch label when the default is to do nothing).
741    15. Added some code to make it possible, when PCRE is compiled as a C++
742        library, to replace subject pointers for pcre_exec() with a smart pointer
743        class, thus making it possible to process discontinuous strings.
745    16. The two macros PCRE_EXPORT and PCRE_DATA_SCOPE are confusing, and perform
746        much the same function. They were added by different people who were trying
747        to make PCRE easy to compile on non-Unix systems. It has been suggested
748        that PCRE_EXPORT be abolished now that there is more automatic apparatus
749        for compiling on Windows systems. I have therefore replaced it with
750        PCRE_DATA_SCOPE. This is set automatically for Windows; if not set it
751        defaults to "extern" for C or "extern C" for C++, which works fine on
752        Unix-like systems. It is now possible to override the value of PCRE_DATA_
753        SCOPE with something explicit in config.h. In addition:
755        (a) pcreposix.h still had just "extern" instead of either of these macros;
756            I have replaced it with PCRE_DATA_SCOPE.
758        (b) Functions such as _pcre_xclass(), which are internal to the library,
759            but external in the C sense, all had PCRE_EXPORT in their definitions.
760            This is apparently wrong for the Windows case, so I have removed it.
761            (It makes no difference on Unix-like systems.)
763    17. Added a new limit, MATCH_LIMIT_RECURSION, which limits the depth of nesting
764        of recursive calls to match(). This is different to MATCH_LIMIT because
765        that limits the total number of calls to match(), not all of which increase
766        the depth of recursion. Limiting the recursion depth limits the amount of
767        stack (or heap if NO_RECURSE is set) that is used. The default can be set
768        when PCRE is compiled, and changed at run time. A patch from Google adds
769        this functionality to the C++ interface.
771    18. Changes to the handling of Unicode character properties:
773        (a) Updated the table to Unicode 4.1.0.
775        (b) Recognize characters that are not in the table as "Cn" (undefined).
777        (c) I revised the way the table is implemented to a much improved format
778            which includes recognition of ranges. It now supports the ranges that
779            are defined in UnicodeData.txt, and it also amalgamates other
780            characters into ranges. This has reduced the number of entries in the
781            table from around 16,000 to around 3,000, thus reducing its size
782            considerably. I realized I did not need to use a tree structure after
783            all - a binary chop search is just as efficient. Having reduced the
784            number of entries, I extended their size from 6 bytes to 8 bytes to
785            allow for more data.
787        (d) Added support for Unicode script names via properties such as \p{Han}.
789    19. In UTF-8 mode, a backslash followed by a non-Ascii character was not
790        matching that character.
792    20. When matching a repeated Unicode property with a minimum greater than zero,
793        (for example \pL{2,}), PCRE could look past the end of the subject if it
794        reached it while seeking the minimum number of characters. This could
795        happen only if some of the characters were more than one byte long, because
796        there is a check for at least the minimum number of bytes.
798    21. Refactored the implementation of \p and \P so as to be more general, to
799        allow for more different types of property in future. This has changed the
800        compiled form incompatibly. Anybody with saved compiled patterns that use
801        \p or \P will have to recompile them.
803    22. Added "Any" and "L&" to the supported property types.
805    23. Recognize \x{...} as a code point specifier, even when not in UTF-8 mode,
806        but give a compile time error if the value is greater than 0xff.
808    24. The man pages for pcrepartial, pcreprecompile, and pcre_compile2 were
809        accidentally not being installed or uninstalled.
811    25. The pcre.h file was built from pcre.h.in, but the only changes that were
812        made were to insert the current release number. This seemed silly, because
813        it made things harder for people building PCRE on systems that don't run
814        "configure". I have turned pcre.h into a distributed file, no longer built
815        by "configure", with the version identification directly included. There is
816        no longer a pcre.h.in file.
818        However, this change necessitated a change to the pcre-config script as
819        well. It is built from pcre-config.in, and one of the substitutions was the
820        release number. I have updated configure.ac so that ./configure now finds
821        the release number by grepping pcre.h.
823    26. Added the ability to run the tests under valgrind.
826    Version 6.4 05-Sep-05
827    ---------------------
829     1. Change 6.0/10/(l) to pcregrep introduced a bug that caused separator lines
830        "--" to be printed when multiple files were scanned, even when none of the
831        -A, -B, or -C options were used. This is not compatible with Gnu grep, so I
832        consider it to be a bug, and have restored the previous behaviour.
834     2. A couple of code tidies to get rid of compiler warnings.
836     3. The pcretest program used to cheat by referring to symbols in the library
837        whose names begin with _pcre_. These are internal symbols that are not
838        really supposed to be visible externally, and in some environments it is
839        possible to suppress them. The cheating is now confined to including
840        certain files from the library's source, which is a bit cleaner.
842     4. Renamed pcre.in as pcre.h.in to go with pcrecpp.h.in; it also makes the
843        file's purpose clearer.
845     5. Reorganized pcre_ucp_findchar().
848    Version 6.3 15-Aug-05
849    ---------------------
851     1. The file libpcre.pc.in did not have general read permission in the tarball.
853     2. There were some problems when building without C++ support:
855        (a) If C++ support was not built, "make install" and "make test" still
856            tried to test it.
858        (b) There were problems when the value of CXX was explicitly set. Some
859            changes have been made to try to fix these, and ...
861        (c) --disable-cpp can now be used to explicitly disable C++ support.
863        (d) The use of @CPP_OBJ@ directly caused a blank line preceded by a
864            backslash in a target when C++ was disabled. This confuses some
865            versions of "make", apparently. Using an intermediate variable solves
866            this. (Same for CPP_LOBJ.)
868     3. $(LINK_FOR_BUILD) now includes $(CFLAGS_FOR_BUILD) and $(LINK)
869        (non-Windows) now includes $(CFLAGS) because these flags are sometimes
870        necessary on certain architectures.
872     4. Added a setting of -export-symbols-regex to the link command to remove
873        those symbols that are exported in the C sense, but actually are local
874        within the library, and not documented. Their names all begin with
875        "_pcre_". This is not a perfect job, because (a) we have to except some
876        symbols that pcretest ("illegally") uses, and (b) the facility isn't always
877        available (and never for static libraries). I have made a note to try to
878        find a way round (a) in the future.
881    Version 6.2 01-Aug-05
882    ---------------------
884     1. There was no test for integer overflow of quantifier values. A construction
885        such as {1111111111111111} would give undefined results. What is worse, if
886        a minimum quantifier for a parenthesized subpattern overflowed and became
887        negative, the calculation of the memory size went wrong. This could have
888        led to memory overwriting.
890     2. Building PCRE using VPATH was broken. Hopefully it is now fixed.
892     3. Added "b" to the 2nd argument of fopen() in dftables.c, for non-Unix-like
893        operating environments where this matters.
895     4. Applied Giuseppe Maxia's patch to add additional features for controlling
896        PCRE options from within the C++ wrapper.
898     5. Named capturing subpatterns were not being correctly counted when a pattern
899        was compiled. This caused two problems: (a) If there were more than 100
900        such subpatterns, the calculation of the memory needed for the whole
901        compiled pattern went wrong, leading to an overflow error. (b) Numerical
902        back references of the form \12, where the number was greater than 9, were
903        not recognized as back references, even though there were sufficient
904        previous subpatterns.
906     6. Two minor patches to pcrecpp.cc in order to allow it to compile on older
907        versions of gcc, e.g. 2.95.4.
910    Version 6.1 21-Jun-05
911    ---------------------
913     1. There was one reference to the variable "posix" in pcretest.c that was not
914        surrounded by "#if !defined NOPOSIX".
916     2. Make it possible to compile pcretest without DFA support, UTF8 support, or
917        the cross-check on the old pcre_info() function, for the benefit of the
918        cut-down version of PCRE that is currently imported into Exim.
920     3. A (silly) pattern starting with (?i)(?-i) caused an internal space
921        allocation error. I've done the easy fix, which wastes 2 bytes for sensible
922        patterns that start (?i) but I don't think that matters. The use of (?i) is
923        just an example; this all applies to the other options as well.
925     4. Since libtool seems to echo the compile commands it is issuing, the output
926        from "make" can be reduced a bit by putting "@" in front of each libtool
927        compile command.
929     5. Patch from the folks at Google for configure.in to be a bit more thorough
930        in checking for a suitable C++ installation before trying to compile the
931        C++ stuff. This should fix a reported problem when a compiler was present,
932        but no suitable headers.
934     6. The man pages all had just "PCRE" as their title. I have changed them to
935        be the relevant file name. I have also arranged that these names are
936        retained in the file doc/pcre.txt, which is a concatenation in text format
937        of all the man pages except the little individual ones for each function.
939     7. The NON-UNIX-USE file had not been updated for the different set of source
940        files that come with release 6. I also added a few comments about the C++
941        wrapper.
944    Version 6.0 07-Jun-05
945    ---------------------
947     1. Some minor internal re-organization to help with my DFA experiments.
949     2. Some missing #ifdef SUPPORT_UCP conditionals in pcretest and printint that
950        didn't matter for the library itself when fully configured, but did matter
951        when compiling without UCP support, or within Exim, where the ucp files are
952        not imported.
954     3. Refactoring of the library code to split up the various functions into
955        different source modules. The addition of the new DFA matching code (see
956        below) to a single monolithic source would have made it really too
957        unwieldy, quite apart from causing all the code to be include in a
958        statically linked application, when only some functions are used. This is
959        relevant even without the DFA addition now that patterns can be compiled in
960        one application and matched in another.
962        The downside of splitting up is that there have to be some external
963        functions and data tables that are used internally in different modules of
964        the library but which are not part of the API. These have all had their
965        names changed to start with "_pcre_" so that they are unlikely to clash
966        with other external names.
968     4. Added an alternate matching function, pcre_dfa_exec(), which matches using
969        a different (DFA) algorithm. Although it is slower than the original
970        function, it does have some advantages for certain types of matching
971        problem.
973     5. Upgrades to pcretest in order to test the features of pcre_dfa_exec(),
974        including restarting after a partial match.
976     6. A patch for pcregrep that defines INVALID_FILE_ATTRIBUTES if it is not
977        defined when compiling for Windows was sent to me. I have put it into the
978        code, though I have no means of testing or verifying it.
980     7. Added the pcre_refcount() auxiliary function.
982     8. Added the PCRE_FIRSTLINE option. This constrains an unanchored pattern to
983        match before or at the first newline in the subject string. In pcretest,
984        the /f option on a pattern can be used to set this.
986     9. A repeated \w when used in UTF-8 mode with characters greater than 256
987        would behave wrongly. This has been present in PCRE since release 4.0.
989    10. A number of changes to the pcregrep command:
991        (a) Refactored how -x works; insert ^(...)$ instead of setting
992            PCRE_ANCHORED and checking the length, in preparation for adding
993            something similar for -w.
995        (b) Added the -w (match as a word) option.
997        (c) Refactored the way lines are read and buffered so as to have more
998            than one at a time available.
1000        (d) Implemented a pcregrep test script.
1002        (e) Added the -M (multiline match) option. This allows patterns to match
1003            over several lines of the subject. The buffering ensures that at least
1004            8K, or the rest of the document (whichever is the shorter) is available
1005            for matching (and similarly the previous 8K for lookbehind assertions).
1007        (f) Changed the --help output so that it now says
1009              -w, --word-regex(p)
1011            instead of two lines, one with "regex" and the other with "regexp"
1012            because that confused at least one person since the short forms are the
1013            same. (This required a bit of code, as the output is generated
1014            automatically from a table. It wasn't just a text change.)
1016        (g) -- can be used to terminate pcregrep options if the next thing isn't an
1017            option but starts with a hyphen. Could be a pattern or a path name
1018            starting with a hyphen, for instance.
1020        (h) "-" can be given as a file name to represent stdin.
1022        (i) When file names are being printed, "(standard input)" is used for
1023            the standard input, for compatibility with GNU grep. Previously
1024            "<stdin>" was used.
1026        (j) The option --label=xxx can be used to supply a name to be used for
1027            stdin when file names are being printed. There is no short form.
1029        (k) Re-factored the options decoding logic because we are going to add
1030            two more options that take data. Such options can now be given in four
1031            different ways, e.g. "-fname", "-f name", "--file=name", "--file name".
1033        (l) Added the -A, -B, and -C options for requesting that lines of context
1034            around matches be printed.
1036        (m) Added the -L option to print the names of files that do not contain
1037            any matching lines, that is, the complement of -l.
1039        (n) The return code is 2 if any file cannot be opened, but pcregrep does
1040            continue to scan other files.
1042        (o) The -s option was incorrectly implemented. For compatibility with other
1043            greps, it now suppresses the error message for a non-existent or non-
1044            accessible file (but not the return code). There is a new option called
1045            -q that suppresses the output of matching lines, which was what -s was
1046            previously doing.
1048        (p) Added --include and --exclude options to specify files for inclusion
1049            and exclusion when recursing.
1051    11. The Makefile was not using the Autoconf-supported LDFLAGS macro properly.
1052        Hopefully, it now does.
1054    12. Missing cast in pcre_study().
1056    13. Added an "uninstall" target to the makefile.
1058    14. Replaced "extern" in the function prototypes in Makefile.in with
1059        "PCRE_DATA_SCOPE", which defaults to 'extern' or 'extern "C"' in the Unix
1060        world, but is set differently for Windows.
1062    15. Added a second compiling function called pcre_compile2(). The only
1063        difference is that it has an extra argument, which is a pointer to an
1064        integer error code. When there is a compile-time failure, this is set
1065        non-zero, in addition to the error test pointer being set to point to an
1066        error message. The new argument may be NULL if no error number is required
1067        (but then you may as well call pcre_compile(), which is now just a
1068        wrapper). This facility is provided because some applications need a
1069        numeric error indication, but it has also enabled me to tidy up the way
1070        compile-time errors are handled in the POSIX wrapper.
1072    16. Added VPATH=.libs to the makefile; this should help when building with one
1073        prefix path and installing with another. (Or so I'm told by someone who
1074        knows more about this stuff than I do.)
1076    17. Added a new option, REG_DOTALL, to the POSIX function regcomp(). This
1077        passes PCRE_DOTALL to the pcre_compile() function, making the "." character
1078        match everything, including newlines. This is not POSIX-compatible, but
1079        somebody wanted the feature. From pcretest it can be activated by using
1080        both the P and the s flags.
1082    18. AC_PROG_LIBTOOL appeared twice in Makefile.in. Removed one.
1084    19. libpcre.pc was being incorrectly installed as executable.
1086    20. A couple of places in pcretest check for end-of-line by looking for '\n';
1087        it now also looks for '\r' so that it will work unmodified on Windows.
1089    21. Added Google's contributed C++ wrapper to the distribution.
1091    22. Added some untidy missing memory free() calls in pcretest, to keep
1092        Electric Fence happy when testing.
1096    Version 5.0 13-Sep-04
1097    ---------------------
1099     1. Internal change: literal characters are no longer packed up into items
1100        containing multiple characters in a single byte-string. Each character
1101        is now matched using a separate opcode. However, there may be more than one
1102        byte in the character in UTF-8 mode.
1104     2. The pcre_callout_block structure has two new fields: pattern_position and
1105        next_item_length. These contain the offset in the pattern to the next match
1106        item, and its length, respectively.
1108     3. The PCRE_AUTO_CALLOUT option for pcre_compile() requests the automatic
1109        insertion of callouts before each pattern item. Added the /C option to
1110        pcretest to make use of this.
1112     4. On the advice of a Windows user, the lines
1114          #if defined(_WIN32) || defined(WIN32)
1115          _setmode( _fileno( stdout ), 0x8000 );
1116          #endif  /* defined(_WIN32) || defined(WIN32) */
1118        have been added to the source of pcretest. This apparently does useful
1119        magic in relation to line terminators.
1121     5. Changed "r" and "w" in the calls to fopen() in pcretest to "rb" and "wb"
1122        for the benefit of those environments where the "b" makes a difference.
1124     6. The icc compiler has the same options as gcc, but "configure" doesn't seem
1125        to know about it. I have put a hack into configure.in that adds in code
1126        to set GCC=yes if CC=icc. This seems to end up at a point in the
1127        generated configure script that is early enough to affect the setting of
1128        compiler options, which is what is needed, but I have no means of testing
1129        whether it really works. (The user who reported this had patched the
1130        generated configure script, which of course I cannot do.)
1132        LATER: After change 22 below (new libtool files), the configure script
1133        seems to know about icc (and also ecc). Therefore, I have commented out
1134        this hack in configure.in.
1136     7. Added support for pkg-config (2 patches were sent in).
1138     8. Negated POSIX character classes that used a combination of internal tables
1139        were completely broken. These were [[:^alpha:]], [[:^alnum:]], and
1140        [[:^ascii]]. Typically, they would match almost any characters. The other
1141        POSIX classes were not broken in this way.
1143     9. Matching the pattern "\b.*?" against "ab cd", starting at offset 1, failed
1144        to find the match, as PCRE was deluded into thinking that the match had to
1145        start at the start point or following a newline. The same bug applied to
1146        patterns with negative forward assertions or any backward assertions
1147        preceding ".*" at the start, unless the pattern required a fixed first
1148        character. This was a failing pattern: "(?!.bcd).*". The bug is now fixed.
1150    10. In UTF-8 mode, when moving forwards in the subject after a failed match
1151        starting at the last subject character, bytes beyond the end of the subject
1152        string were read.
1154    11. Renamed the variable "class" as "classbits" to make life easier for C++
1155        users. (Previously there was a macro definition, but it apparently wasn't
1156        enough.)
1158    12. Added the new field "tables" to the extra data so that tables can be passed
1159        in at exec time, or the internal tables can be re-selected. This allows
1160        a compiled regex to be saved and re-used at a later time by a different
1161        program that might have everything at different addresses.
1163    13. Modified the pcre-config script so that, when run on Solaris, it shows a
1164        -R library as well as a -L library.
1166    14. The debugging options of pcretest (-d on the command line or D on a
1167        pattern) showed incorrect output for anything following an extended class
1168        that contained multibyte characters and which was followed by a quantifier.
1170    15. Added optional support for general category Unicode character properties
1171        via the \p, \P, and \X escapes. Unicode property support implies UTF-8
1172        support. It adds about 90K to the size of the library. The meanings of the
1173        inbuilt class escapes such as \d and \s have NOT been changed.
1175    16. Updated pcredemo.c to include calls to free() to release the memory for the
1176        compiled pattern.
1178    17. The generated file chartables.c was being created in the source directory
1179        instead of in the building directory. This caused the build to fail if the
1180        source directory was different from the building directory, and was
1181        read-only.
1183    18. Added some sample Win commands from Mark Tetrode into the NON-UNIX-USE
1184        file. No doubt somebody will tell me if they don't make sense... Also added
1185        Dan Mooney's comments about building on OpenVMS.
1187    19. Added support for partial matching via the PCRE_PARTIAL option for
1188        pcre_exec() and the \P data escape in pcretest.
1190    20. Extended pcretest with 3 new pattern features:
1192        (i)   A pattern option of the form ">rest-of-line" causes pcretest to
1193              write the compiled pattern to the file whose name is "rest-of-line".
1194              This is a straight binary dump of the data, with the saved pointer to
1195              the character tables forced to be NULL. The study data, if any, is
1196              written too. After writing, pcretest reads a new pattern.
1198        (ii)  If, instead of a pattern, "<rest-of-line" is given, pcretest reads a
1199              compiled pattern from the given file. There must not be any
1200              occurrences of "<" in the file name (pretty unlikely); if there are,
1201              pcretest will instead treat the initial "<" as a pattern delimiter.
1202              After reading in the pattern, pcretest goes on to read data lines as
1203              usual.
1205        (iii) The F pattern option causes pcretest to flip the bytes in the 32-bit
1206              and 16-bit fields in a compiled pattern, to simulate a pattern that
1207              was compiled on a host of opposite endianness.
1209    21. The pcre-exec() function can now cope with patterns that were compiled on
1210        hosts of opposite endianness, with this restriction:
1212          As for any compiled expression that is saved and used later, the tables
1213          pointer field cannot be preserved; the extra_data field in the arguments
1214          to pcre_exec() should be used to pass in a tables address if a value
1215          other than the default internal tables were used at compile time.
1217    22. Calling pcre_exec() with a negative value of the "ovecsize" parameter is
1218        now diagnosed as an error. Previously, most of the time, a negative number
1219        would have been treated as zero, but if in addition "ovector" was passed as
1220        NULL, a crash could occur.
1222    23. Updated the files ltmain.sh, config.sub, config.guess, and aclocal.m4 with
1223        new versions from the libtool 1.5 distribution (the last one is a copy of
1224        a file called libtool.m4). This seems to have fixed the need to patch
1225        "configure" to support Darwin 1.3 (which I used to do). However, I still
1226        had to patch ltmain.sh to ensure that ${SED} is set (it isn't on my
1227        workstation).
1229    24. Changed the PCRE licence to be the more standard "BSD" licence.
1232    Version 4.5 01-Dec-03
1233    ---------------------
1235     1. There has been some re-arrangement of the code for the match() function so
1236        that it can be compiled in a version that does not call itself recursively.
1237        Instead, it keeps those local variables that need separate instances for
1238        each "recursion" in a frame on the heap, and gets/frees frames whenever it
1239        needs to "recurse". Keeping track of where control must go is done by means
1240        of setjmp/longjmp. The whole thing is implemented by a set of macros that
1241        hide most of the details from the main code, and operates only if
1242        NO_RECURSE is defined while compiling pcre.c. If PCRE is built using the
1243        "configure" mechanism, "--disable-stack-for-recursion" turns on this way of
1244        operating.
1246        To make it easier for callers to provide specially tailored get/free
1247        functions for this usage, two new functions, pcre_stack_malloc, and
1248        pcre_stack_free, are used. They are always called in strict stacking order,
1249        and the size of block requested is always the same.
1251        The PCRE_CONFIG_STACKRECURSE info parameter can be used to find out whether
1252        PCRE has been compiled to use the stack or the heap for recursion. The
1253        -C option of pcretest uses this to show which version is compiled.
1255        A new data escape \S, is added to pcretest; it causes the amounts of store
1256        obtained and freed by both kinds of malloc/free at match time to be added
1257        to the output.
1259     2. Changed the locale test to use "fr_FR" instead of "fr" because that's
1260        what's available on my current Linux desktop machine.
1262     3. When matching a UTF-8 string, the test for a valid string at the start has
1263        been extended. If start_offset is not zero, PCRE now checks that it points
1264        to a byte that is the start of a UTF-8 character. If not, it returns
1265        PCRE_ERROR_BADUTF8_OFFSET (-11). Note: the whole string is still checked;
1266        this is necessary because there may be backward assertions in the pattern.
1267        When matching the same subject several times, it may save resources to use
1268        PCRE_NO_UTF8_CHECK on all but the first call if the string is long.
1270     4. The code for checking the validity of UTF-8 strings has been tightened so
1271        that it rejects (a) strings containing 0xfe or 0xff bytes and (b) strings
1272        containing "overlong sequences".
1274     5. Fixed a bug (appearing twice) that I could not find any way of exploiting!
1275        I had written "if ((digitab[*p++] && chtab_digit) == 0)" where the "&&"
1276        should have been "&", but it just so happened that all the cases this let
1277        through by mistake were picked up later in the function.
1279     6. I had used a variable called "isblank" - this is a C99 function, causing
1280        some compilers to warn. To avoid this, I renamed it (as "blankclass").
1282     7. Cosmetic: (a) only output another newline at the end of pcretest if it is
1283        prompting; (b) run "./pcretest /dev/null" at the start of the test script
1284        so the version is shown; (c) stop "make test" echoing "./RunTest".
1286     8. Added patches from David Burgess to enable PCRE to run on EBCDIC systems.
1288     9. The prototype for memmove() for systems that don't have it was using
1289        size_t, but the inclusion of the header that defines size_t was later. I've
1290        moved the #includes for the C headers earlier to avoid this.
1292    10. Added some adjustments to the code to make it easier to compiler on certain
1293        special systems:
1295          (a) Some "const" qualifiers were missing.
1296          (b) Added the macro EXPORT before all exported functions; by default this
1297              is defined to be empty.
1298          (c) Changed the dftables auxiliary program (that builds chartables.c) so
1299              that it reads its output file name as an argument instead of writing
1300              to the standard output and assuming this can be redirected.
1302    11. In UTF-8 mode, if a recursive reference (e.g. (?1)) followed a character
1303        class containing characters with values greater than 255, PCRE compilation
1304        went into a loop.
1306    12. A recursive reference to a subpattern that was within another subpattern
1307        that had a minimum quantifier of zero caused PCRE to crash. For example,
1308        (x(y(?2))z)? provoked this bug with a subject that got as far as the
1309        recursion. If the recursively-called subpattern itself had a zero repeat,
1310        that was OK.
1312    13. In pcretest, the buffer for reading a data line was set at 30K, but the
1313        buffer into which it was copied (for escape processing) was still set at
1314        1024, so long lines caused crashes.
1316    14. A pattern such as /[ab]{1,3}+/ failed to compile, giving the error
1317        "internal error: code overflow...". This applied to any character class
1318        that was followed by a possessive quantifier.
1320    15. Modified the Makefile to add libpcre.la as a prerequisite for
1321        libpcreposix.la because I was told this is needed for a parallel build to
1322        work.
1324    16. If a pattern that contained .* following optional items at the start was
1325        studied, the wrong optimizing data was generated, leading to matching
1326        errors. For example, studying /[ab]*.*c/ concluded, erroneously, that any
1327        matching string must start with a or b or c. The correct conclusion for
1328        this pattern is that a match can start with any character.
1331    Version 4.4 13-Aug-03
1332    ---------------------
1334     1. In UTF-8 mode, a character class containing characters with values between
1335        127 and 255 was not handled correctly if the compiled pattern was studied.
1336        In fixing this, I have also improved the studying algorithm for such
1337        classes (slightly).
1339     2. Three internal functions had redundant arguments passed to them. Removal
1340        might give a very teeny performance improvement.
1342     3. Documentation bug: the value of the capture_top field in a callout is *one
1343        more than* the number of the hightest numbered captured substring.
1345     4. The Makefile linked pcretest and pcregrep with -lpcre, which could result
1346        in incorrectly linking with a previously installed version. They now link
1347        explicitly with libpcre.la.
1349     5. configure.in no longer needs to recognize Cygwin specially.
1351     6. A problem in pcre.in for Windows platforms is fixed.
1353     7. If a pattern was successfully studied, and the -d (or /D) flag was given to
1354        pcretest, it used to include the size of the study block as part of its
1355        output. Unfortunately, the structure contains a field that has a different
1356        size on different hardware architectures. This meant that the tests that
1357        showed this size failed. As the block is currently always of a fixed size,
1358        this information isn't actually particularly useful in pcretest output, so
1359        I have just removed it.
1361     8. Three pre-processor statements accidentally did not start in column 1.
1362        Sadly, there are *still* compilers around that complain, even though
1363        standard C has not required this for well over a decade. Sigh.
1365     9. In pcretest, the code for checking callouts passed small integers in the
1366        callout_data field, which is a void * field. However, some picky compilers
1367        complained about the casts involved for this on 64-bit systems. Now
1368        pcretest passes the address of the small integer instead, which should get
1369        rid of the warnings.
1371    10. By default, when in UTF-8 mode, PCRE now checks for valid UTF-8 strings at
1372        both compile and run time, and gives an error if an invalid UTF-8 sequence
1373        is found. There is a option for disabling this check in cases where the
1374        string is known to be correct and/or the maximum performance is wanted.
1376    11. In response to a bug report, I changed one line in Makefile.in from
1378            -Wl,--out-implib,.libs/lib@WIN_PREFIX@pcreposix.dll.a \
1379        to
1380            -Wl,--out-implib,.libs/@WIN_PREFIX@libpcreposix.dll.a \
1382        to look similar to other lines, but I have no way of telling whether this
1383        is the right thing to do, as I do not use Windows. No doubt I'll get told
1384        if it's wrong...
1387    Version 4.3 21-May-03
1388    ---------------------
1390    1. Two instances of @WIN_PREFIX@ omitted from the Windows targets in the
1391       Makefile.
1393    2. Some refactoring to improve the quality of the code:
1395       (i)   The utf8_table... variables are now declared "const".
1397       (ii)  The code for \cx, which used the "case flipping" table to upper case
1398             lower case letters, now just substracts 32. This is ASCII-specific,
1399             but the whole concept of \cx is ASCII-specific, so it seems
1400             reasonable.
1402       (iii) PCRE was using its character types table to recognize decimal and
1403             hexadecimal digits in the pattern. This is silly, because it handles
1404             only 0-9, a-f, and A-F, but the character types table is locale-
1405             specific, which means strange things might happen. A private
1406             table is now used for this - though it costs 256 bytes, a table is
1407             much faster than multiple explicit tests. Of course, the standard
1408             character types table is still used for matching digits in subject
1409             strings against \d.
1411       (iv)  Strictly, the identifier ESC_t is reserved by POSIX (all identifiers
1412             ending in _t are). So I've renamed it as ESC_tee.
1414    3. The first argument for regexec() in the POSIX wrapper should have been
1415       defined as "const".
1417    4. Changed pcretest to use malloc() for its buffers so that they can be
1418       Electric Fenced for debugging.
1420    5. There were several places in the code where, in UTF-8 mode, PCRE would try
1421       to read one or more bytes before the start of the subject string. Often this
1422       had no effect on PCRE's behaviour, but in some circumstances it could
1423       provoke a segmentation fault.
1425    6. A lookbehind at the start of a pattern in UTF-8 mode could also cause PCRE
1426       to try to read one or more bytes before the start of the subject string.
1428    7. A lookbehind in a pattern matched in non-UTF-8 mode on a PCRE compiled with
1429       UTF-8 support could misbehave in various ways if the subject string
1430       contained bytes with the 0x80 bit set and the 0x40 bit unset in a lookbehind
1431       area. (PCRE was not checking for the UTF-8 mode flag, and trying to move
1432       back over UTF-8 characters.)
1435    Version 4.2 14-Apr-03
1436    ---------------------
1438    1. Typo "#if SUPPORT_UTF8" instead of "#ifdef SUPPORT_UTF8" fixed.
1440    2. Changes to the building process, supplied by Ronald Landheer-Cieslak
1441         [ON_WINDOWS]: new variable, "#" on non-Windows platforms
1442         [NOT_ON_WINDOWS]: new variable, "#" on Windows platforms
1443         [WIN_PREFIX]: new variable, "cyg" for Cygwin
1444         * Makefile.in: use autoconf substitution for OBJEXT, EXEEXT, BUILD_OBJEXT
1445           and BUILD_EXEEXT
1446         Note: automatic setting of the BUILD variables is not yet working
1447         set CPPFLAGS and BUILD_CPPFLAGS (but don't use yet) - should be used at
1448           compile-time but not at link-time
1449         [LINK]: use for linking executables only
1450         make different versions for Windows and non-Windows
1451         [LINKLIB]: new variable, copy of UNIX-style LINK, used for linking
1452           libraries
1453         [LINK_FOR_BUILD]: new variable
1454         [OBJEXT]: use throughout
1455         [EXEEXT]: use throughout
1456         <winshared>: new target
1457         <wininstall>: new target
1458         <dftables.o>: use native compiler
1459         <dftables>: use native linker
1460         <install>: handle Windows platform correctly
1461         <clean>: ditto
1462         <check>: ditto
1463         copy DLL to top builddir before testing
1465       As part of these changes, -no-undefined was removed again. This was reported
1466       to give trouble on HP-UX 11.0, so getting rid of it seems like a good idea
1467       in any case.
1469    3. Some tidies to get rid of compiler warnings:
1471       . In the match_data structure, match_limit was an unsigned long int, whereas
1472         match_call_count was an int. I've made them both unsigned long ints.
1474       . In pcretest the fact that a const uschar * doesn't automatically cast to
1475         a void * provoked a warning.
1477       . Turning on some more compiler warnings threw up some "shadow" variables
1478         and a few more missing casts.
1480    4. If PCRE was complied with UTF-8 support, but called without the PCRE_UTF8
1481       option, a class that contained a single character with a value between 128
1482       and 255 (e.g. /[\xFF]/) caused PCRE to crash.
1484    5. If PCRE was compiled with UTF-8 support, but called without the PCRE_UTF8
1485       option, a class that contained several characters, but with at least one
1486       whose value was between 128 and 255 caused PCRE to crash.
1489    Version 4.1 12-Mar-03
1490    ---------------------
1492    1. Compiling with gcc -pedantic found a couple of places where casts were
1493    needed, and a string in dftables.c that was longer than standard compilers are
1494    required to support.
1496    2. Compiling with Sun's compiler found a few more places where the code could
1497    be tidied up in order to avoid warnings.
1499    3. The variables for cross-compiling were called HOST_CC and HOST_CFLAGS; the
1500    first of these names is deprecated in the latest Autoconf in favour of the name
1501    CC_FOR_BUILD, because "host" is typically used to mean the system on which the
1502    compiled code will be run. I can't find a reference for HOST_CFLAGS, but by
1503    analogy I have changed it to CFLAGS_FOR_BUILD.
1505    4. Added -no-undefined to the linking command in the Makefile, because this is
1506    apparently helpful for Windows. To make it work, also added "-L. -lpcre" to the
1507    linking step for the pcreposix library.
1509    5. PCRE was failing to diagnose the case of two named groups with the same
1510    name.
1512    6. A problem with one of PCRE's optimizations was discovered. PCRE remembers a
1513    literal character that is needed in the subject for a match, and scans along to
1514    ensure that it is present before embarking on the full matching process. This
1515    saves time in cases of nested unlimited repeats that are never going to match.
1516    Problem: the scan can take a lot of time if the subject is very long (e.g.
1517    megabytes), thus penalizing straightforward matches. It is now done only if the
1518    amount of subject to be scanned is less than 1000 bytes.
1520    7. A lesser problem with the same optimization is that it was recording the
1521    first character of an anchored pattern as "needed", thus provoking a search
1522    right along the subject, even when the first match of the pattern was going to
1523    fail. The "needed" character is now not set for anchored patterns, unless it
1524    follows something in the pattern that is of non-fixed length. Thus, it still
1525    fulfils its original purpose of finding quick non-matches in cases of nested
1526    unlimited repeats, but isn't used for simple anchored patterns such as /^abc/.
1529    Version 4.0 17-Feb-03
1530    ---------------------
1532    1. If a comment in an extended regex that started immediately after a meta-item
1533    extended to the end of string, PCRE compiled incorrect data. This could lead to
1534    all kinds of weird effects. Example: /#/ was bad; /()#/ was bad; /a#/ was not.
1536    2. Moved to autoconf 2.53 and libtool 1.4.2.
1538    3. Perl 5.8 no longer needs "use utf8" for doing UTF-8 things. Consequently,
1539    the special perltest8 script is no longer needed - all the tests can be run
1540    from a single perltest script.
1542    4. From 5.004, Perl has not included the VT character (0x0b) in the set defined
1543    by \s. It has now been removed in PCRE. This means it isn't recognized as
1544    whitespace in /x regexes too, which is the same as Perl. Note that the POSIX
1545    class [:space:] *does* include VT, thereby creating a mess.
1547    5. Added the class [:blank:] (a GNU extension from Perl 5.8) to match only
1548    space and tab.
1550    6. Perl 5.005 was a long time ago. It's time to amalgamate the tests that use
1551    its new features into the main test script, reducing the number of scripts.
1553    7. Perl 5.8 has changed the meaning of patterns like /a(?i)b/. Earlier versions
1554    were backward compatible, and made the (?i) apply to the whole pattern, as if
1555    /i were given. Now it behaves more logically, and applies the option setting
1556    only to what follows. PCRE has been changed to follow suit. However, if it
1557    finds options settings right at the start of the pattern, it extracts them into
1558    the global options, as before. Thus, they show up in the info data.
1560    8. Added support for the \Q...\E escape sequence. Characters in between are
1561    treated as literals. This is slightly different from Perl in that $ and @ are
1562    also handled as literals inside the quotes. In Perl, they will cause variable
1563    interpolation. Note the following examples:
1565        Pattern            PCRE matches      Perl matches
1567        \Qabc$xyz\E        abc$xyz           abc followed by the contents of $xyz
1568        \Qabc\$xyz\E       abc\$xyz          abc\$xyz
1569        \Qabc\E\$\Qxyz\E   abc$xyz           abc$xyz
1571    For compatibility with Perl, \Q...\E sequences are recognized inside character
1572    classes as well as outside them.
1574    9. Re-organized 3 code statements in pcretest to avoid "overflow in
1575    floating-point constant arithmetic" warnings from a Microsoft compiler. Added a
1576    (size_t) cast to one statement in pcretest and one in pcreposix to avoid
1577    signed/unsigned warnings.
1579    10. SunOS4 doesn't have strtoul(). This was used only for unpicking the -o
1580    option for pcretest, so I've replaced it by a simple function that does just
1581    that job.
1583    11. pcregrep was ending with code 0 instead of 2 for the commands "pcregrep" or
1584    "pcregrep -".
1586    12. Added "possessive quantifiers" ?+, *+, ++, and {,}+ which come from Sun's
1587    Java package. This provides some syntactic sugar for simple cases of what my
1588    documentation calls "once-only subpatterns". A pattern such as x*+ is the same
1589    as (?>x*). In other words, if what is inside (?>...) is just a single repeated
1590    item, you can use this simplified notation. Note that only makes sense with
1591    greedy quantifiers. Consequently, the use of the possessive quantifier forces
1592    greediness, whatever the setting of the PCRE_UNGREEDY option.
1594    13. A change of greediness default within a pattern was not taking effect at
1595    the current level for patterns like /(b+(?U)a+)/. It did apply to parenthesized
1596    subpatterns that followed. Patterns like /b+(?U)a+/ worked because the option
1597    was abstracted outside.
1599    14. PCRE now supports the \G assertion. It is true when the current matching
1600    position is at the start point of the match. This differs from \A when the
1601    starting offset is non-zero. Used with the /g option of pcretest (or similar
1602    code), it works in the same way as it does for Perl's /g option. If all
1603    alternatives of a regex begin with \G, the expression is anchored to the start
1604    match position, and the "anchored" flag is set in the compiled expression.
1606    15. Some bugs concerning the handling of certain option changes within patterns
1607    have been fixed. These applied to options other than (?ims). For example,
1608    "a(?x: b c )d" did not match "XabcdY" but did match "Xa b c dY". It should have
1609    been the other way round. Some of this was related to change 7 above.
1611    16. PCRE now gives errors for /[.x.]/ and /[=x=]/ as unsupported POSIX
1612    features, as Perl does. Previously, PCRE gave the warnings only for /[[.x.]]/
1613    and /[[=x=]]/. PCRE now also gives an error for /[:name:]/ because it supports
1614    POSIX classes only within a class (e.g. /[[:alpha:]]/).
1616    17. Added support for Perl's \C escape. This matches one byte, even in UTF8
1617    mode. Unlike ".", it always matches newline, whatever the setting of
1618    PCRE_DOTALL. However, PCRE does not permit \C to appear in lookbehind
1619    assertions. Perl allows it, but it doesn't (in general) work because it can't
1620    calculate the length of the lookbehind. At least, that's the case for Perl
1621    5.8.0 - I've been told they are going to document that it doesn't work in
1622    future.
1624    18. Added an error diagnosis for escapes that PCRE does not support: these are
1625    \L, \l, \N, \P, \p, \U, \u, and \X.
1627    19. Although correctly diagnosing a missing ']' in a character class, PCRE was
1628    reading past the end of the pattern in cases such as /[abcd/.
1630    20. PCRE was getting more memory than necessary for patterns with classes that
1631    contained both POSIX named classes and other characters, e.g. /[[:space:]abc/.
1633    21. Added some code, conditional on #ifdef VPCOMPAT, to make life easier for
1634    compiling PCRE for use with Virtual Pascal.
1636    22. Small fix to the Makefile to make it work properly if the build is done
1637    outside the source tree.
1639    23. Added a new extension: a condition to go with recursion. If a conditional
1640    subpattern starts with (?(R) the "true" branch is used if recursion has
1641    happened, whereas the "false" branch is used only at the top level.
1643    24. When there was a very long string of literal characters (over 255 bytes
1644    without UTF support, over 250 bytes with UTF support), the computation of how
1645    much memory was required could be incorrect, leading to segfaults or other
1646    strange effects.
1648    25. PCRE was incorrectly assuming anchoring (either to start of subject or to
1649    start of line for a non-DOTALL pattern) when a pattern started with (.*) and
1650    there was a subsequent back reference to those brackets. This meant that, for
1651    example, /(.*)\d+\1/ failed to match "abc123bc". Unfortunately, it isn't
1652    possible to check for precisely this case. All we can do is abandon the
1653    optimization if .* occurs inside capturing brackets when there are any back
1654    references whatsoever. (See below for a better fix that came later.)
1656    26. The handling of the optimization for finding the first character of a
1657    non-anchored pattern, and for finding a character that is required later in the
1658    match were failing in some cases. This didn't break the matching; it just
1659    failed to optimize when it could. The way this is done has been re-implemented.
1661    27. Fixed typo in error message for invalid (?R item (it said "(?p").
1663    28. Added a new feature that provides some of the functionality that Perl
1664    provides with (?{...}). The facility is termed a "callout". The way it is done
1665    in PCRE is for the caller to provide an optional function, by setting
1666    pcre_callout to its entry point. Like pcre_malloc and pcre_free, this is a
1667    global variable. By default it is unset, which disables all calling out. To get
1668    the function called, the regex must include (?C) at appropriate points. This
1669    is, in fact, equivalent to (?C0), and any number <= 255 may be given with (?C).
1670    This provides a means of identifying different callout points. When PCRE
1671    reaches such a point in the regex, if pcre_callout has been set, the external
1672    function is called. It is provided with data in a structure called
1673    pcre_callout_block, which is defined in pcre.h. If the function returns 0,
1674    matching continues; if it returns a non-zero value, the match at the current
1675    point fails. However, backtracking will occur if possible. [This was changed
1676    later and other features added - see item 49 below.]
1678    29. pcretest is upgraded to test the callout functionality. It provides a
1679    callout function that displays information. By default, it shows the start of
1680    the match and the current position in the text. There are some new data escapes
1681    to vary what happens:
1683        \C+         in addition, show current contents of captured substrings
1684        \C-         do not supply a callout function
1685        \C!n        return 1 when callout number n is reached
1686        \C!n!m      return 1 when callout number n is reached for the mth time
1688    30. If pcregrep was called with the -l option and just a single file name, it
1689    output "<stdin>" if a match was found, instead of the file name.
1691    31. Improve the efficiency of the POSIX API to PCRE. If the number of capturing
1692    slots is less than POSIX_MALLOC_THRESHOLD, use a block on the stack to pass to
1693    pcre_exec(). This saves a malloc/free per call. The default value of
1694    POSIX_MALLOC_THRESHOLD is 10; it can be changed by --with-posix-malloc-threshold
1695    when configuring.
1697    32. The default maximum size of a compiled pattern is 64K. There have been a
1698    few cases of people hitting this limit. The code now uses macros to handle the
1699    storing of links as offsets within the compiled pattern. It defaults to 2-byte
1700    links, but this can be changed to 3 or 4 bytes by --with-link-size when
1701    configuring. Tests 2 and 5 work only with 2-byte links because they output
1702    debugging information about compiled patterns.
1704    33. Internal code re-arrangements:
1706    (a) Moved the debugging function for printing out a compiled regex into
1707        its own source file (printint.c) and used #include to pull it into
1708        pcretest.c and, when DEBUG is defined, into pcre.c, instead of having two
1709        separate copies.
1711    (b) Defined the list of op-code names for debugging as a macro in
1712        internal.h so that it is next to the definition of the opcodes.
1714    (c) Defined a table of op-code lengths for simpler skipping along compiled
1715        code. This is again a macro in internal.h so that it is next to the
1716        definition of the opcodes.
1718    34. Added support for recursive calls to individual subpatterns, along the
1719    lines of Robin Houston's patch (but implemented somewhat differently).
1721    35. Further mods to the Makefile to help Win32. Also, added code to pcregrep to
1722    allow it to read and process whole directories in Win32. This code was
1723    contributed by Lionel Fourquaux; it has not been tested by me.
1725    36. Added support for named subpatterns. The Python syntax (?P<name>...) is
1726    used to name a group. Names consist of alphanumerics and underscores, and must
1727    be unique. Back references use the syntax (?P=name) and recursive calls use
1728    (?P>name) which is a PCRE extension to the Python extension. Groups still have
1729    numbers. The function pcre_fullinfo() can be used after compilation to extract
1730    a name/number map. There are three relevant calls:
1732      PCRE_INFO_NAMEENTRYSIZE        yields the size of each entry in the map
1733      PCRE_INFO_NAMECOUNT            yields the number of entries
1734      PCRE_INFO_NAMETABLE            yields a pointer to the map.
1736    The map is a vector of fixed-size entries. The size of each entry depends on
1737    the length of the longest name used. The first two bytes of each entry are the
1738    group number, most significant byte first. There follows the corresponding
1739    name, zero terminated. The names are in alphabetical order.
1741    37. Make the maximum literal string in the compiled code 250 for the non-UTF-8
1742    case instead of 255. Making it the same both with and without UTF-8 support
1743    means that the same test output works with both.
1745    38. There was a case of malloc(0) in the POSIX testing code in pcretest. Avoid
1746    calling malloc() with a zero argument.
1748    39. Change 25 above had to resort to a heavy-handed test for the .* anchoring
1749    optimization. I've improved things by keeping a bitmap of backreferences with
1750    numbers 1-31 so that if .* occurs inside capturing brackets that are not in
1751    fact referenced, the optimization can be applied. It is unlikely that a
1752    relevant occurrence of .* (i.e. one which might indicate anchoring or forcing
1753    the match to follow \n) will appear inside brackets with a number greater than
1754    31, but if it does, any back reference > 31 suppresses the optimization.
1756    40. Added a new compile-time option PCRE_NO_AUTO_CAPTURE. This has the effect
1757    of disabling numbered capturing parentheses. Any opening parenthesis that is
1758    not followed by ? behaves as if it were followed by ?: but named parentheses
1759    can still be used for capturing (and they will acquire numbers in the usual
1760    way).
1762    41. Redesigned the return codes from the match() function into yes/no/error so
1763    that errors can be passed back from deep inside the nested calls. A malloc
1764    failure while inside a recursive subpattern call now causes the
1765    PCRE_ERROR_NOMEMORY return instead of quietly going wrong.
1767    42. It is now possible to set a limit on the number of times the match()
1768    function is called in a call to pcre_exec(). This facility makes it possible to
1769    limit the amount of recursion and backtracking, though not in a directly
1770    obvious way, because the match() function is used in a number of different
1771    circumstances. The count starts from zero for each position in the subject
1772    string (for non-anchored patterns). The default limit is, for compatibility, a
1773    large number, namely 10 000 000. You can change this in two ways:
1775    (a) When configuring PCRE before making, you can use --with-match-limit=n
1776        to set a default value for the compiled library.
1778    (b) For each call to pcre_exec(), you can pass a pcre_extra block in which
1779        a different value is set. See 45 below.
1781    If the limit is exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT.
1783    43. Added a new function pcre_config(int, void *) to enable run-time extraction
1784    of things that can be changed at compile time. The first argument specifies
1785    what is wanted and the second points to where the information is to be placed.
1786    The current list of available information is:
1788      PCRE_CONFIG_UTF8
1790    The output is an integer that is set to one if UTF-8 support is available;
1791    otherwise it is set to zero.
1795    The output is an integer that it set to the value of the code that is used for
1796    newline. It is either LF (10) or CR (13).
1800    The output is an integer that contains the number of bytes used for internal
1801    linkage in compiled expressions. The value is 2, 3, or 4. See item 32 above.
1805    The output is an integer that contains the threshold above which the POSIX
1806    interface uses malloc() for output vectors. See item 31 above.
1810    The output is an unsigned integer that contains the default limit of the number
1811    of match() calls in a pcre_exec() execution. See 42 above.
1813    44. pcretest has been upgraded by the addition of the -C option. This causes it
1814    to extract all the available output from the new pcre_config() function, and to
1815    output it. The program then exits immediately.
1817    45. A need has arisen to pass over additional data with calls to pcre_exec() in
1818    order to support additional features. One way would have been to define
1819    pcre_exec2() (for example) with extra arguments, but this would not have been
1820    extensible, and would also have required all calls to the original function to
1821    be mapped to the new one. Instead, I have chosen to extend the mechanism that
1822    is used for passing in "extra" data from pcre_study().
1824    The pcre_extra structure is now exposed and defined in pcre.h. It currently
1825    contains the following fields:
1827      flags         a bitmap indicating which of the following fields are set
1828      study_data    opaque data from pcre_study()
1829      match_limit   a way of specifying a limit on match() calls for a specific
1830                      call to pcre_exec()
1831      callout_data  data for callouts (see 49 below)
1833    The flag bits are also defined in pcre.h, and are
1839    The pcre_study() function now returns one of these new pcre_extra blocks, with
1840    the actual study data pointed to by the study_data field, and the
1841    PCRE_EXTRA_STUDY_DATA flag set. This can be passed directly to pcre_exec() as
1842    before. That is, this change is entirely upwards-compatible and requires no
1843    change to existing code.
1845    If you want to pass in additional data to pcre_exec(), you can either place it
1846    in a pcre_extra block provided by pcre_study(), or create your own pcre_extra
1847    block.
1849    46. pcretest has been extended to test the PCRE_EXTRA_MATCH_LIMIT feature. If a
1850    data string contains the escape sequence \M, pcretest calls pcre_exec() several
1851    times with different match limits, until it finds the minimum value needed for
1852    pcre_exec() to complete. The value is then output. This can be instructive; for
1853    most simple matches the number is quite small, but for pathological cases it
1854    gets very large very quickly.
1856    47. There's a new option for pcre_fullinfo() called PCRE_INFO_STUDYSIZE. It
1857    returns the size of the data block pointed to by the study_data field in a
1858    pcre_extra block, that is, the value that was passed as the argument to
1859    pcre_malloc() when PCRE was getting memory in which to place the information
1860    created by pcre_study(). The fourth argument should point to a size_t variable.
1861    pcretest has been extended so that this information is shown after a successful
1862    pcre_study() call when information about the compiled regex is being displayed.
1864    48. Cosmetic change to Makefile: there's no need to have / after $(DESTDIR)
1865    because what follows is always an absolute path. (Later: it turns out that this
1866    is more than cosmetic for MinGW, because it doesn't like empty path
1867    components.)
1869    49. Some changes have been made to the callout feature (see 28 above):
1871    (i)  A callout function now has three choices for what it returns:
1873           0  =>  success, carry on matching
1874         > 0  =>  failure at this point, but backtrack if possible
1875         < 0  =>  serious error, return this value from pcre_exec()
1877         Negative values should normally be chosen from the set of PCRE_ERROR_xxx
1878         values. In particular, returning PCRE_ERROR_NOMATCH forces a standard
1879         "match failed" error. The error number PCRE_ERROR_CALLOUT is reserved for
1880         use by callout functions. It will never be used by PCRE itself.
1882    (ii) The pcre_extra structure (see 45 above) has a void * field called
1883         callout_data, with corresponding flag bit PCRE_EXTRA_CALLOUT_DATA. The
1884         pcre_callout_block structure has a field of the same name. The contents of
1885         the field passed in the pcre_extra structure are passed to the callout
1886         function in the corresponding field in the callout block. This makes it
1887         easier to use the same callout-containing regex from multiple threads. For
1888         testing, the pcretest program has a new data escape
1890           \C*n        pass the number n (may be negative) as callout_data
1892         If the callout function in pcretest receives a non-zero value as
1893         callout_data, it returns that value.
1895    50. Makefile wasn't handling CFLAGS properly when compiling dftables. Also,
1896    there were some redundant $(CFLAGS) in commands that are now specified as
1897    $(LINK), which already includes $(CFLAGS).
1899    51. Extensions to UTF-8 support are listed below. These all apply when (a) PCRE
1900    has been compiled with UTF-8 support *and* pcre_compile() has been compiled
1901    with the PCRE_UTF8 flag. Patterns that are compiled without that flag assume
1902    one-byte characters throughout. Note that case-insensitive matching applies
1903    only to characters whose values are less than 256. PCRE doesn't support the
1904    notion of cases for higher-valued characters.
1906    (i)   A character class whose characters are all within 0-255 is handled as
1907          a bit map, and the map is inverted for negative classes. Previously, a
1908          character > 255 always failed to match such a class; however it should
1909          match if the class was a negative one (e.g. [^ab]). This has been fixed.
1911    (ii)  A negated character class with a single character < 255 is coded as
1912          "not this character" (OP_NOT). This wasn't working properly when the test
1913          character was multibyte, either singly or repeated.
1915    (iii) Repeats of multibyte characters are now handled correctly in UTF-8
1916          mode, for example: \x{100}{2,3}.
1918    (iv)  The character escapes \b, \B, \d, \D, \s, \S, \w, and \W (either
1919          singly or repeated) now correctly test multibyte characters. However,
1920          PCRE doesn't recognize any characters with values greater than 255 as
1921          digits, spaces, or word characters. Such characters always match \D, \S,
1922          and \W, and never match \d, \s, or \w.
1924    (v)   Classes may now contain characters and character ranges with values
1925          greater than 255. For example: [ab\x{100}-\x{400}].
1927    (vi)  pcregrep now has a --utf-8 option (synonym -u) which makes it call
1928          PCRE in UTF-8 mode.
1930    52. The info request value PCRE_INFO_FIRSTCHAR has been renamed
1931    PCRE_INFO_FIRSTBYTE because it is a byte value. However, the old name is
1932    retained for backwards compatibility. (Note that LASTLITERAL is also a byte
1933    value.)
1935    53. The single man page has become too large. I have therefore split it up into
1936    a number of separate man pages. These also give rise to individual HTML pages;
1937    these are now put in a separate directory, and there is an index.html page that
1938    lists them all. Some hyperlinking between the pages has been installed.
1940    54. Added convenience functions for handling named capturing parentheses.
1942    55. Unknown escapes inside character classes (e.g. [\M]) and escapes that
1943    aren't interpreted therein (e.g. [\C]) are literals in Perl. This is now also
1944    true in PCRE, except when the PCRE_EXTENDED option is set, in which case they
1945    are faulted.
1947    56. Introduced HOST_CC and HOST_CFLAGS which can be set in the environment when
1948    calling configure. These values are used when compiling the dftables.c program
1949    which is run to generate the source of the default character tables. They
1950    default to the values of CC and CFLAGS. If you are cross-compiling PCRE,
1951    you will need to set these values.
1953    57. Updated the building process for Windows DLL, as provided by Fred Cox.
1956    Version 3.9 02-Jan-02
1957    ---------------------
1959    1. A bit of extraneous text had somehow crept into the pcregrep documentation.
1961    2. If --disable-static was given, the building process failed when trying to
1962    build pcretest and pcregrep. (For some reason it was using libtool to compile
1963    them, which is not right, as they aren't part of the library.)
1966    Version 3.8 18-Dec-01
1967    ---------------------
1969    1. The experimental UTF-8 code was completely screwed up. It was packing the
1970    bytes in the wrong order. How dumb can you get?
1973    Version 3.7 29-Oct-01
1974    ---------------------
1976    1. In updating pcretest to check change 1 of version 3.6, I screwed up.
1977    This caused pcretest, when used on the test data, to segfault. Unfortunately,
1978    this didn't happen under Solaris 8, where I normally test things.
1980    2. The Makefile had to be changed to make it work on BSD systems, where 'make'
1981    doesn't seem to recognize that ./xxx and xxx are the same file. (This entry
1982    isn't in ChangeLog distributed with 3.7 because I forgot when I hastily made
1983    this fix an hour or so after the initial 3.7 release.)
1986    Version 3.6 23-Oct-01
1987    ---------------------
1989    1. Crashed with /(sens|respons)e and \1ibility/ and "sense and sensibility" if
1990    offsets passed as NULL with zero offset count.
1992    2. The config.guess and config.sub files had not been updated when I moved to
1993    the latest autoconf.
1996    Version 3.5 15-Aug-01
1997    ---------------------
1999    1. Added some missing #if !defined NOPOSIX conditionals in pcretest.c that
2000    had been forgotten.
2002    2. By using declared but undefined structures, we can avoid using "void"
2003    definitions in pcre.h while keeping the internal definitions of the structures
2004    private.
2006    3. The distribution is now built using autoconf 2.50 and libtool 1.4. From a
2007    user point of view, this means that both static and shared libraries are built
2008    by default, but this can be individually controlled. More of the work of
2009    handling this static/shared cases is now inside libtool instead of PCRE's make
2010    file.
2012    4. The pcretest utility is now installed along with pcregrep because it is
2013    useful for users (to test regexs) and by doing this, it automatically gets
2014    relinked by libtool. The documentation has been turned into a man page, so
2015    there are now .1, .txt, and .html versions in /doc.
2017    5. Upgrades to pcregrep:
2018       (i)   Added long-form option names like gnu grep.
2019       (ii)  Added --help to list all options with an explanatory phrase.
2020       (iii) Added -r, --recursive to recurse into sub-directories.
2021       (iv)  Added -f, --file to read patterns from a file.
2023    6. pcre_exec() was referring to its "code" argument before testing that
2024    argument for NULL (and giving an error if it was NULL).
2026    7. Upgraded Makefile.in to allow for compiling in a different directory from
2027    the source directory.
2029    8. Tiny buglet in pcretest: when pcre_fullinfo() was called to retrieve the
2030    options bits, the pointer it was passed was to an int instead of to an unsigned
2031    long int. This mattered only on 64-bit systems.
2033    9. Fixed typo (3.4/1) in pcre.h again. Sigh. I had changed pcre.h (which is
2034    generated) instead of pcre.in, which it its source. Also made the same change
2035    in several of the .c files.
2037    10. A new release of gcc defines printf() as a macro, which broke pcretest
2038    because it had an ifdef in the middle of a string argument for printf(). Fixed
2039    by using separate calls to printf().
2041    11. Added --enable-newline-is-cr and --enable-newline-is-lf to the configure
2042    script, to force use of CR or LF instead of \n in the source. On non-Unix
2043    systems, the value can be set in config.h.
2045    12. The limit of 200 on non-capturing parentheses is a _nesting_ limit, not an
2046    absolute limit. Changed the text of the error message to make this clear, and
2047    likewise updated the man page.
2049    13. The limit of 99 on the number of capturing subpatterns has been removed.
2050    The new limit is 65535, which I hope will not be a "real" limit.
2053    Version 3.4 22-Aug-00
2054    ---------------------
2056    1. Fixed typo in pcre.h: unsigned const char * changed to const unsigned char *.
2058    2. Diagnose condition (?(0) as an error instead of crashing on matching.
2061    Version 3.3 01-Aug-00
2062    ---------------------
2064    1. If an octal character was given, but the value was greater than \377, it
2065    was not getting masked to the least significant bits, as documented. This could
2066    lead to crashes in some systems.
2068    2. Perl 5.6 (if not earlier versions) accepts classes like [a-\d] and treats
2069    the hyphen as a literal. PCRE used to give an error; it now behaves like Perl.
2071    3. Added the functions pcre_free_substring() and pcre_free_substring_list().
2072    These just pass their arguments on to (pcre_free)(), but they are provided
2073    because some uses of PCRE bind it to non-C systems that can call its functions,
2074    but cannot call free() or pcre_free() directly.
2076    4. Add "make test" as a synonym for "make check". Corrected some comments in
2077    the Makefile.
2079    5. Add $(DESTDIR)/ in front of all the paths in the "install" target in the
2080    Makefile.
2082    6. Changed the name of pgrep to pcregrep, because Solaris has introduced a
2083    command called pgrep for grepping around the active processes.
2085    7. Added the beginnings of support for UTF-8 character strings.
2087    8. Arranged for the Makefile to pass over the settings of CC, CFLAGS, and
2088    RANLIB to ./ltconfig so that they are used by libtool. I think these are all
2089    the relevant ones. (AR is not passed because ./ltconfig does its own figuring
2090    out for the ar command.)
2093    Version 3.2 12-May-00
2094    ---------------------
2096    This is purely a bug fixing release.
2098    1. If the pattern /((Z)+|A)*/ was matched agained ZABCDEFG it matched Z instead
2099    of ZA. This was just one example of several cases that could provoke this bug,
2100    which was introduced by change 9 of version 2.00. The code for breaking
2101    infinite loops after an iteration that matches an empty string was't working
2102    correctly.
2104    2. The pcretest program was not imitating Perl correctly for the pattern /a*/g
2105    when matched against abbab (for example). After matching an empty string, it
2106    wasn't forcing anchoring when setting PCRE_NOTEMPTY for the next attempt; this
2107    caused it to match further down the string than it should.
2109    3. The code contained an inclusion of sys/types.h. It isn't clear why this
2110    was there because it doesn't seem to be needed, and it causes trouble on some
2111    systems, as it is not a Standard C header. It has been removed.
2113    4. Made 4 silly changes to the source to avoid stupid compiler warnings that
2114    were reported on the Macintosh. The changes were from
2116      while ((c = *(++ptr)) != 0 && c != '\n');
2117    to
2118      while ((c = *(++ptr)) != 0 && c != '\n') ;
2120    Totally extraordinary, but if that's what it takes...
2122    5. PCRE is being used in one environment where neither memmove() nor bcopy() is
2123    available. Added HAVE_BCOPY and an autoconf test for it; if neither
2124    HAVE_MEMMOVE nor HAVE_BCOPY is set, use a built-in emulation function which
2125    assumes the way PCRE uses memmove() (always moving upwards).
2127    6. PCRE is being used in one environment where strchr() is not available. There
2128    was only one use in pcre.c, and writing it out to avoid strchr() probably gives
2129    faster code anyway.
2132    Version 3.1 09-Feb-00
2133    ---------------------
2135    The only change in this release is the fixing of some bugs in Makefile.in for
2136    the "install" target:
2138    (1) It was failing to install pcreposix.h.
2140    (2) It was overwriting the pcre.3 man page with the pcreposix.3 man page.
2143    Version 3.0 01-Feb-00
2144    ---------------------
2146    1. Add support for the /+ modifier to perltest (to output $` like it does in
2147    pcretest).
2149    2. Add support for the /g modifier to perltest.
2151    3. Fix pcretest so that it behaves even more like Perl for /g when the pattern
2152    matches null strings.
2154    4. Fix perltest so that it doesn't do unwanted things when fed an empty
2155    pattern. Perl treats empty patterns specially - it reuses the most recent
2156    pattern, which is not what we want. Replace // by /(?#)/ in order to avoid this
2157    effect.
2159    5. The POSIX interface was broken in that it was just handing over the POSIX
2160    captured string vector to pcre_exec(), but (since release 2.00) PCRE has
2161    required a bigger vector, with some working space on the end. This means that
2162    the POSIX wrapper now has to get and free some memory, and copy the results.
2164    6. Added some simple autoconf support, placing the test data and the
2165    documentation in separate directories, re-organizing some of the
2166    information files, and making it build pcre-config (a GNU standard). Also added
2167    libtool support for building PCRE as a shared library, which is now the
2168    default.
2170    7. Got rid of the leading zero in the definition of PCRE_MINOR because 08 and
2171    09 are not valid octal constants. Single digits will be used for minor values
2172    less than 10.
2174    8. Defined REG_EXTENDED and REG_NOSUB as zero in the POSIX header, so that
2175    existing programs that set these in the POSIX interface can use PCRE without
2176    modification.
2178    9. Added a new function, pcre_fullinfo() with an extensible interface. It can
2179    return all that pcre_info() returns, plus additional data. The pcre_info()
2180    function is retained for compatibility, but is considered to be obsolete.
2182    10. Added experimental recursion feature (?R) to handle one common case that
2183    Perl 5.6 will be able to do with (?p{...}).
2185    11. Added support for POSIX character classes like [:alpha:], which Perl is
2186    adopting.
2189    Version 2.08 31-Aug-99
2190    ----------------------
2192    1. When startoffset was not zero and the pattern began with ".*", PCRE was not
2193    trying to match at the startoffset position, but instead was moving forward to
2194    the next newline as if a previous match had failed.
2196    2. pcretest was not making use of PCRE_NOTEMPTY when repeating for /g and /G,
2197    and could get into a loop if a null string was matched other than at the start
2198    of the subject.
2200    3. Added definitions of PCRE_MAJOR and PCRE_MINOR to pcre.h so the version can
2201    be distinguished at compile time, and for completeness also added PCRE_DATE.
2203    5. Added Paul Sokolovsky's minor changes to make it easy to compile a Win32 DLL
2204    in GnuWin32 environments.
2207    Version 2.07 29-Jul-99
2208    ----------------------
2210    1. The documentation is now supplied in plain text form and HTML as well as in
2211    the form of man page sources.
2213    2. C++ compilers don't like assigning (void *) values to other pointer types.
2214    In particular this affects malloc(). Although there is no problem in Standard
2215    C, I've put in casts to keep C++ compilers happy.
2217    3. Typo on pcretest.c; a cast of (unsigned char *) in the POSIX regexec() call
2218    should be (const char *).
2220    4. If NOPOSIX is defined, pcretest.c compiles without POSIX support. This may
2221    be useful for non-Unix systems who don't want to bother with the POSIX stuff.
2222    However, I haven't made this a standard facility. The documentation doesn't
2223    mention it, and the Makefile doesn't support it.
2225    5. The Makefile now contains an "install" target, with editable destinations at
2226    the top of the file. The pcretest program is not installed.
2228    6. pgrep -V now gives the PCRE version number and date.
2230    7. Fixed bug: a zero repetition after a literal string (e.g. /abcde{0}/) was
2231    causing the entire string to be ignored, instead of just the last character.
2233    8. If a pattern like /"([^\\"]+|\\.)*"/ is applied in the normal way to a
2234    non-matching string, it can take a very, very long time, even for strings of
2235    quite modest length, because of the nested recursion. PCRE now does better in
2236    some of these cases. It does this by remembering the last required literal
2237    character in the pattern, and pre-searching the subject to ensure it is present
2238    before running the real match. In other words, it applies a heuristic to detect
2239    some types of certain failure quickly, and in the above example, if presented
2240    with a string that has no trailing " it gives "no match" very quickly.
2242    9. A new runtime option PCRE_NOTEMPTY causes null string matches to be ignored;
2243    other alternatives are tried instead.
2246    Version 2.06 09-Jun-99
2247    ----------------------
2249    1. Change pcretest's output for amount of store used to show just the code
2250    space, because the remainder (the data block) varies in size between 32-bit and
2251    64-bit systems.
2253    2. Added an extra argument to pcre_exec() to supply an offset in the subject to
2254    start matching at. This allows lookbehinds to work when searching for multiple
2255    occurrences in a string.
2257    3. Added additional options to pcretest for testing multiple occurrences:
2259       /+   outputs the rest of the string that follows a match
2260       /g   loops for multiple occurrences, using the new startoffset argument
2261       /G   loops for multiple occurrences by passing an incremented pointer
2263    4. PCRE wasn't doing the "first character" optimization for patterns starting
2264    with \b or \B, though it was doing it for other lookbehind assertions. That is,
2265    it wasn't noticing that a match for a pattern such as /\bxyz/ has to start with
2266    the letter 'x'. On long subject strings, this gives a significant speed-up.
2269  Version 2.05 21-Apr-99  Version 2.05 21-Apr-99
2270  ----------------------  ----------------------

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