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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
4    Version 7.2 05-June-07
5    ---------------------
7     1. If the fr_FR locale cannot be found for test 3, try the "french" locale,
8        which is apparently normally available under Windows.
10     2. Re-jig the pcregrep tests with different newline settings in an attempt
11        to make them independent of the local environment's newline setting.
13     3. Add code to configure.ac to remove -g from the CFLAGS default settings.
15     4. Some of the "internals" tests were previously cut out when the link size
16        was not 2, because the output contained actual offsets. The recent new
17        "Z" feature of pcretest means that these can be cut out, making the tests
18        usable with all link sizes.
20     5. Implemented Stan Switzer's goto replacement for longjmp() when not using
21        stack recursion. This gives a massive performance boost under BSD, but just
22        a small improvement under Linux. However, it saves one field in the frame
23        in all cases.
25     6. Added more features from the forthcoming Perl 5.10:
27        (a) (?-n) (where n is a string of digits) is a relative subroutine or
28            recursion call. It refers to the nth most recently opened parentheses.
30        (b) (?+n) is also a relative subroutine call; it refers to the nth next
31            to be opened parentheses.
33        (c) Conditions that refer to capturing parentheses can be specified
34            relatively, for example, (?(-2)... or (?(+3)...
36        (d) \K resets the start of the current match so that everything before
37            is not part of it.
39        (e) \k{name} is synonymous with \k<name> and \k'name' (.NET compatible).
41        (f) \g{name} is another synonym - part of Perl 5.10's unification of
42            reference syntax.
44        (g) (?| introduces a group in which the numbering of parentheses in each
45            alternative starts with the same number.
47     7. Added two new calls to pcre_fullinfo(): PCRE_INFO_OKPARTIAL and
50     8. A pattern such as  (.*(.)?)*  caused pcre_exec() to fail by either not
51        terminating or by crashing. Diagnosed by Viktor Griph; it was in the code
52        for detecting groups that can match an empty string.
54     9. A pattern with a very large number of alternatives (more than several
55        hundred) was running out of internal workspace during the pre-compile
56        phase, where pcre_compile() figures out how much memory will be needed. A
57        bit of new cunning has reduced the workspace needed for groups with
58        alternatives. The 1000-alternative test pattern now uses 12 bytes of
59        workspace instead of running out of the 4096 that are available.
61    10. Inserted some missing (unsigned int) casts to get rid of compiler warnings.
64    Version 7.1 24-Apr-07
65    ---------------------
67     1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
68        that is more "standard", making use of automake and other Autotools. There
69        is some re-arrangement of the files and adjustment of comments consequent
70        on this.
72     2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
73        for recursive directory scanning broke on some systems because the files
74        are not scanned in any specific order and on different systems the order
75        was different. A call to "sort" has been inserted into RunGrepTest for the
76        approprate test as a short-term fix. In the longer term there may be an
77        alternative.
79     3. I had an email from Eric Raymond about problems translating some of PCRE's
80        man pages to HTML (despite the fact that I distribute HTML pages, some
81        people do their own conversions for various reasons). The problems
82        concerned the use of low-level troff macros .br and .in. I have therefore
83        removed all such uses from the man pages (some were redundant, some could
84        be replaced by .nf/.fi pairs). The 132html script that I use to generate
85        HTML has been updated to handle .nf/.fi and to complain if it encounters
86        .br or .in.
88     4. Updated comments in configure.ac that get placed in config.h.in and also
89        arranged for config.h to be included in the distribution, with the name
90        config.h.generic, for the benefit of those who have to compile without
91        Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
93     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
94        Weber: (1) pcre_internal.h was missing some function renames; (2) updated
95        makevp.bat for the current PCRE, using the additional files
96        makevp_c.txt, makevp_l.txt, and pcregexp.pas.
98     6. A Windows user reported a minor discrepancy with test 2, which turned out
99        to be caused by a trailing space on an input line that had got lost in his
100        copy. The trailing space was an accident, so I've just removed it.
102     7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
103        that is needed.
105     8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
106        as "const" (a) because they are and (b) because it helps the PHP
107        maintainers who have recently made a script to detect big data structures
108        in the php code that should be moved to the .rodata section. I remembered
109        to update Builducptable as well, so it won't revert if ucptable.h is ever
110        re-created.
112     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
113        pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
114        order to be able to cut out the UTF-8 tables in the latter when UTF-8
115        support is not required. This saves 1.5-2K of code, which is important in
116        some applications.
118        Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
119        so as not to refer to the tables, even though these functions will never be
120        called when UTF-8 support is disabled. Otherwise there are problems with a
121        shared library.
123    10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
125        (a) It was defining its arguments as char * instead of void *.
127        (b) It was assuming that all moves were upwards in memory; this was true
128            a long time ago when I wrote it, but is no longer the case.
130        The emulated memove() is provided for those environments that have neither
131        memmove() nor bcopy(). I didn't think anyone used it these days, but that
132        is clearly not the case, as these two bugs were recently reported.
134    11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
135        and Detrail to create the HTML documentation, the .txt form of the man
136        pages, and it removes trailing spaces from listed files. It also creates
137        pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
138        case, it wraps all the #defines with #ifndefs. This script should be run
139        before "make dist".
141    12. Fixed two fairly obscure bugs concerned with quantified caseless matching
142        with Unicode property support.
144        (a) For a maximizing quantifier, if the two different cases of the
145            character were of different lengths in their UTF-8 codings (there are
146            some cases like this - I found 11), and the matching function had to
147            back up over a mixture of the two cases, it incorrectly assumed they
148            were both the same length.
150        (b) When PCRE was configured to use the heap rather than the stack for
151            recursion during matching, it was not correctly preserving the data for
152            the other case of a UTF-8 character when checking ahead for a match
153            while processing a minimizing repeat. If the check also involved
154            matching a wide character, but failed, corruption could cause an
155            erroneous result when trying to check for a repeat of the original
156            character.
158    13. Some tidying changes to the testing mechanism:
160        (a) The RunTest script now detects the internal link size and whether there
161            is UTF-8 and UCP support by running ./pcretest -C instead of relying on
162            values substituted by "configure". (The RunGrepTest script already did
163            this for UTF-8.) The configure.ac script no longer substitutes the
164            relevant variables.
166        (b) The debugging options /B and /D in pcretest show the compiled bytecode
167            with length and offset values. This means that the output is different
168            for different internal link sizes. Test 2 is skipped for link sizes
169            other than 2 because of this, bypassing the problem. Unfortunately,
170            there was also a test in test 3 (the locale tests) that used /B and
171            failed for link sizes other than 2. Rather than cut the whole test out,
172            I have added a new /Z option to pcretest that replaces the length and
173            offset values with spaces. This is now used to make test 3 independent
174            of link size. (Test 2 will be tidied up later.)
176    14. If erroroffset was passed as NULL to pcre_compile, it provoked a
177        segmentation fault instead of returning the appropriate error message.
179    15. In multiline mode when the newline sequence was set to "any", the pattern
180        ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
181        This doesn't seem right; it now treats the CRLF combination as the line
182        ending, and so does not match in that case. It's only a pattern such as ^$
183        that would hit this one: something like ^ABC$ would have failed after \r
184        and then tried again after \r\n.
186    16. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
187        in an attempt to make files that differ only in their line terminators
188        compare equal. This works on Linux.
190    17. Under certain error circumstances pcregrep might try to free random memory
191        as it exited. This is now fixed, thanks to valgrind.
193    19. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
194        "abc\r\n\r\n", it found an unwanted second match after the second \r. This
195        was because its rules for how to advance for /g after matching an empty
196        string at the end of a line did not allow for this case. They now check for
197        it specially.
199    20. pcretest is supposed to handle patterns and data of any length, by
200        extending its buffers when necessary. It was getting this wrong when the
201        buffer for a data line had to be extended.
203    21. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or
204        CRLF as a newline sequence.
206    22. Code for handling Unicode properties in pcre_dfa_exec() wasn't being cut
207        out by #ifdef SUPPORT_UCP. This did no harm, as it could never be used, but
208        I have nevertheless tidied it up.
210    23. Added some casts to kill warnings from HP-UX ia64 compiler.
212    24. Added a man page for pcre-config.
215    Version 7.0 19-Dec-06
216    ---------------------
218     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
219        moving to gcc 4.1.1.
221     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
222        sys/time.h, which is documented as needed for this function. It doesn't
223        seem to matter on Linux, but it showed up on some releases of OS X.
225     3. It seems that there are systems where bytes whose values are greater than
226        127 match isprint() in the "C" locale. The "C" locale should be the
227        default when a C program starts up. In most systems, only ASCII printing
228        characters match isprint(). This difference caused the output from pcretest
229        to vary, making some of the tests fail. I have changed pcretest so that:
231        (a) When it is outputting text in the compiled version of a pattern, bytes
232            other than 32-126 are always shown as hex escapes.
234        (b) When it is outputting text that is a matched part of a subject string,
235            it does the same, unless a different locale has been set for the match
236            (using the /L modifier). In this case, it uses isprint() to decide.
238     4. Fixed a major bug that caused incorrect computation of the amount of memory
239        required for a compiled pattern when options that changed within the
240        pattern affected the logic of the preliminary scan that determines the
241        length. The relevant options are -x, and -i in UTF-8 mode. The result was
242        that the computed length was too small. The symptoms of this bug were
243        either the PCRE error "internal error: code overflow" from pcre_compile(),
244        or a glibc crash with a message such as "pcretest: free(): invalid next
245        size (fast)". Examples of patterns that provoked this bug (shown in
246        pcretest format) are:
248          /(?-x: )/x
249          /(?x)(?-x: \s*#\s*)/
250          /((?i)[\x{c0}])/8
251          /(?i:[\x{c0}])/8
253        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
254        is now done differently.
256     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
257        wrapper classes; (b) implement a new function in the C++ scanner that is
258        more efficient than the old way of doing things because it avoids levels of
259        recursion in the regex matching; (c) add a paragraph to the documentation
260        for the FullMatch() function.
262     6. The escape sequence \n was being treated as whatever was defined as
263        "newline". Not only was this contrary to the documentation, which states
264        that \n is character 10 (hex 0A), but it also went horribly wrong when
265        "newline" was defined as CRLF. This has been fixed.
267     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
268        was being set to -1 for the "end of line" case (supposedly a value that no
269        character can have). Though this value is never used (the check for end of
270        line is "zero bytes in current character"), it caused compiler complaints.
271        I've changed it to 0xffffffff.
273     8. In pcre_version.c, the version string was being built by a sequence of
274        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
275        string (as it is for production releases) called a macro with an empty
276        argument. The C standard says the result of this is undefined. The gcc
277        compiler treats it as an empty string (which was what was wanted) but it is
278        reported that Visual C gives an error. The source has been hacked around to
279        avoid this problem.
281     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
282        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
283        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
284        of them did).
286    10. Originally, pcretest opened its input and output without "b"; then I was
287        told that "b" was needed in some environments, so it was added for release
288        5.0 to both the input and output. (It makes no difference on Unix-like
289        systems.) Later I was told that it is wrong for the input on Windows. I've
290        now abstracted the modes into two macros, to make it easier to fiddle with
291        them, and removed "b" from the input mode under Windows.
293    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
295    12. Added -help and --help to pcretest as an official way of being reminded
296        of the options.
298    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
299        and pcrecpp.cc because they annoy compilers at high warning levels.
301    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
303    15. Fixed an occurrence of == in configure.ac that should have been = (shell
304        scripts are not C programs :-) and which was not noticed because it works
305        on Linux.
307    16. pcretest is supposed to handle any length of pattern and data line (as one
308        line or as a continued sequence of lines) by extending its input buffer if
309        necessary. This feature was broken for very long pattern lines, leading to
310        a string of junk being passed to pcre_compile() if the pattern was longer
311        than about 50K.
313    17. I have done a major re-factoring of the way pcre_compile() computes the
314        amount of memory needed for a compiled pattern. Previously, there was code
315        that made a preliminary scan of the pattern in order to do this. That was
316        OK when PCRE was new, but as the facilities have expanded, it has become
317        harder and harder to keep it in step with the real compile phase, and there
318        have been a number of bugs (see for example, 4 above). I have now found a
319        cunning way of running the real compile function in a "fake" mode that
320        enables it to compute how much memory it would need, while actually only
321        ever using a few hundred bytes of working memory and without too many
322        tests of the mode. This should make future maintenance and development
323        easier. A side effect of this work is that the limit of 200 on the nesting
324        depth of parentheses has been removed (though this was never a serious
325        limitation, I suspect). However, there is a downside: pcre_compile() now
326        runs more slowly than before (30% or more, depending on the pattern). I
327        hope this isn't a big issue. There is no effect on runtime performance.
329    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
330        newline (only possible for the last line of a file) and it was a
331        pattern that set a locale (followed by /Lsomething), pcretest crashed.
333    19. Added additional timing features to pcretest. (1) The -tm option now times
334        matching only, not compiling. (2) Both -t and -tm can be followed, as a
335        separate command line item, by a number that specifies the number of
336        repeats to use when timing. The default is 50000; this gives better
337        precision, but takes uncomfortably long for very large patterns.
339    20. Extended pcre_study() to be more clever in cases where a branch of a
340        subpattern has no definite first character. For example, (a*|b*)[cd] would
341        previously give no result from pcre_study(). Now it recognizes that the
342        first character must be a, b, c, or d.
344    21. There was an incorrect error "recursive call could loop indefinitely" if
345        a subpattern (or the entire pattern) that was being tested for matching an
346        empty string contained only one non-empty item after a nested subpattern.
347        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
348        incorrectly, because the \d was being skipped in the check.
350    22. The pcretest program now has a new pattern option /B and a command line
351        option -b, which is equivalent to adding /B to every pattern. This causes
352        it to show the compiled bytecode, without the additional information that
353        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
354        is the same as /B/I).
356    23. A new optimization is now able automatically to treat some sequences such
357        as a*b as a*+b. More specifically, if something simple (such as a character
358        or a simple class like \d) has an unlimited quantifier, and is followed by
359        something that cannot possibly match the quantified thing, the quantifier
360        is automatically "possessified".
362    24. A recursive reference to a subpattern whose number was greater than 39
363        went wrong under certain circumstances in UTF-8 mode. This bug could also
364        have affected the operation of pcre_study().
366    25. Realized that a little bit of performance could be had by replacing
367        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
369    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
371    27. Possessive quantifiers such as a++ were previously implemented by turning
372        them into atomic groups such as ($>a+). Now they have their own opcodes,
373        which improves performance. This includes the automatically created ones
374        from 23 above.
376    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
377        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
378        the first matched character to be a colon. This applied both to named and
379        numbered groups.
381    29. The ucpinternal.h header file was missing its idempotency #ifdef.
383    30. I was sent a "project" file called libpcre.a.dev which I understand makes
384        building PCRE on Windows easier, so I have included it in the distribution.
386    31. There is now a check in pcretest against a ridiculously large number being
387        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
388        loop, the loop is abandoned.
390    32. Forward references to subpatterns in conditions such as (?(2)...) where
391        subpattern 2 is defined later cause pcre_compile() to search forwards in
392        the pattern for the relevant set of parentheses. This search went wrong
393        when there were unescaped parentheses in a character class, parentheses
394        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
396    33. "Subroutine" calls and backreferences were previously restricted to
397        referencing subpatterns earlier in the regex. This restriction has now
398        been removed.
400    34. Added a number of extra features that are going to be in Perl 5.10. On the
401        whole, these are just syntactic alternatives for features that PCRE had
402        previously implemented using the Python syntax or my own invention. The
403        other formats are all retained for compatibility.
405        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
406            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
407            also .NET compatible.
409        (b) A recursion or subroutine call to a named group can now be defined as
410            (?&name) as well as (?P>name).
412        (c) A backreference to a named group can now be defined as \k<name> or
413            \k'name' as well as (?P=name). The new forms, as well as being in Perl
414            5.10, are also .NET compatible.
416        (d) A conditional reference to a named group can now use the syntax
417            (?(<name>) or (?('name') as well as (?(name).
419        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
420            groups (named and numbered) that are never evaluated inline, but can be
421            called as "subroutines" from elsewhere. In effect, the DEFINE condition
422            is always false. There may be only one alternative in such a group.
424        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
425            as the simple (?(R). The condition is true only if the most recent
426            recursion is that of the given number or name. It does not search out
427            through the entire recursion stack.
429        (g) The escape \gN or \g{N} has been added, where N is a positive or
430            negative number, specifying an absolute or relative reference.
432    35. Tidied to get rid of some further signed/unsigned compiler warnings and
433        some "unreachable code" warnings.
435    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
436        things, this adds five new scripts.
438    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
439        There were also incompatibilities regarding the handling of \Q..\E inside
440        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
441        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
443    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
444        matches an empty string, and forcibly breaks the loop. There were bugs in
445        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
446        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
447        separate and independent bugs (that affected different cases) have been
448        fixed.
450    39. Refactored the code to abolish the use of different opcodes for small
451        capturing bracket numbers. This is a tidy that I avoided doing when I
452        removed the limit on the number of capturing brackets for 3.5 back in 2001.
453        The new approach is not only tidier, it makes it possible to reduce the
454        memory needed to fix the previous bug (38).
456    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
457        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
458        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
459        mode.
461    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
462        report.
464    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
465        copy construction and assignment in the C++ wrapper.
467    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
468        couple of bugs that could have given wrong results in the "--newline=crlf"
469        case.
471    44. Added a number of casts and did some reorganization of signed/unsigned int
472        variables following suggestions from Dair Grant. Also renamed the variable
473        "this" as "item" because it is a C++ keyword.
475    45. Arranged for dftables to add
477          #include "pcre_internal.h"
479        to pcre_chartables.c because without it, gcc 4.x may remove the array
480        definition from the final binary if PCRE is built into a static library and
481        dead code stripping is activated.
483    46. For an unanchored pattern, if a match attempt fails at the start of a
484        newline sequence, and the newline setting is CRLF or ANY, and the next two
485        characters are CRLF, advance by two characters instead of one.
488    Version 6.7 04-Jul-06
489    ---------------------
491     1. In order to handle tests when input lines are enormously long, pcretest has
492        been re-factored so that it automatically extends its buffers when
493        necessary. The code is crude, but this _is_ just a test program. The
494        default size has been increased from 32K to 50K.
496     2. The code in pcre_study() was using the value of the re argument before
497        testing it for NULL. (Of course, in any sensible call of the function, it
498        won't be NULL.)
500     3. The memmove() emulation function in pcre_internal.h, which is used on
501        systems that lack both memmove() and bcopy() - that is, hardly ever -
502        was missing a "static" storage class specifier.
504     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
505        containing an extended class (one that cannot be represented by a bitmap
506        because it contains high-valued characters or Unicode property items, e.g.
507        [\pZ]). Almost always one would set UTF-8 mode when processing such a
508        pattern, but PCRE should not loop if you do not (it no longer does).
509        [Detail: two cases were found: (a) a repeated subpattern containing an
510        extended class; (b) a recursive reference to a subpattern that followed a
511        previous extended class. It wasn't skipping over the extended class
512        correctly when UTF-8 mode was not set.]
514     5. A negated single-character class was not being recognized as fixed-length
515        in lookbehind assertions such as (?<=[^f]), leading to an incorrect
516        compile error "lookbehind assertion is not fixed length".
518     6. The RunPerlTest auxiliary script was showing an unexpected difference
519        between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
520        write a Perl script that can interpret lines of an input file either as
521        byte characters or as UTF-8, which is what "perltest" was being required to
522        do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
523        can't do is switch easily at run time between having the "use utf8;" pragma
524        or not. In the end, I fudged it by using the RunPerlTest script to insert
525        "use utf8;" explicitly for the UTF-8 tests.
527     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
528        the end of the subject string, contrary to the documentation and to what
529        Perl does. This was true of both matching functions. Now it matches only at
530        the start of the subject and immediately after *internal* newlines.
532     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
533        a pointer to an int instead of a pointer to an unsigned long int. This
534        caused problems on 64-bit systems.
536     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
537        instance of the 'standard' template library not being so standard".
539    10. There was no check on the number of named subpatterns nor the maximum
540        length of a subpattern name. The product of these values is used to compute
541        the size of the memory block for a compiled pattern. By supplying a very
542        long subpattern name and a large number of named subpatterns, the size
543        computation could be caused to overflow. This is now prevented by limiting
544        the length of names to 32 characters, and the number of named subpatterns
545        to 10,000.
547    11. Subpatterns that are repeated with specific counts have to be replicated in
548        the compiled pattern. The size of memory for this was computed from the
549        length of the subpattern and the repeat count. The latter is limited to
550        65535, but there was no limit on the former, meaning that integer overflow
551        could in principle occur. The compiled length of a repeated subpattern is
552        now limited to 30,000 bytes in order to prevent this.
554    12. Added the optional facility to have named substrings with the same name.
556    13. Added the ability to use a named substring as a condition, using the
557        Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
558        are numbers (not recommended). Forward references are permitted.
560    14. Added forward references in named backreferences (if you see what I mean).
562    15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
563        pattern could run off the end of the subject. For example, the pattern
564        "(?s)(.{1,5})"8 did this with the subject "ab".
566    16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
567        PCRE_CASELESS was set when matching characters that were quantified with ?
568        or *.
570    17. A character class other than a single negated character that had a minimum
571        but no maximum quantifier - for example [ab]{6,} - was not handled
572        correctly by pce_dfa_exec(). It would match only one character.
574    18. A valid (though odd) pattern that looked like a POSIX character
575        class but used an invalid character after [ (for example [[,abc,]]) caused
576        pcre_compile() to give the error "Failed: internal error: code overflow" or
577        in some cases to crash with a glibc free() error. This could even happen if
578        the pattern terminated after [[ but there just happened to be a sequence of
579        letters, a binary zero, and a closing ] in the memory that followed.
581    19. Perl's treatment of octal escapes in the range \400 to \777 has changed
582        over the years. Originally (before any Unicode support), just the bottom 8
583        bits were taken. Thus, for example, \500 really meant \100. Nowadays the
584        output from "man perlunicode" includes this:
586          The regular expression compiler produces polymorphic opcodes.  That
587          is, the pattern adapts to the data and automatically switches to
588          the Unicode character scheme when presented with Unicode data--or
589          instead uses a traditional byte scheme when presented with byte
590          data.
592        Sadly, a wide octal escape does not cause a switch, and in a string with
593        no other multibyte characters, these octal escapes are treated as before.
594        Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
595        /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
596        Unicode string.
598        I have not perpetrated such confusion in PCRE. Up till now, it took just
599        the bottom 8 bits, as in old Perl. I have now made octal escapes with
600        values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
601        translate to the appropriate multibyte character.
603    29. Applied some refactoring to reduce the number of warnings from Microsoft
604        and Borland compilers. This has included removing the fudge introduced
605        seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
606        a warning about an unused variable.
608    21. PCRE has not included VT (character 0x0b) in the set of whitespace
609        characters since release 4.0, because Perl (from release 5.004) does not.
610        [Or at least, is documented not to: some releases seem to be in conflict
611        with the documentation.] However, when a pattern was studied with
612        pcre_study() and all its branches started with \s, PCRE still included VT
613        as a possible starting character. Of course, this did no harm; it just
614        caused an unnecessary match attempt.
616    22. Removed a now-redundant internal flag bit that recorded the fact that case
617        dependency changed within the pattern. This was once needed for "required
618        byte" processing, but is no longer used. This recovers a now-scarce options
619        bit. Also moved the least significant internal flag bit to the most-
620        significant bit of the word, which was not previously used (hangover from
621        the days when it was an int rather than a uint) to free up another bit for
622        the future.
624    23. Added support for CRLF line endings as well as CR and LF. As well as the
625        default being selectable at build time, it can now be changed at runtime
626        via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
627        specify that it is scanning data with non-default line endings.
629    24. Changed the definition of CXXLINK to make it agree with the definition of
630        LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
632    25. Applied Ian Taylor's patches to avoid using another stack frame for tail
633        recursions. This makes a big different to stack usage for some patterns.
635    26. If a subpattern containing a named recursion or subroutine reference such
636        as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
637        the space required for the compiled pattern went wrong and gave too small a
638        value. Depending on the environment, this could lead to "Failed: internal
639        error: code overflow at offset 49" or "glibc detected double free or
640        corruption" errors.
642    27. Applied patches from Google (a) to support the new newline modes and (b) to
643        advance over multibyte UTF-8 characters in GlobalReplace.
645    28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
646        difference for some implementation of PCRE in some Windows version.
648    29. Added some extra testing facilities to pcretest:
650        \q<number>   in a data line sets the "match limit" value
651        \Q<number>   in a data line sets the "match recursion limt" value
652        -S <number>  sets the stack size, where <number> is in megabytes
654        The -S option isn't available for Windows.
657    Version 6.6 06-Feb-06
658    ---------------------
660     1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
661        in pcreposix.h. I have copied the definition from pcre.h.
663     2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
664        because pcre.h is no longer a built file.
666     3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
667        not normally included in the compiled code.
670    Version 6.5 01-Feb-06
671    ---------------------
673     1. When using the partial match feature with pcre_dfa_exec(), it was not
674        anchoring the second and subsequent partial matches at the new starting
675        point. This could lead to incorrect results. For example, with the pattern
676        /1234/, partially matching against "123" and then "a4" gave a match.
678     2. Changes to pcregrep:
680        (a) All non-match returns from pcre_exec() were being treated as failures
681            to match the line. Now, unless the error is PCRE_ERROR_NOMATCH, an
682            error message is output. Some extra information is given for the
683            PCRE_ERROR_MATCHLIMIT and PCRE_ERROR_RECURSIONLIMIT errors, which are
684            probably the only errors that are likely to be caused by users (by
685            specifying a regex that has nested indefinite repeats, for instance).
686            If there are more than 20 of these errors, pcregrep is abandoned.
688        (b) A binary zero was treated as data while matching, but terminated the
689            output line if it was written out. This has been fixed: binary zeroes
690            are now no different to any other data bytes.
692        (c) Whichever of the LC_ALL or LC_CTYPE environment variables is set is
693            used to set a locale for matching. The --locale=xxxx long option has
694            been added (no short equivalent) to specify a locale explicitly on the
695            pcregrep command, overriding the environment variables.
697        (d) When -B was used with -n, some line numbers in the output were one less
698            than they should have been.
700        (e) Added the -o (--only-matching) option.
702        (f) If -A or -C was used with -c (count only), some lines of context were
703            accidentally printed for the final match.
705        (g) Added the -H (--with-filename) option.
707        (h) The combination of options -rh failed to suppress file names for files
708            that were found from directory arguments.
710        (i) Added the -D (--devices) and -d (--directories) options.
712        (j) Added the -F (--fixed-strings) option.
714        (k) Allow "-" to be used as a file name for -f as well as for a data file.
716        (l) Added the --colo(u)r option.
718        (m) Added Jeffrey Friedl's -S testing option, but within #ifdefs so that it
719            is not present by default.
721     3. A nasty bug was discovered in the handling of recursive patterns, that is,
722        items such as (?R) or (?1), when the recursion could match a number of
723        alternatives. If it matched one of the alternatives, but subsequently,
724        outside the recursion, there was a failure, the code tried to back up into
725        the recursion. However, because of the way PCRE is implemented, this is not
726        possible, and the result was an incorrect result from the match.
728        In order to prevent this happening, the specification of recursion has
729        been changed so that all such subpatterns are automatically treated as
730        atomic groups. Thus, for example, (?R) is treated as if it were (?>(?R)).
732     4. I had overlooked the fact that, in some locales, there are characters for
733        which isalpha() is true but neither isupper() nor islower() are true. In
734        the fr_FR locale, for instance, the \xAA and \xBA characters (ordmasculine
735        and ordfeminine) are like this. This affected the treatment of \w and \W
736        when they appeared in character classes, but not when they appeared outside
737        a character class. The bit map for "word" characters is now created
738        separately from the results of isalnum() instead of just taking it from the
739        upper, lower, and digit maps. (Plus the underscore character, of course.)
741     5. The above bug also affected the handling of POSIX character classes such as
742        [[:alpha:]] and [[:alnum:]]. These do not have their own bit maps in PCRE's
743        permanent tables. Instead, the bit maps for such a class were previously
744        created as the appropriate unions of the upper, lower, and digit bitmaps.
745        Now they are created by subtraction from the [[:word:]] class, which has
746        its own bitmap.
748     6. The [[:blank:]] character class matches horizontal, but not vertical space.
749        It is created by subtracting the vertical space characters (\x09, \x0a,
750        \x0b, \x0c) from the [[:space:]] bitmap. Previously, however, the
751        subtraction was done in the overall bitmap for a character class, meaning
752        that a class such as [\x0c[:blank:]] was incorrect because \x0c would not
753        be recognized. This bug has been fixed.
755     7. Patches from the folks at Google:
757          (a) pcrecpp.cc: "to handle a corner case that may or may not happen in
758          real life, but is still worth protecting against".
760          (b) pcrecpp.cc: "corrects a bug when negative radixes are used with
761          regular expressions".
763          (c) pcre_scanner.cc: avoid use of std::count() because not all systems
764          have it.
766          (d) Split off pcrecpparg.h from pcrecpp.h and had the former built by
767          "configure" and the latter not, in order to fix a problem somebody had
768          with compiling the Arg class on HP-UX.
770          (e) Improve the error-handling of the C++ wrapper a little bit.
772          (f) New tests for checking recursion limiting.
774     8. The pcre_memmove() function, which is used only if the environment does not
775        have a standard memmove() function (and is therefore rarely compiled),
776        contained two bugs: (a) use of int instead of size_t, and (b) it was not
777        returning a result (though PCRE never actually uses the result).
779     9. In the POSIX regexec() interface, if nmatch is specified as a ridiculously
780        large number - greater than INT_MAX/(3*sizeof(int)) - REG_ESPACE is
781        returned instead of calling malloc() with an overflowing number that would
782        most likely cause subsequent chaos.
784    10. The debugging option of pcretest was not showing the NO_AUTO_CAPTURE flag.
786    11. The POSIX flag REG_NOSUB is now supported. When a pattern that was compiled
787        with this option is matched, the nmatch and pmatch options of regexec() are
788        ignored.
790    12. Added REG_UTF8 to the POSIX interface. This is not defined by POSIX, but is
791        provided in case anyone wants to the the POSIX interface with UTF-8
792        strings.
794    13. Added CXXLDFLAGS to the Makefile parameters to provide settings only on the
795        C++ linking (needed for some HP-UX environments).
797    14. Avoid compiler warnings in get_ucpname() when compiled without UCP support
798        (unused parameter) and in the pcre_printint() function (omitted "default"
799        switch label when the default is to do nothing).
801    15. Added some code to make it possible, when PCRE is compiled as a C++
802        library, to replace subject pointers for pcre_exec() with a smart pointer
803        class, thus making it possible to process discontinuous strings.
805    16. The two macros PCRE_EXPORT and PCRE_DATA_SCOPE are confusing, and perform
806        much the same function. They were added by different people who were trying
807        to make PCRE easy to compile on non-Unix systems. It has been suggested
808        that PCRE_EXPORT be abolished now that there is more automatic apparatus
809        for compiling on Windows systems. I have therefore replaced it with
810        PCRE_DATA_SCOPE. This is set automatically for Windows; if not set it
811        defaults to "extern" for C or "extern C" for C++, which works fine on
812        Unix-like systems. It is now possible to override the value of PCRE_DATA_
813        SCOPE with something explicit in config.h. In addition:
815        (a) pcreposix.h still had just "extern" instead of either of these macros;
816            I have replaced it with PCRE_DATA_SCOPE.
818        (b) Functions such as _pcre_xclass(), which are internal to the library,
819            but external in the C sense, all had PCRE_EXPORT in their definitions.
820            This is apparently wrong for the Windows case, so I have removed it.
821            (It makes no difference on Unix-like systems.)
823    17. Added a new limit, MATCH_LIMIT_RECURSION, which limits the depth of nesting
824        of recursive calls to match(). This is different to MATCH_LIMIT because
825        that limits the total number of calls to match(), not all of which increase
826        the depth of recursion. Limiting the recursion depth limits the amount of
827        stack (or heap if NO_RECURSE is set) that is used. The default can be set
828        when PCRE is compiled, and changed at run time. A patch from Google adds
829        this functionality to the C++ interface.
831    18. Changes to the handling of Unicode character properties:
833        (a) Updated the table to Unicode 4.1.0.
835        (b) Recognize characters that are not in the table as "Cn" (undefined).
837        (c) I revised the way the table is implemented to a much improved format
838            which includes recognition of ranges. It now supports the ranges that
839            are defined in UnicodeData.txt, and it also amalgamates other
840            characters into ranges. This has reduced the number of entries in the
841            table from around 16,000 to around 3,000, thus reducing its size
842            considerably. I realized I did not need to use a tree structure after
843            all - a binary chop search is just as efficient. Having reduced the
844            number of entries, I extended their size from 6 bytes to 8 bytes to
845            allow for more data.
847        (d) Added support for Unicode script names via properties such as \p{Han}.
849    19. In UTF-8 mode, a backslash followed by a non-Ascii character was not
850        matching that character.
852    20. When matching a repeated Unicode property with a minimum greater than zero,
853        (for example \pL{2,}), PCRE could look past the end of the subject if it
854        reached it while seeking the minimum number of characters. This could
855        happen only if some of the characters were more than one byte long, because
856        there is a check for at least the minimum number of bytes.
858    21. Refactored the implementation of \p and \P so as to be more general, to
859        allow for more different types of property in future. This has changed the
860        compiled form incompatibly. Anybody with saved compiled patterns that use
861        \p or \P will have to recompile them.
863    22. Added "Any" and "L&" to the supported property types.
865    23. Recognize \x{...} as a code point specifier, even when not in UTF-8 mode,
866        but give a compile time error if the value is greater than 0xff.
868    24. The man pages for pcrepartial, pcreprecompile, and pcre_compile2 were
869        accidentally not being installed or uninstalled.
871    25. The pcre.h file was built from pcre.h.in, but the only changes that were
872        made were to insert the current release number. This seemed silly, because
873        it made things harder for people building PCRE on systems that don't run
874        "configure". I have turned pcre.h into a distributed file, no longer built
875        by "configure", with the version identification directly included. There is
876        no longer a pcre.h.in file.
878        However, this change necessitated a change to the pcre-config script as
879        well. It is built from pcre-config.in, and one of the substitutions was the
880        release number. I have updated configure.ac so that ./configure now finds
881        the release number by grepping pcre.h.
883    26. Added the ability to run the tests under valgrind.
886    Version 6.4 05-Sep-05
887    ---------------------
889     1. Change 6.0/10/(l) to pcregrep introduced a bug that caused separator lines
890        "--" to be printed when multiple files were scanned, even when none of the
891        -A, -B, or -C options were used. This is not compatible with Gnu grep, so I
892        consider it to be a bug, and have restored the previous behaviour.
894     2. A couple of code tidies to get rid of compiler warnings.
896     3. The pcretest program used to cheat by referring to symbols in the library
897        whose names begin with _pcre_. These are internal symbols that are not
898        really supposed to be visible externally, and in some environments it is
899        possible to suppress them. The cheating is now confined to including
900        certain files from the library's source, which is a bit cleaner.
902     4. Renamed pcre.in as pcre.h.in to go with pcrecpp.h.in; it also makes the
903        file's purpose clearer.
905     5. Reorganized pcre_ucp_findchar().
908  Version 6.3 15-Aug-05  Version 6.3 15-Aug-05
909  ---------------------  ---------------------

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