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Mon Mar 12 15:10:25 2007 UTC (8 years, 1 month ago) by ph10
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Documentation spring clean, and expansion of maint/README.

1 nigel 3 ChangeLog for PCRE
2     ------------------
4 ph10 122 Version 7.1 12-Mar-07
5 ph10 98 ---------------------
7 ph10 111 1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
8 ph10 122 that is more "standard", making use of automake and other Autotools. There
9 ph10 99 is some re-arrangement of the files and adjustment of comments consequent
10     on this.
11 ph10 111
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 ph10 100 alternative.
18 ph10 111
19 ph10 100 3. I had an email from Eric Raymond about problems translating some of PCRE's
20 ph10 111 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 ph10 113 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.
27 ph10 111
28 ph10 100 4. Updated comments in configure.ac that get placed in config.h.in and also
29 ph10 111 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 !compile.txt,
36 ph10 101 !linklib.txt, and pcregexp.pas.
37 ph10 111
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 ph10 102 copy. The trailing space was an accident, so I've just removed it.
41 ph10 111
42 ph10 104 7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
43 ph10 111 that is needed.
45 ph10 105 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 ph10 111 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 ph10 105 re-created.
51 ph10 111
52     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
53 ph10 107 pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
54 ph10 111 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 ph10 107 some applications.
57 ph10 111
58 ph10 110 Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
59 ph10 111 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 ph10 118 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.
73 ph10 108
74 ph10 111 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".
80 ph10 115
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.
97 ph10 116
98     13. Some tidying changes to the testing mechanism:
99 ph10 98
100 ph10 116 (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 ph10 122 of link size. (Test 2 will be tidied up later.)
115 ph10 118
116 ph10 119 14. If erroroffset was passed as NULL to pcre_compile, it provoked a
117 ph10 122 segmentation fault instead of returning the appropriate error message.
118 ph10 119
119 ph10 111
120 nigel 93 Version 7.0 19-Dec-06
121     ---------------------
123     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
124     moving to gcc 4.1.1.
126     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
127     sys/time.h, which is documented as needed for this function. It doesn't
128     seem to matter on Linux, but it showed up on some releases of OS X.
130     3. It seems that there are systems where bytes whose values are greater than
131     127 match isprint() in the "C" locale. The "C" locale should be the
132     default when a C program starts up. In most systems, only ASCII printing
133     characters match isprint(). This difference caused the output from pcretest
134     to vary, making some of the tests fail. I have changed pcretest so that:
136     (a) When it is outputting text in the compiled version of a pattern, bytes
137     other than 32-126 are always shown as hex escapes.
139     (b) When it is outputting text that is a matched part of a subject string,
140     it does the same, unless a different locale has been set for the match
141     (using the /L modifier). In this case, it uses isprint() to decide.
143     4. Fixed a major bug that caused incorrect computation of the amount of memory
144     required for a compiled pattern when options that changed within the
145     pattern affected the logic of the preliminary scan that determines the
146     length. The relevant options are -x, and -i in UTF-8 mode. The result was
147     that the computed length was too small. The symptoms of this bug were
148     either the PCRE error "internal error: code overflow" from pcre_compile(),
149     or a glibc crash with a message such as "pcretest: free(): invalid next
150     size (fast)". Examples of patterns that provoked this bug (shown in
151     pcretest format) are:
153     /(?-x: )/x
154     /(?x)(?-x: \s*#\s*)/
155     /((?i)[\x{c0}])/8
156     /(?i:[\x{c0}])/8
158     HOWEVER: Change 17 below makes this fix obsolete as the memory computation
159     is now done differently.
161     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
162     wrapper classes; (b) implement a new function in the C++ scanner that is
163     more efficient than the old way of doing things because it avoids levels of
164     recursion in the regex matching; (c) add a paragraph to the documentation
165     for the FullMatch() function.
167     6. The escape sequence \n was being treated as whatever was defined as
168     "newline". Not only was this contrary to the documentation, which states
169     that \n is character 10 (hex 0A), but it also went horribly wrong when
170     "newline" was defined as CRLF. This has been fixed.
172     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
173     was being set to -1 for the "end of line" case (supposedly a value that no
174     character can have). Though this value is never used (the check for end of
175     line is "zero bytes in current character"), it caused compiler complaints.
176     I've changed it to 0xffffffff.
178     8. In pcre_version.c, the version string was being built by a sequence of
179     C macros that, in the event of PCRE_PRERELEASE being defined as an empty
180     string (as it is for production releases) called a macro with an empty
181     argument. The C standard says the result of this is undefined. The gcc
182     compiler treats it as an empty string (which was what was wanted) but it is
183     reported that Visual C gives an error. The source has been hacked around to
184     avoid this problem.
186     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
187     builds of pcretest, and changed the call to _setmode() to use _O_BINARY
188     instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
189     of them did).
191     10. Originally, pcretest opened its input and output without "b"; then I was
192     told that "b" was needed in some environments, so it was added for release
193     5.0 to both the input and output. (It makes no difference on Unix-like
194     systems.) Later I was told that it is wrong for the input on Windows. I've
195     now abstracted the modes into two macros, to make it easier to fiddle with
196     them, and removed "b" from the input mode under Windows.
198     11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
200     12. Added -help and --help to pcretest as an official way of being reminded
201     of the options.
203     13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
204     and pcrecpp.cc because they annoy compilers at high warning levels.
206     14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
208     15. Fixed an occurrence of == in configure.ac that should have been = (shell
209     scripts are not C programs :-) and which was not noticed because it works
210     on Linux.
212     16. pcretest is supposed to handle any length of pattern and data line (as one
213     line or as a continued sequence of lines) by extending its input buffer if
214     necessary. This feature was broken for very long pattern lines, leading to
215     a string of junk being passed to pcre_compile() if the pattern was longer
216     than about 50K.
218     17. I have done a major re-factoring of the way pcre_compile() computes the
219     amount of memory needed for a compiled pattern. Previously, there was code
220     that made a preliminary scan of the pattern in order to do this. That was
221     OK when PCRE was new, but as the facilities have expanded, it has become
222     harder and harder to keep it in step with the real compile phase, and there
223     have been a number of bugs (see for example, 4 above). I have now found a
224     cunning way of running the real compile function in a "fake" mode that
225     enables it to compute how much memory it would need, while actually only
226     ever using a few hundred bytes of working memory and without too many
227     tests of the mode. This should make future maintenance and development
228     easier. A side effect of this work is that the limit of 200 on the nesting
229     depth of parentheses has been removed (though this was never a serious
230     limitation, I suspect). However, there is a downside: pcre_compile() now
231     runs more slowly than before (30% or more, depending on the pattern). I
232     hope this isn't a big issue. There is no effect on runtime performance.
234     18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
235     newline (only possible for the last line of a file) and it was a
236     pattern that set a locale (followed by /Lsomething), pcretest crashed.
238     19. Added additional timing features to pcretest. (1) The -tm option now times
239     matching only, not compiling. (2) Both -t and -tm can be followed, as a
240     separate command line item, by a number that specifies the number of
241     repeats to use when timing. The default is 50000; this gives better
242     precision, but takes uncomfortably long for very large patterns.
244     20. Extended pcre_study() to be more clever in cases where a branch of a
245     subpattern has no definite first character. For example, (a*|b*)[cd] would
246     previously give no result from pcre_study(). Now it recognizes that the
247     first character must be a, b, c, or d.
249     21. There was an incorrect error "recursive call could loop indefinitely" if
250     a subpattern (or the entire pattern) that was being tested for matching an
251     empty string contained only one non-empty item after a nested subpattern.
252     For example, the pattern (?>\x{100}*)\d(?R) provoked this error
253     incorrectly, because the \d was being skipped in the check.
255     22. The pcretest program now has a new pattern option /B and a command line
256     option -b, which is equivalent to adding /B to every pattern. This causes
257     it to show the compiled bytecode, without the additional information that
258     -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
259     is the same as /B/I).
261     23. A new optimization is now able automatically to treat some sequences such
262     as a*b as a*+b. More specifically, if something simple (such as a character
263     or a simple class like \d) has an unlimited quantifier, and is followed by
264     something that cannot possibly match the quantified thing, the quantifier
265     is automatically "possessified".
267     24. A recursive reference to a subpattern whose number was greater than 39
268     went wrong under certain circumstances in UTF-8 mode. This bug could also
269     have affected the operation of pcre_study().
271     25. Realized that a little bit of performance could be had by replacing
272     (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
274     26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
276     27. Possessive quantifiers such as a++ were previously implemented by turning
277     them into atomic groups such as ($>a+). Now they have their own opcodes,
278     which improves performance. This includes the automatically created ones
279     from 23 above.
281     28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
282     lookahead was broken if it was not anchored. PCRE was mistakenly expecting
283     the first matched character to be a colon. This applied both to named and
284     numbered groups.
286     29. The ucpinternal.h header file was missing its idempotency #ifdef.
288     30. I was sent a "project" file called libpcre.a.dev which I understand makes
289     building PCRE on Windows easier, so I have included it in the distribution.
291     31. There is now a check in pcretest against a ridiculously large number being
292     returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
293     loop, the loop is abandoned.
295     32. Forward references to subpatterns in conditions such as (?(2)...) where
296     subpattern 2 is defined later cause pcre_compile() to search forwards in
297     the pattern for the relevant set of parentheses. This search went wrong
298     when there were unescaped parentheses in a character class, parentheses
299     escaped with \Q...\E, or parentheses in a #-comment in /x mode.
301     33. "Subroutine" calls and backreferences were previously restricted to
302     referencing subpatterns earlier in the regex. This restriction has now
303     been removed.
305     34. Added a number of extra features that are going to be in Perl 5.10. On the
306     whole, these are just syntactic alternatives for features that PCRE had
307     previously implemented using the Python syntax or my own invention. The
308     other formats are all retained for compatibility.
310     (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
311     as (?P<name>...). The new forms, as well as being in Perl 5.10, are
312     also .NET compatible.
314     (b) A recursion or subroutine call to a named group can now be defined as
315     (?&name) as well as (?P>name).
317     (c) A backreference to a named group can now be defined as \k<name> or
318     \k'name' as well as (?P=name). The new forms, as well as being in Perl
319     5.10, are also .NET compatible.
321     (d) A conditional reference to a named group can now use the syntax
322     (?(<name>) or (?('name') as well as (?(name).
324     (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
325     groups (named and numbered) that are never evaluated inline, but can be
326     called as "subroutines" from elsewhere. In effect, the DEFINE condition
327     is always false. There may be only one alternative in such a group.
329     (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
330     as the simple (?(R). The condition is true only if the most recent
331     recursion is that of the given number or name. It does not search out
332     through the entire recursion stack.
334     (g) The escape \gN or \g{N} has been added, where N is a positive or
335     negative number, specifying an absolute or relative reference.
337     35. Tidied to get rid of some further signed/unsigned compiler warnings and
338     some "unreachable code" warnings.
340     36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
341     things, this adds five new scripts.
343     37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
344     There were also incompatibilities regarding the handling of \Q..\E inside
345     character classes, for example with patterns like [\Qa\E-\Qz\E] where the
346     hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
348     38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
349     matches an empty string, and forcibly breaks the loop. There were bugs in
350     this code in non-simple cases. For a pattern such as ^(a()*)* matched
351     against aaaa the result was just "a" rather than "aaaa", for example. Two
352     separate and independent bugs (that affected different cases) have been
353     fixed.
355     39. Refactored the code to abolish the use of different opcodes for small
356     capturing bracket numbers. This is a tidy that I avoided doing when I
357     removed the limit on the number of capturing brackets for 3.5 back in 2001.
358     The new approach is not only tidier, it makes it possible to reduce the
359     memory needed to fix the previous bug (38).
361     40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
362     sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
363     processing dot, circumflex, or dollar metacharacters, or #-comments in /x
364     mode.
366     41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
367     report.
369     42. Applied patch, originally from Ari Pollak, modified by Google, to allow
370     copy construction and assignment in the C++ wrapper.
372     43. Updated pcregrep to support "--newline=any". In the process, I fixed a
373     couple of bugs that could have given wrong results in the "--newline=crlf"
374     case.
376     44. Added a number of casts and did some reorganization of signed/unsigned int
377     variables following suggestions from Dair Grant. Also renamed the variable
378     "this" as "item" because it is a C++ keyword.
380     45. Arranged for dftables to add
382     #include "pcre_internal.h"
384     to pcre_chartables.c because without it, gcc 4.x may remove the array
385     definition from the final binary if PCRE is built into a static library and
386     dead code stripping is activated.
388     46. For an unanchored pattern, if a match attempt fails at the start of a
389     newline sequence, and the newline setting is CRLF or ANY, and the next two
390     characters are CRLF, advance by two characters instead of one.
393 nigel 91 Version 6.7 04-Jul-06
394     ---------------------
396     1. In order to handle tests when input lines are enormously long, pcretest has
397     been re-factored so that it automatically extends its buffers when
398     necessary. The code is crude, but this _is_ just a test program. The
399     default size has been increased from 32K to 50K.
401     2. The code in pcre_study() was using the value of the re argument before
402     testing it for NULL. (Of course, in any sensible call of the function, it
403     won't be NULL.)
405     3. The memmove() emulation function in pcre_internal.h, which is used on
406     systems that lack both memmove() and bcopy() - that is, hardly ever -
407     was missing a "static" storage class specifier.
409     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
410     containing an extended class (one that cannot be represented by a bitmap
411     because it contains high-valued characters or Unicode property items, e.g.
412     [\pZ]). Almost always one would set UTF-8 mode when processing such a
413     pattern, but PCRE should not loop if you do not (it no longer does).
414     [Detail: two cases were found: (a) a repeated subpattern containing an
415     extended class; (b) a recursive reference to a subpattern that followed a
416     previous extended class. It wasn't skipping over the extended class
417     correctly when UTF-8 mode was not set.]
419     5. A negated single-character class was not being recognized as fixed-length
420     in lookbehind assertions such as (?<=[^f]), leading to an incorrect
421     compile error "lookbehind assertion is not fixed length".
423     6. The RunPerlTest auxiliary script was showing an unexpected difference
424     between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
425     write a Perl script that can interpret lines of an input file either as
426     byte characters or as UTF-8, which is what "perltest" was being required to
427     do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
428     can't do is switch easily at run time between having the "use utf8;" pragma
429     or not. In the end, I fudged it by using the RunPerlTest script to insert
430     "use utf8;" explicitly for the UTF-8 tests.
432     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
433     the end of the subject string, contrary to the documentation and to what
434     Perl does. This was true of both matching functions. Now it matches only at
435     the start of the subject and immediately after *internal* newlines.
437     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
438     a pointer to an int instead of a pointer to an unsigned long int. This
439     caused problems on 64-bit systems.
441     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
442     instance of the 'standard' template library not being so standard".
444     10. There was no check on the number of named subpatterns nor the maximum
445     length of a subpattern name. The product of these values is used to compute
446     the size of the memory block for a compiled pattern. By supplying a very
447     long subpattern name and a large number of named subpatterns, the size
448     computation could be caused to overflow. This is now prevented by limiting
449     the length of names to 32 characters, and the number of named subpatterns
450     to 10,000.
452     11. Subpatterns that are repeated with specific counts have to be replicated in
453     the compiled pattern. The size of memory for this was computed from the
454     length of the subpattern and the repeat count. The latter is limited to
455     65535, but there was no limit on the former, meaning that integer overflow
456     could in principle occur. The compiled length of a repeated subpattern is
457     now limited to 30,000 bytes in order to prevent this.
459     12. Added the optional facility to have named substrings with the same name.
461     13. Added the ability to use a named substring as a condition, using the
462     Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
463     are numbers (not recommended). Forward references are permitted.
465     14. Added forward references in named backreferences (if you see what I mean).
467     15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
468     pattern could run off the end of the subject. For example, the pattern
469     "(?s)(.{1,5})"8 did this with the subject "ab".
471     16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
472     PCRE_CASELESS was set when matching characters that were quantified with ?
473     or *.
475     17. A character class other than a single negated character that had a minimum
476     but no maximum quantifier - for example [ab]{6,} - was not handled
477     correctly by pce_dfa_exec(). It would match only one character.
479     18. A valid (though odd) pattern that looked like a POSIX character
480     class but used an invalid character after [ (for example [[,abc,]]) caused
481     pcre_compile() to give the error "Failed: internal error: code overflow" or
482     in some cases to crash with a glibc free() error. This could even happen if
483     the pattern terminated after [[ but there just happened to be a sequence of
484     letters, a binary zero, and a closing ] in the memory that followed.
486     19. Perl's treatment of octal escapes in the range \400 to \777 has changed
487     over the years. Originally (before any Unicode support), just the bottom 8
488     bits were taken. Thus, for example, \500 really meant \100. Nowadays the
489     output from "man perlunicode" includes this:
491     The regular expression compiler produces polymorphic opcodes. That
492     is, the pattern adapts to the data and automatically switches to
493     the Unicode character scheme when presented with Unicode data--or
494     instead uses a traditional byte scheme when presented with byte
495     data.
497     Sadly, a wide octal escape does not cause a switch, and in a string with
498     no other multibyte characters, these octal escapes are treated as before.
499     Thus, in Perl, the pattern /\500/ actually matches \100 but the pattern
500     /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
501     Unicode string.
503     I have not perpetrated such confusion in PCRE. Up till now, it took just
504     the bottom 8 bits, as in old Perl. I have now made octal escapes with
505     values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
506     translate to the appropriate multibyte character.
508     29. Applied some refactoring to reduce the number of warnings from Microsoft
509     and Borland compilers. This has included removing the fudge introduced
510     seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
511     a warning about an unused variable.
513     21. PCRE has not included VT (character 0x0b) in the set of whitespace
514     characters since release 4.0, because Perl (from release 5.004) does not.
515     [Or at least, is documented not to: some releases seem to be in conflict
516     with the documentation.] However, when a pattern was studied with
517     pcre_study() and all its branches started with \s, PCRE still included VT
518     as a possible starting character. Of course, this did no harm; it just
519     caused an unnecessary match attempt.
521     22. Removed a now-redundant internal flag bit that recorded the fact that case
522     dependency changed within the pattern. This was once needed for "required
523     byte" processing, but is no longer used. This recovers a now-scarce options
524     bit. Also moved the least significant internal flag bit to the most-
525     significant bit of the word, which was not previously used (hangover from
526     the days when it was an int rather than a uint) to free up another bit for
527     the future.
529     23. Added support for CRLF line endings as well as CR and LF. As well as the
530     default being selectable at build time, it can now be changed at runtime
531     via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
532     specify that it is scanning data with non-default line endings.
534     24. Changed the definition of CXXLINK to make it agree with the definition of
535     LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
537     25. Applied Ian Taylor's patches to avoid using another stack frame for tail
538     recursions. This makes a big different to stack usage for some patterns.
540     26. If a subpattern containing a named recursion or subroutine reference such
541     as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
542     the space required for the compiled pattern went wrong and gave too small a
543     value. Depending on the environment, this could lead to "Failed: internal
544     error: code overflow at offset 49" or "glibc detected double free or
545     corruption" errors.
547     27. Applied patches from Google (a) to support the new newline modes and (b) to
548     advance over multibyte UTF-8 characters in GlobalReplace.
550     28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
551     difference for some implementation of PCRE in some Windows version.
553     29. Added some extra testing facilities to pcretest:
555     \q<number> in a data line sets the "match limit" value
556     \Q<number> in a data line sets the "match recursion limt" value
557     -S <number> sets the stack size, where <number> is in megabytes
559     The -S option isn't available for Windows.
562 nigel 89 Version 6.6 06-Feb-06
563     ---------------------
565     1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
566     in pcreposix.h. I have copied the definition from pcre.h.
568     2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
569     because pcre.h is no longer a built file.
571     3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
572     not normally included in the compiled code.
575 nigel 87 Version 6.5 01-Feb-06
576     ---------------------
578     1. When using the partial match feature with pcre_dfa_exec(), it was not
579     anchoring the second and subsequent partial matches at the new starting
580     point. This could lead to incorrect results. For example, with the pattern
581     /1234/, partially matching against "123" and then "a4" gave a match.
583     2. Changes to pcregrep:
585     (a) All non-match returns from pcre_exec() were being treated as failures
586     to match the line. Now, unless the error is PCRE_ERROR_NOMATCH, an
587     error message is output. Some extra information is given for the
589     probably the only errors that are likely to be caused by users (by
590     specifying a regex that has nested indefinite repeats, for instance).
591     If there are more than 20 of these errors, pcregrep is abandoned.
593     (b) A binary zero was treated as data while matching, but terminated the
594     output line if it was written out. This has been fixed: binary zeroes
595     are now no different to any other data bytes.
597     (c) Whichever of the LC_ALL or LC_CTYPE environment variables is set is
598     used to set a locale for matching. The --locale=xxxx long option has
599     been added (no short equivalent) to specify a locale explicitly on the
600     pcregrep command, overriding the environment variables.
602     (d) When -B was used with -n, some line numbers in the output were one less
603     than they should have been.
605     (e) Added the -o (--only-matching) option.
607     (f) If -A or -C was used with -c (count only), some lines of context were
608     accidentally printed for the final match.
610     (g) Added the -H (--with-filename) option.
612     (h) The combination of options -rh failed to suppress file names for files
613     that were found from directory arguments.
615     (i) Added the -D (--devices) and -d (--directories) options.
617     (j) Added the -F (--fixed-strings) option.
619     (k) Allow "-" to be used as a file name for -f as well as for a data file.
621     (l) Added the --colo(u)r option.
623     (m) Added Jeffrey Friedl's -S testing option, but within #ifdefs so that it
624     is not present by default.
626     3. A nasty bug was discovered in the handling of recursive patterns, that is,
627     items such as (?R) or (?1), when the recursion could match a number of
628     alternatives. If it matched one of the alternatives, but subsequently,
629     outside the recursion, there was a failure, the code tried to back up into
630     the recursion. However, because of the way PCRE is implemented, this is not
631     possible, and the result was an incorrect result from the match.
633     In order to prevent this happening, the specification of recursion has
634     been changed so that all such subpatterns are automatically treated as
635     atomic groups. Thus, for example, (?R) is treated as if it were (?>(?R)).
637     4. I had overlooked the fact that, in some locales, there are characters for
638     which isalpha() is true but neither isupper() nor islower() are true. In
639     the fr_FR locale, for instance, the \xAA and \xBA characters (ordmasculine
640     and ordfeminine) are like this. This affected the treatment of \w and \W
641     when they appeared in character classes, but not when they appeared outside
642     a character class. The bit map for "word" characters is now created
643     separately from the results of isalnum() instead of just taking it from the
644     upper, lower, and digit maps. (Plus the underscore character, of course.)
646     5. The above bug also affected the handling of POSIX character classes such as
647     [[:alpha:]] and [[:alnum:]]. These do not have their own bit maps in PCRE's
648     permanent tables. Instead, the bit maps for such a class were previously
649     created as the appropriate unions of the upper, lower, and digit bitmaps.
650     Now they are created by subtraction from the [[:word:]] class, which has
651     its own bitmap.
653     6. The [[:blank:]] character class matches horizontal, but not vertical space.
654     It is created by subtracting the vertical space characters (\x09, \x0a,
655     \x0b, \x0c) from the [[:space:]] bitmap. Previously, however, the
656     subtraction was done in the overall bitmap for a character class, meaning
657     that a class such as [\x0c[:blank:]] was incorrect because \x0c would not
658     be recognized. This bug has been fixed.
660     7. Patches from the folks at Google:
662     (a) pcrecpp.cc: "to handle a corner case that may or may not happen in
663     real life, but is still worth protecting against".
665     (b) pcrecpp.cc: "corrects a bug when negative radixes are used with
666     regular expressions".
668     (c) pcre_scanner.cc: avoid use of std::count() because not all systems
669     have it.
671     (d) Split off pcrecpparg.h from pcrecpp.h and had the former built by
672     "configure" and the latter not, in order to fix a problem somebody had
673     with compiling the Arg class on HP-UX.
675     (e) Improve the error-handling of the C++ wrapper a little bit.
677     (f) New tests for checking recursion limiting.
679     8. The pcre_memmove() function, which is used only if the environment does not
680     have a standard memmove() function (and is therefore rarely compiled),
681     contained two bugs: (a) use of int instead of size_t, and (b) it was not
682     returning a result (though PCRE never actually uses the result).
684     9. In the POSIX regexec() interface, if nmatch is specified as a ridiculously
685     large number - greater than INT_MAX/(3*sizeof(int)) - REG_ESPACE is
686     returned instead of calling malloc() with an overflowing number that would
687     most likely cause subsequent chaos.
689     10. The debugging option of pcretest was not showing the NO_AUTO_CAPTURE flag.
691     11. The POSIX flag REG_NOSUB is now supported. When a pattern that was compiled
692     with this option is matched, the nmatch and pmatch options of regexec() are
693     ignored.
695     12. Added REG_UTF8 to the POSIX interface. This is not defined by POSIX, but is
696     provided in case anyone wants to the the POSIX interface with UTF-8
697     strings.
699     13. Added CXXLDFLAGS to the Makefile parameters to provide settings only on the
700     C++ linking (needed for some HP-UX environments).
702     14. Avoid compiler warnings in get_ucpname() when compiled without UCP support
703     (unused parameter) and in the pcre_printint() function (omitted "default"
704     switch label when the default is to do nothing).
706     15. Added some code to make it possible, when PCRE is compiled as a C++
707     library, to replace subject pointers for pcre_exec() with a smart pointer
708     class, thus making it possible to process discontinuous strings.
710     16. The two macros PCRE_EXPORT and PCRE_DATA_SCOPE are confusing, and perform
711     much the same function. They were added by different people who were trying
712     to make PCRE easy to compile on non-Unix systems. It has been suggested
713     that PCRE_EXPORT be abolished now that there is more automatic apparatus
714     for compiling on Windows systems. I have therefore replaced it with
715     PCRE_DATA_SCOPE. This is set automatically for Windows; if not set it
716     defaults to "extern" for C or "extern C" for C++, which works fine on
717     Unix-like systems. It is now possible to override the value of PCRE_DATA_
718     SCOPE with something explicit in config.h. In addition:
720     (a) pcreposix.h still had just "extern" instead of either of these macros;
721     I have replaced it with PCRE_DATA_SCOPE.
723     (b) Functions such as _pcre_xclass(), which are internal to the library,
724     but external in the C sense, all had PCRE_EXPORT in their definitions.
725     This is apparently wrong for the Windows case, so I have removed it.
726     (It makes no difference on Unix-like systems.)
728     17. Added a new limit, MATCH_LIMIT_RECURSION, which limits the depth of nesting
729     of recursive calls to match(). This is different to MATCH_LIMIT because
730     that limits the total number of calls to match(), not all of which increase
731     the depth of recursion. Limiting the recursion depth limits the amount of
732     stack (or heap if NO_RECURSE is set) that is used. The default can be set
733     when PCRE is compiled, and changed at run time. A patch from Google adds
734     this functionality to the C++ interface.
736     18. Changes to the handling of Unicode character properties:
738     (a) Updated the table to Unicode 4.1.0.
740     (b) Recognize characters that are not in the table as "Cn" (undefined).
742     (c) I revised the way the table is implemented to a much improved format
743     which includes recognition of ranges. It now supports the ranges that
744     are defined in UnicodeData.txt, and it also amalgamates other
745     characters into ranges. This has reduced the number of entries in the
746     table from around 16,000 to around 3,000, thus reducing its size
747     considerably. I realized I did not need to use a tree structure after
748     all - a binary chop search is just as efficient. Having reduced the
749     number of entries, I extended their size from 6 bytes to 8 bytes to
750     allow for more data.
752     (d) Added support for Unicode script names via properties such as \p{Han}.
754     19. In UTF-8 mode, a backslash followed by a non-Ascii character was not
755     matching that character.
757     20. When matching a repeated Unicode property with a minimum greater than zero,
758     (for example \pL{2,}), PCRE could look past the end of the subject if it
759     reached it while seeking the minimum number of characters. This could
760     happen only if some of the characters were more than one byte long, because
761     there is a check for at least the minimum number of bytes.
763     21. Refactored the implementation of \p and \P so as to be more general, to
764     allow for more different types of property in future. This has changed the
765     compiled form incompatibly. Anybody with saved compiled patterns that use
766     \p or \P will have to recompile them.
768     22. Added "Any" and "L&" to the supported property types.
770     23. Recognize \x{...} as a code point specifier, even when not in UTF-8 mode,
771     but give a compile time error if the value is greater than 0xff.
773     24. The man pages for pcrepartial, pcreprecompile, and pcre_compile2 were
774     accidentally not being installed or uninstalled.
776     25. The pcre.h file was built from pcre.h.in, but the only changes that were
777     made were to insert the current release number. This seemed silly, because
778     it made things harder for people building PCRE on systems that don't run
779     "configure". I have turned pcre.h into a distributed file, no longer built
780     by "configure", with the version identification directly included. There is
781     no longer a pcre.h.in file.
783     However, this change necessitated a change to the pcre-config script as
784     well. It is built from pcre-config.in, and one of the substitutions was the
785     release number. I have updated configure.ac so that ./configure now finds
786     the release number by grepping pcre.h.
788     26. Added the ability to run the tests under valgrind.
791 nigel 85 Version 6.4 05-Sep-05
792     ---------------------
794     1. Change 6.0/10/(l) to pcregrep introduced a bug that caused separator lines
795     "--" to be printed when multiple files were scanned, even when none of the
796     -A, -B, or -C options were used. This is not compatible with Gnu grep, so I
797     consider it to be a bug, and have restored the previous behaviour.
799     2. A couple of code tidies to get rid of compiler warnings.
801     3. The pcretest program used to cheat by referring to symbols in the library
802     whose names begin with _pcre_. These are internal symbols that are not
803     really supposed to be visible externally, and in some environments it is
804     possible to suppress them. The cheating is now confined to including
805     certain files from the library's source, which is a bit cleaner.
807     4. Renamed pcre.in as pcre.h.in to go with pcrecpp.h.in; it also makes the
808     file's purpose clearer.
810     5. Reorganized pcre_ucp_findchar().
813 nigel 83 Version 6.3 15-Aug-05
814     ---------------------
816     1. The file libpcre.pc.in did not have general read permission in the tarball.
818     2. There were some problems when building without C++ support:
820     (a) If C++ support was not built, "make install" and "make test" still
821     tried to test it.
823     (b) There were problems when the value of CXX was explicitly set. Some
824     changes have been made to try to fix these, and ...
826     (c) --disable-cpp can now be used to explicitly disable C++ support.
828     (d) The use of @CPP_OBJ@ directly caused a blank line preceded by a
829     backslash in a target when C++ was disabled. This confuses some
830     versions of "make", apparently. Using an intermediate variable solves
831     this. (Same for CPP_LOBJ.)
833     3. $(LINK_FOR_BUILD) now includes $(CFLAGS_FOR_BUILD) and $(LINK)
834     (non-Windows) now includes $(CFLAGS) because these flags are sometimes
835     necessary on certain architectures.
837     4. Added a setting of -export-symbols-regex to the link command to remove
838     those symbols that are exported in the C sense, but actually are local
839     within the library, and not documented. Their names all begin with
840     "_pcre_". This is not a perfect job, because (a) we have to except some
841     symbols that pcretest ("illegally") uses, and (b) the facility isn't always
842     available (and never for static libraries). I have made a note to try to
843     find a way round (a) in the future.
846 nigel 81 Version 6.2 01-Aug-05
847     ---------------------
849     1. There was no test for integer overflow of quantifier values. A construction
850     such as {1111111111111111} would give undefined results. What is worse, if
851     a minimum quantifier for a parenthesized subpattern overflowed and became
852     negative, the calculation of the memory size went wrong. This could have
853     led to memory overwriting.
855     2. Building PCRE using VPATH was broken. Hopefully it is now fixed.
857     3. Added "b" to the 2nd argument of fopen() in dftables.c, for non-Unix-like
858     operating environments where this matters.
860     4. Applied Giuseppe Maxia's patch to add additional features for controlling
861     PCRE options from within the C++ wrapper.
863     5. Named capturing subpatterns were not being correctly counted when a pattern
864     was compiled. This caused two problems: (a) If there were more than 100
865     such subpatterns, the calculation of the memory needed for the whole
866     compiled pattern went wrong, leading to an overflow error. (b) Numerical
867     back references of the form \12, where the number was greater than 9, were
868     not recognized as back references, even though there were sufficient
869     previous subpatterns.
871     6. Two minor patches to pcrecpp.cc in order to allow it to compile on older
872     versions of gcc, e.g. 2.95.4.
875 nigel 79 Version 6.1 21-Jun-05
876     ---------------------
878     1. There was one reference to the variable "posix" in pcretest.c that was not
879     surrounded by "#if !defined NOPOSIX".
881     2. Make it possible to compile pcretest without DFA support, UTF8 support, or
882     the cross-check on the old pcre_info() function, for the benefit of the
883     cut-down version of PCRE that is currently imported into Exim.
885     3. A (silly) pattern starting with (?i)(?-i) caused an internal space
886     allocation error. I've done the easy fix, which wastes 2 bytes for sensible
887     patterns that start (?i) but I don't think that matters. The use of (?i) is
888     just an example; this all applies to the other options as well.
890     4. Since libtool seems to echo the compile commands it is issuing, the output
891     from "make" can be reduced a bit by putting "@" in front of each libtool
892     compile command.
894     5. Patch from the folks at Google for configure.in to be a bit more thorough
895     in checking for a suitable C++ installation before trying to compile the
896     C++ stuff. This should fix a reported problem when a compiler was present,
897     but no suitable headers.
899     6. The man pages all had just "PCRE" as their title. I have changed them to
900     be the relevant file name. I have also arranged that these names are
901     retained in the file doc/pcre.txt, which is a concatenation in text format
902     of all the man pages except the little individual ones for each function.
904     7. The NON-UNIX-USE file had not been updated for the different set of source
905     files that come with release 6. I also added a few comments about the C++
906     wrapper.
909 nigel 77 Version 6.0 07-Jun-05
910     ---------------------
912     1. Some minor internal re-organization to help with my DFA experiments.
914     2. Some missing #ifdef SUPPORT_UCP conditionals in pcretest and printint that
915     didn't matter for the library itself when fully configured, but did matter
916     when compiling without UCP support, or within Exim, where the ucp files are
917     not imported.
919     3. Refactoring of the library code to split up the various functions into
920     different source modules. The addition of the new DFA matching code (see
921     below) to a single monolithic source would have made it really too
922     unwieldy, quite apart from causing all the code to be include in a
923     statically linked application, when only some functions are used. This is
924     relevant even without the DFA addition now that patterns can be compiled in
925     one application and matched in another.
927     The downside of splitting up is that there have to be some external
928     functions and data tables that are used internally in different modules of
929     the library but which are not part of the API. These have all had their
930     names changed to start with "_pcre_" so that they are unlikely to clash
931     with other external names.
933     4. Added an alternate matching function, pcre_dfa_exec(), which matches using
934     a different (DFA) algorithm. Although it is slower than the original
935     function, it does have some advantages for certain types of matching
936     problem.
938     5. Upgrades to pcretest in order to test the features of pcre_dfa_exec(),
939     including restarting after a partial match.
941     6. A patch for pcregrep that defines INVALID_FILE_ATTRIBUTES if it is not
942     defined when compiling for Windows was sent to me. I have put it into the
943     code, though I have no means of testing or verifying it.
945     7. Added the pcre_refcount() auxiliary function.
947     8. Added the PCRE_FIRSTLINE option. This constrains an unanchored pattern to
948     match before or at the first newline in the subject string. In pcretest,
949     the /f option on a pattern can be used to set this.
951     9. A repeated \w when used in UTF-8 mode with characters greater than 256
952     would behave wrongly. This has been present in PCRE since release 4.0.
954     10. A number of changes to the pcregrep command:
956     (a) Refactored how -x works; insert ^(...)$ instead of setting
957     PCRE_ANCHORED and checking the length, in preparation for adding
958     something similar for -w.
960     (b) Added the -w (match as a word) option.
962     (c) Refactored the way lines are read and buffered so as to have more
963     than one at a time available.
965     (d) Implemented a pcregrep test script.
967     (e) Added the -M (multiline match) option. This allows patterns to match
968     over several lines of the subject. The buffering ensures that at least
969     8K, or the rest of the document (whichever is the shorter) is available
970     for matching (and similarly the previous 8K for lookbehind assertions).
972     (f) Changed the --help output so that it now says
974     -w, --word-regex(p)
976     instead of two lines, one with "regex" and the other with "regexp"
977     because that confused at least one person since the short forms are the
978     same. (This required a bit of code, as the output is generated
979     automatically from a table. It wasn't just a text change.)
981     (g) -- can be used to terminate pcregrep options if the next thing isn't an
982     option but starts with a hyphen. Could be a pattern or a path name
983     starting with a hyphen, for instance.
985     (h) "-" can be given as a file name to represent stdin.
987     (i) When file names are being printed, "(standard input)" is used for
988     the standard input, for compatibility with GNU grep. Previously
989     "<stdin>" was used.
991     (j) The option --label=xxx can be used to supply a name to be used for
992     stdin when file names are being printed. There is no short form.
994     (k) Re-factored the options decoding logic because we are going to add
995     two more options that take data. Such options can now be given in four
996     different ways, e.g. "-fname", "-f name", "--file=name", "--file name".
998     (l) Added the -A, -B, and -C options for requesting that lines of context
999     around matches be printed.
1001     (m) Added the -L option to print the names of files that do not contain
1002     any matching lines, that is, the complement of -l.
1004     (n) The return code is 2 if any file cannot be opened, but pcregrep does
1005     continue to scan other files.
1007     (o) The -s option was incorrectly implemented. For compatibility with other
1008     greps, it now suppresses the error message for a non-existent or non-
1009     accessible file (but not the return code). There is a new option called
1010     -q that suppresses the output of matching lines, which was what -s was
1011     previously doing.
1013     (p) Added --include and --exclude options to specify files for inclusion
1014     and exclusion when recursing.
1016     11. The Makefile was not using the Autoconf-supported LDFLAGS macro properly.
1017     Hopefully, it now does.
1019     12. Missing cast in pcre_study().
1021     13. Added an "uninstall" target to the makefile.
1023     14. Replaced "extern" in the function prototypes in Makefile.in with
1024     "PCRE_DATA_SCOPE", which defaults to 'extern' or 'extern "C"' in the Unix
1025     world, but is set differently for Windows.
1027     15. Added a second compiling function called pcre_compile2(). The only
1028     difference is that it has an extra argument, which is a pointer to an
1029     integer error code. When there is a compile-time failure, this is set
1030     non-zero, in addition to the error test pointer being set to point to an
1031     error message. The new argument may be NULL if no error number is required
1032     (but then you may as well call pcre_compile(), which is now just a
1033     wrapper). This facility is provided because some applications need a
1034     numeric error indication, but it has also enabled me to tidy up the way
1035     compile-time errors are handled in the POSIX wrapper.
1037     16. Added VPATH=.libs to the makefile; this should help when building with one
1038     prefix path and installing with another. (Or so I'm told by someone who
1039     knows more about this stuff than I do.)
1041     17. Added a new option, REG_DOTALL, to the POSIX function regcomp(). This
1042     passes PCRE_DOTALL to the pcre_compile() function, making the "." character
1043     match everything, including newlines. This is not POSIX-compatible, but
1044     somebody wanted the feature. From pcretest it can be activated by using
1045     both the P and the s flags.
1047     18. AC_PROG_LIBTOOL appeared twice in Makefile.in. Removed one.
1049     19. libpcre.pc was being incorrectly installed as executable.
1051     20. A couple of places in pcretest check for end-of-line by looking for '\n';
1052     it now also looks for '\r' so that it will work unmodified on Windows.
1054     21. Added Google's contributed C++ wrapper to the distribution.
1056     22. Added some untidy missing memory free() calls in pcretest, to keep
1057     Electric Fence happy when testing.
1061 nigel 75 Version 5.0 13-Sep-04
1062     ---------------------
1064     1. Internal change: literal characters are no longer packed up into items
1065     containing multiple characters in a single byte-string. Each character
1066     is now matched using a separate opcode. However, there may be more than one
1067     byte in the character in UTF-8 mode.
1069     2. The pcre_callout_block structure has two new fields: pattern_position and
1070     next_item_length. These contain the offset in the pattern to the next match
1071     item, and its length, respectively.
1073     3. The PCRE_AUTO_CALLOUT option for pcre_compile() requests the automatic
1074     insertion of callouts before each pattern item. Added the /C option to
1075     pcretest to make use of this.
1077     4. On the advice of a Windows user, the lines
1079     #if defined(_WIN32) || defined(WIN32)
1080     _setmode( _fileno( stdout ), 0x8000 );
1081     #endif /* defined(_WIN32) || defined(WIN32) */
1083     have been added to the source of pcretest. This apparently does useful
1084     magic in relation to line terminators.
1086     5. Changed "r" and "w" in the calls to fopen() in pcretest to "rb" and "wb"
1087     for the benefit of those environments where the "b" makes a difference.
1089     6. The icc compiler has the same options as gcc, but "configure" doesn't seem
1090     to know about it. I have put a hack into configure.in that adds in code
1091     to set GCC=yes if CC=icc. This seems to end up at a point in the
1092     generated configure script that is early enough to affect the setting of
1093     compiler options, which is what is needed, but I have no means of testing
1094     whether it really works. (The user who reported this had patched the
1095     generated configure script, which of course I cannot do.)
1097     LATER: After change 22 below (new libtool files), the configure script
1098     seems to know about icc (and also ecc). Therefore, I have commented out
1099     this hack in configure.in.
1101     7. Added support for pkg-config (2 patches were sent in).
1103     8. Negated POSIX character classes that used a combination of internal tables
1104     were completely broken. These were [[:^alpha:]], [[:^alnum:]], and
1105     [[:^ascii]]. Typically, they would match almost any characters. The other
1106     POSIX classes were not broken in this way.
1108     9. Matching the pattern "\b.*?" against "ab cd", starting at offset 1, failed
1109     to find the match, as PCRE was deluded into thinking that the match had to
1110     start at the start point or following a newline. The same bug applied to
1111     patterns with negative forward assertions or any backward assertions
1112     preceding ".*" at the start, unless the pattern required a fixed first
1113     character. This was a failing pattern: "(?!.bcd).*". The bug is now fixed.
1115     10. In UTF-8 mode, when moving forwards in the subject after a failed match
1116     starting at the last subject character, bytes beyond the end of the subject
1117     string were read.
1119     11. Renamed the variable "class" as "classbits" to make life easier for C++
1120     users. (Previously there was a macro definition, but it apparently wasn't
1121     enough.)
1123     12. Added the new field "tables" to the extra data so that tables can be passed
1124     in at exec time, or the internal tables can be re-selected. This allows
1125     a compiled regex to be saved and re-used at a later time by a different
1126     program that might have everything at different addresses.
1128     13. Modified the pcre-config script so that, when run on Solaris, it shows a
1129     -R library as well as a -L library.
1131     14. The debugging options of pcretest (-d on the command line or D on a
1132     pattern) showed incorrect output for anything following an extended class
1133     that contained multibyte characters and which was followed by a quantifier.
1135     15. Added optional support for general category Unicode character properties
1136     via the \p, \P, and \X escapes. Unicode property support implies UTF-8
1137     support. It adds about 90K to the size of the library. The meanings of the
1138     inbuilt class escapes such as \d and \s have NOT been changed.
1140     16. Updated pcredemo.c to include calls to free() to release the memory for the
1141     compiled pattern.
1143     17. The generated file chartables.c was being created in the source directory
1144     instead of in the building directory. This caused the build to fail if the
1145     source directory was different from the building directory, and was
1146     read-only.
1148     18. Added some sample Win commands from Mark Tetrode into the NON-UNIX-USE
1149     file. No doubt somebody will tell me if they don't make sense... Also added
1150     Dan Mooney's comments about building on OpenVMS.
1152     19. Added support for partial matching via the PCRE_PARTIAL option for
1153     pcre_exec() and the \P data escape in pcretest.
1155     20. Extended pcretest with 3 new pattern features:
1157     (i) A pattern option of the form ">rest-of-line" causes pcretest to
1158     write the compiled pattern to the file whose name is "rest-of-line".
1159     This is a straight binary dump of the data, with the saved pointer to
1160     the character tables forced to be NULL. The study data, if any, is
1161     written too. After writing, pcretest reads a new pattern.
1163     (ii) If, instead of a pattern, "<rest-of-line" is given, pcretest reads a
1164     compiled pattern from the given file. There must not be any
1165     occurrences of "<" in the file name (pretty unlikely); if there are,
1166     pcretest will instead treat the initial "<" as a pattern delimiter.
1167     After reading in the pattern, pcretest goes on to read data lines as
1168     usual.
1170     (iii) The F pattern option causes pcretest to flip the bytes in the 32-bit
1171     and 16-bit fields in a compiled pattern, to simulate a pattern that
1172     was compiled on a host of opposite endianness.
1174     21. The pcre-exec() function can now cope with patterns that were compiled on
1175     hosts of opposite endianness, with this restriction:
1177     As for any compiled expression that is saved and used later, the tables
1178     pointer field cannot be preserved; the extra_data field in the arguments
1179     to pcre_exec() should be used to pass in a tables address if a value
1180     other than the default internal tables were used at compile time.
1182     22. Calling pcre_exec() with a negative value of the "ovecsize" parameter is
1183     now diagnosed as an error. Previously, most of the time, a negative number
1184     would have been treated as zero, but if in addition "ovector" was passed as
1185     NULL, a crash could occur.
1187     23. Updated the files ltmain.sh, config.sub, config.guess, and aclocal.m4 with
1188     new versions from the libtool 1.5 distribution (the last one is a copy of
1189     a file called libtool.m4). This seems to have fixed the need to patch
1190     "configure" to support Darwin 1.3 (which I used to do). However, I still
1191     had to patch ltmain.sh to ensure that ${SED} is set (it isn't on my
1192     workstation).
1194     24. Changed the PCRE licence to be the more standard "BSD" licence.
1197 nigel 73 Version 4.5 01-Dec-03
1198     ---------------------
1200     1. There has been some re-arrangement of the code for the match() function so
1201     that it can be compiled in a version that does not call itself recursively.
1202     Instead, it keeps those local variables that need separate instances for
1203     each "recursion" in a frame on the heap, and gets/frees frames whenever it
1204     needs to "recurse". Keeping track of where control must go is done by means
1205     of setjmp/longjmp. The whole thing is implemented by a set of macros that
1206     hide most of the details from the main code, and operates only if
1207     NO_RECURSE is defined while compiling pcre.c. If PCRE is built using the
1208     "configure" mechanism, "--disable-stack-for-recursion" turns on this way of
1209     operating.
1211     To make it easier for callers to provide specially tailored get/free
1212     functions for this usage, two new functions, pcre_stack_malloc, and
1213     pcre_stack_free, are used. They are always called in strict stacking order,
1214     and the size of block requested is always the same.
1216     The PCRE_CONFIG_STACKRECURSE info parameter can be used to find out whether
1217     PCRE has been compiled to use the stack or the heap for recursion. The
1218     -C option of pcretest uses this to show which version is compiled.
1220     A new data escape \S, is added to pcretest; it causes the amounts of store
1221     obtained and freed by both kinds of malloc/free at match time to be added
1222     to the output.
1224     2. Changed the locale test to use "fr_FR" instead of "fr" because that's
1225     what's available on my current Linux desktop machine.
1227     3. When matching a UTF-8 string, the test for a valid string at the start has
1228     been extended. If start_offset is not zero, PCRE now checks that it points
1229     to a byte that is the start of a UTF-8 character. If not, it returns
1230     PCRE_ERROR_BADUTF8_OFFSET (-11). Note: the whole string is still checked;
1231     this is necessary because there may be backward assertions in the pattern.
1232     When matching the same subject several times, it may save resources to use
1233     PCRE_NO_UTF8_CHECK on all but the first call if the string is long.
1235     4. The code for checking the validity of UTF-8 strings has been tightened so
1236     that it rejects (a) strings containing 0xfe or 0xff bytes and (b) strings
1237     containing "overlong sequences".
1239     5. Fixed a bug (appearing twice) that I could not find any way of exploiting!
1240     I had written "if ((digitab[*p++] && chtab_digit) == 0)" where the "&&"
1241     should have been "&", but it just so happened that all the cases this let
1242     through by mistake were picked up later in the function.
1244     6. I had used a variable called "isblank" - this is a C99 function, causing
1245     some compilers to warn. To avoid this, I renamed it (as "blankclass").
1247     7. Cosmetic: (a) only output another newline at the end of pcretest if it is
1248     prompting; (b) run "./pcretest /dev/null" at the start of the test script
1249     so the version is shown; (c) stop "make test" echoing "./RunTest".
1251     8. Added patches from David Burgess to enable PCRE to run on EBCDIC systems.
1253     9. The prototype for memmove() for systems that don't have it was using
1254     size_t, but the inclusion of the header that defines size_t was later. I've
1255     moved the #includes for the C headers earlier to avoid this.
1257     10. Added some adjustments to the code to make it easier to compiler on certain
1258     special systems:
1260     (a) Some "const" qualifiers were missing.
1261     (b) Added the macro EXPORT before all exported functions; by default this
1262     is defined to be empty.
1263     (c) Changed the dftables auxiliary program (that builds chartables.c) so
1264     that it reads its output file name as an argument instead of writing
1265     to the standard output and assuming this can be redirected.
1267     11. In UTF-8 mode, if a recursive reference (e.g. (?1)) followed a character
1268     class containing characters with values greater than 255, PCRE compilation
1269     went into a loop.
1271     12. A recursive reference to a subpattern that was within another subpattern
1272     that had a minimum quantifier of zero caused PCRE to crash. For example,
1273     (x(y(?2))z)? provoked this bug with a subject that got as far as the
1274     recursion. If the recursively-called subpattern itself had a zero repeat,
1275     that was OK.
1277     13. In pcretest, the buffer for reading a data line was set at 30K, but the
1278     buffer into which it was copied (for escape processing) was still set at
1279     1024, so long lines caused crashes.
1281     14. A pattern such as /[ab]{1,3}+/ failed to compile, giving the error
1282     "internal error: code overflow...". This applied to any character class
1283     that was followed by a possessive quantifier.
1285     15. Modified the Makefile to add libpcre.la as a prerequisite for
1286     libpcreposix.la because I was told this is needed for a parallel build to
1287     work.
1289     16. If a pattern that contained .* following optional items at the start was
1290     studied, the wrong optimizing data was generated, leading to matching
1291     errors. For example, studying /[ab]*.*c/ concluded, erroneously, that any
1292     matching string must start with a or b or c. The correct conclusion for
1293     this pattern is that a match can start with any character.
1296 nigel 71 Version 4.4 13-Aug-03
1297     ---------------------
1299     1. In UTF-8 mode, a character class containing characters with values between
1300     127 and 255 was not handled correctly if the compiled pattern was studied.
1301     In fixing this, I have also improved the studying algorithm for such
1302     classes (slightly).
1304     2. Three internal functions had redundant arguments passed to them. Removal
1305     might give a very teeny performance improvement.
1307     3. Documentation bug: the value of the capture_top field in a callout is *one
1308     more than* the number of the hightest numbered captured substring.
1310     4. The Makefile linked pcretest and pcregrep with -lpcre, which could result
1311     in incorrectly linking with a previously installed version. They now link
1312     explicitly with libpcre.la.
1314     5. configure.in no longer needs to recognize Cygwin specially.
1316     6. A problem in pcre.in for Windows platforms is fixed.
1318     7. If a pattern was successfully studied, and the -d (or /D) flag was given to
1319     pcretest, it used to include the size of the study block as part of its
1320     output. Unfortunately, the structure contains a field that has a different
1321     size on different hardware architectures. This meant that the tests that
1322     showed this size failed. As the block is currently always of a fixed size,
1323     this information isn't actually particularly useful in pcretest output, so
1324     I have just removed it.
1326     8. Three pre-processor statements accidentally did not start in column 1.
1327     Sadly, there are *still* compilers around that complain, even though
1328     standard C has not required this for well over a decade. Sigh.
1330     9. In pcretest, the code for checking callouts passed small integers in the
1331     callout_data field, which is a void * field. However, some picky compilers
1332     complained about the casts involved for this on 64-bit systems. Now
1333     pcretest passes the address of the small integer instead, which should get
1334     rid of the warnings.
1336     10. By default, when in UTF-8 mode, PCRE now checks for valid UTF-8 strings at
1337     both compile and run time, and gives an error if an invalid UTF-8 sequence
1338     is found. There is a option for disabling this check in cases where the
1339     string is known to be correct and/or the maximum performance is wanted.
1341     11. In response to a bug report, I changed one line in Makefile.in from
1343     -Wl,--out-implib,.libs/lib@WIN_PREFIX@pcreposix.dll.a \
1344     to
1345     -Wl,--out-implib,.libs/@WIN_PREFIX@libpcreposix.dll.a \
1347     to look similar to other lines, but I have no way of telling whether this
1348     is the right thing to do, as I do not use Windows. No doubt I'll get told
1349     if it's wrong...
1352 nigel 69 Version 4.3 21-May-03
1353     ---------------------
1355     1. Two instances of @WIN_PREFIX@ omitted from the Windows targets in the
1356     Makefile.
1358     2. Some refactoring to improve the quality of the code:
1360     (i) The utf8_table... variables are now declared "const".
1362     (ii) The code for \cx, which used the "case flipping" table to upper case
1363     lower case letters, now just substracts 32. This is ASCII-specific,
1364     but the whole concept of \cx is ASCII-specific, so it seems
1365     reasonable.
1367     (iii) PCRE was using its character types table to recognize decimal and
1368     hexadecimal digits in the pattern. This is silly, because it handles
1369     only 0-9, a-f, and A-F, but the character types table is locale-
1370     specific, which means strange things might happen. A private
1371     table is now used for this - though it costs 256 bytes, a table is
1372     much faster than multiple explicit tests. Of course, the standard
1373     character types table is still used for matching digits in subject
1374     strings against \d.
1376     (iv) Strictly, the identifier ESC_t is reserved by POSIX (all identifiers
1377     ending in _t are). So I've renamed it as ESC_tee.
1379     3. The first argument for regexec() in the POSIX wrapper should have been
1380     defined as "const".
1382     4. Changed pcretest to use malloc() for its buffers so that they can be
1383     Electric Fenced for debugging.
1385     5. There were several places in the code where, in UTF-8 mode, PCRE would try
1386     to read one or more bytes before the start of the subject string. Often this
1387     had no effect on PCRE's behaviour, but in some circumstances it could
1388     provoke a segmentation fault.
1390     6. A lookbehind at the start of a pattern in UTF-8 mode could also cause PCRE
1391     to try to read one or more bytes before the start of the subject string.
1393     7. A lookbehind in a pattern matched in non-UTF-8 mode on a PCRE compiled with
1394     UTF-8 support could misbehave in various ways if the subject string
1395     contained bytes with the 0x80 bit set and the 0x40 bit unset in a lookbehind
1396     area. (PCRE was not checking for the UTF-8 mode flag, and trying to move
1397     back over UTF-8 characters.)
1400 nigel 67 Version 4.2 14-Apr-03
1401     ---------------------
1403     1. Typo "#if SUPPORT_UTF8" instead of "#ifdef SUPPORT_UTF8" fixed.
1405     2. Changes to the building process, supplied by Ronald Landheer-Cieslak
1406     [ON_WINDOWS]: new variable, "#" on non-Windows platforms
1407     [NOT_ON_WINDOWS]: new variable, "#" on Windows platforms
1408     [WIN_PREFIX]: new variable, "cyg" for Cygwin
1409     * Makefile.in: use autoconf substitution for OBJEXT, EXEEXT, BUILD_OBJEXT
1410     and BUILD_EXEEXT
1411     Note: automatic setting of the BUILD variables is not yet working
1412     set CPPFLAGS and BUILD_CPPFLAGS (but don't use yet) - should be used at
1413     compile-time but not at link-time
1414     [LINK]: use for linking executables only
1415     make different versions for Windows and non-Windows
1416     [LINKLIB]: new variable, copy of UNIX-style LINK, used for linking
1417     libraries
1418     [LINK_FOR_BUILD]: new variable
1419     [OBJEXT]: use throughout
1420     [EXEEXT]: use throughout
1421     <winshared>: new target
1422     <wininstall>: new target
1423     <dftables.o>: use native compiler
1424     <dftables>: use native linker
1425     <install>: handle Windows platform correctly
1426     <clean>: ditto
1427     <check>: ditto
1428     copy DLL to top builddir before testing
1430     As part of these changes, -no-undefined was removed again. This was reported
1431     to give trouble on HP-UX 11.0, so getting rid of it seems like a good idea
1432     in any case.
1434     3. Some tidies to get rid of compiler warnings:
1436     . In the match_data structure, match_limit was an unsigned long int, whereas
1437     match_call_count was an int. I've made them both unsigned long ints.
1439     . In pcretest the fact that a const uschar * doesn't automatically cast to
1440     a void * provoked a warning.
1442     . Turning on some more compiler warnings threw up some "shadow" variables
1443     and a few more missing casts.
1445     4. If PCRE was complied with UTF-8 support, but called without the PCRE_UTF8
1446     option, a class that contained a single character with a value between 128
1447     and 255 (e.g. /[\xFF]/) caused PCRE to crash.
1449     5. If PCRE was compiled with UTF-8 support, but called without the PCRE_UTF8
1450     option, a class that contained several characters, but with at least one
1451     whose value was between 128 and 255 caused PCRE to crash.
1454 nigel 65 Version 4.1 12-Mar-03
1455     ---------------------
1456 nigel 63
1457 nigel 65 1. Compiling with gcc -pedantic found a couple of places where casts were
1458     needed, and a string in dftables.c that was longer than standard compilers are
1459     required to support.
1461     2. Compiling with Sun's compiler found a few more places where the code could
1462     be tidied up in order to avoid warnings.
1464     3. The variables for cross-compiling were called HOST_CC and HOST_CFLAGS; the
1465     first of these names is deprecated in the latest Autoconf in favour of the name
1466     CC_FOR_BUILD, because "host" is typically used to mean the system on which the
1467     compiled code will be run. I can't find a reference for HOST_CFLAGS, but by
1468     analogy I have changed it to CFLAGS_FOR_BUILD.
1470     4. Added -no-undefined to the linking command in the Makefile, because this is
1471     apparently helpful for Windows. To make it work, also added "-L. -lpcre" to the
1472     linking step for the pcreposix library.
1474     5. PCRE was failing to diagnose the case of two named groups with the same
1475     name.
1477     6. A problem with one of PCRE's optimizations was discovered. PCRE remembers a
1478     literal character that is needed in the subject for a match, and scans along to
1479     ensure that it is present before embarking on the full matching process. This
1480     saves time in cases of nested unlimited repeats that are never going to match.
1481     Problem: the scan can take a lot of time if the subject is very long (e.g.
1482     megabytes), thus penalizing straightforward matches. It is now done only if the
1483     amount of subject to be scanned is less than 1000 bytes.
1485     7. A lesser problem with the same optimization is that it was recording the
1486     first character of an anchored pattern as "needed", thus provoking a search
1487     right along the subject, even when the first match of the pattern was going to
1488     fail. The "needed" character is now not set for anchored patterns, unless it
1489     follows something in the pattern that is of non-fixed length. Thus, it still
1490     fulfils its original purpose of finding quick non-matches in cases of nested
1491     unlimited repeats, but isn't used for simple anchored patterns such as /^abc/.
1494     Version 4.0 17-Feb-03
1495     ---------------------
1497 nigel 63 1. If a comment in an extended regex that started immediately after a meta-item
1498     extended to the end of string, PCRE compiled incorrect data. This could lead to
1499     all kinds of weird effects. Example: /#/ was bad; /()#/ was bad; /a#/ was not.
1501     2. Moved to autoconf 2.53 and libtool 1.4.2.
1503     3. Perl 5.8 no longer needs "use utf8" for doing UTF-8 things. Consequently,
1504     the special perltest8 script is no longer needed - all the tests can be run
1505     from a single perltest script.
1507     4. From 5.004, Perl has not included the VT character (0x0b) in the set defined
1508     by \s. It has now been removed in PCRE. This means it isn't recognized as
1509     whitespace in /x regexes too, which is the same as Perl. Note that the POSIX
1510     class [:space:] *does* include VT, thereby creating a mess.
1512     5. Added the class [:blank:] (a GNU extension from Perl 5.8) to match only
1513     space and tab.
1515     6. Perl 5.005 was a long time ago. It's time to amalgamate the tests that use
1516     its new features into the main test script, reducing the number of scripts.
1518     7. Perl 5.8 has changed the meaning of patterns like /a(?i)b/. Earlier versions
1519     were backward compatible, and made the (?i) apply to the whole pattern, as if
1520     /i were given. Now it behaves more logically, and applies the option setting
1521     only to what follows. PCRE has been changed to follow suit. However, if it
1522     finds options settings right at the start of the pattern, it extracts them into
1523     the global options, as before. Thus, they show up in the info data.
1525     8. Added support for the \Q...\E escape sequence. Characters in between are
1526     treated as literals. This is slightly different from Perl in that $ and @ are
1527     also handled as literals inside the quotes. In Perl, they will cause variable
1528     interpolation. Note the following examples:
1530     Pattern PCRE matches Perl matches
1532     \Qabc$xyz\E abc$xyz abc followed by the contents of $xyz
1533     \Qabc\$xyz\E abc\$xyz abc\$xyz
1534     \Qabc\E\$\Qxyz\E abc$xyz abc$xyz
1536     For compatibility with Perl, \Q...\E sequences are recognized inside character
1537     classes as well as outside them.
1539     9. Re-organized 3 code statements in pcretest to avoid "overflow in
1540     floating-point constant arithmetic" warnings from a Microsoft compiler. Added a
1541     (size_t) cast to one statement in pcretest and one in pcreposix to avoid
1542     signed/unsigned warnings.
1544     10. SunOS4 doesn't have strtoul(). This was used only for unpicking the -o
1545     option for pcretest, so I've replaced it by a simple function that does just
1546     that job.
1548     11. pcregrep was ending with code 0 instead of 2 for the commands "pcregrep" or
1549     "pcregrep -".
1551     12. Added "possessive quantifiers" ?+, *+, ++, and {,}+ which come from Sun's
1552     Java package. This provides some syntactic sugar for simple cases of what my
1553     documentation calls "once-only subpatterns". A pattern such as x*+ is the same
1554     as (?>x*). In other words, if what is inside (?>...) is just a single repeated
1555     item, you can use this simplified notation. Note that only makes sense with
1556     greedy quantifiers. Consequently, the use of the possessive quantifier forces
1557     greediness, whatever the setting of the PCRE_UNGREEDY option.
1559     13. A change of greediness default within a pattern was not taking effect at
1560     the current level for patterns like /(b+(?U)a+)/. It did apply to parenthesized
1561     subpatterns that followed. Patterns like /b+(?U)a+/ worked because the option
1562     was abstracted outside.
1564     14. PCRE now supports the \G assertion. It is true when the current matching
1565     position is at the start point of the match. This differs from \A when the
1566     starting offset is non-zero. Used with the /g option of pcretest (or similar
1567     code), it works in the same way as it does for Perl's /g option. If all
1568     alternatives of a regex begin with \G, the expression is anchored to the start
1569     match position, and the "anchored" flag is set in the compiled expression.
1571     15. Some bugs concerning the handling of certain option changes within patterns
1572     have been fixed. These applied to options other than (?ims). For example,
1573     "a(?x: b c )d" did not match "XabcdY" but did match "Xa b c dY". It should have
1574     been the other way round. Some of this was related to change 7 above.
1576     16. PCRE now gives errors for /[.x.]/ and /[=x=]/ as unsupported POSIX
1577     features, as Perl does. Previously, PCRE gave the warnings only for /[[.x.]]/
1578     and /[[=x=]]/. PCRE now also gives an error for /[:name:]/ because it supports
1579     POSIX classes only within a class (e.g. /[[:alpha:]]/).
1581     17. Added support for Perl's \C escape. This matches one byte, even in UTF8
1582     mode. Unlike ".", it always matches newline, whatever the setting of
1583     PCRE_DOTALL. However, PCRE does not permit \C to appear in lookbehind
1584     assertions. Perl allows it, but it doesn't (in general) work because it can't
1585     calculate the length of the lookbehind. At least, that's the case for Perl
1586     5.8.0 - I've been told they are going to document that it doesn't work in
1587     future.
1589     18. Added an error diagnosis for escapes that PCRE does not support: these are
1590     \L, \l, \N, \P, \p, \U, \u, and \X.
1592     19. Although correctly diagnosing a missing ']' in a character class, PCRE was
1593     reading past the end of the pattern in cases such as /[abcd/.
1595     20. PCRE was getting more memory than necessary for patterns with classes that
1596     contained both POSIX named classes and other characters, e.g. /[[:space:]abc/.
1598     21. Added some code, conditional on #ifdef VPCOMPAT, to make life easier for
1599     compiling PCRE for use with Virtual Pascal.
1601     22. Small fix to the Makefile to make it work properly if the build is done
1602     outside the source tree.
1604     23. Added a new extension: a condition to go with recursion. If a conditional
1605     subpattern starts with (?(R) the "true" branch is used if recursion has
1606     happened, whereas the "false" branch is used only at the top level.
1608     24. When there was a very long string of literal characters (over 255 bytes
1609     without UTF support, over 250 bytes with UTF support), the computation of how
1610     much memory was required could be incorrect, leading to segfaults or other
1611     strange effects.
1613     25. PCRE was incorrectly assuming anchoring (either to start of subject or to
1614     start of line for a non-DOTALL pattern) when a pattern started with (.*) and
1615     there was a subsequent back reference to those brackets. This meant that, for
1616     example, /(.*)\d+\1/ failed to match "abc123bc". Unfortunately, it isn't
1617     possible to check for precisely this case. All we can do is abandon the
1618     optimization if .* occurs inside capturing brackets when there are any back
1619     references whatsoever. (See below for a better fix that came later.)
1621     26. The handling of the optimization for finding the first character of a
1622     non-anchored pattern, and for finding a character that is required later in the
1623     match were failing in some cases. This didn't break the matching; it just
1624     failed to optimize when it could. The way this is done has been re-implemented.
1626     27. Fixed typo in error message for invalid (?R item (it said "(?p").
1628     28. Added a new feature that provides some of the functionality that Perl
1629     provides with (?{...}). The facility is termed a "callout". The way it is done
1630     in PCRE is for the caller to provide an optional function, by setting
1631     pcre_callout to its entry point. Like pcre_malloc and pcre_free, this is a
1632     global variable. By default it is unset, which disables all calling out. To get
1633     the function called, the regex must include (?C) at appropriate points. This
1634     is, in fact, equivalent to (?C0), and any number <= 255 may be given with (?C).
1635     This provides a means of identifying different callout points. When PCRE
1636     reaches such a point in the regex, if pcre_callout has been set, the external
1637     function is called. It is provided with data in a structure called
1638     pcre_callout_block, which is defined in pcre.h. If the function returns 0,
1639     matching continues; if it returns a non-zero value, the match at the current
1640     point fails. However, backtracking will occur if possible. [This was changed
1641     later and other features added - see item 49 below.]
1643     29. pcretest is upgraded to test the callout functionality. It provides a
1644     callout function that displays information. By default, it shows the start of
1645     the match and the current position in the text. There are some new data escapes
1646     to vary what happens:
1648     \C+ in addition, show current contents of captured substrings
1649     \C- do not supply a callout function
1650     \C!n return 1 when callout number n is reached
1651     \C!n!m return 1 when callout number n is reached for the mth time
1653     30. If pcregrep was called with the -l option and just a single file name, it
1654     output "<stdin>" if a match was found, instead of the file name.
1656     31. Improve the efficiency of the POSIX API to PCRE. If the number of capturing
1657     slots is less than POSIX_MALLOC_THRESHOLD, use a block on the stack to pass to
1658     pcre_exec(). This saves a malloc/free per call. The default value of
1659     POSIX_MALLOC_THRESHOLD is 10; it can be changed by --with-posix-malloc-threshold
1660     when configuring.
1662     32. The default maximum size of a compiled pattern is 64K. There have been a
1663     few cases of people hitting this limit. The code now uses macros to handle the
1664     storing of links as offsets within the compiled pattern. It defaults to 2-byte
1665     links, but this can be changed to 3 or 4 bytes by --with-link-size when
1666     configuring. Tests 2 and 5 work only with 2-byte links because they output
1667     debugging information about compiled patterns.
1669     33. Internal code re-arrangements:
1671     (a) Moved the debugging function for printing out a compiled regex into
1672     its own source file (printint.c) and used #include to pull it into
1673     pcretest.c and, when DEBUG is defined, into pcre.c, instead of having two
1674     separate copies.
1676     (b) Defined the list of op-code names for debugging as a macro in
1677     internal.h so that it is next to the definition of the opcodes.
1679     (c) Defined a table of op-code lengths for simpler skipping along compiled
1680     code. This is again a macro in internal.h so that it is next to the
1681     definition of the opcodes.
1683     34. Added support for recursive calls to individual subpatterns, along the
1684     lines of Robin Houston's patch (but implemented somewhat differently).
1686     35. Further mods to the Makefile to help Win32. Also, added code to pcregrep to
1687     allow it to read and process whole directories in Win32. This code was
1688     contributed by Lionel Fourquaux; it has not been tested by me.
1690     36. Added support for named subpatterns. The Python syntax (?P<name>...) is
1691     used to name a group. Names consist of alphanumerics and underscores, and must
1692     be unique. Back references use the syntax (?P=name) and recursive calls use
1693     (?P>name) which is a PCRE extension to the Python extension. Groups still have
1694     numbers. The function pcre_fullinfo() can be used after compilation to extract
1695     a name/number map. There are three relevant calls:
1697     PCRE_INFO_NAMEENTRYSIZE yields the size of each entry in the map
1698     PCRE_INFO_NAMECOUNT yields the number of entries
1699     PCRE_INFO_NAMETABLE yields a pointer to the map.
1701     The map is a vector of fixed-size entries. The size of each entry depends on
1702     the length of the longest name used. The first two bytes of each entry are the
1703     group number, most significant byte first. There follows the corresponding
1704     name, zero terminated. The names are in alphabetical order.
1706     37. Make the maximum literal string in the compiled code 250 for the non-UTF-8
1707     case instead of 255. Making it the same both with and without UTF-8 support
1708     means that the same test output works with both.
1710     38. There was a case of malloc(0) in the POSIX testing code in pcretest. Avoid
1711     calling malloc() with a zero argument.
1713     39. Change 25 above had to resort to a heavy-handed test for the .* anchoring
1714     optimization. I've improved things by keeping a bitmap of backreferences with
1715     numbers 1-31 so that if .* occurs inside capturing brackets that are not in
1716     fact referenced, the optimization can be applied. It is unlikely that a
1717     relevant occurrence of .* (i.e. one which might indicate anchoring or forcing
1718     the match to follow \n) will appear inside brackets with a number greater than
1719     31, but if it does, any back reference > 31 suppresses the optimization.
1721     40. Added a new compile-time option PCRE_NO_AUTO_CAPTURE. This has the effect
1722     of disabling numbered capturing parentheses. Any opening parenthesis that is
1723     not followed by ? behaves as if it were followed by ?: but named parentheses
1724     can still be used for capturing (and they will acquire numbers in the usual
1725     way).
1727     41. Redesigned the return codes from the match() function into yes/no/error so
1728     that errors can be passed back from deep inside the nested calls. A malloc
1729     failure while inside a recursive subpattern call now causes the
1730     PCRE_ERROR_NOMEMORY return instead of quietly going wrong.
1732     42. It is now possible to set a limit on the number of times the match()
1733     function is called in a call to pcre_exec(). This facility makes it possible to
1734     limit the amount of recursion and backtracking, though not in a directly
1735     obvious way, because the match() function is used in a number of different
1736     circumstances. The count starts from zero for each position in the subject
1737     string (for non-anchored patterns). The default limit is, for compatibility, a
1738     large number, namely 10 000 000. You can change this in two ways:
1740     (a) When configuring PCRE before making, you can use --with-match-limit=n
1741     to set a default value for the compiled library.
1743     (b) For each call to pcre_exec(), you can pass a pcre_extra block in which
1744     a different value is set. See 45 below.
1746     If the limit is exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT.
1748     43. Added a new function pcre_config(int, void *) to enable run-time extraction
1749     of things that can be changed at compile time. The first argument specifies
1750     what is wanted and the second points to where the information is to be placed.
1751     The current list of available information is:
1755     The output is an integer that is set to one if UTF-8 support is available;
1756     otherwise it is set to zero.
1760     The output is an integer that it set to the value of the code that is used for
1761     newline. It is either LF (10) or CR (13).
1765     The output is an integer that contains the number of bytes used for internal
1766     linkage in compiled expressions. The value is 2, 3, or 4. See item 32 above.
1770     The output is an integer that contains the threshold above which the POSIX
1771     interface uses malloc() for output vectors. See item 31 above.
1775     The output is an unsigned integer that contains the default limit of the number
1776     of match() calls in a pcre_exec() execution. See 42 above.
1778     44. pcretest has been upgraded by the addition of the -C option. This causes it
1779     to extract all the available output from the new pcre_config() function, and to
1780     output it. The program then exits immediately.
1782     45. A need has arisen to pass over additional data with calls to pcre_exec() in
1783     order to support additional features. One way would have been to define
1784     pcre_exec2() (for example) with extra arguments, but this would not have been
1785     extensible, and would also have required all calls to the original function to
1786     be mapped to the new one. Instead, I have chosen to extend the mechanism that
1787     is used for passing in "extra" data from pcre_study().
1789     The pcre_extra structure is now exposed and defined in pcre.h. It currently
1790     contains the following fields:
1792     flags a bitmap indicating which of the following fields are set
1793     study_data opaque data from pcre_study()
1794     match_limit a way of specifying a limit on match() calls for a specific
1795     call to pcre_exec()
1796     callout_data data for callouts (see 49 below)
1798     The flag bits are also defined in pcre.h, and are
1804     The pcre_study() function now returns one of these new pcre_extra blocks, with
1805     the actual study data pointed to by the study_data field, and the
1806     PCRE_EXTRA_STUDY_DATA flag set. This can be passed directly to pcre_exec() as
1807     before. That is, this change is entirely upwards-compatible and requires no
1808     change to existing code.
1810     If you want to pass in additional data to pcre_exec(), you can either place it
1811     in a pcre_extra block provided by pcre_study(), or create your own pcre_extra
1812     block.
1814     46. pcretest has been extended to test the PCRE_EXTRA_MATCH_LIMIT feature. If a
1815     data string contains the escape sequence \M, pcretest calls pcre_exec() several
1816     times with different match limits, until it finds the minimum value needed for
1817     pcre_exec() to complete. The value is then output. This can be instructive; for
1818     most simple matches the number is quite small, but for pathological cases it
1819     gets very large very quickly.
1821     47. There's a new option for pcre_fullinfo() called PCRE_INFO_STUDYSIZE. It
1822     returns the size of the data block pointed to by the study_data field in a
1823     pcre_extra block, that is, the value that was passed as the argument to
1824     pcre_malloc() when PCRE was getting memory in which to place the information
1825     created by pcre_study(). The fourth argument should point to a size_t variable.
1826     pcretest has been extended so that this information is shown after a successful
1827     pcre_study() call when information about the compiled regex is being displayed.
1829     48. Cosmetic change to Makefile: there's no need to have / after $(DESTDIR)
1830     because what follows is always an absolute path. (Later: it turns out that this
1831     is more than cosmetic for MinGW, because it doesn't like empty path
1832     components.)
1834     49. Some changes have been made to the callout feature (see 28 above):
1836     (i) A callout function now has three choices for what it returns:
1838     0 => success, carry on matching
1839     > 0 => failure at this point, but backtrack if possible
1840     < 0 => serious error, return this value from pcre_exec()
1842     Negative values should normally be chosen from the set of PCRE_ERROR_xxx
1843     values. In particular, returning PCRE_ERROR_NOMATCH forces a standard
1844     "match failed" error. The error number PCRE_ERROR_CALLOUT is reserved for
1845     use by callout functions. It will never be used by PCRE itself.
1847     (ii) The pcre_extra structure (see 45 above) has a void * field called
1848     callout_data, with corresponding flag bit PCRE_EXTRA_CALLOUT_DATA. The
1849     pcre_callout_block structure has a field of the same name. The contents of
1850     the field passed in the pcre_extra structure are passed to the callout
1851     function in the corresponding field in the callout block. This makes it
1852     easier to use the same callout-containing regex from multiple threads. For
1853     testing, the pcretest program has a new data escape
1855     \C*n pass the number n (may be negative) as callout_data
1857     If the callout function in pcretest receives a non-zero value as
1858     callout_data, it returns that value.
1860     50. Makefile wasn't handling CFLAGS properly when compiling dftables. Also,
1861     there were some redundant $(CFLAGS) in commands that are now specified as
1862     $(LINK), which already includes $(CFLAGS).
1864     51. Extensions to UTF-8 support are listed below. These all apply when (a) PCRE
1865     has been compiled with UTF-8 support *and* pcre_compile() has been compiled
1866     with the PCRE_UTF8 flag. Patterns that are compiled without that flag assume
1867     one-byte characters throughout. Note that case-insensitive matching applies
1868     only to characters whose values are less than 256. PCRE doesn't support the
1869     notion of cases for higher-valued characters.
1871     (i) A character class whose characters are all within 0-255 is handled as
1872     a bit map, and the map is inverted for negative classes. Previously, a
1873     character > 255 always failed to match such a class; however it should
1874     match if the class was a negative one (e.g. [^ab]). This has been fixed.
1876     (ii) A negated character class with a single character < 255 is coded as
1877     "not this character" (OP_NOT). This wasn't working properly when the test
1878     character was multibyte, either singly or repeated.
1880     (iii) Repeats of multibyte characters are now handled correctly in UTF-8
1881     mode, for example: \x{100}{2,3}.
1883     (iv) The character escapes \b, \B, \d, \D, \s, \S, \w, and \W (either
1884     singly or repeated) now correctly test multibyte characters. However,
1885     PCRE doesn't recognize any characters with values greater than 255 as
1886     digits, spaces, or word characters. Such characters always match \D, \S,
1887     and \W, and never match \d, \s, or \w.
1889     (v) Classes may now contain characters and character ranges with values
1890     greater than 255. For example: [ab\x{100}-\x{400}].
1892     (vi) pcregrep now has a --utf-8 option (synonym -u) which makes it call
1893     PCRE in UTF-8 mode.
1895     52. The info request value PCRE_INFO_FIRSTCHAR has been renamed
1896     PCRE_INFO_FIRSTBYTE because it is a byte value. However, the old name is
1897     retained for backwards compatibility. (Note that LASTLITERAL is also a byte
1898     value.)
1900     53. The single man page has become too large. I have therefore split it up into
1901     a number of separate man pages. These also give rise to individual HTML pages;
1902     these are now put in a separate directory, and there is an index.html page that
1903     lists them all. Some hyperlinking between the pages has been installed.
1905     54. Added convenience functions for handling named capturing parentheses.
1907     55. Unknown escapes inside character classes (e.g. [\M]) and escapes that
1908     aren't interpreted therein (e.g. [\C]) are literals in Perl. This is now also
1909     true in PCRE, except when the PCRE_EXTENDED option is set, in which case they
1910     are faulted.
1912     56. Introduced HOST_CC and HOST_CFLAGS which can be set in the environment when
1913     calling configure. These values are used when compiling the dftables.c program
1914     which is run to generate the source of the default character tables. They
1915     default to the values of CC and CFLAGS. If you are cross-compiling PCRE,
1916     you will need to set these values.
1918     57. Updated the building process for Windows DLL, as provided by Fred Cox.
1921     Version 3.9 02-Jan-02
1922 nigel 61 ---------------------
1924     1. A bit of extraneous text had somehow crept into the pcregrep documentation.
1926     2. If --disable-static was given, the building process failed when trying to
1927     build pcretest and pcregrep. (For some reason it was using libtool to compile
1928     them, which is not right, as they aren't part of the library.)
1931 nigel 59 Version 3.8 18-Dec-01
1932     ---------------------
1934     1. The experimental UTF-8 code was completely screwed up. It was packing the
1935     bytes in the wrong order. How dumb can you get?
1938 nigel 57 Version 3.7 29-Oct-01
1939     ---------------------
1941     1. In updating pcretest to check change 1 of version 3.6, I screwed up.
1942     This caused pcretest, when used on the test data, to segfault. Unfortunately,
1943     this didn't happen under Solaris 8, where I normally test things.
1945 nigel 59 2. The Makefile had to be changed to make it work on BSD systems, where 'make'
1946     doesn't seem to recognize that ./xxx and xxx are the same file. (This entry
1947     isn't in ChangeLog distributed with 3.7 because I forgot when I hastily made
1948     this fix an hour or so after the initial 3.7 release.)
1949 nigel 57
1950 nigel 59
1951 nigel 55 Version 3.6 23-Oct-01
1952     ---------------------
1954     1. Crashed with /(sens|respons)e and \1ibility/ and "sense and sensibility" if
1955     offsets passed as NULL with zero offset count.
1957     2. The config.guess and config.sub files had not been updated when I moved to
1958     the latest autoconf.
1961 nigel 53 Version 3.5 15-Aug-01
1962     ---------------------
1963 nigel 5
1964 nigel 53 1. Added some missing #if !defined NOPOSIX conditionals in pcretest.c that
1965     had been forgotten.
1967     2. By using declared but undefined structures, we can avoid using "void"
1968     definitions in pcre.h while keeping the internal definitions of the structures
1969     private.
1971     3. The distribution is now built using autoconf 2.50 and libtool 1.4. From a
1972     user point of view, this means that both static and shared libraries are built
1973     by default, but this can be individually controlled. More of the work of
1974     handling this static/shared cases is now inside libtool instead of PCRE's make
1975     file.
1977     4. The pcretest utility is now installed along with pcregrep because it is
1978     useful for users (to test regexs) and by doing this, it automatically gets
1979     relinked by libtool. The documentation has been turned into a man page, so
1980     there are now .1, .txt, and .html versions in /doc.
1982     5. Upgrades to pcregrep:
1983     (i) Added long-form option names like gnu grep.
1984     (ii) Added --help to list all options with an explanatory phrase.
1985     (iii) Added -r, --recursive to recurse into sub-directories.
1986     (iv) Added -f, --file to read patterns from a file.
1988     6. pcre_exec() was referring to its "code" argument before testing that
1989     argument for NULL (and giving an error if it was NULL).
1991     7. Upgraded Makefile.in to allow for compiling in a different directory from
1992     the source directory.
1994     8. Tiny buglet in pcretest: when pcre_fullinfo() was called to retrieve the
1995     options bits, the pointer it was passed was to an int instead of to an unsigned
1996     long int. This mattered only on 64-bit systems.
1998     9. Fixed typo (3.4/1) in pcre.h again. Sigh. I had changed pcre.h (which is
1999     generated) instead of pcre.in, which it its source. Also made the same change
2000     in several of the .c files.
2002     10. A new release of gcc defines printf() as a macro, which broke pcretest
2003     because it had an ifdef in the middle of a string argument for printf(). Fixed
2004     by using separate calls to printf().
2006     11. Added --enable-newline-is-cr and --enable-newline-is-lf to the configure
2007     script, to force use of CR or LF instead of \n in the source. On non-Unix
2008     systems, the value can be set in config.h.
2010     12. The limit of 200 on non-capturing parentheses is a _nesting_ limit, not an
2011     absolute limit. Changed the text of the error message to make this clear, and
2012     likewise updated the man page.
2014     13. The limit of 99 on the number of capturing subpatterns has been removed.
2015     The new limit is 65535, which I hope will not be a "real" limit.
2018 nigel 51 Version 3.4 22-Aug-00
2019     ---------------------
2021     1. Fixed typo in pcre.h: unsigned const char * changed to const unsigned char *.
2023     2. Diagnose condition (?(0) as an error instead of crashing on matching.
2026 nigel 49 Version 3.3 01-Aug-00
2027     ---------------------
2029     1. If an octal character was given, but the value was greater than \377, it
2030     was not getting masked to the least significant bits, as documented. This could
2031     lead to crashes in some systems.
2033     2. Perl 5.6 (if not earlier versions) accepts classes like [a-\d] and treats
2034     the hyphen as a literal. PCRE used to give an error; it now behaves like Perl.
2036     3. Added the functions pcre_free_substring() and pcre_free_substring_list().
2037     These just pass their arguments on to (pcre_free)(), but they are provided
2038     because some uses of PCRE bind it to non-C systems that can call its functions,
2039     but cannot call free() or pcre_free() directly.
2041     4. Add "make test" as a synonym for "make check". Corrected some comments in
2042     the Makefile.
2044     5. Add $(DESTDIR)/ in front of all the paths in the "install" target in the
2045     Makefile.
2047     6. Changed the name of pgrep to pcregrep, because Solaris has introduced a
2048     command called pgrep for grepping around the active processes.
2050     7. Added the beginnings of support for UTF-8 character strings.
2052     8. Arranged for the Makefile to pass over the settings of CC, CFLAGS, and
2053     RANLIB to ./ltconfig so that they are used by libtool. I think these are all
2054     the relevant ones. (AR is not passed because ./ltconfig does its own figuring
2055     out for the ar command.)
2058 nigel 47 Version 3.2 12-May-00
2059     ---------------------
2061     This is purely a bug fixing release.
2063     1. If the pattern /((Z)+|A)*/ was matched agained ZABCDEFG it matched Z instead
2064     of ZA. This was just one example of several cases that could provoke this bug,
2065     which was introduced by change 9 of version 2.00. The code for breaking
2066     infinite loops after an iteration that matches an empty string was't working
2067     correctly.
2069     2. The pcretest program was not imitating Perl correctly for the pattern /a*/g
2070     when matched against abbab (for example). After matching an empty string, it
2071     wasn't forcing anchoring when setting PCRE_NOTEMPTY for the next attempt; this
2072     caused it to match further down the string than it should.
2074     3. The code contained an inclusion of sys/types.h. It isn't clear why this
2075     was there because it doesn't seem to be needed, and it causes trouble on some
2076     systems, as it is not a Standard C header. It has been removed.
2078     4. Made 4 silly changes to the source to avoid stupid compiler warnings that
2079     were reported on the Macintosh. The changes were from
2081     while ((c = *(++ptr)) != 0 && c != '\n');
2082     to
2083     while ((c = *(++ptr)) != 0 && c != '\n') ;
2085     Totally extraordinary, but if that's what it takes...
2087     5. PCRE is being used in one environment where neither memmove() nor bcopy() is
2088     available. Added HAVE_BCOPY and an autoconf test for it; if neither
2089     HAVE_MEMMOVE nor HAVE_BCOPY is set, use a built-in emulation function which
2090     assumes the way PCRE uses memmove() (always moving upwards).
2092     6. PCRE is being used in one environment where strchr() is not available. There
2093     was only one use in pcre.c, and writing it out to avoid strchr() probably gives
2094     faster code anyway.
2097 nigel 45 Version 3.1 09-Feb-00
2098     ---------------------
2100     The only change in this release is the fixing of some bugs in Makefile.in for
2101     the "install" target:
2103     (1) It was failing to install pcreposix.h.
2105     (2) It was overwriting the pcre.3 man page with the pcreposix.3 man page.
2108 nigel 43 Version 3.0 01-Feb-00
2109     ---------------------
2110 nigel 41
2111     1. Add support for the /+ modifier to perltest (to output $` like it does in
2112     pcretest).
2114     2. Add support for the /g modifier to perltest.
2116     3. Fix pcretest so that it behaves even more like Perl for /g when the pattern
2117     matches null strings.
2119     4. Fix perltest so that it doesn't do unwanted things when fed an empty
2120     pattern. Perl treats empty patterns specially - it reuses the most recent
2121     pattern, which is not what we want. Replace // by /(?#)/ in order to avoid this
2122     effect.
2124     5. The POSIX interface was broken in that it was just handing over the POSIX
2125     captured string vector to pcre_exec(), but (since release 2.00) PCRE has
2126     required a bigger vector, with some working space on the end. This means that
2127     the POSIX wrapper now has to get and free some memory, and copy the results.
2129 nigel 43 6. Added some simple autoconf support, placing the test data and the
2130     documentation in separate directories, re-organizing some of the
2131     information files, and making it build pcre-config (a GNU standard). Also added
2132     libtool support for building PCRE as a shared library, which is now the
2133     default.
2134 nigel 41
2135 nigel 43 7. Got rid of the leading zero in the definition of PCRE_MINOR because 08 and
2136     09 are not valid octal constants. Single digits will be used for minor values
2137     less than 10.
2139     8. Defined REG_EXTENDED and REG_NOSUB as zero in the POSIX header, so that
2140     existing programs that set these in the POSIX interface can use PCRE without
2141     modification.
2143     9. Added a new function, pcre_fullinfo() with an extensible interface. It can
2144     return all that pcre_info() returns, plus additional data. The pcre_info()
2145     function is retained for compatibility, but is considered to be obsolete.
2147     10. Added experimental recursion feature (?R) to handle one common case that
2148     Perl 5.6 will be able to do with (?p{...}).
2150     11. Added support for POSIX character classes like [:alpha:], which Perl is
2151     adopting.
2154 nigel 39 Version 2.08 31-Aug-99
2155     ----------------------
2157     1. When startoffset was not zero and the pattern began with ".*", PCRE was not
2158     trying to match at the startoffset position, but instead was moving forward to
2159     the next newline as if a previous match had failed.
2161     2. pcretest was not making use of PCRE_NOTEMPTY when repeating for /g and /G,
2162     and could get into a loop if a null string was matched other than at the start
2163     of the subject.
2165     3. Added definitions of PCRE_MAJOR and PCRE_MINOR to pcre.h so the version can
2166     be distinguished at compile time, and for completeness also added PCRE_DATE.
2168     5. Added Paul Sokolovsky's minor changes to make it easy to compile a Win32 DLL
2169     in GnuWin32 environments.
2172 nigel 37 Version 2.07 29-Jul-99
2173     ----------------------
2175     1. The documentation is now supplied in plain text form and HTML as well as in
2176     the form of man page sources.
2178     2. C++ compilers don't like assigning (void *) values to other pointer types.
2179     In particular this affects malloc(). Although there is no problem in Standard
2180     C, I've put in casts to keep C++ compilers happy.
2182     3. Typo on pcretest.c; a cast of (unsigned char *) in the POSIX regexec() call
2183     should be (const char *).
2185     4. If NOPOSIX is defined, pcretest.c compiles without POSIX support. This may
2186     be useful for non-Unix systems who don't want to bother with the POSIX stuff.
2187     However, I haven't made this a standard facility. The documentation doesn't
2188     mention it, and the Makefile doesn't support it.
2190     5. The Makefile now contains an "install" target, with editable destinations at
2191     the top of the file. The pcretest program is not installed.
2193     6. pgrep -V now gives the PCRE version number and date.
2195     7. Fixed bug: a zero repetition after a literal string (e.g. /abcde{0}/) was
2196     causing the entire string to be ignored, instead of just the last character.
2198     8. If a pattern like /"([^\\"]+|\\.)*"/ is applied in the normal way to a
2199     non-matching string, it can take a very, very long time, even for strings of
2200     quite modest length, because of the nested recursion. PCRE now does better in
2201     some of these cases. It does this by remembering the last required literal
2202     character in the pattern, and pre-searching the subject to ensure it is present
2203     before running the real match. In other words, it applies a heuristic to detect
2204     some types of certain failure quickly, and in the above example, if presented
2205     with a string that has no trailing " it gives "no match" very quickly.
2207     9. A new runtime option PCRE_NOTEMPTY causes null string matches to be ignored;
2208     other alternatives are tried instead.
2211 nigel 35 Version 2.06 09-Jun-99
2212     ----------------------
2214     1. Change pcretest's output for amount of store used to show just the code
2215     space, because the remainder (the data block) varies in size between 32-bit and
2216     64-bit systems.
2218     2. Added an extra argument to pcre_exec() to supply an offset in the subject to
2219     start matching at. This allows lookbehinds to work when searching for multiple
2220     occurrences in a string.
2222     3. Added additional options to pcretest for testing multiple occurrences:
2224     /+ outputs the rest of the string that follows a match
2225     /g loops for multiple occurrences, using the new startoffset argument
2226     /G loops for multiple occurrences by passing an incremented pointer
2228     4. PCRE wasn't doing the "first character" optimization for patterns starting
2229     with \b or \B, though it was doing it for other lookbehind assertions. That is,
2230     it wasn't noticing that a match for a pattern such as /\bxyz/ has to start with
2231     the letter 'x'. On long subject strings, this gives a significant speed-up.
2234 nigel 33 Version 2.05 21-Apr-99
2235     ----------------------
2237     1. Changed the type of magic_number from int to long int so that it works
2238     properly on 16-bit systems.
2240     2. Fixed a bug which caused patterns starting with .* not to work correctly
2241     when the subject string contained newline characters. PCRE was assuming
2242     anchoring for such patterns in all cases, which is not correct because .* will
2243     not pass a newline unless PCRE_DOTALL is set. It now assumes anchoring only if
2244     DOTALL is set at top level; otherwise it knows that patterns starting with .*
2245     must be retried after every newline in the subject.
2248 nigel 31 Version 2.04 18-Feb-99
2249     ----------------------
2251     1. For parenthesized subpatterns with repeats whose minimum was zero, the
2252     computation of the store needed to hold the pattern was incorrect (too large).
2253     If such patterns were nested a few deep, this could multiply and become a real
2254     problem.
2256     2. Added /M option to pcretest to show the memory requirement of a specific
2257     pattern. Made -m a synonym of -s (which does this globally) for compatibility.
2259     3. Subpatterns of the form (regex){n,m} (i.e. limited maximum) were being
2260     compiled in such a way that the backtracking after subsequent failure was
2261     pessimal. Something like (a){0,3} was compiled as (a)?(a)?(a)? instead of
2262     ((a)((a)(a)?)?)? with disastrous performance if the maximum was of any size.
2265 nigel 29 Version 2.03 02-Feb-99
2266     ----------------------
2268     1. Fixed typo and small mistake in man page.
2270 nigel 31 2. Added 4th condition (GPL supersedes if conflict) and created separate
2271     LICENCE file containing the conditions.
2272 nigel 29
2273     3. Updated pcretest so that patterns such as /abc\/def/ work like they do in
2274     Perl, that is the internal \ allows the delimiter to be included in the
2275     pattern. Locked out the use of \ as a delimiter. If \ immediately follows
2276     the final delimiter, add \ to the end of the pattern (to test the error).
2278     4. Added the convenience functions for extracting substrings after a successful
2279     match. Updated pcretest to make it able to test these functions.
2282 nigel 27 Version 2.02 14-Jan-99
2283     ----------------------
2285     1. Initialized the working variables associated with each extraction so that
2286     their saving and restoring doesn't refer to uninitialized store.
2288     2. Put dummy code into study.c in order to trick the optimizer of the IBM C
2289     compiler for OS/2 into generating correct code. Apparently IBM isn't going to
2290     fix the problem.
2292     3. Pcretest: the timing code wasn't using LOOPREPEAT for timing execution
2293     calls, and wasn't printing the correct value for compiling calls. Increased the
2294     default value of LOOPREPEAT, and the number of significant figures in the
2295     times.
2297     4. Changed "/bin/rm" in the Makefile to "-rm" so it works on Windows NT.
2299     5. Renamed "deftables" as "dftables" to get it down to 8 characters, to avoid
2300     a building problem on Windows NT with a FAT file system.
2303 nigel 25 Version 2.01 21-Oct-98
2304     ----------------------
2306     1. Changed the API for pcre_compile() to allow for the provision of a pointer
2307     to character tables built by pcre_maketables() in the current locale. If NULL
2308     is passed, the default tables are used.
2311 nigel 23 Version 2.00 24-Sep-98
2312 nigel 21 ----------------------
2314 nigel 23 1. Since the (>?) facility is in Perl 5.005, don't require PCRE_EXTRA to enable
2315     it any more.
2317     2. Allow quantification of (?>) groups, and make it work correctly.
2319     3. The first character computation wasn't working for (?>) groups.
2321     4. Correct the implementation of \Z (it is permitted to match on the \n at the
2322     end of the subject) and add 5.005's \z, which really does match only at the
2323     very end of the subject.
2325     5. Remove the \X "cut" facility; Perl doesn't have it, and (?> is neater.
2327     6. Remove the ability to specify CASELESS, MULTILINE, DOTALL, and
2328     DOLLAR_END_ONLY at runtime, to make it possible to implement the Perl 5.005
2329     localized options. All options to pcre_study() were also removed.
2331     7. Add other new features from 5.005:
2333     $(?<= positive lookbehind
2334     $(?<! negative lookbehind
2335     (?imsx-imsx) added the unsetting capability
2336     such a setting is global if at outer level; local otherwise
2337     (?imsx-imsx:) non-capturing groups with option setting
2338     (?(cond)re|re) conditional pattern matching
2340     A backreference to itself in a repeated group matches the previous
2341     captured string.
2343     8. General tidying up of studying (both automatic and via "study")
2344     consequential on the addition of new assertions.
2346     9. As in 5.005, unlimited repeated groups that could match an empty substring
2347     are no longer faulted at compile time. Instead, the loop is forcibly broken at
2348     runtime if any iteration does actually match an empty substring.
2350     10. Include the RunTest script in the distribution.
2352     11. Added tests from the Perl 5.005_02 distribution. This showed up a few
2353     discrepancies, some of which were old and were also with respect to 5.004. They
2354     have now been fixed.
2357     Version 1.09 28-Apr-98
2358     ----------------------
2360 nigel 21 1. A negated single character class followed by a quantifier with a minimum
2361     value of one (e.g. [^x]{1,6} ) was not compiled correctly. This could lead to
2362     program crashes, or just wrong answers. This did not apply to negated classes
2363     containing more than one character, or to minima other than one.
2366 nigel 19 Version 1.08 27-Mar-98
2367     ----------------------
2369     1. Add PCRE_UNGREEDY to invert the greediness of quantifiers.
2371     2. Add (?U) and (?X) to set PCRE_UNGREEDY and PCRE_EXTRA respectively. The
2372     latter must appear before anything that relies on it in the pattern.
2375 nigel 17 Version 1.07 16-Feb-98
2376     ----------------------
2378     1. A pattern such as /((a)*)*/ was not being diagnosed as in error (unlimited
2379     repeat of a potentially empty string).
2382 nigel 15 Version 1.06 23-Jan-98
2383     ----------------------
2385     1. Added Markus Oberhumer's little patches for C++.
2387     2. Literal strings longer than 255 characters were broken.
2390 nigel 13 Version 1.05 23-Dec-97
2391     ----------------------
2393     1. Negated character classes containing more than one character were failing if
2394     PCRE_CASELESS was set at run time.
2397 nigel 11 Version 1.04 19-Dec-97
2398     ----------------------
2400     1. Corrected the man page, where some "const" qualifiers had been omitted.
2402     2. Made debugging output print "{0,xxx}" instead of just "{,xxx}" to agree with
2403     input syntax.
2405     3. Fixed memory leak which occurred when a regex with back references was
2406     matched with an offsets vector that wasn't big enough. The temporary memory
2407     that is used in this case wasn't being freed if the match failed.
2409     4. Tidied pcretest to ensure it frees memory that it gets.
2411     5. Temporary memory was being obtained in the case where the passed offsets
2412     vector was exactly big enough.
2414     6. Corrected definition of offsetof() from change 5 below.
2416     7. I had screwed up change 6 below and broken the rules for the use of
2417     setjmp(). Now fixed.
2420 nigel 9 Version 1.03 18-Dec-97
2421     ----------------------
2423     1. A erroneous regex with a missing opening parenthesis was correctly
2424     diagnosed, but PCRE attempted to access brastack[-1], which could cause crashes
2425     on some systems.
2427     2. Replaced offsetof(real_pcre, code) by offsetof(real_pcre, code[0]) because
2428     it was reported that one broken compiler failed on the former because "code" is
2429     also an independent variable.
2431     3. The erroneous regex a[]b caused an array overrun reference.
2433     4. A regex ending with a one-character negative class (e.g. /[^k]$/) did not
2434     fail on data ending with that character. (It was going on too far, and checking
2435     the next character, typically a binary zero.) This was specific to the
2436     optimized code for single-character negative classes.
2438     5. Added a contributed patch from the TIN world which does the following:
2440     + Add an undef for memmove, in case the the system defines a macro for it.
2442     + Add a definition of offsetof(), in case there isn't one. (I don't know
2443     the reason behind this - offsetof() is part of the ANSI standard - but
2444     it does no harm).
2446     + Reduce the ifdef's in pcre.c using macro DPRINTF, thereby eliminating
2447     most of the places where whitespace preceded '#'. I have given up and
2448     allowed the remaining 2 cases to be at the margin.
2450     + Rename some variables in pcre to eliminate shadowing. This seems very
2451     pedantic, but does no harm, of course.
2453     6. Moved the call to setjmp() into its own function, to get rid of warnings
2454     from gcc -Wall, and avoided calling it at all unless PCRE_EXTRA is used.
2456     7. Constructs such as \d{8,} were compiling into the equivalent of
2457 nigel 11 \d{8}\d{0,65527} instead of \d{8}\d* which didn't make much difference to the
2458 nigel 9 outcome, but in this particular case used more store than had been allocated,
2459     which caused the bug to be discovered because it threw up an internal error.
2461     8. The debugging code in both pcre and pcretest for outputting the compiled
2462     form of a regex was going wrong in the case of back references followed by
2463     curly-bracketed repeats.
2466 nigel 7 Version 1.02 12-Dec-97
2467     ----------------------
2469     1. Typos in pcre.3 and comments in the source fixed.
2471     2. Applied a contributed patch to get rid of places where it used to remove
2472     'const' from variables, and fixed some signed/unsigned and uninitialized
2473     variable warnings.
2475     3. Added the "runtest" target to Makefile.
2477     4. Set default compiler flag to -O2 rather than just -O.
2480 nigel 5 Version 1.01 19-Nov-97
2481     ----------------------
2483     1. PCRE was failing to diagnose unlimited repeat of empty string for patterns
2484     like /([ab]*)*/, that is, for classes with more than one character in them.
2486     2. Likewise, it wasn't diagnosing patterns with "once-only" subpatterns, such
2487     as /((?>a*))*/ (a PCRE_EXTRA facility).
2490     Version 1.00 18-Nov-97
2491     ----------------------
2493     1. Added compile-time macros to support systems such as SunOS4 which don't have
2494     memmove() or strerror() but have other things that can be used instead.
2496     2. Arranged that "make clean" removes the executables.
2499 nigel 3 Version 0.99 27-Oct-97
2500     ----------------------
2502     1. Fixed bug in code for optimizing classes with only one character. It was
2503     initializing a 32-byte map regardless, which could cause it to run off the end
2504     of the memory it had got.
2506     2. Added, conditional on PCRE_EXTRA, the proposed (?>REGEX) construction.
2509     Version 0.98 22-Oct-97
2510     ----------------------
2512     1. Fixed bug in code for handling temporary memory usage when there are more
2513     back references than supplied space in the ovector. This could cause segfaults.
2516     Version 0.97 21-Oct-97
2517     ----------------------
2519     1. Added the \X "cut" facility, conditional on PCRE_EXTRA.
2521     2. Optimized negated single characters not to use a bit map.
2523     3. Brought error texts together as macro definitions; clarified some of them;
2524     fixed one that was wrong - it said "range out of order" when it meant "invalid
2525     escape sequence".
2527     4. Changed some char * arguments to const char *.
2529     5. Added PCRE_NOTBOL and PCRE_NOTEOL (from POSIX).
2531     6. Added the POSIX-style API wrapper in pcreposix.a and testing facilities in
2532     pcretest.
2535     Version 0.96 16-Oct-97
2536     ----------------------
2538     1. Added a simple "pgrep" utility to the distribution.
2540     2. Fixed an incompatibility with Perl: "{" is now treated as a normal character
2541     unless it appears in one of the precise forms "{ddd}", "{ddd,}", or "{ddd,ddd}"
2542     where "ddd" means "one or more decimal digits".
2544     3. Fixed serious bug. If a pattern had a back reference, but the call to
2545     pcre_exec() didn't supply a large enough ovector to record the related
2546     identifying subpattern, the match always failed. PCRE now remembers the number
2547     of the largest back reference, and gets some temporary memory in which to save
2548     the offsets during matching if necessary, in order to ensure that
2549     backreferences always work.
2551     4. Increased the compatibility with Perl in a number of ways:
2553     (a) . no longer matches \n by default; an option PCRE_DOTALL is provided
2554     to request this handling. The option can be set at compile or exec time.
2556     (b) $ matches before a terminating newline by default; an option
2557     PCRE_DOLLAR_ENDONLY is provided to override this (but not in multiline
2558     mode). The option can be set at compile or exec time.
2560     (c) The handling of \ followed by a digit other than 0 is now supposed to be
2561     the same as Perl's. If the decimal number it represents is less than 10
2562     or there aren't that many previous left capturing parentheses, an octal
2563     escape is read. Inside a character class, it's always an octal escape,
2564     even if it is a single digit.
2566     (d) An escaped but undefined alphabetic character is taken as a literal,
2567     unless PCRE_EXTRA is set. Currently this just reserves the remaining
2568     escapes.
2570     (e) {0} is now permitted. (The previous item is removed from the compiled
2571     pattern).
2573     5. Changed all the names of code files so that the basic parts are no longer
2574     than 10 characters, and abolished the teeny "globals.c" file.
2576     6. Changed the handling of character classes; they are now done with a 32-byte
2577     bit map always.
2579     7. Added the -d and /D options to pcretest to make it possible to look at the
2580     internals of compilation without having to recompile pcre.
2583     Version 0.95 23-Sep-97
2584     ----------------------
2586     1. Fixed bug in pre-pass concerning escaped "normal" characters such as \x5c or
2587     \x20 at the start of a run of normal characters. These were being treated as
2588     real characters, instead of the source characters being re-checked.
2591     Version 0.94 18-Sep-97
2592     ----------------------
2594     1. The functions are now thread-safe, with the caveat that the global variables
2595     containing pointers to malloc() and free() or alternative functions are the
2596     same for all threads.
2598     2. Get pcre_study() to generate a bitmap of initial characters for non-
2599     anchored patterns when this is possible, and use it if passed to pcre_exec().
2602     Version 0.93 15-Sep-97
2603     ----------------------
2605     1. /(b)|(:+)/ was computing an incorrect first character.
2607     2. Add pcre_study() to the API and the passing of pcre_extra to pcre_exec(),
2608     but not actually doing anything yet.
2610     3. Treat "-" characters in classes that cannot be part of ranges as literals,
2611     as Perl does (e.g. [-az] or [az-]).
2613     4. Set the anchored flag if a branch starts with .* or .*? because that tests
2614     all possible positions.
2616     5. Split up into different modules to avoid including unneeded functions in a
2617     compiled binary. However, compile and exec are still in one module. The "study"
2618     function is split off.
2620     6. The character tables are now in a separate module whose source is generated
2621     by an auxiliary program - but can then be edited by hand if required. There are
2622     now no calls to isalnum(), isspace(), isdigit(), isxdigit(), tolower() or
2623     toupper() in the code.
2625     7. Turn the malloc/free funtions variables into pcre_malloc and pcre_free and
2626     make them global. Abolish the function for setting them, as the caller can now
2627     set them directly.
2630     Version 0.92 11-Sep-97
2631     ----------------------
2633     1. A repeat with a fixed maximum and a minimum of 1 for an ordinary character
2634     (e.g. /a{1,3}/) was broken (I mis-optimized it).
2636     2. Caseless matching was not working in character classes if the characters in
2637     the pattern were in upper case.
2639     3. Make ranges like [W-c] work in the same way as Perl for caseless matching.
2641     4. Make PCRE_ANCHORED public and accept as a compile option.
2643     5. Add an options word to pcre_exec() and accept PCRE_ANCHORED and
2644     PCRE_CASELESS at run time. Add escapes \A and \I to pcretest to cause it to
2645     pass them.
2647     6. Give an error if bad option bits passed at compile or run time.
2649     7. Add PCRE_MULTILINE at compile and exec time, and (?m) as well. Add \M to
2650     pcretest to cause it to pass that flag.
2652     8. Add pcre_info(), to get the number of identifying subpatterns, the stored
2653     options, and the first character, if set.
2655     9. Recognize C+ or C{n,m} where n >= 1 as providing a fixed starting character.
2658     Version 0.91 10-Sep-97
2659     ----------------------
2661     1. PCRE was failing to diagnose unlimited repeats of subpatterns that could
2662     match the empty string as in /(a*)*/. It was looping and ultimately crashing.
2664     2. PCRE was looping on encountering an indefinitely repeated back reference to
2665     a subpattern that had matched an empty string, e.g. /(a|)\1*/. It now does what
2666     Perl does - treats the match as successful.
2668     ****


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