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Revision 195 - (hide annotations) (download)
Mon Jul 30 13:23:28 2007 UTC (7 years, 8 months ago) by ph10
File size: 131434 byte(s)
Add words about EBCDIC to doc and ./configure --help (somebody thought it might
be a useful option and tried it on an ASCII system). Fixed one missing table
entry for EBCDIC. 

1 nigel 3 ChangeLog for PCRE
2     ------------------
4 ph10 189 Version 7.3 05-Jul-07
5 ph10 157 ---------------------
7 ph10 189 1. In the rejigging of the build system that eventually resulted in 7.1, the
8     line "#include <pcre.h>" was included in pcre_internal.h. The use of angle
9     brackets there is not right, since it causes compilers to look for an
10     installed pcre.h, not the version that is in the source that is being
11     compiled (which of course may be different). I have changed it back to:
13     #include "pcre.h"
15     I have a vague recollection that the change was concerned with compiling in
16     different directories, but in the new build system, that is taken care of
17     by the VPATH setting the Makefile.
18 ph10 190
19     2. The pattern .*$ when run in not-DOTALL UTF-8 mode with newline=any failed
20     when the subject happened to end in the byte 0x85 (e.g. if the last
21     character was \x{1ec5}). *Character* 0x85 is one of the "any" newline
22     characters but of course it shouldn't be taken as a newline when it is part
23     of another character. The bug was that, for an unlimited repeat of . in
24     not-DOTALL UTF-8 mode, PCRE was advancing by bytes rather than by
25     characters when looking for a newline.
27     3. A small performance improvement in the DOTALL UTF-8 mode .* case.
28 ph10 192
29     4. Debugging: adjusted the names of opcodes for different kinds of parentheses
30     in debug output.
31 ph10 193
32     5. Arrange to use "%I64d" instead of "%lld" for long printing in the pcrecpp
33     unittest when running under MinGW.
34 ph10 195
35     6. ESC_K was left out of the EBCDIC table.
36 ph10 189
39     Version 7.2 19-Jun-07
40     ---------------------
42 ph10 157 1. If the fr_FR locale cannot be found for test 3, try the "french" locale,
43     which is apparently normally available under Windows.
44 ph10 159
45     2. Re-jig the pcregrep tests with different newline settings in an attempt
46     to make them independent of the local environment's newline setting.
47 ph10 157
48 ph10 160 3. Add code to configure.ac to remove -g from the CFLAGS default settings.
49 ph10 165
50 ph10 161 4. Some of the "internals" tests were previously cut out when the link size
51     was not 2, because the output contained actual offsets. The recent new
52 ph10 165 "Z" feature of pcretest means that these can be cut out, making the tests
53     usable with all link sizes.
55 ph10 164 5. Implemented Stan Switzer's goto replacement for longjmp() when not using
56     stack recursion. This gives a massive performance boost under BSD, but just
57 ph10 165 a small improvement under Linux. However, it saves one field in the frame
58 ph10 164 in all cases.
59 ph10 172
60 ph10 166 6. Added more features from the forthcoming Perl 5.10:
61 ph10 172
62 ph10 166 (a) (?-n) (where n is a string of digits) is a relative subroutine or
63     recursion call. It refers to the nth most recently opened parentheses.
64 ph10 172
65 ph10 166 (b) (?+n) is also a relative subroutine call; it refers to the nth next
66 ph10 172 to be opened parentheses.
68     (c) Conditions that refer to capturing parentheses can be specified
69 ph10 167 relatively, for example, (?(-2)... or (?(+3)...
70 ph10 172
71 ph10 168 (d) \K resets the start of the current match so that everything before
72 ph10 172 is not part of it.
74 ph10 171 (e) \k{name} is synonymous with \k<name> and \k'name' (.NET compatible).
75 ph10 172
76 ph10 171 (f) \g{name} is another synonym - part of Perl 5.10's unification of
77 ph10 172 reference syntax.
78 ph10 182
79 ph10 175 (g) (?| introduces a group in which the numbering of parentheses in each
80 ph10 182 alternative starts with the same number.
81 ph10 172
82 ph10 182 (h) \h, \H, \v, and \V match horizontal and vertical whitespace.
84 ph10 172 7. Added two new calls to pcre_fullinfo(): PCRE_INFO_OKPARTIAL and
87     8. A pattern such as (.*(.)?)* caused pcre_exec() to fail by either not
88     terminating or by crashing. Diagnosed by Viktor Griph; it was in the code
89 ph10 170 for detecting groups that can match an empty string.
90 ph10 159
91 ph10 172 9. A pattern with a very large number of alternatives (more than several
92     hundred) was running out of internal workspace during the pre-compile
93     phase, where pcre_compile() figures out how much memory will be needed. A
94     bit of new cunning has reduced the workspace needed for groups with
95     alternatives. The 1000-alternative test pattern now uses 12 bytes of
96     workspace instead of running out of the 4096 that are available.
97 ph10 182
98 ph10 176 10. Inserted some missing (unsigned int) casts to get rid of compiler warnings.
99 ph10 172
100 ph10 179 11. Applied patch from Google to remove an optimization that didn't quite work.
101     The report of the bug said:
102 ph10 182
103 ph10 179 pcrecpp::RE("a*").FullMatch("aaa") matches, while
104     pcrecpp::RE("a*?").FullMatch("aaa") does not, and
105 ph10 182 pcrecpp::RE("a*?\\z").FullMatch("aaa") does again.
106 ph10 185
107 ph10 184 12. If \p or \P was used in non-UTF-8 mode on a character greater than 127
108 ph10 185 it matched the wrong number of bytes.
109 ph10 172
110 ph10 179
111 ph10 155 Version 7.1 24-Apr-07
112 ph10 98 ---------------------
114 ph10 111 1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
115 ph10 122 that is more "standard", making use of automake and other Autotools. There
116 ph10 99 is some re-arrangement of the files and adjustment of comments consequent
117     on this.
118 ph10 111
119     2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
120     for recursive directory scanning broke on some systems because the files
121     are not scanned in any specific order and on different systems the order
122     was different. A call to "sort" has been inserted into RunGrepTest for the
123     approprate test as a short-term fix. In the longer term there may be an
124 ph10 100 alternative.
125 ph10 111
126 ph10 100 3. I had an email from Eric Raymond about problems translating some of PCRE's
127 ph10 111 man pages to HTML (despite the fact that I distribute HTML pages, some
128     people do their own conversions for various reasons). The problems
129     concerned the use of low-level troff macros .br and .in. I have therefore
130     removed all such uses from the man pages (some were redundant, some could
131 ph10 113 be replaced by .nf/.fi pairs). The 132html script that I use to generate
132     HTML has been updated to handle .nf/.fi and to complain if it encounters
133     .br or .in.
134 ph10 111
135 ph10 100 4. Updated comments in configure.ac that get placed in config.h.in and also
136 ph10 123 arranged for config.h to be included in the distribution, with the name
137 ph10 111 config.h.generic, for the benefit of those who have to compile without
138     Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
140     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
141     Weber: (1) pcre_internal.h was missing some function renames; (2) updated
142 ph10 127 makevp.bat for the current PCRE, using the additional files
143 ph10 135 makevp_c.txt, makevp_l.txt, and pcregexp.pas.
144 ph10 111
145     6. A Windows user reported a minor discrepancy with test 2, which turned out
146     to be caused by a trailing space on an input line that had got lost in his
147 ph10 102 copy. The trailing space was an accident, so I've just removed it.
148 ph10 111
149 ph10 104 7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
150 ph10 111 that is needed.
152 ph10 105 8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
153     as "const" (a) because they are and (b) because it helps the PHP
154     maintainers who have recently made a script to detect big data structures
155 ph10 111 in the php code that should be moved to the .rodata section. I remembered
156     to update Builducptable as well, so it won't revert if ucptable.h is ever
157 ph10 105 re-created.
158 ph10 111
159     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
160 ph10 107 pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
161 ph10 111 order to be able to cut out the UTF-8 tables in the latter when UTF-8
162     support is not required. This saves 1.5-2K of code, which is important in
163 ph10 107 some applications.
164 ph10 111
165 ph10 110 Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
166 ph10 111 so as not to refer to the tables, even though these functions will never be
167     called when UTF-8 support is disabled. Otherwise there are problems with a
168     shared library.
170 ph10 118 10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
172     (a) It was defining its arguments as char * instead of void *.
174 ph10 123 (b) It was assuming that all moves were upwards in memory; this was true
175     a long time ago when I wrote it, but is no longer the case.
177 ph10 118 The emulated memove() is provided for those environments that have neither
178 ph10 123 memmove() nor bcopy(). I didn't think anyone used it these days, but that
179 ph10 118 is clearly not the case, as these two bugs were recently reported.
180 ph10 123
181 ph10 111 11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
182 ph10 123 and Detrail to create the HTML documentation, the .txt form of the man
183     pages, and it removes trailing spaces from listed files. It also creates
184     pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
185     case, it wraps all the #defines with #ifndefs. This script should be run
186 ph10 111 before "make dist".
187 ph10 123
188 ph10 115 12. Fixed two fairly obscure bugs concerned with quantified caseless matching
189     with Unicode property support.
190 ph10 123
191     (a) For a maximizing quantifier, if the two different cases of the
192     character were of different lengths in their UTF-8 codings (there are
193     some cases like this - I found 11), and the matching function had to
194 ph10 115 back up over a mixture of the two cases, it incorrectly assumed they
195     were both the same length.
196 ph10 123
197     (b) When PCRE was configured to use the heap rather than the stack for
198     recursion during matching, it was not correctly preserving the data for
199     the other case of a UTF-8 character when checking ahead for a match
200     while processing a minimizing repeat. If the check also involved
201 ph10 115 matching a wide character, but failed, corruption could cause an
202     erroneous result when trying to check for a repeat of the original
203     character.
204 ph10 123
205 ph10 116 13. Some tidying changes to the testing mechanism:
206 ph10 98
207 ph10 116 (a) The RunTest script now detects the internal link size and whether there
208     is UTF-8 and UCP support by running ./pcretest -C instead of relying on
209 ph10 123 values substituted by "configure". (The RunGrepTest script already did
210     this for UTF-8.) The configure.ac script no longer substitutes the
211     relevant variables.
213 ph10 116 (b) The debugging options /B and /D in pcretest show the compiled bytecode
214     with length and offset values. This means that the output is different
215     for different internal link sizes. Test 2 is skipped for link sizes
216     other than 2 because of this, bypassing the problem. Unfortunately,
217     there was also a test in test 3 (the locale tests) that used /B and
218 ph10 123 failed for link sizes other than 2. Rather than cut the whole test out,
219     I have added a new /Z option to pcretest that replaces the length and
220     offset values with spaces. This is now used to make test 3 independent
221 ph10 122 of link size. (Test 2 will be tidied up later.)
222 ph10 123
223     14. If erroroffset was passed as NULL to pcre_compile, it provoked a
224 ph10 122 segmentation fault instead of returning the appropriate error message.
225 ph10 134
226 ph10 131 15. In multiline mode when the newline sequence was set to "any", the pattern
227 ph10 134 ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
228     This doesn't seem right; it now treats the CRLF combination as the line
229     ending, and so does not match in that case. It's only a pattern such as ^$
230     that would hit this one: something like ^ABC$ would have failed after \r
231     and then tried again after \r\n.
233 ph10 131 16. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
234 ph10 134 in an attempt to make files that differ only in their line terminators
235     compare equal. This works on Linux.
236 ph10 142
237 ph10 141 17. Under certain error circumstances pcregrep might try to free random memory
238     as it exited. This is now fixed, thanks to valgrind.
239 ph10 142
240 ph10 141 19. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
241 ph10 142 "abc\r\n\r\n", it found an unwanted second match after the second \r. This
242     was because its rules for how to advance for /g after matching an empty
243 ph10 143 string at the end of a line did not allow for this case. They now check for
244     it specially.
245 ph10 150
246     20. pcretest is supposed to handle patterns and data of any length, by
247     extending its buffers when necessary. It was getting this wrong when the
248 ph10 147 buffer for a data line had to be extended.
249 ph10 150
250 ph10 149 21. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or
251 ph10 150 CRLF as a newline sequence.
252 ph10 152
253 ph10 151 22. Code for handling Unicode properties in pcre_dfa_exec() wasn't being cut
254 ph10 152 out by #ifdef SUPPORT_UCP. This did no harm, as it could never be used, but
255     I have nevertheless tidied it up.
256 ph10 111
257 ph10 152 23. Added some casts to kill warnings from HP-UX ia64 compiler.
258 ph10 123
259 ph10 153 24. Added a man page for pcre-config.
260 ph10 152
261 ph10 153
262 nigel 93 Version 7.0 19-Dec-06
263     ---------------------
265     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
266     moving to gcc 4.1.1.
268     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
269     sys/time.h, which is documented as needed for this function. It doesn't
270     seem to matter on Linux, but it showed up on some releases of OS X.
272     3. It seems that there are systems where bytes whose values are greater than
273     127 match isprint() in the "C" locale. The "C" locale should be the
274     default when a C program starts up. In most systems, only ASCII printing
275     characters match isprint(). This difference caused the output from pcretest
276     to vary, making some of the tests fail. I have changed pcretest so that:
278     (a) When it is outputting text in the compiled version of a pattern, bytes
279     other than 32-126 are always shown as hex escapes.
281     (b) When it is outputting text that is a matched part of a subject string,
282     it does the same, unless a different locale has been set for the match
283     (using the /L modifier). In this case, it uses isprint() to decide.
285     4. Fixed a major bug that caused incorrect computation of the amount of memory
286     required for a compiled pattern when options that changed within the
287     pattern affected the logic of the preliminary scan that determines the
288     length. The relevant options are -x, and -i in UTF-8 mode. The result was
289     that the computed length was too small. The symptoms of this bug were
290     either the PCRE error "internal error: code overflow" from pcre_compile(),
291     or a glibc crash with a message such as "pcretest: free(): invalid next
292     size (fast)". Examples of patterns that provoked this bug (shown in
293     pcretest format) are:
295     /(?-x: )/x
296     /(?x)(?-x: \s*#\s*)/
297     /((?i)[\x{c0}])/8
298     /(?i:[\x{c0}])/8
300     HOWEVER: Change 17 below makes this fix obsolete as the memory computation
301     is now done differently.
303     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
304     wrapper classes; (b) implement a new function in the C++ scanner that is
305     more efficient than the old way of doing things because it avoids levels of
306     recursion in the regex matching; (c) add a paragraph to the documentation
307     for the FullMatch() function.
309     6. The escape sequence \n was being treated as whatever was defined as
310     "newline". Not only was this contrary to the documentation, which states
311     that \n is character 10 (hex 0A), but it also went horribly wrong when
312     "newline" was defined as CRLF. This has been fixed.
314     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
315     was being set to -1 for the "end of line" case (supposedly a value that no
316     character can have). Though this value is never used (the check for end of
317     line is "zero bytes in current character"), it caused compiler complaints.
318     I've changed it to 0xffffffff.
320     8. In pcre_version.c, the version string was being built by a sequence of
321     C macros that, in the event of PCRE_PRERELEASE being defined as an empty
322     string (as it is for production releases) called a macro with an empty
323     argument. The C standard says the result of this is undefined. The gcc
324     compiler treats it as an empty string (which was what was wanted) but it is
325     reported that Visual C gives an error. The source has been hacked around to
326     avoid this problem.
328     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
329     builds of pcretest, and changed the call to _setmode() to use _O_BINARY
330     instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
331     of them did).
333     10. Originally, pcretest opened its input and output without "b"; then I was
334     told that "b" was needed in some environments, so it was added for release
335     5.0 to both the input and output. (It makes no difference on Unix-like
336     systems.) Later I was told that it is wrong for the input on Windows. I've
337     now abstracted the modes into two macros, to make it easier to fiddle with
338     them, and removed "b" from the input mode under Windows.
340     11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
342     12. Added -help and --help to pcretest as an official way of being reminded
343     of the options.
345     13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
346     and pcrecpp.cc because they annoy compilers at high warning levels.
348     14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
350     15. Fixed an occurrence of == in configure.ac that should have been = (shell
351     scripts are not C programs :-) and which was not noticed because it works
352     on Linux.
354     16. pcretest is supposed to handle any length of pattern and data line (as one
355     line or as a continued sequence of lines) by extending its input buffer if
356     necessary. This feature was broken for very long pattern lines, leading to
357     a string of junk being passed to pcre_compile() if the pattern was longer
358     than about 50K.
360     17. I have done a major re-factoring of the way pcre_compile() computes the
361     amount of memory needed for a compiled pattern. Previously, there was code
362     that made a preliminary scan of the pattern in order to do this. That was
363     OK when PCRE was new, but as the facilities have expanded, it has become
364     harder and harder to keep it in step with the real compile phase, and there
365     have been a number of bugs (see for example, 4 above). I have now found a
366     cunning way of running the real compile function in a "fake" mode that
367     enables it to compute how much memory it would need, while actually only
368     ever using a few hundred bytes of working memory and without too many
369     tests of the mode. This should make future maintenance and development
370     easier. A side effect of this work is that the limit of 200 on the nesting
371     depth of parentheses has been removed (though this was never a serious
372     limitation, I suspect). However, there is a downside: pcre_compile() now
373     runs more slowly than before (30% or more, depending on the pattern). I
374     hope this isn't a big issue. There is no effect on runtime performance.
376     18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
377     newline (only possible for the last line of a file) and it was a
378     pattern that set a locale (followed by /Lsomething), pcretest crashed.
380     19. Added additional timing features to pcretest. (1) The -tm option now times
381     matching only, not compiling. (2) Both -t and -tm can be followed, as a
382     separate command line item, by a number that specifies the number of
383     repeats to use when timing. The default is 50000; this gives better
384     precision, but takes uncomfortably long for very large patterns.
386     20. Extended pcre_study() to be more clever in cases where a branch of a
387     subpattern has no definite first character. For example, (a*|b*)[cd] would
388     previously give no result from pcre_study(). Now it recognizes that the
389     first character must be a, b, c, or d.
391     21. There was an incorrect error "recursive call could loop indefinitely" if
392     a subpattern (or the entire pattern) that was being tested for matching an
393     empty string contained only one non-empty item after a nested subpattern.
394     For example, the pattern (?>\x{100}*)\d(?R) provoked this error
395     incorrectly, because the \d was being skipped in the check.
397     22. The pcretest program now has a new pattern option /B and a command line
398     option -b, which is equivalent to adding /B to every pattern. This causes
399     it to show the compiled bytecode, without the additional information that
400     -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
401     is the same as /B/I).
403     23. A new optimization is now able automatically to treat some sequences such
404     as a*b as a*+b. More specifically, if something simple (such as a character
405     or a simple class like \d) has an unlimited quantifier, and is followed by
406     something that cannot possibly match the quantified thing, the quantifier
407     is automatically "possessified".
409     24. A recursive reference to a subpattern whose number was greater than 39
410     went wrong under certain circumstances in UTF-8 mode. This bug could also
411     have affected the operation of pcre_study().
413     25. Realized that a little bit of performance could be had by replacing
414     (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
416     26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
418     27. Possessive quantifiers such as a++ were previously implemented by turning
419     them into atomic groups such as ($>a+). Now they have their own opcodes,
420     which improves performance. This includes the automatically created ones
421     from 23 above.
423     28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
424     lookahead was broken if it was not anchored. PCRE was mistakenly expecting
425     the first matched character to be a colon. This applied both to named and
426     numbered groups.
428     29. The ucpinternal.h header file was missing its idempotency #ifdef.
430     30. I was sent a "project" file called libpcre.a.dev which I understand makes
431     building PCRE on Windows easier, so I have included it in the distribution.
433     31. There is now a check in pcretest against a ridiculously large number being
434     returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
435     loop, the loop is abandoned.
437     32. Forward references to subpatterns in conditions such as (?(2)...) where
438     subpattern 2 is defined later cause pcre_compile() to search forwards in
439     the pattern for the relevant set of parentheses. This search went wrong
440     when there were unescaped parentheses in a character class, parentheses
441     escaped with \Q...\E, or parentheses in a #-comment in /x mode.
443     33. "Subroutine" calls and backreferences were previously restricted to
444     referencing subpatterns earlier in the regex. This restriction has now
445     been removed.
447     34. Added a number of extra features that are going to be in Perl 5.10. On the
448     whole, these are just syntactic alternatives for features that PCRE had
449     previously implemented using the Python syntax or my own invention. The
450     other formats are all retained for compatibility.
452     (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
453     as (?P<name>...). The new forms, as well as being in Perl 5.10, are
454     also .NET compatible.
456     (b) A recursion or subroutine call to a named group can now be defined as
457     (?&name) as well as (?P>name).
459     (c) A backreference to a named group can now be defined as \k<name> or
460     \k'name' as well as (?P=name). The new forms, as well as being in Perl
461     5.10, are also .NET compatible.
463     (d) A conditional reference to a named group can now use the syntax
464     (?(<name>) or (?('name') as well as (?(name).
466     (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
467     groups (named and numbered) that are never evaluated inline, but can be
468     called as "subroutines" from elsewhere. In effect, the DEFINE condition
469     is always false. There may be only one alternative in such a group.
471     (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
472     as the simple (?(R). The condition is true only if the most recent
473     recursion is that of the given number or name. It does not search out
474     through the entire recursion stack.
476     (g) The escape \gN or \g{N} has been added, where N is a positive or
477     negative number, specifying an absolute or relative reference.
479     35. Tidied to get rid of some further signed/unsigned compiler warnings and
480     some "unreachable code" warnings.
482     36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
483     things, this adds five new scripts.
485     37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
486     There were also incompatibilities regarding the handling of \Q..\E inside
487     character classes, for example with patterns like [\Qa\E-\Qz\E] where the
488     hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
490     38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
491     matches an empty string, and forcibly breaks the loop. There were bugs in
492     this code in non-simple cases. For a pattern such as ^(a()*)* matched
493     against aaaa the result was just "a" rather than "aaaa", for example. Two
494     separate and independent bugs (that affected different cases) have been
495     fixed.
497     39. Refactored the code to abolish the use of different opcodes for small
498     capturing bracket numbers. This is a tidy that I avoided doing when I
499     removed the limit on the number of capturing brackets for 3.5 back in 2001.
500     The new approach is not only tidier, it makes it possible to reduce the
501     memory needed to fix the previous bug (38).
503     40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
504     sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
505     processing dot, circumflex, or dollar metacharacters, or #-comments in /x
506     mode.
508     41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
509     report.
511     42. Applied patch, originally from Ari Pollak, modified by Google, to allow
512     copy construction and assignment in the C++ wrapper.
514     43. Updated pcregrep to support "--newline=any". In the process, I fixed a
515     couple of bugs that could have given wrong results in the "--newline=crlf"
516     case.
518     44. Added a number of casts and did some reorganization of signed/unsigned int
519     variables following suggestions from Dair Grant. Also renamed the variable
520     "this" as "item" because it is a C++ keyword.
522     45. Arranged for dftables to add
524     #include "pcre_internal.h"
526     to pcre_chartables.c because without it, gcc 4.x may remove the array
527     definition from the final binary if PCRE is built into a static library and
528     dead code stripping is activated.
530     46. For an unanchored pattern, if a match attempt fails at the start of a
531     newline sequence, and the newline setting is CRLF or ANY, and the next two
532     characters are CRLF, advance by two characters instead of one.
535 nigel 91 Version 6.7 04-Jul-06
536     ---------------------
538     1. In order to handle tests when input lines are enormously long, pcretest has
539     been re-factored so that it automatically extends its buffers when
540     necessary. The code is crude, but this _is_ just a test program. The
541     default size has been increased from 32K to 50K.
543     2. The code in pcre_study() was using the value of the re argument before
544     testing it for NULL. (Of course, in any sensible call of the function, it
545     won't be NULL.)
547     3. The memmove() emulation function in pcre_internal.h, which is used on
548     systems that lack both memmove() and bcopy() - that is, hardly ever -
549     was missing a "static" storage class specifier.
551     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
552     containing an extended class (one that cannot be represented by a bitmap
553     because it contains high-valued characters or Unicode property items, e.g.
554     [\pZ]). Almost always one would set UTF-8 mode when processing such a
555     pattern, but PCRE should not loop if you do not (it no longer does).
556     [Detail: two cases were found: (a) a repeated subpattern containing an
557     extended class; (b) a recursive reference to a subpattern that followed a
558     previous extended class. It wasn't skipping over the extended class
559     correctly when UTF-8 mode was not set.]
561     5. A negated single-character class was not being recognized as fixed-length
562     in lookbehind assertions such as (?<=[^f]), leading to an incorrect
563     compile error "lookbehind assertion is not fixed length".
565     6. The RunPerlTest auxiliary script was showing an unexpected difference
566     between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
567     write a Perl script that can interpret lines of an input file either as
568     byte characters or as UTF-8, which is what "perltest" was being required to
569     do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
570     can't do is switch easily at run time between having the "use utf8;" pragma
571     or not. In the end, I fudged it by using the RunPerlTest script to insert
572     "use utf8;" explicitly for the UTF-8 tests.
574     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
575     the end of the subject string, contrary to the documentation and to what
576     Perl does. This was true of both matching functions. Now it matches only at
577     the start of the subject and immediately after *internal* newlines.
579     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
580     a pointer to an int instead of a pointer to an unsigned long int. This
581     caused problems on 64-bit systems.
583     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
584     instance of the 'standard' template library not being so standard".
586     10. There was no check on the number of named subpatterns nor the maximum
587     length of a subpattern name. The product of these values is used to compute
588     the size of the memory block for a compiled pattern. By supplying a very
589     long subpattern name and a large number of named subpatterns, the size
590     computation could be caused to overflow. This is now prevented by limiting
591     the length of names to 32 characters, and the number of named subpatterns
592     to 10,000.
594     11. Subpatterns that are repeated with specific counts have to be replicated in
595     the compiled pattern. The size of memory for this was computed from the
596     length of the subpattern and the repeat count. The latter is limited to
597     65535, but there was no limit on the former, meaning that integer overflow
598     could in principle occur. The compiled length of a repeated subpattern is
599     now limited to 30,000 bytes in order to prevent this.
601     12. Added the optional facility to have named substrings with the same name.
603     13. Added the ability to use a named substring as a condition, using the
604     Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
605     are numbers (not recommended). Forward references are permitted.
607     14. Added forward references in named backreferences (if you see what I mean).
609     15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
610     pattern could run off the end of the subject. For example, the pattern
611     "(?s)(.{1,5})"8 did this with the subject "ab".
613     16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
614     PCRE_CASELESS was set when matching characters that were quantified with ?
615     or *.
617     17. A character class other than a single negated character that had a minimum
618     but no maximum quantifier - for example [ab]{6,} - was not handled
619     correctly by pce_dfa_exec(). It would match only one character.
621     18. A valid (though odd) pattern that looked like a POSIX character
622     class but used an invalid character after [ (for example [[,abc,]]) caused
623     pcre_compile() to give the error "Failed: internal error: code overflow" or
624     in some cases to crash with a glibc free() error. This could even happen if
625     the pattern terminated after [[ but there just happened to be a sequence of
626     letters, a binary zero, and a closing ] in the memory that followed.
628     19. Perl's treatment of octal escapes in the range \400 to \777 has changed
629     over the years. Originally (before any Unicode support), just the bottom 8
630     bits were taken. Thus, for example, \500 really meant \100. Nowadays the
631     output from "man perlunicode" includes this:
633     The regular expression compiler produces polymorphic opcodes. That
634     is, the pattern adapts to the data and automatically switches to
635     the Unicode character scheme when presented with Unicode data--or
636     instead uses a traditional byte scheme when presented with byte
637     data.
639     Sadly, a wide octal escape does not cause a switch, and in a string with
640     no other multibyte characters, these octal escapes are treated as before.
641     Thus, in Perl, the pattern /\500/ actually matches \100 but the pattern
642     /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
643     Unicode string.
645     I have not perpetrated such confusion in PCRE. Up till now, it took just
646     the bottom 8 bits, as in old Perl. I have now made octal escapes with
647     values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
648     translate to the appropriate multibyte character.
650     29. Applied some refactoring to reduce the number of warnings from Microsoft
651     and Borland compilers. This has included removing the fudge introduced
652     seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
653     a warning about an unused variable.
655     21. PCRE has not included VT (character 0x0b) in the set of whitespace
656     characters since release 4.0, because Perl (from release 5.004) does not.
657     [Or at least, is documented not to: some releases seem to be in conflict
658     with the documentation.] However, when a pattern was studied with
659     pcre_study() and all its branches started with \s, PCRE still included VT
660     as a possible starting character. Of course, this did no harm; it just
661     caused an unnecessary match attempt.
663     22. Removed a now-redundant internal flag bit that recorded the fact that case
664     dependency changed within the pattern. This was once needed for "required
665     byte" processing, but is no longer used. This recovers a now-scarce options
666     bit. Also moved the least significant internal flag bit to the most-
667     significant bit of the word, which was not previously used (hangover from
668     the days when it was an int rather than a uint) to free up another bit for
669     the future.
671     23. Added support for CRLF line endings as well as CR and LF. As well as the
672     default being selectable at build time, it can now be changed at runtime
673     via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
674     specify that it is scanning data with non-default line endings.
676     24. Changed the definition of CXXLINK to make it agree with the definition of
677     LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
679     25. Applied Ian Taylor's patches to avoid using another stack frame for tail
680     recursions. This makes a big different to stack usage for some patterns.
682     26. If a subpattern containing a named recursion or subroutine reference such
683     as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
684     the space required for the compiled pattern went wrong and gave too small a
685     value. Depending on the environment, this could lead to "Failed: internal
686     error: code overflow at offset 49" or "glibc detected double free or
687     corruption" errors.
689     27. Applied patches from Google (a) to support the new newline modes and (b) to
690     advance over multibyte UTF-8 characters in GlobalReplace.
692     28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
693     difference for some implementation of PCRE in some Windows version.
695     29. Added some extra testing facilities to pcretest:
697     \q<number> in a data line sets the "match limit" value
698     \Q<number> in a data line sets the "match recursion limt" value
699     -S <number> sets the stack size, where <number> is in megabytes
701     The -S option isn't available for Windows.
704 nigel 89 Version 6.6 06-Feb-06
705     ---------------------
707     1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
708     in pcreposix.h. I have copied the definition from pcre.h.
710     2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
711     because pcre.h is no longer a built file.
713     3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
714     not normally included in the compiled code.
717 nigel 87 Version 6.5 01-Feb-06
718     ---------------------
720     1. When using the partial match feature with pcre_dfa_exec(), it was not
721     anchoring the second and subsequent partial matches at the new starting
722     point. This could lead to incorrect results. For example, with the pattern
723     /1234/, partially matching against "123" and then "a4" gave a match.
725     2. Changes to pcregrep:
727     (a) All non-match returns from pcre_exec() were being treated as failures
728     to match the line. Now, unless the error is PCRE_ERROR_NOMATCH, an
729     error message is output. Some extra information is given for the
731     probably the only errors that are likely to be caused by users (by
732     specifying a regex that has nested indefinite repeats, for instance).
733     If there are more than 20 of these errors, pcregrep is abandoned.
735     (b) A binary zero was treated as data while matching, but terminated the
736     output line if it was written out. This has been fixed: binary zeroes
737     are now no different to any other data bytes.
739     (c) Whichever of the LC_ALL or LC_CTYPE environment variables is set is
740     used to set a locale for matching. The --locale=xxxx long option has
741     been added (no short equivalent) to specify a locale explicitly on the
742     pcregrep command, overriding the environment variables.
744     (d) When -B was used with -n, some line numbers in the output were one less
745     than they should have been.
747     (e) Added the -o (--only-matching) option.
749     (f) If -A or -C was used with -c (count only), some lines of context were
750     accidentally printed for the final match.
752     (g) Added the -H (--with-filename) option.
754     (h) The combination of options -rh failed to suppress file names for files
755     that were found from directory arguments.
757     (i) Added the -D (--devices) and -d (--directories) options.
759     (j) Added the -F (--fixed-strings) option.
761     (k) Allow "-" to be used as a file name for -f as well as for a data file.
763     (l) Added the --colo(u)r option.
765     (m) Added Jeffrey Friedl's -S testing option, but within #ifdefs so that it
766     is not present by default.
768     3. A nasty bug was discovered in the handling of recursive patterns, that is,
769     items such as (?R) or (?1), when the recursion could match a number of
770     alternatives. If it matched one of the alternatives, but subsequently,
771     outside the recursion, there was a failure, the code tried to back up into
772     the recursion. However, because of the way PCRE is implemented, this is not
773     possible, and the result was an incorrect result from the match.
775     In order to prevent this happening, the specification of recursion has
776     been changed so that all such subpatterns are automatically treated as
777     atomic groups. Thus, for example, (?R) is treated as if it were (?>(?R)).
779     4. I had overlooked the fact that, in some locales, there are characters for
780     which isalpha() is true but neither isupper() nor islower() are true. In
781     the fr_FR locale, for instance, the \xAA and \xBA characters (ordmasculine
782     and ordfeminine) are like this. This affected the treatment of \w and \W
783     when they appeared in character classes, but not when they appeared outside
784     a character class. The bit map for "word" characters is now created
785     separately from the results of isalnum() instead of just taking it from the
786     upper, lower, and digit maps. (Plus the underscore character, of course.)
788     5. The above bug also affected the handling of POSIX character classes such as
789     [[:alpha:]] and [[:alnum:]]. These do not have their own bit maps in PCRE's
790     permanent tables. Instead, the bit maps for such a class were previously
791     created as the appropriate unions of the upper, lower, and digit bitmaps.
792     Now they are created by subtraction from the [[:word:]] class, which has
793     its own bitmap.
795     6. The [[:blank:]] character class matches horizontal, but not vertical space.
796     It is created by subtracting the vertical space characters (\x09, \x0a,
797     \x0b, \x0c) from the [[:space:]] bitmap. Previously, however, the
798     subtraction was done in the overall bitmap for a character class, meaning
799     that a class such as [\x0c[:blank:]] was incorrect because \x0c would not
800     be recognized. This bug has been fixed.
802     7. Patches from the folks at Google:
804     (a) pcrecpp.cc: "to handle a corner case that may or may not happen in
805     real life, but is still worth protecting against".
807     (b) pcrecpp.cc: "corrects a bug when negative radixes are used with
808     regular expressions".
810     (c) pcre_scanner.cc: avoid use of std::count() because not all systems
811     have it.
813     (d) Split off pcrecpparg.h from pcrecpp.h and had the former built by
814     "configure" and the latter not, in order to fix a problem somebody had
815     with compiling the Arg class on HP-UX.
817     (e) Improve the error-handling of the C++ wrapper a little bit.
819     (f) New tests for checking recursion limiting.
821     8. The pcre_memmove() function, which is used only if the environment does not
822     have a standard memmove() function (and is therefore rarely compiled),
823     contained two bugs: (a) use of int instead of size_t, and (b) it was not
824     returning a result (though PCRE never actually uses the result).
826     9. In the POSIX regexec() interface, if nmatch is specified as a ridiculously
827     large number - greater than INT_MAX/(3*sizeof(int)) - REG_ESPACE is
828     returned instead of calling malloc() with an overflowing number that would
829     most likely cause subsequent chaos.
831     10. The debugging option of pcretest was not showing the NO_AUTO_CAPTURE flag.
833     11. The POSIX flag REG_NOSUB is now supported. When a pattern that was compiled
834     with this option is matched, the nmatch and pmatch options of regexec() are
835     ignored.
837     12. Added REG_UTF8 to the POSIX interface. This is not defined by POSIX, but is
838     provided in case anyone wants to the the POSIX interface with UTF-8
839     strings.
841     13. Added CXXLDFLAGS to the Makefile parameters to provide settings only on the
842     C++ linking (needed for some HP-UX environments).
844     14. Avoid compiler warnings in get_ucpname() when compiled without UCP support
845     (unused parameter) and in the pcre_printint() function (omitted "default"
846     switch label when the default is to do nothing).
848     15. Added some code to make it possible, when PCRE is compiled as a C++
849     library, to replace subject pointers for pcre_exec() with a smart pointer
850     class, thus making it possible to process discontinuous strings.
852     16. The two macros PCRE_EXPORT and PCRE_DATA_SCOPE are confusing, and perform
853     much the same function. They were added by different people who were trying
854     to make PCRE easy to compile on non-Unix systems. It has been suggested
855     that PCRE_EXPORT be abolished now that there is more automatic apparatus
856     for compiling on Windows systems. I have therefore replaced it with
857     PCRE_DATA_SCOPE. This is set automatically for Windows; if not set it
858     defaults to "extern" for C or "extern C" for C++, which works fine on
859     Unix-like systems. It is now possible to override the value of PCRE_DATA_
860     SCOPE with something explicit in config.h. In addition:
862     (a) pcreposix.h still had just "extern" instead of either of these macros;
863     I have replaced it with PCRE_DATA_SCOPE.
865     (b) Functions such as _pcre_xclass(), which are internal to the library,
866     but external in the C sense, all had PCRE_EXPORT in their definitions.
867     This is apparently wrong for the Windows case, so I have removed it.
868     (It makes no difference on Unix-like systems.)
870     17. Added a new limit, MATCH_LIMIT_RECURSION, which limits the depth of nesting
871     of recursive calls to match(). This is different to MATCH_LIMIT because
872     that limits the total number of calls to match(), not all of which increase
873     the depth of recursion. Limiting the recursion depth limits the amount of
874     stack (or heap if NO_RECURSE is set) that is used. The default can be set
875     when PCRE is compiled, and changed at run time. A patch from Google adds
876     this functionality to the C++ interface.
878     18. Changes to the handling of Unicode character properties:
880     (a) Updated the table to Unicode 4.1.0.
882     (b) Recognize characters that are not in the table as "Cn" (undefined).
884     (c) I revised the way the table is implemented to a much improved format
885     which includes recognition of ranges. It now supports the ranges that
886     are defined in UnicodeData.txt, and it also amalgamates other
887     characters into ranges. This has reduced the number of entries in the
888     table from around 16,000 to around 3,000, thus reducing its size
889     considerably. I realized I did not need to use a tree structure after
890     all - a binary chop search is just as efficient. Having reduced the
891     number of entries, I extended their size from 6 bytes to 8 bytes to
892     allow for more data.
894     (d) Added support for Unicode script names via properties such as \p{Han}.
896     19. In UTF-8 mode, a backslash followed by a non-Ascii character was not
897     matching that character.
899     20. When matching a repeated Unicode property with a minimum greater than zero,
900     (for example \pL{2,}), PCRE could look past the end of the subject if it
901     reached it while seeking the minimum number of characters. This could
902     happen only if some of the characters were more than one byte long, because
903     there is a check for at least the minimum number of bytes.
905     21. Refactored the implementation of \p and \P so as to be more general, to
906     allow for more different types of property in future. This has changed the
907     compiled form incompatibly. Anybody with saved compiled patterns that use
908     \p or \P will have to recompile them.
910     22. Added "Any" and "L&" to the supported property types.
912     23. Recognize \x{...} as a code point specifier, even when not in UTF-8 mode,
913     but give a compile time error if the value is greater than 0xff.
915     24. The man pages for pcrepartial, pcreprecompile, and pcre_compile2 were
916     accidentally not being installed or uninstalled.
918     25. The pcre.h file was built from pcre.h.in, but the only changes that were
919     made were to insert the current release number. This seemed silly, because
920     it made things harder for people building PCRE on systems that don't run
921     "configure". I have turned pcre.h into a distributed file, no longer built
922     by "configure", with the version identification directly included. There is
923     no longer a pcre.h.in file.
925     However, this change necessitated a change to the pcre-config script as
926     well. It is built from pcre-config.in, and one of the substitutions was the
927     release number. I have updated configure.ac so that ./configure now finds
928     the release number by grepping pcre.h.
930     26. Added the ability to run the tests under valgrind.
933 nigel 85 Version 6.4 05-Sep-05
934     ---------------------
936     1. Change 6.0/10/(l) to pcregrep introduced a bug that caused separator lines
937     "--" to be printed when multiple files were scanned, even when none of the
938     -A, -B, or -C options were used. This is not compatible with Gnu grep, so I
939     consider it to be a bug, and have restored the previous behaviour.
941     2. A couple of code tidies to get rid of compiler warnings.
943     3. The pcretest program used to cheat by referring to symbols in the library
944     whose names begin with _pcre_. These are internal symbols that are not
945     really supposed to be visible externally, and in some environments it is
946     possible to suppress them. The cheating is now confined to including
947     certain files from the library's source, which is a bit cleaner.
949     4. Renamed pcre.in as pcre.h.in to go with pcrecpp.h.in; it also makes the
950     file's purpose clearer.
952     5. Reorganized pcre_ucp_findchar().
955 nigel 83 Version 6.3 15-Aug-05
956     ---------------------
958     1. The file libpcre.pc.in did not have general read permission in the tarball.
960     2. There were some problems when building without C++ support:
962     (a) If C++ support was not built, "make install" and "make test" still
963     tried to test it.
965     (b) There were problems when the value of CXX was explicitly set. Some
966     changes have been made to try to fix these, and ...
968     (c) --disable-cpp can now be used to explicitly disable C++ support.
970     (d) The use of @CPP_OBJ@ directly caused a blank line preceded by a
971     backslash in a target when C++ was disabled. This confuses some
972     versions of "make", apparently. Using an intermediate variable solves
973     this. (Same for CPP_LOBJ.)
975     3. $(LINK_FOR_BUILD) now includes $(CFLAGS_FOR_BUILD) and $(LINK)
976     (non-Windows) now includes $(CFLAGS) because these flags are sometimes
977     necessary on certain architectures.
979     4. Added a setting of -export-symbols-regex to the link command to remove
980     those symbols that are exported in the C sense, but actually are local
981     within the library, and not documented. Their names all begin with
982     "_pcre_". This is not a perfect job, because (a) we have to except some
983     symbols that pcretest ("illegally") uses, and (b) the facility isn't always
984     available (and never for static libraries). I have made a note to try to
985     find a way round (a) in the future.
988 nigel 81 Version 6.2 01-Aug-05
989     ---------------------
991     1. There was no test for integer overflow of quantifier values. A construction
992     such as {1111111111111111} would give undefined results. What is worse, if
993     a minimum quantifier for a parenthesized subpattern overflowed and became
994     negative, the calculation of the memory size went wrong. This could have
995     led to memory overwriting.
997     2. Building PCRE using VPATH was broken. Hopefully it is now fixed.
999     3. Added "b" to the 2nd argument of fopen() in dftables.c, for non-Unix-like
1000     operating environments where this matters.
1002     4. Applied Giuseppe Maxia's patch to add additional features for controlling
1003     PCRE options from within the C++ wrapper.
1005     5. Named capturing subpatterns were not being correctly counted when a pattern
1006     was compiled. This caused two problems: (a) If there were more than 100
1007     such subpatterns, the calculation of the memory needed for the whole
1008     compiled pattern went wrong, leading to an overflow error. (b) Numerical
1009     back references of the form \12, where the number was greater than 9, were
1010     not recognized as back references, even though there were sufficient
1011     previous subpatterns.
1013     6. Two minor patches to pcrecpp.cc in order to allow it to compile on older
1014     versions of gcc, e.g. 2.95.4.
1017 nigel 79 Version 6.1 21-Jun-05
1018     ---------------------
1020     1. There was one reference to the variable "posix" in pcretest.c that was not
1021     surrounded by "#if !defined NOPOSIX".
1023     2. Make it possible to compile pcretest without DFA support, UTF8 support, or
1024     the cross-check on the old pcre_info() function, for the benefit of the
1025     cut-down version of PCRE that is currently imported into Exim.
1027     3. A (silly) pattern starting with (?i)(?-i) caused an internal space
1028     allocation error. I've done the easy fix, which wastes 2 bytes for sensible
1029     patterns that start (?i) but I don't think that matters. The use of (?i) is
1030     just an example; this all applies to the other options as well.
1032     4. Since libtool seems to echo the compile commands it is issuing, the output
1033     from "make" can be reduced a bit by putting "@" in front of each libtool
1034     compile command.
1036     5. Patch from the folks at Google for configure.in to be a bit more thorough
1037     in checking for a suitable C++ installation before trying to compile the
1038     C++ stuff. This should fix a reported problem when a compiler was present,
1039     but no suitable headers.
1041     6. The man pages all had just "PCRE" as their title. I have changed them to
1042     be the relevant file name. I have also arranged that these names are
1043     retained in the file doc/pcre.txt, which is a concatenation in text format
1044     of all the man pages except the little individual ones for each function.
1046     7. The NON-UNIX-USE file had not been updated for the different set of source
1047     files that come with release 6. I also added a few comments about the C++
1048     wrapper.
1051 nigel 77 Version 6.0 07-Jun-05
1052     ---------------------
1054     1. Some minor internal re-organization to help with my DFA experiments.
1056     2. Some missing #ifdef SUPPORT_UCP conditionals in pcretest and printint that
1057     didn't matter for the library itself when fully configured, but did matter
1058     when compiling without UCP support, or within Exim, where the ucp files are
1059     not imported.
1061     3. Refactoring of the library code to split up the various functions into
1062     different source modules. The addition of the new DFA matching code (see
1063     below) to a single monolithic source would have made it really too
1064     unwieldy, quite apart from causing all the code to be include in a
1065     statically linked application, when only some functions are used. This is
1066     relevant even without the DFA addition now that patterns can be compiled in
1067     one application and matched in another.
1069     The downside of splitting up is that there have to be some external
1070     functions and data tables that are used internally in different modules of
1071     the library but which are not part of the API. These have all had their
1072     names changed to start with "_pcre_" so that they are unlikely to clash
1073     with other external names.
1075     4. Added an alternate matching function, pcre_dfa_exec(), which matches using
1076     a different (DFA) algorithm. Although it is slower than the original
1077     function, it does have some advantages for certain types of matching
1078     problem.
1080     5. Upgrades to pcretest in order to test the features of pcre_dfa_exec(),
1081     including restarting after a partial match.
1083     6. A patch for pcregrep that defines INVALID_FILE_ATTRIBUTES if it is not
1084     defined when compiling for Windows was sent to me. I have put it into the
1085     code, though I have no means of testing or verifying it.
1087     7. Added the pcre_refcount() auxiliary function.
1089     8. Added the PCRE_FIRSTLINE option. This constrains an unanchored pattern to
1090     match before or at the first newline in the subject string. In pcretest,
1091     the /f option on a pattern can be used to set this.
1093     9. A repeated \w when used in UTF-8 mode with characters greater than 256
1094     would behave wrongly. This has been present in PCRE since release 4.0.
1096     10. A number of changes to the pcregrep command:
1098     (a) Refactored how -x works; insert ^(...)$ instead of setting
1099     PCRE_ANCHORED and checking the length, in preparation for adding
1100     something similar for -w.
1102     (b) Added the -w (match as a word) option.
1104     (c) Refactored the way lines are read and buffered so as to have more
1105     than one at a time available.
1107     (d) Implemented a pcregrep test script.
1109     (e) Added the -M (multiline match) option. This allows patterns to match
1110     over several lines of the subject. The buffering ensures that at least
1111     8K, or the rest of the document (whichever is the shorter) is available
1112     for matching (and similarly the previous 8K for lookbehind assertions).
1114     (f) Changed the --help output so that it now says
1116     -w, --word-regex(p)
1118     instead of two lines, one with "regex" and the other with "regexp"
1119     because that confused at least one person since the short forms are the
1120     same. (This required a bit of code, as the output is generated
1121     automatically from a table. It wasn't just a text change.)
1123     (g) -- can be used to terminate pcregrep options if the next thing isn't an
1124     option but starts with a hyphen. Could be a pattern or a path name
1125     starting with a hyphen, for instance.
1127     (h) "-" can be given as a file name to represent stdin.
1129     (i) When file names are being printed, "(standard input)" is used for
1130     the standard input, for compatibility with GNU grep. Previously
1131     "<stdin>" was used.
1133     (j) The option --label=xxx can be used to supply a name to be used for
1134     stdin when file names are being printed. There is no short form.
1136     (k) Re-factored the options decoding logic because we are going to add
1137     two more options that take data. Such options can now be given in four
1138     different ways, e.g. "-fname", "-f name", "--file=name", "--file name".
1140     (l) Added the -A, -B, and -C options for requesting that lines of context
1141     around matches be printed.
1143     (m) Added the -L option to print the names of files that do not contain
1144     any matching lines, that is, the complement of -l.
1146     (n) The return code is 2 if any file cannot be opened, but pcregrep does
1147     continue to scan other files.
1149     (o) The -s option was incorrectly implemented. For compatibility with other
1150     greps, it now suppresses the error message for a non-existent or non-
1151     accessible file (but not the return code). There is a new option called
1152     -q that suppresses the output of matching lines, which was what -s was
1153     previously doing.
1155     (p) Added --include and --exclude options to specify files for inclusion
1156     and exclusion when recursing.
1158     11. The Makefile was not using the Autoconf-supported LDFLAGS macro properly.
1159     Hopefully, it now does.
1161     12. Missing cast in pcre_study().
1163     13. Added an "uninstall" target to the makefile.
1165     14. Replaced "extern" in the function prototypes in Makefile.in with
1166     "PCRE_DATA_SCOPE", which defaults to 'extern' or 'extern "C"' in the Unix
1167     world, but is set differently for Windows.
1169     15. Added a second compiling function called pcre_compile2(). The only
1170     difference is that it has an extra argument, which is a pointer to an
1171     integer error code. When there is a compile-time failure, this is set
1172     non-zero, in addition to the error test pointer being set to point to an
1173     error message. The new argument may be NULL if no error number is required
1174     (but then you may as well call pcre_compile(), which is now just a
1175     wrapper). This facility is provided because some applications need a
1176     numeric error indication, but it has also enabled me to tidy up the way
1177     compile-time errors are handled in the POSIX wrapper.
1179     16. Added VPATH=.libs to the makefile; this should help when building with one
1180     prefix path and installing with another. (Or so I'm told by someone who
1181     knows more about this stuff than I do.)
1183     17. Added a new option, REG_DOTALL, to the POSIX function regcomp(). This
1184     passes PCRE_DOTALL to the pcre_compile() function, making the "." character
1185     match everything, including newlines. This is not POSIX-compatible, but
1186     somebody wanted the feature. From pcretest it can be activated by using
1187     both the P and the s flags.
1189     18. AC_PROG_LIBTOOL appeared twice in Makefile.in. Removed one.
1191     19. libpcre.pc was being incorrectly installed as executable.
1193     20. A couple of places in pcretest check for end-of-line by looking for '\n';
1194     it now also looks for '\r' so that it will work unmodified on Windows.
1196     21. Added Google's contributed C++ wrapper to the distribution.
1198     22. Added some untidy missing memory free() calls in pcretest, to keep
1199     Electric Fence happy when testing.
1203 nigel 75 Version 5.0 13-Sep-04
1204     ---------------------
1206     1. Internal change: literal characters are no longer packed up into items
1207     containing multiple characters in a single byte-string. Each character
1208     is now matched using a separate opcode. However, there may be more than one
1209     byte in the character in UTF-8 mode.
1211     2. The pcre_callout_block structure has two new fields: pattern_position and
1212     next_item_length. These contain the offset in the pattern to the next match
1213     item, and its length, respectively.
1215     3. The PCRE_AUTO_CALLOUT option for pcre_compile() requests the automatic
1216     insertion of callouts before each pattern item. Added the /C option to
1217     pcretest to make use of this.
1219     4. On the advice of a Windows user, the lines
1221     #if defined(_WIN32) || defined(WIN32)
1222     _setmode( _fileno( stdout ), 0x8000 );
1223     #endif /* defined(_WIN32) || defined(WIN32) */
1225     have been added to the source of pcretest. This apparently does useful
1226     magic in relation to line terminators.
1228     5. Changed "r" and "w" in the calls to fopen() in pcretest to "rb" and "wb"
1229     for the benefit of those environments where the "b" makes a difference.
1231     6. The icc compiler has the same options as gcc, but "configure" doesn't seem
1232     to know about it. I have put a hack into configure.in that adds in code
1233     to set GCC=yes if CC=icc. This seems to end up at a point in the
1234     generated configure script that is early enough to affect the setting of
1235     compiler options, which is what is needed, but I have no means of testing
1236     whether it really works. (The user who reported this had patched the
1237     generated configure script, which of course I cannot do.)
1239     LATER: After change 22 below (new libtool files), the configure script
1240     seems to know about icc (and also ecc). Therefore, I have commented out
1241     this hack in configure.in.
1243     7. Added support for pkg-config (2 patches were sent in).
1245     8. Negated POSIX character classes that used a combination of internal tables
1246     were completely broken. These were [[:^alpha:]], [[:^alnum:]], and
1247     [[:^ascii]]. Typically, they would match almost any characters. The other
1248     POSIX classes were not broken in this way.
1250     9. Matching the pattern "\b.*?" against "ab cd", starting at offset 1, failed
1251     to find the match, as PCRE was deluded into thinking that the match had to
1252     start at the start point or following a newline. The same bug applied to
1253     patterns with negative forward assertions or any backward assertions
1254     preceding ".*" at the start, unless the pattern required a fixed first
1255     character. This was a failing pattern: "(?!.bcd).*". The bug is now fixed.
1257     10. In UTF-8 mode, when moving forwards in the subject after a failed match
1258     starting at the last subject character, bytes beyond the end of the subject
1259     string were read.
1261     11. Renamed the variable "class" as "classbits" to make life easier for C++
1262     users. (Previously there was a macro definition, but it apparently wasn't
1263     enough.)
1265     12. Added the new field "tables" to the extra data so that tables can be passed
1266     in at exec time, or the internal tables can be re-selected. This allows
1267     a compiled regex to be saved and re-used at a later time by a different
1268     program that might have everything at different addresses.
1270     13. Modified the pcre-config script so that, when run on Solaris, it shows a
1271     -R library as well as a -L library.
1273     14. The debugging options of pcretest (-d on the command line or D on a
1274     pattern) showed incorrect output for anything following an extended class
1275     that contained multibyte characters and which was followed by a quantifier.
1277     15. Added optional support for general category Unicode character properties
1278     via the \p, \P, and \X escapes. Unicode property support implies UTF-8
1279     support. It adds about 90K to the size of the library. The meanings of the
1280     inbuilt class escapes such as \d and \s have NOT been changed.
1282     16. Updated pcredemo.c to include calls to free() to release the memory for the
1283     compiled pattern.
1285     17. The generated file chartables.c was being created in the source directory
1286     instead of in the building directory. This caused the build to fail if the
1287     source directory was different from the building directory, and was
1288     read-only.
1290     18. Added some sample Win commands from Mark Tetrode into the NON-UNIX-USE
1291     file. No doubt somebody will tell me if they don't make sense... Also added
1292     Dan Mooney's comments about building on OpenVMS.
1294     19. Added support for partial matching via the PCRE_PARTIAL option for
1295     pcre_exec() and the \P data escape in pcretest.
1297     20. Extended pcretest with 3 new pattern features:
1299     (i) A pattern option of the form ">rest-of-line" causes pcretest to
1300     write the compiled pattern to the file whose name is "rest-of-line".
1301     This is a straight binary dump of the data, with the saved pointer to
1302     the character tables forced to be NULL. The study data, if any, is
1303     written too. After writing, pcretest reads a new pattern.
1305     (ii) If, instead of a pattern, "<rest-of-line" is given, pcretest reads a
1306     compiled pattern from the given file. There must not be any
1307     occurrences of "<" in the file name (pretty unlikely); if there are,
1308     pcretest will instead treat the initial "<" as a pattern delimiter.
1309     After reading in the pattern, pcretest goes on to read data lines as
1310     usual.
1312     (iii) The F pattern option causes pcretest to flip the bytes in the 32-bit
1313     and 16-bit fields in a compiled pattern, to simulate a pattern that
1314     was compiled on a host of opposite endianness.
1316     21. The pcre-exec() function can now cope with patterns that were compiled on
1317     hosts of opposite endianness, with this restriction:
1319     As for any compiled expression that is saved and used later, the tables
1320     pointer field cannot be preserved; the extra_data field in the arguments
1321     to pcre_exec() should be used to pass in a tables address if a value
1322     other than the default internal tables were used at compile time.
1324     22. Calling pcre_exec() with a negative value of the "ovecsize" parameter is
1325     now diagnosed as an error. Previously, most of the time, a negative number
1326     would have been treated as zero, but if in addition "ovector" was passed as
1327     NULL, a crash could occur.
1329     23. Updated the files ltmain.sh, config.sub, config.guess, and aclocal.m4 with
1330     new versions from the libtool 1.5 distribution (the last one is a copy of
1331     a file called libtool.m4). This seems to have fixed the need to patch
1332     "configure" to support Darwin 1.3 (which I used to do). However, I still
1333     had to patch ltmain.sh to ensure that ${SED} is set (it isn't on my
1334     workstation).
1336     24. Changed the PCRE licence to be the more standard "BSD" licence.
1339 nigel 73 Version 4.5 01-Dec-03
1340     ---------------------
1342     1. There has been some re-arrangement of the code for the match() function so
1343     that it can be compiled in a version that does not call itself recursively.
1344     Instead, it keeps those local variables that need separate instances for
1345     each "recursion" in a frame on the heap, and gets/frees frames whenever it
1346     needs to "recurse". Keeping track of where control must go is done by means
1347     of setjmp/longjmp. The whole thing is implemented by a set of macros that
1348     hide most of the details from the main code, and operates only if
1349     NO_RECURSE is defined while compiling pcre.c. If PCRE is built using the
1350     "configure" mechanism, "--disable-stack-for-recursion" turns on this way of
1351     operating.
1353     To make it easier for callers to provide specially tailored get/free
1354     functions for this usage, two new functions, pcre_stack_malloc, and
1355     pcre_stack_free, are used. They are always called in strict stacking order,
1356     and the size of block requested is always the same.
1358     The PCRE_CONFIG_STACKRECURSE info parameter can be used to find out whether
1359     PCRE has been compiled to use the stack or the heap for recursion. The
1360     -C option of pcretest uses this to show which version is compiled.
1362     A new data escape \S, is added to pcretest; it causes the amounts of store
1363     obtained and freed by both kinds of malloc/free at match time to be added
1364     to the output.
1366     2. Changed the locale test to use "fr_FR" instead of "fr" because that's
1367     what's available on my current Linux desktop machine.
1369     3. When matching a UTF-8 string, the test for a valid string at the start has
1370     been extended. If start_offset is not zero, PCRE now checks that it points
1371     to a byte that is the start of a UTF-8 character. If not, it returns
1372     PCRE_ERROR_BADUTF8_OFFSET (-11). Note: the whole string is still checked;
1373     this is necessary because there may be backward assertions in the pattern.
1374     When matching the same subject several times, it may save resources to use
1375     PCRE_NO_UTF8_CHECK on all but the first call if the string is long.
1377     4. The code for checking the validity of UTF-8 strings has been tightened so
1378     that it rejects (a) strings containing 0xfe or 0xff bytes and (b) strings
1379     containing "overlong sequences".
1381     5. Fixed a bug (appearing twice) that I could not find any way of exploiting!
1382     I had written "if ((digitab[*p++] && chtab_digit) == 0)" where the "&&"
1383     should have been "&", but it just so happened that all the cases this let
1384     through by mistake were picked up later in the function.
1386     6. I had used a variable called "isblank" - this is a C99 function, causing
1387     some compilers to warn. To avoid this, I renamed it (as "blankclass").
1389     7. Cosmetic: (a) only output another newline at the end of pcretest if it is
1390     prompting; (b) run "./pcretest /dev/null" at the start of the test script
1391     so the version is shown; (c) stop "make test" echoing "./RunTest".
1393     8. Added patches from David Burgess to enable PCRE to run on EBCDIC systems.
1395     9. The prototype for memmove() for systems that don't have it was using
1396     size_t, but the inclusion of the header that defines size_t was later. I've
1397     moved the #includes for the C headers earlier to avoid this.
1399     10. Added some adjustments to the code to make it easier to compiler on certain
1400     special systems:
1402     (a) Some "const" qualifiers were missing.
1403     (b) Added the macro EXPORT before all exported functions; by default this
1404     is defined to be empty.
1405     (c) Changed the dftables auxiliary program (that builds chartables.c) so
1406     that it reads its output file name as an argument instead of writing
1407     to the standard output and assuming this can be redirected.
1409     11. In UTF-8 mode, if a recursive reference (e.g. (?1)) followed a character
1410     class containing characters with values greater than 255, PCRE compilation
1411     went into a loop.
1413     12. A recursive reference to a subpattern that was within another subpattern
1414     that had a minimum quantifier of zero caused PCRE to crash. For example,
1415     (x(y(?2))z)? provoked this bug with a subject that got as far as the
1416     recursion. If the recursively-called subpattern itself had a zero repeat,
1417     that was OK.
1419     13. In pcretest, the buffer for reading a data line was set at 30K, but the
1420     buffer into which it was copied (for escape processing) was still set at
1421     1024, so long lines caused crashes.
1423     14. A pattern such as /[ab]{1,3}+/ failed to compile, giving the error
1424     "internal error: code overflow...". This applied to any character class
1425     that was followed by a possessive quantifier.
1427     15. Modified the Makefile to add libpcre.la as a prerequisite for
1428     libpcreposix.la because I was told this is needed for a parallel build to
1429     work.
1431     16. If a pattern that contained .* following optional items at the start was
1432     studied, the wrong optimizing data was generated, leading to matching
1433     errors. For example, studying /[ab]*.*c/ concluded, erroneously, that any
1434     matching string must start with a or b or c. The correct conclusion for
1435     this pattern is that a match can start with any character.
1438 nigel 71 Version 4.4 13-Aug-03
1439     ---------------------
1441     1. In UTF-8 mode, a character class containing characters with values between
1442     127 and 255 was not handled correctly if the compiled pattern was studied.
1443     In fixing this, I have also improved the studying algorithm for such
1444     classes (slightly).
1446     2. Three internal functions had redundant arguments passed to them. Removal
1447     might give a very teeny performance improvement.
1449     3. Documentation bug: the value of the capture_top field in a callout is *one
1450     more than* the number of the hightest numbered captured substring.
1452     4. The Makefile linked pcretest and pcregrep with -lpcre, which could result
1453     in incorrectly linking with a previously installed version. They now link
1454     explicitly with libpcre.la.
1456     5. configure.in no longer needs to recognize Cygwin specially.
1458     6. A problem in pcre.in for Windows platforms is fixed.
1460     7. If a pattern was successfully studied, and the -d (or /D) flag was given to
1461     pcretest, it used to include the size of the study block as part of its
1462     output. Unfortunately, the structure contains a field that has a different
1463     size on different hardware architectures. This meant that the tests that
1464     showed this size failed. As the block is currently always of a fixed size,
1465     this information isn't actually particularly useful in pcretest output, so
1466     I have just removed it.
1468     8. Three pre-processor statements accidentally did not start in column 1.
1469     Sadly, there are *still* compilers around that complain, even though
1470     standard C has not required this for well over a decade. Sigh.
1472     9. In pcretest, the code for checking callouts passed small integers in the
1473     callout_data field, which is a void * field. However, some picky compilers
1474     complained about the casts involved for this on 64-bit systems. Now
1475     pcretest passes the address of the small integer instead, which should get
1476     rid of the warnings.
1478     10. By default, when in UTF-8 mode, PCRE now checks for valid UTF-8 strings at
1479     both compile and run time, and gives an error if an invalid UTF-8 sequence
1480     is found. There is a option for disabling this check in cases where the
1481     string is known to be correct and/or the maximum performance is wanted.
1483     11. In response to a bug report, I changed one line in Makefile.in from
1485     -Wl,--out-implib,.libs/lib@WIN_PREFIX@pcreposix.dll.a \
1486     to
1487     -Wl,--out-implib,.libs/@WIN_PREFIX@libpcreposix.dll.a \
1489     to look similar to other lines, but I have no way of telling whether this
1490     is the right thing to do, as I do not use Windows. No doubt I'll get told
1491     if it's wrong...
1494 nigel 69 Version 4.3 21-May-03
1495     ---------------------
1497     1. Two instances of @WIN_PREFIX@ omitted from the Windows targets in the
1498     Makefile.
1500     2. Some refactoring to improve the quality of the code:
1502     (i) The utf8_table... variables are now declared "const".
1504     (ii) The code for \cx, which used the "case flipping" table to upper case
1505     lower case letters, now just substracts 32. This is ASCII-specific,
1506     but the whole concept of \cx is ASCII-specific, so it seems
1507     reasonable.
1509     (iii) PCRE was using its character types table to recognize decimal and
1510     hexadecimal digits in the pattern. This is silly, because it handles
1511     only 0-9, a-f, and A-F, but the character types table is locale-
1512     specific, which means strange things might happen. A private
1513     table is now used for this - though it costs 256 bytes, a table is
1514     much faster than multiple explicit tests. Of course, the standard
1515     character types table is still used for matching digits in subject
1516     strings against \d.
1518     (iv) Strictly, the identifier ESC_t is reserved by POSIX (all identifiers
1519     ending in _t are). So I've renamed it as ESC_tee.
1521     3. The first argument for regexec() in the POSIX wrapper should have been
1522     defined as "const".
1524     4. Changed pcretest to use malloc() for its buffers so that they can be
1525     Electric Fenced for debugging.
1527     5. There were several places in the code where, in UTF-8 mode, PCRE would try
1528     to read one or more bytes before the start of the subject string. Often this
1529     had no effect on PCRE's behaviour, but in some circumstances it could
1530     provoke a segmentation fault.
1532     6. A lookbehind at the start of a pattern in UTF-8 mode could also cause PCRE
1533     to try to read one or more bytes before the start of the subject string.
1535     7. A lookbehind in a pattern matched in non-UTF-8 mode on a PCRE compiled with
1536     UTF-8 support could misbehave in various ways if the subject string
1537     contained bytes with the 0x80 bit set and the 0x40 bit unset in a lookbehind
1538     area. (PCRE was not checking for the UTF-8 mode flag, and trying to move
1539     back over UTF-8 characters.)
1542 nigel 67 Version 4.2 14-Apr-03
1543     ---------------------
1545     1. Typo "#if SUPPORT_UTF8" instead of "#ifdef SUPPORT_UTF8" fixed.
1547     2. Changes to the building process, supplied by Ronald Landheer-Cieslak
1548     [ON_WINDOWS]: new variable, "#" on non-Windows platforms
1549     [NOT_ON_WINDOWS]: new variable, "#" on Windows platforms
1550     [WIN_PREFIX]: new variable, "cyg" for Cygwin
1551     * Makefile.in: use autoconf substitution for OBJEXT, EXEEXT, BUILD_OBJEXT
1552     and BUILD_EXEEXT
1553     Note: automatic setting of the BUILD variables is not yet working
1554     set CPPFLAGS and BUILD_CPPFLAGS (but don't use yet) - should be used at
1555     compile-time but not at link-time
1556     [LINK]: use for linking executables only
1557     make different versions for Windows and non-Windows
1558     [LINKLIB]: new variable, copy of UNIX-style LINK, used for linking
1559     libraries
1560     [LINK_FOR_BUILD]: new variable
1561     [OBJEXT]: use throughout
1562     [EXEEXT]: use throughout
1563     <winshared>: new target
1564     <wininstall>: new target
1565     <dftables.o>: use native compiler
1566     <dftables>: use native linker
1567     <install>: handle Windows platform correctly
1568     <clean>: ditto
1569     <check>: ditto
1570     copy DLL to top builddir before testing
1572     As part of these changes, -no-undefined was removed again. This was reported
1573     to give trouble on HP-UX 11.0, so getting rid of it seems like a good idea
1574     in any case.
1576     3. Some tidies to get rid of compiler warnings:
1578     . In the match_data structure, match_limit was an unsigned long int, whereas
1579     match_call_count was an int. I've made them both unsigned long ints.
1581     . In pcretest the fact that a const uschar * doesn't automatically cast to
1582     a void * provoked a warning.
1584     . Turning on some more compiler warnings threw up some "shadow" variables
1585     and a few more missing casts.
1587     4. If PCRE was complied with UTF-8 support, but called without the PCRE_UTF8
1588     option, a class that contained a single character with a value between 128
1589     and 255 (e.g. /[\xFF]/) caused PCRE to crash.
1591     5. If PCRE was compiled with UTF-8 support, but called without the PCRE_UTF8
1592     option, a class that contained several characters, but with at least one
1593     whose value was between 128 and 255 caused PCRE to crash.
1596 nigel 65 Version 4.1 12-Mar-03
1597     ---------------------
1598 nigel 63
1599 nigel 65 1. Compiling with gcc -pedantic found a couple of places where casts were
1600     needed, and a string in dftables.c that was longer than standard compilers are
1601     required to support.
1603     2. Compiling with Sun's compiler found a few more places where the code could
1604     be tidied up in order to avoid warnings.
1606     3. The variables for cross-compiling were called HOST_CC and HOST_CFLAGS; the
1607     first of these names is deprecated in the latest Autoconf in favour of the name
1608     CC_FOR_BUILD, because "host" is typically used to mean the system on which the
1609     compiled code will be run. I can't find a reference for HOST_CFLAGS, but by
1610     analogy I have changed it to CFLAGS_FOR_BUILD.
1612     4. Added -no-undefined to the linking command in the Makefile, because this is
1613     apparently helpful for Windows. To make it work, also added "-L. -lpcre" to the
1614     linking step for the pcreposix library.
1616     5. PCRE was failing to diagnose the case of two named groups with the same
1617     name.
1619     6. A problem with one of PCRE's optimizations was discovered. PCRE remembers a
1620     literal character that is needed in the subject for a match, and scans along to
1621     ensure that it is present before embarking on the full matching process. This
1622     saves time in cases of nested unlimited repeats that are never going to match.
1623     Problem: the scan can take a lot of time if the subject is very long (e.g.
1624     megabytes), thus penalizing straightforward matches. It is now done only if the
1625     amount of subject to be scanned is less than 1000 bytes.
1627     7. A lesser problem with the same optimization is that it was recording the
1628     first character of an anchored pattern as "needed", thus provoking a search
1629     right along the subject, even when the first match of the pattern was going to
1630     fail. The "needed" character is now not set for anchored patterns, unless it
1631     follows something in the pattern that is of non-fixed length. Thus, it still
1632     fulfils its original purpose of finding quick non-matches in cases of nested
1633     unlimited repeats, but isn't used for simple anchored patterns such as /^abc/.
1636     Version 4.0 17-Feb-03
1637     ---------------------
1639 nigel 63 1. If a comment in an extended regex that started immediately after a meta-item
1640     extended to the end of string, PCRE compiled incorrect data. This could lead to
1641     all kinds of weird effects. Example: /#/ was bad; /()#/ was bad; /a#/ was not.
1643     2. Moved to autoconf 2.53 and libtool 1.4.2.
1645     3. Perl 5.8 no longer needs "use utf8" for doing UTF-8 things. Consequently,
1646     the special perltest8 script is no longer needed - all the tests can be run
1647     from a single perltest script.
1649     4. From 5.004, Perl has not included the VT character (0x0b) in the set defined
1650     by \s. It has now been removed in PCRE. This means it isn't recognized as
1651     whitespace in /x regexes too, which is the same as Perl. Note that the POSIX
1652     class [:space:] *does* include VT, thereby creating a mess.
1654     5. Added the class [:blank:] (a GNU extension from Perl 5.8) to match only
1655     space and tab.
1657     6. Perl 5.005 was a long time ago. It's time to amalgamate the tests that use
1658     its new features into the main test script, reducing the number of scripts.
1660     7. Perl 5.8 has changed the meaning of patterns like /a(?i)b/. Earlier versions
1661     were backward compatible, and made the (?i) apply to the whole pattern, as if
1662     /i were given. Now it behaves more logically, and applies the option setting
1663     only to what follows. PCRE has been changed to follow suit. However, if it
1664     finds options settings right at the start of the pattern, it extracts them into
1665     the global options, as before. Thus, they show up in the info data.
1667     8. Added support for the \Q...\E escape sequence. Characters in between are
1668     treated as literals. This is slightly different from Perl in that $ and @ are
1669     also handled as literals inside the quotes. In Perl, they will cause variable
1670     interpolation. Note the following examples:
1672     Pattern PCRE matches Perl matches
1674     \Qabc$xyz\E abc$xyz abc followed by the contents of $xyz
1675     \Qabc\$xyz\E abc\$xyz abc\$xyz
1676     \Qabc\E\$\Qxyz\E abc$xyz abc$xyz
1678     For compatibility with Perl, \Q...\E sequences are recognized inside character
1679     classes as well as outside them.
1681     9. Re-organized 3 code statements in pcretest to avoid "overflow in
1682     floating-point constant arithmetic" warnings from a Microsoft compiler. Added a
1683     (size_t) cast to one statement in pcretest and one in pcreposix to avoid
1684     signed/unsigned warnings.
1686     10. SunOS4 doesn't have strtoul(). This was used only for unpicking the -o
1687     option for pcretest, so I've replaced it by a simple function that does just
1688     that job.
1690     11. pcregrep was ending with code 0 instead of 2 for the commands "pcregrep" or
1691     "pcregrep -".
1693     12. Added "possessive quantifiers" ?+, *+, ++, and {,}+ which come from Sun's
1694     Java package. This provides some syntactic sugar for simple cases of what my
1695     documentation calls "once-only subpatterns". A pattern such as x*+ is the same
1696     as (?>x*). In other words, if what is inside (?>...) is just a single repeated
1697     item, you can use this simplified notation. Note that only makes sense with
1698     greedy quantifiers. Consequently, the use of the possessive quantifier forces
1699     greediness, whatever the setting of the PCRE_UNGREEDY option.
1701     13. A change of greediness default within a pattern was not taking effect at
1702     the current level for patterns like /(b+(?U)a+)/. It did apply to parenthesized
1703     subpatterns that followed. Patterns like /b+(?U)a+/ worked because the option
1704     was abstracted outside.
1706     14. PCRE now supports the \G assertion. It is true when the current matching
1707     position is at the start point of the match. This differs from \A when the
1708     starting offset is non-zero. Used with the /g option of pcretest (or similar
1709     code), it works in the same way as it does for Perl's /g option. If all
1710     alternatives of a regex begin with \G, the expression is anchored to the start
1711     match position, and the "anchored" flag is set in the compiled expression.
1713     15. Some bugs concerning the handling of certain option changes within patterns
1714     have been fixed. These applied to options other than (?ims). For example,
1715     "a(?x: b c )d" did not match "XabcdY" but did match "Xa b c dY". It should have
1716     been the other way round. Some of this was related to change 7 above.
1718     16. PCRE now gives errors for /[.x.]/ and /[=x=]/ as unsupported POSIX
1719     features, as Perl does. Previously, PCRE gave the warnings only for /[[.x.]]/
1720     and /[[=x=]]/. PCRE now also gives an error for /[:name:]/ because it supports
1721     POSIX classes only within a class (e.g. /[[:alpha:]]/).
1723     17. Added support for Perl's \C escape. This matches one byte, even in UTF8
1724     mode. Unlike ".", it always matches newline, whatever the setting of
1725     PCRE_DOTALL. However, PCRE does not permit \C to appear in lookbehind
1726     assertions. Perl allows it, but it doesn't (in general) work because it can't
1727     calculate the length of the lookbehind. At least, that's the case for Perl
1728     5.8.0 - I've been told they are going to document that it doesn't work in
1729     future.
1731     18. Added an error diagnosis for escapes that PCRE does not support: these are
1732     \L, \l, \N, \P, \p, \U, \u, and \X.
1734     19. Although correctly diagnosing a missing ']' in a character class, PCRE was
1735     reading past the end of the pattern in cases such as /[abcd/.
1737     20. PCRE was getting more memory than necessary for patterns with classes that
1738     contained both POSIX named classes and other characters, e.g. /[[:space:]abc/.
1740     21. Added some code, conditional on #ifdef VPCOMPAT, to make life easier for
1741     compiling PCRE for use with Virtual Pascal.
1743     22. Small fix to the Makefile to make it work properly if the build is done
1744     outside the source tree.
1746     23. Added a new extension: a condition to go with recursion. If a conditional
1747     subpattern starts with (?(R) the "true" branch is used if recursion has
1748     happened, whereas the "false" branch is used only at the top level.
1750     24. When there was a very long string of literal characters (over 255 bytes
1751     without UTF support, over 250 bytes with UTF support), the computation of how
1752     much memory was required could be incorrect, leading to segfaults or other
1753     strange effects.
1755     25. PCRE was incorrectly assuming anchoring (either to start of subject or to
1756     start of line for a non-DOTALL pattern) when a pattern started with (.*) and
1757     there was a subsequent back reference to those brackets. This meant that, for
1758     example, /(.*)\d+\1/ failed to match "abc123bc". Unfortunately, it isn't
1759     possible to check for precisely this case. All we can do is abandon the
1760     optimization if .* occurs inside capturing brackets when there are any back
1761     references whatsoever. (See below for a better fix that came later.)
1763     26. The handling of the optimization for finding the first character of a
1764     non-anchored pattern, and for finding a character that is required later in the
1765     match were failing in some cases. This didn't break the matching; it just
1766     failed to optimize when it could. The way this is done has been re-implemented.
1768     27. Fixed typo in error message for invalid (?R item (it said "(?p").
1770     28. Added a new feature that provides some of the functionality that Perl
1771     provides with (?{...}). The facility is termed a "callout". The way it is done
1772     in PCRE is for the caller to provide an optional function, by setting
1773     pcre_callout to its entry point. Like pcre_malloc and pcre_free, this is a
1774     global variable. By default it is unset, which disables all calling out. To get
1775     the function called, the regex must include (?C) at appropriate points. This
1776     is, in fact, equivalent to (?C0), and any number <= 255 may be given with (?C).
1777     This provides a means of identifying different callout points. When PCRE
1778     reaches such a point in the regex, if pcre_callout has been set, the external
1779     function is called. It is provided with data in a structure called
1780     pcre_callout_block, which is defined in pcre.h. If the function returns 0,
1781     matching continues; if it returns a non-zero value, the match at the current
1782     point fails. However, backtracking will occur if possible. [This was changed
1783     later and other features added - see item 49 below.]
1785     29. pcretest is upgraded to test the callout functionality. It provides a
1786     callout function that displays information. By default, it shows the start of
1787     the match and the current position in the text. There are some new data escapes
1788     to vary what happens:
1790     \C+ in addition, show current contents of captured substrings
1791     \C- do not supply a callout function
1792     \C!n return 1 when callout number n is reached
1793     \C!n!m return 1 when callout number n is reached for the mth time
1795     30. If pcregrep was called with the -l option and just a single file name, it
1796     output "<stdin>" if a match was found, instead of the file name.
1798     31. Improve the efficiency of the POSIX API to PCRE. If the number of capturing
1799     slots is less than POSIX_MALLOC_THRESHOLD, use a block on the stack to pass to
1800     pcre_exec(). This saves a malloc/free per call. The default value of
1801     POSIX_MALLOC_THRESHOLD is 10; it can be changed by --with-posix-malloc-threshold
1802     when configuring.
1804     32. The default maximum size of a compiled pattern is 64K. There have been a
1805     few cases of people hitting this limit. The code now uses macros to handle the
1806     storing of links as offsets within the compiled pattern. It defaults to 2-byte
1807     links, but this can be changed to 3 or 4 bytes by --with-link-size when
1808     configuring. Tests 2 and 5 work only with 2-byte links because they output
1809     debugging information about compiled patterns.
1811     33. Internal code re-arrangements:
1813     (a) Moved the debugging function for printing out a compiled regex into
1814     its own source file (printint.c) and used #include to pull it into
1815     pcretest.c and, when DEBUG is defined, into pcre.c, instead of having two
1816     separate copies.
1818     (b) Defined the list of op-code names for debugging as a macro in
1819     internal.h so that it is next to the definition of the opcodes.
1821     (c) Defined a table of op-code lengths for simpler skipping along compiled
1822     code. This is again a macro in internal.h so that it is next to the
1823     definition of the opcodes.
1825     34. Added support for recursive calls to individual subpatterns, along the
1826     lines of Robin Houston's patch (but implemented somewhat differently).
1828     35. Further mods to the Makefile to help Win32. Also, added code to pcregrep to
1829     allow it to read and process whole directories in Win32. This code was
1830     contributed by Lionel Fourquaux; it has not been tested by me.
1832     36. Added support for named subpatterns. The Python syntax (?P<name>...) is
1833     used to name a group. Names consist of alphanumerics and underscores, and must
1834     be unique. Back references use the syntax (?P=name) and recursive calls use
1835     (?P>name) which is a PCRE extension to the Python extension. Groups still have
1836     numbers. The function pcre_fullinfo() can be used after compilation to extract
1837     a name/number map. There are three relevant calls:
1839     PCRE_INFO_NAMEENTRYSIZE yields the size of each entry in the map
1840     PCRE_INFO_NAMECOUNT yields the number of entries
1841     PCRE_INFO_NAMETABLE yields a pointer to the map.
1843     The map is a vector of fixed-size entries. The size of each entry depends on
1844     the length of the longest name used. The first two bytes of each entry are the
1845     group number, most significant byte first. There follows the corresponding
1846     name, zero terminated. The names are in alphabetical order.
1848     37. Make the maximum literal string in the compiled code 250 for the non-UTF-8
1849     case instead of 255. Making it the same both with and without UTF-8 support
1850     means that the same test output works with both.
1852     38. There was a case of malloc(0) in the POSIX testing code in pcretest. Avoid
1853     calling malloc() with a zero argument.
1855     39. Change 25 above had to resort to a heavy-handed test for the .* anchoring
1856     optimization. I've improved things by keeping a bitmap of backreferences with
1857     numbers 1-31 so that if .* occurs inside capturing brackets that are not in
1858     fact referenced, the optimization can be applied. It is unlikely that a
1859     relevant occurrence of .* (i.e. one which might indicate anchoring or forcing
1860     the match to follow \n) will appear inside brackets with a number greater than
1861     31, but if it does, any back reference > 31 suppresses the optimization.
1863     40. Added a new compile-time option PCRE_NO_AUTO_CAPTURE. This has the effect
1864     of disabling numbered capturing parentheses. Any opening parenthesis that is
1865     not followed by ? behaves as if it were followed by ?: but named parentheses
1866     can still be used for capturing (and they will acquire numbers in the usual
1867     way).
1869     41. Redesigned the return codes from the match() function into yes/no/error so
1870     that errors can be passed back from deep inside the nested calls. A malloc
1871     failure while inside a recursive subpattern call now causes the
1872     PCRE_ERROR_NOMEMORY return instead of quietly going wrong.
1874     42. It is now possible to set a limit on the number of times the match()
1875     function is called in a call to pcre_exec(). This facility makes it possible to
1876     limit the amount of recursion and backtracking, though not in a directly
1877     obvious way, because the match() function is used in a number of different
1878     circumstances. The count starts from zero for each position in the subject
1879     string (for non-anchored patterns). The default limit is, for compatibility, a
1880     large number, namely 10 000 000. You can change this in two ways:
1882     (a) When configuring PCRE before making, you can use --with-match-limit=n
1883     to set a default value for the compiled library.
1885     (b) For each call to pcre_exec(), you can pass a pcre_extra block in which
1886     a different value is set. See 45 below.
1888     If the limit is exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT.
1890     43. Added a new function pcre_config(int, void *) to enable run-time extraction
1891     of things that can be changed at compile time. The first argument specifies
1892     what is wanted and the second points to where the information is to be placed.
1893     The current list of available information is:
1897     The output is an integer that is set to one if UTF-8 support is available;
1898     otherwise it is set to zero.
1902     The output is an integer that it set to the value of the code that is used for
1903     newline. It is either LF (10) or CR (13).
1907     The output is an integer that contains the number of bytes used for internal
1908     linkage in compiled expressions. The value is 2, 3, or 4. See item 32 above.
1912     The output is an integer that contains the threshold above which the POSIX
1913     interface uses malloc() for output vectors. See item 31 above.
1917     The output is an unsigned integer that contains the default limit of the number
1918     of match() calls in a pcre_exec() execution. See 42 above.
1920     44. pcretest has been upgraded by the addition of the -C option. This causes it
1921     to extract all the available output from the new pcre_config() function, and to
1922     output it. The program then exits immediately.
1924     45. A need has arisen to pass over additional data with calls to pcre_exec() in
1925     order to support additional features. One way would have been to define
1926     pcre_exec2() (for example) with extra arguments, but this would not have been
1927     extensible, and would also have required all calls to the original function to
1928     be mapped to the new one. Instead, I have chosen to extend the mechanism that
1929     is used for passing in "extra" data from pcre_study().
1931     The pcre_extra structure is now exposed and defined in pcre.h. It currently
1932     contains the following fields:
1934     flags a bitmap indicating which of the following fields are set
1935     study_data opaque data from pcre_study()
1936     match_limit a way of specifying a limit on match() calls for a specific
1937     call to pcre_exec()
1938     callout_data data for callouts (see 49 below)
1940     The flag bits are also defined in pcre.h, and are
1946     The pcre_study() function now returns one of these new pcre_extra blocks, with
1947     the actual study data pointed to by the study_data field, and the
1948     PCRE_EXTRA_STUDY_DATA flag set. This can be passed directly to pcre_exec() as
1949     before. That is, this change is entirely upwards-compatible and requires no
1950     change to existing code.
1952     If you want to pass in additional data to pcre_exec(), you can either place it
1953     in a pcre_extra block provided by pcre_study(), or create your own pcre_extra
1954     block.
1956     46. pcretest has been extended to test the PCRE_EXTRA_MATCH_LIMIT feature. If a
1957     data string contains the escape sequence \M, pcretest calls pcre_exec() several
1958     times with different match limits, until it finds the minimum value needed for
1959     pcre_exec() to complete. The value is then output. This can be instructive; for
1960     most simple matches the number is quite small, but for pathological cases it
1961     gets very large very quickly.
1963     47. There's a new option for pcre_fullinfo() called PCRE_INFO_STUDYSIZE. It
1964     returns the size of the data block pointed to by the study_data field in a
1965     pcre_extra block, that is, the value that was passed as the argument to
1966     pcre_malloc() when PCRE was getting memory in which to place the information
1967     created by pcre_study(). The fourth argument should point to a size_t variable.
1968     pcretest has been extended so that this information is shown after a successful
1969     pcre_study() call when information about the compiled regex is being displayed.
1971     48. Cosmetic change to Makefile: there's no need to have / after $(DESTDIR)
1972     because what follows is always an absolute path. (Later: it turns out that this
1973     is more than cosmetic for MinGW, because it doesn't like empty path
1974     components.)
1976     49. Some changes have been made to the callout feature (see 28 above):
1978     (i) A callout function now has three choices for what it returns:
1980     0 => success, carry on matching
1981     > 0 => failure at this point, but backtrack if possible
1982     < 0 => serious error, return this value from pcre_exec()
1984     Negative values should normally be chosen from the set of PCRE_ERROR_xxx
1985     values. In particular, returning PCRE_ERROR_NOMATCH forces a standard
1986     "match failed" error. The error number PCRE_ERROR_CALLOUT is reserved for
1987     use by callout functions. It will never be used by PCRE itself.
1989     (ii) The pcre_extra structure (see 45 above) has a void * field called
1990     callout_data, with corresponding flag bit PCRE_EXTRA_CALLOUT_DATA. The
1991     pcre_callout_block structure has a field of the same name. The contents of
1992     the field passed in the pcre_extra structure are passed to the callout
1993     function in the corresponding field in the callout block. This makes it
1994     easier to use the same callout-containing regex from multiple threads. For
1995     testing, the pcretest program has a new data escape
1997     \C*n pass the number n (may be negative) as callout_data
1999     If the callout function in pcretest receives a non-zero value as
2000     callout_data, it returns that value.
2002     50. Makefile wasn't handling CFLAGS properly when compiling dftables. Also,
2003     there were some redundant $(CFLAGS) in commands that are now specified as
2004     $(LINK), which already includes $(CFLAGS).
2006     51. Extensions to UTF-8 support are listed below. These all apply when (a) PCRE
2007     has been compiled with UTF-8 support *and* pcre_compile() has been compiled
2008     with the PCRE_UTF8 flag. Patterns that are compiled without that flag assume
2009     one-byte characters throughout. Note that case-insensitive matching applies
2010     only to characters whose values are less than 256. PCRE doesn't support the
2011     notion of cases for higher-valued characters.
2013     (i) A character class whose characters are all within 0-255 is handled as
2014     a bit map, and the map is inverted for negative classes. Previously, a
2015     character > 255 always failed to match such a class; however it should
2016     match if the class was a negative one (e.g. [^ab]). This has been fixed.
2018     (ii) A negated character class with a single character < 255 is coded as
2019     "not this character" (OP_NOT). This wasn't working properly when the test
2020     character was multibyte, either singly or repeated.
2022     (iii) Repeats of multibyte characters are now handled correctly in UTF-8
2023     mode, for example: \x{100}{2,3}.
2025     (iv) The character escapes \b, \B, \d, \D, \s, \S, \w, and \W (either
2026     singly or repeated) now correctly test multibyte characters. However,
2027     PCRE doesn't recognize any characters with values greater than 255 as
2028     digits, spaces, or word characters. Such characters always match \D, \S,
2029     and \W, and never match \d, \s, or \w.
2031     (v) Classes may now contain characters and character ranges with values
2032     greater than 255. For example: [ab\x{100}-\x{400}].
2034     (vi) pcregrep now has a --utf-8 option (synonym -u) which makes it call
2035     PCRE in UTF-8 mode.
2037     52. The info request value PCRE_INFO_FIRSTCHAR has been renamed
2038     PCRE_INFO_FIRSTBYTE because it is a byte value. However, the old name is
2039     retained for backwards compatibility. (Note that LASTLITERAL is also a byte
2040     value.)
2042     53. The single man page has become too large. I have therefore split it up into
2043     a number of separate man pages. These also give rise to individual HTML pages;
2044     these are now put in a separate directory, and there is an index.html page that
2045     lists them all. Some hyperlinking between the pages has been installed.
2047     54. Added convenience functions for handling named capturing parentheses.
2049     55. Unknown escapes inside character classes (e.g. [\M]) and escapes that
2050     aren't interpreted therein (e.g. [\C]) are literals in Perl. This is now also
2051     true in PCRE, except when the PCRE_EXTENDED option is set, in which case they
2052     are faulted.
2054     56. Introduced HOST_CC and HOST_CFLAGS which can be set in the environment when
2055     calling configure. These values are used when compiling the dftables.c program
2056     which is run to generate the source of the default character tables. They
2057     default to the values of CC and CFLAGS. If you are cross-compiling PCRE,
2058     you will need to set these values.
2060     57. Updated the building process for Windows DLL, as provided by Fred Cox.
2063     Version 3.9 02-Jan-02
2064 nigel 61 ---------------------
2066     1. A bit of extraneous text had somehow crept into the pcregrep documentation.
2068     2. If --disable-static was given, the building process failed when trying to
2069     build pcretest and pcregrep. (For some reason it was using libtool to compile
2070     them, which is not right, as they aren't part of the library.)
2073 nigel 59 Version 3.8 18-Dec-01
2074     ---------------------
2076     1. The experimental UTF-8 code was completely screwed up. It was packing the
2077     bytes in the wrong order. How dumb can you get?
2080 nigel 57 Version 3.7 29-Oct-01
2081     ---------------------
2083     1. In updating pcretest to check change 1 of version 3.6, I screwed up.
2084     This caused pcretest, when used on the test data, to segfault. Unfortunately,
2085     this didn't happen under Solaris 8, where I normally test things.
2087 nigel 59 2. The Makefile had to be changed to make it work on BSD systems, where 'make'
2088     doesn't seem to recognize that ./xxx and xxx are the same file. (This entry
2089     isn't in ChangeLog distributed with 3.7 because I forgot when I hastily made
2090     this fix an hour or so after the initial 3.7 release.)
2091 nigel 57
2092 nigel 59
2093 nigel 55 Version 3.6 23-Oct-01
2094     ---------------------
2096     1. Crashed with /(sens|respons)e and \1ibility/ and "sense and sensibility" if
2097     offsets passed as NULL with zero offset count.
2099     2. The config.guess and config.sub files had not been updated when I moved to
2100     the latest autoconf.
2103 nigel 53 Version 3.5 15-Aug-01
2104     ---------------------
2105 nigel 5
2106 nigel 53 1. Added some missing #if !defined NOPOSIX conditionals in pcretest.c that
2107     had been forgotten.
2109     2. By using declared but undefined structures, we can avoid using "void"
2110     definitions in pcre.h while keeping the internal definitions of the structures
2111     private.
2113     3. The distribution is now built using autoconf 2.50 and libtool 1.4. From a
2114     user point of view, this means that both static and shared libraries are built
2115     by default, but this can be individually controlled. More of the work of
2116     handling this static/shared cases is now inside libtool instead of PCRE's make
2117     file.
2119     4. The pcretest utility is now installed along with pcregrep because it is
2120     useful for users (to test regexs) and by doing this, it automatically gets
2121     relinked by libtool. The documentation has been turned into a man page, so
2122     there are now .1, .txt, and .html versions in /doc.
2124     5. Upgrades to pcregrep:
2125     (i) Added long-form option names like gnu grep.
2126     (ii) Added --help to list all options with an explanatory phrase.
2127     (iii) Added -r, --recursive to recurse into sub-directories.
2128     (iv) Added -f, --file to read patterns from a file.
2130     6. pcre_exec() was referring to its "code" argument before testing that
2131     argument for NULL (and giving an error if it was NULL).
2133     7. Upgraded Makefile.in to allow for compiling in a different directory from
2134     the source directory.
2136     8. Tiny buglet in pcretest: when pcre_fullinfo() was called to retrieve the
2137     options bits, the pointer it was passed was to an int instead of to an unsigned
2138     long int. This mattered only on 64-bit systems.
2140     9. Fixed typo (3.4/1) in pcre.h again. Sigh. I had changed pcre.h (which is
2141     generated) instead of pcre.in, which it its source. Also made the same change
2142     in several of the .c files.
2144     10. A new release of gcc defines printf() as a macro, which broke pcretest
2145     because it had an ifdef in the middle of a string argument for printf(). Fixed
2146     by using separate calls to printf().
2148     11. Added --enable-newline-is-cr and --enable-newline-is-lf to the configure
2149     script, to force use of CR or LF instead of \n in the source. On non-Unix
2150     systems, the value can be set in config.h.
2152     12. The limit of 200 on non-capturing parentheses is a _nesting_ limit, not an
2153     absolute limit. Changed the text of the error message to make this clear, and
2154     likewise updated the man page.
2156     13. The limit of 99 on the number of capturing subpatterns has been removed.
2157     The new limit is 65535, which I hope will not be a "real" limit.
2160 nigel 51 Version 3.4 22-Aug-00
2161     ---------------------
2163     1. Fixed typo in pcre.h: unsigned const char * changed to const unsigned char *.
2165     2. Diagnose condition (?(0) as an error instead of crashing on matching.
2168 nigel 49 Version 3.3 01-Aug-00
2169     ---------------------
2171     1. If an octal character was given, but the value was greater than \377, it
2172     was not getting masked to the least significant bits, as documented. This could
2173     lead to crashes in some systems.
2175     2. Perl 5.6 (if not earlier versions) accepts classes like [a-\d] and treats
2176     the hyphen as a literal. PCRE used to give an error; it now behaves like Perl.
2178     3. Added the functions pcre_free_substring() and pcre_free_substring_list().
2179     These just pass their arguments on to (pcre_free)(), but they are provided
2180     because some uses of PCRE bind it to non-C systems that can call its functions,
2181     but cannot call free() or pcre_free() directly.
2183     4. Add "make test" as a synonym for "make check". Corrected some comments in
2184     the Makefile.
2186     5. Add $(DESTDIR)/ in front of all the paths in the "install" target in the
2187     Makefile.
2189     6. Changed the name of pgrep to pcregrep, because Solaris has introduced a
2190     command called pgrep for grepping around the active processes.
2192     7. Added the beginnings of support for UTF-8 character strings.
2194     8. Arranged for the Makefile to pass over the settings of CC, CFLAGS, and
2195     RANLIB to ./ltconfig so that they are used by libtool. I think these are all
2196     the relevant ones. (AR is not passed because ./ltconfig does its own figuring
2197     out for the ar command.)
2200 nigel 47 Version 3.2 12-May-00
2201     ---------------------
2203     This is purely a bug fixing release.
2205     1. If the pattern /((Z)+|A)*/ was matched agained ZABCDEFG it matched Z instead
2206     of ZA. This was just one example of several cases that could provoke this bug,
2207     which was introduced by change 9 of version 2.00. The code for breaking
2208     infinite loops after an iteration that matches an empty string was't working
2209     correctly.
2211     2. The pcretest program was not imitating Perl correctly for the pattern /a*/g
2212     when matched against abbab (for example). After matching an empty string, it
2213     wasn't forcing anchoring when setting PCRE_NOTEMPTY for the next attempt; this
2214     caused it to match further down the string than it should.
2216     3. The code contained an inclusion of sys/types.h. It isn't clear why this
2217     was there because it doesn't seem to be needed, and it causes trouble on some
2218     systems, as it is not a Standard C header. It has been removed.
2220     4. Made 4 silly changes to the source to avoid stupid compiler warnings that
2221     were reported on the Macintosh. The changes were from
2223     while ((c = *(++ptr)) != 0 && c != '\n');
2224     to
2225     while ((c = *(++ptr)) != 0 && c != '\n') ;
2227     Totally extraordinary, but if that's what it takes...
2229     5. PCRE is being used in one environment where neither memmove() nor bcopy() is
2230     available. Added HAVE_BCOPY and an autoconf test for it; if neither
2231     HAVE_MEMMOVE nor HAVE_BCOPY is set, use a built-in emulation function which
2232     assumes the way PCRE uses memmove() (always moving upwards).
2234     6. PCRE is being used in one environment where strchr() is not available. There
2235     was only one use in pcre.c, and writing it out to avoid strchr() probably gives
2236     faster code anyway.
2239 nigel 45 Version 3.1 09-Feb-00
2240     ---------------------
2242     The only change in this release is the fixing of some bugs in Makefile.in for
2243     the "install" target:
2245     (1) It was failing to install pcreposix.h.
2247     (2) It was overwriting the pcre.3 man page with the pcreposix.3 man page.
2250 nigel 43 Version 3.0 01-Feb-00
2251     ---------------------
2252 nigel 41
2253     1. Add support for the /+ modifier to perltest (to output $` like it does in
2254     pcretest).
2256     2. Add support for the /g modifier to perltest.
2258     3. Fix pcretest so that it behaves even more like Perl for /g when the pattern
2259     matches null strings.
2261     4. Fix perltest so that it doesn't do unwanted things when fed an empty
2262     pattern. Perl treats empty patterns specially - it reuses the most recent
2263     pattern, which is not what we want. Replace // by /(?#)/ in order to avoid this
2264     effect.
2266     5. The POSIX interface was broken in that it was just handing over the POSIX
2267     captured string vector to pcre_exec(), but (since release 2.00) PCRE has
2268     required a bigger vector, with some working space on the end. This means that
2269     the POSIX wrapper now has to get and free some memory, and copy the results.
2271 nigel 43 6. Added some simple autoconf support, placing the test data and the
2272     documentation in separate directories, re-organizing some of the
2273     information files, and making it build pcre-config (a GNU standard). Also added
2274     libtool support for building PCRE as a shared library, which is now the
2275     default.
2276 nigel 41
2277 nigel 43 7. Got rid of the leading zero in the definition of PCRE_MINOR because 08 and
2278     09 are not valid octal constants. Single digits will be used for minor values
2279     less than 10.
2281     8. Defined REG_EXTENDED and REG_NOSUB as zero in the POSIX header, so that
2282     existing programs that set these in the POSIX interface can use PCRE without
2283     modification.
2285     9. Added a new function, pcre_fullinfo() with an extensible interface. It can
2286     return all that pcre_info() returns, plus additional data. The pcre_info()
2287     function is retained for compatibility, but is considered to be obsolete.
2289     10. Added experimental recursion feature (?R) to handle one common case that
2290     Perl 5.6 will be able to do with (?p{...}).
2292     11. Added support for POSIX character classes like [:alpha:], which Perl is
2293     adopting.
2296 nigel 39 Version 2.08 31-Aug-99
2297     ----------------------
2299     1. When startoffset was not zero and the pattern began with ".*", PCRE was not
2300     trying to match at the startoffset position, but instead was moving forward to
2301     the next newline as if a previous match had failed.
2303     2. pcretest was not making use of PCRE_NOTEMPTY when repeating for /g and /G,
2304     and could get into a loop if a null string was matched other than at the start
2305     of the subject.
2307     3. Added definitions of PCRE_MAJOR and PCRE_MINOR to pcre.h so the version can
2308     be distinguished at compile time, and for completeness also added PCRE_DATE.
2310     5. Added Paul Sokolovsky's minor changes to make it easy to compile a Win32 DLL
2311     in GnuWin32 environments.
2314 nigel 37 Version 2.07 29-Jul-99
2315     ----------------------
2317     1. The documentation is now supplied in plain text form and HTML as well as in
2318     the form of man page sources.
2320     2. C++ compilers don't like assigning (void *) values to other pointer types.
2321     In particular this affects malloc(). Although there is no problem in Standard
2322     C, I've put in casts to keep C++ compilers happy.
2324     3. Typo on pcretest.c; a cast of (unsigned char *) in the POSIX regexec() call
2325     should be (const char *).
2327     4. If NOPOSIX is defined, pcretest.c compiles without POSIX support. This may
2328     be useful for non-Unix systems who don't want to bother with the POSIX stuff.
2329     However, I haven't made this a standard facility. The documentation doesn't
2330     mention it, and the Makefile doesn't support it.
2332     5. The Makefile now contains an "install" target, with editable destinations at
2333     the top of the file. The pcretest program is not installed.
2335     6. pgrep -V now gives the PCRE version number and date.
2337     7. Fixed bug: a zero repetition after a literal string (e.g. /abcde{0}/) was
2338     causing the entire string to be ignored, instead of just the last character.
2340     8. If a pattern like /"([^\\"]+|\\.)*"/ is applied in the normal way to a
2341     non-matching string, it can take a very, very long time, even for strings of
2342     quite modest length, because of the nested recursion. PCRE now does better in
2343     some of these cases. It does this by remembering the last required literal
2344     character in the pattern, and pre-searching the subject to ensure it is present
2345     before running the real match. In other words, it applies a heuristic to detect
2346     some types of certain failure quickly, and in the above example, if presented
2347     with a string that has no trailing " it gives "no match" very quickly.
2349     9. A new runtime option PCRE_NOTEMPTY causes null string matches to be ignored;
2350     other alternatives are tried instead.
2353 nigel 35 Version 2.06 09-Jun-99
2354     ----------------------
2356     1. Change pcretest's output for amount of store used to show just the code
2357     space, because the remainder (the data block) varies in size between 32-bit and
2358     64-bit systems.
2360     2. Added an extra argument to pcre_exec() to supply an offset in the subject to
2361     start matching at. This allows lookbehinds to work when searching for multiple
2362     occurrences in a string.
2364     3. Added additional options to pcretest for testing multiple occurrences:
2366     /+ outputs the rest of the string that follows a match
2367     /g loops for multiple occurrences, using the new startoffset argument
2368     /G loops for multiple occurrences by passing an incremented pointer
2370     4. PCRE wasn't doing the "first character" optimization for patterns starting
2371     with \b or \B, though it was doing it for other lookbehind assertions. That is,
2372     it wasn't noticing that a match for a pattern such as /\bxyz/ has to start with
2373     the letter 'x'. On long subject strings, this gives a significant speed-up.
2376 nigel 33 Version 2.05 21-Apr-99
2377     ----------------------
2379     1. Changed the type of magic_number from int to long int so that it works
2380     properly on 16-bit systems.
2382     2. Fixed a bug which caused patterns starting with .* not to work correctly
2383     when the subject string contained newline characters. PCRE was assuming
2384     anchoring for such patterns in all cases, which is not correct because .* will
2385     not pass a newline unless PCRE_DOTALL is set. It now assumes anchoring only if
2386     DOTALL is set at top level; otherwise it knows that patterns starting with .*
2387     must be retried after every newline in the subject.
2390 nigel 31 Version 2.04 18-Feb-99
2391     ----------------------
2393     1. For parenthesized subpatterns with repeats whose minimum was zero, the
2394     computation of the store needed to hold the pattern was incorrect (too large).
2395     If such patterns were nested a few deep, this could multiply and become a real
2396     problem.
2398     2. Added /M option to pcretest to show the memory requirement of a specific
2399     pattern. Made -m a synonym of -s (which does this globally) for compatibility.
2401     3. Subpatterns of the form (regex){n,m} (i.e. limited maximum) were being
2402     compiled in such a way that the backtracking after subsequent failure was
2403     pessimal. Something like (a){0,3} was compiled as (a)?(a)?(a)? instead of
2404     ((a)((a)(a)?)?)? with disastrous performance if the maximum was of any size.
2407 nigel 29 Version 2.03 02-Feb-99
2408     ----------------------
2410     1. Fixed typo and small mistake in man page.
2412 nigel 31 2. Added 4th condition (GPL supersedes if conflict) and created separate
2413     LICENCE file containing the conditions.
2414 nigel 29
2415     3. Updated pcretest so that patterns such as /abc\/def/ work like they do in
2416     Perl, that is the internal \ allows the delimiter to be included in the
2417     pattern. Locked out the use of \ as a delimiter. If \ immediately follows
2418     the final delimiter, add \ to the end of the pattern (to test the error).
2420     4. Added the convenience functions for extracting substrings after a successful
2421     match. Updated pcretest to make it able to test these functions.
2424 nigel 27 Version 2.02 14-Jan-99
2425     ----------------------
2427     1. Initialized the working variables associated with each extraction so that
2428     their saving and restoring doesn't refer to uninitialized store.
2430     2. Put dummy code into study.c in order to trick the optimizer of the IBM C
2431     compiler for OS/2 into generating correct code. Apparently IBM isn't going to
2432     fix the problem.
2434     3. Pcretest: the timing code wasn't using LOOPREPEAT for timing execution
2435     calls, and wasn't printing the correct value for compiling calls. Increased the
2436     default value of LOOPREPEAT, and the number of significant figures in the
2437     times.
2439     4. Changed "/bin/rm" in the Makefile to "-rm" so it works on Windows NT.
2441     5. Renamed "deftables" as "dftables" to get it down to 8 characters, to avoid
2442     a building problem on Windows NT with a FAT file system.
2445 nigel 25 Version 2.01 21-Oct-98
2446     ----------------------
2448     1. Changed the API for pcre_compile() to allow for the provision of a pointer
2449     to character tables built by pcre_maketables() in the current locale. If NULL
2450     is passed, the default tables are used.
2453 nigel 23 Version 2.00 24-Sep-98
2454 nigel 21 ----------------------
2456 nigel 23 1. Since the (>?) facility is in Perl 5.005, don't require PCRE_EXTRA to enable
2457     it any more.
2459     2. Allow quantification of (?>) groups, and make it work correctly.
2461     3. The first character computation wasn't working for (?>) groups.
2463     4. Correct the implementation of \Z (it is permitted to match on the \n at the
2464     end of the subject) and add 5.005's \z, which really does match only at the
2465     very end of the subject.
2467     5. Remove the \X "cut" facility; Perl doesn't have it, and (?> is neater.
2469     6. Remove the ability to specify CASELESS, MULTILINE, DOTALL, and
2470     DOLLAR_END_ONLY at runtime, to make it possible to implement the Perl 5.005
2471     localized options. All options to pcre_study() were also removed.
2473     7. Add other new features from 5.005:
2475     $(?<= positive lookbehind
2476     $(?<! negative lookbehind
2477     (?imsx-imsx) added the unsetting capability
2478     such a setting is global if at outer level; local otherwise
2479     (?imsx-imsx:) non-capturing groups with option setting
2480     (?(cond)re|re) conditional pattern matching
2482     A backreference to itself in a repeated group matches the previous
2483     captured string.
2485     8. General tidying up of studying (both automatic and via "study")
2486     consequential on the addition of new assertions.
2488     9. As in 5.005, unlimited repeated groups that could match an empty substring
2489     are no longer faulted at compile time. Instead, the loop is forcibly broken at
2490     runtime if any iteration does actually match an empty substring.
2492     10. Include the RunTest script in the distribution.
2494     11. Added tests from the Perl 5.005_02 distribution. This showed up a few
2495     discrepancies, some of which were old and were also with respect to 5.004. They
2496     have now been fixed.
2499     Version 1.09 28-Apr-98
2500     ----------------------
2502 nigel 21 1. A negated single character class followed by a quantifier with a minimum
2503     value of one (e.g. [^x]{1,6} ) was not compiled correctly. This could lead to
2504     program crashes, or just wrong answers. This did not apply to negated classes
2505     containing more than one character, or to minima other than one.
2508 nigel 19 Version 1.08 27-Mar-98
2509     ----------------------
2511     1. Add PCRE_UNGREEDY to invert the greediness of quantifiers.
2513     2. Add (?U) and (?X) to set PCRE_UNGREEDY and PCRE_EXTRA respectively. The
2514     latter must appear before anything that relies on it in the pattern.
2517 nigel 17 Version 1.07 16-Feb-98
2518     ----------------------
2520     1. A pattern such as /((a)*)*/ was not being diagnosed as in error (unlimited
2521     repeat of a potentially empty string).
2524 nigel 15 Version 1.06 23-Jan-98
2525     ----------------------
2527     1. Added Markus Oberhumer's little patches for C++.
2529     2. Literal strings longer than 255 characters were broken.
2532 nigel 13 Version 1.05 23-Dec-97
2533     ----------------------
2535     1. Negated character classes containing more than one character were failing if
2536     PCRE_CASELESS was set at run time.
2539 nigel 11 Version 1.04 19-Dec-97
2540     ----------------------
2542     1. Corrected the man page, where some "const" qualifiers had been omitted.
2544     2. Made debugging output print "{0,xxx}" instead of just "{,xxx}" to agree with
2545     input syntax.
2547     3. Fixed memory leak which occurred when a regex with back references was
2548     matched with an offsets vector that wasn't big enough. The temporary memory
2549     that is used in this case wasn't being freed if the match failed.
2551     4. Tidied pcretest to ensure it frees memory that it gets.
2553     5. Temporary memory was being obtained in the case where the passed offsets
2554     vector was exactly big enough.
2556     6. Corrected definition of offsetof() from change 5 below.
2558     7. I had screwed up change 6 below and broken the rules for the use of
2559     setjmp(). Now fixed.
2562 nigel 9 Version 1.03 18-Dec-97
2563     ----------------------
2565     1. A erroneous regex with a missing opening parenthesis was correctly
2566     diagnosed, but PCRE attempted to access brastack[-1], which could cause crashes
2567     on some systems.
2569     2. Replaced offsetof(real_pcre, code) by offsetof(real_pcre, code[0]) because
2570     it was reported that one broken compiler failed on the former because "code" is
2571     also an independent variable.
2573     3. The erroneous regex a[]b caused an array overrun reference.
2575     4. A regex ending with a one-character negative class (e.g. /[^k]$/) did not
2576     fail on data ending with that character. (It was going on too far, and checking
2577     the next character, typically a binary zero.) This was specific to the
2578     optimized code for single-character negative classes.
2580     5. Added a contributed patch from the TIN world which does the following:
2582     + Add an undef for memmove, in case the the system defines a macro for it.
2584     + Add a definition of offsetof(), in case there isn't one. (I don't know
2585     the reason behind this - offsetof() is part of the ANSI standard - but
2586     it does no harm).
2588     + Reduce the ifdef's in pcre.c using macro DPRINTF, thereby eliminating
2589     most of the places where whitespace preceded '#'. I have given up and
2590     allowed the remaining 2 cases to be at the margin.
2592     + Rename some variables in pcre to eliminate shadowing. This seems very
2593     pedantic, but does no harm, of course.
2595     6. Moved the call to setjmp() into its own function, to get rid of warnings
2596     from gcc -Wall, and avoided calling it at all unless PCRE_EXTRA is used.
2598     7. Constructs such as \d{8,} were compiling into the equivalent of
2599 nigel 11 \d{8}\d{0,65527} instead of \d{8}\d* which didn't make much difference to the
2600 nigel 9 outcome, but in this particular case used more store than had been allocated,
2601     which caused the bug to be discovered because it threw up an internal error.
2603     8. The debugging code in both pcre and pcretest for outputting the compiled
2604     form of a regex was going wrong in the case of back references followed by
2605     curly-bracketed repeats.
2608 nigel 7 Version 1.02 12-Dec-97
2609     ----------------------
2611     1. Typos in pcre.3 and comments in the source fixed.
2613     2. Applied a contributed patch to get rid of places where it used to remove
2614     'const' from variables, and fixed some signed/unsigned and uninitialized
2615     variable warnings.
2617     3. Added the "runtest" target to Makefile.
2619     4. Set default compiler flag to -O2 rather than just -O.
2622 nigel 5 Version 1.01 19-Nov-97
2623     ----------------------
2625     1. PCRE was failing to diagnose unlimited repeat of empty string for patterns
2626     like /([ab]*)*/, that is, for classes with more than one character in them.
2628     2. Likewise, it wasn't diagnosing patterns with "once-only" subpatterns, such
2629     as /((?>a*))*/ (a PCRE_EXTRA facility).
2632     Version 1.00 18-Nov-97
2633     ----------------------
2635     1. Added compile-time macros to support systems such as SunOS4 which don't have
2636     memmove() or strerror() but have other things that can be used instead.
2638     2. Arranged that "make clean" removes the executables.
2641 nigel 3 Version 0.99 27-Oct-97
2642     ----------------------
2644     1. Fixed bug in code for optimizing classes with only one character. It was
2645     initializing a 32-byte map regardless, which could cause it to run off the end
2646     of the memory it had got.
2648     2. Added, conditional on PCRE_EXTRA, the proposed (?>REGEX) construction.
2651     Version 0.98 22-Oct-97
2652     ----------------------
2654     1. Fixed bug in code for handling temporary memory usage when there are more
2655     back references than supplied space in the ovector. This could cause segfaults.
2658     Version 0.97 21-Oct-97
2659     ----------------------
2661     1. Added the \X "cut" facility, conditional on PCRE_EXTRA.
2663     2. Optimized negated single characters not to use a bit map.
2665     3. Brought error texts together as macro definitions; clarified some of them;
2666     fixed one that was wrong - it said "range out of order" when it meant "invalid
2667     escape sequence".
2669     4. Changed some char * arguments to const char *.
2671     5. Added PCRE_NOTBOL and PCRE_NOTEOL (from POSIX).
2673     6. Added the POSIX-style API wrapper in pcreposix.a and testing facilities in
2674     pcretest.
2677     Version 0.96 16-Oct-97
2678     ----------------------
2680     1. Added a simple "pgrep" utility to the distribution.
2682     2. Fixed an incompatibility with Perl: "{" is now treated as a normal character
2683     unless it appears in one of the precise forms "{ddd}", "{ddd,}", or "{ddd,ddd}"
2684     where "ddd" means "one or more decimal digits".
2686     3. Fixed serious bug. If a pattern had a back reference, but the call to
2687     pcre_exec() didn't supply a large enough ovector to record the related
2688     identifying subpattern, the match always failed. PCRE now remembers the number
2689     of the largest back reference, and gets some temporary memory in which to save
2690     the offsets during matching if necessary, in order to ensure that
2691     backreferences always work.
2693     4. Increased the compatibility with Perl in a number of ways:
2695     (a) . no longer matches \n by default; an option PCRE_DOTALL is provided
2696     to request this handling. The option can be set at compile or exec time.
2698     (b) $ matches before a terminating newline by default; an option
2699     PCRE_DOLLAR_ENDONLY is provided to override this (but not in multiline
2700     mode). The option can be set at compile or exec time.
2702     (c) The handling of \ followed by a digit other than 0 is now supposed to be
2703     the same as Perl's. If the decimal number it represents is less than 10
2704     or there aren't that many previous left capturing parentheses, an octal
2705     escape is read. Inside a character class, it's always an octal escape,
2706     even if it is a single digit.
2708     (d) An escaped but undefined alphabetic character is taken as a literal,
2709     unless PCRE_EXTRA is set. Currently this just reserves the remaining
2710     escapes.
2712     (e) {0} is now permitted. (The previous item is removed from the compiled
2713     pattern).
2715     5. Changed all the names of code files so that the basic parts are no longer
2716     than 10 characters, and abolished the teeny "globals.c" file.
2718     6. Changed the handling of character classes; they are now done with a 32-byte
2719     bit map always.
2721     7. Added the -d and /D options to pcretest to make it possible to look at the
2722     internals of compilation without having to recompile pcre.
2725     Version 0.95 23-Sep-97
2726     ----------------------
2728     1. Fixed bug in pre-pass concerning escaped "normal" characters such as \x5c or
2729     \x20 at the start of a run of normal characters. These were being treated as
2730     real characters, instead of the source characters being re-checked.
2733     Version 0.94 18-Sep-97
2734     ----------------------
2736     1. The functions are now thread-safe, with the caveat that the global variables
2737     containing pointers to malloc() and free() or alternative functions are the
2738     same for all threads.
2740     2. Get pcre_study() to generate a bitmap of initial characters for non-
2741     anchored patterns when this is possible, and use it if passed to pcre_exec().
2744     Version 0.93 15-Sep-97
2745     ----------------------
2747     1. /(b)|(:+)/ was computing an incorrect first character.
2749     2. Add pcre_study() to the API and the passing of pcre_extra to pcre_exec(),
2750     but not actually doing anything yet.
2752     3. Treat "-" characters in classes that cannot be part of ranges as literals,
2753     as Perl does (e.g. [-az] or [az-]).
2755     4. Set the anchored flag if a branch starts with .* or .*? because that tests
2756     all possible positions.
2758     5. Split up into different modules to avoid including unneeded functions in a
2759     compiled binary. However, compile and exec are still in one module. The "study"
2760     function is split off.
2762     6. The character tables are now in a separate module whose source is generated
2763     by an auxiliary program - but can then be edited by hand if required. There are
2764     now no calls to isalnum(), isspace(), isdigit(), isxdigit(), tolower() or
2765     toupper() in the code.
2767     7. Turn the malloc/free funtions variables into pcre_malloc and pcre_free and
2768     make them global. Abolish the function for setting them, as the caller can now
2769     set them directly.
2772     Version 0.92 11-Sep-97
2773     ----------------------
2775     1. A repeat with a fixed maximum and a minimum of 1 for an ordinary character
2776     (e.g. /a{1,3}/) was broken (I mis-optimized it).
2778     2. Caseless matching was not working in character classes if the characters in
2779     the pattern were in upper case.
2781     3. Make ranges like [W-c] work in the same way as Perl for caseless matching.
2783     4. Make PCRE_ANCHORED public and accept as a compile option.
2785     5. Add an options word to pcre_exec() and accept PCRE_ANCHORED and
2786     PCRE_CASELESS at run time. Add escapes \A and \I to pcretest to cause it to
2787     pass them.
2789     6. Give an error if bad option bits passed at compile or run time.
2791     7. Add PCRE_MULTILINE at compile and exec time, and (?m) as well. Add \M to
2792     pcretest to cause it to pass that flag.
2794     8. Add pcre_info(), to get the number of identifying subpatterns, the stored
2795     options, and the first character, if set.
2797     9. Recognize C+ or C{n,m} where n >= 1 as providing a fixed starting character.
2800     Version 0.91 10-Sep-97
2801     ----------------------
2803     1. PCRE was failing to diagnose unlimited repeats of subpatterns that could
2804     match the empty string as in /(a*)*/. It was looping and ultimately crashing.
2806     2. PCRE was looping on encountering an indefinitely repeated back reference to
2807     a subpattern that had matched an empty string, e.g. /(a|)\1*/. It now does what
2808     Perl does - treats the match as successful.
2810     ****


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