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Revision 100 - (hide annotations) (download)
Tue Mar 6 14:53:10 2007 UTC (8 years, 1 month ago) by ph10
File size: 120448 byte(s)
Updated comments in configure.ac that end up in config.h.in, and arrange for 
config.h to be distributed (compare pcre.h).

1 nigel 3 ChangeLog for PCRE
2     ------------------
4 ph10 98 Version 7.1 05-Mar-07
5     ---------------------
7     1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
8 ph10 99 that is more "standard", making use of automake and other autotools. There
9     is some re-arrangement of the files and adjustment of comments consequent
10     on this.
12 ph10 100 2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
13     for recursive directory scanning broke on some systems because the files
14     are not scanned in any specific order and on different systems the order
15     was different. A call to "sort" has been inserted into RunGrepTest for the
16     approprate test as a short-term fix. In the longer term there may be an
17     alternative.
19     3. I had an email from Eric Raymond about problems translating some of PCRE's
20 ph10 99 man pages to HTML (despite the fact that I distribute HTML pages, some
21     people do their own conversions for various reasons). The problems
22     concerned the use of low-level troff macros .br and .in. I have therefore
23     removed all such uses from the man pages (some were redundant, some could
24     be replaced by .nf/.fi pairs). The maintain/132html script that I use to
25     generate HTML has been updated to handle .nf/.fi and to complain if it
26     encounters .br or .in.
28 ph10 100 4. Updated comments in configure.ac that get placed in config.h.in and also
29     arranged for config.h to be included in the distribution, for the benefit
30     of those who have to compile without Autotools (compare pcre.h).
32 ph10 98
33 nigel 93 Version 7.0 19-Dec-06
34     ---------------------
36     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
37     moving to gcc 4.1.1.
39     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
40     sys/time.h, which is documented as needed for this function. It doesn't
41     seem to matter on Linux, but it showed up on some releases of OS X.
43     3. It seems that there are systems where bytes whose values are greater than
44     127 match isprint() in the "C" locale. The "C" locale should be the
45     default when a C program starts up. In most systems, only ASCII printing
46     characters match isprint(). This difference caused the output from pcretest
47     to vary, making some of the tests fail. I have changed pcretest so that:
49     (a) When it is outputting text in the compiled version of a pattern, bytes
50     other than 32-126 are always shown as hex escapes.
52     (b) When it is outputting text that is a matched part of a subject string,
53     it does the same, unless a different locale has been set for the match
54     (using the /L modifier). In this case, it uses isprint() to decide.
56     4. Fixed a major bug that caused incorrect computation of the amount of memory
57     required for a compiled pattern when options that changed within the
58     pattern affected the logic of the preliminary scan that determines the
59     length. The relevant options are -x, and -i in UTF-8 mode. The result was
60     that the computed length was too small. The symptoms of this bug were
61     either the PCRE error "internal error: code overflow" from pcre_compile(),
62     or a glibc crash with a message such as "pcretest: free(): invalid next
63     size (fast)". Examples of patterns that provoked this bug (shown in
64     pcretest format) are:
66     /(?-x: )/x
67     /(?x)(?-x: \s*#\s*)/
68     /((?i)[\x{c0}])/8
69     /(?i:[\x{c0}])/8
71     HOWEVER: Change 17 below makes this fix obsolete as the memory computation
72     is now done differently.
74     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
75     wrapper classes; (b) implement a new function in the C++ scanner that is
76     more efficient than the old way of doing things because it avoids levels of
77     recursion in the regex matching; (c) add a paragraph to the documentation
78     for the FullMatch() function.
80     6. The escape sequence \n was being treated as whatever was defined as
81     "newline". Not only was this contrary to the documentation, which states
82     that \n is character 10 (hex 0A), but it also went horribly wrong when
83     "newline" was defined as CRLF. This has been fixed.
85     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
86     was being set to -1 for the "end of line" case (supposedly a value that no
87     character can have). Though this value is never used (the check for end of
88     line is "zero bytes in current character"), it caused compiler complaints.
89     I've changed it to 0xffffffff.
91     8. In pcre_version.c, the version string was being built by a sequence of
92     C macros that, in the event of PCRE_PRERELEASE being defined as an empty
93     string (as it is for production releases) called a macro with an empty
94     argument. The C standard says the result of this is undefined. The gcc
95     compiler treats it as an empty string (which was what was wanted) but it is
96     reported that Visual C gives an error. The source has been hacked around to
97     avoid this problem.
99     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
100     builds of pcretest, and changed the call to _setmode() to use _O_BINARY
101     instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
102     of them did).
104     10. Originally, pcretest opened its input and output without "b"; then I was
105     told that "b" was needed in some environments, so it was added for release
106     5.0 to both the input and output. (It makes no difference on Unix-like
107     systems.) Later I was told that it is wrong for the input on Windows. I've
108     now abstracted the modes into two macros, to make it easier to fiddle with
109     them, and removed "b" from the input mode under Windows.
111     11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
113     12. Added -help and --help to pcretest as an official way of being reminded
114     of the options.
116     13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
117     and pcrecpp.cc because they annoy compilers at high warning levels.
119     14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
121     15. Fixed an occurrence of == in configure.ac that should have been = (shell
122     scripts are not C programs :-) and which was not noticed because it works
123     on Linux.
125     16. pcretest is supposed to handle any length of pattern and data line (as one
126     line or as a continued sequence of lines) by extending its input buffer if
127     necessary. This feature was broken for very long pattern lines, leading to
128     a string of junk being passed to pcre_compile() if the pattern was longer
129     than about 50K.
131     17. I have done a major re-factoring of the way pcre_compile() computes the
132     amount of memory needed for a compiled pattern. Previously, there was code
133     that made a preliminary scan of the pattern in order to do this. That was
134     OK when PCRE was new, but as the facilities have expanded, it has become
135     harder and harder to keep it in step with the real compile phase, and there
136     have been a number of bugs (see for example, 4 above). I have now found a
137     cunning way of running the real compile function in a "fake" mode that
138     enables it to compute how much memory it would need, while actually only
139     ever using a few hundred bytes of working memory and without too many
140     tests of the mode. This should make future maintenance and development
141     easier. A side effect of this work is that the limit of 200 on the nesting
142     depth of parentheses has been removed (though this was never a serious
143     limitation, I suspect). However, there is a downside: pcre_compile() now
144     runs more slowly than before (30% or more, depending on the pattern). I
145     hope this isn't a big issue. There is no effect on runtime performance.
147     18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
148     newline (only possible for the last line of a file) and it was a
149     pattern that set a locale (followed by /Lsomething), pcretest crashed.
151     19. Added additional timing features to pcretest. (1) The -tm option now times
152     matching only, not compiling. (2) Both -t and -tm can be followed, as a
153     separate command line item, by a number that specifies the number of
154     repeats to use when timing. The default is 50000; this gives better
155     precision, but takes uncomfortably long for very large patterns.
157     20. Extended pcre_study() to be more clever in cases where a branch of a
158     subpattern has no definite first character. For example, (a*|b*)[cd] would
159     previously give no result from pcre_study(). Now it recognizes that the
160     first character must be a, b, c, or d.
162     21. There was an incorrect error "recursive call could loop indefinitely" if
163     a subpattern (or the entire pattern) that was being tested for matching an
164     empty string contained only one non-empty item after a nested subpattern.
165     For example, the pattern (?>\x{100}*)\d(?R) provoked this error
166     incorrectly, because the \d was being skipped in the check.
168     22. The pcretest program now has a new pattern option /B and a command line
169     option -b, which is equivalent to adding /B to every pattern. This causes
170     it to show the compiled bytecode, without the additional information that
171     -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
172     is the same as /B/I).
174     23. A new optimization is now able automatically to treat some sequences such
175     as a*b as a*+b. More specifically, if something simple (such as a character
176     or a simple class like \d) has an unlimited quantifier, and is followed by
177     something that cannot possibly match the quantified thing, the quantifier
178     is automatically "possessified".
180     24. A recursive reference to a subpattern whose number was greater than 39
181     went wrong under certain circumstances in UTF-8 mode. This bug could also
182     have affected the operation of pcre_study().
184     25. Realized that a little bit of performance could be had by replacing
185     (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
187     26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
189     27. Possessive quantifiers such as a++ were previously implemented by turning
190     them into atomic groups such as ($>a+). Now they have their own opcodes,
191     which improves performance. This includes the automatically created ones
192     from 23 above.
194     28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
195     lookahead was broken if it was not anchored. PCRE was mistakenly expecting
196     the first matched character to be a colon. This applied both to named and
197     numbered groups.
199     29. The ucpinternal.h header file was missing its idempotency #ifdef.
201     30. I was sent a "project" file called libpcre.a.dev which I understand makes
202     building PCRE on Windows easier, so I have included it in the distribution.
204     31. There is now a check in pcretest against a ridiculously large number being
205     returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
206     loop, the loop is abandoned.
208     32. Forward references to subpatterns in conditions such as (?(2)...) where
209     subpattern 2 is defined later cause pcre_compile() to search forwards in
210     the pattern for the relevant set of parentheses. This search went wrong
211     when there were unescaped parentheses in a character class, parentheses
212     escaped with \Q...\E, or parentheses in a #-comment in /x mode.
214     33. "Subroutine" calls and backreferences were previously restricted to
215     referencing subpatterns earlier in the regex. This restriction has now
216     been removed.
218     34. Added a number of extra features that are going to be in Perl 5.10. On the
219     whole, these are just syntactic alternatives for features that PCRE had
220     previously implemented using the Python syntax or my own invention. The
221     other formats are all retained for compatibility.
223     (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
224     as (?P<name>...). The new forms, as well as being in Perl 5.10, are
225     also .NET compatible.
227     (b) A recursion or subroutine call to a named group can now be defined as
228     (?&name) as well as (?P>name).
230     (c) A backreference to a named group can now be defined as \k<name> or
231     \k'name' as well as (?P=name). The new forms, as well as being in Perl
232     5.10, are also .NET compatible.
234     (d) A conditional reference to a named group can now use the syntax
235     (?(<name>) or (?('name') as well as (?(name).
237     (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
238     groups (named and numbered) that are never evaluated inline, but can be
239     called as "subroutines" from elsewhere. In effect, the DEFINE condition
240     is always false. There may be only one alternative in such a group.
242     (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
243     as the simple (?(R). The condition is true only if the most recent
244     recursion is that of the given number or name. It does not search out
245     through the entire recursion stack.
247     (g) The escape \gN or \g{N} has been added, where N is a positive or
248     negative number, specifying an absolute or relative reference.
250     35. Tidied to get rid of some further signed/unsigned compiler warnings and
251     some "unreachable code" warnings.
253     36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
254     things, this adds five new scripts.
256     37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
257     There were also incompatibilities regarding the handling of \Q..\E inside
258     character classes, for example with patterns like [\Qa\E-\Qz\E] where the
259     hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
261     38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
262     matches an empty string, and forcibly breaks the loop. There were bugs in
263     this code in non-simple cases. For a pattern such as ^(a()*)* matched
264     against aaaa the result was just "a" rather than "aaaa", for example. Two
265     separate and independent bugs (that affected different cases) have been
266     fixed.
268     39. Refactored the code to abolish the use of different opcodes for small
269     capturing bracket numbers. This is a tidy that I avoided doing when I
270     removed the limit on the number of capturing brackets for 3.5 back in 2001.
271     The new approach is not only tidier, it makes it possible to reduce the
272     memory needed to fix the previous bug (38).
274     40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
275     sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
276     processing dot, circumflex, or dollar metacharacters, or #-comments in /x
277     mode.
279     41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
280     report.
282     42. Applied patch, originally from Ari Pollak, modified by Google, to allow
283     copy construction and assignment in the C++ wrapper.
285     43. Updated pcregrep to support "--newline=any". In the process, I fixed a
286     couple of bugs that could have given wrong results in the "--newline=crlf"
287     case.
289     44. Added a number of casts and did some reorganization of signed/unsigned int
290     variables following suggestions from Dair Grant. Also renamed the variable
291     "this" as "item" because it is a C++ keyword.
293     45. Arranged for dftables to add
295     #include "pcre_internal.h"
297     to pcre_chartables.c because without it, gcc 4.x may remove the array
298     definition from the final binary if PCRE is built into a static library and
299     dead code stripping is activated.
301     46. For an unanchored pattern, if a match attempt fails at the start of a
302     newline sequence, and the newline setting is CRLF or ANY, and the next two
303     characters are CRLF, advance by two characters instead of one.
306 nigel 91 Version 6.7 04-Jul-06
307     ---------------------
309     1. In order to handle tests when input lines are enormously long, pcretest has
310     been re-factored so that it automatically extends its buffers when
311     necessary. The code is crude, but this _is_ just a test program. The
312     default size has been increased from 32K to 50K.
314     2. The code in pcre_study() was using the value of the re argument before
315     testing it for NULL. (Of course, in any sensible call of the function, it
316     won't be NULL.)
318     3. The memmove() emulation function in pcre_internal.h, which is used on
319     systems that lack both memmove() and bcopy() - that is, hardly ever -
320     was missing a "static" storage class specifier.
322     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
323     containing an extended class (one that cannot be represented by a bitmap
324     because it contains high-valued characters or Unicode property items, e.g.
325     [\pZ]). Almost always one would set UTF-8 mode when processing such a
326     pattern, but PCRE should not loop if you do not (it no longer does).
327     [Detail: two cases were found: (a) a repeated subpattern containing an
328     extended class; (b) a recursive reference to a subpattern that followed a
329     previous extended class. It wasn't skipping over the extended class
330     correctly when UTF-8 mode was not set.]
332     5. A negated single-character class was not being recognized as fixed-length
333     in lookbehind assertions such as (?<=[^f]), leading to an incorrect
334     compile error "lookbehind assertion is not fixed length".
336     6. The RunPerlTest auxiliary script was showing an unexpected difference
337     between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
338     write a Perl script that can interpret lines of an input file either as
339     byte characters or as UTF-8, which is what "perltest" was being required to
340     do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
341     can't do is switch easily at run time between having the "use utf8;" pragma
342     or not. In the end, I fudged it by using the RunPerlTest script to insert
343     "use utf8;" explicitly for the UTF-8 tests.
345     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
346     the end of the subject string, contrary to the documentation and to what
347     Perl does. This was true of both matching functions. Now it matches only at
348     the start of the subject and immediately after *internal* newlines.
350     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
351     a pointer to an int instead of a pointer to an unsigned long int. This
352     caused problems on 64-bit systems.
354     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
355     instance of the 'standard' template library not being so standard".
357     10. There was no check on the number of named subpatterns nor the maximum
358     length of a subpattern name. The product of these values is used to compute
359     the size of the memory block for a compiled pattern. By supplying a very
360     long subpattern name and a large number of named subpatterns, the size
361     computation could be caused to overflow. This is now prevented by limiting
362     the length of names to 32 characters, and the number of named subpatterns
363     to 10,000.
365     11. Subpatterns that are repeated with specific counts have to be replicated in
366     the compiled pattern. The size of memory for this was computed from the
367     length of the subpattern and the repeat count. The latter is limited to
368     65535, but there was no limit on the former, meaning that integer overflow
369     could in principle occur. The compiled length of a repeated subpattern is
370     now limited to 30,000 bytes in order to prevent this.
372     12. Added the optional facility to have named substrings with the same name.
374     13. Added the ability to use a named substring as a condition, using the
375     Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
376     are numbers (not recommended). Forward references are permitted.
378     14. Added forward references in named backreferences (if you see what I mean).
380     15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
381     pattern could run off the end of the subject. For example, the pattern
382     "(?s)(.{1,5})"8 did this with the subject "ab".
384     16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
385     PCRE_CASELESS was set when matching characters that were quantified with ?
386     or *.
388     17. A character class other than a single negated character that had a minimum
389     but no maximum quantifier - for example [ab]{6,} - was not handled
390     correctly by pce_dfa_exec(). It would match only one character.
392     18. A valid (though odd) pattern that looked like a POSIX character
393     class but used an invalid character after [ (for example [[,abc,]]) caused
394     pcre_compile() to give the error "Failed: internal error: code overflow" or
395     in some cases to crash with a glibc free() error. This could even happen if
396     the pattern terminated after [[ but there just happened to be a sequence of
397     letters, a binary zero, and a closing ] in the memory that followed.
399     19. Perl's treatment of octal escapes in the range \400 to \777 has changed
400     over the years. Originally (before any Unicode support), just the bottom 8
401     bits were taken. Thus, for example, \500 really meant \100. Nowadays the
402     output from "man perlunicode" includes this:
404     The regular expression compiler produces polymorphic opcodes. That
405     is, the pattern adapts to the data and automatically switches to
406     the Unicode character scheme when presented with Unicode data--or
407     instead uses a traditional byte scheme when presented with byte
408     data.
410     Sadly, a wide octal escape does not cause a switch, and in a string with
411     no other multibyte characters, these octal escapes are treated as before.
412     Thus, in Perl, the pattern /\500/ actually matches \100 but the pattern
413     /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
414     Unicode string.
416     I have not perpetrated such confusion in PCRE. Up till now, it took just
417     the bottom 8 bits, as in old Perl. I have now made octal escapes with
418     values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
419     translate to the appropriate multibyte character.
421     29. Applied some refactoring to reduce the number of warnings from Microsoft
422     and Borland compilers. This has included removing the fudge introduced
423     seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
424     a warning about an unused variable.
426     21. PCRE has not included VT (character 0x0b) in the set of whitespace
427     characters since release 4.0, because Perl (from release 5.004) does not.
428     [Or at least, is documented not to: some releases seem to be in conflict
429     with the documentation.] However, when a pattern was studied with
430     pcre_study() and all its branches started with \s, PCRE still included VT
431     as a possible starting character. Of course, this did no harm; it just
432     caused an unnecessary match attempt.
434     22. Removed a now-redundant internal flag bit that recorded the fact that case
435     dependency changed within the pattern. This was once needed for "required
436     byte" processing, but is no longer used. This recovers a now-scarce options
437     bit. Also moved the least significant internal flag bit to the most-
438     significant bit of the word, which was not previously used (hangover from
439     the days when it was an int rather than a uint) to free up another bit for
440     the future.
442     23. Added support for CRLF line endings as well as CR and LF. As well as the
443     default being selectable at build time, it can now be changed at runtime
444     via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
445     specify that it is scanning data with non-default line endings.
447     24. Changed the definition of CXXLINK to make it agree with the definition of
448     LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
450     25. Applied Ian Taylor's patches to avoid using another stack frame for tail
451     recursions. This makes a big different to stack usage for some patterns.
453     26. If a subpattern containing a named recursion or subroutine reference such
454     as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
455     the space required for the compiled pattern went wrong and gave too small a
456     value. Depending on the environment, this could lead to "Failed: internal
457     error: code overflow at offset 49" or "glibc detected double free or
458     corruption" errors.
460     27. Applied patches from Google (a) to support the new newline modes and (b) to
461     advance over multibyte UTF-8 characters in GlobalReplace.
463     28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
464     difference for some implementation of PCRE in some Windows version.
466     29. Added some extra testing facilities to pcretest:
468     \q<number> in a data line sets the "match limit" value
469     \Q<number> in a data line sets the "match recursion limt" value
470     -S <number> sets the stack size, where <number> is in megabytes
472     The -S option isn't available for Windows.
475 nigel 89 Version 6.6 06-Feb-06
476     ---------------------
478     1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
479     in pcreposix.h. I have copied the definition from pcre.h.
481     2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
482     because pcre.h is no longer a built file.
484     3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
485     not normally included in the compiled code.
488 nigel 87 Version 6.5 01-Feb-06
489     ---------------------
491     1. When using the partial match feature with pcre_dfa_exec(), it was not
492     anchoring the second and subsequent partial matches at the new starting
493     point. This could lead to incorrect results. For example, with the pattern
494     /1234/, partially matching against "123" and then "a4" gave a match.
496     2. Changes to pcregrep:
498     (a) All non-match returns from pcre_exec() were being treated as failures
499     to match the line. Now, unless the error is PCRE_ERROR_NOMATCH, an
500     error message is output. Some extra information is given for the
502     probably the only errors that are likely to be caused by users (by
503     specifying a regex that has nested indefinite repeats, for instance).
504     If there are more than 20 of these errors, pcregrep is abandoned.
506     (b) A binary zero was treated as data while matching, but terminated the
507     output line if it was written out. This has been fixed: binary zeroes
508     are now no different to any other data bytes.
510     (c) Whichever of the LC_ALL or LC_CTYPE environment variables is set is
511     used to set a locale for matching. The --locale=xxxx long option has
512     been added (no short equivalent) to specify a locale explicitly on the
513     pcregrep command, overriding the environment variables.
515     (d) When -B was used with -n, some line numbers in the output were one less
516     than they should have been.
518     (e) Added the -o (--only-matching) option.
520     (f) If -A or -C was used with -c (count only), some lines of context were
521     accidentally printed for the final match.
523     (g) Added the -H (--with-filename) option.
525     (h) The combination of options -rh failed to suppress file names for files
526     that were found from directory arguments.
528     (i) Added the -D (--devices) and -d (--directories) options.
530     (j) Added the -F (--fixed-strings) option.
532     (k) Allow "-" to be used as a file name for -f as well as for a data file.
534     (l) Added the --colo(u)r option.
536     (m) Added Jeffrey Friedl's -S testing option, but within #ifdefs so that it
537     is not present by default.
539     3. A nasty bug was discovered in the handling of recursive patterns, that is,
540     items such as (?R) or (?1), when the recursion could match a number of
541     alternatives. If it matched one of the alternatives, but subsequently,
542     outside the recursion, there was a failure, the code tried to back up into
543     the recursion. However, because of the way PCRE is implemented, this is not
544     possible, and the result was an incorrect result from the match.
546     In order to prevent this happening, the specification of recursion has
547     been changed so that all such subpatterns are automatically treated as
548     atomic groups. Thus, for example, (?R) is treated as if it were (?>(?R)).
550     4. I had overlooked the fact that, in some locales, there are characters for
551     which isalpha() is true but neither isupper() nor islower() are true. In
552     the fr_FR locale, for instance, the \xAA and \xBA characters (ordmasculine
553     and ordfeminine) are like this. This affected the treatment of \w and \W
554     when they appeared in character classes, but not when they appeared outside
555     a character class. The bit map for "word" characters is now created
556     separately from the results of isalnum() instead of just taking it from the
557     upper, lower, and digit maps. (Plus the underscore character, of course.)
559     5. The above bug also affected the handling of POSIX character classes such as
560     [[:alpha:]] and [[:alnum:]]. These do not have their own bit maps in PCRE's
561     permanent tables. Instead, the bit maps for such a class were previously
562     created as the appropriate unions of the upper, lower, and digit bitmaps.
563     Now they are created by subtraction from the [[:word:]] class, which has
564     its own bitmap.
566     6. The [[:blank:]] character class matches horizontal, but not vertical space.
567     It is created by subtracting the vertical space characters (\x09, \x0a,
568     \x0b, \x0c) from the [[:space:]] bitmap. Previously, however, the
569     subtraction was done in the overall bitmap for a character class, meaning
570     that a class such as [\x0c[:blank:]] was incorrect because \x0c would not
571     be recognized. This bug has been fixed.
573     7. Patches from the folks at Google:
575     (a) pcrecpp.cc: "to handle a corner case that may or may not happen in
576     real life, but is still worth protecting against".
578     (b) pcrecpp.cc: "corrects a bug when negative radixes are used with
579     regular expressions".
581     (c) pcre_scanner.cc: avoid use of std::count() because not all systems
582     have it.
584     (d) Split off pcrecpparg.h from pcrecpp.h and had the former built by
585     "configure" and the latter not, in order to fix a problem somebody had
586     with compiling the Arg class on HP-UX.
588     (e) Improve the error-handling of the C++ wrapper a little bit.
590     (f) New tests for checking recursion limiting.
592     8. The pcre_memmove() function, which is used only if the environment does not
593     have a standard memmove() function (and is therefore rarely compiled),
594     contained two bugs: (a) use of int instead of size_t, and (b) it was not
595     returning a result (though PCRE never actually uses the result).
597     9. In the POSIX regexec() interface, if nmatch is specified as a ridiculously
598     large number - greater than INT_MAX/(3*sizeof(int)) - REG_ESPACE is
599     returned instead of calling malloc() with an overflowing number that would
600     most likely cause subsequent chaos.
602     10. The debugging option of pcretest was not showing the NO_AUTO_CAPTURE flag.
604     11. The POSIX flag REG_NOSUB is now supported. When a pattern that was compiled
605     with this option is matched, the nmatch and pmatch options of regexec() are
606     ignored.
608     12. Added REG_UTF8 to the POSIX interface. This is not defined by POSIX, but is
609     provided in case anyone wants to the the POSIX interface with UTF-8
610     strings.
612     13. Added CXXLDFLAGS to the Makefile parameters to provide settings only on the
613     C++ linking (needed for some HP-UX environments).
615     14. Avoid compiler warnings in get_ucpname() when compiled without UCP support
616     (unused parameter) and in the pcre_printint() function (omitted "default"
617     switch label when the default is to do nothing).
619     15. Added some code to make it possible, when PCRE is compiled as a C++
620     library, to replace subject pointers for pcre_exec() with a smart pointer
621     class, thus making it possible to process discontinuous strings.
623     16. The two macros PCRE_EXPORT and PCRE_DATA_SCOPE are confusing, and perform
624     much the same function. They were added by different people who were trying
625     to make PCRE easy to compile on non-Unix systems. It has been suggested
626     that PCRE_EXPORT be abolished now that there is more automatic apparatus
627     for compiling on Windows systems. I have therefore replaced it with
628     PCRE_DATA_SCOPE. This is set automatically for Windows; if not set it
629     defaults to "extern" for C or "extern C" for C++, which works fine on
630     Unix-like systems. It is now possible to override the value of PCRE_DATA_
631     SCOPE with something explicit in config.h. In addition:
633     (a) pcreposix.h still had just "extern" instead of either of these macros;
634     I have replaced it with PCRE_DATA_SCOPE.
636     (b) Functions such as _pcre_xclass(), which are internal to the library,
637     but external in the C sense, all had PCRE_EXPORT in their definitions.
638     This is apparently wrong for the Windows case, so I have removed it.
639     (It makes no difference on Unix-like systems.)
641     17. Added a new limit, MATCH_LIMIT_RECURSION, which limits the depth of nesting
642     of recursive calls to match(). This is different to MATCH_LIMIT because
643     that limits the total number of calls to match(), not all of which increase
644     the depth of recursion. Limiting the recursion depth limits the amount of
645     stack (or heap if NO_RECURSE is set) that is used. The default can be set
646     when PCRE is compiled, and changed at run time. A patch from Google adds
647     this functionality to the C++ interface.
649     18. Changes to the handling of Unicode character properties:
651     (a) Updated the table to Unicode 4.1.0.
653     (b) Recognize characters that are not in the table as "Cn" (undefined).
655     (c) I revised the way the table is implemented to a much improved format
656     which includes recognition of ranges. It now supports the ranges that
657     are defined in UnicodeData.txt, and it also amalgamates other
658     characters into ranges. This has reduced the number of entries in the
659     table from around 16,000 to around 3,000, thus reducing its size
660     considerably. I realized I did not need to use a tree structure after
661     all - a binary chop search is just as efficient. Having reduced the
662     number of entries, I extended their size from 6 bytes to 8 bytes to
663     allow for more data.
665     (d) Added support for Unicode script names via properties such as \p{Han}.
667     19. In UTF-8 mode, a backslash followed by a non-Ascii character was not
668     matching that character.
670     20. When matching a repeated Unicode property with a minimum greater than zero,
671     (for example \pL{2,}), PCRE could look past the end of the subject if it
672     reached it while seeking the minimum number of characters. This could
673     happen only if some of the characters were more than one byte long, because
674     there is a check for at least the minimum number of bytes.
676     21. Refactored the implementation of \p and \P so as to be more general, to
677     allow for more different types of property in future. This has changed the
678     compiled form incompatibly. Anybody with saved compiled patterns that use
679     \p or \P will have to recompile them.
681     22. Added "Any" and "L&" to the supported property types.
683     23. Recognize \x{...} as a code point specifier, even when not in UTF-8 mode,
684     but give a compile time error if the value is greater than 0xff.
686     24. The man pages for pcrepartial, pcreprecompile, and pcre_compile2 were
687     accidentally not being installed or uninstalled.
689     25. The pcre.h file was built from pcre.h.in, but the only changes that were
690     made were to insert the current release number. This seemed silly, because
691     it made things harder for people building PCRE on systems that don't run
692     "configure". I have turned pcre.h into a distributed file, no longer built
693     by "configure", with the version identification directly included. There is
694     no longer a pcre.h.in file.
696     However, this change necessitated a change to the pcre-config script as
697     well. It is built from pcre-config.in, and one of the substitutions was the
698     release number. I have updated configure.ac so that ./configure now finds
699     the release number by grepping pcre.h.
701     26. Added the ability to run the tests under valgrind.
704 nigel 85 Version 6.4 05-Sep-05
705     ---------------------
707     1. Change 6.0/10/(l) to pcregrep introduced a bug that caused separator lines
708     "--" to be printed when multiple files were scanned, even when none of the
709     -A, -B, or -C options were used. This is not compatible with Gnu grep, so I
710     consider it to be a bug, and have restored the previous behaviour.
712     2. A couple of code tidies to get rid of compiler warnings.
714     3. The pcretest program used to cheat by referring to symbols in the library
715     whose names begin with _pcre_. These are internal symbols that are not
716     really supposed to be visible externally, and in some environments it is
717     possible to suppress them. The cheating is now confined to including
718     certain files from the library's source, which is a bit cleaner.
720     4. Renamed pcre.in as pcre.h.in to go with pcrecpp.h.in; it also makes the
721     file's purpose clearer.
723     5. Reorganized pcre_ucp_findchar().
726 nigel 83 Version 6.3 15-Aug-05
727     ---------------------
729     1. The file libpcre.pc.in did not have general read permission in the tarball.
731     2. There were some problems when building without C++ support:
733     (a) If C++ support was not built, "make install" and "make test" still
734     tried to test it.
736     (b) There were problems when the value of CXX was explicitly set. Some
737     changes have been made to try to fix these, and ...
739     (c) --disable-cpp can now be used to explicitly disable C++ support.
741     (d) The use of @CPP_OBJ@ directly caused a blank line preceded by a
742     backslash in a target when C++ was disabled. This confuses some
743     versions of "make", apparently. Using an intermediate variable solves
744     this. (Same for CPP_LOBJ.)
746     3. $(LINK_FOR_BUILD) now includes $(CFLAGS_FOR_BUILD) and $(LINK)
747     (non-Windows) now includes $(CFLAGS) because these flags are sometimes
748     necessary on certain architectures.
750     4. Added a setting of -export-symbols-regex to the link command to remove
751     those symbols that are exported in the C sense, but actually are local
752     within the library, and not documented. Their names all begin with
753     "_pcre_". This is not a perfect job, because (a) we have to except some
754     symbols that pcretest ("illegally") uses, and (b) the facility isn't always
755     available (and never for static libraries). I have made a note to try to
756     find a way round (a) in the future.
759 nigel 81 Version 6.2 01-Aug-05
760     ---------------------
762     1. There was no test for integer overflow of quantifier values. A construction
763     such as {1111111111111111} would give undefined results. What is worse, if
764     a minimum quantifier for a parenthesized subpattern overflowed and became
765     negative, the calculation of the memory size went wrong. This could have
766     led to memory overwriting.
768     2. Building PCRE using VPATH was broken. Hopefully it is now fixed.
770     3. Added "b" to the 2nd argument of fopen() in dftables.c, for non-Unix-like
771     operating environments where this matters.
773     4. Applied Giuseppe Maxia's patch to add additional features for controlling
774     PCRE options from within the C++ wrapper.
776     5. Named capturing subpatterns were not being correctly counted when a pattern
777     was compiled. This caused two problems: (a) If there were more than 100
778     such subpatterns, the calculation of the memory needed for the whole
779     compiled pattern went wrong, leading to an overflow error. (b) Numerical
780     back references of the form \12, where the number was greater than 9, were
781     not recognized as back references, even though there were sufficient
782     previous subpatterns.
784     6. Two minor patches to pcrecpp.cc in order to allow it to compile on older
785     versions of gcc, e.g. 2.95.4.
788 nigel 79 Version 6.1 21-Jun-05
789     ---------------------
791     1. There was one reference to the variable "posix" in pcretest.c that was not
792     surrounded by "#if !defined NOPOSIX".
794     2. Make it possible to compile pcretest without DFA support, UTF8 support, or
795     the cross-check on the old pcre_info() function, for the benefit of the
796     cut-down version of PCRE that is currently imported into Exim.
798     3. A (silly) pattern starting with (?i)(?-i) caused an internal space
799     allocation error. I've done the easy fix, which wastes 2 bytes for sensible
800     patterns that start (?i) but I don't think that matters. The use of (?i) is
801     just an example; this all applies to the other options as well.
803     4. Since libtool seems to echo the compile commands it is issuing, the output
804     from "make" can be reduced a bit by putting "@" in front of each libtool
805     compile command.
807     5. Patch from the folks at Google for configure.in to be a bit more thorough
808     in checking for a suitable C++ installation before trying to compile the
809     C++ stuff. This should fix a reported problem when a compiler was present,
810     but no suitable headers.
812     6. The man pages all had just "PCRE" as their title. I have changed them to
813     be the relevant file name. I have also arranged that these names are
814     retained in the file doc/pcre.txt, which is a concatenation in text format
815     of all the man pages except the little individual ones for each function.
817     7. The NON-UNIX-USE file had not been updated for the different set of source
818     files that come with release 6. I also added a few comments about the C++
819     wrapper.
822 nigel 77 Version 6.0 07-Jun-05
823     ---------------------
825     1. Some minor internal re-organization to help with my DFA experiments.
827     2. Some missing #ifdef SUPPORT_UCP conditionals in pcretest and printint that
828     didn't matter for the library itself when fully configured, but did matter
829     when compiling without UCP support, or within Exim, where the ucp files are
830     not imported.
832     3. Refactoring of the library code to split up the various functions into
833     different source modules. The addition of the new DFA matching code (see
834     below) to a single monolithic source would have made it really too
835     unwieldy, quite apart from causing all the code to be include in a
836     statically linked application, when only some functions are used. This is
837     relevant even without the DFA addition now that patterns can be compiled in
838     one application and matched in another.
840     The downside of splitting up is that there have to be some external
841     functions and data tables that are used internally in different modules of
842     the library but which are not part of the API. These have all had their
843     names changed to start with "_pcre_" so that they are unlikely to clash
844     with other external names.
846     4. Added an alternate matching function, pcre_dfa_exec(), which matches using
847     a different (DFA) algorithm. Although it is slower than the original
848     function, it does have some advantages for certain types of matching
849     problem.
851     5. Upgrades to pcretest in order to test the features of pcre_dfa_exec(),
852     including restarting after a partial match.
854     6. A patch for pcregrep that defines INVALID_FILE_ATTRIBUTES if it is not
855     defined when compiling for Windows was sent to me. I have put it into the
856     code, though I have no means of testing or verifying it.
858     7. Added the pcre_refcount() auxiliary function.
860     8. Added the PCRE_FIRSTLINE option. This constrains an unanchored pattern to
861     match before or at the first newline in the subject string. In pcretest,
862     the /f option on a pattern can be used to set this.
864     9. A repeated \w when used in UTF-8 mode with characters greater than 256
865     would behave wrongly. This has been present in PCRE since release 4.0.
867     10. A number of changes to the pcregrep command:
869     (a) Refactored how -x works; insert ^(...)$ instead of setting
870     PCRE_ANCHORED and checking the length, in preparation for adding
871     something similar for -w.
873     (b) Added the -w (match as a word) option.
875     (c) Refactored the way lines are read and buffered so as to have more
876     than one at a time available.
878     (d) Implemented a pcregrep test script.
880     (e) Added the -M (multiline match) option. This allows patterns to match
881     over several lines of the subject. The buffering ensures that at least
882     8K, or the rest of the document (whichever is the shorter) is available
883     for matching (and similarly the previous 8K for lookbehind assertions).
885     (f) Changed the --help output so that it now says
887     -w, --word-regex(p)
889     instead of two lines, one with "regex" and the other with "regexp"
890     because that confused at least one person since the short forms are the
891     same. (This required a bit of code, as the output is generated
892     automatically from a table. It wasn't just a text change.)
894     (g) -- can be used to terminate pcregrep options if the next thing isn't an
895     option but starts with a hyphen. Could be a pattern or a path name
896     starting with a hyphen, for instance.
898     (h) "-" can be given as a file name to represent stdin.
900     (i) When file names are being printed, "(standard input)" is used for
901     the standard input, for compatibility with GNU grep. Previously
902     "<stdin>" was used.
904     (j) The option --label=xxx can be used to supply a name to be used for
905     stdin when file names are being printed. There is no short form.
907     (k) Re-factored the options decoding logic because we are going to add
908     two more options that take data. Such options can now be given in four
909     different ways, e.g. "-fname", "-f name", "--file=name", "--file name".
911     (l) Added the -A, -B, and -C options for requesting that lines of context
912     around matches be printed.
914     (m) Added the -L option to print the names of files that do not contain
915     any matching lines, that is, the complement of -l.
917     (n) The return code is 2 if any file cannot be opened, but pcregrep does
918     continue to scan other files.
920     (o) The -s option was incorrectly implemented. For compatibility with other
921     greps, it now suppresses the error message for a non-existent or non-
922     accessible file (but not the return code). There is a new option called
923     -q that suppresses the output of matching lines, which was what -s was
924     previously doing.
926     (p) Added --include and --exclude options to specify files for inclusion
927     and exclusion when recursing.
929     11. The Makefile was not using the Autoconf-supported LDFLAGS macro properly.
930     Hopefully, it now does.
932     12. Missing cast in pcre_study().
934     13. Added an "uninstall" target to the makefile.
936     14. Replaced "extern" in the function prototypes in Makefile.in with
937     "PCRE_DATA_SCOPE", which defaults to 'extern' or 'extern "C"' in the Unix
938     world, but is set differently for Windows.
940     15. Added a second compiling function called pcre_compile2(). The only
941     difference is that it has an extra argument, which is a pointer to an
942     integer error code. When there is a compile-time failure, this is set
943     non-zero, in addition to the error test pointer being set to point to an
944     error message. The new argument may be NULL if no error number is required
945     (but then you may as well call pcre_compile(), which is now just a
946     wrapper). This facility is provided because some applications need a
947     numeric error indication, but it has also enabled me to tidy up the way
948     compile-time errors are handled in the POSIX wrapper.
950     16. Added VPATH=.libs to the makefile; this should help when building with one
951     prefix path and installing with another. (Or so I'm told by someone who
952     knows more about this stuff than I do.)
954     17. Added a new option, REG_DOTALL, to the POSIX function regcomp(). This
955     passes PCRE_DOTALL to the pcre_compile() function, making the "." character
956     match everything, including newlines. This is not POSIX-compatible, but
957     somebody wanted the feature. From pcretest it can be activated by using
958     both the P and the s flags.
960     18. AC_PROG_LIBTOOL appeared twice in Makefile.in. Removed one.
962     19. libpcre.pc was being incorrectly installed as executable.
964     20. A couple of places in pcretest check for end-of-line by looking for '\n';
965     it now also looks for '\r' so that it will work unmodified on Windows.
967     21. Added Google's contributed C++ wrapper to the distribution.
969     22. Added some untidy missing memory free() calls in pcretest, to keep
970     Electric Fence happy when testing.
974 nigel 75 Version 5.0 13-Sep-04
975     ---------------------
977     1. Internal change: literal characters are no longer packed up into items
978     containing multiple characters in a single byte-string. Each character
979     is now matched using a separate opcode. However, there may be more than one
980     byte in the character in UTF-8 mode.
982     2. The pcre_callout_block structure has two new fields: pattern_position and
983     next_item_length. These contain the offset in the pattern to the next match
984     item, and its length, respectively.
986     3. The PCRE_AUTO_CALLOUT option for pcre_compile() requests the automatic
987     insertion of callouts before each pattern item. Added the /C option to
988     pcretest to make use of this.
990     4. On the advice of a Windows user, the lines
992     #if defined(_WIN32) || defined(WIN32)
993     _setmode( _fileno( stdout ), 0x8000 );
994     #endif /* defined(_WIN32) || defined(WIN32) */
996     have been added to the source of pcretest. This apparently does useful
997     magic in relation to line terminators.
999     5. Changed "r" and "w" in the calls to fopen() in pcretest to "rb" and "wb"
1000     for the benefit of those environments where the "b" makes a difference.
1002     6. The icc compiler has the same options as gcc, but "configure" doesn't seem
1003     to know about it. I have put a hack into configure.in that adds in code
1004     to set GCC=yes if CC=icc. This seems to end up at a point in the
1005     generated configure script that is early enough to affect the setting of
1006     compiler options, which is what is needed, but I have no means of testing
1007     whether it really works. (The user who reported this had patched the
1008     generated configure script, which of course I cannot do.)
1010     LATER: After change 22 below (new libtool files), the configure script
1011     seems to know about icc (and also ecc). Therefore, I have commented out
1012     this hack in configure.in.
1014     7. Added support for pkg-config (2 patches were sent in).
1016     8. Negated POSIX character classes that used a combination of internal tables
1017     were completely broken. These were [[:^alpha:]], [[:^alnum:]], and
1018     [[:^ascii]]. Typically, they would match almost any characters. The other
1019     POSIX classes were not broken in this way.
1021     9. Matching the pattern "\b.*?" against "ab cd", starting at offset 1, failed
1022     to find the match, as PCRE was deluded into thinking that the match had to
1023     start at the start point or following a newline. The same bug applied to
1024     patterns with negative forward assertions or any backward assertions
1025     preceding ".*" at the start, unless the pattern required a fixed first
1026     character. This was a failing pattern: "(?!.bcd).*". The bug is now fixed.
1028     10. In UTF-8 mode, when moving forwards in the subject after a failed match
1029     starting at the last subject character, bytes beyond the end of the subject
1030     string were read.
1032     11. Renamed the variable "class" as "classbits" to make life easier for C++
1033     users. (Previously there was a macro definition, but it apparently wasn't
1034     enough.)
1036     12. Added the new field "tables" to the extra data so that tables can be passed
1037     in at exec time, or the internal tables can be re-selected. This allows
1038     a compiled regex to be saved and re-used at a later time by a different
1039     program that might have everything at different addresses.
1041     13. Modified the pcre-config script so that, when run on Solaris, it shows a
1042     -R library as well as a -L library.
1044     14. The debugging options of pcretest (-d on the command line or D on a
1045     pattern) showed incorrect output for anything following an extended class
1046     that contained multibyte characters and which was followed by a quantifier.
1048     15. Added optional support for general category Unicode character properties
1049     via the \p, \P, and \X escapes. Unicode property support implies UTF-8
1050     support. It adds about 90K to the size of the library. The meanings of the
1051     inbuilt class escapes such as \d and \s have NOT been changed.
1053     16. Updated pcredemo.c to include calls to free() to release the memory for the
1054     compiled pattern.
1056     17. The generated file chartables.c was being created in the source directory
1057     instead of in the building directory. This caused the build to fail if the
1058     source directory was different from the building directory, and was
1059     read-only.
1061     18. Added some sample Win commands from Mark Tetrode into the NON-UNIX-USE
1062     file. No doubt somebody will tell me if they don't make sense... Also added
1063     Dan Mooney's comments about building on OpenVMS.
1065     19. Added support for partial matching via the PCRE_PARTIAL option for
1066     pcre_exec() and the \P data escape in pcretest.
1068     20. Extended pcretest with 3 new pattern features:
1070     (i) A pattern option of the form ">rest-of-line" causes pcretest to
1071     write the compiled pattern to the file whose name is "rest-of-line".
1072     This is a straight binary dump of the data, with the saved pointer to
1073     the character tables forced to be NULL. The study data, if any, is
1074     written too. After writing, pcretest reads a new pattern.
1076     (ii) If, instead of a pattern, "<rest-of-line" is given, pcretest reads a
1077     compiled pattern from the given file. There must not be any
1078     occurrences of "<" in the file name (pretty unlikely); if there are,
1079     pcretest will instead treat the initial "<" as a pattern delimiter.
1080     After reading in the pattern, pcretest goes on to read data lines as
1081     usual.
1083     (iii) The F pattern option causes pcretest to flip the bytes in the 32-bit
1084     and 16-bit fields in a compiled pattern, to simulate a pattern that
1085     was compiled on a host of opposite endianness.
1087     21. The pcre-exec() function can now cope with patterns that were compiled on
1088     hosts of opposite endianness, with this restriction:
1090     As for any compiled expression that is saved and used later, the tables
1091     pointer field cannot be preserved; the extra_data field in the arguments
1092     to pcre_exec() should be used to pass in a tables address if a value
1093     other than the default internal tables were used at compile time.
1095     22. Calling pcre_exec() with a negative value of the "ovecsize" parameter is
1096     now diagnosed as an error. Previously, most of the time, a negative number
1097     would have been treated as zero, but if in addition "ovector" was passed as
1098     NULL, a crash could occur.
1100     23. Updated the files ltmain.sh, config.sub, config.guess, and aclocal.m4 with
1101     new versions from the libtool 1.5 distribution (the last one is a copy of
1102     a file called libtool.m4). This seems to have fixed the need to patch
1103     "configure" to support Darwin 1.3 (which I used to do). However, I still
1104     had to patch ltmain.sh to ensure that ${SED} is set (it isn't on my
1105     workstation).
1107     24. Changed the PCRE licence to be the more standard "BSD" licence.
1110 nigel 73 Version 4.5 01-Dec-03
1111     ---------------------
1113     1. There has been some re-arrangement of the code for the match() function so
1114     that it can be compiled in a version that does not call itself recursively.
1115     Instead, it keeps those local variables that need separate instances for
1116     each "recursion" in a frame on the heap, and gets/frees frames whenever it
1117     needs to "recurse". Keeping track of where control must go is done by means
1118     of setjmp/longjmp. The whole thing is implemented by a set of macros that
1119     hide most of the details from the main code, and operates only if
1120     NO_RECURSE is defined while compiling pcre.c. If PCRE is built using the
1121     "configure" mechanism, "--disable-stack-for-recursion" turns on this way of
1122     operating.
1124     To make it easier for callers to provide specially tailored get/free
1125     functions for this usage, two new functions, pcre_stack_malloc, and
1126     pcre_stack_free, are used. They are always called in strict stacking order,
1127     and the size of block requested is always the same.
1129     The PCRE_CONFIG_STACKRECURSE info parameter can be used to find out whether
1130     PCRE has been compiled to use the stack or the heap for recursion. The
1131     -C option of pcretest uses this to show which version is compiled.
1133     A new data escape \S, is added to pcretest; it causes the amounts of store
1134     obtained and freed by both kinds of malloc/free at match time to be added
1135     to the output.
1137     2. Changed the locale test to use "fr_FR" instead of "fr" because that's
1138     what's available on my current Linux desktop machine.
1140     3. When matching a UTF-8 string, the test for a valid string at the start has
1141     been extended. If start_offset is not zero, PCRE now checks that it points
1142     to a byte that is the start of a UTF-8 character. If not, it returns
1143     PCRE_ERROR_BADUTF8_OFFSET (-11). Note: the whole string is still checked;
1144     this is necessary because there may be backward assertions in the pattern.
1145     When matching the same subject several times, it may save resources to use
1146     PCRE_NO_UTF8_CHECK on all but the first call if the string is long.
1148     4. The code for checking the validity of UTF-8 strings has been tightened so
1149     that it rejects (a) strings containing 0xfe or 0xff bytes and (b) strings
1150     containing "overlong sequences".
1152     5. Fixed a bug (appearing twice) that I could not find any way of exploiting!
1153     I had written "if ((digitab[*p++] && chtab_digit) == 0)" where the "&&"
1154     should have been "&", but it just so happened that all the cases this let
1155     through by mistake were picked up later in the function.
1157     6. I had used a variable called "isblank" - this is a C99 function, causing
1158     some compilers to warn. To avoid this, I renamed it (as "blankclass").
1160     7. Cosmetic: (a) only output another newline at the end of pcretest if it is
1161     prompting; (b) run "./pcretest /dev/null" at the start of the test script
1162     so the version is shown; (c) stop "make test" echoing "./RunTest".
1164     8. Added patches from David Burgess to enable PCRE to run on EBCDIC systems.
1166     9. The prototype for memmove() for systems that don't have it was using
1167     size_t, but the inclusion of the header that defines size_t was later. I've
1168     moved the #includes for the C headers earlier to avoid this.
1170     10. Added some adjustments to the code to make it easier to compiler on certain
1171     special systems:
1173     (a) Some "const" qualifiers were missing.
1174     (b) Added the macro EXPORT before all exported functions; by default this
1175     is defined to be empty.
1176     (c) Changed the dftables auxiliary program (that builds chartables.c) so
1177     that it reads its output file name as an argument instead of writing
1178     to the standard output and assuming this can be redirected.
1180     11. In UTF-8 mode, if a recursive reference (e.g. (?1)) followed a character
1181     class containing characters with values greater than 255, PCRE compilation
1182     went into a loop.
1184     12. A recursive reference to a subpattern that was within another subpattern
1185     that had a minimum quantifier of zero caused PCRE to crash. For example,
1186     (x(y(?2))z)? provoked this bug with a subject that got as far as the
1187     recursion. If the recursively-called subpattern itself had a zero repeat,
1188     that was OK.
1190     13. In pcretest, the buffer for reading a data line was set at 30K, but the
1191     buffer into which it was copied (for escape processing) was still set at
1192     1024, so long lines caused crashes.
1194     14. A pattern such as /[ab]{1,3}+/ failed to compile, giving the error
1195     "internal error: code overflow...". This applied to any character class
1196     that was followed by a possessive quantifier.
1198     15. Modified the Makefile to add libpcre.la as a prerequisite for
1199     libpcreposix.la because I was told this is needed for a parallel build to
1200     work.
1202     16. If a pattern that contained .* following optional items at the start was
1203     studied, the wrong optimizing data was generated, leading to matching
1204     errors. For example, studying /[ab]*.*c/ concluded, erroneously, that any
1205     matching string must start with a or b or c. The correct conclusion for
1206     this pattern is that a match can start with any character.
1209 nigel 71 Version 4.4 13-Aug-03
1210     ---------------------
1212     1. In UTF-8 mode, a character class containing characters with values between
1213     127 and 255 was not handled correctly if the compiled pattern was studied.
1214     In fixing this, I have also improved the studying algorithm for such
1215     classes (slightly).
1217     2. Three internal functions had redundant arguments passed to them. Removal
1218     might give a very teeny performance improvement.
1220     3. Documentation bug: the value of the capture_top field in a callout is *one
1221     more than* the number of the hightest numbered captured substring.
1223     4. The Makefile linked pcretest and pcregrep with -lpcre, which could result
1224     in incorrectly linking with a previously installed version. They now link
1225     explicitly with libpcre.la.
1227     5. configure.in no longer needs to recognize Cygwin specially.
1229     6. A problem in pcre.in for Windows platforms is fixed.
1231     7. If a pattern was successfully studied, and the -d (or /D) flag was given to
1232     pcretest, it used to include the size of the study block as part of its
1233     output. Unfortunately, the structure contains a field that has a different
1234     size on different hardware architectures. This meant that the tests that
1235     showed this size failed. As the block is currently always of a fixed size,
1236     this information isn't actually particularly useful in pcretest output, so
1237     I have just removed it.
1239     8. Three pre-processor statements accidentally did not start in column 1.
1240     Sadly, there are *still* compilers around that complain, even though
1241     standard C has not required this for well over a decade. Sigh.
1243     9. In pcretest, the code for checking callouts passed small integers in the
1244     callout_data field, which is a void * field. However, some picky compilers
1245     complained about the casts involved for this on 64-bit systems. Now
1246     pcretest passes the address of the small integer instead, which should get
1247     rid of the warnings.
1249     10. By default, when in UTF-8 mode, PCRE now checks for valid UTF-8 strings at
1250     both compile and run time, and gives an error if an invalid UTF-8 sequence
1251     is found. There is a option for disabling this check in cases where the
1252     string is known to be correct and/or the maximum performance is wanted.
1254     11. In response to a bug report, I changed one line in Makefile.in from
1256     -Wl,--out-implib,.libs/lib@WIN_PREFIX@pcreposix.dll.a \
1257     to
1258     -Wl,--out-implib,.libs/@WIN_PREFIX@libpcreposix.dll.a \
1260     to look similar to other lines, but I have no way of telling whether this
1261     is the right thing to do, as I do not use Windows. No doubt I'll get told
1262     if it's wrong...
1265 nigel 69 Version 4.3 21-May-03
1266     ---------------------
1268     1. Two instances of @WIN_PREFIX@ omitted from the Windows targets in the
1269     Makefile.
1271     2. Some refactoring to improve the quality of the code:
1273     (i) The utf8_table... variables are now declared "const".
1275     (ii) The code for \cx, which used the "case flipping" table to upper case
1276     lower case letters, now just substracts 32. This is ASCII-specific,
1277     but the whole concept of \cx is ASCII-specific, so it seems
1278     reasonable.
1280     (iii) PCRE was using its character types table to recognize decimal and
1281     hexadecimal digits in the pattern. This is silly, because it handles
1282     only 0-9, a-f, and A-F, but the character types table is locale-
1283     specific, which means strange things might happen. A private
1284     table is now used for this - though it costs 256 bytes, a table is
1285     much faster than multiple explicit tests. Of course, the standard
1286     character types table is still used for matching digits in subject
1287     strings against \d.
1289     (iv) Strictly, the identifier ESC_t is reserved by POSIX (all identifiers
1290     ending in _t are). So I've renamed it as ESC_tee.
1292     3. The first argument for regexec() in the POSIX wrapper should have been
1293     defined as "const".
1295     4. Changed pcretest to use malloc() for its buffers so that they can be
1296     Electric Fenced for debugging.
1298     5. There were several places in the code where, in UTF-8 mode, PCRE would try
1299     to read one or more bytes before the start of the subject string. Often this
1300     had no effect on PCRE's behaviour, but in some circumstances it could
1301     provoke a segmentation fault.
1303     6. A lookbehind at the start of a pattern in UTF-8 mode could also cause PCRE
1304     to try to read one or more bytes before the start of the subject string.
1306     7. A lookbehind in a pattern matched in non-UTF-8 mode on a PCRE compiled with
1307     UTF-8 support could misbehave in various ways if the subject string
1308     contained bytes with the 0x80 bit set and the 0x40 bit unset in a lookbehind
1309     area. (PCRE was not checking for the UTF-8 mode flag, and trying to move
1310     back over UTF-8 characters.)
1313 nigel 67 Version 4.2 14-Apr-03
1314     ---------------------
1316     1. Typo "#if SUPPORT_UTF8" instead of "#ifdef SUPPORT_UTF8" fixed.
1318     2. Changes to the building process, supplied by Ronald Landheer-Cieslak
1319     [ON_WINDOWS]: new variable, "#" on non-Windows platforms
1320     [NOT_ON_WINDOWS]: new variable, "#" on Windows platforms
1321     [WIN_PREFIX]: new variable, "cyg" for Cygwin
1322     * Makefile.in: use autoconf substitution for OBJEXT, EXEEXT, BUILD_OBJEXT
1323     and BUILD_EXEEXT
1324     Note: automatic setting of the BUILD variables is not yet working
1325     set CPPFLAGS and BUILD_CPPFLAGS (but don't use yet) - should be used at
1326     compile-time but not at link-time
1327     [LINK]: use for linking executables only
1328     make different versions for Windows and non-Windows
1329     [LINKLIB]: new variable, copy of UNIX-style LINK, used for linking
1330     libraries
1331     [LINK_FOR_BUILD]: new variable
1332     [OBJEXT]: use throughout
1333     [EXEEXT]: use throughout
1334     <winshared>: new target
1335     <wininstall>: new target
1336     <dftables.o>: use native compiler
1337     <dftables>: use native linker
1338     <install>: handle Windows platform correctly
1339     <clean>: ditto
1340     <check>: ditto
1341     copy DLL to top builddir before testing
1343     As part of these changes, -no-undefined was removed again. This was reported
1344     to give trouble on HP-UX 11.0, so getting rid of it seems like a good idea
1345     in any case.
1347     3. Some tidies to get rid of compiler warnings:
1349     . In the match_data structure, match_limit was an unsigned long int, whereas
1350     match_call_count was an int. I've made them both unsigned long ints.
1352     . In pcretest the fact that a const uschar * doesn't automatically cast to
1353     a void * provoked a warning.
1355     . Turning on some more compiler warnings threw up some "shadow" variables
1356     and a few more missing casts.
1358     4. If PCRE was complied with UTF-8 support, but called without the PCRE_UTF8
1359     option, a class that contained a single character with a value between 128
1360     and 255 (e.g. /[\xFF]/) caused PCRE to crash.
1362     5. If PCRE was compiled with UTF-8 support, but called without the PCRE_UTF8
1363     option, a class that contained several characters, but with at least one
1364     whose value was between 128 and 255 caused PCRE to crash.
1367 nigel 65 Version 4.1 12-Mar-03
1368     ---------------------
1369 nigel 63
1370 nigel 65 1. Compiling with gcc -pedantic found a couple of places where casts were
1371     needed, and a string in dftables.c that was longer than standard compilers are
1372     required to support.
1374     2. Compiling with Sun's compiler found a few more places where the code could
1375     be tidied up in order to avoid warnings.
1377     3. The variables for cross-compiling were called HOST_CC and HOST_CFLAGS; the
1378     first of these names is deprecated in the latest Autoconf in favour of the name
1379     CC_FOR_BUILD, because "host" is typically used to mean the system on which the
1380     compiled code will be run. I can't find a reference for HOST_CFLAGS, but by
1381     analogy I have changed it to CFLAGS_FOR_BUILD.
1383     4. Added -no-undefined to the linking command in the Makefile, because this is
1384     apparently helpful for Windows. To make it work, also added "-L. -lpcre" to the
1385     linking step for the pcreposix library.
1387     5. PCRE was failing to diagnose the case of two named groups with the same
1388     name.
1390     6. A problem with one of PCRE's optimizations was discovered. PCRE remembers a
1391     literal character that is needed in the subject for a match, and scans along to
1392     ensure that it is present before embarking on the full matching process. This
1393     saves time in cases of nested unlimited repeats that are never going to match.
1394     Problem: the scan can take a lot of time if the subject is very long (e.g.
1395     megabytes), thus penalizing straightforward matches. It is now done only if the
1396     amount of subject to be scanned is less than 1000 bytes.
1398     7. A lesser problem with the same optimization is that it was recording the
1399     first character of an anchored pattern as "needed", thus provoking a search
1400     right along the subject, even when the first match of the pattern was going to
1401     fail. The "needed" character is now not set for anchored patterns, unless it
1402     follows something in the pattern that is of non-fixed length. Thus, it still
1403     fulfils its original purpose of finding quick non-matches in cases of nested
1404     unlimited repeats, but isn't used for simple anchored patterns such as /^abc/.
1407     Version 4.0 17-Feb-03
1408     ---------------------
1410 nigel 63 1. If a comment in an extended regex that started immediately after a meta-item
1411     extended to the end of string, PCRE compiled incorrect data. This could lead to
1412     all kinds of weird effects. Example: /#/ was bad; /()#/ was bad; /a#/ was not.
1414     2. Moved to autoconf 2.53 and libtool 1.4.2.
1416     3. Perl 5.8 no longer needs "use utf8" for doing UTF-8 things. Consequently,
1417     the special perltest8 script is no longer needed - all the tests can be run
1418     from a single perltest script.
1420     4. From 5.004, Perl has not included the VT character (0x0b) in the set defined
1421     by \s. It has now been removed in PCRE. This means it isn't recognized as
1422     whitespace in /x regexes too, which is the same as Perl. Note that the POSIX
1423     class [:space:] *does* include VT, thereby creating a mess.
1425     5. Added the class [:blank:] (a GNU extension from Perl 5.8) to match only
1426     space and tab.
1428     6. Perl 5.005 was a long time ago. It's time to amalgamate the tests that use
1429     its new features into the main test script, reducing the number of scripts.
1431     7. Perl 5.8 has changed the meaning of patterns like /a(?i)b/. Earlier versions
1432     were backward compatible, and made the (?i) apply to the whole pattern, as if
1433     /i were given. Now it behaves more logically, and applies the option setting
1434     only to what follows. PCRE has been changed to follow suit. However, if it
1435     finds options settings right at the start of the pattern, it extracts them into
1436     the global options, as before. Thus, they show up in the info data.
1438     8. Added support for the \Q...\E escape sequence. Characters in between are
1439     treated as literals. This is slightly different from Perl in that $ and @ are
1440     also handled as literals inside the quotes. In Perl, they will cause variable
1441     interpolation. Note the following examples:
1443     Pattern PCRE matches Perl matches
1445     \Qabc$xyz\E abc$xyz abc followed by the contents of $xyz
1446     \Qabc\$xyz\E abc\$xyz abc\$xyz
1447     \Qabc\E\$\Qxyz\E abc$xyz abc$xyz
1449     For compatibility with Perl, \Q...\E sequences are recognized inside character
1450     classes as well as outside them.
1452     9. Re-organized 3 code statements in pcretest to avoid "overflow in
1453     floating-point constant arithmetic" warnings from a Microsoft compiler. Added a
1454     (size_t) cast to one statement in pcretest and one in pcreposix to avoid
1455     signed/unsigned warnings.
1457     10. SunOS4 doesn't have strtoul(). This was used only for unpicking the -o
1458     option for pcretest, so I've replaced it by a simple function that does just
1459     that job.
1461     11. pcregrep was ending with code 0 instead of 2 for the commands "pcregrep" or
1462     "pcregrep -".
1464     12. Added "possessive quantifiers" ?+, *+, ++, and {,}+ which come from Sun's
1465     Java package. This provides some syntactic sugar for simple cases of what my
1466     documentation calls "once-only subpatterns". A pattern such as x*+ is the same
1467     as (?>x*). In other words, if what is inside (?>...) is just a single repeated
1468     item, you can use this simplified notation. Note that only makes sense with
1469     greedy quantifiers. Consequently, the use of the possessive quantifier forces
1470     greediness, whatever the setting of the PCRE_UNGREEDY option.
1472     13. A change of greediness default within a pattern was not taking effect at
1473     the current level for patterns like /(b+(?U)a+)/. It did apply to parenthesized
1474     subpatterns that followed. Patterns like /b+(?U)a+/ worked because the option
1475     was abstracted outside.
1477     14. PCRE now supports the \G assertion. It is true when the current matching
1478     position is at the start point of the match. This differs from \A when the
1479     starting offset is non-zero. Used with the /g option of pcretest (or similar
1480     code), it works in the same way as it does for Perl's /g option. If all
1481     alternatives of a regex begin with \G, the expression is anchored to the start
1482     match position, and the "anchored" flag is set in the compiled expression.
1484     15. Some bugs concerning the handling of certain option changes within patterns
1485     have been fixed. These applied to options other than (?ims). For example,
1486     "a(?x: b c )d" did not match "XabcdY" but did match "Xa b c dY". It should have
1487     been the other way round. Some of this was related to change 7 above.
1489     16. PCRE now gives errors for /[.x.]/ and /[=x=]/ as unsupported POSIX
1490     features, as Perl does. Previously, PCRE gave the warnings only for /[[.x.]]/
1491     and /[[=x=]]/. PCRE now also gives an error for /[:name:]/ because it supports
1492     POSIX classes only within a class (e.g. /[[:alpha:]]/).
1494     17. Added support for Perl's \C escape. This matches one byte, even in UTF8
1495     mode. Unlike ".", it always matches newline, whatever the setting of
1496     PCRE_DOTALL. However, PCRE does not permit \C to appear in lookbehind
1497     assertions. Perl allows it, but it doesn't (in general) work because it can't
1498     calculate the length of the lookbehind. At least, that's the case for Perl
1499     5.8.0 - I've been told they are going to document that it doesn't work in
1500     future.
1502     18. Added an error diagnosis for escapes that PCRE does not support: these are
1503     \L, \l, \N, \P, \p, \U, \u, and \X.
1505     19. Although correctly diagnosing a missing ']' in a character class, PCRE was
1506     reading past the end of the pattern in cases such as /[abcd/.
1508     20. PCRE was getting more memory than necessary for patterns with classes that
1509     contained both POSIX named classes and other characters, e.g. /[[:space:]abc/.
1511     21. Added some code, conditional on #ifdef VPCOMPAT, to make life easier for
1512     compiling PCRE for use with Virtual Pascal.
1514     22. Small fix to the Makefile to make it work properly if the build is done
1515     outside the source tree.
1517     23. Added a new extension: a condition to go with recursion. If a conditional
1518     subpattern starts with (?(R) the "true" branch is used if recursion has
1519     happened, whereas the "false" branch is used only at the top level.
1521     24. When there was a very long string of literal characters (over 255 bytes
1522     without UTF support, over 250 bytes with UTF support), the computation of how
1523     much memory was required could be incorrect, leading to segfaults or other
1524     strange effects.
1526     25. PCRE was incorrectly assuming anchoring (either to start of subject or to
1527     start of line for a non-DOTALL pattern) when a pattern started with (.*) and
1528     there was a subsequent back reference to those brackets. This meant that, for
1529     example, /(.*)\d+\1/ failed to match "abc123bc". Unfortunately, it isn't
1530     possible to check for precisely this case. All we can do is abandon the
1531     optimization if .* occurs inside capturing brackets when there are any back
1532     references whatsoever. (See below for a better fix that came later.)
1534     26. The handling of the optimization for finding the first character of a
1535     non-anchored pattern, and for finding a character that is required later in the
1536     match were failing in some cases. This didn't break the matching; it just
1537     failed to optimize when it could. The way this is done has been re-implemented.
1539     27. Fixed typo in error message for invalid (?R item (it said "(?p").
1541     28. Added a new feature that provides some of the functionality that Perl
1542     provides with (?{...}). The facility is termed a "callout". The way it is done
1543     in PCRE is for the caller to provide an optional function, by setting
1544     pcre_callout to its entry point. Like pcre_malloc and pcre_free, this is a
1545     global variable. By default it is unset, which disables all calling out. To get
1546     the function called, the regex must include (?C) at appropriate points. This
1547     is, in fact, equivalent to (?C0), and any number <= 255 may be given with (?C).
1548     This provides a means of identifying different callout points. When PCRE
1549     reaches such a point in the regex, if pcre_callout has been set, the external
1550     function is called. It is provided with data in a structure called
1551     pcre_callout_block, which is defined in pcre.h. If the function returns 0,
1552     matching continues; if it returns a non-zero value, the match at the current
1553     point fails. However, backtracking will occur if possible. [This was changed
1554     later and other features added - see item 49 below.]
1556     29. pcretest is upgraded to test the callout functionality. It provides a
1557     callout function that displays information. By default, it shows the start of
1558     the match and the current position in the text. There are some new data escapes
1559     to vary what happens:
1561     \C+ in addition, show current contents of captured substrings
1562     \C- do not supply a callout function
1563     \C!n return 1 when callout number n is reached
1564     \C!n!m return 1 when callout number n is reached for the mth time
1566     30. If pcregrep was called with the -l option and just a single file name, it
1567     output "<stdin>" if a match was found, instead of the file name.
1569     31. Improve the efficiency of the POSIX API to PCRE. If the number of capturing
1570     slots is less than POSIX_MALLOC_THRESHOLD, use a block on the stack to pass to
1571     pcre_exec(). This saves a malloc/free per call. The default value of
1572     POSIX_MALLOC_THRESHOLD is 10; it can be changed by --with-posix-malloc-threshold
1573     when configuring.
1575     32. The default maximum size of a compiled pattern is 64K. There have been a
1576     few cases of people hitting this limit. The code now uses macros to handle the
1577     storing of links as offsets within the compiled pattern. It defaults to 2-byte
1578     links, but this can be changed to 3 or 4 bytes by --with-link-size when
1579     configuring. Tests 2 and 5 work only with 2-byte links because they output
1580     debugging information about compiled patterns.
1582     33. Internal code re-arrangements:
1584     (a) Moved the debugging function for printing out a compiled regex into
1585     its own source file (printint.c) and used #include to pull it into
1586     pcretest.c and, when DEBUG is defined, into pcre.c, instead of having two
1587     separate copies.
1589     (b) Defined the list of op-code names for debugging as a macro in
1590     internal.h so that it is next to the definition of the opcodes.
1592     (c) Defined a table of op-code lengths for simpler skipping along compiled
1593     code. This is again a macro in internal.h so that it is next to the
1594     definition of the opcodes.
1596     34. Added support for recursive calls to individual subpatterns, along the
1597     lines of Robin Houston's patch (but implemented somewhat differently).
1599     35. Further mods to the Makefile to help Win32. Also, added code to pcregrep to
1600     allow it to read and process whole directories in Win32. This code was
1601     contributed by Lionel Fourquaux; it has not been tested by me.
1603     36. Added support for named subpatterns. The Python syntax (?P<name>...) is
1604     used to name a group. Names consist of alphanumerics and underscores, and must
1605     be unique. Back references use the syntax (?P=name) and recursive calls use
1606     (?P>name) which is a PCRE extension to the Python extension. Groups still have
1607     numbers. The function pcre_fullinfo() can be used after compilation to extract
1608     a name/number map. There are three relevant calls:
1610     PCRE_INFO_NAMEENTRYSIZE yields the size of each entry in the map
1611     PCRE_INFO_NAMECOUNT yields the number of entries
1612     PCRE_INFO_NAMETABLE yields a pointer to the map.
1614     The map is a vector of fixed-size entries. The size of each entry depends on
1615     the length of the longest name used. The first two bytes of each entry are the
1616     group number, most significant byte first. There follows the corresponding
1617     name, zero terminated. The names are in alphabetical order.
1619     37. Make the maximum literal string in the compiled code 250 for the non-UTF-8
1620     case instead of 255. Making it the same both with and without UTF-8 support
1621     means that the same test output works with both.
1623     38. There was a case of malloc(0) in the POSIX testing code in pcretest. Avoid
1624     calling malloc() with a zero argument.
1626     39. Change 25 above had to resort to a heavy-handed test for the .* anchoring
1627     optimization. I've improved things by keeping a bitmap of backreferences with
1628     numbers 1-31 so that if .* occurs inside capturing brackets that are not in
1629     fact referenced, the optimization can be applied. It is unlikely that a
1630     relevant occurrence of .* (i.e. one which might indicate anchoring or forcing
1631     the match to follow \n) will appear inside brackets with a number greater than
1632     31, but if it does, any back reference > 31 suppresses the optimization.
1634     40. Added a new compile-time option PCRE_NO_AUTO_CAPTURE. This has the effect
1635     of disabling numbered capturing parentheses. Any opening parenthesis that is
1636     not followed by ? behaves as if it were followed by ?: but named parentheses
1637     can still be used for capturing (and they will acquire numbers in the usual
1638     way).
1640     41. Redesigned the return codes from the match() function into yes/no/error so
1641     that errors can be passed back from deep inside the nested calls. A malloc
1642     failure while inside a recursive subpattern call now causes the
1643     PCRE_ERROR_NOMEMORY return instead of quietly going wrong.
1645     42. It is now possible to set a limit on the number of times the match()
1646     function is called in a call to pcre_exec(). This facility makes it possible to
1647     limit the amount of recursion and backtracking, though not in a directly
1648     obvious way, because the match() function is used in a number of different
1649     circumstances. The count starts from zero for each position in the subject
1650     string (for non-anchored patterns). The default limit is, for compatibility, a
1651     large number, namely 10 000 000. You can change this in two ways:
1653     (a) When configuring PCRE before making, you can use --with-match-limit=n
1654     to set a default value for the compiled library.
1656     (b) For each call to pcre_exec(), you can pass a pcre_extra block in which
1657     a different value is set. See 45 below.
1659     If the limit is exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT.
1661     43. Added a new function pcre_config(int, void *) to enable run-time extraction
1662     of things that can be changed at compile time. The first argument specifies
1663     what is wanted and the second points to where the information is to be placed.
1664     The current list of available information is:
1668     The output is an integer that is set to one if UTF-8 support is available;
1669     otherwise it is set to zero.
1673     The output is an integer that it set to the value of the code that is used for
1674     newline. It is either LF (10) or CR (13).
1678     The output is an integer that contains the number of bytes used for internal
1679     linkage in compiled expressions. The value is 2, 3, or 4. See item 32 above.
1683     The output is an integer that contains the threshold above which the POSIX
1684     interface uses malloc() for output vectors. See item 31 above.
1688     The output is an unsigned integer that contains the default limit of the number
1689     of match() calls in a pcre_exec() execution. See 42 above.
1691     44. pcretest has been upgraded by the addition of the -C option. This causes it
1692     to extract all the available output from the new pcre_config() function, and to
1693     output it. The program then exits immediately.
1695     45. A need has arisen to pass over additional data with calls to pcre_exec() in
1696     order to support additional features. One way would have been to define
1697     pcre_exec2() (for example) with extra arguments, but this would not have been
1698     extensible, and would also have required all calls to the original function to
1699     be mapped to the new one. Instead, I have chosen to extend the mechanism that
1700     is used for passing in "extra" data from pcre_study().
1702     The pcre_extra structure is now exposed and defined in pcre.h. It currently
1703     contains the following fields:
1705     flags a bitmap indicating which of the following fields are set
1706     study_data opaque data from pcre_study()
1707     match_limit a way of specifying a limit on match() calls for a specific
1708     call to pcre_exec()
1709     callout_data data for callouts (see 49 below)
1711     The flag bits are also defined in pcre.h, and are
1717     The pcre_study() function now returns one of these new pcre_extra blocks, with
1718     the actual study data pointed to by the study_data field, and the
1719     PCRE_EXTRA_STUDY_DATA flag set. This can be passed directly to pcre_exec() as
1720     before. That is, this change is entirely upwards-compatible and requires no
1721     change to existing code.
1723     If you want to pass in additional data to pcre_exec(), you can either place it
1724     in a pcre_extra block provided by pcre_study(), or create your own pcre_extra
1725     block.
1727     46. pcretest has been extended to test the PCRE_EXTRA_MATCH_LIMIT feature. If a
1728     data string contains the escape sequence \M, pcretest calls pcre_exec() several
1729     times with different match limits, until it finds the minimum value needed for
1730     pcre_exec() to complete. The value is then output. This can be instructive; for
1731     most simple matches the number is quite small, but for pathological cases it
1732     gets very large very quickly.
1734     47. There's a new option for pcre_fullinfo() called PCRE_INFO_STUDYSIZE. It
1735     returns the size of the data block pointed to by the study_data field in a
1736     pcre_extra block, that is, the value that was passed as the argument to
1737     pcre_malloc() when PCRE was getting memory in which to place the information
1738     created by pcre_study(). The fourth argument should point to a size_t variable.
1739     pcretest has been extended so that this information is shown after a successful
1740     pcre_study() call when information about the compiled regex is being displayed.
1742     48. Cosmetic change to Makefile: there's no need to have / after $(DESTDIR)
1743     because what follows is always an absolute path. (Later: it turns out that this
1744     is more than cosmetic for MinGW, because it doesn't like empty path
1745     components.)
1747     49. Some changes have been made to the callout feature (see 28 above):
1749     (i) A callout function now has three choices for what it returns:
1751     0 => success, carry on matching
1752     > 0 => failure at this point, but backtrack if possible
1753     < 0 => serious error, return this value from pcre_exec()
1755     Negative values should normally be chosen from the set of PCRE_ERROR_xxx
1756     values. In particular, returning PCRE_ERROR_NOMATCH forces a standard
1757     "match failed" error. The error number PCRE_ERROR_CALLOUT is reserved for
1758     use by callout functions. It will never be used by PCRE itself.
1760     (ii) The pcre_extra structure (see 45 above) has a void * field called
1761     callout_data, with corresponding flag bit PCRE_EXTRA_CALLOUT_DATA. The
1762     pcre_callout_block structure has a field of the same name. The contents of
1763     the field passed in the pcre_extra structure are passed to the callout
1764     function in the corresponding field in the callout block. This makes it
1765     easier to use the same callout-containing regex from multiple threads. For
1766     testing, the pcretest program has a new data escape
1768     \C*n pass the number n (may be negative) as callout_data
1770     If the callout function in pcretest receives a non-zero value as
1771     callout_data, it returns that value.
1773     50. Makefile wasn't handling CFLAGS properly when compiling dftables. Also,
1774     there were some redundant $(CFLAGS) in commands that are now specified as
1775     $(LINK), which already includes $(CFLAGS).
1777     51. Extensions to UTF-8 support are listed below. These all apply when (a) PCRE
1778     has been compiled with UTF-8 support *and* pcre_compile() has been compiled
1779     with the PCRE_UTF8 flag. Patterns that are compiled without that flag assume
1780     one-byte characters throughout. Note that case-insensitive matching applies
1781     only to characters whose values are less than 256. PCRE doesn't support the
1782     notion of cases for higher-valued characters.
1784     (i) A character class whose characters are all within 0-255 is handled as
1785     a bit map, and the map is inverted for negative classes. Previously, a
1786     character > 255 always failed to match such a class; however it should
1787     match if the class was a negative one (e.g. [^ab]). This has been fixed.
1789     (ii) A negated character class with a single character < 255 is coded as
1790     "not this character" (OP_NOT). This wasn't working properly when the test
1791     character was multibyte, either singly or repeated.
1793     (iii) Repeats of multibyte characters are now handled correctly in UTF-8
1794     mode, for example: \x{100}{2,3}.
1796     (iv) The character escapes \b, \B, \d, \D, \s, \S, \w, and \W (either
1797     singly or repeated) now correctly test multibyte characters. However,
1798     PCRE doesn't recognize any characters with values greater than 255 as
1799     digits, spaces, or word characters. Such characters always match \D, \S,
1800     and \W, and never match \d, \s, or \w.
1802     (v) Classes may now contain characters and character ranges with values
1803     greater than 255. For example: [ab\x{100}-\x{400}].
1805     (vi) pcregrep now has a --utf-8 option (synonym -u) which makes it call
1806     PCRE in UTF-8 mode.
1808     52. The info request value PCRE_INFO_FIRSTCHAR has been renamed
1809     PCRE_INFO_FIRSTBYTE because it is a byte value. However, the old name is
1810     retained for backwards compatibility. (Note that LASTLITERAL is also a byte
1811     value.)
1813     53. The single man page has become too large. I have therefore split it up into
1814     a number of separate man pages. These also give rise to individual HTML pages;
1815     these are now put in a separate directory, and there is an index.html page that
1816     lists them all. Some hyperlinking between the pages has been installed.
1818     54. Added convenience functions for handling named capturing parentheses.
1820     55. Unknown escapes inside character classes (e.g. [\M]) and escapes that
1821     aren't interpreted therein (e.g. [\C]) are literals in Perl. This is now also
1822     true in PCRE, except when the PCRE_EXTENDED option is set, in which case they
1823     are faulted.
1825     56. Introduced HOST_CC and HOST_CFLAGS which can be set in the environment when
1826     calling configure. These values are used when compiling the dftables.c program
1827     which is run to generate the source of the default character tables. They
1828     default to the values of CC and CFLAGS. If you are cross-compiling PCRE,
1829     you will need to set these values.
1831     57. Updated the building process for Windows DLL, as provided by Fred Cox.
1834     Version 3.9 02-Jan-02
1835 nigel 61 ---------------------
1837     1. A bit of extraneous text had somehow crept into the pcregrep documentation.
1839     2. If --disable-static was given, the building process failed when trying to
1840     build pcretest and pcregrep. (For some reason it was using libtool to compile
1841     them, which is not right, as they aren't part of the library.)
1844 nigel 59 Version 3.8 18-Dec-01
1845     ---------------------
1847     1. The experimental UTF-8 code was completely screwed up. It was packing the
1848     bytes in the wrong order. How dumb can you get?
1851 nigel 57 Version 3.7 29-Oct-01
1852     ---------------------
1854     1. In updating pcretest to check change 1 of version 3.6, I screwed up.
1855     This caused pcretest, when used on the test data, to segfault. Unfortunately,
1856     this didn't happen under Solaris 8, where I normally test things.
1858 nigel 59 2. The Makefile had to be changed to make it work on BSD systems, where 'make'
1859     doesn't seem to recognize that ./xxx and xxx are the same file. (This entry
1860     isn't in ChangeLog distributed with 3.7 because I forgot when I hastily made
1861     this fix an hour or so after the initial 3.7 release.)
1862 nigel 57
1863 nigel 59
1864 nigel 55 Version 3.6 23-Oct-01
1865     ---------------------
1867     1. Crashed with /(sens|respons)e and \1ibility/ and "sense and sensibility" if
1868     offsets passed as NULL with zero offset count.
1870     2. The config.guess and config.sub files had not been updated when I moved to
1871     the latest autoconf.
1874 nigel 53 Version 3.5 15-Aug-01
1875     ---------------------
1876 nigel 5
1877 nigel 53 1. Added some missing #if !defined NOPOSIX conditionals in pcretest.c that
1878     had been forgotten.
1880     2. By using declared but undefined structures, we can avoid using "void"
1881     definitions in pcre.h while keeping the internal definitions of the structures
1882     private.
1884     3. The distribution is now built using autoconf 2.50 and libtool 1.4. From a
1885     user point of view, this means that both static and shared libraries are built
1886     by default, but this can be individually controlled. More of the work of
1887     handling this static/shared cases is now inside libtool instead of PCRE's make
1888     file.
1890     4. The pcretest utility is now installed along with pcregrep because it is
1891     useful for users (to test regexs) and by doing this, it automatically gets
1892     relinked by libtool. The documentation has been turned into a man page, so
1893     there are now .1, .txt, and .html versions in /doc.
1895     5. Upgrades to pcregrep:
1896     (i) Added long-form option names like gnu grep.
1897     (ii) Added --help to list all options with an explanatory phrase.
1898     (iii) Added -r, --recursive to recurse into sub-directories.
1899     (iv) Added -f, --file to read patterns from a file.
1901     6. pcre_exec() was referring to its "code" argument before testing that
1902     argument for NULL (and giving an error if it was NULL).
1904     7. Upgraded Makefile.in to allow for compiling in a different directory from
1905     the source directory.
1907     8. Tiny buglet in pcretest: when pcre_fullinfo() was called to retrieve the
1908     options bits, the pointer it was passed was to an int instead of to an unsigned
1909     long int. This mattered only on 64-bit systems.
1911     9. Fixed typo (3.4/1) in pcre.h again. Sigh. I had changed pcre.h (which is
1912     generated) instead of pcre.in, which it its source. Also made the same change
1913     in several of the .c files.
1915     10. A new release of gcc defines printf() as a macro, which broke pcretest
1916     because it had an ifdef in the middle of a string argument for printf(). Fixed
1917     by using separate calls to printf().
1919     11. Added --enable-newline-is-cr and --enable-newline-is-lf to the configure
1920     script, to force use of CR or LF instead of \n in the source. On non-Unix
1921     systems, the value can be set in config.h.
1923     12. The limit of 200 on non-capturing parentheses is a _nesting_ limit, not an
1924     absolute limit. Changed the text of the error message to make this clear, and
1925     likewise updated the man page.
1927     13. The limit of 99 on the number of capturing subpatterns has been removed.
1928     The new limit is 65535, which I hope will not be a "real" limit.
1931 nigel 51 Version 3.4 22-Aug-00
1932     ---------------------
1934     1. Fixed typo in pcre.h: unsigned const char * changed to const unsigned char *.
1936     2. Diagnose condition (?(0) as an error instead of crashing on matching.
1939 nigel 49 Version 3.3 01-Aug-00
1940     ---------------------
1942     1. If an octal character was given, but the value was greater than \377, it
1943     was not getting masked to the least significant bits, as documented. This could
1944     lead to crashes in some systems.
1946     2. Perl 5.6 (if not earlier versions) accepts classes like [a-\d] and treats
1947     the hyphen as a literal. PCRE used to give an error; it now behaves like Perl.
1949     3. Added the functions pcre_free_substring() and pcre_free_substring_list().
1950     These just pass their arguments on to (pcre_free)(), but they are provided
1951     because some uses of PCRE bind it to non-C systems that can call its functions,
1952     but cannot call free() or pcre_free() directly.
1954     4. Add "make test" as a synonym for "make check". Corrected some comments in
1955     the Makefile.
1957     5. Add $(DESTDIR)/ in front of all the paths in the "install" target in the
1958     Makefile.
1960     6. Changed the name of pgrep to pcregrep, because Solaris has introduced a
1961     command called pgrep for grepping around the active processes.
1963     7. Added the beginnings of support for UTF-8 character strings.
1965     8. Arranged for the Makefile to pass over the settings of CC, CFLAGS, and
1966     RANLIB to ./ltconfig so that they are used by libtool. I think these are all
1967     the relevant ones. (AR is not passed because ./ltconfig does its own figuring
1968     out for the ar command.)
1971 nigel 47 Version 3.2 12-May-00
1972     ---------------------
1974     This is purely a bug fixing release.
1976     1. If the pattern /((Z)+|A)*/ was matched agained ZABCDEFG it matched Z instead
1977     of ZA. This was just one example of several cases that could provoke this bug,
1978     which was introduced by change 9 of version 2.00. The code for breaking
1979     infinite loops after an iteration that matches an empty string was't working
1980     correctly.
1982     2. The pcretest program was not imitating Perl correctly for the pattern /a*/g
1983     when matched against abbab (for example). After matching an empty string, it
1984     wasn't forcing anchoring when setting PCRE_NOTEMPTY for the next attempt; this
1985     caused it to match further down the string than it should.
1987     3. The code contained an inclusion of sys/types.h. It isn't clear why this
1988     was there because it doesn't seem to be needed, and it causes trouble on some
1989     systems, as it is not a Standard C header. It has been removed.
1991     4. Made 4 silly changes to the source to avoid stupid compiler warnings that
1992     were reported on the Macintosh. The changes were from
1994     while ((c = *(++ptr)) != 0 && c != '\n');
1995     to
1996     while ((c = *(++ptr)) != 0 && c != '\n') ;
1998     Totally extraordinary, but if that's what it takes...
2000     5. PCRE is being used in one environment where neither memmove() nor bcopy() is
2001     available. Added HAVE_BCOPY and an autoconf test for it; if neither
2002     HAVE_MEMMOVE nor HAVE_BCOPY is set, use a built-in emulation function which
2003     assumes the way PCRE uses memmove() (always moving upwards).
2005     6. PCRE is being used in one environment where strchr() is not available. There
2006     was only one use in pcre.c, and writing it out to avoid strchr() probably gives
2007     faster code anyway.
2010 nigel 45 Version 3.1 09-Feb-00
2011     ---------------------
2013     The only change in this release is the fixing of some bugs in Makefile.in for
2014     the "install" target:
2016     (1) It was failing to install pcreposix.h.
2018     (2) It was overwriting the pcre.3 man page with the pcreposix.3 man page.
2021 nigel 43 Version 3.0 01-Feb-00
2022     ---------------------
2023 nigel 41
2024     1. Add support for the /+ modifier to perltest (to output $` like it does in
2025     pcretest).
2027     2. Add support for the /g modifier to perltest.
2029     3. Fix pcretest so that it behaves even more like Perl for /g when the pattern
2030     matches null strings.
2032     4. Fix perltest so that it doesn't do unwanted things when fed an empty
2033     pattern. Perl treats empty patterns specially - it reuses the most recent
2034     pattern, which is not what we want. Replace // by /(?#)/ in order to avoid this
2035     effect.
2037     5. The POSIX interface was broken in that it was just handing over the POSIX
2038     captured string vector to pcre_exec(), but (since release 2.00) PCRE has
2039     required a bigger vector, with some working space on the end. This means that
2040     the POSIX wrapper now has to get and free some memory, and copy the results.
2042 nigel 43 6. Added some simple autoconf support, placing the test data and the
2043     documentation in separate directories, re-organizing some of the
2044     information files, and making it build pcre-config (a GNU standard). Also added
2045     libtool support for building PCRE as a shared library, which is now the
2046     default.
2047 nigel 41
2048 nigel 43 7. Got rid of the leading zero in the definition of PCRE_MINOR because 08 and
2049     09 are not valid octal constants. Single digits will be used for minor values
2050     less than 10.
2052     8. Defined REG_EXTENDED and REG_NOSUB as zero in the POSIX header, so that
2053     existing programs that set these in the POSIX interface can use PCRE without
2054     modification.
2056     9. Added a new function, pcre_fullinfo() with an extensible interface. It can
2057     return all that pcre_info() returns, plus additional data. The pcre_info()
2058     function is retained for compatibility, but is considered to be obsolete.
2060     10. Added experimental recursion feature (?R) to handle one common case that
2061     Perl 5.6 will be able to do with (?p{...}).
2063     11. Added support for POSIX character classes like [:alpha:], which Perl is
2064     adopting.
2067 nigel 39 Version 2.08 31-Aug-99
2068     ----------------------
2070     1. When startoffset was not zero and the pattern began with ".*", PCRE was not
2071     trying to match at the startoffset position, but instead was moving forward to
2072     the next newline as if a previous match had failed.
2074     2. pcretest was not making use of PCRE_NOTEMPTY when repeating for /g and /G,
2075     and could get into a loop if a null string was matched other than at the start
2076     of the subject.
2078     3. Added definitions of PCRE_MAJOR and PCRE_MINOR to pcre.h so the version can
2079     be distinguished at compile time, and for completeness also added PCRE_DATE.
2081     5. Added Paul Sokolovsky's minor changes to make it easy to compile a Win32 DLL
2082     in GnuWin32 environments.
2085 nigel 37 Version 2.07 29-Jul-99
2086     ----------------------
2088     1. The documentation is now supplied in plain text form and HTML as well as in
2089     the form of man page sources.
2091     2. C++ compilers don't like assigning (void *) values to other pointer types.
2092     In particular this affects malloc(). Although there is no problem in Standard
2093     C, I've put in casts to keep C++ compilers happy.
2095     3. Typo on pcretest.c; a cast of (unsigned char *) in the POSIX regexec() call
2096     should be (const char *).
2098     4. If NOPOSIX is defined, pcretest.c compiles without POSIX support. This may
2099     be useful for non-Unix systems who don't want to bother with the POSIX stuff.
2100     However, I haven't made this a standard facility. The documentation doesn't
2101     mention it, and the Makefile doesn't support it.
2103     5. The Makefile now contains an "install" target, with editable destinations at
2104     the top of the file. The pcretest program is not installed.
2106     6. pgrep -V now gives the PCRE version number and date.
2108     7. Fixed bug: a zero repetition after a literal string (e.g. /abcde{0}/) was
2109     causing the entire string to be ignored, instead of just the last character.
2111     8. If a pattern like /"([^\\"]+|\\.)*"/ is applied in the normal way to a
2112     non-matching string, it can take a very, very long time, even for strings of
2113     quite modest length, because of the nested recursion. PCRE now does better in
2114     some of these cases. It does this by remembering the last required literal
2115     character in the pattern, and pre-searching the subject to ensure it is present
2116     before running the real match. In other words, it applies a heuristic to detect
2117     some types of certain failure quickly, and in the above example, if presented
2118     with a string that has no trailing " it gives "no match" very quickly.
2120     9. A new runtime option PCRE_NOTEMPTY causes null string matches to be ignored;
2121     other alternatives are tried instead.
2124 nigel 35 Version 2.06 09-Jun-99
2125     ----------------------
2127     1. Change pcretest's output for amount of store used to show just the code
2128     space, because the remainder (the data block) varies in size between 32-bit and
2129     64-bit systems.
2131     2. Added an extra argument to pcre_exec() to supply an offset in the subject to
2132     start matching at. This allows lookbehinds to work when searching for multiple
2133     occurrences in a string.
2135     3. Added additional options to pcretest for testing multiple occurrences:
2137     /+ outputs the rest of the string that follows a match
2138     /g loops for multiple occurrences, using the new startoffset argument
2139     /G loops for multiple occurrences by passing an incremented pointer
2141     4. PCRE wasn't doing the "first character" optimization for patterns starting
2142     with \b or \B, though it was doing it for other lookbehind assertions. That is,
2143     it wasn't noticing that a match for a pattern such as /\bxyz/ has to start with
2144     the letter 'x'. On long subject strings, this gives a significant speed-up.
2147 nigel 33 Version 2.05 21-Apr-99
2148     ----------------------
2150     1. Changed the type of magic_number from int to long int so that it works
2151     properly on 16-bit systems.
2153     2. Fixed a bug which caused patterns starting with .* not to work correctly
2154     when the subject string contained newline characters. PCRE was assuming
2155     anchoring for such patterns in all cases, which is not correct because .* will
2156     not pass a newline unless PCRE_DOTALL is set. It now assumes anchoring only if
2157     DOTALL is set at top level; otherwise it knows that patterns starting with .*
2158     must be retried after every newline in the subject.
2161 nigel 31 Version 2.04 18-Feb-99
2162     ----------------------
2164     1. For parenthesized subpatterns with repeats whose minimum was zero, the
2165     computation of the store needed to hold the pattern was incorrect (too large).
2166     If such patterns were nested a few deep, this could multiply and become a real
2167     problem.
2169     2. Added /M option to pcretest to show the memory requirement of a specific
2170     pattern. Made -m a synonym of -s (which does this globally) for compatibility.
2172     3. Subpatterns of the form (regex){n,m} (i.e. limited maximum) were being
2173     compiled in such a way that the backtracking after subsequent failure was
2174     pessimal. Something like (a){0,3} was compiled as (a)?(a)?(a)? instead of
2175     ((a)((a)(a)?)?)? with disastrous performance if the maximum was of any size.
2178 nigel 29 Version 2.03 02-Feb-99
2179     ----------------------
2181     1. Fixed typo and small mistake in man page.
2183 nigel 31 2. Added 4th condition (GPL supersedes if conflict) and created separate
2184     LICENCE file containing the conditions.
2185 nigel 29
2186     3. Updated pcretest so that patterns such as /abc\/def/ work like they do in
2187     Perl, that is the internal \ allows the delimiter to be included in the
2188     pattern. Locked out the use of \ as a delimiter. If \ immediately follows
2189     the final delimiter, add \ to the end of the pattern (to test the error).
2191     4. Added the convenience functions for extracting substrings after a successful
2192     match. Updated pcretest to make it able to test these functions.
2195 nigel 27 Version 2.02 14-Jan-99
2196     ----------------------
2198     1. Initialized the working variables associated with each extraction so that
2199     their saving and restoring doesn't refer to uninitialized store.
2201     2. Put dummy code into study.c in order to trick the optimizer of the IBM C
2202     compiler for OS/2 into generating correct code. Apparently IBM isn't going to
2203     fix the problem.
2205     3. Pcretest: the timing code wasn't using LOOPREPEAT for timing execution
2206     calls, and wasn't printing the correct value for compiling calls. Increased the
2207     default value of LOOPREPEAT, and the number of significant figures in the
2208     times.
2210     4. Changed "/bin/rm" in the Makefile to "-rm" so it works on Windows NT.
2212     5. Renamed "deftables" as "dftables" to get it down to 8 characters, to avoid
2213     a building problem on Windows NT with a FAT file system.
2216 nigel 25 Version 2.01 21-Oct-98
2217     ----------------------
2219     1. Changed the API for pcre_compile() to allow for the provision of a pointer
2220     to character tables built by pcre_maketables() in the current locale. If NULL
2221     is passed, the default tables are used.
2224 nigel 23 Version 2.00 24-Sep-98
2225 nigel 21 ----------------------
2227 nigel 23 1. Since the (>?) facility is in Perl 5.005, don't require PCRE_EXTRA to enable
2228     it any more.
2230     2. Allow quantification of (?>) groups, and make it work correctly.
2232     3. The first character computation wasn't working for (?>) groups.
2234     4. Correct the implementation of \Z (it is permitted to match on the \n at the
2235     end of the subject) and add 5.005's \z, which really does match only at the
2236     very end of the subject.
2238     5. Remove the \X "cut" facility; Perl doesn't have it, and (?> is neater.
2240     6. Remove the ability to specify CASELESS, MULTILINE, DOTALL, and
2241     DOLLAR_END_ONLY at runtime, to make it possible to implement the Perl 5.005
2242     localized options. All options to pcre_study() were also removed.
2244     7. Add other new features from 5.005:
2246     $(?<= positive lookbehind
2247     $(?<! negative lookbehind
2248     (?imsx-imsx) added the unsetting capability
2249     such a setting is global if at outer level; local otherwise
2250     (?imsx-imsx:) non-capturing groups with option setting
2251     (?(cond)re|re) conditional pattern matching
2253     A backreference to itself in a repeated group matches the previous
2254     captured string.
2256     8. General tidying up of studying (both automatic and via "study")
2257     consequential on the addition of new assertions.
2259     9. As in 5.005, unlimited repeated groups that could match an empty substring
2260     are no longer faulted at compile time. Instead, the loop is forcibly broken at
2261     runtime if any iteration does actually match an empty substring.
2263     10. Include the RunTest script in the distribution.
2265     11. Added tests from the Perl 5.005_02 distribution. This showed up a few
2266     discrepancies, some of which were old and were also with respect to 5.004. They
2267     have now been fixed.
2270     Version 1.09 28-Apr-98
2271     ----------------------
2273 nigel 21 1. A negated single character class followed by a quantifier with a minimum
2274     value of one (e.g. [^x]{1,6} ) was not compiled correctly. This could lead to
2275     program crashes, or just wrong answers. This did not apply to negated classes
2276     containing more than one character, or to minima other than one.
2279 nigel 19 Version 1.08 27-Mar-98
2280     ----------------------
2282     1. Add PCRE_UNGREEDY to invert the greediness of quantifiers.
2284     2. Add (?U) and (?X) to set PCRE_UNGREEDY and PCRE_EXTRA respectively. The
2285     latter must appear before anything that relies on it in the pattern.
2288 nigel 17 Version 1.07 16-Feb-98
2289     ----------------------
2291     1. A pattern such as /((a)*)*/ was not being diagnosed as in error (unlimited
2292     repeat of a potentially empty string).
2295 nigel 15 Version 1.06 23-Jan-98
2296     ----------------------
2298     1. Added Markus Oberhumer's little patches for C++.
2300     2. Literal strings longer than 255 characters were broken.
2303 nigel 13 Version 1.05 23-Dec-97
2304     ----------------------
2306     1. Negated character classes containing more than one character were failing if
2307     PCRE_CASELESS was set at run time.
2310 nigel 11 Version 1.04 19-Dec-97
2311     ----------------------
2313     1. Corrected the man page, where some "const" qualifiers had been omitted.
2315     2. Made debugging output print "{0,xxx}" instead of just "{,xxx}" to agree with
2316     input syntax.
2318     3. Fixed memory leak which occurred when a regex with back references was
2319     matched with an offsets vector that wasn't big enough. The temporary memory
2320     that is used in this case wasn't being freed if the match failed.
2322     4. Tidied pcretest to ensure it frees memory that it gets.
2324     5. Temporary memory was being obtained in the case where the passed offsets
2325     vector was exactly big enough.
2327     6. Corrected definition of offsetof() from change 5 below.
2329     7. I had screwed up change 6 below and broken the rules for the use of
2330     setjmp(). Now fixed.
2333 nigel 9 Version 1.03 18-Dec-97
2334     ----------------------
2336     1. A erroneous regex with a missing opening parenthesis was correctly
2337     diagnosed, but PCRE attempted to access brastack[-1], which could cause crashes
2338     on some systems.
2340     2. Replaced offsetof(real_pcre, code) by offsetof(real_pcre, code[0]) because
2341     it was reported that one broken compiler failed on the former because "code" is
2342     also an independent variable.
2344     3. The erroneous regex a[]b caused an array overrun reference.
2346     4. A regex ending with a one-character negative class (e.g. /[^k]$/) did not
2347     fail on data ending with that character. (It was going on too far, and checking
2348     the next character, typically a binary zero.) This was specific to the
2349     optimized code for single-character negative classes.
2351     5. Added a contributed patch from the TIN world which does the following:
2353     + Add an undef for memmove, in case the the system defines a macro for it.
2355     + Add a definition of offsetof(), in case there isn't one. (I don't know
2356     the reason behind this - offsetof() is part of the ANSI standard - but
2357     it does no harm).
2359     + Reduce the ifdef's in pcre.c using macro DPRINTF, thereby eliminating
2360     most of the places where whitespace preceded '#'. I have given up and
2361     allowed the remaining 2 cases to be at the margin.
2363     + Rename some variables in pcre to eliminate shadowing. This seems very
2364     pedantic, but does no harm, of course.
2366     6. Moved the call to setjmp() into its own function, to get rid of warnings
2367     from gcc -Wall, and avoided calling it at all unless PCRE_EXTRA is used.
2369     7. Constructs such as \d{8,} were compiling into the equivalent of
2370 nigel 11 \d{8}\d{0,65527} instead of \d{8}\d* which didn't make much difference to the
2371 nigel 9 outcome, but in this particular case used more store than had been allocated,
2372     which caused the bug to be discovered because it threw up an internal error.
2374     8. The debugging code in both pcre and pcretest for outputting the compiled
2375     form of a regex was going wrong in the case of back references followed by
2376     curly-bracketed repeats.
2379 nigel 7 Version 1.02 12-Dec-97
2380     ----------------------
2382     1. Typos in pcre.3 and comments in the source fixed.
2384     2. Applied a contributed patch to get rid of places where it used to remove
2385     'const' from variables, and fixed some signed/unsigned and uninitialized
2386     variable warnings.
2388     3. Added the "runtest" target to Makefile.
2390     4. Set default compiler flag to -O2 rather than just -O.
2393 nigel 5 Version 1.01 19-Nov-97
2394     ----------------------
2396     1. PCRE was failing to diagnose unlimited repeat of empty string for patterns
2397     like /([ab]*)*/, that is, for classes with more than one character in them.
2399     2. Likewise, it wasn't diagnosing patterns with "once-only" subpatterns, such
2400     as /((?>a*))*/ (a PCRE_EXTRA facility).
2403     Version 1.00 18-Nov-97
2404     ----------------------
2406     1. Added compile-time macros to support systems such as SunOS4 which don't have
2407     memmove() or strerror() but have other things that can be used instead.
2409     2. Arranged that "make clean" removes the executables.
2412 nigel 3 Version 0.99 27-Oct-97
2413     ----------------------
2415     1. Fixed bug in code for optimizing classes with only one character. It was
2416     initializing a 32-byte map regardless, which could cause it to run off the end
2417     of the memory it had got.
2419     2. Added, conditional on PCRE_EXTRA, the proposed (?>REGEX) construction.
2422     Version 0.98 22-Oct-97
2423     ----------------------
2425     1. Fixed bug in code for handling temporary memory usage when there are more
2426     back references than supplied space in the ovector. This could cause segfaults.
2429     Version 0.97 21-Oct-97
2430     ----------------------
2432     1. Added the \X "cut" facility, conditional on PCRE_EXTRA.
2434     2. Optimized negated single characters not to use a bit map.
2436     3. Brought error texts together as macro definitions; clarified some of them;
2437     fixed one that was wrong - it said "range out of order" when it meant "invalid
2438     escape sequence".
2440     4. Changed some char * arguments to const char *.
2442     5. Added PCRE_NOTBOL and PCRE_NOTEOL (from POSIX).
2444     6. Added the POSIX-style API wrapper in pcreposix.a and testing facilities in
2445     pcretest.
2448     Version 0.96 16-Oct-97
2449     ----------------------
2451     1. Added a simple "pgrep" utility to the distribution.
2453     2. Fixed an incompatibility with Perl: "{" is now treated as a normal character
2454     unless it appears in one of the precise forms "{ddd}", "{ddd,}", or "{ddd,ddd}"
2455     where "ddd" means "one or more decimal digits".
2457     3. Fixed serious bug. If a pattern had a back reference, but the call to
2458     pcre_exec() didn't supply a large enough ovector to record the related
2459     identifying subpattern, the match always failed. PCRE now remembers the number
2460     of the largest back reference, and gets some temporary memory in which to save
2461     the offsets during matching if necessary, in order to ensure that
2462     backreferences always work.
2464     4. Increased the compatibility with Perl in a number of ways:
2466     (a) . no longer matches \n by default; an option PCRE_DOTALL is provided
2467     to request this handling. The option can be set at compile or exec time.
2469     (b) $ matches before a terminating newline by default; an option
2470     PCRE_DOLLAR_ENDONLY is provided to override this (but not in multiline
2471     mode). The option can be set at compile or exec time.
2473     (c) The handling of \ followed by a digit other than 0 is now supposed to be
2474     the same as Perl's. If the decimal number it represents is less than 10
2475     or there aren't that many previous left capturing parentheses, an octal
2476     escape is read. Inside a character class, it's always an octal escape,
2477     even if it is a single digit.
2479     (d) An escaped but undefined alphabetic character is taken as a literal,
2480     unless PCRE_EXTRA is set. Currently this just reserves the remaining
2481     escapes.
2483     (e) {0} is now permitted. (The previous item is removed from the compiled
2484     pattern).
2486     5. Changed all the names of code files so that the basic parts are no longer
2487     than 10 characters, and abolished the teeny "globals.c" file.
2489     6. Changed the handling of character classes; they are now done with a 32-byte
2490     bit map always.
2492     7. Added the -d and /D options to pcretest to make it possible to look at the
2493     internals of compilation without having to recompile pcre.
2496     Version 0.95 23-Sep-97
2497     ----------------------
2499     1. Fixed bug in pre-pass concerning escaped "normal" characters such as \x5c or
2500     \x20 at the start of a run of normal characters. These were being treated as
2501     real characters, instead of the source characters being re-checked.
2504     Version 0.94 18-Sep-97
2505     ----------------------
2507     1. The functions are now thread-safe, with the caveat that the global variables
2508     containing pointers to malloc() and free() or alternative functions are the
2509     same for all threads.
2511     2. Get pcre_study() to generate a bitmap of initial characters for non-
2512     anchored patterns when this is possible, and use it if passed to pcre_exec().
2515     Version 0.93 15-Sep-97
2516     ----------------------
2518     1. /(b)|(:+)/ was computing an incorrect first character.
2520     2. Add pcre_study() to the API and the passing of pcre_extra to pcre_exec(),
2521     but not actually doing anything yet.
2523     3. Treat "-" characters in classes that cannot be part of ranges as literals,
2524     as Perl does (e.g. [-az] or [az-]).
2526     4. Set the anchored flag if a branch starts with .* or .*? because that tests
2527     all possible positions.
2529     5. Split up into different modules to avoid including unneeded functions in a
2530     compiled binary. However, compile and exec are still in one module. The "study"
2531     function is split off.
2533     6. The character tables are now in a separate module whose source is generated
2534     by an auxiliary program - but can then be edited by hand if required. There are
2535     now no calls to isalnum(), isspace(), isdigit(), isxdigit(), tolower() or
2536     toupper() in the code.
2538     7. Turn the malloc/free funtions variables into pcre_malloc and pcre_free and
2539     make them global. Abolish the function for setting them, as the caller can now
2540     set them directly.
2543     Version 0.92 11-Sep-97
2544     ----------------------
2546     1. A repeat with a fixed maximum and a minimum of 1 for an ordinary character
2547     (e.g. /a{1,3}/) was broken (I mis-optimized it).
2549     2. Caseless matching was not working in character classes if the characters in
2550     the pattern were in upper case.
2552     3. Make ranges like [W-c] work in the same way as Perl for caseless matching.
2554     4. Make PCRE_ANCHORED public and accept as a compile option.
2556     5. Add an options word to pcre_exec() and accept PCRE_ANCHORED and
2557     PCRE_CASELESS at run time. Add escapes \A and \I to pcretest to cause it to
2558     pass them.
2560     6. Give an error if bad option bits passed at compile or run time.
2562     7. Add PCRE_MULTILINE at compile and exec time, and (?m) as well. Add \M to
2563     pcretest to cause it to pass that flag.
2565     8. Add pcre_info(), to get the number of identifying subpatterns, the stored
2566     options, and the first character, if set.
2568     9. Recognize C+ or C{n,m} where n >= 1 as providing a fixed starting character.
2571     Version 0.91 10-Sep-97
2572     ----------------------
2574     1. PCRE was failing to diagnose unlimited repeats of subpatterns that could
2575     match the empty string as in /(a*)*/. It was looping and ultimately crashing.
2577     2. PCRE was looping on encountering an indefinitely repeated back reference to
2578     a subpattern that had matched an empty string, e.g. /(a|)\1*/. It now does what
2579     Perl does - treats the match as successful.
2581     ****


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