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Revision 98 - (hide annotations) (download)
Mon Mar 5 15:55:02 2007 UTC (8 years, 1 month ago) by ph10
File size: 119130 byte(s)
This is a second preliminary update, after having done a test build and also a 
check of the maintenance programs. The version is now 7.1-RC1. In autogen.sh, 
autoheader is now before automake, and Tech.Notes (being now in the "maintain" 
directory) are no longer distributed.

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     that is more "standard", making use of automake and other autotools.
11 nigel 93 Version 7.0 19-Dec-06
12     ---------------------
14     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
15     moving to gcc 4.1.1.
17     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
18     sys/time.h, which is documented as needed for this function. It doesn't
19     seem to matter on Linux, but it showed up on some releases of OS X.
21     3. It seems that there are systems where bytes whose values are greater than
22     127 match isprint() in the "C" locale. The "C" locale should be the
23     default when a C program starts up. In most systems, only ASCII printing
24     characters match isprint(). This difference caused the output from pcretest
25     to vary, making some of the tests fail. I have changed pcretest so that:
27     (a) When it is outputting text in the compiled version of a pattern, bytes
28     other than 32-126 are always shown as hex escapes.
30     (b) When it is outputting text that is a matched part of a subject string,
31     it does the same, unless a different locale has been set for the match
32     (using the /L modifier). In this case, it uses isprint() to decide.
34     4. Fixed a major bug that caused incorrect computation of the amount of memory
35     required for a compiled pattern when options that changed within the
36     pattern affected the logic of the preliminary scan that determines the
37     length. The relevant options are -x, and -i in UTF-8 mode. The result was
38     that the computed length was too small. The symptoms of this bug were
39     either the PCRE error "internal error: code overflow" from pcre_compile(),
40     or a glibc crash with a message such as "pcretest: free(): invalid next
41     size (fast)". Examples of patterns that provoked this bug (shown in
42     pcretest format) are:
44     /(?-x: )/x
45     /(?x)(?-x: \s*#\s*)/
46     /((?i)[\x{c0}])/8
47     /(?i:[\x{c0}])/8
49     HOWEVER: Change 17 below makes this fix obsolete as the memory computation
50     is now done differently.
52     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
53     wrapper classes; (b) implement a new function in the C++ scanner that is
54     more efficient than the old way of doing things because it avoids levels of
55     recursion in the regex matching; (c) add a paragraph to the documentation
56     for the FullMatch() function.
58     6. The escape sequence \n was being treated as whatever was defined as
59     "newline". Not only was this contrary to the documentation, which states
60     that \n is character 10 (hex 0A), but it also went horribly wrong when
61     "newline" was defined as CRLF. This has been fixed.
63     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
64     was being set to -1 for the "end of line" case (supposedly a value that no
65     character can have). Though this value is never used (the check for end of
66     line is "zero bytes in current character"), it caused compiler complaints.
67     I've changed it to 0xffffffff.
69     8. In pcre_version.c, the version string was being built by a sequence of
70     C macros that, in the event of PCRE_PRERELEASE being defined as an empty
71     string (as it is for production releases) called a macro with an empty
72     argument. The C standard says the result of this is undefined. The gcc
73     compiler treats it as an empty string (which was what was wanted) but it is
74     reported that Visual C gives an error. The source has been hacked around to
75     avoid this problem.
77     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
78     builds of pcretest, and changed the call to _setmode() to use _O_BINARY
79     instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
80     of them did).
82     10. Originally, pcretest opened its input and output without "b"; then I was
83     told that "b" was needed in some environments, so it was added for release
84     5.0 to both the input and output. (It makes no difference on Unix-like
85     systems.) Later I was told that it is wrong for the input on Windows. I've
86     now abstracted the modes into two macros, to make it easier to fiddle with
87     them, and removed "b" from the input mode under Windows.
89     11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
91     12. Added -help and --help to pcretest as an official way of being reminded
92     of the options.
94     13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
95     and pcrecpp.cc because they annoy compilers at high warning levels.
97     14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
99     15. Fixed an occurrence of == in configure.ac that should have been = (shell
100     scripts are not C programs :-) and which was not noticed because it works
101     on Linux.
103     16. pcretest is supposed to handle any length of pattern and data line (as one
104     line or as a continued sequence of lines) by extending its input buffer if
105     necessary. This feature was broken for very long pattern lines, leading to
106     a string of junk being passed to pcre_compile() if the pattern was longer
107     than about 50K.
109     17. I have done a major re-factoring of the way pcre_compile() computes the
110     amount of memory needed for a compiled pattern. Previously, there was code
111     that made a preliminary scan of the pattern in order to do this. That was
112     OK when PCRE was new, but as the facilities have expanded, it has become
113     harder and harder to keep it in step with the real compile phase, and there
114     have been a number of bugs (see for example, 4 above). I have now found a
115     cunning way of running the real compile function in a "fake" mode that
116     enables it to compute how much memory it would need, while actually only
117     ever using a few hundred bytes of working memory and without too many
118     tests of the mode. This should make future maintenance and development
119     easier. A side effect of this work is that the limit of 200 on the nesting
120     depth of parentheses has been removed (though this was never a serious
121     limitation, I suspect). However, there is a downside: pcre_compile() now
122     runs more slowly than before (30% or more, depending on the pattern). I
123     hope this isn't a big issue. There is no effect on runtime performance.
125     18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
126     newline (only possible for the last line of a file) and it was a
127     pattern that set a locale (followed by /Lsomething), pcretest crashed.
129     19. Added additional timing features to pcretest. (1) The -tm option now times
130     matching only, not compiling. (2) Both -t and -tm can be followed, as a
131     separate command line item, by a number that specifies the number of
132     repeats to use when timing. The default is 50000; this gives better
133     precision, but takes uncomfortably long for very large patterns.
135     20. Extended pcre_study() to be more clever in cases where a branch of a
136     subpattern has no definite first character. For example, (a*|b*)[cd] would
137     previously give no result from pcre_study(). Now it recognizes that the
138     first character must be a, b, c, or d.
140     21. There was an incorrect error "recursive call could loop indefinitely" if
141     a subpattern (or the entire pattern) that was being tested for matching an
142     empty string contained only one non-empty item after a nested subpattern.
143     For example, the pattern (?>\x{100}*)\d(?R) provoked this error
144     incorrectly, because the \d was being skipped in the check.
146     22. The pcretest program now has a new pattern option /B and a command line
147     option -b, which is equivalent to adding /B to every pattern. This causes
148     it to show the compiled bytecode, without the additional information that
149     -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
150     is the same as /B/I).
152     23. A new optimization is now able automatically to treat some sequences such
153     as a*b as a*+b. More specifically, if something simple (such as a character
154     or a simple class like \d) has an unlimited quantifier, and is followed by
155     something that cannot possibly match the quantified thing, the quantifier
156     is automatically "possessified".
158     24. A recursive reference to a subpattern whose number was greater than 39
159     went wrong under certain circumstances in UTF-8 mode. This bug could also
160     have affected the operation of pcre_study().
162     25. Realized that a little bit of performance could be had by replacing
163     (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
165     26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
167     27. Possessive quantifiers such as a++ were previously implemented by turning
168     them into atomic groups such as ($>a+). Now they have their own opcodes,
169     which improves performance. This includes the automatically created ones
170     from 23 above.
172     28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
173     lookahead was broken if it was not anchored. PCRE was mistakenly expecting
174     the first matched character to be a colon. This applied both to named and
175     numbered groups.
177     29. The ucpinternal.h header file was missing its idempotency #ifdef.
179     30. I was sent a "project" file called libpcre.a.dev which I understand makes
180     building PCRE on Windows easier, so I have included it in the distribution.
182     31. There is now a check in pcretest against a ridiculously large number being
183     returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
184     loop, the loop is abandoned.
186     32. Forward references to subpatterns in conditions such as (?(2)...) where
187     subpattern 2 is defined later cause pcre_compile() to search forwards in
188     the pattern for the relevant set of parentheses. This search went wrong
189     when there were unescaped parentheses in a character class, parentheses
190     escaped with \Q...\E, or parentheses in a #-comment in /x mode.
192     33. "Subroutine" calls and backreferences were previously restricted to
193     referencing subpatterns earlier in the regex. This restriction has now
194     been removed.
196     34. Added a number of extra features that are going to be in Perl 5.10. On the
197     whole, these are just syntactic alternatives for features that PCRE had
198     previously implemented using the Python syntax or my own invention. The
199     other formats are all retained for compatibility.
201     (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
202     as (?P<name>...). The new forms, as well as being in Perl 5.10, are
203     also .NET compatible.
205     (b) A recursion or subroutine call to a named group can now be defined as
206     (?&name) as well as (?P>name).
208     (c) A backreference to a named group can now be defined as \k<name> or
209     \k'name' as well as (?P=name). The new forms, as well as being in Perl
210     5.10, are also .NET compatible.
212     (d) A conditional reference to a named group can now use the syntax
213     (?(<name>) or (?('name') as well as (?(name).
215     (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
216     groups (named and numbered) that are never evaluated inline, but can be
217     called as "subroutines" from elsewhere. In effect, the DEFINE condition
218     is always false. There may be only one alternative in such a group.
220     (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
221     as the simple (?(R). The condition is true only if the most recent
222     recursion is that of the given number or name. It does not search out
223     through the entire recursion stack.
225     (g) The escape \gN or \g{N} has been added, where N is a positive or
226     negative number, specifying an absolute or relative reference.
228     35. Tidied to get rid of some further signed/unsigned compiler warnings and
229     some "unreachable code" warnings.
231     36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
232     things, this adds five new scripts.
234     37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
235     There were also incompatibilities regarding the handling of \Q..\E inside
236     character classes, for example with patterns like [\Qa\E-\Qz\E] where the
237     hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
239     38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
240     matches an empty string, and forcibly breaks the loop. There were bugs in
241     this code in non-simple cases. For a pattern such as ^(a()*)* matched
242     against aaaa the result was just "a" rather than "aaaa", for example. Two
243     separate and independent bugs (that affected different cases) have been
244     fixed.
246     39. Refactored the code to abolish the use of different opcodes for small
247     capturing bracket numbers. This is a tidy that I avoided doing when I
248     removed the limit on the number of capturing brackets for 3.5 back in 2001.
249     The new approach is not only tidier, it makes it possible to reduce the
250     memory needed to fix the previous bug (38).
252     40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
253     sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
254     processing dot, circumflex, or dollar metacharacters, or #-comments in /x
255     mode.
257     41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
258     report.
260     42. Applied patch, originally from Ari Pollak, modified by Google, to allow
261     copy construction and assignment in the C++ wrapper.
263     43. Updated pcregrep to support "--newline=any". In the process, I fixed a
264     couple of bugs that could have given wrong results in the "--newline=crlf"
265     case.
267     44. Added a number of casts and did some reorganization of signed/unsigned int
268     variables following suggestions from Dair Grant. Also renamed the variable
269     "this" as "item" because it is a C++ keyword.
271     45. Arranged for dftables to add
273     #include "pcre_internal.h"
275     to pcre_chartables.c because without it, gcc 4.x may remove the array
276     definition from the final binary if PCRE is built into a static library and
277     dead code stripping is activated.
279     46. For an unanchored pattern, if a match attempt fails at the start of a
280     newline sequence, and the newline setting is CRLF or ANY, and the next two
281     characters are CRLF, advance by two characters instead of one.
284 nigel 91 Version 6.7 04-Jul-06
285     ---------------------
287     1. In order to handle tests when input lines are enormously long, pcretest has
288     been re-factored so that it automatically extends its buffers when
289     necessary. The code is crude, but this _is_ just a test program. The
290     default size has been increased from 32K to 50K.
292     2. The code in pcre_study() was using the value of the re argument before
293     testing it for NULL. (Of course, in any sensible call of the function, it
294     won't be NULL.)
296     3. The memmove() emulation function in pcre_internal.h, which is used on
297     systems that lack both memmove() and bcopy() - that is, hardly ever -
298     was missing a "static" storage class specifier.
300     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
301     containing an extended class (one that cannot be represented by a bitmap
302     because it contains high-valued characters or Unicode property items, e.g.
303     [\pZ]). Almost always one would set UTF-8 mode when processing such a
304     pattern, but PCRE should not loop if you do not (it no longer does).
305     [Detail: two cases were found: (a) a repeated subpattern containing an
306     extended class; (b) a recursive reference to a subpattern that followed a
307     previous extended class. It wasn't skipping over the extended class
308     correctly when UTF-8 mode was not set.]
310     5. A negated single-character class was not being recognized as fixed-length
311     in lookbehind assertions such as (?<=[^f]), leading to an incorrect
312     compile error "lookbehind assertion is not fixed length".
314     6. The RunPerlTest auxiliary script was showing an unexpected difference
315     between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
316     write a Perl script that can interpret lines of an input file either as
317     byte characters or as UTF-8, which is what "perltest" was being required to
318     do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
319     can't do is switch easily at run time between having the "use utf8;" pragma
320     or not. In the end, I fudged it by using the RunPerlTest script to insert
321     "use utf8;" explicitly for the UTF-8 tests.
323     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
324     the end of the subject string, contrary to the documentation and to what
325     Perl does. This was true of both matching functions. Now it matches only at
326     the start of the subject and immediately after *internal* newlines.
328     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
329     a pointer to an int instead of a pointer to an unsigned long int. This
330     caused problems on 64-bit systems.
332     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
333     instance of the 'standard' template library not being so standard".
335     10. There was no check on the number of named subpatterns nor the maximum
336     length of a subpattern name. The product of these values is used to compute
337     the size of the memory block for a compiled pattern. By supplying a very
338     long subpattern name and a large number of named subpatterns, the size
339     computation could be caused to overflow. This is now prevented by limiting
340     the length of names to 32 characters, and the number of named subpatterns
341     to 10,000.
343     11. Subpatterns that are repeated with specific counts have to be replicated in
344     the compiled pattern. The size of memory for this was computed from the
345     length of the subpattern and the repeat count. The latter is limited to
346     65535, but there was no limit on the former, meaning that integer overflow
347     could in principle occur. The compiled length of a repeated subpattern is
348     now limited to 30,000 bytes in order to prevent this.
350     12. Added the optional facility to have named substrings with the same name.
352     13. Added the ability to use a named substring as a condition, using the
353     Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
354     are numbers (not recommended). Forward references are permitted.
356     14. Added forward references in named backreferences (if you see what I mean).
358     15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
359     pattern could run off the end of the subject. For example, the pattern
360     "(?s)(.{1,5})"8 did this with the subject "ab".
362     16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
363     PCRE_CASELESS was set when matching characters that were quantified with ?
364     or *.
366     17. A character class other than a single negated character that had a minimum
367     but no maximum quantifier - for example [ab]{6,} - was not handled
368     correctly by pce_dfa_exec(). It would match only one character.
370     18. A valid (though odd) pattern that looked like a POSIX character
371     class but used an invalid character after [ (for example [[,abc,]]) caused
372     pcre_compile() to give the error "Failed: internal error: code overflow" or
373     in some cases to crash with a glibc free() error. This could even happen if
374     the pattern terminated after [[ but there just happened to be a sequence of
375     letters, a binary zero, and a closing ] in the memory that followed.
377     19. Perl's treatment of octal escapes in the range \400 to \777 has changed
378     over the years. Originally (before any Unicode support), just the bottom 8
379     bits were taken. Thus, for example, \500 really meant \100. Nowadays the
380     output from "man perlunicode" includes this:
382     The regular expression compiler produces polymorphic opcodes. That
383     is, the pattern adapts to the data and automatically switches to
384     the Unicode character scheme when presented with Unicode data--or
385     instead uses a traditional byte scheme when presented with byte
386     data.
388     Sadly, a wide octal escape does not cause a switch, and in a string with
389     no other multibyte characters, these octal escapes are treated as before.
390     Thus, in Perl, the pattern /\500/ actually matches \100 but the pattern
391     /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
392     Unicode string.
394     I have not perpetrated such confusion in PCRE. Up till now, it took just
395     the bottom 8 bits, as in old Perl. I have now made octal escapes with
396     values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
397     translate to the appropriate multibyte character.
399     29. Applied some refactoring to reduce the number of warnings from Microsoft
400     and Borland compilers. This has included removing the fudge introduced
401     seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
402     a warning about an unused variable.
404     21. PCRE has not included VT (character 0x0b) in the set of whitespace
405     characters since release 4.0, because Perl (from release 5.004) does not.
406     [Or at least, is documented not to: some releases seem to be in conflict
407     with the documentation.] However, when a pattern was studied with
408     pcre_study() and all its branches started with \s, PCRE still included VT
409     as a possible starting character. Of course, this did no harm; it just
410     caused an unnecessary match attempt.
412     22. Removed a now-redundant internal flag bit that recorded the fact that case
413     dependency changed within the pattern. This was once needed for "required
414     byte" processing, but is no longer used. This recovers a now-scarce options
415     bit. Also moved the least significant internal flag bit to the most-
416     significant bit of the word, which was not previously used (hangover from
417     the days when it was an int rather than a uint) to free up another bit for
418     the future.
420     23. Added support for CRLF line endings as well as CR and LF. As well as the
421     default being selectable at build time, it can now be changed at runtime
422     via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
423     specify that it is scanning data with non-default line endings.
425     24. Changed the definition of CXXLINK to make it agree with the definition of
426     LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
428     25. Applied Ian Taylor's patches to avoid using another stack frame for tail
429     recursions. This makes a big different to stack usage for some patterns.
431     26. If a subpattern containing a named recursion or subroutine reference such
432     as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
433     the space required for the compiled pattern went wrong and gave too small a
434     value. Depending on the environment, this could lead to "Failed: internal
435     error: code overflow at offset 49" or "glibc detected double free or
436     corruption" errors.
438     27. Applied patches from Google (a) to support the new newline modes and (b) to
439     advance over multibyte UTF-8 characters in GlobalReplace.
441     28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
442     difference for some implementation of PCRE in some Windows version.
444     29. Added some extra testing facilities to pcretest:
446     \q<number> in a data line sets the "match limit" value
447     \Q<number> in a data line sets the "match recursion limt" value
448     -S <number> sets the stack size, where <number> is in megabytes
450     The -S option isn't available for Windows.
453 nigel 89 Version 6.6 06-Feb-06
454     ---------------------
456     1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
457     in pcreposix.h. I have copied the definition from pcre.h.
459     2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
460     because pcre.h is no longer a built file.
462     3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
463     not normally included in the compiled code.
466 nigel 87 Version 6.5 01-Feb-06
467     ---------------------
469     1. When using the partial match feature with pcre_dfa_exec(), it was not
470     anchoring the second and subsequent partial matches at the new starting
471     point. This could lead to incorrect results. For example, with the pattern
472     /1234/, partially matching against "123" and then "a4" gave a match.
474     2. Changes to pcregrep:
476     (a) All non-match returns from pcre_exec() were being treated as failures
477     to match the line. Now, unless the error is PCRE_ERROR_NOMATCH, an
478     error message is output. Some extra information is given for the
480     probably the only errors that are likely to be caused by users (by
481     specifying a regex that has nested indefinite repeats, for instance).
482     If there are more than 20 of these errors, pcregrep is abandoned.
484     (b) A binary zero was treated as data while matching, but terminated the
485     output line if it was written out. This has been fixed: binary zeroes
486     are now no different to any other data bytes.
488     (c) Whichever of the LC_ALL or LC_CTYPE environment variables is set is
489     used to set a locale for matching. The --locale=xxxx long option has
490     been added (no short equivalent) to specify a locale explicitly on the
491     pcregrep command, overriding the environment variables.
493     (d) When -B was used with -n, some line numbers in the output were one less
494     than they should have been.
496     (e) Added the -o (--only-matching) option.
498     (f) If -A or -C was used with -c (count only), some lines of context were
499     accidentally printed for the final match.
501     (g) Added the -H (--with-filename) option.
503     (h) The combination of options -rh failed to suppress file names for files
504     that were found from directory arguments.
506     (i) Added the -D (--devices) and -d (--directories) options.
508     (j) Added the -F (--fixed-strings) option.
510     (k) Allow "-" to be used as a file name for -f as well as for a data file.
512     (l) Added the --colo(u)r option.
514     (m) Added Jeffrey Friedl's -S testing option, but within #ifdefs so that it
515     is not present by default.
517     3. A nasty bug was discovered in the handling of recursive patterns, that is,
518     items such as (?R) or (?1), when the recursion could match a number of
519     alternatives. If it matched one of the alternatives, but subsequently,
520     outside the recursion, there was a failure, the code tried to back up into
521     the recursion. However, because of the way PCRE is implemented, this is not
522     possible, and the result was an incorrect result from the match.
524     In order to prevent this happening, the specification of recursion has
525     been changed so that all such subpatterns are automatically treated as
526     atomic groups. Thus, for example, (?R) is treated as if it were (?>(?R)).
528     4. I had overlooked the fact that, in some locales, there are characters for
529     which isalpha() is true but neither isupper() nor islower() are true. In
530     the fr_FR locale, for instance, the \xAA and \xBA characters (ordmasculine
531     and ordfeminine) are like this. This affected the treatment of \w and \W
532     when they appeared in character classes, but not when they appeared outside
533     a character class. The bit map for "word" characters is now created
534     separately from the results of isalnum() instead of just taking it from the
535     upper, lower, and digit maps. (Plus the underscore character, of course.)
537     5. The above bug also affected the handling of POSIX character classes such as
538     [[:alpha:]] and [[:alnum:]]. These do not have their own bit maps in PCRE's
539     permanent tables. Instead, the bit maps for such a class were previously
540     created as the appropriate unions of the upper, lower, and digit bitmaps.
541     Now they are created by subtraction from the [[:word:]] class, which has
542     its own bitmap.
544     6. The [[:blank:]] character class matches horizontal, but not vertical space.
545     It is created by subtracting the vertical space characters (\x09, \x0a,
546     \x0b, \x0c) from the [[:space:]] bitmap. Previously, however, the
547     subtraction was done in the overall bitmap for a character class, meaning
548     that a class such as [\x0c[:blank:]] was incorrect because \x0c would not
549     be recognized. This bug has been fixed.
551     7. Patches from the folks at Google:
553     (a) pcrecpp.cc: "to handle a corner case that may or may not happen in
554     real life, but is still worth protecting against".
556     (b) pcrecpp.cc: "corrects a bug when negative radixes are used with
557     regular expressions".
559     (c) pcre_scanner.cc: avoid use of std::count() because not all systems
560     have it.
562     (d) Split off pcrecpparg.h from pcrecpp.h and had the former built by
563     "configure" and the latter not, in order to fix a problem somebody had
564     with compiling the Arg class on HP-UX.
566     (e) Improve the error-handling of the C++ wrapper a little bit.
568     (f) New tests for checking recursion limiting.
570     8. The pcre_memmove() function, which is used only if the environment does not
571     have a standard memmove() function (and is therefore rarely compiled),
572     contained two bugs: (a) use of int instead of size_t, and (b) it was not
573     returning a result (though PCRE never actually uses the result).
575     9. In the POSIX regexec() interface, if nmatch is specified as a ridiculously
576     large number - greater than INT_MAX/(3*sizeof(int)) - REG_ESPACE is
577     returned instead of calling malloc() with an overflowing number that would
578     most likely cause subsequent chaos.
580     10. The debugging option of pcretest was not showing the NO_AUTO_CAPTURE flag.
582     11. The POSIX flag REG_NOSUB is now supported. When a pattern that was compiled
583     with this option is matched, the nmatch and pmatch options of regexec() are
584     ignored.
586     12. Added REG_UTF8 to the POSIX interface. This is not defined by POSIX, but is
587     provided in case anyone wants to the the POSIX interface with UTF-8
588     strings.
590     13. Added CXXLDFLAGS to the Makefile parameters to provide settings only on the
591     C++ linking (needed for some HP-UX environments).
593     14. Avoid compiler warnings in get_ucpname() when compiled without UCP support
594     (unused parameter) and in the pcre_printint() function (omitted "default"
595     switch label when the default is to do nothing).
597     15. Added some code to make it possible, when PCRE is compiled as a C++
598     library, to replace subject pointers for pcre_exec() with a smart pointer
599     class, thus making it possible to process discontinuous strings.
601     16. The two macros PCRE_EXPORT and PCRE_DATA_SCOPE are confusing, and perform
602     much the same function. They were added by different people who were trying
603     to make PCRE easy to compile on non-Unix systems. It has been suggested
604     that PCRE_EXPORT be abolished now that there is more automatic apparatus
605     for compiling on Windows systems. I have therefore replaced it with
606     PCRE_DATA_SCOPE. This is set automatically for Windows; if not set it
607     defaults to "extern" for C or "extern C" for C++, which works fine on
608     Unix-like systems. It is now possible to override the value of PCRE_DATA_
609     SCOPE with something explicit in config.h. In addition:
611     (a) pcreposix.h still had just "extern" instead of either of these macros;
612     I have replaced it with PCRE_DATA_SCOPE.
614     (b) Functions such as _pcre_xclass(), which are internal to the library,
615     but external in the C sense, all had PCRE_EXPORT in their definitions.
616     This is apparently wrong for the Windows case, so I have removed it.
617     (It makes no difference on Unix-like systems.)
619     17. Added a new limit, MATCH_LIMIT_RECURSION, which limits the depth of nesting
620     of recursive calls to match(). This is different to MATCH_LIMIT because
621     that limits the total number of calls to match(), not all of which increase
622     the depth of recursion. Limiting the recursion depth limits the amount of
623     stack (or heap if NO_RECURSE is set) that is used. The default can be set
624     when PCRE is compiled, and changed at run time. A patch from Google adds
625     this functionality to the C++ interface.
627     18. Changes to the handling of Unicode character properties:
629     (a) Updated the table to Unicode 4.1.0.
631     (b) Recognize characters that are not in the table as "Cn" (undefined).
633     (c) I revised the way the table is implemented to a much improved format
634     which includes recognition of ranges. It now supports the ranges that
635     are defined in UnicodeData.txt, and it also amalgamates other
636     characters into ranges. This has reduced the number of entries in the
637     table from around 16,000 to around 3,000, thus reducing its size
638     considerably. I realized I did not need to use a tree structure after
639     all - a binary chop search is just as efficient. Having reduced the
640     number of entries, I extended their size from 6 bytes to 8 bytes to
641     allow for more data.
643     (d) Added support for Unicode script names via properties such as \p{Han}.
645     19. In UTF-8 mode, a backslash followed by a non-Ascii character was not
646     matching that character.
648     20. When matching a repeated Unicode property with a minimum greater than zero,
649     (for example \pL{2,}), PCRE could look past the end of the subject if it
650     reached it while seeking the minimum number of characters. This could
651     happen only if some of the characters were more than one byte long, because
652     there is a check for at least the minimum number of bytes.
654     21. Refactored the implementation of \p and \P so as to be more general, to
655     allow for more different types of property in future. This has changed the
656     compiled form incompatibly. Anybody with saved compiled patterns that use
657     \p or \P will have to recompile them.
659     22. Added "Any" and "L&" to the supported property types.
661     23. Recognize \x{...} as a code point specifier, even when not in UTF-8 mode,
662     but give a compile time error if the value is greater than 0xff.
664     24. The man pages for pcrepartial, pcreprecompile, and pcre_compile2 were
665     accidentally not being installed or uninstalled.
667     25. The pcre.h file was built from pcre.h.in, but the only changes that were
668     made were to insert the current release number. This seemed silly, because
669     it made things harder for people building PCRE on systems that don't run
670     "configure". I have turned pcre.h into a distributed file, no longer built
671     by "configure", with the version identification directly included. There is
672     no longer a pcre.h.in file.
674     However, this change necessitated a change to the pcre-config script as
675     well. It is built from pcre-config.in, and one of the substitutions was the
676     release number. I have updated configure.ac so that ./configure now finds
677     the release number by grepping pcre.h.
679     26. Added the ability to run the tests under valgrind.
682 nigel 85 Version 6.4 05-Sep-05
683     ---------------------
685     1. Change 6.0/10/(l) to pcregrep introduced a bug that caused separator lines
686     "--" to be printed when multiple files were scanned, even when none of the
687     -A, -B, or -C options were used. This is not compatible with Gnu grep, so I
688     consider it to be a bug, and have restored the previous behaviour.
690     2. A couple of code tidies to get rid of compiler warnings.
692     3. The pcretest program used to cheat by referring to symbols in the library
693     whose names begin with _pcre_. These are internal symbols that are not
694     really supposed to be visible externally, and in some environments it is
695     possible to suppress them. The cheating is now confined to including
696     certain files from the library's source, which is a bit cleaner.
698     4. Renamed pcre.in as pcre.h.in to go with pcrecpp.h.in; it also makes the
699     file's purpose clearer.
701     5. Reorganized pcre_ucp_findchar().
704 nigel 83 Version 6.3 15-Aug-05
705     ---------------------
707     1. The file libpcre.pc.in did not have general read permission in the tarball.
709     2. There were some problems when building without C++ support:
711     (a) If C++ support was not built, "make install" and "make test" still
712     tried to test it.
714     (b) There were problems when the value of CXX was explicitly set. Some
715     changes have been made to try to fix these, and ...
717     (c) --disable-cpp can now be used to explicitly disable C++ support.
719     (d) The use of @CPP_OBJ@ directly caused a blank line preceded by a
720     backslash in a target when C++ was disabled. This confuses some
721     versions of "make", apparently. Using an intermediate variable solves
722     this. (Same for CPP_LOBJ.)
724     3. $(LINK_FOR_BUILD) now includes $(CFLAGS_FOR_BUILD) and $(LINK)
725     (non-Windows) now includes $(CFLAGS) because these flags are sometimes
726     necessary on certain architectures.
728     4. Added a setting of -export-symbols-regex to the link command to remove
729     those symbols that are exported in the C sense, but actually are local
730     within the library, and not documented. Their names all begin with
731     "_pcre_". This is not a perfect job, because (a) we have to except some
732     symbols that pcretest ("illegally") uses, and (b) the facility isn't always
733     available (and never for static libraries). I have made a note to try to
734     find a way round (a) in the future.
737 nigel 81 Version 6.2 01-Aug-05
738     ---------------------
740     1. There was no test for integer overflow of quantifier values. A construction
741     such as {1111111111111111} would give undefined results. What is worse, if
742     a minimum quantifier for a parenthesized subpattern overflowed and became
743     negative, the calculation of the memory size went wrong. This could have
744     led to memory overwriting.
746     2. Building PCRE using VPATH was broken. Hopefully it is now fixed.
748     3. Added "b" to the 2nd argument of fopen() in dftables.c, for non-Unix-like
749     operating environments where this matters.
751     4. Applied Giuseppe Maxia's patch to add additional features for controlling
752     PCRE options from within the C++ wrapper.
754     5. Named capturing subpatterns were not being correctly counted when a pattern
755     was compiled. This caused two problems: (a) If there were more than 100
756     such subpatterns, the calculation of the memory needed for the whole
757     compiled pattern went wrong, leading to an overflow error. (b) Numerical
758     back references of the form \12, where the number was greater than 9, were
759     not recognized as back references, even though there were sufficient
760     previous subpatterns.
762     6. Two minor patches to pcrecpp.cc in order to allow it to compile on older
763     versions of gcc, e.g. 2.95.4.
766 nigel 79 Version 6.1 21-Jun-05
767     ---------------------
769     1. There was one reference to the variable "posix" in pcretest.c that was not
770     surrounded by "#if !defined NOPOSIX".
772     2. Make it possible to compile pcretest without DFA support, UTF8 support, or
773     the cross-check on the old pcre_info() function, for the benefit of the
774     cut-down version of PCRE that is currently imported into Exim.
776     3. A (silly) pattern starting with (?i)(?-i) caused an internal space
777     allocation error. I've done the easy fix, which wastes 2 bytes for sensible
778     patterns that start (?i) but I don't think that matters. The use of (?i) is
779     just an example; this all applies to the other options as well.
781     4. Since libtool seems to echo the compile commands it is issuing, the output
782     from "make" can be reduced a bit by putting "@" in front of each libtool
783     compile command.
785     5. Patch from the folks at Google for configure.in to be a bit more thorough
786     in checking for a suitable C++ installation before trying to compile the
787     C++ stuff. This should fix a reported problem when a compiler was present,
788     but no suitable headers.
790     6. The man pages all had just "PCRE" as their title. I have changed them to
791     be the relevant file name. I have also arranged that these names are
792     retained in the file doc/pcre.txt, which is a concatenation in text format
793     of all the man pages except the little individual ones for each function.
795     7. The NON-UNIX-USE file had not been updated for the different set of source
796     files that come with release 6. I also added a few comments about the C++
797     wrapper.
800 nigel 77 Version 6.0 07-Jun-05
801     ---------------------
803     1. Some minor internal re-organization to help with my DFA experiments.
805     2. Some missing #ifdef SUPPORT_UCP conditionals in pcretest and printint that
806     didn't matter for the library itself when fully configured, but did matter
807     when compiling without UCP support, or within Exim, where the ucp files are
808     not imported.
810     3. Refactoring of the library code to split up the various functions into
811     different source modules. The addition of the new DFA matching code (see
812     below) to a single monolithic source would have made it really too
813     unwieldy, quite apart from causing all the code to be include in a
814     statically linked application, when only some functions are used. This is
815     relevant even without the DFA addition now that patterns can be compiled in
816     one application and matched in another.
818     The downside of splitting up is that there have to be some external
819     functions and data tables that are used internally in different modules of
820     the library but which are not part of the API. These have all had their
821     names changed to start with "_pcre_" so that they are unlikely to clash
822     with other external names.
824     4. Added an alternate matching function, pcre_dfa_exec(), which matches using
825     a different (DFA) algorithm. Although it is slower than the original
826     function, it does have some advantages for certain types of matching
827     problem.
829     5. Upgrades to pcretest in order to test the features of pcre_dfa_exec(),
830     including restarting after a partial match.
832     6. A patch for pcregrep that defines INVALID_FILE_ATTRIBUTES if it is not
833     defined when compiling for Windows was sent to me. I have put it into the
834     code, though I have no means of testing or verifying it.
836     7. Added the pcre_refcount() auxiliary function.
838     8. Added the PCRE_FIRSTLINE option. This constrains an unanchored pattern to
839     match before or at the first newline in the subject string. In pcretest,
840     the /f option on a pattern can be used to set this.
842     9. A repeated \w when used in UTF-8 mode with characters greater than 256
843     would behave wrongly. This has been present in PCRE since release 4.0.
845     10. A number of changes to the pcregrep command:
847     (a) Refactored how -x works; insert ^(...)$ instead of setting
848     PCRE_ANCHORED and checking the length, in preparation for adding
849     something similar for -w.
851     (b) Added the -w (match as a word) option.
853     (c) Refactored the way lines are read and buffered so as to have more
854     than one at a time available.
856     (d) Implemented a pcregrep test script.
858     (e) Added the -M (multiline match) option. This allows patterns to match
859     over several lines of the subject. The buffering ensures that at least
860     8K, or the rest of the document (whichever is the shorter) is available
861     for matching (and similarly the previous 8K for lookbehind assertions).
863     (f) Changed the --help output so that it now says
865     -w, --word-regex(p)
867     instead of two lines, one with "regex" and the other with "regexp"
868     because that confused at least one person since the short forms are the
869     same. (This required a bit of code, as the output is generated
870     automatically from a table. It wasn't just a text change.)
872     (g) -- can be used to terminate pcregrep options if the next thing isn't an
873     option but starts with a hyphen. Could be a pattern or a path name
874     starting with a hyphen, for instance.
876     (h) "-" can be given as a file name to represent stdin.
878     (i) When file names are being printed, "(standard input)" is used for
879     the standard input, for compatibility with GNU grep. Previously
880     "<stdin>" was used.
882     (j) The option --label=xxx can be used to supply a name to be used for
883     stdin when file names are being printed. There is no short form.
885     (k) Re-factored the options decoding logic because we are going to add
886     two more options that take data. Such options can now be given in four
887     different ways, e.g. "-fname", "-f name", "--file=name", "--file name".
889     (l) Added the -A, -B, and -C options for requesting that lines of context
890     around matches be printed.
892     (m) Added the -L option to print the names of files that do not contain
893     any matching lines, that is, the complement of -l.
895     (n) The return code is 2 if any file cannot be opened, but pcregrep does
896     continue to scan other files.
898     (o) The -s option was incorrectly implemented. For compatibility with other
899     greps, it now suppresses the error message for a non-existent or non-
900     accessible file (but not the return code). There is a new option called
901     -q that suppresses the output of matching lines, which was what -s was
902     previously doing.
904     (p) Added --include and --exclude options to specify files for inclusion
905     and exclusion when recursing.
907     11. The Makefile was not using the Autoconf-supported LDFLAGS macro properly.
908     Hopefully, it now does.
910     12. Missing cast in pcre_study().
912     13. Added an "uninstall" target to the makefile.
914     14. Replaced "extern" in the function prototypes in Makefile.in with
915     "PCRE_DATA_SCOPE", which defaults to 'extern' or 'extern "C"' in the Unix
916     world, but is set differently for Windows.
918     15. Added a second compiling function called pcre_compile2(). The only
919     difference is that it has an extra argument, which is a pointer to an
920     integer error code. When there is a compile-time failure, this is set
921     non-zero, in addition to the error test pointer being set to point to an
922     error message. The new argument may be NULL if no error number is required
923     (but then you may as well call pcre_compile(), which is now just a
924     wrapper). This facility is provided because some applications need a
925     numeric error indication, but it has also enabled me to tidy up the way
926     compile-time errors are handled in the POSIX wrapper.
928     16. Added VPATH=.libs to the makefile; this should help when building with one
929     prefix path and installing with another. (Or so I'm told by someone who
930     knows more about this stuff than I do.)
932     17. Added a new option, REG_DOTALL, to the POSIX function regcomp(). This
933     passes PCRE_DOTALL to the pcre_compile() function, making the "." character
934     match everything, including newlines. This is not POSIX-compatible, but
935     somebody wanted the feature. From pcretest it can be activated by using
936     both the P and the s flags.
938     18. AC_PROG_LIBTOOL appeared twice in Makefile.in. Removed one.
940     19. libpcre.pc was being incorrectly installed as executable.
942     20. A couple of places in pcretest check for end-of-line by looking for '\n';
943     it now also looks for '\r' so that it will work unmodified on Windows.
945     21. Added Google's contributed C++ wrapper to the distribution.
947     22. Added some untidy missing memory free() calls in pcretest, to keep
948     Electric Fence happy when testing.
952 nigel 75 Version 5.0 13-Sep-04
953     ---------------------
955     1. Internal change: literal characters are no longer packed up into items
956     containing multiple characters in a single byte-string. Each character
957     is now matched using a separate opcode. However, there may be more than one
958     byte in the character in UTF-8 mode.
960     2. The pcre_callout_block structure has two new fields: pattern_position and
961     next_item_length. These contain the offset in the pattern to the next match
962     item, and its length, respectively.
964     3. The PCRE_AUTO_CALLOUT option for pcre_compile() requests the automatic
965     insertion of callouts before each pattern item. Added the /C option to
966     pcretest to make use of this.
968     4. On the advice of a Windows user, the lines
970     #if defined(_WIN32) || defined(WIN32)
971     _setmode( _fileno( stdout ), 0x8000 );
972     #endif /* defined(_WIN32) || defined(WIN32) */
974     have been added to the source of pcretest. This apparently does useful
975     magic in relation to line terminators.
977     5. Changed "r" and "w" in the calls to fopen() in pcretest to "rb" and "wb"
978     for the benefit of those environments where the "b" makes a difference.
980     6. The icc compiler has the same options as gcc, but "configure" doesn't seem
981     to know about it. I have put a hack into configure.in that adds in code
982     to set GCC=yes if CC=icc. This seems to end up at a point in the
983     generated configure script that is early enough to affect the setting of
984     compiler options, which is what is needed, but I have no means of testing
985     whether it really works. (The user who reported this had patched the
986     generated configure script, which of course I cannot do.)
988     LATER: After change 22 below (new libtool files), the configure script
989     seems to know about icc (and also ecc). Therefore, I have commented out
990     this hack in configure.in.
992     7. Added support for pkg-config (2 patches were sent in).
994     8. Negated POSIX character classes that used a combination of internal tables
995     were completely broken. These were [[:^alpha:]], [[:^alnum:]], and
996     [[:^ascii]]. Typically, they would match almost any characters. The other
997     POSIX classes were not broken in this way.
999     9. Matching the pattern "\b.*?" against "ab cd", starting at offset 1, failed
1000     to find the match, as PCRE was deluded into thinking that the match had to
1001     start at the start point or following a newline. The same bug applied to
1002     patterns with negative forward assertions or any backward assertions
1003     preceding ".*" at the start, unless the pattern required a fixed first
1004     character. This was a failing pattern: "(?!.bcd).*". The bug is now fixed.
1006     10. In UTF-8 mode, when moving forwards in the subject after a failed match
1007     starting at the last subject character, bytes beyond the end of the subject
1008     string were read.
1010     11. Renamed the variable "class" as "classbits" to make life easier for C++
1011     users. (Previously there was a macro definition, but it apparently wasn't
1012     enough.)
1014     12. Added the new field "tables" to the extra data so that tables can be passed
1015     in at exec time, or the internal tables can be re-selected. This allows
1016     a compiled regex to be saved and re-used at a later time by a different
1017     program that might have everything at different addresses.
1019     13. Modified the pcre-config script so that, when run on Solaris, it shows a
1020     -R library as well as a -L library.
1022     14. The debugging options of pcretest (-d on the command line or D on a
1023     pattern) showed incorrect output for anything following an extended class
1024     that contained multibyte characters and which was followed by a quantifier.
1026     15. Added optional support for general category Unicode character properties
1027     via the \p, \P, and \X escapes. Unicode property support implies UTF-8
1028     support. It adds about 90K to the size of the library. The meanings of the
1029     inbuilt class escapes such as \d and \s have NOT been changed.
1031     16. Updated pcredemo.c to include calls to free() to release the memory for the
1032     compiled pattern.
1034     17. The generated file chartables.c was being created in the source directory
1035     instead of in the building directory. This caused the build to fail if the
1036     source directory was different from the building directory, and was
1037     read-only.
1039     18. Added some sample Win commands from Mark Tetrode into the NON-UNIX-USE
1040     file. No doubt somebody will tell me if they don't make sense... Also added
1041     Dan Mooney's comments about building on OpenVMS.
1043     19. Added support for partial matching via the PCRE_PARTIAL option for
1044     pcre_exec() and the \P data escape in pcretest.
1046     20. Extended pcretest with 3 new pattern features:
1048     (i) A pattern option of the form ">rest-of-line" causes pcretest to
1049     write the compiled pattern to the file whose name is "rest-of-line".
1050     This is a straight binary dump of the data, with the saved pointer to
1051     the character tables forced to be NULL. The study data, if any, is
1052     written too. After writing, pcretest reads a new pattern.
1054     (ii) If, instead of a pattern, "<rest-of-line" is given, pcretest reads a
1055     compiled pattern from the given file. There must not be any
1056     occurrences of "<" in the file name (pretty unlikely); if there are,
1057     pcretest will instead treat the initial "<" as a pattern delimiter.
1058     After reading in the pattern, pcretest goes on to read data lines as
1059     usual.
1061     (iii) The F pattern option causes pcretest to flip the bytes in the 32-bit
1062     and 16-bit fields in a compiled pattern, to simulate a pattern that
1063     was compiled on a host of opposite endianness.
1065     21. The pcre-exec() function can now cope with patterns that were compiled on
1066     hosts of opposite endianness, with this restriction:
1068     As for any compiled expression that is saved and used later, the tables
1069     pointer field cannot be preserved; the extra_data field in the arguments
1070     to pcre_exec() should be used to pass in a tables address if a value
1071     other than the default internal tables were used at compile time.
1073     22. Calling pcre_exec() with a negative value of the "ovecsize" parameter is
1074     now diagnosed as an error. Previously, most of the time, a negative number
1075     would have been treated as zero, but if in addition "ovector" was passed as
1076     NULL, a crash could occur.
1078     23. Updated the files ltmain.sh, config.sub, config.guess, and aclocal.m4 with
1079     new versions from the libtool 1.5 distribution (the last one is a copy of
1080     a file called libtool.m4). This seems to have fixed the need to patch
1081     "configure" to support Darwin 1.3 (which I used to do). However, I still
1082     had to patch ltmain.sh to ensure that ${SED} is set (it isn't on my
1083     workstation).
1085     24. Changed the PCRE licence to be the more standard "BSD" licence.
1088 nigel 73 Version 4.5 01-Dec-03
1089     ---------------------
1091     1. There has been some re-arrangement of the code for the match() function so
1092     that it can be compiled in a version that does not call itself recursively.
1093     Instead, it keeps those local variables that need separate instances for
1094     each "recursion" in a frame on the heap, and gets/frees frames whenever it
1095     needs to "recurse". Keeping track of where control must go is done by means
1096     of setjmp/longjmp. The whole thing is implemented by a set of macros that
1097     hide most of the details from the main code, and operates only if
1098     NO_RECURSE is defined while compiling pcre.c. If PCRE is built using the
1099     "configure" mechanism, "--disable-stack-for-recursion" turns on this way of
1100     operating.
1102     To make it easier for callers to provide specially tailored get/free
1103     functions for this usage, two new functions, pcre_stack_malloc, and
1104     pcre_stack_free, are used. They are always called in strict stacking order,
1105     and the size of block requested is always the same.
1107     The PCRE_CONFIG_STACKRECURSE info parameter can be used to find out whether
1108     PCRE has been compiled to use the stack or the heap for recursion. The
1109     -C option of pcretest uses this to show which version is compiled.
1111     A new data escape \S, is added to pcretest; it causes the amounts of store
1112     obtained and freed by both kinds of malloc/free at match time to be added
1113     to the output.
1115     2. Changed the locale test to use "fr_FR" instead of "fr" because that's
1116     what's available on my current Linux desktop machine.
1118     3. When matching a UTF-8 string, the test for a valid string at the start has
1119     been extended. If start_offset is not zero, PCRE now checks that it points
1120     to a byte that is the start of a UTF-8 character. If not, it returns
1121     PCRE_ERROR_BADUTF8_OFFSET (-11). Note: the whole string is still checked;
1122     this is necessary because there may be backward assertions in the pattern.
1123     When matching the same subject several times, it may save resources to use
1124     PCRE_NO_UTF8_CHECK on all but the first call if the string is long.
1126     4. The code for checking the validity of UTF-8 strings has been tightened so
1127     that it rejects (a) strings containing 0xfe or 0xff bytes and (b) strings
1128     containing "overlong sequences".
1130     5. Fixed a bug (appearing twice) that I could not find any way of exploiting!
1131     I had written "if ((digitab[*p++] && chtab_digit) == 0)" where the "&&"
1132     should have been "&", but it just so happened that all the cases this let
1133     through by mistake were picked up later in the function.
1135     6. I had used a variable called "isblank" - this is a C99 function, causing
1136     some compilers to warn. To avoid this, I renamed it (as "blankclass").
1138     7. Cosmetic: (a) only output another newline at the end of pcretest if it is
1139     prompting; (b) run "./pcretest /dev/null" at the start of the test script
1140     so the version is shown; (c) stop "make test" echoing "./RunTest".
1142     8. Added patches from David Burgess to enable PCRE to run on EBCDIC systems.
1144     9. The prototype for memmove() for systems that don't have it was using
1145     size_t, but the inclusion of the header that defines size_t was later. I've
1146     moved the #includes for the C headers earlier to avoid this.
1148     10. Added some adjustments to the code to make it easier to compiler on certain
1149     special systems:
1151     (a) Some "const" qualifiers were missing.
1152     (b) Added the macro EXPORT before all exported functions; by default this
1153     is defined to be empty.
1154     (c) Changed the dftables auxiliary program (that builds chartables.c) so
1155     that it reads its output file name as an argument instead of writing
1156     to the standard output and assuming this can be redirected.
1158     11. In UTF-8 mode, if a recursive reference (e.g. (?1)) followed a character
1159     class containing characters with values greater than 255, PCRE compilation
1160     went into a loop.
1162     12. A recursive reference to a subpattern that was within another subpattern
1163     that had a minimum quantifier of zero caused PCRE to crash. For example,
1164     (x(y(?2))z)? provoked this bug with a subject that got as far as the
1165     recursion. If the recursively-called subpattern itself had a zero repeat,
1166     that was OK.
1168     13. In pcretest, the buffer for reading a data line was set at 30K, but the
1169     buffer into which it was copied (for escape processing) was still set at
1170     1024, so long lines caused crashes.
1172     14. A pattern such as /[ab]{1,3}+/ failed to compile, giving the error
1173     "internal error: code overflow...". This applied to any character class
1174     that was followed by a possessive quantifier.
1176     15. Modified the Makefile to add libpcre.la as a prerequisite for
1177     libpcreposix.la because I was told this is needed for a parallel build to
1178     work.
1180     16. If a pattern that contained .* following optional items at the start was
1181     studied, the wrong optimizing data was generated, leading to matching
1182     errors. For example, studying /[ab]*.*c/ concluded, erroneously, that any
1183     matching string must start with a or b or c. The correct conclusion for
1184     this pattern is that a match can start with any character.
1187 nigel 71 Version 4.4 13-Aug-03
1188     ---------------------
1190     1. In UTF-8 mode, a character class containing characters with values between
1191     127 and 255 was not handled correctly if the compiled pattern was studied.
1192     In fixing this, I have also improved the studying algorithm for such
1193     classes (slightly).
1195     2. Three internal functions had redundant arguments passed to them. Removal
1196     might give a very teeny performance improvement.
1198     3. Documentation bug: the value of the capture_top field in a callout is *one
1199     more than* the number of the hightest numbered captured substring.
1201     4. The Makefile linked pcretest and pcregrep with -lpcre, which could result
1202     in incorrectly linking with a previously installed version. They now link
1203     explicitly with libpcre.la.
1205     5. configure.in no longer needs to recognize Cygwin specially.
1207     6. A problem in pcre.in for Windows platforms is fixed.
1209     7. If a pattern was successfully studied, and the -d (or /D) flag was given to
1210     pcretest, it used to include the size of the study block as part of its
1211     output. Unfortunately, the structure contains a field that has a different
1212     size on different hardware architectures. This meant that the tests that
1213     showed this size failed. As the block is currently always of a fixed size,
1214     this information isn't actually particularly useful in pcretest output, so
1215     I have just removed it.
1217     8. Three pre-processor statements accidentally did not start in column 1.
1218     Sadly, there are *still* compilers around that complain, even though
1219     standard C has not required this for well over a decade. Sigh.
1221     9. In pcretest, the code for checking callouts passed small integers in the
1222     callout_data field, which is a void * field. However, some picky compilers
1223     complained about the casts involved for this on 64-bit systems. Now
1224     pcretest passes the address of the small integer instead, which should get
1225     rid of the warnings.
1227     10. By default, when in UTF-8 mode, PCRE now checks for valid UTF-8 strings at
1228     both compile and run time, and gives an error if an invalid UTF-8 sequence
1229     is found. There is a option for disabling this check in cases where the
1230     string is known to be correct and/or the maximum performance is wanted.
1232     11. In response to a bug report, I changed one line in Makefile.in from
1234     -Wl,--out-implib,.libs/lib@WIN_PREFIX@pcreposix.dll.a \
1235     to
1236     -Wl,--out-implib,.libs/@WIN_PREFIX@libpcreposix.dll.a \
1238     to look similar to other lines, but I have no way of telling whether this
1239     is the right thing to do, as I do not use Windows. No doubt I'll get told
1240     if it's wrong...
1243 nigel 69 Version 4.3 21-May-03
1244     ---------------------
1246     1. Two instances of @WIN_PREFIX@ omitted from the Windows targets in the
1247     Makefile.
1249     2. Some refactoring to improve the quality of the code:
1251     (i) The utf8_table... variables are now declared "const".
1253     (ii) The code for \cx, which used the "case flipping" table to upper case
1254     lower case letters, now just substracts 32. This is ASCII-specific,
1255     but the whole concept of \cx is ASCII-specific, so it seems
1256     reasonable.
1258     (iii) PCRE was using its character types table to recognize decimal and
1259     hexadecimal digits in the pattern. This is silly, because it handles
1260     only 0-9, a-f, and A-F, but the character types table is locale-
1261     specific, which means strange things might happen. A private
1262     table is now used for this - though it costs 256 bytes, a table is
1263     much faster than multiple explicit tests. Of course, the standard
1264     character types table is still used for matching digits in subject
1265     strings against \d.
1267     (iv) Strictly, the identifier ESC_t is reserved by POSIX (all identifiers
1268     ending in _t are). So I've renamed it as ESC_tee.
1270     3. The first argument for regexec() in the POSIX wrapper should have been
1271     defined as "const".
1273     4. Changed pcretest to use malloc() for its buffers so that they can be
1274     Electric Fenced for debugging.
1276     5. There were several places in the code where, in UTF-8 mode, PCRE would try
1277     to read one or more bytes before the start of the subject string. Often this
1278     had no effect on PCRE's behaviour, but in some circumstances it could
1279     provoke a segmentation fault.
1281     6. A lookbehind at the start of a pattern in UTF-8 mode could also cause PCRE
1282     to try to read one or more bytes before the start of the subject string.
1284     7. A lookbehind in a pattern matched in non-UTF-8 mode on a PCRE compiled with
1285     UTF-8 support could misbehave in various ways if the subject string
1286     contained bytes with the 0x80 bit set and the 0x40 bit unset in a lookbehind
1287     area. (PCRE was not checking for the UTF-8 mode flag, and trying to move
1288     back over UTF-8 characters.)
1291 nigel 67 Version 4.2 14-Apr-03
1292     ---------------------
1294     1. Typo "#if SUPPORT_UTF8" instead of "#ifdef SUPPORT_UTF8" fixed.
1296     2. Changes to the building process, supplied by Ronald Landheer-Cieslak
1297     [ON_WINDOWS]: new variable, "#" on non-Windows platforms
1298     [NOT_ON_WINDOWS]: new variable, "#" on Windows platforms
1299     [WIN_PREFIX]: new variable, "cyg" for Cygwin
1300     * Makefile.in: use autoconf substitution for OBJEXT, EXEEXT, BUILD_OBJEXT
1301     and BUILD_EXEEXT
1302     Note: automatic setting of the BUILD variables is not yet working
1303     set CPPFLAGS and BUILD_CPPFLAGS (but don't use yet) - should be used at
1304     compile-time but not at link-time
1305     [LINK]: use for linking executables only
1306     make different versions for Windows and non-Windows
1307     [LINKLIB]: new variable, copy of UNIX-style LINK, used for linking
1308     libraries
1309     [LINK_FOR_BUILD]: new variable
1310     [OBJEXT]: use throughout
1311     [EXEEXT]: use throughout
1312     <winshared>: new target
1313     <wininstall>: new target
1314     <dftables.o>: use native compiler
1315     <dftables>: use native linker
1316     <install>: handle Windows platform correctly
1317     <clean>: ditto
1318     <check>: ditto
1319     copy DLL to top builddir before testing
1321     As part of these changes, -no-undefined was removed again. This was reported
1322     to give trouble on HP-UX 11.0, so getting rid of it seems like a good idea
1323     in any case.
1325     3. Some tidies to get rid of compiler warnings:
1327     . In the match_data structure, match_limit was an unsigned long int, whereas
1328     match_call_count was an int. I've made them both unsigned long ints.
1330     . In pcretest the fact that a const uschar * doesn't automatically cast to
1331     a void * provoked a warning.
1333     . Turning on some more compiler warnings threw up some "shadow" variables
1334     and a few more missing casts.
1336     4. If PCRE was complied with UTF-8 support, but called without the PCRE_UTF8
1337     option, a class that contained a single character with a value between 128
1338     and 255 (e.g. /[\xFF]/) caused PCRE to crash.
1340     5. If PCRE was compiled with UTF-8 support, but called without the PCRE_UTF8
1341     option, a class that contained several characters, but with at least one
1342     whose value was between 128 and 255 caused PCRE to crash.
1345 nigel 65 Version 4.1 12-Mar-03
1346     ---------------------
1347 nigel 63
1348 nigel 65 1. Compiling with gcc -pedantic found a couple of places where casts were
1349     needed, and a string in dftables.c that was longer than standard compilers are
1350     required to support.
1352     2. Compiling with Sun's compiler found a few more places where the code could
1353     be tidied up in order to avoid warnings.
1355     3. The variables for cross-compiling were called HOST_CC and HOST_CFLAGS; the
1356     first of these names is deprecated in the latest Autoconf in favour of the name
1357     CC_FOR_BUILD, because "host" is typically used to mean the system on which the
1358     compiled code will be run. I can't find a reference for HOST_CFLAGS, but by
1359     analogy I have changed it to CFLAGS_FOR_BUILD.
1361     4. Added -no-undefined to the linking command in the Makefile, because this is
1362     apparently helpful for Windows. To make it work, also added "-L. -lpcre" to the
1363     linking step for the pcreposix library.
1365     5. PCRE was failing to diagnose the case of two named groups with the same
1366     name.
1368     6. A problem with one of PCRE's optimizations was discovered. PCRE remembers a
1369     literal character that is needed in the subject for a match, and scans along to
1370     ensure that it is present before embarking on the full matching process. This
1371     saves time in cases of nested unlimited repeats that are never going to match.
1372     Problem: the scan can take a lot of time if the subject is very long (e.g.
1373     megabytes), thus penalizing straightforward matches. It is now done only if the
1374     amount of subject to be scanned is less than 1000 bytes.
1376     7. A lesser problem with the same optimization is that it was recording the
1377     first character of an anchored pattern as "needed", thus provoking a search
1378     right along the subject, even when the first match of the pattern was going to
1379     fail. The "needed" character is now not set for anchored patterns, unless it
1380     follows something in the pattern that is of non-fixed length. Thus, it still
1381     fulfils its original purpose of finding quick non-matches in cases of nested
1382     unlimited repeats, but isn't used for simple anchored patterns such as /^abc/.
1385     Version 4.0 17-Feb-03
1386     ---------------------
1388 nigel 63 1. If a comment in an extended regex that started immediately after a meta-item
1389     extended to the end of string, PCRE compiled incorrect data. This could lead to
1390     all kinds of weird effects. Example: /#/ was bad; /()#/ was bad; /a#/ was not.
1392     2. Moved to autoconf 2.53 and libtool 1.4.2.
1394     3. Perl 5.8 no longer needs "use utf8" for doing UTF-8 things. Consequently,
1395     the special perltest8 script is no longer needed - all the tests can be run
1396     from a single perltest script.
1398     4. From 5.004, Perl has not included the VT character (0x0b) in the set defined
1399     by \s. It has now been removed in PCRE. This means it isn't recognized as
1400     whitespace in /x regexes too, which is the same as Perl. Note that the POSIX
1401     class [:space:] *does* include VT, thereby creating a mess.
1403     5. Added the class [:blank:] (a GNU extension from Perl 5.8) to match only
1404     space and tab.
1406     6. Perl 5.005 was a long time ago. It's time to amalgamate the tests that use
1407     its new features into the main test script, reducing the number of scripts.
1409     7. Perl 5.8 has changed the meaning of patterns like /a(?i)b/. Earlier versions
1410     were backward compatible, and made the (?i) apply to the whole pattern, as if
1411     /i were given. Now it behaves more logically, and applies the option setting
1412     only to what follows. PCRE has been changed to follow suit. However, if it
1413     finds options settings right at the start of the pattern, it extracts them into
1414     the global options, as before. Thus, they show up in the info data.
1416     8. Added support for the \Q...\E escape sequence. Characters in between are
1417     treated as literals. This is slightly different from Perl in that $ and @ are
1418     also handled as literals inside the quotes. In Perl, they will cause variable
1419     interpolation. Note the following examples:
1421     Pattern PCRE matches Perl matches
1423     \Qabc$xyz\E abc$xyz abc followed by the contents of $xyz
1424     \Qabc\$xyz\E abc\$xyz abc\$xyz
1425     \Qabc\E\$\Qxyz\E abc$xyz abc$xyz
1427     For compatibility with Perl, \Q...\E sequences are recognized inside character
1428     classes as well as outside them.
1430     9. Re-organized 3 code statements in pcretest to avoid "overflow in
1431     floating-point constant arithmetic" warnings from a Microsoft compiler. Added a
1432     (size_t) cast to one statement in pcretest and one in pcreposix to avoid
1433     signed/unsigned warnings.
1435     10. SunOS4 doesn't have strtoul(). This was used only for unpicking the -o
1436     option for pcretest, so I've replaced it by a simple function that does just
1437     that job.
1439     11. pcregrep was ending with code 0 instead of 2 for the commands "pcregrep" or
1440     "pcregrep -".
1442     12. Added "possessive quantifiers" ?+, *+, ++, and {,}+ which come from Sun's
1443     Java package. This provides some syntactic sugar for simple cases of what my
1444     documentation calls "once-only subpatterns". A pattern such as x*+ is the same
1445     as (?>x*). In other words, if what is inside (?>...) is just a single repeated
1446     item, you can use this simplified notation. Note that only makes sense with
1447     greedy quantifiers. Consequently, the use of the possessive quantifier forces
1448     greediness, whatever the setting of the PCRE_UNGREEDY option.
1450     13. A change of greediness default within a pattern was not taking effect at
1451     the current level for patterns like /(b+(?U)a+)/. It did apply to parenthesized
1452     subpatterns that followed. Patterns like /b+(?U)a+/ worked because the option
1453     was abstracted outside.
1455     14. PCRE now supports the \G assertion. It is true when the current matching
1456     position is at the start point of the match. This differs from \A when the
1457     starting offset is non-zero. Used with the /g option of pcretest (or similar
1458     code), it works in the same way as it does for Perl's /g option. If all
1459     alternatives of a regex begin with \G, the expression is anchored to the start
1460     match position, and the "anchored" flag is set in the compiled expression.
1462     15. Some bugs concerning the handling of certain option changes within patterns
1463     have been fixed. These applied to options other than (?ims). For example,
1464     "a(?x: b c )d" did not match "XabcdY" but did match "Xa b c dY". It should have
1465     been the other way round. Some of this was related to change 7 above.
1467     16. PCRE now gives errors for /[.x.]/ and /[=x=]/ as unsupported POSIX
1468     features, as Perl does. Previously, PCRE gave the warnings only for /[[.x.]]/
1469     and /[[=x=]]/. PCRE now also gives an error for /[:name:]/ because it supports
1470     POSIX classes only within a class (e.g. /[[:alpha:]]/).
1472     17. Added support for Perl's \C escape. This matches one byte, even in UTF8
1473     mode. Unlike ".", it always matches newline, whatever the setting of
1474     PCRE_DOTALL. However, PCRE does not permit \C to appear in lookbehind
1475     assertions. Perl allows it, but it doesn't (in general) work because it can't
1476     calculate the length of the lookbehind. At least, that's the case for Perl
1477     5.8.0 - I've been told they are going to document that it doesn't work in
1478     future.
1480     18. Added an error diagnosis for escapes that PCRE does not support: these are
1481     \L, \l, \N, \P, \p, \U, \u, and \X.
1483     19. Although correctly diagnosing a missing ']' in a character class, PCRE was
1484     reading past the end of the pattern in cases such as /[abcd/.
1486     20. PCRE was getting more memory than necessary for patterns with classes that
1487     contained both POSIX named classes and other characters, e.g. /[[:space:]abc/.
1489     21. Added some code, conditional on #ifdef VPCOMPAT, to make life easier for
1490     compiling PCRE for use with Virtual Pascal.
1492     22. Small fix to the Makefile to make it work properly if the build is done
1493     outside the source tree.
1495     23. Added a new extension: a condition to go with recursion. If a conditional
1496     subpattern starts with (?(R) the "true" branch is used if recursion has
1497     happened, whereas the "false" branch is used only at the top level.
1499     24. When there was a very long string of literal characters (over 255 bytes
1500     without UTF support, over 250 bytes with UTF support), the computation of how
1501     much memory was required could be incorrect, leading to segfaults or other
1502     strange effects.
1504     25. PCRE was incorrectly assuming anchoring (either to start of subject or to
1505     start of line for a non-DOTALL pattern) when a pattern started with (.*) and
1506     there was a subsequent back reference to those brackets. This meant that, for
1507     example, /(.*)\d+\1/ failed to match "abc123bc". Unfortunately, it isn't
1508     possible to check for precisely this case. All we can do is abandon the
1509     optimization if .* occurs inside capturing brackets when there are any back
1510     references whatsoever. (See below for a better fix that came later.)
1512     26. The handling of the optimization for finding the first character of a
1513     non-anchored pattern, and for finding a character that is required later in the
1514     match were failing in some cases. This didn't break the matching; it just
1515     failed to optimize when it could. The way this is done has been re-implemented.
1517     27. Fixed typo in error message for invalid (?R item (it said "(?p").
1519     28. Added a new feature that provides some of the functionality that Perl
1520     provides with (?{...}). The facility is termed a "callout". The way it is done
1521     in PCRE is for the caller to provide an optional function, by setting
1522     pcre_callout to its entry point. Like pcre_malloc and pcre_free, this is a
1523     global variable. By default it is unset, which disables all calling out. To get
1524     the function called, the regex must include (?C) at appropriate points. This
1525     is, in fact, equivalent to (?C0), and any number <= 255 may be given with (?C).
1526     This provides a means of identifying different callout points. When PCRE
1527     reaches such a point in the regex, if pcre_callout has been set, the external
1528     function is called. It is provided with data in a structure called
1529     pcre_callout_block, which is defined in pcre.h. If the function returns 0,
1530     matching continues; if it returns a non-zero value, the match at the current
1531     point fails. However, backtracking will occur if possible. [This was changed
1532     later and other features added - see item 49 below.]
1534     29. pcretest is upgraded to test the callout functionality. It provides a
1535     callout function that displays information. By default, it shows the start of
1536     the match and the current position in the text. There are some new data escapes
1537     to vary what happens:
1539     \C+ in addition, show current contents of captured substrings
1540     \C- do not supply a callout function
1541     \C!n return 1 when callout number n is reached
1542     \C!n!m return 1 when callout number n is reached for the mth time
1544     30. If pcregrep was called with the -l option and just a single file name, it
1545     output "<stdin>" if a match was found, instead of the file name.
1547     31. Improve the efficiency of the POSIX API to PCRE. If the number of capturing
1548     slots is less than POSIX_MALLOC_THRESHOLD, use a block on the stack to pass to
1549     pcre_exec(). This saves a malloc/free per call. The default value of
1550     POSIX_MALLOC_THRESHOLD is 10; it can be changed by --with-posix-malloc-threshold
1551     when configuring.
1553     32. The default maximum size of a compiled pattern is 64K. There have been a
1554     few cases of people hitting this limit. The code now uses macros to handle the
1555     storing of links as offsets within the compiled pattern. It defaults to 2-byte
1556     links, but this can be changed to 3 or 4 bytes by --with-link-size when
1557     configuring. Tests 2 and 5 work only with 2-byte links because they output
1558     debugging information about compiled patterns.
1560     33. Internal code re-arrangements:
1562     (a) Moved the debugging function for printing out a compiled regex into
1563     its own source file (printint.c) and used #include to pull it into
1564     pcretest.c and, when DEBUG is defined, into pcre.c, instead of having two
1565     separate copies.
1567     (b) Defined the list of op-code names for debugging as a macro in
1568     internal.h so that it is next to the definition of the opcodes.
1570     (c) Defined a table of op-code lengths for simpler skipping along compiled
1571     code. This is again a macro in internal.h so that it is next to the
1572     definition of the opcodes.
1574     34. Added support for recursive calls to individual subpatterns, along the
1575     lines of Robin Houston's patch (but implemented somewhat differently).
1577     35. Further mods to the Makefile to help Win32. Also, added code to pcregrep to
1578     allow it to read and process whole directories in Win32. This code was
1579     contributed by Lionel Fourquaux; it has not been tested by me.
1581     36. Added support for named subpatterns. The Python syntax (?P<name>...) is
1582     used to name a group. Names consist of alphanumerics and underscores, and must
1583     be unique. Back references use the syntax (?P=name) and recursive calls use
1584     (?P>name) which is a PCRE extension to the Python extension. Groups still have
1585     numbers. The function pcre_fullinfo() can be used after compilation to extract
1586     a name/number map. There are three relevant calls:
1588     PCRE_INFO_NAMEENTRYSIZE yields the size of each entry in the map
1589     PCRE_INFO_NAMECOUNT yields the number of entries
1590     PCRE_INFO_NAMETABLE yields a pointer to the map.
1592     The map is a vector of fixed-size entries. The size of each entry depends on
1593     the length of the longest name used. The first two bytes of each entry are the
1594     group number, most significant byte first. There follows the corresponding
1595     name, zero terminated. The names are in alphabetical order.
1597     37. Make the maximum literal string in the compiled code 250 for the non-UTF-8
1598     case instead of 255. Making it the same both with and without UTF-8 support
1599     means that the same test output works with both.
1601     38. There was a case of malloc(0) in the POSIX testing code in pcretest. Avoid
1602     calling malloc() with a zero argument.
1604     39. Change 25 above had to resort to a heavy-handed test for the .* anchoring
1605     optimization. I've improved things by keeping a bitmap of backreferences with
1606     numbers 1-31 so that if .* occurs inside capturing brackets that are not in
1607     fact referenced, the optimization can be applied. It is unlikely that a
1608     relevant occurrence of .* (i.e. one which might indicate anchoring or forcing
1609     the match to follow \n) will appear inside brackets with a number greater than
1610     31, but if it does, any back reference > 31 suppresses the optimization.
1612     40. Added a new compile-time option PCRE_NO_AUTO_CAPTURE. This has the effect
1613     of disabling numbered capturing parentheses. Any opening parenthesis that is
1614     not followed by ? behaves as if it were followed by ?: but named parentheses
1615     can still be used for capturing (and they will acquire numbers in the usual
1616     way).
1618     41. Redesigned the return codes from the match() function into yes/no/error so
1619     that errors can be passed back from deep inside the nested calls. A malloc
1620     failure while inside a recursive subpattern call now causes the
1621     PCRE_ERROR_NOMEMORY return instead of quietly going wrong.
1623     42. It is now possible to set a limit on the number of times the match()
1624     function is called in a call to pcre_exec(). This facility makes it possible to
1625     limit the amount of recursion and backtracking, though not in a directly
1626     obvious way, because the match() function is used in a number of different
1627     circumstances. The count starts from zero for each position in the subject
1628     string (for non-anchored patterns). The default limit is, for compatibility, a
1629     large number, namely 10 000 000. You can change this in two ways:
1631     (a) When configuring PCRE before making, you can use --with-match-limit=n
1632     to set a default value for the compiled library.
1634     (b) For each call to pcre_exec(), you can pass a pcre_extra block in which
1635     a different value is set. See 45 below.
1637     If the limit is exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT.
1639     43. Added a new function pcre_config(int, void *) to enable run-time extraction
1640     of things that can be changed at compile time. The first argument specifies
1641     what is wanted and the second points to where the information is to be placed.
1642     The current list of available information is:
1646     The output is an integer that is set to one if UTF-8 support is available;
1647     otherwise it is set to zero.
1651     The output is an integer that it set to the value of the code that is used for
1652     newline. It is either LF (10) or CR (13).
1656     The output is an integer that contains the number of bytes used for internal
1657     linkage in compiled expressions. The value is 2, 3, or 4. See item 32 above.
1661     The output is an integer that contains the threshold above which the POSIX
1662     interface uses malloc() for output vectors. See item 31 above.
1666     The output is an unsigned integer that contains the default limit of the number
1667     of match() calls in a pcre_exec() execution. See 42 above.
1669     44. pcretest has been upgraded by the addition of the -C option. This causes it
1670     to extract all the available output from the new pcre_config() function, and to
1671     output it. The program then exits immediately.
1673     45. A need has arisen to pass over additional data with calls to pcre_exec() in
1674     order to support additional features. One way would have been to define
1675     pcre_exec2() (for example) with extra arguments, but this would not have been
1676     extensible, and would also have required all calls to the original function to
1677     be mapped to the new one. Instead, I have chosen to extend the mechanism that
1678     is used for passing in "extra" data from pcre_study().
1680     The pcre_extra structure is now exposed and defined in pcre.h. It currently
1681     contains the following fields:
1683     flags a bitmap indicating which of the following fields are set
1684     study_data opaque data from pcre_study()
1685     match_limit a way of specifying a limit on match() calls for a specific
1686     call to pcre_exec()
1687     callout_data data for callouts (see 49 below)
1689     The flag bits are also defined in pcre.h, and are
1695     The pcre_study() function now returns one of these new pcre_extra blocks, with
1696     the actual study data pointed to by the study_data field, and the
1697     PCRE_EXTRA_STUDY_DATA flag set. This can be passed directly to pcre_exec() as
1698     before. That is, this change is entirely upwards-compatible and requires no
1699     change to existing code.
1701     If you want to pass in additional data to pcre_exec(), you can either place it
1702     in a pcre_extra block provided by pcre_study(), or create your own pcre_extra
1703     block.
1705     46. pcretest has been extended to test the PCRE_EXTRA_MATCH_LIMIT feature. If a
1706     data string contains the escape sequence \M, pcretest calls pcre_exec() several
1707     times with different match limits, until it finds the minimum value needed for
1708     pcre_exec() to complete. The value is then output. This can be instructive; for
1709     most simple matches the number is quite small, but for pathological cases it
1710     gets very large very quickly.
1712     47. There's a new option for pcre_fullinfo() called PCRE_INFO_STUDYSIZE. It
1713     returns the size of the data block pointed to by the study_data field in a
1714     pcre_extra block, that is, the value that was passed as the argument to
1715     pcre_malloc() when PCRE was getting memory in which to place the information
1716     created by pcre_study(). The fourth argument should point to a size_t variable.
1717     pcretest has been extended so that this information is shown after a successful
1718     pcre_study() call when information about the compiled regex is being displayed.
1720     48. Cosmetic change to Makefile: there's no need to have / after $(DESTDIR)
1721     because what follows is always an absolute path. (Later: it turns out that this
1722     is more than cosmetic for MinGW, because it doesn't like empty path
1723     components.)
1725     49. Some changes have been made to the callout feature (see 28 above):
1727     (i) A callout function now has three choices for what it returns:
1729     0 => success, carry on matching
1730     > 0 => failure at this point, but backtrack if possible
1731     < 0 => serious error, return this value from pcre_exec()
1733     Negative values should normally be chosen from the set of PCRE_ERROR_xxx
1734     values. In particular, returning PCRE_ERROR_NOMATCH forces a standard
1735     "match failed" error. The error number PCRE_ERROR_CALLOUT is reserved for
1736     use by callout functions. It will never be used by PCRE itself.
1738     (ii) The pcre_extra structure (see 45 above) has a void * field called
1739     callout_data, with corresponding flag bit PCRE_EXTRA_CALLOUT_DATA. The
1740     pcre_callout_block structure has a field of the same name. The contents of
1741     the field passed in the pcre_extra structure are passed to the callout
1742     function in the corresponding field in the callout block. This makes it
1743     easier to use the same callout-containing regex from multiple threads. For
1744     testing, the pcretest program has a new data escape
1746     \C*n pass the number n (may be negative) as callout_data
1748     If the callout function in pcretest receives a non-zero value as
1749     callout_data, it returns that value.
1751     50. Makefile wasn't handling CFLAGS properly when compiling dftables. Also,
1752     there were some redundant $(CFLAGS) in commands that are now specified as
1753     $(LINK), which already includes $(CFLAGS).
1755     51. Extensions to UTF-8 support are listed below. These all apply when (a) PCRE
1756     has been compiled with UTF-8 support *and* pcre_compile() has been compiled
1757     with the PCRE_UTF8 flag. Patterns that are compiled without that flag assume
1758     one-byte characters throughout. Note that case-insensitive matching applies
1759     only to characters whose values are less than 256. PCRE doesn't support the
1760     notion of cases for higher-valued characters.
1762     (i) A character class whose characters are all within 0-255 is handled as
1763     a bit map, and the map is inverted for negative classes. Previously, a
1764     character > 255 always failed to match such a class; however it should
1765     match if the class was a negative one (e.g. [^ab]). This has been fixed.
1767     (ii) A negated character class with a single character < 255 is coded as
1768     "not this character" (OP_NOT). This wasn't working properly when the test
1769     character was multibyte, either singly or repeated.
1771     (iii) Repeats of multibyte characters are now handled correctly in UTF-8
1772     mode, for example: \x{100}{2,3}.
1774     (iv) The character escapes \b, \B, \d, \D, \s, \S, \w, and \W (either
1775     singly or repeated) now correctly test multibyte characters. However,
1776     PCRE doesn't recognize any characters with values greater than 255 as
1777     digits, spaces, or word characters. Such characters always match \D, \S,
1778     and \W, and never match \d, \s, or \w.
1780     (v) Classes may now contain characters and character ranges with values
1781     greater than 255. For example: [ab\x{100}-\x{400}].
1783     (vi) pcregrep now has a --utf-8 option (synonym -u) which makes it call
1784     PCRE in UTF-8 mode.
1786     52. The info request value PCRE_INFO_FIRSTCHAR has been renamed
1787     PCRE_INFO_FIRSTBYTE because it is a byte value. However, the old name is
1788     retained for backwards compatibility. (Note that LASTLITERAL is also a byte
1789     value.)
1791     53. The single man page has become too large. I have therefore split it up into
1792     a number of separate man pages. These also give rise to individual HTML pages;
1793     these are now put in a separate directory, and there is an index.html page that
1794     lists them all. Some hyperlinking between the pages has been installed.
1796     54. Added convenience functions for handling named capturing parentheses.
1798     55. Unknown escapes inside character classes (e.g. [\M]) and escapes that
1799     aren't interpreted therein (e.g. [\C]) are literals in Perl. This is now also
1800     true in PCRE, except when the PCRE_EXTENDED option is set, in which case they
1801     are faulted.
1803     56. Introduced HOST_CC and HOST_CFLAGS which can be set in the environment when
1804     calling configure. These values are used when compiling the dftables.c program
1805     which is run to generate the source of the default character tables. They
1806     default to the values of CC and CFLAGS. If you are cross-compiling PCRE,
1807     you will need to set these values.
1809     57. Updated the building process for Windows DLL, as provided by Fred Cox.
1812     Version 3.9 02-Jan-02
1813 nigel 61 ---------------------
1815     1. A bit of extraneous text had somehow crept into the pcregrep documentation.
1817     2. If --disable-static was given, the building process failed when trying to
1818     build pcretest and pcregrep. (For some reason it was using libtool to compile
1819     them, which is not right, as they aren't part of the library.)
1822 nigel 59 Version 3.8 18-Dec-01
1823     ---------------------
1825     1. The experimental UTF-8 code was completely screwed up. It was packing the
1826     bytes in the wrong order. How dumb can you get?
1829 nigel 57 Version 3.7 29-Oct-01
1830     ---------------------
1832     1. In updating pcretest to check change 1 of version 3.6, I screwed up.
1833     This caused pcretest, when used on the test data, to segfault. Unfortunately,
1834     this didn't happen under Solaris 8, where I normally test things.
1836 nigel 59 2. The Makefile had to be changed to make it work on BSD systems, where 'make'
1837     doesn't seem to recognize that ./xxx and xxx are the same file. (This entry
1838     isn't in ChangeLog distributed with 3.7 because I forgot when I hastily made
1839     this fix an hour or so after the initial 3.7 release.)
1840 nigel 57
1841 nigel 59
1842 nigel 55 Version 3.6 23-Oct-01
1843     ---------------------
1845     1. Crashed with /(sens|respons)e and \1ibility/ and "sense and sensibility" if
1846     offsets passed as NULL with zero offset count.
1848     2. The config.guess and config.sub files had not been updated when I moved to
1849     the latest autoconf.
1852 nigel 53 Version 3.5 15-Aug-01
1853     ---------------------
1854 nigel 5
1855 nigel 53 1. Added some missing #if !defined NOPOSIX conditionals in pcretest.c that
1856     had been forgotten.
1858     2. By using declared but undefined structures, we can avoid using "void"
1859     definitions in pcre.h while keeping the internal definitions of the structures
1860     private.
1862     3. The distribution is now built using autoconf 2.50 and libtool 1.4. From a
1863     user point of view, this means that both static and shared libraries are built
1864     by default, but this can be individually controlled. More of the work of
1865     handling this static/shared cases is now inside libtool instead of PCRE's make
1866     file.
1868     4. The pcretest utility is now installed along with pcregrep because it is
1869     useful for users (to test regexs) and by doing this, it automatically gets
1870     relinked by libtool. The documentation has been turned into a man page, so
1871     there are now .1, .txt, and .html versions in /doc.
1873     5. Upgrades to pcregrep:
1874     (i) Added long-form option names like gnu grep.
1875     (ii) Added --help to list all options with an explanatory phrase.
1876     (iii) Added -r, --recursive to recurse into sub-directories.
1877     (iv) Added -f, --file to read patterns from a file.
1879     6. pcre_exec() was referring to its "code" argument before testing that
1880     argument for NULL (and giving an error if it was NULL).
1882     7. Upgraded Makefile.in to allow for compiling in a different directory from
1883     the source directory.
1885     8. Tiny buglet in pcretest: when pcre_fullinfo() was called to retrieve the
1886     options bits, the pointer it was passed was to an int instead of to an unsigned
1887     long int. This mattered only on 64-bit systems.
1889     9. Fixed typo (3.4/1) in pcre.h again. Sigh. I had changed pcre.h (which is
1890     generated) instead of pcre.in, which it its source. Also made the same change
1891     in several of the .c files.
1893     10. A new release of gcc defines printf() as a macro, which broke pcretest
1894     because it had an ifdef in the middle of a string argument for printf(). Fixed
1895     by using separate calls to printf().
1897     11. Added --enable-newline-is-cr and --enable-newline-is-lf to the configure
1898     script, to force use of CR or LF instead of \n in the source. On non-Unix
1899     systems, the value can be set in config.h.
1901     12. The limit of 200 on non-capturing parentheses is a _nesting_ limit, not an
1902     absolute limit. Changed the text of the error message to make this clear, and
1903     likewise updated the man page.
1905     13. The limit of 99 on the number of capturing subpatterns has been removed.
1906     The new limit is 65535, which I hope will not be a "real" limit.
1909 nigel 51 Version 3.4 22-Aug-00
1910     ---------------------
1912     1. Fixed typo in pcre.h: unsigned const char * changed to const unsigned char *.
1914     2. Diagnose condition (?(0) as an error instead of crashing on matching.
1917 nigel 49 Version 3.3 01-Aug-00
1918     ---------------------
1920     1. If an octal character was given, but the value was greater than \377, it
1921     was not getting masked to the least significant bits, as documented. This could
1922     lead to crashes in some systems.
1924     2. Perl 5.6 (if not earlier versions) accepts classes like [a-\d] and treats
1925     the hyphen as a literal. PCRE used to give an error; it now behaves like Perl.
1927     3. Added the functions pcre_free_substring() and pcre_free_substring_list().
1928     These just pass their arguments on to (pcre_free)(), but they are provided
1929     because some uses of PCRE bind it to non-C systems that can call its functions,
1930     but cannot call free() or pcre_free() directly.
1932     4. Add "make test" as a synonym for "make check". Corrected some comments in
1933     the Makefile.
1935     5. Add $(DESTDIR)/ in front of all the paths in the "install" target in the
1936     Makefile.
1938     6. Changed the name of pgrep to pcregrep, because Solaris has introduced a
1939     command called pgrep for grepping around the active processes.
1941     7. Added the beginnings of support for UTF-8 character strings.
1943     8. Arranged for the Makefile to pass over the settings of CC, CFLAGS, and
1944     RANLIB to ./ltconfig so that they are used by libtool. I think these are all
1945     the relevant ones. (AR is not passed because ./ltconfig does its own figuring
1946     out for the ar command.)
1949 nigel 47 Version 3.2 12-May-00
1950     ---------------------
1952     This is purely a bug fixing release.
1954     1. If the pattern /((Z)+|A)*/ was matched agained ZABCDEFG it matched Z instead
1955     of ZA. This was just one example of several cases that could provoke this bug,
1956     which was introduced by change 9 of version 2.00. The code for breaking
1957     infinite loops after an iteration that matches an empty string was't working
1958     correctly.
1960     2. The pcretest program was not imitating Perl correctly for the pattern /a*/g
1961     when matched against abbab (for example). After matching an empty string, it
1962     wasn't forcing anchoring when setting PCRE_NOTEMPTY for the next attempt; this
1963     caused it to match further down the string than it should.
1965     3. The code contained an inclusion of sys/types.h. It isn't clear why this
1966     was there because it doesn't seem to be needed, and it causes trouble on some
1967     systems, as it is not a Standard C header. It has been removed.
1969     4. Made 4 silly changes to the source to avoid stupid compiler warnings that
1970     were reported on the Macintosh. The changes were from
1972     while ((c = *(++ptr)) != 0 && c != '\n');
1973     to
1974     while ((c = *(++ptr)) != 0 && c != '\n') ;
1976     Totally extraordinary, but if that's what it takes...
1978     5. PCRE is being used in one environment where neither memmove() nor bcopy() is
1979     available. Added HAVE_BCOPY and an autoconf test for it; if neither
1980     HAVE_MEMMOVE nor HAVE_BCOPY is set, use a built-in emulation function which
1981     assumes the way PCRE uses memmove() (always moving upwards).
1983     6. PCRE is being used in one environment where strchr() is not available. There
1984     was only one use in pcre.c, and writing it out to avoid strchr() probably gives
1985     faster code anyway.
1988 nigel 45 Version 3.1 09-Feb-00
1989     ---------------------
1991     The only change in this release is the fixing of some bugs in Makefile.in for
1992     the "install" target:
1994     (1) It was failing to install pcreposix.h.
1996     (2) It was overwriting the pcre.3 man page with the pcreposix.3 man page.
1999 nigel 43 Version 3.0 01-Feb-00
2000     ---------------------
2001 nigel 41
2002     1. Add support for the /+ modifier to perltest (to output $` like it does in
2003     pcretest).
2005     2. Add support for the /g modifier to perltest.
2007     3. Fix pcretest so that it behaves even more like Perl for /g when the pattern
2008     matches null strings.
2010     4. Fix perltest so that it doesn't do unwanted things when fed an empty
2011     pattern. Perl treats empty patterns specially - it reuses the most recent
2012     pattern, which is not what we want. Replace // by /(?#)/ in order to avoid this
2013     effect.
2015     5. The POSIX interface was broken in that it was just handing over the POSIX
2016     captured string vector to pcre_exec(), but (since release 2.00) PCRE has
2017     required a bigger vector, with some working space on the end. This means that
2018     the POSIX wrapper now has to get and free some memory, and copy the results.
2020 nigel 43 6. Added some simple autoconf support, placing the test data and the
2021     documentation in separate directories, re-organizing some of the
2022     information files, and making it build pcre-config (a GNU standard). Also added
2023     libtool support for building PCRE as a shared library, which is now the
2024     default.
2025 nigel 41
2026 nigel 43 7. Got rid of the leading zero in the definition of PCRE_MINOR because 08 and
2027     09 are not valid octal constants. Single digits will be used for minor values
2028     less than 10.
2030     8. Defined REG_EXTENDED and REG_NOSUB as zero in the POSIX header, so that
2031     existing programs that set these in the POSIX interface can use PCRE without
2032     modification.
2034     9. Added a new function, pcre_fullinfo() with an extensible interface. It can
2035     return all that pcre_info() returns, plus additional data. The pcre_info()
2036     function is retained for compatibility, but is considered to be obsolete.
2038     10. Added experimental recursion feature (?R) to handle one common case that
2039     Perl 5.6 will be able to do with (?p{...}).
2041     11. Added support for POSIX character classes like [:alpha:], which Perl is
2042     adopting.
2045 nigel 39 Version 2.08 31-Aug-99
2046     ----------------------
2048     1. When startoffset was not zero and the pattern began with ".*", PCRE was not
2049     trying to match at the startoffset position, but instead was moving forward to
2050     the next newline as if a previous match had failed.
2052     2. pcretest was not making use of PCRE_NOTEMPTY when repeating for /g and /G,
2053     and could get into a loop if a null string was matched other than at the start
2054     of the subject.
2056     3. Added definitions of PCRE_MAJOR and PCRE_MINOR to pcre.h so the version can
2057     be distinguished at compile time, and for completeness also added PCRE_DATE.
2059     5. Added Paul Sokolovsky's minor changes to make it easy to compile a Win32 DLL
2060     in GnuWin32 environments.
2063 nigel 37 Version 2.07 29-Jul-99
2064     ----------------------
2066     1. The documentation is now supplied in plain text form and HTML as well as in
2067     the form of man page sources.
2069     2. C++ compilers don't like assigning (void *) values to other pointer types.
2070     In particular this affects malloc(). Although there is no problem in Standard
2071     C, I've put in casts to keep C++ compilers happy.
2073     3. Typo on pcretest.c; a cast of (unsigned char *) in the POSIX regexec() call
2074     should be (const char *).
2076     4. If NOPOSIX is defined, pcretest.c compiles without POSIX support. This may
2077     be useful for non-Unix systems who don't want to bother with the POSIX stuff.
2078     However, I haven't made this a standard facility. The documentation doesn't
2079     mention it, and the Makefile doesn't support it.
2081     5. The Makefile now contains an "install" target, with editable destinations at
2082     the top of the file. The pcretest program is not installed.
2084     6. pgrep -V now gives the PCRE version number and date.
2086     7. Fixed bug: a zero repetition after a literal string (e.g. /abcde{0}/) was
2087     causing the entire string to be ignored, instead of just the last character.
2089     8. If a pattern like /"([^\\"]+|\\.)*"/ is applied in the normal way to a
2090     non-matching string, it can take a very, very long time, even for strings of
2091     quite modest length, because of the nested recursion. PCRE now does better in
2092     some of these cases. It does this by remembering the last required literal
2093     character in the pattern, and pre-searching the subject to ensure it is present
2094     before running the real match. In other words, it applies a heuristic to detect
2095     some types of certain failure quickly, and in the above example, if presented
2096     with a string that has no trailing " it gives "no match" very quickly.
2098     9. A new runtime option PCRE_NOTEMPTY causes null string matches to be ignored;
2099     other alternatives are tried instead.
2102 nigel 35 Version 2.06 09-Jun-99
2103     ----------------------
2105     1. Change pcretest's output for amount of store used to show just the code
2106     space, because the remainder (the data block) varies in size between 32-bit and
2107     64-bit systems.
2109     2. Added an extra argument to pcre_exec() to supply an offset in the subject to
2110     start matching at. This allows lookbehinds to work when searching for multiple
2111     occurrences in a string.
2113     3. Added additional options to pcretest for testing multiple occurrences:
2115     /+ outputs the rest of the string that follows a match
2116     /g loops for multiple occurrences, using the new startoffset argument
2117     /G loops for multiple occurrences by passing an incremented pointer
2119     4. PCRE wasn't doing the "first character" optimization for patterns starting
2120     with \b or \B, though it was doing it for other lookbehind assertions. That is,
2121     it wasn't noticing that a match for a pattern such as /\bxyz/ has to start with
2122     the letter 'x'. On long subject strings, this gives a significant speed-up.
2125 nigel 33 Version 2.05 21-Apr-99
2126     ----------------------
2128     1. Changed the type of magic_number from int to long int so that it works
2129     properly on 16-bit systems.
2131     2. Fixed a bug which caused patterns starting with .* not to work correctly
2132     when the subject string contained newline characters. PCRE was assuming
2133     anchoring for such patterns in all cases, which is not correct because .* will
2134     not pass a newline unless PCRE_DOTALL is set. It now assumes anchoring only if
2135     DOTALL is set at top level; otherwise it knows that patterns starting with .*
2136     must be retried after every newline in the subject.
2139 nigel 31 Version 2.04 18-Feb-99
2140     ----------------------
2142     1. For parenthesized subpatterns with repeats whose minimum was zero, the
2143     computation of the store needed to hold the pattern was incorrect (too large).
2144     If such patterns were nested a few deep, this could multiply and become a real
2145     problem.
2147     2. Added /M option to pcretest to show the memory requirement of a specific
2148     pattern. Made -m a synonym of -s (which does this globally) for compatibility.
2150     3. Subpatterns of the form (regex){n,m} (i.e. limited maximum) were being
2151     compiled in such a way that the backtracking after subsequent failure was
2152     pessimal. Something like (a){0,3} was compiled as (a)?(a)?(a)? instead of
2153     ((a)((a)(a)?)?)? with disastrous performance if the maximum was of any size.
2156 nigel 29 Version 2.03 02-Feb-99
2157     ----------------------
2159     1. Fixed typo and small mistake in man page.
2161 nigel 31 2. Added 4th condition (GPL supersedes if conflict) and created separate
2162     LICENCE file containing the conditions.
2163 nigel 29
2164     3. Updated pcretest so that patterns such as /abc\/def/ work like they do in
2165     Perl, that is the internal \ allows the delimiter to be included in the
2166     pattern. Locked out the use of \ as a delimiter. If \ immediately follows
2167     the final delimiter, add \ to the end of the pattern (to test the error).
2169     4. Added the convenience functions for extracting substrings after a successful
2170     match. Updated pcretest to make it able to test these functions.
2173 nigel 27 Version 2.02 14-Jan-99
2174     ----------------------
2176     1. Initialized the working variables associated with each extraction so that
2177     their saving and restoring doesn't refer to uninitialized store.
2179     2. Put dummy code into study.c in order to trick the optimizer of the IBM C
2180     compiler for OS/2 into generating correct code. Apparently IBM isn't going to
2181     fix the problem.
2183     3. Pcretest: the timing code wasn't using LOOPREPEAT for timing execution
2184     calls, and wasn't printing the correct value for compiling calls. Increased the
2185     default value of LOOPREPEAT, and the number of significant figures in the
2186     times.
2188     4. Changed "/bin/rm" in the Makefile to "-rm" so it works on Windows NT.
2190     5. Renamed "deftables" as "dftables" to get it down to 8 characters, to avoid
2191     a building problem on Windows NT with a FAT file system.
2194 nigel 25 Version 2.01 21-Oct-98
2195     ----------------------
2197     1. Changed the API for pcre_compile() to allow for the provision of a pointer
2198     to character tables built by pcre_maketables() in the current locale. If NULL
2199     is passed, the default tables are used.
2202 nigel 23 Version 2.00 24-Sep-98
2203 nigel 21 ----------------------
2205 nigel 23 1. Since the (>?) facility is in Perl 5.005, don't require PCRE_EXTRA to enable
2206     it any more.
2208     2. Allow quantification of (?>) groups, and make it work correctly.
2210     3. The first character computation wasn't working for (?>) groups.
2212     4. Correct the implementation of \Z (it is permitted to match on the \n at the
2213     end of the subject) and add 5.005's \z, which really does match only at the
2214     very end of the subject.
2216     5. Remove the \X "cut" facility; Perl doesn't have it, and (?> is neater.
2218     6. Remove the ability to specify CASELESS, MULTILINE, DOTALL, and
2219     DOLLAR_END_ONLY at runtime, to make it possible to implement the Perl 5.005
2220     localized options. All options to pcre_study() were also removed.
2222     7. Add other new features from 5.005:
2224     $(?<= positive lookbehind
2225     $(?<! negative lookbehind
2226     (?imsx-imsx) added the unsetting capability
2227     such a setting is global if at outer level; local otherwise
2228     (?imsx-imsx:) non-capturing groups with option setting
2229     (?(cond)re|re) conditional pattern matching
2231     A backreference to itself in a repeated group matches the previous
2232     captured string.
2234     8. General tidying up of studying (both automatic and via "study")
2235     consequential on the addition of new assertions.
2237     9. As in 5.005, unlimited repeated groups that could match an empty substring
2238     are no longer faulted at compile time. Instead, the loop is forcibly broken at
2239     runtime if any iteration does actually match an empty substring.
2241     10. Include the RunTest script in the distribution.
2243     11. Added tests from the Perl 5.005_02 distribution. This showed up a few
2244     discrepancies, some of which were old and were also with respect to 5.004. They
2245     have now been fixed.
2248     Version 1.09 28-Apr-98
2249     ----------------------
2251 nigel 21 1. A negated single character class followed by a quantifier with a minimum
2252     value of one (e.g. [^x]{1,6} ) was not compiled correctly. This could lead to
2253     program crashes, or just wrong answers. This did not apply to negated classes
2254     containing more than one character, or to minima other than one.
2257 nigel 19 Version 1.08 27-Mar-98
2258     ----------------------
2260     1. Add PCRE_UNGREEDY to invert the greediness of quantifiers.
2262     2. Add (?U) and (?X) to set PCRE_UNGREEDY and PCRE_EXTRA respectively. The
2263     latter must appear before anything that relies on it in the pattern.
2266 nigel 17 Version 1.07 16-Feb-98
2267     ----------------------
2269     1. A pattern such as /((a)*)*/ was not being diagnosed as in error (unlimited
2270     repeat of a potentially empty string).
2273 nigel 15 Version 1.06 23-Jan-98
2274     ----------------------
2276     1. Added Markus Oberhumer's little patches for C++.
2278     2. Literal strings longer than 255 characters were broken.
2281 nigel 13 Version 1.05 23-Dec-97
2282     ----------------------
2284     1. Negated character classes containing more than one character were failing if
2285     PCRE_CASELESS was set at run time.
2288 nigel 11 Version 1.04 19-Dec-97
2289     ----------------------
2291     1. Corrected the man page, where some "const" qualifiers had been omitted.
2293     2. Made debugging output print "{0,xxx}" instead of just "{,xxx}" to agree with
2294     input syntax.
2296     3. Fixed memory leak which occurred when a regex with back references was
2297     matched with an offsets vector that wasn't big enough. The temporary memory
2298     that is used in this case wasn't being freed if the match failed.
2300     4. Tidied pcretest to ensure it frees memory that it gets.
2302     5. Temporary memory was being obtained in the case where the passed offsets
2303     vector was exactly big enough.
2305     6. Corrected definition of offsetof() from change 5 below.
2307     7. I had screwed up change 6 below and broken the rules for the use of
2308     setjmp(). Now fixed.
2311 nigel 9 Version 1.03 18-Dec-97
2312     ----------------------
2314     1. A erroneous regex with a missing opening parenthesis was correctly
2315     diagnosed, but PCRE attempted to access brastack[-1], which could cause crashes
2316     on some systems.
2318     2. Replaced offsetof(real_pcre, code) by offsetof(real_pcre, code[0]) because
2319     it was reported that one broken compiler failed on the former because "code" is
2320     also an independent variable.
2322     3. The erroneous regex a[]b caused an array overrun reference.
2324     4. A regex ending with a one-character negative class (e.g. /[^k]$/) did not
2325     fail on data ending with that character. (It was going on too far, and checking
2326     the next character, typically a binary zero.) This was specific to the
2327     optimized code for single-character negative classes.
2329     5. Added a contributed patch from the TIN world which does the following:
2331     + Add an undef for memmove, in case the the system defines a macro for it.
2333     + Add a definition of offsetof(), in case there isn't one. (I don't know
2334     the reason behind this - offsetof() is part of the ANSI standard - but
2335     it does no harm).
2337     + Reduce the ifdef's in pcre.c using macro DPRINTF, thereby eliminating
2338     most of the places where whitespace preceded '#'. I have given up and
2339     allowed the remaining 2 cases to be at the margin.
2341     + Rename some variables in pcre to eliminate shadowing. This seems very
2342     pedantic, but does no harm, of course.
2344     6. Moved the call to setjmp() into its own function, to get rid of warnings
2345     from gcc -Wall, and avoided calling it at all unless PCRE_EXTRA is used.
2347     7. Constructs such as \d{8,} were compiling into the equivalent of
2348 nigel 11 \d{8}\d{0,65527} instead of \d{8}\d* which didn't make much difference to the
2349 nigel 9 outcome, but in this particular case used more store than had been allocated,
2350     which caused the bug to be discovered because it threw up an internal error.
2352     8. The debugging code in both pcre and pcretest for outputting the compiled
2353     form of a regex was going wrong in the case of back references followed by
2354     curly-bracketed repeats.
2357 nigel 7 Version 1.02 12-Dec-97
2358     ----------------------
2360     1. Typos in pcre.3 and comments in the source fixed.
2362     2. Applied a contributed patch to get rid of places where it used to remove
2363     'const' from variables, and fixed some signed/unsigned and uninitialized
2364     variable warnings.
2366     3. Added the "runtest" target to Makefile.
2368     4. Set default compiler flag to -O2 rather than just -O.
2371 nigel 5 Version 1.01 19-Nov-97
2372     ----------------------
2374     1. PCRE was failing to diagnose unlimited repeat of empty string for patterns
2375     like /([ab]*)*/, that is, for classes with more than one character in them.
2377     2. Likewise, it wasn't diagnosing patterns with "once-only" subpatterns, such
2378     as /((?>a*))*/ (a PCRE_EXTRA facility).
2381     Version 1.00 18-Nov-97
2382     ----------------------
2384     1. Added compile-time macros to support systems such as SunOS4 which don't have
2385     memmove() or strerror() but have other things that can be used instead.
2387     2. Arranged that "make clean" removes the executables.
2390 nigel 3 Version 0.99 27-Oct-97
2391     ----------------------
2393     1. Fixed bug in code for optimizing classes with only one character. It was
2394     initializing a 32-byte map regardless, which could cause it to run off the end
2395     of the memory it had got.
2397     2. Added, conditional on PCRE_EXTRA, the proposed (?>REGEX) construction.
2400     Version 0.98 22-Oct-97
2401     ----------------------
2403     1. Fixed bug in code for handling temporary memory usage when there are more
2404     back references than supplied space in the ovector. This could cause segfaults.
2407     Version 0.97 21-Oct-97
2408     ----------------------
2410     1. Added the \X "cut" facility, conditional on PCRE_EXTRA.
2412     2. Optimized negated single characters not to use a bit map.
2414     3. Brought error texts together as macro definitions; clarified some of them;
2415     fixed one that was wrong - it said "range out of order" when it meant "invalid
2416     escape sequence".
2418     4. Changed some char * arguments to const char *.
2420     5. Added PCRE_NOTBOL and PCRE_NOTEOL (from POSIX).
2422     6. Added the POSIX-style API wrapper in pcreposix.a and testing facilities in
2423     pcretest.
2426     Version 0.96 16-Oct-97
2427     ----------------------
2429     1. Added a simple "pgrep" utility to the distribution.
2431     2. Fixed an incompatibility with Perl: "{" is now treated as a normal character
2432     unless it appears in one of the precise forms "{ddd}", "{ddd,}", or "{ddd,ddd}"
2433     where "ddd" means "one or more decimal digits".
2435     3. Fixed serious bug. If a pattern had a back reference, but the call to
2436     pcre_exec() didn't supply a large enough ovector to record the related
2437     identifying subpattern, the match always failed. PCRE now remembers the number
2438     of the largest back reference, and gets some temporary memory in which to save
2439     the offsets during matching if necessary, in order to ensure that
2440     backreferences always work.
2442     4. Increased the compatibility with Perl in a number of ways:
2444     (a) . no longer matches \n by default; an option PCRE_DOTALL is provided
2445     to request this handling. The option can be set at compile or exec time.
2447     (b) $ matches before a terminating newline by default; an option
2448     PCRE_DOLLAR_ENDONLY is provided to override this (but not in multiline
2449     mode). The option can be set at compile or exec time.
2451     (c) The handling of \ followed by a digit other than 0 is now supposed to be
2452     the same as Perl's. If the decimal number it represents is less than 10
2453     or there aren't that many previous left capturing parentheses, an octal
2454     escape is read. Inside a character class, it's always an octal escape,
2455     even if it is a single digit.
2457     (d) An escaped but undefined alphabetic character is taken as a literal,
2458     unless PCRE_EXTRA is set. Currently this just reserves the remaining
2459     escapes.
2461     (e) {0} is now permitted. (The previous item is removed from the compiled
2462     pattern).
2464     5. Changed all the names of code files so that the basic parts are no longer
2465     than 10 characters, and abolished the teeny "globals.c" file.
2467     6. Changed the handling of character classes; they are now done with a 32-byte
2468     bit map always.
2470     7. Added the -d and /D options to pcretest to make it possible to look at the
2471     internals of compilation without having to recompile pcre.
2474     Version 0.95 23-Sep-97
2475     ----------------------
2477     1. Fixed bug in pre-pass concerning escaped "normal" characters such as \x5c or
2478     \x20 at the start of a run of normal characters. These were being treated as
2479     real characters, instead of the source characters being re-checked.
2482     Version 0.94 18-Sep-97
2483     ----------------------
2485     1. The functions are now thread-safe, with the caveat that the global variables
2486     containing pointers to malloc() and free() or alternative functions are the
2487     same for all threads.
2489     2. Get pcre_study() to generate a bitmap of initial characters for non-
2490     anchored patterns when this is possible, and use it if passed to pcre_exec().
2493     Version 0.93 15-Sep-97
2494     ----------------------
2496     1. /(b)|(:+)/ was computing an incorrect first character.
2498     2. Add pcre_study() to the API and the passing of pcre_extra to pcre_exec(),
2499     but not actually doing anything yet.
2501     3. Treat "-" characters in classes that cannot be part of ranges as literals,
2502     as Perl does (e.g. [-az] or [az-]).
2504     4. Set the anchored flag if a branch starts with .* or .*? because that tests
2505     all possible positions.
2507     5. Split up into different modules to avoid including unneeded functions in a
2508     compiled binary. However, compile and exec are still in one module. The "study"
2509     function is split off.
2511     6. The character tables are now in a separate module whose source is generated
2512     by an auxiliary program - but can then be edited by hand if required. There are
2513     now no calls to isalnum(), isspace(), isdigit(), isxdigit(), tolower() or
2514     toupper() in the code.
2516     7. Turn the malloc/free funtions variables into pcre_malloc and pcre_free and
2517     make them global. Abolish the function for setting them, as the caller can now
2518     set them directly.
2521     Version 0.92 11-Sep-97
2522     ----------------------
2524     1. A repeat with a fixed maximum and a minimum of 1 for an ordinary character
2525     (e.g. /a{1,3}/) was broken (I mis-optimized it).
2527     2. Caseless matching was not working in character classes if the characters in
2528     the pattern were in upper case.
2530     3. Make ranges like [W-c] work in the same way as Perl for caseless matching.
2532     4. Make PCRE_ANCHORED public and accept as a compile option.
2534     5. Add an options word to pcre_exec() and accept PCRE_ANCHORED and
2535     PCRE_CASELESS at run time. Add escapes \A and \I to pcretest to cause it to
2536     pass them.
2538     6. Give an error if bad option bits passed at compile or run time.
2540     7. Add PCRE_MULTILINE at compile and exec time, and (?m) as well. Add \M to
2541     pcretest to cause it to pass that flag.
2543     8. Add pcre_info(), to get the number of identifying subpatterns, the stored
2544     options, and the first character, if set.
2546     9. Recognize C+ or C{n,m} where n >= 1 as providing a fixed starting character.
2549     Version 0.91 10-Sep-97
2550     ----------------------
2552     1. PCRE was failing to diagnose unlimited repeats of subpatterns that could
2553     match the empty string as in /(a*)*/. It was looping and ultimately crashing.
2555     2. PCRE was looping on encountering an indefinitely repeated back reference to
2556     a subpattern that had matched an empty string, e.g. /(a|)\1*/. It now does what
2557     Perl does - treats the match as successful.
2559     ****


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