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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
3    
4    Version 7.1 05-Mar-07
5    ---------------------
6    
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. There
9        is some re-arrangement of the files and adjustment of comments consequent
10        on this.
11    
12     2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
13        for recursive directory scanning broke on some systems because the files
14        are not scanned in any specific order and on different systems the order
15        was different. A call to "sort" has been inserted into RunGrepTest for the
16        approprate test as a short-term fix. In the longer term there may be an
17        alternative.
18    
19     3. I had an email from Eric Raymond about problems translating some of PCRE's
20        man pages to HTML (despite the fact that I distribute HTML pages, some
21        people do their own conversions for various reasons). The problems
22        concerned the use of low-level troff macros .br and .in. I have therefore
23        removed all such uses from the man pages (some were redundant, some could
24        be replaced by .nf/.fi pairs). The 132html script that I use to generate
25        HTML has been updated to handle .nf/.fi and to complain if it encounters
26        .br or .in.
27    
28     4. Updated comments in configure.ac that get placed in config.h.in and also
29        arranged for config.h to be included in the distribution, with the name
30        config.h.generic, for the benefit of those who have to compile without
31        Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
32    
33     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
34        Weber: (1) pcre_internal.h was missing some function renames; (2) updated
35        makevp.bat for the current PCRE, using the additional files !compile.txt,
36        !linklib.txt, and pcregexp.pas.
37    
38     6. A Windows user reported a minor discrepancy with test 2, which turned out
39        to be caused by a trailing space on an input line that had got lost in his
40        copy. The trailing space was an accident, so I've just removed it.
41    
42     7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
43        that is needed.
44    
45     8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
46        as "const" (a) because they are and (b) because it helps the PHP
47        maintainers who have recently made a script to detect big data structures
48        in the php code that should be moved to the .rodata section. I remembered
49        to update Builducptable as well, so it won't revert if ucptable.h is ever
50        re-created.
51    
52     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
53        pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
54        order to be able to cut out the UTF-8 tables in the latter when UTF-8
55        support is not required. This saves 1.5-2K of code, which is important in
56        some applications.
57    
58        Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
59        so as not to refer to the tables, even though these functions will never be
60        called when UTF-8 support is disabled. Otherwise there are problems with a
61        shared library.
62    
63    10. The emulated memmove() function in pcre_internal.h (provided for those
64        environments that have neither memmove() nor bcopy()) was defining its
65        arguments as char * instead of void *.
66    
67    11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
68        and Detrail to create the HTML documentation, the .txt form of the man
69        pages, and it removes trailing spaces from listed files. It also creates
70        pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
71        case, it wraps all the #defines with #ifndefs. This script should be run
72        before "make dist".
73    
74    
75    Version 7.0 19-Dec-06
76    ---------------------
77    
78     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
79        moving to gcc 4.1.1.
80    
81     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
82        sys/time.h, which is documented as needed for this function. It doesn't
83        seem to matter on Linux, but it showed up on some releases of OS X.
84    
85     3. It seems that there are systems where bytes whose values are greater than
86        127 match isprint() in the "C" locale. The "C" locale should be the
87        default when a C program starts up. In most systems, only ASCII printing
88        characters match isprint(). This difference caused the output from pcretest
89        to vary, making some of the tests fail. I have changed pcretest so that:
90    
91        (a) When it is outputting text in the compiled version of a pattern, bytes
92            other than 32-126 are always shown as hex escapes.
93    
94        (b) When it is outputting text that is a matched part of a subject string,
95            it does the same, unless a different locale has been set for the match
96            (using the /L modifier). In this case, it uses isprint() to decide.
97    
98     4. Fixed a major bug that caused incorrect computation of the amount of memory
99        required for a compiled pattern when options that changed within the
100        pattern affected the logic of the preliminary scan that determines the
101        length. The relevant options are -x, and -i in UTF-8 mode. The result was
102        that the computed length was too small. The symptoms of this bug were
103        either the PCRE error "internal error: code overflow" from pcre_compile(),
104        or a glibc crash with a message such as "pcretest: free(): invalid next
105        size (fast)". Examples of patterns that provoked this bug (shown in
106        pcretest format) are:
107    
108          /(?-x: )/x
109          /(?x)(?-x: \s*#\s*)/
110          /((?i)[\x{c0}])/8
111          /(?i:[\x{c0}])/8
112    
113        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
114        is now done differently.
115    
116     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
117        wrapper classes; (b) implement a new function in the C++ scanner that is
118        more efficient than the old way of doing things because it avoids levels of
119        recursion in the regex matching; (c) add a paragraph to the documentation
120        for the FullMatch() function.
121    
122     6. The escape sequence \n was being treated as whatever was defined as
123        "newline". Not only was this contrary to the documentation, which states
124        that \n is character 10 (hex 0A), but it also went horribly wrong when
125        "newline" was defined as CRLF. This has been fixed.
126    
127     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
128        was being set to -1 for the "end of line" case (supposedly a value that no
129        character can have). Though this value is never used (the check for end of
130        line is "zero bytes in current character"), it caused compiler complaints.
131        I've changed it to 0xffffffff.
132    
133     8. In pcre_version.c, the version string was being built by a sequence of
134        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
135        string (as it is for production releases) called a macro with an empty
136        argument. The C standard says the result of this is undefined. The gcc
137        compiler treats it as an empty string (which was what was wanted) but it is
138        reported that Visual C gives an error. The source has been hacked around to
139        avoid this problem.
140    
141     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
142        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
143        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
144        of them did).
145    
146    10. Originally, pcretest opened its input and output without "b"; then I was
147        told that "b" was needed in some environments, so it was added for release
148        5.0 to both the input and output. (It makes no difference on Unix-like
149        systems.) Later I was told that it is wrong for the input on Windows. I've
150        now abstracted the modes into two macros, to make it easier to fiddle with
151        them, and removed "b" from the input mode under Windows.
152    
153    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
154    
155    12. Added -help and --help to pcretest as an official way of being reminded
156        of the options.
157    
158    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
159        and pcrecpp.cc because they annoy compilers at high warning levels.
160    
161    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
162    
163    15. Fixed an occurrence of == in configure.ac that should have been = (shell
164        scripts are not C programs :-) and which was not noticed because it works
165        on Linux.
166    
167    16. pcretest is supposed to handle any length of pattern and data line (as one
168        line or as a continued sequence of lines) by extending its input buffer if
169        necessary. This feature was broken for very long pattern lines, leading to
170        a string of junk being passed to pcre_compile() if the pattern was longer
171        than about 50K.
172    
173    17. I have done a major re-factoring of the way pcre_compile() computes the
174        amount of memory needed for a compiled pattern. Previously, there was code
175        that made a preliminary scan of the pattern in order to do this. That was
176        OK when PCRE was new, but as the facilities have expanded, it has become
177        harder and harder to keep it in step with the real compile phase, and there
178        have been a number of bugs (see for example, 4 above). I have now found a
179        cunning way of running the real compile function in a "fake" mode that
180        enables it to compute how much memory it would need, while actually only
181        ever using a few hundred bytes of working memory and without too many
182        tests of the mode. This should make future maintenance and development
183        easier. A side effect of this work is that the limit of 200 on the nesting
184        depth of parentheses has been removed (though this was never a serious
185        limitation, I suspect). However, there is a downside: pcre_compile() now
186        runs more slowly than before (30% or more, depending on the pattern). I
187        hope this isn't a big issue. There is no effect on runtime performance.
188    
189    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
190        newline (only possible for the last line of a file) and it was a
191        pattern that set a locale (followed by /Lsomething), pcretest crashed.
192    
193    19. Added additional timing features to pcretest. (1) The -tm option now times
194        matching only, not compiling. (2) Both -t and -tm can be followed, as a
195        separate command line item, by a number that specifies the number of
196        repeats to use when timing. The default is 50000; this gives better
197        precision, but takes uncomfortably long for very large patterns.
198    
199    20. Extended pcre_study() to be more clever in cases where a branch of a
200        subpattern has no definite first character. For example, (a*|b*)[cd] would
201        previously give no result from pcre_study(). Now it recognizes that the
202        first character must be a, b, c, or d.
203    
204    21. There was an incorrect error "recursive call could loop indefinitely" if
205        a subpattern (or the entire pattern) that was being tested for matching an
206        empty string contained only one non-empty item after a nested subpattern.
207        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
208        incorrectly, because the \d was being skipped in the check.
209    
210    22. The pcretest program now has a new pattern option /B and a command line
211        option -b, which is equivalent to adding /B to every pattern. This causes
212        it to show the compiled bytecode, without the additional information that
213        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
214        is the same as /B/I).
215    
216    23. A new optimization is now able automatically to treat some sequences such
217        as a*b as a*+b. More specifically, if something simple (such as a character
218        or a simple class like \d) has an unlimited quantifier, and is followed by
219        something that cannot possibly match the quantified thing, the quantifier
220        is automatically "possessified".
221    
222    24. A recursive reference to a subpattern whose number was greater than 39
223        went wrong under certain circumstances in UTF-8 mode. This bug could also
224        have affected the operation of pcre_study().
225    
226    25. Realized that a little bit of performance could be had by replacing
227        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
228    
229    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
230    
231    27. Possessive quantifiers such as a++ were previously implemented by turning
232        them into atomic groups such as ($>a+). Now they have their own opcodes,
233        which improves performance. This includes the automatically created ones
234        from 23 above.
235    
236    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
237        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
238        the first matched character to be a colon. This applied both to named and
239        numbered groups.
240    
241    29. The ucpinternal.h header file was missing its idempotency #ifdef.
242    
243    30. I was sent a "project" file called libpcre.a.dev which I understand makes
244        building PCRE on Windows easier, so I have included it in the distribution.
245    
246    31. There is now a check in pcretest against a ridiculously large number being
247        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
248        loop, the loop is abandoned.
249    
250    32. Forward references to subpatterns in conditions such as (?(2)...) where
251        subpattern 2 is defined later cause pcre_compile() to search forwards in
252        the pattern for the relevant set of parentheses. This search went wrong
253        when there were unescaped parentheses in a character class, parentheses
254        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
255    
256    33. "Subroutine" calls and backreferences were previously restricted to
257        referencing subpatterns earlier in the regex. This restriction has now
258        been removed.
259    
260    34. Added a number of extra features that are going to be in Perl 5.10. On the
261        whole, these are just syntactic alternatives for features that PCRE had
262        previously implemented using the Python syntax or my own invention. The
263        other formats are all retained for compatibility.
264    
265        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
266            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
267            also .NET compatible.
268    
269        (b) A recursion or subroutine call to a named group can now be defined as
270            (?&name) as well as (?P>name).
271    
272        (c) A backreference to a named group can now be defined as \k<name> or
273            \k'name' as well as (?P=name). The new forms, as well as being in Perl
274            5.10, are also .NET compatible.
275    
276        (d) A conditional reference to a named group can now use the syntax
277            (?(<name>) or (?('name') as well as (?(name).
278    
279        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
280            groups (named and numbered) that are never evaluated inline, but can be
281            called as "subroutines" from elsewhere. In effect, the DEFINE condition
282            is always false. There may be only one alternative in such a group.
283    
284        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
285            as the simple (?(R). The condition is true only if the most recent
286            recursion is that of the given number or name. It does not search out
287            through the entire recursion stack.
288    
289        (g) The escape \gN or \g{N} has been added, where N is a positive or
290            negative number, specifying an absolute or relative reference.
291    
292    35. Tidied to get rid of some further signed/unsigned compiler warnings and
293        some "unreachable code" warnings.
294    
295    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
296        things, this adds five new scripts.
297    
298    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
299        There were also incompatibilities regarding the handling of \Q..\E inside
300        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
301        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
302    
303    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
304        matches an empty string, and forcibly breaks the loop. There were bugs in
305        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
306        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
307        separate and independent bugs (that affected different cases) have been
308        fixed.
309    
310    39. Refactored the code to abolish the use of different opcodes for small
311        capturing bracket numbers. This is a tidy that I avoided doing when I
312        removed the limit on the number of capturing brackets for 3.5 back in 2001.
313        The new approach is not only tidier, it makes it possible to reduce the
314        memory needed to fix the previous bug (38).
315    
316    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
317        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
318        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
319        mode.
320    
321    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
322        report.
323    
324    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
325        copy construction and assignment in the C++ wrapper.
326    
327    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
328        couple of bugs that could have given wrong results in the "--newline=crlf"
329        case.
330    
331    44. Added a number of casts and did some reorganization of signed/unsigned int
332        variables following suggestions from Dair Grant. Also renamed the variable
333        "this" as "item" because it is a C++ keyword.
334    
335    45. Arranged for dftables to add
336    
337          #include "pcre_internal.h"
338    
339        to pcre_chartables.c because without it, gcc 4.x may remove the array
340        definition from the final binary if PCRE is built into a static library and
341        dead code stripping is activated.
342    
343    46. For an unanchored pattern, if a match attempt fails at the start of a
344        newline sequence, and the newline setting is CRLF or ANY, and the next two
345        characters are CRLF, advance by two characters instead of one.
346    
347    
348    Version 6.7 04-Jul-06
349    ---------------------
350    
351     1. In order to handle tests when input lines are enormously long, pcretest has
352        been re-factored so that it automatically extends its buffers when
353        necessary. The code is crude, but this _is_ just a test program. The
354        default size has been increased from 32K to 50K.
355    
356     2. The code in pcre_study() was using the value of the re argument before
357        testing it for NULL. (Of course, in any sensible call of the function, it
358        won't be NULL.)
359    
360     3. The memmove() emulation function in pcre_internal.h, which is used on
361        systems that lack both memmove() and bcopy() - that is, hardly ever -
362        was missing a "static" storage class specifier.
363    
364     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
365        containing an extended class (one that cannot be represented by a bitmap
366        because it contains high-valued characters or Unicode property items, e.g.
367        [\pZ]). Almost always one would set UTF-8 mode when processing such a
368        pattern, but PCRE should not loop if you do not (it no longer does).
369        [Detail: two cases were found: (a) a repeated subpattern containing an
370        extended class; (b) a recursive reference to a subpattern that followed a
371        previous extended class. It wasn't skipping over the extended class
372        correctly when UTF-8 mode was not set.]
373    
374     5. A negated single-character class was not being recognized as fixed-length
375        in lookbehind assertions such as (?<=[^f]), leading to an incorrect
376        compile error "lookbehind assertion is not fixed length".
377    
378     6. The RunPerlTest auxiliary script was showing an unexpected difference
379        between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
380        write a Perl script that can interpret lines of an input file either as
381        byte characters or as UTF-8, which is what "perltest" was being required to
382        do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
383        can't do is switch easily at run time between having the "use utf8;" pragma
384        or not. In the end, I fudged it by using the RunPerlTest script to insert
385        "use utf8;" explicitly for the UTF-8 tests.
386    
387     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
388        the end of the subject string, contrary to the documentation and to what
389        Perl does. This was true of both matching functions. Now it matches only at
390        the start of the subject and immediately after *internal* newlines.
391    
392     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
393        a pointer to an int instead of a pointer to an unsigned long int. This
394        caused problems on 64-bit systems.
395    
396     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
397        instance of the 'standard' template library not being so standard".
398    
399    10. There was no check on the number of named subpatterns nor the maximum
400        length of a subpattern name. The product of these values is used to compute
401        the size of the memory block for a compiled pattern. By supplying a very
402        long subpattern name and a large number of named subpatterns, the size
403        computation could be caused to overflow. This is now prevented by limiting
404        the length of names to 32 characters, and the number of named subpatterns
405        to 10,000.
406    
407    11. Subpatterns that are repeated with specific counts have to be replicated in
408        the compiled pattern. The size of memory for this was computed from the
409        length of the subpattern and the repeat count. The latter is limited to
410        65535, but there was no limit on the former, meaning that integer overflow
411        could in principle occur. The compiled length of a repeated subpattern is
412        now limited to 30,000 bytes in order to prevent this.
413    
414    12. Added the optional facility to have named substrings with the same name.
415    
416    13. Added the ability to use a named substring as a condition, using the
417        Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
418        are numbers (not recommended). Forward references are permitted.
419    
420    14. Added forward references in named backreferences (if you see what I mean).
421    
422    15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
423        pattern could run off the end of the subject. For example, the pattern
424        "(?s)(.{1,5})"8 did this with the subject "ab".
425    
426    16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
427        PCRE_CASELESS was set when matching characters that were quantified with ?
428        or *.
429    
430    17. A character class other than a single negated character that had a minimum
431        but no maximum quantifier - for example [ab]{6,} - was not handled
432        correctly by pce_dfa_exec(). It would match only one character.
433    
434    18. A valid (though odd) pattern that looked like a POSIX character
435        class but used an invalid character after [ (for example [[,abc,]]) caused
436        pcre_compile() to give the error "Failed: internal error: code overflow" or
437        in some cases to crash with a glibc free() error. This could even happen if
438        the pattern terminated after [[ but there just happened to be a sequence of
439        letters, a binary zero, and a closing ] in the memory that followed.
440    
441    19. Perl's treatment of octal escapes in the range \400 to \777 has changed
442        over the years. Originally (before any Unicode support), just the bottom 8
443        bits were taken. Thus, for example, \500 really meant \100. Nowadays the
444        output from "man perlunicode" includes this:
445    
446          The regular expression compiler produces polymorphic opcodes.  That
447          is, the pattern adapts to the data and automatically switches to
448          the Unicode character scheme when presented with Unicode data--or
449          instead uses a traditional byte scheme when presented with byte
450          data.
451    
452        Sadly, a wide octal escape does not cause a switch, and in a string with
453        no other multibyte characters, these octal escapes are treated as before.
454        Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
455        /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
456        Unicode string.
457    
458        I have not perpetrated such confusion in PCRE. Up till now, it took just
459        the bottom 8 bits, as in old Perl. I have now made octal escapes with
460        values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
461        translate to the appropriate multibyte character.
462    
463    29. Applied some refactoring to reduce the number of warnings from Microsoft
464        and Borland compilers. This has included removing the fudge introduced
465        seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
466        a warning about an unused variable.
467    
468    21. PCRE has not included VT (character 0x0b) in the set of whitespace
469        characters since release 4.0, because Perl (from release 5.004) does not.
470        [Or at least, is documented not to: some releases seem to be in conflict
471        with the documentation.] However, when a pattern was studied with
472        pcre_study() and all its branches started with \s, PCRE still included VT
473        as a possible starting character. Of course, this did no harm; it just
474        caused an unnecessary match attempt.
475    
476    22. Removed a now-redundant internal flag bit that recorded the fact that case
477        dependency changed within the pattern. This was once needed for "required
478        byte" processing, but is no longer used. This recovers a now-scarce options
479        bit. Also moved the least significant internal flag bit to the most-
480        significant bit of the word, which was not previously used (hangover from
481        the days when it was an int rather than a uint) to free up another bit for
482        the future.
483    
484    23. Added support for CRLF line endings as well as CR and LF. As well as the
485        default being selectable at build time, it can now be changed at runtime
486        via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
487        specify that it is scanning data with non-default line endings.
488    
489    24. Changed the definition of CXXLINK to make it agree with the definition of
490        LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
491    
492    25. Applied Ian Taylor's patches to avoid using another stack frame for tail
493        recursions. This makes a big different to stack usage for some patterns.
494    
495    26. If a subpattern containing a named recursion or subroutine reference such
496        as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
497        the space required for the compiled pattern went wrong and gave too small a
498        value. Depending on the environment, this could lead to "Failed: internal
499        error: code overflow at offset 49" or "glibc detected double free or
500        corruption" errors.
501    
502    27. Applied patches from Google (a) to support the new newline modes and (b) to
503        advance over multibyte UTF-8 characters in GlobalReplace.
504    
505    28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
506        difference for some implementation of PCRE in some Windows version.
507    
508    29. Added some extra testing facilities to pcretest:
509    
510        \q<number>   in a data line sets the "match limit" value
511        \Q<number>   in a data line sets the "match recursion limt" value
512        -S <number>  sets the stack size, where <number> is in megabytes
513    
514        The -S option isn't available for Windows.
515    
516    
517    Version 6.6 06-Feb-06
518    ---------------------
519    
520     1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
521        in pcreposix.h. I have copied the definition from pcre.h.
522    
523     2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
524        because pcre.h is no longer a built file.
525    
526     3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
527        not normally included in the compiled code.
528    
529    
530    Version 6.5 01-Feb-06
531    ---------------------
532    
533     1. When using the partial match feature with pcre_dfa_exec(), it was not
534        anchoring the second and subsequent partial matches at the new starting
535        point. This could lead to incorrect results. For example, with the pattern
536        /1234/, partially matching against "123" and then "a4" gave a match.
537    
538     2. Changes to pcregrep:
539    
540        (a) All non-match returns from pcre_exec() were being treated as failures
541            to match the line. Now, unless the error is PCRE_ERROR_NOMATCH, an
542            error message is output. Some extra information is given for the
543            PCRE_ERROR_MATCHLIMIT and PCRE_ERROR_RECURSIONLIMIT errors, which are
544            probably the only errors that are likely to be caused by users (by
545            specifying a regex that has nested indefinite repeats, for instance).
546            If there are more than 20 of these errors, pcregrep is abandoned.
547    
548        (b) A binary zero was treated as data while matching, but terminated the
549            output line if it was written out. This has been fixed: binary zeroes
550            are now no different to any other data bytes.
551    
552        (c) Whichever of the LC_ALL or LC_CTYPE environment variables is set is
553            used to set a locale for matching. The --locale=xxxx long option has
554            been added (no short equivalent) to specify a locale explicitly on the
555            pcregrep command, overriding the environment variables.
556    
557        (d) When -B was used with -n, some line numbers in the output were one less
558            than they should have been.
559    
560        (e) Added the -o (--only-matching) option.
561    
562        (f) If -A or -C was used with -c (count only), some lines of context were
563            accidentally printed for the final match.
564    
565        (g) Added the -H (--with-filename) option.
566    
567        (h) The combination of options -rh failed to suppress file names for files
568            that were found from directory arguments.
569    
570        (i) Added the -D (--devices) and -d (--directories) options.
571    
572        (j) Added the -F (--fixed-strings) option.
573    
574        (k) Allow "-" to be used as a file name for -f as well as for a data file.
575    
576        (l) Added the --colo(u)r option.
577    
578        (m) Added Jeffrey Friedl's -S testing option, but within #ifdefs so that it
579            is not present by default.
580    
581     3. A nasty bug was discovered in the handling of recursive patterns, that is,
582        items such as (?R) or (?1), when the recursion could match a number of
583        alternatives. If it matched one of the alternatives, but subsequently,
584        outside the recursion, there was a failure, the code tried to back up into
585        the recursion. However, because of the way PCRE is implemented, this is not
586        possible, and the result was an incorrect result from the match.
587    
588        In order to prevent this happening, the specification of recursion has
589        been changed so that all such subpatterns are automatically treated as
590        atomic groups. Thus, for example, (?R) is treated as if it were (?>(?R)).
591    
592     4. I had overlooked the fact that, in some locales, there are characters for
593        which isalpha() is true but neither isupper() nor islower() are true. In
594        the fr_FR locale, for instance, the \xAA and \xBA characters (ordmasculine
595        and ordfeminine) are like this. This affected the treatment of \w and \W
596        when they appeared in character classes, but not when they appeared outside
597        a character class. The bit map for "word" characters is now created
598        separately from the results of isalnum() instead of just taking it from the
599        upper, lower, and digit maps. (Plus the underscore character, of course.)
600    
601     5. The above bug also affected the handling of POSIX character classes such as
602        [[:alpha:]] and [[:alnum:]]. These do not have their own bit maps in PCRE's
603        permanent tables. Instead, the bit maps for such a class were previously
604        created as the appropriate unions of the upper, lower, and digit bitmaps.
605        Now they are created by subtraction from the [[:word:]] class, which has
606        its own bitmap.
607    
608     6. The [[:blank:]] character class matches horizontal, but not vertical space.
609        It is created by subtracting the vertical space characters (\x09, \x0a,
610        \x0b, \x0c) from the [[:space:]] bitmap. Previously, however, the
611        subtraction was done in the overall bitmap for a character class, meaning
612        that a class such as [\x0c[:blank:]] was incorrect because \x0c would not
613        be recognized. This bug has been fixed.
614    
615     7. Patches from the folks at Google:
616    
617          (a) pcrecpp.cc: "to handle a corner case that may or may not happen in
618          real life, but is still worth protecting against".
619    
620          (b) pcrecpp.cc: "corrects a bug when negative radixes are used with
621          regular expressions".
622    
623          (c) pcre_scanner.cc: avoid use of std::count() because not all systems
624          have it.
625    
626          (d) Split off pcrecpparg.h from pcrecpp.h and had the former built by
627          "configure" and the latter not, in order to fix a problem somebody had
628          with compiling the Arg class on HP-UX.
629    
630          (e) Improve the error-handling of the C++ wrapper a little bit.
631    
632          (f) New tests for checking recursion limiting.
633    
634     8. The pcre_memmove() function, which is used only if the environment does not
635        have a standard memmove() function (and is therefore rarely compiled),
636        contained two bugs: (a) use of int instead of size_t, and (b) it was not
637        returning a result (though PCRE never actually uses the result).
638    
639     9. In the POSIX regexec() interface, if nmatch is specified as a ridiculously
640        large number - greater than INT_MAX/(3*sizeof(int)) - REG_ESPACE is
641        returned instead of calling malloc() with an overflowing number that would
642        most likely cause subsequent chaos.
643    
644    10. The debugging option of pcretest was not showing the NO_AUTO_CAPTURE flag.
645    
646    11. The POSIX flag REG_NOSUB is now supported. When a pattern that was compiled
647        with this option is matched, the nmatch and pmatch options of regexec() are
648        ignored.
649    
650    12. Added REG_UTF8 to the POSIX interface. This is not defined by POSIX, but is
651        provided in case anyone wants to the the POSIX interface with UTF-8
652        strings.
653    
654    13. Added CXXLDFLAGS to the Makefile parameters to provide settings only on the
655        C++ linking (needed for some HP-UX environments).
656    
657    14. Avoid compiler warnings in get_ucpname() when compiled without UCP support
658        (unused parameter) and in the pcre_printint() function (omitted "default"
659        switch label when the default is to do nothing).
660    
661    15. Added some code to make it possible, when PCRE is compiled as a C++
662        library, to replace subject pointers for pcre_exec() with a smart pointer
663        class, thus making it possible to process discontinuous strings.
664    
665    16. The two macros PCRE_EXPORT and PCRE_DATA_SCOPE are confusing, and perform
666        much the same function. They were added by different people who were trying
667        to make PCRE easy to compile on non-Unix systems. It has been suggested
668        that PCRE_EXPORT be abolished now that there is more automatic apparatus
669        for compiling on Windows systems. I have therefore replaced it with
670        PCRE_DATA_SCOPE. This is set automatically for Windows; if not set it
671        defaults to "extern" for C or "extern C" for C++, which works fine on
672        Unix-like systems. It is now possible to override the value of PCRE_DATA_
673        SCOPE with something explicit in config.h. In addition:
674    
675        (a) pcreposix.h still had just "extern" instead of either of these macros;
676            I have replaced it with PCRE_DATA_SCOPE.
677    
678        (b) Functions such as _pcre_xclass(), which are internal to the library,
679            but external in the C sense, all had PCRE_EXPORT in their definitions.
680            This is apparently wrong for the Windows case, so I have removed it.
681            (It makes no difference on Unix-like systems.)
682    
683    17. Added a new limit, MATCH_LIMIT_RECURSION, which limits the depth of nesting
684        of recursive calls to match(). This is different to MATCH_LIMIT because
685        that limits the total number of calls to match(), not all of which increase
686        the depth of recursion. Limiting the recursion depth limits the amount of
687        stack (or heap if NO_RECURSE is set) that is used. The default can be set
688        when PCRE is compiled, and changed at run time. A patch from Google adds
689        this functionality to the C++ interface.
690    
691    18. Changes to the handling of Unicode character properties:
692    
693        (a) Updated the table to Unicode 4.1.0.
694    
695        (b) Recognize characters that are not in the table as "Cn" (undefined).
696    
697        (c) I revised the way the table is implemented to a much improved format
698            which includes recognition of ranges. It now supports the ranges that
699            are defined in UnicodeData.txt, and it also amalgamates other
700            characters into ranges. This has reduced the number of entries in the
701            table from around 16,000 to around 3,000, thus reducing its size
702            considerably. I realized I did not need to use a tree structure after
703            all - a binary chop search is just as efficient. Having reduced the
704            number of entries, I extended their size from 6 bytes to 8 bytes to
705            allow for more data.
706    
707        (d) Added support for Unicode script names via properties such as \p{Han}.
708    
709    19. In UTF-8 mode, a backslash followed by a non-Ascii character was not
710        matching that character.
711    
712    20. When matching a repeated Unicode property with a minimum greater than zero,
713        (for example \pL{2,}), PCRE could look past the end of the subject if it
714        reached it while seeking the minimum number of characters. This could
715        happen only if some of the characters were more than one byte long, because
716        there is a check for at least the minimum number of bytes.
717    
718    21. Refactored the implementation of \p and \P so as to be more general, to
719        allow for more different types of property in future. This has changed the
720        compiled form incompatibly. Anybody with saved compiled patterns that use
721        \p or \P will have to recompile them.
722    
723    22. Added "Any" and "L&" to the supported property types.
724    
725    23. Recognize \x{...} as a code point specifier, even when not in UTF-8 mode,
726        but give a compile time error if the value is greater than 0xff.
727    
728    24. The man pages for pcrepartial, pcreprecompile, and pcre_compile2 were
729        accidentally not being installed or uninstalled.
730    
731    25. The pcre.h file was built from pcre.h.in, but the only changes that were
732        made were to insert the current release number. This seemed silly, because
733        it made things harder for people building PCRE on systems that don't run
734        "configure". I have turned pcre.h into a distributed file, no longer built
735        by "configure", with the version identification directly included. There is
736        no longer a pcre.h.in file.
737    
738        However, this change necessitated a change to the pcre-config script as
739        well. It is built from pcre-config.in, and one of the substitutions was the
740        release number. I have updated configure.ac so that ./configure now finds
741        the release number by grepping pcre.h.
742    
743    26. Added the ability to run the tests under valgrind.
744    
745    
746    Version 6.4 05-Sep-05
747    ---------------------
748    
749     1. Change 6.0/10/(l) to pcregrep introduced a bug that caused separator lines
750        "--" to be printed when multiple files were scanned, even when none of the
751        -A, -B, or -C options were used. This is not compatible with Gnu grep, so I
752        consider it to be a bug, and have restored the previous behaviour.
753    
754     2. A couple of code tidies to get rid of compiler warnings.
755    
756     3. The pcretest program used to cheat by referring to symbols in the library
757        whose names begin with _pcre_. These are internal symbols that are not
758        really supposed to be visible externally, and in some environments it is
759        possible to suppress them. The cheating is now confined to including
760        certain files from the library's source, which is a bit cleaner.
761    
762     4. Renamed pcre.in as pcre.h.in to go with pcrecpp.h.in; it also makes the
763        file's purpose clearer.
764    
765     5. Reorganized pcre_ucp_findchar().
766    
767    
768    Version 6.3 15-Aug-05
769    ---------------------
770    
771     1. The file libpcre.pc.in did not have general read permission in the tarball.
772    
773     2. There were some problems when building without C++ support:
774    
775        (a) If C++ support was not built, "make install" and "make test" still
776            tried to test it.
777    
778        (b) There were problems when the value of CXX was explicitly set. Some
779            changes have been made to try to fix these, and ...
780    
781        (c) --disable-cpp can now be used to explicitly disable C++ support.
782    
783        (d) The use of @CPP_OBJ@ directly caused a blank line preceded by a
784            backslash in a target when C++ was disabled. This confuses some
785            versions of "make", apparently. Using an intermediate variable solves
786            this. (Same for CPP_LOBJ.)
787    
788     3. $(LINK_FOR_BUILD) now includes $(CFLAGS_FOR_BUILD) and $(LINK)
789        (non-Windows) now includes $(CFLAGS) because these flags are sometimes
790        necessary on certain architectures.
791    
792     4. Added a setting of -export-symbols-regex to the link command to remove
793        those symbols that are exported in the C sense, but actually are local
794        within the library, and not documented. Their names all begin with
795        "_pcre_". This is not a perfect job, because (a) we have to except some
796        symbols that pcretest ("illegally") uses, and (b) the facility isn't always
797        available (and never for static libraries). I have made a note to try to
798        find a way round (a) in the future.
799    
800    
801    Version 6.2 01-Aug-05
802    ---------------------
803    
804     1. There was no test for integer overflow of quantifier values. A construction
805        such as {1111111111111111} would give undefined results. What is worse, if
806        a minimum quantifier for a parenthesized subpattern overflowed and became
807        negative, the calculation of the memory size went wrong. This could have
808        led to memory overwriting.
809    
810     2. Building PCRE using VPATH was broken. Hopefully it is now fixed.
811    
812     3. Added "b" to the 2nd argument of fopen() in dftables.c, for non-Unix-like
813        operating environments where this matters.
814    
815     4. Applied Giuseppe Maxia's patch to add additional features for controlling
816        PCRE options from within the C++ wrapper.
817    
818     5. Named capturing subpatterns were not being correctly counted when a pattern
819        was compiled. This caused two problems: (a) If there were more than 100
820        such subpatterns, the calculation of the memory needed for the whole
821        compiled pattern went wrong, leading to an overflow error. (b) Numerical
822        back references of the form \12, where the number was greater than 9, were
823        not recognized as back references, even though there were sufficient
824        previous subpatterns.
825    
826     6. Two minor patches to pcrecpp.cc in order to allow it to compile on older
827        versions of gcc, e.g. 2.95.4.
828    
829    
830    Version 6.1 21-Jun-05
831    ---------------------
832    
833     1. There was one reference to the variable "posix" in pcretest.c that was not
834        surrounded by "#if !defined NOPOSIX".
835    
836     2. Make it possible to compile pcretest without DFA support, UTF8 support, or
837        the cross-check on the old pcre_info() function, for the benefit of the
838        cut-down version of PCRE that is currently imported into Exim.
839    
840     3. A (silly) pattern starting with (?i)(?-i) caused an internal space
841        allocation error. I've done the easy fix, which wastes 2 bytes for sensible
842        patterns that start (?i) but I don't think that matters. The use of (?i) is
843        just an example; this all applies to the other options as well.
844    
845     4. Since libtool seems to echo the compile commands it is issuing, the output
846        from "make" can be reduced a bit by putting "@" in front of each libtool
847        compile command.
848    
849     5. Patch from the folks at Google for configure.in to be a bit more thorough
850        in checking for a suitable C++ installation before trying to compile the
851        C++ stuff. This should fix a reported problem when a compiler was present,
852        but no suitable headers.
853    
854     6. The man pages all had just "PCRE" as their title. I have changed them to
855        be the relevant file name. I have also arranged that these names are
856        retained in the file doc/pcre.txt, which is a concatenation in text format
857        of all the man pages except the little individual ones for each function.
858    
859     7. The NON-UNIX-USE file had not been updated for the different set of source
860        files that come with release 6. I also added a few comments about the C++
861        wrapper.
862    
863    
864    Version 6.0 07-Jun-05
865    ---------------------
866    
867     1. Some minor internal re-organization to help with my DFA experiments.
868    
869     2. Some missing #ifdef SUPPORT_UCP conditionals in pcretest and printint that
870        didn't matter for the library itself when fully configured, but did matter
871        when compiling without UCP support, or within Exim, where the ucp files are
872        not imported.
873    
874     3. Refactoring of the library code to split up the various functions into
875        different source modules. The addition of the new DFA matching code (see
876        below) to a single monolithic source would have made it really too
877        unwieldy, quite apart from causing all the code to be include in a
878        statically linked application, when only some functions are used. This is
879        relevant even without the DFA addition now that patterns can be compiled in
880        one application and matched in another.
881    
882        The downside of splitting up is that there have to be some external
883        functions and data tables that are used internally in different modules of
884        the library but which are not part of the API. These have all had their
885        names changed to start with "_pcre_" so that they are unlikely to clash
886        with other external names.
887    
888     4. Added an alternate matching function, pcre_dfa_exec(), which matches using
889        a different (DFA) algorithm. Although it is slower than the original
890        function, it does have some advantages for certain types of matching
891        problem.
892    
893     5. Upgrades to pcretest in order to test the features of pcre_dfa_exec(),
894        including restarting after a partial match.
895    
896     6. A patch for pcregrep that defines INVALID_FILE_ATTRIBUTES if it is not
897        defined when compiling for Windows was sent to me. I have put it into the
898        code, though I have no means of testing or verifying it.
899    
900     7. Added the pcre_refcount() auxiliary function.
901    
902     8. Added the PCRE_FIRSTLINE option. This constrains an unanchored pattern to
903        match before or at the first newline in the subject string. In pcretest,
904        the /f option on a pattern can be used to set this.
905    
906     9. A repeated \w when used in UTF-8 mode with characters greater than 256
907        would behave wrongly. This has been present in PCRE since release 4.0.
908    
909    10. A number of changes to the pcregrep command:
910    
911        (a) Refactored how -x works; insert ^(...)$ instead of setting
912            PCRE_ANCHORED and checking the length, in preparation for adding
913            something similar for -w.
914    
915        (b) Added the -w (match as a word) option.
916    
917        (c) Refactored the way lines are read and buffered so as to have more
918            than one at a time available.
919    
920        (d) Implemented a pcregrep test script.
921    
922        (e) Added the -M (multiline match) option. This allows patterns to match
923            over several lines of the subject. The buffering ensures that at least
924            8K, or the rest of the document (whichever is the shorter) is available
925            for matching (and similarly the previous 8K for lookbehind assertions).
926    
927        (f) Changed the --help output so that it now says
928    
929              -w, --word-regex(p)
930    
931            instead of two lines, one with "regex" and the other with "regexp"
932            because that confused at least one person since the short forms are the
933            same. (This required a bit of code, as the output is generated
934            automatically from a table. It wasn't just a text change.)
935    
936        (g) -- can be used to terminate pcregrep options if the next thing isn't an
937            option but starts with a hyphen. Could be a pattern or a path name
938            starting with a hyphen, for instance.
939    
940        (h) "-" can be given as a file name to represent stdin.
941    
942        (i) When file names are being printed, "(standard input)" is used for
943            the standard input, for compatibility with GNU grep. Previously
944            "<stdin>" was used.
945    
946        (j) The option --label=xxx can be used to supply a name to be used for
947            stdin when file names are being printed. There is no short form.
948    
949        (k) Re-factored the options decoding logic because we are going to add
950            two more options that take data. Such options can now be given in four
951            different ways, e.g. "-fname", "-f name", "--file=name", "--file name".
952    
953        (l) Added the -A, -B, and -C options for requesting that lines of context
954            around matches be printed.
955    
956        (m) Added the -L option to print the names of files that do not contain
957            any matching lines, that is, the complement of -l.
958    
959        (n) The return code is 2 if any file cannot be opened, but pcregrep does
960            continue to scan other files.
961    
962        (o) The -s option was incorrectly implemented. For compatibility with other
963            greps, it now suppresses the error message for a non-existent or non-
964            accessible file (but not the return code). There is a new option called
965            -q that suppresses the output of matching lines, which was what -s was
966            previously doing.
967    
968        (p) Added --include and --exclude options to specify files for inclusion
969            and exclusion when recursing.
970    
971    11. The Makefile was not using the Autoconf-supported LDFLAGS macro properly.
972        Hopefully, it now does.
973    
974    12. Missing cast in pcre_study().
975    
976    13. Added an "uninstall" target to the makefile.
977    
978    14. Replaced "extern" in the function prototypes in Makefile.in with
979        "PCRE_DATA_SCOPE", which defaults to 'extern' or 'extern "C"' in the Unix
980        world, but is set differently for Windows.
981    
982    15. Added a second compiling function called pcre_compile2(). The only
983        difference is that it has an extra argument, which is a pointer to an
984        integer error code. When there is a compile-time failure, this is set
985        non-zero, in addition to the error test pointer being set to point to an
986        error message. The new argument may be NULL if no error number is required
987        (but then you may as well call pcre_compile(), which is now just a
988        wrapper). This facility is provided because some applications need a
989        numeric error indication, but it has also enabled me to tidy up the way
990        compile-time errors are handled in the POSIX wrapper.
991    
992    16. Added VPATH=.libs to the makefile; this should help when building with one
993        prefix path and installing with another. (Or so I'm told by someone who
994        knows more about this stuff than I do.)
995    
996    17. Added a new option, REG_DOTALL, to the POSIX function regcomp(). This
997        passes PCRE_DOTALL to the pcre_compile() function, making the "." character
998        match everything, including newlines. This is not POSIX-compatible, but
999        somebody wanted the feature. From pcretest it can be activated by using
1000        both the P and the s flags.
1001    
1002    18. AC_PROG_LIBTOOL appeared twice in Makefile.in. Removed one.
1003    
1004    19. libpcre.pc was being incorrectly installed as executable.
1005    
1006    20. A couple of places in pcretest check for end-of-line by looking for '\n';
1007        it now also looks for '\r' so that it will work unmodified on Windows.
1008    
1009    21. Added Google's contributed C++ wrapper to the distribution.
1010    
1011    22. Added some untidy missing memory free() calls in pcretest, to keep
1012        Electric Fence happy when testing.
1013    
1014    
1015    
1016    Version 5.0 13-Sep-04
1017    ---------------------
1018    
1019     1. Internal change: literal characters are no longer packed up into items
1020        containing multiple characters in a single byte-string. Each character
1021        is now matched using a separate opcode. However, there may be more than one
1022        byte in the character in UTF-8 mode.
1023    
1024     2. The pcre_callout_block structure has two new fields: pattern_position and
1025        next_item_length. These contain the offset in the pattern to the next match
1026        item, and its length, respectively.
1027    
1028     3. The PCRE_AUTO_CALLOUT option for pcre_compile() requests the automatic
1029        insertion of callouts before each pattern item. Added the /C option to
1030        pcretest to make use of this.
1031    
1032     4. On the advice of a Windows user, the lines
1033    
1034          #if defined(_WIN32) || defined(WIN32)
1035          _setmode( _fileno( stdout ), 0x8000 );
1036          #endif  /* defined(_WIN32) || defined(WIN32) */
1037    
1038        have been added to the source of pcretest. This apparently does useful
1039        magic in relation to line terminators.
1040    
1041     5. Changed "r" and "w" in the calls to fopen() in pcretest to "rb" and "wb"
1042        for the benefit of those environments where the "b" makes a difference.
1043    
1044     6. The icc compiler has the same options as gcc, but "configure" doesn't seem
1045        to know about it. I have put a hack into configure.in that adds in code
1046        to set GCC=yes if CC=icc. This seems to end up at a point in the
1047        generated configure script that is early enough to affect the setting of
1048        compiler options, which is what is needed, but I have no means of testing
1049        whether it really works. (The user who reported this had patched the
1050        generated configure script, which of course I cannot do.)
1051    
1052        LATER: After change 22 below (new libtool files), the configure script
1053        seems to know about icc (and also ecc). Therefore, I have commented out
1054        this hack in configure.in.
1055    
1056     7. Added support for pkg-config (2 patches were sent in).
1057    
1058     8. Negated POSIX character classes that used a combination of internal tables
1059        were completely broken. These were [[:^alpha:]], [[:^alnum:]], and
1060        [[:^ascii]]. Typically, they would match almost any characters. The other
1061        POSIX classes were not broken in this way.
1062    
1063     9. Matching the pattern "\b.*?" against "ab cd", starting at offset 1, failed
1064        to find the match, as PCRE was deluded into thinking that the match had to
1065        start at the start point or following a newline. The same bug applied to
1066        patterns with negative forward assertions or any backward assertions
1067        preceding ".*" at the start, unless the pattern required a fixed first
1068        character. This was a failing pattern: "(?!.bcd).*". The bug is now fixed.
1069    
1070    10. In UTF-8 mode, when moving forwards in the subject after a failed match
1071        starting at the last subject character, bytes beyond the end of the subject
1072        string were read.
1073    
1074    11. Renamed the variable "class" as "classbits" to make life easier for C++
1075        users. (Previously there was a macro definition, but it apparently wasn't
1076        enough.)
1077    
1078    12. Added the new field "tables" to the extra data so that tables can be passed
1079        in at exec time, or the internal tables can be re-selected. This allows
1080        a compiled regex to be saved and re-used at a later time by a different
1081        program that might have everything at different addresses.
1082    
1083    13. Modified the pcre-config script so that, when run on Solaris, it shows a
1084        -R library as well as a -L library.
1085    
1086    14. The debugging options of pcretest (-d on the command line or D on a
1087        pattern) showed incorrect output for anything following an extended class
1088        that contained multibyte characters and which was followed by a quantifier.
1089    
1090    15. Added optional support for general category Unicode character properties
1091        via the \p, \P, and \X escapes. Unicode property support implies UTF-8
1092        support. It adds about 90K to the size of the library. The meanings of the
1093        inbuilt class escapes such as \d and \s have NOT been changed.
1094    
1095    16. Updated pcredemo.c to include calls to free() to release the memory for the
1096        compiled pattern.
1097    
1098    17. The generated file chartables.c was being created in the source directory
1099        instead of in the building directory. This caused the build to fail if the
1100        source directory was different from the building directory, and was
1101        read-only.
1102    
1103    18. Added some sample Win commands from Mark Tetrode into the NON-UNIX-USE
1104        file. No doubt somebody will tell me if they don't make sense... Also added
1105        Dan Mooney's comments about building on OpenVMS.
1106    
1107    19. Added support for partial matching via the PCRE_PARTIAL option for
1108        pcre_exec() and the \P data escape in pcretest.
1109    
1110    20. Extended pcretest with 3 new pattern features:
1111    
1112        (i)   A pattern option of the form ">rest-of-line" causes pcretest to
1113              write the compiled pattern to the file whose name is "rest-of-line".
1114              This is a straight binary dump of the data, with the saved pointer to
1115              the character tables forced to be NULL. The study data, if any, is
1116              written too. After writing, pcretest reads a new pattern.
1117    
1118        (ii)  If, instead of a pattern, "<rest-of-line" is given, pcretest reads a
1119              compiled pattern from the given file. There must not be any
1120              occurrences of "<" in the file name (pretty unlikely); if there are,
1121              pcretest will instead treat the initial "<" as a pattern delimiter.
1122              After reading in the pattern, pcretest goes on to read data lines as
1123              usual.
1124    
1125        (iii) The F pattern option causes pcretest to flip the bytes in the 32-bit
1126              and 16-bit fields in a compiled pattern, to simulate a pattern that
1127              was compiled on a host of opposite endianness.
1128    
1129    21. The pcre-exec() function can now cope with patterns that were compiled on
1130        hosts of opposite endianness, with this restriction:
1131    
1132          As for any compiled expression that is saved and used later, the tables
1133          pointer field cannot be preserved; the extra_data field in the arguments
1134          to pcre_exec() should be used to pass in a tables address if a value
1135          other than the default internal tables were used at compile time.
1136    
1137    22. Calling pcre_exec() with a negative value of the "ovecsize" parameter is
1138        now diagnosed as an error. Previously, most of the time, a negative number
1139        would have been treated as zero, but if in addition "ovector" was passed as
1140        NULL, a crash could occur.
1141    
1142    23. Updated the files ltmain.sh, config.sub, config.guess, and aclocal.m4 with
1143        new versions from the libtool 1.5 distribution (the last one is a copy of
1144        a file called libtool.m4). This seems to have fixed the need to patch
1145        "configure" to support Darwin 1.3 (which I used to do). However, I still
1146        had to patch ltmain.sh to ensure that ${SED} is set (it isn't on my
1147        workstation).
1148    
1149    24. Changed the PCRE licence to be the more standard "BSD" licence.
1150    
1151    
1152    Version 4.5 01-Dec-03
1153    ---------------------
1154    
1155     1. There has been some re-arrangement of the code for the match() function so
1156        that it can be compiled in a version that does not call itself recursively.
1157        Instead, it keeps those local variables that need separate instances for
1158        each "recursion" in a frame on the heap, and gets/frees frames whenever it
1159        needs to "recurse". Keeping track of where control must go is done by means
1160        of setjmp/longjmp. The whole thing is implemented by a set of macros that
1161        hide most of the details from the main code, and operates only if
1162        NO_RECURSE is defined while compiling pcre.c. If PCRE is built using the
1163        "configure" mechanism, "--disable-stack-for-recursion" turns on this way of
1164        operating.
1165    
1166        To make it easier for callers to provide specially tailored get/free
1167        functions for this usage, two new functions, pcre_stack_malloc, and
1168        pcre_stack_free, are used. They are always called in strict stacking order,
1169        and the size of block requested is always the same.
1170    
1171        The PCRE_CONFIG_STACKRECURSE info parameter can be used to find out whether
1172        PCRE has been compiled to use the stack or the heap for recursion. The
1173        -C option of pcretest uses this to show which version is compiled.
1174    
1175        A new data escape \S, is added to pcretest; it causes the amounts of store
1176        obtained and freed by both kinds of malloc/free at match time to be added
1177        to the output.
1178    
1179     2. Changed the locale test to use "fr_FR" instead of "fr" because that's
1180        what's available on my current Linux desktop machine.
1181    
1182     3. When matching a UTF-8 string, the test for a valid string at the start has
1183        been extended. If start_offset is not zero, PCRE now checks that it points
1184        to a byte that is the start of a UTF-8 character. If not, it returns
1185        PCRE_ERROR_BADUTF8_OFFSET (-11). Note: the whole string is still checked;
1186        this is necessary because there may be backward assertions in the pattern.
1187        When matching the same subject several times, it may save resources to use
1188        PCRE_NO_UTF8_CHECK on all but the first call if the string is long.
1189    
1190     4. The code for checking the validity of UTF-8 strings has been tightened so
1191        that it rejects (a) strings containing 0xfe or 0xff bytes and (b) strings
1192        containing "overlong sequences".
1193    
1194     5. Fixed a bug (appearing twice) that I could not find any way of exploiting!
1195        I had written "if ((digitab[*p++] && chtab_digit) == 0)" where the "&&"
1196        should have been "&", but it just so happened that all the cases this let
1197        through by mistake were picked up later in the function.
1198    
1199     6. I had used a variable called "isblank" - this is a C99 function, causing
1200        some compilers to warn. To avoid this, I renamed it (as "blankclass").
1201    
1202     7. Cosmetic: (a) only output another newline at the end of pcretest if it is
1203        prompting; (b) run "./pcretest /dev/null" at the start of the test script
1204        so the version is shown; (c) stop "make test" echoing "./RunTest".
1205    
1206     8. Added patches from David Burgess to enable PCRE to run on EBCDIC systems.
1207    
1208     9. The prototype for memmove() for systems that don't have it was using
1209        size_t, but the inclusion of the header that defines size_t was later. I've
1210        moved the #includes for the C headers earlier to avoid this.
1211    
1212    10. Added some adjustments to the code to make it easier to compiler on certain
1213        special systems:
1214    
1215          (a) Some "const" qualifiers were missing.
1216          (b) Added the macro EXPORT before all exported functions; by default this
1217              is defined to be empty.
1218          (c) Changed the dftables auxiliary program (that builds chartables.c) so
1219              that it reads its output file name as an argument instead of writing
1220              to the standard output and assuming this can be redirected.
1221    
1222    11. In UTF-8 mode, if a recursive reference (e.g. (?1)) followed a character
1223        class containing characters with values greater than 255, PCRE compilation
1224        went into a loop.
1225    
1226    12. A recursive reference to a subpattern that was within another subpattern
1227        that had a minimum quantifier of zero caused PCRE to crash. For example,
1228        (x(y(?2))z)? provoked this bug with a subject that got as far as the
1229        recursion. If the recursively-called subpattern itself had a zero repeat,
1230        that was OK.
1231    
1232    13. In pcretest, the buffer for reading a data line was set at 30K, but the
1233        buffer into which it was copied (for escape processing) was still set at
1234        1024, so long lines caused crashes.
1235    
1236    14. A pattern such as /[ab]{1,3}+/ failed to compile, giving the error
1237        "internal error: code overflow...". This applied to any character class
1238        that was followed by a possessive quantifier.
1239    
1240    15. Modified the Makefile to add libpcre.la as a prerequisite for
1241        libpcreposix.la because I was told this is needed for a parallel build to
1242        work.
1243    
1244    16. If a pattern that contained .* following optional items at the start was
1245        studied, the wrong optimizing data was generated, leading to matching
1246        errors. For example, studying /[ab]*.*c/ concluded, erroneously, that any
1247        matching string must start with a or b or c. The correct conclusion for
1248        this pattern is that a match can start with any character.
1249    
1250    
1251    Version 4.4 13-Aug-03
1252    ---------------------
1253    
1254     1. In UTF-8 mode, a character class containing characters with values between
1255        127 and 255 was not handled correctly if the compiled pattern was studied.
1256        In fixing this, I have also improved the studying algorithm for such
1257        classes (slightly).
1258    
1259     2. Three internal functions had redundant arguments passed to them. Removal
1260        might give a very teeny performance improvement.
1261    
1262     3. Documentation bug: the value of the capture_top field in a callout is *one
1263        more than* the number of the hightest numbered captured substring.
1264    
1265     4. The Makefile linked pcretest and pcregrep with -lpcre, which could result
1266        in incorrectly linking with a previously installed version. They now link
1267        explicitly with libpcre.la.
1268    
1269     5. configure.in no longer needs to recognize Cygwin specially.
1270    
1271     6. A problem in pcre.in for Windows platforms is fixed.
1272    
1273     7. If a pattern was successfully studied, and the -d (or /D) flag was given to
1274        pcretest, it used to include the size of the study block as part of its
1275        output. Unfortunately, the structure contains a field that has a different
1276        size on different hardware architectures. This meant that the tests that
1277        showed this size failed. As the block is currently always of a fixed size,
1278        this information isn't actually particularly useful in pcretest output, so
1279        I have just removed it.
1280    
1281     8. Three pre-processor statements accidentally did not start in column 1.
1282        Sadly, there are *still* compilers around that complain, even though
1283        standard C has not required this for well over a decade. Sigh.
1284    
1285     9. In pcretest, the code for checking callouts passed small integers in the
1286        callout_data field, which is a void * field. However, some picky compilers
1287        complained about the casts involved for this on 64-bit systems. Now
1288        pcretest passes the address of the small integer instead, which should get
1289        rid of the warnings.
1290    
1291    10. By default, when in UTF-8 mode, PCRE now checks for valid UTF-8 strings at
1292        both compile and run time, and gives an error if an invalid UTF-8 sequence
1293        is found. There is a option for disabling this check in cases where the
1294        string is known to be correct and/or the maximum performance is wanted.
1295    
1296    11. In response to a bug report, I changed one line in Makefile.in from
1297    
1298            -Wl,--out-implib,.libs/lib@WIN_PREFIX@pcreposix.dll.a \
1299        to
1300            -Wl,--out-implib,.libs/@WIN_PREFIX@libpcreposix.dll.a \
1301    
1302        to look similar to other lines, but I have no way of telling whether this
1303        is the right thing to do, as I do not use Windows. No doubt I'll get told
1304        if it's wrong...
1305    
1306    
1307    Version 4.3 21-May-03
1308    ---------------------
1309    
1310    1. Two instances of @WIN_PREFIX@ omitted from the Windows targets in the
1311       Makefile.
1312    
1313    2. Some refactoring to improve the quality of the code:
1314    
1315       (i)   The utf8_table... variables are now declared "const".
1316    
1317       (ii)  The code for \cx, which used the "case flipping" table to upper case
1318             lower case letters, now just substracts 32. This is ASCII-specific,
1319             but the whole concept of \cx is ASCII-specific, so it seems
1320             reasonable.
1321    
1322       (iii) PCRE was using its character types table to recognize decimal and
1323             hexadecimal digits in the pattern. This is silly, because it handles
1324             only 0-9, a-f, and A-F, but the character types table is locale-
1325             specific, which means strange things might happen. A private
1326             table is now used for this - though it costs 256 bytes, a table is
1327             much faster than multiple explicit tests. Of course, the standard
1328             character types table is still used for matching digits in subject
1329             strings against \d.
1330    
1331       (iv)  Strictly, the identifier ESC_t is reserved by POSIX (all identifiers
1332             ending in _t are). So I've renamed it as ESC_tee.
1333    
1334    3. The first argument for regexec() in the POSIX wrapper should have been
1335       defined as "const".
1336    
1337    4. Changed pcretest to use malloc() for its buffers so that they can be
1338       Electric Fenced for debugging.
1339    
1340    5. There were several places in the code where, in UTF-8 mode, PCRE would try
1341       to read one or more bytes before the start of the subject string. Often this
1342       had no effect on PCRE's behaviour, but in some circumstances it could
1343       provoke a segmentation fault.
1344    
1345    6. A lookbehind at the start of a pattern in UTF-8 mode could also cause PCRE
1346       to try to read one or more bytes before the start of the subject string.
1347    
1348    7. A lookbehind in a pattern matched in non-UTF-8 mode on a PCRE compiled with
1349       UTF-8 support could misbehave in various ways if the subject string
1350       contained bytes with the 0x80 bit set and the 0x40 bit unset in a lookbehind
1351       area. (PCRE was not checking for the UTF-8 mode flag, and trying to move
1352       back over UTF-8 characters.)
1353    
1354    
1355    Version 4.2 14-Apr-03
1356    ---------------------
1357    
1358    1. Typo "#if SUPPORT_UTF8" instead of "#ifdef SUPPORT_UTF8" fixed.
1359    
1360    2. Changes to the building process, supplied by Ronald Landheer-Cieslak
1361         [ON_WINDOWS]: new variable, "#" on non-Windows platforms
1362         [NOT_ON_WINDOWS]: new variable, "#" on Windows platforms
1363         [WIN_PREFIX]: new variable, "cyg" for Cygwin
1364         * Makefile.in: use autoconf substitution for OBJEXT, EXEEXT, BUILD_OBJEXT
1365           and BUILD_EXEEXT
1366         Note: automatic setting of the BUILD variables is not yet working
1367         set CPPFLAGS and BUILD_CPPFLAGS (but don't use yet) - should be used at
1368           compile-time but not at link-time
1369         [LINK]: use for linking executables only
1370         make different versions for Windows and non-Windows
1371         [LINKLIB]: new variable, copy of UNIX-style LINK, used for linking
1372           libraries
1373         [LINK_FOR_BUILD]: new variable
1374         [OBJEXT]: use throughout
1375         [EXEEXT]: use throughout
1376         <winshared>: new target
1377         <wininstall>: new target
1378         <dftables.o>: use native compiler
1379         <dftables>: use native linker
1380         <install>: handle Windows platform correctly
1381         <clean>: ditto
1382         <check>: ditto
1383         copy DLL to top builddir before testing
1384    
1385       As part of these changes, -no-undefined was removed again. This was reported
1386       to give trouble on HP-UX 11.0, so getting rid of it seems like a good idea
1387       in any case.
1388    
1389    3. Some tidies to get rid of compiler warnings:
1390    
1391       . In the match_data structure, match_limit was an unsigned long int, whereas
1392         match_call_count was an int. I've made them both unsigned long ints.
1393    
1394       . In pcretest the fact that a const uschar * doesn't automatically cast to
1395         a void * provoked a warning.
1396    
1397       . Turning on some more compiler warnings threw up some "shadow" variables
1398         and a few more missing casts.
1399    
1400    4. If PCRE was complied with UTF-8 support, but called without the PCRE_UTF8
1401       option, a class that contained a single character with a value between 128
1402       and 255 (e.g. /[\xFF]/) caused PCRE to crash.
1403    
1404    5. If PCRE was compiled with UTF-8 support, but called without the PCRE_UTF8
1405       option, a class that contained several characters, but with at least one
1406       whose value was between 128 and 255 caused PCRE to crash.
1407    
1408    
1409    Version 4.1 12-Mar-03
1410    ---------------------
1411    
1412    1. Compiling with gcc -pedantic found a couple of places where casts were
1413    needed, and a string in dftables.c that was longer than standard compilers are
1414    required to support.
1415    
1416    2. Compiling with Sun's compiler found a few more places where the code could
1417    be tidied up in order to avoid warnings.
1418    
1419    3. The variables for cross-compiling were called HOST_CC and HOST_CFLAGS; the
1420    first of these names is deprecated in the latest Autoconf in favour of the name
1421    CC_FOR_BUILD, because "host" is typically used to mean the system on which the
1422    compiled code will be run. I can't find a reference for HOST_CFLAGS, but by
1423    analogy I have changed it to CFLAGS_FOR_BUILD.
1424    
1425    4. Added -no-undefined to the linking command in the Makefile, because this is
1426    apparently helpful for Windows. To make it work, also added "-L. -lpcre" to the
1427    linking step for the pcreposix library.
1428    
1429    5. PCRE was failing to diagnose the case of two named groups with the same
1430    name.
1431    
1432    6. A problem with one of PCRE's optimizations was discovered. PCRE remembers a
1433    literal character that is needed in the subject for a match, and scans along to
1434    ensure that it is present before embarking on the full matching process. This
1435    saves time in cases of nested unlimited repeats that are never going to match.
1436    Problem: the scan can take a lot of time if the subject is very long (e.g.
1437    megabytes), thus penalizing straightforward matches. It is now done only if the
1438    amount of subject to be scanned is less than 1000 bytes.
1439    
1440    7. A lesser problem with the same optimization is that it was recording the
1441    first character of an anchored pattern as "needed", thus provoking a search
1442    right along the subject, even when the first match of the pattern was going to
1443    fail. The "needed" character is now not set for anchored patterns, unless it
1444    follows something in the pattern that is of non-fixed length. Thus, it still
1445    fulfils its original purpose of finding quick non-matches in cases of nested
1446    unlimited repeats, but isn't used for simple anchored patterns such as /^abc/.
1447    
1448    
1449    Version 4.0 17-Feb-03
1450    ---------------------
1451    
1452    1. If a comment in an extended regex that started immediately after a meta-item
1453    extended to the end of string, PCRE compiled incorrect data. This could lead to
1454    all kinds of weird effects. Example: /#/ was bad; /()#/ was bad; /a#/ was not.
1455    
1456    2. Moved to autoconf 2.53 and libtool 1.4.2.
1457    
1458    3. Perl 5.8 no longer needs "use utf8" for doing UTF-8 things. Consequently,
1459    the special perltest8 script is no longer needed - all the tests can be run
1460    from a single perltest script.
1461    
1462    4. From 5.004, Perl has not included the VT character (0x0b) in the set defined
1463    by \s. It has now been removed in PCRE. This means it isn't recognized as
1464    whitespace in /x regexes too, which is the same as Perl. Note that the POSIX
1465    class [:space:] *does* include VT, thereby creating a mess.
1466    
1467    5. Added the class [:blank:] (a GNU extension from Perl 5.8) to match only
1468    space and tab.
1469    
1470    6. Perl 5.005 was a long time ago. It's time to amalgamate the tests that use
1471    its new features into the main test script, reducing the number of scripts.
1472    
1473    7. Perl 5.8 has changed the meaning of patterns like /a(?i)b/. Earlier versions
1474    were backward compatible, and made the (?i) apply to the whole pattern, as if
1475    /i were given. Now it behaves more logically, and applies the option setting
1476    only to what follows. PCRE has been changed to follow suit. However, if it
1477    finds options settings right at the start of the pattern, it extracts them into
1478    the global options, as before. Thus, they show up in the info data.
1479    
1480    8. Added support for the \Q...\E escape sequence. Characters in between are
1481    treated as literals. This is slightly different from Perl in that $ and @ are
1482    also handled as literals inside the quotes. In Perl, they will cause variable
1483    interpolation. Note the following examples:
1484    
1485        Pattern            PCRE matches      Perl matches
1486    
1487        \Qabc$xyz\E        abc$xyz           abc followed by the contents of $xyz
1488        \Qabc\$xyz\E       abc\$xyz          abc\$xyz
1489        \Qabc\E\$\Qxyz\E   abc$xyz           abc$xyz
1490    
1491    For compatibility with Perl, \Q...\E sequences are recognized inside character
1492    classes as well as outside them.
1493    
1494    9. Re-organized 3 code statements in pcretest to avoid "overflow in
1495    floating-point constant arithmetic" warnings from a Microsoft compiler. Added a
1496    (size_t) cast to one statement in pcretest and one in pcreposix to avoid
1497    signed/unsigned warnings.
1498    
1499    10. SunOS4 doesn't have strtoul(). This was used only for unpicking the -o
1500    option for pcretest, so I've replaced it by a simple function that does just
1501    that job.
1502    
1503    11. pcregrep was ending with code 0 instead of 2 for the commands "pcregrep" or
1504    "pcregrep -".
1505    
1506    12. Added "possessive quantifiers" ?+, *+, ++, and {,}+ which come from Sun's
1507    Java package. This provides some syntactic sugar for simple cases of what my
1508    documentation calls "once-only subpatterns". A pattern such as x*+ is the same
1509    as (?>x*). In other words, if what is inside (?>...) is just a single repeated
1510    item, you can use this simplified notation. Note that only makes sense with
1511    greedy quantifiers. Consequently, the use of the possessive quantifier forces
1512    greediness, whatever the setting of the PCRE_UNGREEDY option.
1513    
1514    13. A change of greediness default within a pattern was not taking effect at
1515    the current level for patterns like /(b+(?U)a+)/. It did apply to parenthesized
1516    subpatterns that followed. Patterns like /b+(?U)a+/ worked because the option
1517    was abstracted outside.
1518    
1519    14. PCRE now supports the \G assertion. It is true when the current matching
1520    position is at the start point of the match. This differs from \A when the
1521    starting offset is non-zero. Used with the /g option of pcretest (or similar
1522    code), it works in the same way as it does for Perl's /g option. If all
1523    alternatives of a regex begin with \G, the expression is anchored to the start
1524    match position, and the "anchored" flag is set in the compiled expression.
1525    
1526    15. Some bugs concerning the handling of certain option changes within patterns
1527    have been fixed. These applied to options other than (?ims). For example,
1528    "a(?x: b c )d" did not match "XabcdY" but did match "Xa b c dY". It should have
1529    been the other way round. Some of this was related to change 7 above.
1530    
1531    16. PCRE now gives errors for /[.x.]/ and /[=x=]/ as unsupported POSIX
1532    features, as Perl does. Previously, PCRE gave the warnings only for /[[.x.]]/
1533    and /[[=x=]]/. PCRE now also gives an error for /[:name:]/ because it supports
1534    POSIX classes only within a class (e.g. /[[:alpha:]]/).
1535    
1536    17. Added support for Perl's \C escape. This matches one byte, even in UTF8
1537    mode. Unlike ".", it always matches newline, whatever the setting of
1538    PCRE_DOTALL. However, PCRE does not permit \C to appear in lookbehind
1539    assertions. Perl allows it, but it doesn't (in general) work because it can't
1540    calculate the length of the lookbehind. At least, that's the case for Perl
1541    5.8.0 - I've been told they are going to document that it doesn't work in
1542    future.
1543    
1544    18. Added an error diagnosis for escapes that PCRE does not support: these are
1545    \L, \l, \N, \P, \p, \U, \u, and \X.
1546    
1547    19. Although correctly diagnosing a missing ']' in a character class, PCRE was
1548    reading past the end of the pattern in cases such as /[abcd/.
1549    
1550    20. PCRE was getting more memory than necessary for patterns with classes that
1551    contained both POSIX named classes and other characters, e.g. /[[:space:]abc/.
1552    
1553    21. Added some code, conditional on #ifdef VPCOMPAT, to make life easier for
1554    compiling PCRE for use with Virtual Pascal.
1555    
1556    22. Small fix to the Makefile to make it work properly if the build is done
1557    outside the source tree.
1558    
1559    23. Added a new extension: a condition to go with recursion. If a conditional
1560    subpattern starts with (?(R) the "true" branch is used if recursion has
1561    happened, whereas the "false" branch is used only at the top level.
1562    
1563    24. When there was a very long string of literal characters (over 255 bytes
1564    without UTF support, over 250 bytes with UTF support), the computation of how
1565    much memory was required could be incorrect, leading to segfaults or other
1566    strange effects.
1567    
1568    25. PCRE was incorrectly assuming anchoring (either to start of subject or to
1569    start of line for a non-DOTALL pattern) when a pattern started with (.*) and
1570    there was a subsequent back reference to those brackets. This meant that, for
1571    example, /(.*)\d+\1/ failed to match "abc123bc". Unfortunately, it isn't
1572    possible to check for precisely this case. All we can do is abandon the
1573    optimization if .* occurs inside capturing brackets when there are any back
1574    references whatsoever. (See below for a better fix that came later.)
1575    
1576    26. The handling of the optimization for finding the first character of a
1577    non-anchored pattern, and for finding a character that is required later in the
1578    match were failing in some cases. This didn't break the matching; it just
1579    failed to optimize when it could. The way this is done has been re-implemented.
1580    
1581    27. Fixed typo in error message for invalid (?R item (it said "(?p").
1582    
1583    28. Added a new feature that provides some of the functionality that Perl
1584    provides with (?{...}). The facility is termed a "callout". The way it is done
1585    in PCRE is for the caller to provide an optional function, by setting
1586    pcre_callout to its entry point. Like pcre_malloc and pcre_free, this is a
1587    global variable. By default it is unset, which disables all calling out. To get
1588    the function called, the regex must include (?C) at appropriate points. This
1589    is, in fact, equivalent to (?C0), and any number <= 255 may be given with (?C).
1590    This provides a means of identifying different callout points. When PCRE
1591    reaches such a point in the regex, if pcre_callout has been set, the external
1592    function is called. It is provided with data in a structure called
1593    pcre_callout_block, which is defined in pcre.h. If the function returns 0,
1594    matching continues; if it returns a non-zero value, the match at the current
1595    point fails. However, backtracking will occur if possible. [This was changed
1596    later and other features added - see item 49 below.]
1597    
1598    29. pcretest is upgraded to test the callout functionality. It provides a
1599    callout function that displays information. By default, it shows the start of
1600    the match and the current position in the text. There are some new data escapes
1601    to vary what happens:
1602    
1603        \C+         in addition, show current contents of captured substrings
1604        \C-         do not supply a callout function
1605        \C!n        return 1 when callout number n is reached
1606        \C!n!m      return 1 when callout number n is reached for the mth time
1607    
1608    30. If pcregrep was called with the -l option and just a single file name, it
1609    output "<stdin>" if a match was found, instead of the file name.
1610    
1611    31. Improve the efficiency of the POSIX API to PCRE. If the number of capturing
1612    slots is less than POSIX_MALLOC_THRESHOLD, use a block on the stack to pass to
1613    pcre_exec(). This saves a malloc/free per call. The default value of
1614    POSIX_MALLOC_THRESHOLD is 10; it can be changed by --with-posix-malloc-threshold
1615    when configuring.
1616    
1617    32. The default maximum size of a compiled pattern is 64K. There have been a
1618    few cases of people hitting this limit. The code now uses macros to handle the
1619    storing of links as offsets within the compiled pattern. It defaults to 2-byte
1620    links, but this can be changed to 3 or 4 bytes by --with-link-size when
1621    configuring. Tests 2 and 5 work only with 2-byte links because they output
1622    debugging information about compiled patterns.
1623    
1624    33. Internal code re-arrangements:
1625    
1626    (a) Moved the debugging function for printing out a compiled regex into
1627        its own source file (printint.c) and used #include to pull it into
1628        pcretest.c and, when DEBUG is defined, into pcre.c, instead of having two
1629        separate copies.
1630    
1631    (b) Defined the list of op-code names for debugging as a macro in
1632        internal.h so that it is next to the definition of the opcodes.
1633    
1634    (c) Defined a table of op-code lengths for simpler skipping along compiled
1635        code. This is again a macro in internal.h so that it is next to the
1636        definition of the opcodes.
1637    
1638    34. Added support for recursive calls to individual subpatterns, along the
1639    lines of Robin Houston's patch (but implemented somewhat differently).
1640    
1641    35. Further mods to the Makefile to help Win32. Also, added code to pcregrep to
1642    allow it to read and process whole directories in Win32. This code was
1643    contributed by Lionel Fourquaux; it has not been tested by me.
1644    
1645    36. Added support for named subpatterns. The Python syntax (?P<name>...) is
1646    used to name a group. Names consist of alphanumerics and underscores, and must
1647    be unique. Back references use the syntax (?P=name) and recursive calls use
1648    (?P>name) which is a PCRE extension to the Python extension. Groups still have
1649    numbers. The function pcre_fullinfo() can be used after compilation to extract
1650    a name/number map. There are three relevant calls:
1651    
1652      PCRE_INFO_NAMEENTRYSIZE        yields the size of each entry in the map
1653      PCRE_INFO_NAMECOUNT            yields the number of entries
1654      PCRE_INFO_NAMETABLE            yields a pointer to the map.
1655    
1656    The map is a vector of fixed-size entries. The size of each entry depends on
1657    the length of the longest name used. The first two bytes of each entry are the
1658    group number, most significant byte first. There follows the corresponding
1659    name, zero terminated. The names are in alphabetical order.
1660    
1661    37. Make the maximum literal string in the compiled code 250 for the non-UTF-8
1662    case instead of 255. Making it the same both with and without UTF-8 support
1663    means that the same test output works with both.
1664    
1665    38. There was a case of malloc(0) in the POSIX testing code in pcretest. Avoid
1666    calling malloc() with a zero argument.
1667    
1668    39. Change 25 above had to resort to a heavy-handed test for the .* anchoring
1669    optimization. I've improved things by keeping a bitmap of backreferences with
1670    numbers 1-31 so that if .* occurs inside capturing brackets that are not in
1671    fact referenced, the optimization can be applied. It is unlikely that a
1672    relevant occurrence of .* (i.e. one which might indicate anchoring or forcing
1673    the match to follow \n) will appear inside brackets with a number greater than
1674    31, but if it does, any back reference > 31 suppresses the optimization.
1675    
1676    40. Added a new compile-time option PCRE_NO_AUTO_CAPTURE. This has the effect
1677    of disabling numbered capturing parentheses. Any opening parenthesis that is
1678    not followed by ? behaves as if it were followed by ?: but named parentheses
1679    can still be used for capturing (and they will acquire numbers in the usual
1680    way).
1681    
1682    41. Redesigned the return codes from the match() function into yes/no/error so
1683    that errors can be passed back from deep inside the nested calls. A malloc
1684    failure while inside a recursive subpattern call now causes the
1685    PCRE_ERROR_NOMEMORY return instead of quietly going wrong.
1686    
1687    42. It is now possible to set a limit on the number of times the match()
1688    function is called in a call to pcre_exec(). This facility makes it possible to
1689    limit the amount of recursion and backtracking, though not in a directly
1690    obvious way, because the match() function is used in a number of different
1691    circumstances. The count starts from zero for each position in the subject
1692    string (for non-anchored patterns). The default limit is, for compatibility, a
1693    large number, namely 10 000 000. You can change this in two ways:
1694    
1695    (a) When configuring PCRE before making, you can use --with-match-limit=n
1696        to set a default value for the compiled library.
1697    
1698    (b) For each call to pcre_exec(), you can pass a pcre_extra block in which
1699        a different value is set. See 45 below.
1700    
1701    If the limit is exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT.
1702    
1703    43. Added a new function pcre_config(int, void *) to enable run-time extraction
1704    of things that can be changed at compile time. The first argument specifies
1705    what is wanted and the second points to where the information is to be placed.
1706    The current list of available information is:
1707    
1708      PCRE_CONFIG_UTF8
1709    
1710    The output is an integer that is set to one if UTF-8 support is available;
1711    otherwise it is set to zero.
1712    
1713      PCRE_CONFIG_NEWLINE
1714    
1715    The output is an integer that it set to the value of the code that is used for
1716    newline. It is either LF (10) or CR (13).
1717    
1718      PCRE_CONFIG_LINK_SIZE
1719    
1720    The output is an integer that contains the number of bytes used for internal
1721    linkage in compiled expressions. The value is 2, 3, or 4. See item 32 above.
1722    
1723      PCRE_CONFIG_POSIX_MALLOC_THRESHOLD
1724    
1725    The output is an integer that contains the threshold above which the POSIX
1726    interface uses malloc() for output vectors. See item 31 above.
1727    
1728      PCRE_CONFIG_MATCH_LIMIT
1729    
1730    The output is an unsigned integer that contains the default limit of the number
1731    of match() calls in a pcre_exec() execution. See 42 above.
1732    
1733    44. pcretest has been upgraded by the addition of the -C option. This causes it
1734    to extract all the available output from the new pcre_config() function, and to
1735    output it. The program then exits immediately.
1736    
1737    45. A need has arisen to pass over additional data with calls to pcre_exec() in
1738    order to support additional features. One way would have been to define
1739    pcre_exec2() (for example) with extra arguments, but this would not have been
1740    extensible, and would also have required all calls to the original function to
1741    be mapped to the new one. Instead, I have chosen to extend the mechanism that
1742    is used for passing in "extra" data from pcre_study().
1743    
1744    The pcre_extra structure is now exposed and defined in pcre.h. It currently
1745    contains the following fields:
1746    
1747      flags         a bitmap indicating which of the following fields are set
1748      study_data    opaque data from pcre_study()
1749      match_limit   a way of specifying a limit on match() calls for a specific
1750                      call to pcre_exec()
1751      callout_data  data for callouts (see 49 below)
1752    
1753    The flag bits are also defined in pcre.h, and are
1754    
1755      PCRE_EXTRA_STUDY_DATA
1756      PCRE_EXTRA_MATCH_LIMIT
1757      PCRE_EXTRA_CALLOUT_DATA
1758    
1759    The pcre_study() function now returns one of these new pcre_extra blocks, with
1760    the actual study data pointed to by the study_data field, and the
1761    PCRE_EXTRA_STUDY_DATA flag set. This can be passed directly to pcre_exec() as
1762    before. That is, this change is entirely upwards-compatible and requires no
1763    change to existing code.
1764    
1765    If you want to pass in additional data to pcre_exec(), you can either place it
1766    in a pcre_extra block provided by pcre_study(), or create your own pcre_extra
1767    block.
1768    
1769    46. pcretest has been extended to test the PCRE_EXTRA_MATCH_LIMIT feature. If a
1770    data string contains the escape sequence \M, pcretest calls pcre_exec() several
1771    times with different match limits, until it finds the minimum value needed for
1772    pcre_exec() to complete. The value is then output. This can be instructive; for
1773    most simple matches the number is quite small, but for pathological cases it
1774    gets very large very quickly.
1775    
1776    47. There's a new option for pcre_fullinfo() called PCRE_INFO_STUDYSIZE. It
1777    returns the size of the data block pointed to by the study_data field in a
1778    pcre_extra block, that is, the value that was passed as the argument to
1779    pcre_malloc() when PCRE was getting memory in which to place the information
1780    created by pcre_study(). The fourth argument should point to a size_t variable.
1781    pcretest has been extended so that this information is shown after a successful
1782    pcre_study() call when information about the compiled regex is being displayed.
1783    
1784    48. Cosmetic change to Makefile: there's no need to have / after $(DESTDIR)
1785    because what follows is always an absolute path. (Later: it turns out that this
1786    is more than cosmetic for MinGW, because it doesn't like empty path
1787    components.)
1788    
1789    49. Some changes have been made to the callout feature (see 28 above):
1790    
1791    (i)  A callout function now has three choices for what it returns:
1792    
1793           0  =>  success, carry on matching
1794         > 0  =>  failure at this point, but backtrack if possible
1795         < 0  =>  serious error, return this value from pcre_exec()
1796    
1797         Negative values should normally be chosen from the set of PCRE_ERROR_xxx
1798         values. In particular, returning PCRE_ERROR_NOMATCH forces a standard
1799         "match failed" error. The error number PCRE_ERROR_CALLOUT is reserved for
1800         use by callout functions. It will never be used by PCRE itself.
1801    
1802    (ii) The pcre_extra structure (see 45 above) has a void * field called
1803         callout_data, with corresponding flag bit PCRE_EXTRA_CALLOUT_DATA. The
1804         pcre_callout_block structure has a field of the same name. The contents of
1805         the field passed in the pcre_extra structure are passed to the callout
1806         function in the corresponding field in the callout block. This makes it
1807         easier to use the same callout-containing regex from multiple threads. For
1808         testing, the pcretest program has a new data escape
1809    
1810           \C*n        pass the number n (may be negative) as callout_data
1811    
1812         If the callout function in pcretest receives a non-zero value as
1813         callout_data, it returns that value.
1814    
1815    50. Makefile wasn't handling CFLAGS properly when compiling dftables. Also,
1816    there were some redundant $(CFLAGS) in commands that are now specified as
1817    $(LINK), which already includes $(CFLAGS).
1818    
1819    51. Extensions to UTF-8 support are listed below. These all apply when (a) PCRE
1820    has been compiled with UTF-8 support *and* pcre_compile() has been compiled
1821    with the PCRE_UTF8 flag. Patterns that are compiled without that flag assume
1822    one-byte characters throughout. Note that case-insensitive matching applies
1823    only to characters whose values are less than 256. PCRE doesn't support the
1824    notion of cases for higher-valued characters.
1825    
1826    (i)   A character class whose characters are all within 0-255 is handled as
1827          a bit map, and the map is inverted for negative classes. Previously, a
1828          character > 255 always failed to match such a class; however it should
1829          match if the class was a negative one (e.g. [^ab]). This has been fixed.
1830    
1831    (ii)  A negated character class with a single character < 255 is coded as
1832          "not this character" (OP_NOT). This wasn't working properly when the test
1833          character was multibyte, either singly or repeated.
1834    
1835    (iii) Repeats of multibyte characters are now handled correctly in UTF-8
1836          mode, for example: \x{100}{2,3}.
1837    
1838    (iv)  The character escapes \b, \B, \d, \D, \s, \S, \w, and \W (either
1839          singly or repeated) now correctly test multibyte characters. However,
1840          PCRE doesn't recognize any characters with values greater than 255 as
1841          digits, spaces, or word characters. Such characters always match \D, \S,
1842          and \W, and never match \d, \s, or \w.
1843    
1844    (v)   Classes may now contain characters and character ranges with values
1845          greater than 255. For example: [ab\x{100}-\x{400}].
1846    
1847    (vi)  pcregrep now has a --utf-8 option (synonym -u) which makes it call
1848          PCRE in UTF-8 mode.
1849    
1850    52. The info request value PCRE_INFO_FIRSTCHAR has been renamed
1851    PCRE_INFO_FIRSTBYTE because it is a byte value. However, the old name is
1852    retained for backwards compatibility. (Note that LASTLITERAL is also a byte
1853    value.)
1854    
1855    53. The single man page has become too large. I have therefore split it up into
1856    a number of separate man pages. These also give rise to individual HTML pages;
1857    these are now put in a separate directory, and there is an index.html page that
1858    lists them all. Some hyperlinking between the pages has been installed.
1859    
1860    54. Added convenience functions for handling named capturing parentheses.
1861    
1862    55. Unknown escapes inside character classes (e.g. [\M]) and escapes that
1863    aren't interpreted therein (e.g. [\C]) are literals in Perl. This is now also
1864    true in PCRE, except when the PCRE_EXTENDED option is set, in which case they
1865    are faulted.
1866    
1867    56. Introduced HOST_CC and HOST_CFLAGS which can be set in the environment when
1868    calling configure. These values are used when compiling the dftables.c program
1869    which is run to generate the source of the default character tables. They
1870    default to the values of CC and CFLAGS. If you are cross-compiling PCRE,
1871    you will need to set these values.
1872    
1873    57. Updated the building process for Windows DLL, as provided by Fred Cox.
1874    
1875    
1876    Version 3.9 02-Jan-02
1877    ---------------------
1878    
1879    1. A bit of extraneous text had somehow crept into the pcregrep documentation.
1880    
1881    2. If --disable-static was given, the building process failed when trying to
1882    build pcretest and pcregrep. (For some reason it was using libtool to compile
1883    them, which is not right, as they aren't part of the library.)
1884    
1885    
1886    Version 3.8 18-Dec-01
1887    ---------------------
1888    
1889    1. The experimental UTF-8 code was completely screwed up. It was packing the
1890    bytes in the wrong order. How dumb can you get?
1891    
1892    
1893    Version 3.7 29-Oct-01
1894    ---------------------
1895    
1896    1. In updating pcretest to check change 1 of version 3.6, I screwed up.
1897    This caused pcretest, when used on the test data, to segfault. Unfortunately,
1898    this didn't happen under Solaris 8, where I normally test things.
1899    
1900    2. The Makefile had to be changed to make it work on BSD systems, where 'make'
1901    doesn't seem to recognize that ./xxx and xxx are the same file. (This entry
1902    isn't in ChangeLog distributed with 3.7 because I forgot when I hastily made
1903    this fix an hour or so after the initial 3.7 release.)
1904    
1905    
1906    Version 3.6 23-Oct-01
1907    ---------------------
1908    
1909    1. Crashed with /(sens|respons)e and \1ibility/ and "sense and sensibility" if
1910    offsets passed as NULL with zero offset count.
1911    
1912    2. The config.guess and config.sub files had not been updated when I moved to
1913    the latest autoconf.
1914    
1915    
1916    Version 3.5 15-Aug-01
1917    ---------------------
1918    
1919    1. Added some missing #if !defined NOPOSIX conditionals in pcretest.c that
1920    had been forgotten.
1921    
1922    2. By using declared but undefined structures, we can avoid using "void"
1923    definitions in pcre.h while keeping the internal definitions of the structures
1924    private.
1925    
1926    3. The distribution is now built using autoconf 2.50 and libtool 1.4. From a
1927    user point of view, this means that both static and shared libraries are built
1928    by default, but this can be individually controlled. More of the work of
1929    handling this static/shared cases is now inside libtool instead of PCRE's make
1930    file.
1931    
1932    4. The pcretest utility is now installed along with pcregrep because it is
1933    useful for users (to test regexs) and by doing this, it automatically gets
1934    relinked by libtool. The documentation has been turned into a man page, so
1935    there are now .1, .txt, and .html versions in /doc.
1936    
1937    5. Upgrades to pcregrep:
1938       (i)   Added long-form option names like gnu grep.
1939       (ii)  Added --help to list all options with an explanatory phrase.
1940       (iii) Added -r, --recursive to recurse into sub-directories.
1941       (iv)  Added -f, --file to read patterns from a file.
1942    
1943    6. pcre_exec() was referring to its "code" argument before testing that
1944    argument for NULL (and giving an error if it was NULL).
1945    
1946    7. Upgraded Makefile.in to allow for compiling in a different directory from
1947    the source directory.
1948    
1949    8. Tiny buglet in pcretest: when pcre_fullinfo() was called to retrieve the
1950    options bits, the pointer it was passed was to an int instead of to an unsigned
1951    long int. This mattered only on 64-bit systems.
1952    
1953    9. Fixed typo (3.4/1) in pcre.h again. Sigh. I had changed pcre.h (which is
1954    generated) instead of pcre.in, which it its source. Also made the same change
1955    in several of the .c files.
1956    
1957    10. A new release of gcc defines printf() as a macro, which broke pcretest
1958    because it had an ifdef in the middle of a string argument for printf(). Fixed
1959    by using separate calls to printf().
1960    
1961    11. Added --enable-newline-is-cr and --enable-newline-is-lf to the configure
1962    script, to force use of CR or LF instead of \n in the source. On non-Unix
1963    systems, the value can be set in config.h.
1964    
1965    12. The limit of 200 on non-capturing parentheses is a _nesting_ limit, not an
1966    absolute limit. Changed the text of the error message to make this clear, and
1967    likewise updated the man page.
1968    
1969    13. The limit of 99 on the number of capturing subpatterns has been removed.
1970    The new limit is 65535, which I hope will not be a "real" limit.
1971    
1972    
1973    Version 3.4 22-Aug-00
1974    ---------------------
1975    
1976    1. Fixed typo in pcre.h: unsigned const char * changed to const unsigned char *.
1977    
1978    2. Diagnose condition (?(0) as an error instead of crashing on matching.
1979    
1980    
1981    Version 3.3 01-Aug-00
1982    ---------------------
1983    
1984    1. If an octal character was given, but the value was greater than \377, it
1985    was not getting masked to the least significant bits, as documented. This could
1986    lead to crashes in some systems.
1987    
1988    2. Perl 5.6 (if not earlier versions) accepts classes like [a-\d] and treats
1989    the hyphen as a literal. PCRE used to give an error; it now behaves like Perl.
1990    
1991    3. Added the functions pcre_free_substring() and pcre_free_substring_list().
1992    These just pass their arguments on to (pcre_free)(), but they are provided
1993    because some uses of PCRE bind it to non-C systems that can call its functions,
1994    but cannot call free() or pcre_free() directly.
1995    
1996    4. Add "make test" as a synonym for "make check". Corrected some comments in
1997    the Makefile.
1998    
1999    5. Add $(DESTDIR)/ in front of all the paths in the "install" target in the
2000    Makefile.
2001    
2002    6. Changed the name of pgrep to pcregrep, because Solaris has introduced a
2003    command called pgrep for grepping around the active processes.
2004    
2005    7. Added the beginnings of support for UTF-8 character strings.
2006    
2007    8. Arranged for the Makefile to pass over the settings of CC, CFLAGS, and
2008    RANLIB to ./ltconfig so that they are used by libtool. I think these are all
2009    the relevant ones. (AR is not passed because ./ltconfig does its own figuring
2010    out for the ar command.)
2011    
2012    
2013    Version 3.2 12-May-00
2014    ---------------------
2015    
2016    This is purely a bug fixing release.
2017    
2018    1. If the pattern /((Z)+|A)*/ was matched agained ZABCDEFG it matched Z instead
2019    of ZA. This was just one example of several cases that could provoke this bug,
2020    which was introduced by change 9 of version 2.00. The code for breaking
2021    infinite loops after an iteration that matches an empty string was't working
2022    correctly.
2023    
2024    2. The pcretest program was not imitating Perl correctly for the pattern /a*/g
2025    when matched against abbab (for example). After matching an empty string, it
2026    wasn't forcing anchoring when setting PCRE_NOTEMPTY for the next attempt; this
2027    caused it to match further down the string than it should.
2028    
2029    3. The code contained an inclusion of sys/types.h. It isn't clear why this
2030    was there because it doesn't seem to be needed, and it causes trouble on some
2031    systems, as it is not a Standard C header. It has been removed.
2032    
2033    4. Made 4 silly changes to the source to avoid stupid compiler warnings that
2034    were reported on the Macintosh. The changes were from
2035    
2036      while ((c = *(++ptr)) != 0 && c != '\n');
2037    to
2038      while ((c = *(++ptr)) != 0 && c != '\n') ;
2039    
2040    Totally extraordinary, but if that's what it takes...
2041    
2042    5. PCRE is being used in one environment where neither memmove() nor bcopy() is
2043    available. Added HAVE_BCOPY and an autoconf test for it; if neither
2044    HAVE_MEMMOVE nor HAVE_BCOPY is set, use a built-in emulation function which
2045    assumes the way PCRE uses memmove() (always moving upwards).
2046    
2047    6. PCRE is being used in one environment where strchr() is not available. There
2048    was only one use in pcre.c, and writing it out to avoid strchr() probably gives
2049    faster code anyway.
2050    
2051    
2052    Version 3.1 09-Feb-00
2053    ---------------------
2054    
2055    The only change in this release is the fixing of some bugs in Makefile.in for
2056    the "install" target:
2057    
2058    (1) It was failing to install pcreposix.h.
2059    
2060    (2) It was overwriting the pcre.3 man page with the pcreposix.3 man page.
2061    
2062    
2063    Version 3.0 01-Feb-00
2064    ---------------------
2065    
2066    1. Add support for the /+ modifier to perltest (to output $` like it does in
2067    pcretest).
2068    
2069    2. Add support for the /g modifier to perltest.
2070    
2071    3. Fix pcretest so that it behaves even more like Perl for /g when the pattern
2072    matches null strings.
2073    
2074    4. Fix perltest so that it doesn't do unwanted things when fed an empty
2075    pattern. Perl treats empty patterns specially - it reuses the most recent
2076    pattern, which is not what we want. Replace // by /(?#)/ in order to avoid this
2077    effect.
2078    
2079    5. The POSIX interface was broken in that it was just handing over the POSIX
2080    captured string vector to pcre_exec(), but (since release 2.00) PCRE has
2081    required a bigger vector, with some working space on the end. This means that
2082    the POSIX wrapper now has to get and free some memory, and copy the results.
2083    
2084    6. Added some simple autoconf support, placing the test data and the
2085    documentation in separate directories, re-organizing some of the
2086    information files, and making it build pcre-config (a GNU standard). Also added
2087    libtool support for building PCRE as a shared library, which is now the
2088    default.
2089    
2090    7. Got rid of the leading zero in the definition of PCRE_MINOR because 08 and
2091    09 are not valid octal constants. Single digits will be used for minor values
2092    less than 10.
2093    
2094    8. Defined REG_EXTENDED and REG_NOSUB as zero in the POSIX header, so that
2095    existing programs that set these in the POSIX interface can use PCRE without
2096    modification.
2097    
2098    9. Added a new function, pcre_fullinfo() with an extensible interface. It can
2099    return all that pcre_info() returns, plus additional data. The pcre_info()
2100    function is retained for compatibility, but is considered to be obsolete.
2101    
2102    10. Added experimental recursion feature (?R) to handle one common case that
2103    Perl 5.6 will be able to do with (?p{...}).
2104    
2105    11. Added support for POSIX character classes like [:alpha:], which Perl is
2106    adopting.
2107    
2108    
2109    Version 2.08 31-Aug-99
2110    ----------------------
2111    
2112    1. When startoffset was not zero and the pattern began with ".*", PCRE was not
2113    trying to match at the startoffset position, but instead was moving forward to
2114    the next newline as if a previous match had failed.
2115    
2116    2. pcretest was not making use of PCRE_NOTEMPTY when repeating for /g and /G,
2117    and could get into a loop if a null string was matched other than at the start
2118    of the subject.
2119    
2120    3. Added definitions of PCRE_MAJOR and PCRE_MINOR to pcre.h so the version can
2121    be distinguished at compile time, and for completeness also added PCRE_DATE.
2122    
2123    5. Added Paul Sokolovsky's minor changes to make it easy to compile a Win32 DLL
2124    in GnuWin32 environments.
2125    
2126    
2127    Version 2.07 29-Jul-99
2128    ----------------------
2129    
2130    1. The documentation is now supplied in plain text form and HTML as well as in
2131    the form of man page sources.
2132    
2133    2. C++ compilers don't like assigning (void *) values to other pointer types.
2134    In particular this affects malloc(). Although there is no problem in Standard
2135    C, I've put in casts to keep C++ compilers happy.
2136    
2137    3. Typo on pcretest.c; a cast of (unsigned char *) in the POSIX regexec() call
2138    should be (const char *).
2139    
2140    4. If NOPOSIX is defined, pcretest.c compiles without POSIX support. This may
2141    be useful for non-Unix systems who don't want to bother with the POSIX stuff.
2142    However, I haven't made this a standard facility. The documentation doesn't
2143    mention it, and the Makefile doesn't support it.
2144    
2145    5. The Makefile now contains an "install" target, with editable destinations at
2146    the top of the file. The pcretest program is not installed.
2147    
2148    6. pgrep -V now gives the PCRE version number and date.
2149    
2150    7. Fixed bug: a zero repetition after a literal string (e.g. /abcde{0}/) was
2151    causing the entire string to be ignored, instead of just the last character.
2152    
2153    8. If a pattern like /"([^\\"]+|\\.)*"/ is applied in the normal way to a
2154    non-matching string, it can take a very, very long time, even for strings of
2155    quite modest length, because of the nested recursion. PCRE now does better in
2156    some of these cases. It does this by remembering the last required literal
2157    character in the pattern, and pre-searching the subject to ensure it is present
2158    before running the real match. In other words, it applies a heuristic to detect
2159    some types of certain failure quickly, and in the above example, if presented
2160    with a string that has no trailing " it gives "no match" very quickly.
2161    
2162    9. A new runtime option PCRE_NOTEMPTY causes null string matches to be ignored;
2163    other alternatives are tried instead.
2164    
2165    
2166    Version 2.06 09-Jun-99
2167    ----------------------
2168    
2169    1. Change pcretest's output for amount of store used to show just the code
2170    space, because the remainder (the data block) varies in size between 32-bit and
2171    64-bit systems.
2172    
2173    2. Added an extra argument to pcre_exec() to supply an offset in the subject to
2174    start matching at. This allows lookbehinds to work when searching for multiple
2175    occurrences in a string.
2176    
2177    3. Added additional options to pcretest for testing multiple occurrences:
2178    
2179       /+   outputs the rest of the string that follows a match
2180       /g   loops for multiple occurrences, using the new startoffset argument
2181       /G   loops for multiple occurrences by passing an incremented pointer
2182    
2183    4. PCRE wasn't doing the "first character" optimization for patterns starting
2184    with \b or \B, though it was doing it for other lookbehind assertions. That is,
2185    it wasn't noticing that a match for a pattern such as /\bxyz/ has to start with
2186    the letter 'x'. On long subject strings, this gives a significant speed-up.
2187    
2188    
2189    Version 2.05 21-Apr-99
2190    ----------------------
2191    
2192    1. Changed the type of magic_number from int to long int so that it works
2193    properly on 16-bit systems.
2194    
2195    2. Fixed a bug which caused patterns starting with .* not to work correctly
2196    when the subject string contained newline characters. PCRE was assuming
2197    anchoring for such patterns in all cases, which is not correct because .* will
2198    not pass a newline unless PCRE_DOTALL is set. It now assumes anchoring only if
2199    DOTALL is set at top level; otherwise it knows that patterns starting with .*
2200    must be retried after every newline in the subject.
2201    
2202    
2203    Version 2.04 18-Feb-99
2204    ----------------------
2205    
2206    1. For parenthesized subpatterns with repeats whose minimum was zero, the
2207    computation of the store needed to hold the pattern was incorrect (too large).
2208    If such patterns were nested a few deep, this could multiply and become a real
2209    problem.
2210    
2211    2. Added /M option to pcretest to show the memory requirement of a specific
2212    pattern. Made -m a synonym of -s (which does this globally) for compatibility.
2213    
2214    3. Subpatterns of the form (regex){n,m} (i.e. limited maximum) were being
2215    compiled in such a way that the backtracking after subsequent failure was
2216    pessimal. Something like (a){0,3} was compiled as (a)?(a)?(a)? instead of
2217    ((a)((a)(a)?)?)? with disastrous performance if the maximum was of any size.
2218    
2219    
2220    Version 2.03 02-Feb-99
2221    ----------------------
2222    
2223    1. Fixed typo and small mistake in man page.
2224    
2225    2. Added 4th condition (GPL supersedes if conflict) and created separate
2226    LICENCE file containing the conditions.
2227    
2228    3. Updated pcretest so that patterns such as /abc\/def/ work like they do in
2229    Perl, that is the internal \ allows the delimiter to be included in the
2230    pattern. Locked out the use of \ as a delimiter. If \ immediately follows
2231    the final delimiter, add \ to the end of the pattern (to test the error).
2232    
2233    4. Added the convenience functions for extracting substrings after a successful
2234    match. Updated pcretest to make it able to test these functions.
2235    
2236    
2237    Version 2.02 14-Jan-99
2238    ----------------------
2239    
2240    1. Initialized the working variables associated with each extraction so that
2241    their saving and restoring doesn't refer to uninitialized store.
2242    
2243    2. Put dummy code into study.c in order to trick the optimizer of the IBM C
2244    compiler for OS/2 into generating correct code. Apparently IBM isn't going to
2245    fix the problem.
2246    
2247    3. Pcretest: the timing code wasn't using LOOPREPEAT for timing execution
2248    calls, and wasn't printing the correct value for compiling calls. Increased the
2249    default value of LOOPREPEAT, and the number of significant figures in the
2250    times.
2251    
2252    4. Changed "/bin/rm" in the Makefile to "-rm" so it works on Windows NT.
2253    
2254    5. Renamed "deftables" as "dftables" to get it down to 8 characters, to avoid
2255    a building problem on Windows NT with a FAT file system.
2256    
2257    
2258    Version 2.01 21-Oct-98
2259    ----------------------
2260    
2261    1. Changed the API for pcre_compile() to allow for the provision of a pointer
2262    to character tables built by pcre_maketables() in the current locale. If NULL
2263    is passed, the default tables are used.
2264    
2265    
2266    Version 2.00 24-Sep-98
2267    ----------------------
2268    
2269    1. Since the (>?) facility is in Perl 5.005, don't require PCRE_EXTRA to enable
2270    it any more.
2271    
2272    2. Allow quantification of (?>) groups, and make it work correctly.
2273    
2274    3. The first character computation wasn't working for (?>) groups.
2275    
2276    4. Correct the implementation of \Z (it is permitted to match on the \n at the
2277    end of the subject) and add 5.005's \z, which really does match only at the
2278    very end of the subject.
2279    
2280    5. Remove the \X "cut" facility; Perl doesn't have it, and (?> is neater.
2281    
2282    6. Remove the ability to specify CASELESS, MULTILINE, DOTALL, and
2283    DOLLAR_END_ONLY at runtime, to make it possible to implement the Perl 5.005
2284    localized options. All options to pcre_study() were also removed.
2285    
2286    7. Add other new features from 5.005:
2287    
2288       $(?<=           positive lookbehind
2289       $(?<!           negative lookbehind
2290       (?imsx-imsx)    added the unsetting capability
2291                       such a setting is global if at outer level; local otherwise
2292       (?imsx-imsx:)   non-capturing groups with option setting
2293       (?(cond)re|re)  conditional pattern matching
2294    
2295       A backreference to itself in a repeated group matches the previous
2296       captured string.
2297    
2298    8. General tidying up of studying (both automatic and via "study")
2299    consequential on the addition of new assertions.
2300    
2301    9. As in 5.005, unlimited repeated groups that could match an empty substring
2302    are no longer faulted at compile time. Instead, the loop is forcibly broken at
2303    runtime if any iteration does actually match an empty substring.
2304    
2305    10. Include the RunTest script in the distribution.
2306    
2307    11. Added tests from the Perl 5.005_02 distribution. This showed up a few
2308    discrepancies, some of which were old and were also with respect to 5.004. They
2309    have now been fixed.
2310    
2311    
2312    Version 1.09 28-Apr-98
2313    ----------------------
2314    
2315    1. A negated single character class followed by a quantifier with a minimum
2316    value of one (e.g.  [^x]{1,6}  ) was not compiled correctly. This could lead to
2317    program crashes, or just wrong answers. This did not apply to negated classes
2318    containing more than one character, or to minima other than one.
2319    
2320    
2321  Version 1.08 27-Mar-98  Version 1.08 27-Mar-98
2322  ----------------------  ----------------------

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