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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
4    Version 7.1 12-Mar-07
5    ---------------------
7     1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
8        that is more "standard", making use of automake and other Autotools. There
9        is some re-arrangement of the files and adjustment of comments consequent
10        on this.
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.
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.
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).
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
36        makevp_c.txt, makevp_l.txt, and pcregexp.pas.
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.
42     7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
43        that is needed.
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.
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.
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.
63    10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
65        (a) It was defining its arguments as char * instead of void *.
67        (b) It was assuming that all moves were upwards in memory; this was true
68            a long time ago when I wrote it, but is no longer the case.
70        The emulated memove() is provided for those environments that have neither
71        memmove() nor bcopy(). I didn't think anyone used it these days, but that
72        is clearly not the case, as these two bugs were recently reported.
74    11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
75        and Detrail to create the HTML documentation, the .txt form of the man
76        pages, and it removes trailing spaces from listed files. It also creates
77        pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
78        case, it wraps all the #defines with #ifndefs. This script should be run
79        before "make dist".
81    12. Fixed two fairly obscure bugs concerned with quantified caseless matching
82        with Unicode property support.
84        (a) For a maximizing quantifier, if the two different cases of the
85            character were of different lengths in their UTF-8 codings (there are
86            some cases like this - I found 11), and the matching function had to
87            back up over a mixture of the two cases, it incorrectly assumed they
88            were both the same length.
90        (b) When PCRE was configured to use the heap rather than the stack for
91            recursion during matching, it was not correctly preserving the data for
92            the other case of a UTF-8 character when checking ahead for a match
93            while processing a minimizing repeat. If the check also involved
94            matching a wide character, but failed, corruption could cause an
95            erroneous result when trying to check for a repeat of the original
96            character.
98    13. Some tidying changes to the testing mechanism:
100        (a) The RunTest script now detects the internal link size and whether there
101            is UTF-8 and UCP support by running ./pcretest -C instead of relying on
102            values substituted by "configure". (The RunGrepTest script already did
103            this for UTF-8.) The configure.ac script no longer substitutes the
104            relevant variables.
106        (b) The debugging options /B and /D in pcretest show the compiled bytecode
107            with length and offset values. This means that the output is different
108            for different internal link sizes. Test 2 is skipped for link sizes
109            other than 2 because of this, bypassing the problem. Unfortunately,
110            there was also a test in test 3 (the locale tests) that used /B and
111            failed for link sizes other than 2. Rather than cut the whole test out,
112            I have added a new /Z option to pcretest that replaces the length and
113            offset values with spaces. This is now used to make test 3 independent
114            of link size. (Test 2 will be tidied up later.)
116    14. If erroroffset was passed as NULL to pcre_compile, it provoked a
117        segmentation fault instead of returning the appropriate error message.
119    15. In multiline mode when the newline sequence was set to "any", the pattern
120        ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
121        This doesn't seem right; it now treats the CRLF combination as the line
122        ending, and so does not match in that case. It's only a pattern such as ^$
123        that would hit this one: something like ^ABC$ would have failed after \r
124        and then tried again after \r\n.
126    16. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
127        in an attempt to make files that differ only in their line terminators
128        compare equal. This works on Linux.
130    17. Under certain error circumstances pcregrep might try to free random memory
131        as it exited. This is now fixed, thanks to valgrind.
133    19. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
134        "abc\r\n\r\n", it found an unwanted second match after the second \r. This
135        was because its rules for how to advance for /g after matching an empty
136        string at the end of a line did not allow for this case. They now check for
137        it specially.
139    20. pcretest is supposed to handle patterns and data of any length, by
140        extending its buffers when necessary. It was getting this wrong when the
141        buffer for a data line had to be extended.
143    21. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or
144        CRLF as a newline sequence.
146    22. Code for handling Unicode properties in pcre_dfa_exec() wasn't being cut
147        out by #ifdef SUPPORT_UCP. This did no harm, as it could never be used, but
148        I have nevertheless tidied it up.
150    23. Added some casts to kill warnings from HP-UX ia64 compiler.
153    Version 7.0 19-Dec-06
154    ---------------------
156     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
157        moving to gcc 4.1.1.
159     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
160        sys/time.h, which is documented as needed for this function. It doesn't
161        seem to matter on Linux, but it showed up on some releases of OS X.
163     3. It seems that there are systems where bytes whose values are greater than
164        127 match isprint() in the "C" locale. The "C" locale should be the
165        default when a C program starts up. In most systems, only ASCII printing
166        characters match isprint(). This difference caused the output from pcretest
167        to vary, making some of the tests fail. I have changed pcretest so that:
169        (a) When it is outputting text in the compiled version of a pattern, bytes
170            other than 32-126 are always shown as hex escapes.
172        (b) When it is outputting text that is a matched part of a subject string,
173            it does the same, unless a different locale has been set for the match
174            (using the /L modifier). In this case, it uses isprint() to decide.
176     4. Fixed a major bug that caused incorrect computation of the amount of memory
177        required for a compiled pattern when options that changed within the
178        pattern affected the logic of the preliminary scan that determines the
179        length. The relevant options are -x, and -i in UTF-8 mode. The result was
180        that the computed length was too small. The symptoms of this bug were
181        either the PCRE error "internal error: code overflow" from pcre_compile(),
182        or a glibc crash with a message such as "pcretest: free(): invalid next
183        size (fast)". Examples of patterns that provoked this bug (shown in
184        pcretest format) are:
186          /(?-x: )/x
187          /(?x)(?-x: \s*#\s*)/
188          /((?i)[\x{c0}])/8
189          /(?i:[\x{c0}])/8
191        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
192        is now done differently.
194     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
195        wrapper classes; (b) implement a new function in the C++ scanner that is
196        more efficient than the old way of doing things because it avoids levels of
197        recursion in the regex matching; (c) add a paragraph to the documentation
198        for the FullMatch() function.
200     6. The escape sequence \n was being treated as whatever was defined as
201        "newline". Not only was this contrary to the documentation, which states
202        that \n is character 10 (hex 0A), but it also went horribly wrong when
203        "newline" was defined as CRLF. This has been fixed.
205     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
206        was being set to -1 for the "end of line" case (supposedly a value that no
207        character can have). Though this value is never used (the check for end of
208        line is "zero bytes in current character"), it caused compiler complaints.
209        I've changed it to 0xffffffff.
211     8. In pcre_version.c, the version string was being built by a sequence of
212        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
213        string (as it is for production releases) called a macro with an empty
214        argument. The C standard says the result of this is undefined. The gcc
215        compiler treats it as an empty string (which was what was wanted) but it is
216        reported that Visual C gives an error. The source has been hacked around to
217        avoid this problem.
219     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
220        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
221        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
222        of them did).
224    10. Originally, pcretest opened its input and output without "b"; then I was
225        told that "b" was needed in some environments, so it was added for release
226        5.0 to both the input and output. (It makes no difference on Unix-like
227        systems.) Later I was told that it is wrong for the input on Windows. I've
228        now abstracted the modes into two macros, to make it easier to fiddle with
229        them, and removed "b" from the input mode under Windows.
231    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
233    12. Added -help and --help to pcretest as an official way of being reminded
234        of the options.
236    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
237        and pcrecpp.cc because they annoy compilers at high warning levels.
239    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
241    15. Fixed an occurrence of == in configure.ac that should have been = (shell
242        scripts are not C programs :-) and which was not noticed because it works
243        on Linux.
245    16. pcretest is supposed to handle any length of pattern and data line (as one
246        line or as a continued sequence of lines) by extending its input buffer if
247        necessary. This feature was broken for very long pattern lines, leading to
248        a string of junk being passed to pcre_compile() if the pattern was longer
249        than about 50K.
251    17. I have done a major re-factoring of the way pcre_compile() computes the
252        amount of memory needed for a compiled pattern. Previously, there was code
253        that made a preliminary scan of the pattern in order to do this. That was
254        OK when PCRE was new, but as the facilities have expanded, it has become
255        harder and harder to keep it in step with the real compile phase, and there
256        have been a number of bugs (see for example, 4 above). I have now found a
257        cunning way of running the real compile function in a "fake" mode that
258        enables it to compute how much memory it would need, while actually only
259        ever using a few hundred bytes of working memory and without too many
260        tests of the mode. This should make future maintenance and development
261        easier. A side effect of this work is that the limit of 200 on the nesting
262        depth of parentheses has been removed (though this was never a serious
263        limitation, I suspect). However, there is a downside: pcre_compile() now
264        runs more slowly than before (30% or more, depending on the pattern). I
265        hope this isn't a big issue. There is no effect on runtime performance.
267    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
268        newline (only possible for the last line of a file) and it was a
269        pattern that set a locale (followed by /Lsomething), pcretest crashed.
271    19. Added additional timing features to pcretest. (1) The -tm option now times
272        matching only, not compiling. (2) Both -t and -tm can be followed, as a
273        separate command line item, by a number that specifies the number of
274        repeats to use when timing. The default is 50000; this gives better
275        precision, but takes uncomfortably long for very large patterns.
277    20. Extended pcre_study() to be more clever in cases where a branch of a
278        subpattern has no definite first character. For example, (a*|b*)[cd] would
279        previously give no result from pcre_study(). Now it recognizes that the
280        first character must be a, b, c, or d.
282    21. There was an incorrect error "recursive call could loop indefinitely" if
283        a subpattern (or the entire pattern) that was being tested for matching an
284        empty string contained only one non-empty item after a nested subpattern.
285        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
286        incorrectly, because the \d was being skipped in the check.
288    22. The pcretest program now has a new pattern option /B and a command line
289        option -b, which is equivalent to adding /B to every pattern. This causes
290        it to show the compiled bytecode, without the additional information that
291        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
292        is the same as /B/I).
294    23. A new optimization is now able automatically to treat some sequences such
295        as a*b as a*+b. More specifically, if something simple (such as a character
296        or a simple class like \d) has an unlimited quantifier, and is followed by
297        something that cannot possibly match the quantified thing, the quantifier
298        is automatically "possessified".
300    24. A recursive reference to a subpattern whose number was greater than 39
301        went wrong under certain circumstances in UTF-8 mode. This bug could also
302        have affected the operation of pcre_study().
304    25. Realized that a little bit of performance could be had by replacing
305        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
307    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
309    27. Possessive quantifiers such as a++ were previously implemented by turning
310        them into atomic groups such as ($>a+). Now they have their own opcodes,
311        which improves performance. This includes the automatically created ones
312        from 23 above.
314    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
315        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
316        the first matched character to be a colon. This applied both to named and
317        numbered groups.
319    29. The ucpinternal.h header file was missing its idempotency #ifdef.
321    30. I was sent a "project" file called libpcre.a.dev which I understand makes
322        building PCRE on Windows easier, so I have included it in the distribution.
324    31. There is now a check in pcretest against a ridiculously large number being
325        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
326        loop, the loop is abandoned.
328    32. Forward references to subpatterns in conditions such as (?(2)...) where
329        subpattern 2 is defined later cause pcre_compile() to search forwards in
330        the pattern for the relevant set of parentheses. This search went wrong
331        when there were unescaped parentheses in a character class, parentheses
332        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
334    33. "Subroutine" calls and backreferences were previously restricted to
335        referencing subpatterns earlier in the regex. This restriction has now
336        been removed.
338    34. Added a number of extra features that are going to be in Perl 5.10. On the
339        whole, these are just syntactic alternatives for features that PCRE had
340        previously implemented using the Python syntax or my own invention. The
341        other formats are all retained for compatibility.
343        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
344            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
345            also .NET compatible.
347        (b) A recursion or subroutine call to a named group can now be defined as
348            (?&name) as well as (?P>name).
350        (c) A backreference to a named group can now be defined as \k<name> or
351            \k'name' as well as (?P=name). The new forms, as well as being in Perl
352            5.10, are also .NET compatible.
354        (d) A conditional reference to a named group can now use the syntax
355            (?(<name>) or (?('name') as well as (?(name).
357        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
358            groups (named and numbered) that are never evaluated inline, but can be
359            called as "subroutines" from elsewhere. In effect, the DEFINE condition
360            is always false. There may be only one alternative in such a group.
362        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
363            as the simple (?(R). The condition is true only if the most recent
364            recursion is that of the given number or name. It does not search out
365            through the entire recursion stack.
367        (g) The escape \gN or \g{N} has been added, where N is a positive or
368            negative number, specifying an absolute or relative reference.
370    35. Tidied to get rid of some further signed/unsigned compiler warnings and
371        some "unreachable code" warnings.
373    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
374        things, this adds five new scripts.
376    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
377        There were also incompatibilities regarding the handling of \Q..\E inside
378        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
379        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
381    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
382        matches an empty string, and forcibly breaks the loop. There were bugs in
383        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
384        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
385        separate and independent bugs (that affected different cases) have been
386        fixed.
388    39. Refactored the code to abolish the use of different opcodes for small
389        capturing bracket numbers. This is a tidy that I avoided doing when I
390        removed the limit on the number of capturing brackets for 3.5 back in 2001.
391        The new approach is not only tidier, it makes it possible to reduce the
392        memory needed to fix the previous bug (38).
394    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
395        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
396        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
397        mode.
399    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
400        report.
402    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
403        copy construction and assignment in the C++ wrapper.
405    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
406        couple of bugs that could have given wrong results in the "--newline=crlf"
407        case.
409    44. Added a number of casts and did some reorganization of signed/unsigned int
410        variables following suggestions from Dair Grant. Also renamed the variable
411        "this" as "item" because it is a C++ keyword.
413    45. Arranged for dftables to add
415          #include "pcre_internal.h"
417        to pcre_chartables.c because without it, gcc 4.x may remove the array
418        definition from the final binary if PCRE is built into a static library and
419        dead code stripping is activated.
421    46. For an unanchored pattern, if a match attempt fails at the start of a
422        newline sequence, and the newline setting is CRLF or ANY, and the next two
423        characters are CRLF, advance by two characters instead of one.
426    Version 6.7 04-Jul-06
427    ---------------------
429     1. In order to handle tests when input lines are enormously long, pcretest has
430        been re-factored so that it automatically extends its buffers when
431        necessary. The code is crude, but this _is_ just a test program. The
432        default size has been increased from 32K to 50K.
434     2. The code in pcre_study() was using the value of the re argument before
435        testing it for NULL. (Of course, in any sensible call of the function, it
436        won't be NULL.)
438     3. The memmove() emulation function in pcre_internal.h, which is used on
439        systems that lack both memmove() and bcopy() - that is, hardly ever -
440        was missing a "static" storage class specifier.
442     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
443        containing an extended class (one that cannot be represented by a bitmap
444        because it contains high-valued characters or Unicode property items, e.g.
445        [\pZ]). Almost always one would set UTF-8 mode when processing such a
446        pattern, but PCRE should not loop if you do not (it no longer does).
447        [Detail: two cases were found: (a) a repeated subpattern containing an
448        extended class; (b) a recursive reference to a subpattern that followed a
449        previous extended class. It wasn't skipping over the extended class
450        correctly when UTF-8 mode was not set.]
452     5. A negated single-character class was not being recognized as fixed-length
453        in lookbehind assertions such as (?<=[^f]), leading to an incorrect
454        compile error "lookbehind assertion is not fixed length".
456     6. The RunPerlTest auxiliary script was showing an unexpected difference
457        between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
458        write a Perl script that can interpret lines of an input file either as
459        byte characters or as UTF-8, which is what "perltest" was being required to
460        do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
461        can't do is switch easily at run time between having the "use utf8;" pragma
462        or not. In the end, I fudged it by using the RunPerlTest script to insert
463        "use utf8;" explicitly for the UTF-8 tests.
465     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
466        the end of the subject string, contrary to the documentation and to what
467        Perl does. This was true of both matching functions. Now it matches only at
468        the start of the subject and immediately after *internal* newlines.
470     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
471        a pointer to an int instead of a pointer to an unsigned long int. This
472        caused problems on 64-bit systems.
474     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
475        instance of the 'standard' template library not being so standard".
477    10. There was no check on the number of named subpatterns nor the maximum
478        length of a subpattern name. The product of these values is used to compute
479        the size of the memory block for a compiled pattern. By supplying a very
480        long subpattern name and a large number of named subpatterns, the size
481        computation could be caused to overflow. This is now prevented by limiting
482        the length of names to 32 characters, and the number of named subpatterns
483        to 10,000.
485    11. Subpatterns that are repeated with specific counts have to be replicated in
486        the compiled pattern. The size of memory for this was computed from the
487        length of the subpattern and the repeat count. The latter is limited to
488        65535, but there was no limit on the former, meaning that integer overflow
489        could in principle occur. The compiled length of a repeated subpattern is
490        now limited to 30,000 bytes in order to prevent this.
492    12. Added the optional facility to have named substrings with the same name.
494    13. Added the ability to use a named substring as a condition, using the
495        Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
496        are numbers (not recommended). Forward references are permitted.
498    14. Added forward references in named backreferences (if you see what I mean).
500    15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
501        pattern could run off the end of the subject. For example, the pattern
502        "(?s)(.{1,5})"8 did this with the subject "ab".
504    16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
505        PCRE_CASELESS was set when matching characters that were quantified with ?
506        or *.
508    17. A character class other than a single negated character that had a minimum
509        but no maximum quantifier - for example [ab]{6,} - was not handled
510        correctly by pce_dfa_exec(). It would match only one character.
512    18. A valid (though odd) pattern that looked like a POSIX character
513        class but used an invalid character after [ (for example [[,abc,]]) caused
514        pcre_compile() to give the error "Failed: internal error: code overflow" or
515        in some cases to crash with a glibc free() error. This could even happen if
516        the pattern terminated after [[ but there just happened to be a sequence of
517        letters, a binary zero, and a closing ] in the memory that followed.
519    19. Perl's treatment of octal escapes in the range \400 to \777 has changed
520        over the years. Originally (before any Unicode support), just the bottom 8
521        bits were taken. Thus, for example, \500 really meant \100. Nowadays the
522        output from "man perlunicode" includes this:
524          The regular expression compiler produces polymorphic opcodes.  That
525          is, the pattern adapts to the data and automatically switches to
526          the Unicode character scheme when presented with Unicode data--or
527          instead uses a traditional byte scheme when presented with byte
528          data.
530        Sadly, a wide octal escape does not cause a switch, and in a string with
531        no other multibyte characters, these octal escapes are treated as before.
532        Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
533        /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
534        Unicode string.
536        I have not perpetrated such confusion in PCRE. Up till now, it took just
537        the bottom 8 bits, as in old Perl. I have now made octal escapes with
538        values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
539        translate to the appropriate multibyte character.
541    29. Applied some refactoring to reduce the number of warnings from Microsoft
542        and Borland compilers. This has included removing the fudge introduced
543        seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
544        a warning about an unused variable.
546    21. PCRE has not included VT (character 0x0b) in the set of whitespace
547        characters since release 4.0, because Perl (from release 5.004) does not.
548        [Or at least, is documented not to: some releases seem to be in conflict
549        with the documentation.] However, when a pattern was studied with
550        pcre_study() and all its branches started with \s, PCRE still included VT
551        as a possible starting character. Of course, this did no harm; it just
552        caused an unnecessary match attempt.
554    22. Removed a now-redundant internal flag bit that recorded the fact that case
555        dependency changed within the pattern. This was once needed for "required
556        byte" processing, but is no longer used. This recovers a now-scarce options
557        bit. Also moved the least significant internal flag bit to the most-
558        significant bit of the word, which was not previously used (hangover from
559        the days when it was an int rather than a uint) to free up another bit for
560        the future.
562    23. Added support for CRLF line endings as well as CR and LF. As well as the
563        default being selectable at build time, it can now be changed at runtime
564        via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
565        specify that it is scanning data with non-default line endings.
567    24. Changed the definition of CXXLINK to make it agree with the definition of
568        LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
570    25. Applied Ian Taylor's patches to avoid using another stack frame for tail
571        recursions. This makes a big different to stack usage for some patterns.
573    26. If a subpattern containing a named recursion or subroutine reference such
574        as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
575        the space required for the compiled pattern went wrong and gave too small a
576        value. Depending on the environment, this could lead to "Failed: internal
577        error: code overflow at offset 49" or "glibc detected double free or
578        corruption" errors.
580    27. Applied patches from Google (a) to support the new newline modes and (b) to
581        advance over multibyte UTF-8 characters in GlobalReplace.
583    28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
584        difference for some implementation of PCRE in some Windows version.
586    29. Added some extra testing facilities to pcretest:
588        \q<number>   in a data line sets the "match limit" value
589        \Q<number>   in a data line sets the "match recursion limt" value
590        -S <number>  sets the stack size, where <number> is in megabytes
592        The -S option isn't available for Windows.
595    Version 6.6 06-Feb-06
596    ---------------------
598     1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
599        in pcreposix.h. I have copied the definition from pcre.h.
601     2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
602        because pcre.h is no longer a built file.
604     3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
605        not normally included in the compiled code.
608    Version 6.5 01-Feb-06
609    ---------------------
611     1. When using the partial match feature with pcre_dfa_exec(), it was not
612        anchoring the second and subsequent partial matches at the new starting
613        point. This could lead to incorrect results. For example, with the pattern
614        /1234/, partially matching against "123" and then "a4" gave a match.
616     2. Changes to pcregrep:
618        (a) All non-match returns from pcre_exec() were being treated as failures
619            to match the line. Now, unless the error is PCRE_ERROR_NOMATCH, an
620            error message is output. Some extra information is given for the
621            PCRE_ERROR_MATCHLIMIT and PCRE_ERROR_RECURSIONLIMIT errors, which are
622            probably the only errors that are likely to be caused by users (by
623            specifying a regex that has nested indefinite repeats, for instance).
624            If there are more than 20 of these errors, pcregrep is abandoned.
626        (b) A binary zero was treated as data while matching, but terminated the
627            output line if it was written out. This has been fixed: binary zeroes
628            are now no different to any other data bytes.
630        (c) Whichever of the LC_ALL or LC_CTYPE environment variables is set is
631            used to set a locale for matching. The --locale=xxxx long option has
632            been added (no short equivalent) to specify a locale explicitly on the
633            pcregrep command, overriding the environment variables.
635        (d) When -B was used with -n, some line numbers in the output were one less
636            than they should have been.
638        (e) Added the -o (--only-matching) option.
640        (f) If -A or -C was used with -c (count only), some lines of context were
641            accidentally printed for the final match.
643        (g) Added the -H (--with-filename) option.
645        (h) The combination of options -rh failed to suppress file names for files
646            that were found from directory arguments.
648        (i) Added the -D (--devices) and -d (--directories) options.
650        (j) Added the -F (--fixed-strings) option.
652        (k) Allow "-" to be used as a file name for -f as well as for a data file.
654        (l) Added the --colo(u)r option.
656        (m) Added Jeffrey Friedl's -S testing option, but within #ifdefs so that it
657            is not present by default.
659     3. A nasty bug was discovered in the handling of recursive patterns, that is,
660        items such as (?R) or (?1), when the recursion could match a number of
661        alternatives. If it matched one of the alternatives, but subsequently,
662        outside the recursion, there was a failure, the code tried to back up into
663        the recursion. However, because of the way PCRE is implemented, this is not
664        possible, and the result was an incorrect result from the match.
666        In order to prevent this happening, the specification of recursion has
667        been changed so that all such subpatterns are automatically treated as
668        atomic groups. Thus, for example, (?R) is treated as if it were (?>(?R)).
670     4. I had overlooked the fact that, in some locales, there are characters for
671        which isalpha() is true but neither isupper() nor islower() are true. In
672        the fr_FR locale, for instance, the \xAA and \xBA characters (ordmasculine
673        and ordfeminine) are like this. This affected the treatment of \w and \W
674        when they appeared in character classes, but not when they appeared outside
675        a character class. The bit map for "word" characters is now created
676        separately from the results of isalnum() instead of just taking it from the
677        upper, lower, and digit maps. (Plus the underscore character, of course.)
679     5. The above bug also affected the handling of POSIX character classes such as
680        [[:alpha:]] and [[:alnum:]]. These do not have their own bit maps in PCRE's
681        permanent tables. Instead, the bit maps for such a class were previously
682        created as the appropriate unions of the upper, lower, and digit bitmaps.
683        Now they are created by subtraction from the [[:word:]] class, which has
684        its own bitmap.
686     6. The [[:blank:]] character class matches horizontal, but not vertical space.
687        It is created by subtracting the vertical space characters (\x09, \x0a,
688        \x0b, \x0c) from the [[:space:]] bitmap. Previously, however, the
689        subtraction was done in the overall bitmap for a character class, meaning
690        that a class such as [\x0c[:blank:]] was incorrect because \x0c would not
691        be recognized. This bug has been fixed.
693     7. Patches from the folks at Google:
695          (a) pcrecpp.cc: "to handle a corner case that may or may not happen in
696          real life, but is still worth protecting against".
698          (b) pcrecpp.cc: "corrects a bug when negative radixes are used with
699          regular expressions".
701          (c) pcre_scanner.cc: avoid use of std::count() because not all systems
702          have it.
704          (d) Split off pcrecpparg.h from pcrecpp.h and had the former built by
705          "configure" and the latter not, in order to fix a problem somebody had
706          with compiling the Arg class on HP-UX.
708          (e) Improve the error-handling of the C++ wrapper a little bit.
710          (f) New tests for checking recursion limiting.
712     8. The pcre_memmove() function, which is used only if the environment does not
713        have a standard memmove() function (and is therefore rarely compiled),
714        contained two bugs: (a) use of int instead of size_t, and (b) it was not
715        returning a result (though PCRE never actually uses the result).
717     9. In the POSIX regexec() interface, if nmatch is specified as a ridiculously
718        large number - greater than INT_MAX/(3*sizeof(int)) - REG_ESPACE is
719        returned instead of calling malloc() with an overflowing number that would
720        most likely cause subsequent chaos.
722    10. The debugging option of pcretest was not showing the NO_AUTO_CAPTURE flag.
724    11. The POSIX flag REG_NOSUB is now supported. When a pattern that was compiled
725        with this option is matched, the nmatch and pmatch options of regexec() are
726        ignored.
728    12. Added REG_UTF8 to the POSIX interface. This is not defined by POSIX, but is
729        provided in case anyone wants to the the POSIX interface with UTF-8
730        strings.
732    13. Added CXXLDFLAGS to the Makefile parameters to provide settings only on the
733        C++ linking (needed for some HP-UX environments).
735    14. Avoid compiler warnings in get_ucpname() when compiled without UCP support
736        (unused parameter) and in the pcre_printint() function (omitted "default"
737        switch label when the default is to do nothing).
739    15. Added some code to make it possible, when PCRE is compiled as a C++
740        library, to replace subject pointers for pcre_exec() with a smart pointer
741        class, thus making it possible to process discontinuous strings.
743    16. The two macros PCRE_EXPORT and PCRE_DATA_SCOPE are confusing, and perform
744        much the same function. They were added by different people who were trying
745        to make PCRE easy to compile on non-Unix systems. It has been suggested
746        that PCRE_EXPORT be abolished now that there is more automatic apparatus
747        for compiling on Windows systems. I have therefore replaced it with
748        PCRE_DATA_SCOPE. This is set automatically for Windows; if not set it
749        defaults to "extern" for C or "extern C" for C++, which works fine on
750        Unix-like systems. It is now possible to override the value of PCRE_DATA_
751        SCOPE with something explicit in config.h. In addition:
753        (a) pcreposix.h still had just "extern" instead of either of these macros;
754            I have replaced it with PCRE_DATA_SCOPE.
756        (b) Functions such as _pcre_xclass(), which are internal to the library,
757            but external in the C sense, all had PCRE_EXPORT in their definitions.
758            This is apparently wrong for the Windows case, so I have removed it.
759            (It makes no difference on Unix-like systems.)
761    17. Added a new limit, MATCH_LIMIT_RECURSION, which limits the depth of nesting
762        of recursive calls to match(). This is different to MATCH_LIMIT because
763        that limits the total number of calls to match(), not all of which increase
764        the depth of recursion. Limiting the recursion depth limits the amount of
765        stack (or heap if NO_RECURSE is set) that is used. The default can be set
766        when PCRE is compiled, and changed at run time. A patch from Google adds
767        this functionality to the C++ interface.
769    18. Changes to the handling of Unicode character properties:
771        (a) Updated the table to Unicode 4.1.0.
773        (b) Recognize characters that are not in the table as "Cn" (undefined).
775        (c) I revised the way the table is implemented to a much improved format
776            which includes recognition of ranges. It now supports the ranges that
777            are defined in UnicodeData.txt, and it also amalgamates other
778            characters into ranges. This has reduced the number of entries in the
779            table from around 16,000 to around 3,000, thus reducing its size
780            considerably. I realized I did not need to use a tree structure after
781            all - a binary chop search is just as efficient. Having reduced the
782            number of entries, I extended their size from 6 bytes to 8 bytes to
783            allow for more data.
785        (d) Added support for Unicode script names via properties such as \p{Han}.
787    19. In UTF-8 mode, a backslash followed by a non-Ascii character was not
788        matching that character.
790    20. When matching a repeated Unicode property with a minimum greater than zero,
791        (for example \pL{2,}), PCRE could look past the end of the subject if it
792        reached it while seeking the minimum number of characters. This could
793        happen only if some of the characters were more than one byte long, because
794        there is a check for at least the minimum number of bytes.
796    21. Refactored the implementation of \p and \P so as to be more general, to
797        allow for more different types of property in future. This has changed the
798        compiled form incompatibly. Anybody with saved compiled patterns that use
799        \p or \P will have to recompile them.
801    22. Added "Any" and "L&" to the supported property types.
803    23. Recognize \x{...} as a code point specifier, even when not in UTF-8 mode,
804        but give a compile time error if the value is greater than 0xff.
806    24. The man pages for pcrepartial, pcreprecompile, and pcre_compile2 were
807        accidentally not being installed or uninstalled.
809    25. The pcre.h file was built from pcre.h.in, but the only changes that were
810        made were to insert the current release number. This seemed silly, because
811        it made things harder for people building PCRE on systems that don't run
812        "configure". I have turned pcre.h into a distributed file, no longer built
813        by "configure", with the version identification directly included. There is
814        no longer a pcre.h.in file.
816        However, this change necessitated a change to the pcre-config script as
817        well. It is built from pcre-config.in, and one of the substitutions was the
818        release number. I have updated configure.ac so that ./configure now finds
819        the release number by grepping pcre.h.
821    26. Added the ability to run the tests under valgrind.
824    Version 6.4 05-Sep-05
825    ---------------------
827     1. Change 6.0/10/(l) to pcregrep introduced a bug that caused separator lines
828        "--" to be printed when multiple files were scanned, even when none of the
829        -A, -B, or -C options were used. This is not compatible with Gnu grep, so I
830        consider it to be a bug, and have restored the previous behaviour.
832     2. A couple of code tidies to get rid of compiler warnings.
834     3. The pcretest program used to cheat by referring to symbols in the library
835        whose names begin with _pcre_. These are internal symbols that are not
836        really supposed to be visible externally, and in some environments it is
837        possible to suppress them. The cheating is now confined to including
838        certain files from the library's source, which is a bit cleaner.
840     4. Renamed pcre.in as pcre.h.in to go with pcrecpp.h.in; it also makes the
841        file's purpose clearer.
843     5. Reorganized pcre_ucp_findchar().
846    Version 6.3 15-Aug-05
847    ---------------------
849     1. The file libpcre.pc.in did not have general read permission in the tarball.
851     2. There were some problems when building without C++ support:
853        (a) If C++ support was not built, "make install" and "make test" still
854            tried to test it.
856        (b) There were problems when the value of CXX was explicitly set. Some
857            changes have been made to try to fix these, and ...
859        (c) --disable-cpp can now be used to explicitly disable C++ support.
861        (d) The use of @CPP_OBJ@ directly caused a blank line preceded by a
862            backslash in a target when C++ was disabled. This confuses some
863            versions of "make", apparently. Using an intermediate variable solves
864            this. (Same for CPP_LOBJ.)
866     3. $(LINK_FOR_BUILD) now includes $(CFLAGS_FOR_BUILD) and $(LINK)
867        (non-Windows) now includes $(CFLAGS) because these flags are sometimes
868        necessary on certain architectures.
870     4. Added a setting of -export-symbols-regex to the link command to remove
871        those symbols that are exported in the C sense, but actually are local
872        within the library, and not documented. Their names all begin with
873        "_pcre_". This is not a perfect job, because (a) we have to except some
874        symbols that pcretest ("illegally") uses, and (b) the facility isn't always
875        available (and never for static libraries). I have made a note to try to
876        find a way round (a) in the future.
879    Version 6.2 01-Aug-05
880    ---------------------
882     1. There was no test for integer overflow of quantifier values. A construction
883        such as {1111111111111111} would give undefined results. What is worse, if
884        a minimum quantifier for a parenthesized subpattern overflowed and became
885        negative, the calculation of the memory size went wrong. This could have
886        led to memory overwriting.
888     2. Building PCRE using VPATH was broken. Hopefully it is now fixed.
890     3. Added "b" to the 2nd argument of fopen() in dftables.c, for non-Unix-like
891        operating environments where this matters.
893     4. Applied Giuseppe Maxia's patch to add additional features for controlling
894        PCRE options from within the C++ wrapper.
896     5. Named capturing subpatterns were not being correctly counted when a pattern
897        was compiled. This caused two problems: (a) If there were more than 100
898        such subpatterns, the calculation of the memory needed for the whole
899        compiled pattern went wrong, leading to an overflow error. (b) Numerical
900        back references of the form \12, where the number was greater than 9, were
901        not recognized as back references, even though there were sufficient
902        previous subpatterns.
904     6. Two minor patches to pcrecpp.cc in order to allow it to compile on older
905        versions of gcc, e.g. 2.95.4.
908    Version 6.1 21-Jun-05
909    ---------------------
911     1. There was one reference to the variable "posix" in pcretest.c that was not
912        surrounded by "#if !defined NOPOSIX".
914     2. Make it possible to compile pcretest without DFA support, UTF8 support, or
915        the cross-check on the old pcre_info() function, for the benefit of the
916        cut-down version of PCRE that is currently imported into Exim.
918     3. A (silly) pattern starting with (?i)(?-i) caused an internal space
919        allocation error. I've done the easy fix, which wastes 2 bytes for sensible
920        patterns that start (?i) but I don't think that matters. The use of (?i) is
921        just an example; this all applies to the other options as well.
923     4. Since libtool seems to echo the compile commands it is issuing, the output
924        from "make" can be reduced a bit by putting "@" in front of each libtool
925        compile command.
927     5. Patch from the folks at Google for configure.in to be a bit more thorough
928        in checking for a suitable C++ installation before trying to compile the
929        C++ stuff. This should fix a reported problem when a compiler was present,
930        but no suitable headers.
932     6. The man pages all had just "PCRE" as their title. I have changed them to
933        be the relevant file name. I have also arranged that these names are
934        retained in the file doc/pcre.txt, which is a concatenation in text format
935        of all the man pages except the little individual ones for each function.
937     7. The NON-UNIX-USE file had not been updated for the different set of source
938        files that come with release 6. I also added a few comments about the C++
939        wrapper.
942    Version 6.0 07-Jun-05
943    ---------------------
945     1. Some minor internal re-organization to help with my DFA experiments.
947     2. Some missing #ifdef SUPPORT_UCP conditionals in pcretest and printint that
948        didn't matter for the library itself when fully configured, but did matter
949        when compiling without UCP support, or within Exim, where the ucp files are
950        not imported.
952     3. Refactoring of the library code to split up the various functions into
953        different source modules. The addition of the new DFA matching code (see
954        below) to a single monolithic source would have made it really too
955        unwieldy, quite apart from causing all the code to be include in a
956        statically linked application, when only some functions are used. This is
957        relevant even without the DFA addition now that patterns can be compiled in
958        one application and matched in another.
960        The downside of splitting up is that there have to be some external
961        functions and data tables that are used internally in different modules of
962        the library but which are not part of the API. These have all had their
963        names changed to start with "_pcre_" so that they are unlikely to clash
964        with other external names.
966     4. Added an alternate matching function, pcre_dfa_exec(), which matches using
967        a different (DFA) algorithm. Although it is slower than the original
968        function, it does have some advantages for certain types of matching
969        problem.
971     5. Upgrades to pcretest in order to test the features of pcre_dfa_exec(),
972        including restarting after a partial match.
974     6. A patch for pcregrep that defines INVALID_FILE_ATTRIBUTES if it is not
975        defined when compiling for Windows was sent to me. I have put it into the
976        code, though I have no means of testing or verifying it.
978     7. Added the pcre_refcount() auxiliary function.
980     8. Added the PCRE_FIRSTLINE option. This constrains an unanchored pattern to
981        match before or at the first newline in the subject string. In pcretest,
982        the /f option on a pattern can be used to set this.
984     9. A repeated \w when used in UTF-8 mode with characters greater than 256
985        would behave wrongly. This has been present in PCRE since release 4.0.
987    10. A number of changes to the pcregrep command:
989        (a) Refactored how -x works; insert ^(...)$ instead of setting
990            PCRE_ANCHORED and checking the length, in preparation for adding
991            something similar for -w.
993        (b) Added the -w (match as a word) option.
995        (c) Refactored the way lines are read and buffered so as to have more
996            than one at a time available.
998        (d) Implemented a pcregrep test script.
1000        (e) Added the -M (multiline match) option. This allows patterns to match
1001            over several lines of the subject. The buffering ensures that at least
1002            8K, or the rest of the document (whichever is the shorter) is available
1003            for matching (and similarly the previous 8K for lookbehind assertions).
1005        (f) Changed the --help output so that it now says
1007              -w, --word-regex(p)
1009            instead of two lines, one with "regex" and the other with "regexp"
1010            because that confused at least one person since the short forms are the
1011            same. (This required a bit of code, as the output is generated
1012            automatically from a table. It wasn't just a text change.)
1014        (g) -- can be used to terminate pcregrep options if the next thing isn't an
1015            option but starts with a hyphen. Could be a pattern or a path name
1016            starting with a hyphen, for instance.
1018        (h) "-" can be given as a file name to represent stdin.
1020        (i) When file names are being printed, "(standard input)" is used for
1021            the standard input, for compatibility with GNU grep. Previously
1022            "<stdin>" was used.
1024        (j) The option --label=xxx can be used to supply a name to be used for
1025            stdin when file names are being printed. There is no short form.
1027        (k) Re-factored the options decoding logic because we are going to add
1028            two more options that take data. Such options can now be given in four
1029            different ways, e.g. "-fname", "-f name", "--file=name", "--file name".
1031        (l) Added the -A, -B, and -C options for requesting that lines of context
1032            around matches be printed.
1034        (m) Added the -L option to print the names of files that do not contain
1035            any matching lines, that is, the complement of -l.
1037        (n) The return code is 2 if any file cannot be opened, but pcregrep does
1038            continue to scan other files.
1040        (o) The -s option was incorrectly implemented. For compatibility with other
1041            greps, it now suppresses the error message for a non-existent or non-
1042            accessible file (but not the return code). There is a new option called
1043            -q that suppresses the output of matching lines, which was what -s was
1044            previously doing.
1046        (p) Added --include and --exclude options to specify files for inclusion
1047            and exclusion when recursing.
1049    11. The Makefile was not using the Autoconf-supported LDFLAGS macro properly.
1050        Hopefully, it now does.
1052    12. Missing cast in pcre_study().
1054    13. Added an "uninstall" target to the makefile.
1056    14. Replaced "extern" in the function prototypes in Makefile.in with
1057        "PCRE_DATA_SCOPE", which defaults to 'extern' or 'extern "C"' in the Unix
1058        world, but is set differently for Windows.
1060    15. Added a second compiling function called pcre_compile2(). The only
1061        difference is that it has an extra argument, which is a pointer to an
1062        integer error code. When there is a compile-time failure, this is set
1063        non-zero, in addition to the error test pointer being set to point to an
1064        error message. The new argument may be NULL if no error number is required
1065        (but then you may as well call pcre_compile(), which is now just a
1066        wrapper). This facility is provided because some applications need a
1067        numeric error indication, but it has also enabled me to tidy up the way
1068        compile-time errors are handled in the POSIX wrapper.
1070    16. Added VPATH=.libs to the makefile; this should help when building with one
1071        prefix path and installing with another. (Or so I'm told by someone who
1072        knows more about this stuff than I do.)
1074    17. Added a new option, REG_DOTALL, to the POSIX function regcomp(). This
1075        passes PCRE_DOTALL to the pcre_compile() function, making the "." character
1076        match everything, including newlines. This is not POSIX-compatible, but
1077        somebody wanted the feature. From pcretest it can be activated by using
1078        both the P and the s flags.
1080    18. AC_PROG_LIBTOOL appeared twice in Makefile.in. Removed one.
1082    19. libpcre.pc was being incorrectly installed as executable.
1084    20. A couple of places in pcretest check for end-of-line by looking for '\n';
1085        it now also looks for '\r' so that it will work unmodified on Windows.
1087    21. Added Google's contributed C++ wrapper to the distribution.
1089    22. Added some untidy missing memory free() calls in pcretest, to keep
1090        Electric Fence happy when testing.
1094    Version 5.0 13-Sep-04
1095    ---------------------
1097     1. Internal change: literal characters are no longer packed up into items
1098        containing multiple characters in a single byte-string. Each character
1099        is now matched using a separate opcode. However, there may be more than one
1100        byte in the character in UTF-8 mode.
1102     2. The pcre_callout_block structure has two new fields: pattern_position and
1103        next_item_length. These contain the offset in the pattern to the next match
1104        item, and its length, respectively.
1106     3. The PCRE_AUTO_CALLOUT option for pcre_compile() requests the automatic
1107        insertion of callouts before each pattern item. Added the /C option to
1108        pcretest to make use of this.
1110     4. On the advice of a Windows user, the lines
1112          #if defined(_WIN32) || defined(WIN32)
1113          _setmode( _fileno( stdout ), 0x8000 );
1114          #endif  /* defined(_WIN32) || defined(WIN32) */
1116        have been added to the source of pcretest. This apparently does useful
1117        magic in relation to line terminators.
1119     5. Changed "r" and "w" in the calls to fopen() in pcretest to "rb" and "wb"
1120        for the benefit of those environments where the "b" makes a difference.
1122     6. The icc compiler has the same options as gcc, but "configure" doesn't seem
1123        to know about it. I have put a hack into configure.in that adds in code
1124        to set GCC=yes if CC=icc. This seems to end up at a point in the
1125        generated configure script that is early enough to affect the setting of
1126        compiler options, which is what is needed, but I have no means of testing
1127        whether it really works. (The user who reported this had patched the
1128        generated configure script, which of course I cannot do.)
1130        LATER: After change 22 below (new libtool files), the configure script
1131        seems to know about icc (and also ecc). Therefore, I have commented out
1132        this hack in configure.in.
1134     7. Added support for pkg-config (2 patches were sent in).
1136     8. Negated POSIX character classes that used a combination of internal tables
1137        were completely broken. These were [[:^alpha:]], [[:^alnum:]], and
1138        [[:^ascii]]. Typically, they would match almost any characters. The other
1139        POSIX classes were not broken in this way.
1141     9. Matching the pattern "\b.*?" against "ab cd", starting at offset 1, failed
1142        to find the match, as PCRE was deluded into thinking that the match had to
1143        start at the start point or following a newline. The same bug applied to
1144        patterns with negative forward assertions or any backward assertions
1145        preceding ".*" at the start, unless the pattern required a fixed first
1146        character. This was a failing pattern: "(?!.bcd).*". The bug is now fixed.
1148    10. In UTF-8 mode, when moving forwards in the subject after a failed match
1149        starting at the last subject character, bytes beyond the end of the subject
1150        string were read.
1152    11. Renamed the variable "class" as "classbits" to make life easier for C++
1153        users. (Previously there was a macro definition, but it apparently wasn't
1154        enough.)
1156    12. Added the new field "tables" to the extra data so that tables can be passed
1157        in at exec time, or the internal tables can be re-selected. This allows
1158        a compiled regex to be saved and re-used at a later time by a different
1159        program that might have everything at different addresses.
1161    13. Modified the pcre-config script so that, when run on Solaris, it shows a
1162        -R library as well as a -L library.
1164    14. The debugging options of pcretest (-d on the command line or D on a
1165        pattern) showed incorrect output for anything following an extended class
1166        that contained multibyte characters and which was followed by a quantifier.
1168    15. Added optional support for general category Unicode character properties
1169        via the \p, \P, and \X escapes. Unicode property support implies UTF-8
1170        support. It adds about 90K to the size of the library. The meanings of the
1171        inbuilt class escapes such as \d and \s have NOT been changed.
1173    16. Updated pcredemo.c to include calls to free() to release the memory for the
1174        compiled pattern.
1176    17. The generated file chartables.c was being created in the source directory
1177        instead of in the building directory. This caused the build to fail if the
1178        source directory was different from the building directory, and was
1179        read-only.
1181    18. Added some sample Win commands from Mark Tetrode into the NON-UNIX-USE
1182        file. No doubt somebody will tell me if they don't make sense... Also added
1183        Dan Mooney's comments about building on OpenVMS.
1185    19. Added support for partial matching via the PCRE_PARTIAL option for
1186        pcre_exec() and the \P data escape in pcretest.
1188    20. Extended pcretest with 3 new pattern features:
1190        (i)   A pattern option of the form ">rest-of-line" causes pcretest to
1191              write the compiled pattern to the file whose name is "rest-of-line".
1192              This is a straight binary dump of the data, with the saved pointer to
1193              the character tables forced to be NULL. The study data, if any, is
1194              written too. After writing, pcretest reads a new pattern.
1196        (ii)  If, instead of a pattern, "<rest-of-line" is given, pcretest reads a
1197              compiled pattern from the given file. There must not be any
1198              occurrences of "<" in the file name (pretty unlikely); if there are,
1199              pcretest will instead treat the initial "<" as a pattern delimiter.
1200              After reading in the pattern, pcretest goes on to read data lines as
1201              usual.
1203        (iii) The F pattern option causes pcretest to flip the bytes in the 32-bit
1204              and 16-bit fields in a compiled pattern, to simulate a pattern that
1205              was compiled on a host of opposite endianness.
1207    21. The pcre-exec() function can now cope with patterns that were compiled on
1208        hosts of opposite endianness, with this restriction:
1210          As for any compiled expression that is saved and used later, the tables
1211          pointer field cannot be preserved; the extra_data field in the arguments
1212          to pcre_exec() should be used to pass in a tables address if a value
1213          other than the default internal tables were used at compile time.
1215    22. Calling pcre_exec() with a negative value of the "ovecsize" parameter is
1216        now diagnosed as an error. Previously, most of the time, a negative number
1217        would have been treated as zero, but if in addition "ovector" was passed as
1218        NULL, a crash could occur.
1220    23. Updated the files ltmain.sh, config.sub, config.guess, and aclocal.m4 with
1221        new versions from the libtool 1.5 distribution (the last one is a copy of
1222        a file called libtool.m4). This seems to have fixed the need to patch
1223        "configure" to support Darwin 1.3 (which I used to do). However, I still
1224        had to patch ltmain.sh to ensure that ${SED} is set (it isn't on my
1225        workstation).
1227    24. Changed the PCRE licence to be the more standard "BSD" licence.
1230    Version 4.5 01-Dec-03
1231    ---------------------
1233     1. There has been some re-arrangement of the code for the match() function so
1234        that it can be compiled in a version that does not call itself recursively.
1235        Instead, it keeps those local variables that need separate instances for
1236        each "recursion" in a frame on the heap, and gets/frees frames whenever it
1237        needs to "recurse". Keeping track of where control must go is done by means
1238        of setjmp/longjmp. The whole thing is implemented by a set of macros that
1239        hide most of the details from the main code, and operates only if
1240        NO_RECURSE is defined while compiling pcre.c. If PCRE is built using the
1241        "configure" mechanism, "--disable-stack-for-recursion" turns on this way of
1242        operating.
1244        To make it easier for callers to provide specially tailored get/free
1245        functions for this usage, two new functions, pcre_stack_malloc, and
1246        pcre_stack_free, are used. They are always called in strict stacking order,
1247        and the size of block requested is always the same.
1249        The PCRE_CONFIG_STACKRECURSE info parameter can be used to find out whether
1250        PCRE has been compiled to use the stack or the heap for recursion. The
1251        -C option of pcretest uses this to show which version is compiled.
1253        A new data escape \S, is added to pcretest; it causes the amounts of store
1254        obtained and freed by both kinds of malloc/free at match time to be added
1255        to the output.
1257     2. Changed the locale test to use "fr_FR" instead of "fr" because that's
1258        what's available on my current Linux desktop machine.
1260     3. When matching a UTF-8 string, the test for a valid string at the start has
1261        been extended. If start_offset is not zero, PCRE now checks that it points
1262        to a byte that is the start of a UTF-8 character. If not, it returns
1263        PCRE_ERROR_BADUTF8_OFFSET (-11). Note: the whole string is still checked;
1264        this is necessary because there may be backward assertions in the pattern.
1265        When matching the same subject several times, it may save resources to use
1266        PCRE_NO_UTF8_CHECK on all but the first call if the string is long.
1268     4. The code for checking the validity of UTF-8 strings has been tightened so
1269        that it rejects (a) strings containing 0xfe or 0xff bytes and (b) strings
1270        containing "overlong sequences".
1272     5. Fixed a bug (appearing twice) that I could not find any way of exploiting!
1273        I had written "if ((digitab[*p++] && chtab_digit) == 0)" where the "&&"
1274        should have been "&", but it just so happened that all the cases this let
1275        through by mistake were picked up later in the function.
1277     6. I had used a variable called "isblank" - this is a C99 function, causing
1278        some compilers to warn. To avoid this, I renamed it (as "blankclass").
1280     7. Cosmetic: (a) only output another newline at the end of pcretest if it is
1281        prompting; (b) run "./pcretest /dev/null" at the start of the test script
1282        so the version is shown; (c) stop "make test" echoing "./RunTest".
1284     8. Added patches from David Burgess to enable PCRE to run on EBCDIC systems.
1286     9. The prototype for memmove() for systems that don't have it was using
1287        size_t, but the inclusion of the header that defines size_t was later. I've
1288        moved the #includes for the C headers earlier to avoid this.
1290    10. Added some adjustments to the code to make it easier to compiler on certain
1291        special systems:
1293          (a) Some "const" qualifiers were missing.
1294          (b) Added the macro EXPORT before all exported functions; by default this
1295              is defined to be empty.
1296          (c) Changed the dftables auxiliary program (that builds chartables.c) so
1297              that it reads its output file name as an argument instead of writing
1298              to the standard output and assuming this can be redirected.
1300    11. In UTF-8 mode, if a recursive reference (e.g. (?1)) followed a character
1301        class containing characters with values greater than 255, PCRE compilation
1302        went into a loop.
1304    12. A recursive reference to a subpattern that was within another subpattern
1305        that had a minimum quantifier of zero caused PCRE to crash. For example,
1306        (x(y(?2))z)? provoked this bug with a subject that got as far as the
1307        recursion. If the recursively-called subpattern itself had a zero repeat,
1308        that was OK.
1310    13. In pcretest, the buffer for reading a data line was set at 30K, but the
1311        buffer into which it was copied (for escape processing) was still set at
1312        1024, so long lines caused crashes.
1314    14. A pattern such as /[ab]{1,3}+/ failed to compile, giving the error
1315        "internal error: code overflow...". This applied to any character class
1316        that was followed by a possessive quantifier.
1318    15. Modified the Makefile to add libpcre.la as a prerequisite for
1319        libpcreposix.la because I was told this is needed for a parallel build to
1320        work.
1322    16. If a pattern that contained .* following optional items at the start was
1323        studied, the wrong optimizing data was generated, leading to matching
1324        errors. For example, studying /[ab]*.*c/ concluded, erroneously, that any
1325        matching string must start with a or b or c. The correct conclusion for
1326        this pattern is that a match can start with any character.
1329    Version 4.4 13-Aug-03
1330    ---------------------
1332     1. In UTF-8 mode, a character class containing characters with values between
1333        127 and 255 was not handled correctly if the compiled pattern was studied.
1334        In fixing this, I have also improved the studying algorithm for such
1335        classes (slightly).
1337     2. Three internal functions had redundant arguments passed to them. Removal
1338        might give a very teeny performance improvement.
1340     3. Documentation bug: the value of the capture_top field in a callout is *one
1341        more than* the number of the hightest numbered captured substring.
1343     4. The Makefile linked pcretest and pcregrep with -lpcre, which could result
1344        in incorrectly linking with a previously installed version. They now link
1345        explicitly with libpcre.la.
1347     5. configure.in no longer needs to recognize Cygwin specially.
1349     6. A problem in pcre.in for Windows platforms is fixed.
1351     7. If a pattern was successfully studied, and the -d (or /D) flag was given to
1352        pcretest, it used to include the size of the study block as part of its
1353        output. Unfortunately, the structure contains a field that has a different
1354        size on different hardware architectures. This meant that the tests that
1355        showed this size failed. As the block is currently always of a fixed size,
1356        this information isn't actually particularly useful in pcretest output, so
1357        I have just removed it.
1359     8. Three pre-processor statements accidentally did not start in column 1.
1360        Sadly, there are *still* compilers around that complain, even though
1361        standard C has not required this for well over a decade. Sigh.
1363     9. In pcretest, the code for checking callouts passed small integers in the
1364        callout_data field, which is a void * field. However, some picky compilers
1365        complained about the casts involved for this on 64-bit systems. Now
1366        pcretest passes the address of the small integer instead, which should get
1367        rid of the warnings.
1369    10. By default, when in UTF-8 mode, PCRE now checks for valid UTF-8 strings at
1370        both compile and run time, and gives an error if an invalid UTF-8 sequence
1371        is found. There is a option for disabling this check in cases where the
1372        string is known to be correct and/or the maximum performance is wanted.
1374    11. In response to a bug report, I changed one line in Makefile.in from
1376            -Wl,--out-implib,.libs/lib@WIN_PREFIX@pcreposix.dll.a \
1377        to
1378            -Wl,--out-implib,.libs/@WIN_PREFIX@libpcreposix.dll.a \
1380        to look similar to other lines, but I have no way of telling whether this
1381        is the right thing to do, as I do not use Windows. No doubt I'll get told
1382        if it's wrong...
1385    Version 4.3 21-May-03
1386    ---------------------
1388    1. Two instances of @WIN_PREFIX@ omitted from the Windows targets in the
1389       Makefile.
1391    2. Some refactoring to improve the quality of the code:
1393       (i)   The utf8_table... variables are now declared "const".
1395       (ii)  The code for \cx, which used the "case flipping" table to upper case
1396             lower case letters, now just substracts 32. This is ASCII-specific,
1397             but the whole concept of \cx is ASCII-specific, so it seems
1398             reasonable.
1400       (iii) PCRE was using its character types table to recognize decimal and
1401             hexadecimal digits in the pattern. This is silly, because it handles
1402             only 0-9, a-f, and A-F, but the character types table is locale-
1403             specific, which means strange things might happen. A private
1404             table is now used for this - though it costs 256 bytes, a table is
1405             much faster than multiple explicit tests. Of course, the standard
1406             character types table is still used for matching digits in subject
1407             strings against \d.
1409       (iv)  Strictly, the identifier ESC_t is reserved by POSIX (all identifiers
1410             ending in _t are). So I've renamed it as ESC_tee.
1412    3. The first argument for regexec() in the POSIX wrapper should have been
1413       defined as "const".
1415    4. Changed pcretest to use malloc() for its buffers so that they can be
1416       Electric Fenced for debugging.
1418    5. There were several places in the code where, in UTF-8 mode, PCRE would try
1419       to read one or more bytes before the start of the subject string. Often this
1420       had no effect on PCRE's behaviour, but in some circumstances it could
1421       provoke a segmentation fault.
1423    6. A lookbehind at the start of a pattern in UTF-8 mode could also cause PCRE
1424       to try to read one or more bytes before the start of the subject string.
1426    7. A lookbehind in a pattern matched in non-UTF-8 mode on a PCRE compiled with
1427       UTF-8 support could misbehave in various ways if the subject string
1428       contained bytes with the 0x80 bit set and the 0x40 bit unset in a lookbehind
1429       area. (PCRE was not checking for the UTF-8 mode flag, and trying to move
1430       back over UTF-8 characters.)
1433    Version 4.2 14-Apr-03
1434    ---------------------
1436    1. Typo "#if SUPPORT_UTF8" instead of "#ifdef SUPPORT_UTF8" fixed.
1438    2. Changes to the building process, supplied by Ronald Landheer-Cieslak
1439         [ON_WINDOWS]: new variable, "#" on non-Windows platforms
1440         [NOT_ON_WINDOWS]: new variable, "#" on Windows platforms
1441         [WIN_PREFIX]: new variable, "cyg" for Cygwin
1442         * Makefile.in: use autoconf substitution for OBJEXT, EXEEXT, BUILD_OBJEXT
1443           and BUILD_EXEEXT
1444         Note: automatic setting of the BUILD variables is not yet working
1445         set CPPFLAGS and BUILD_CPPFLAGS (but don't use yet) - should be used at
1446           compile-time but not at link-time
1447         [LINK]: use for linking executables only
1448         make different versions for Windows and non-Windows
1449         [LINKLIB]: new variable, copy of UNIX-style LINK, used for linking
1450           libraries
1451         [LINK_FOR_BUILD]: new variable
1452         [OBJEXT]: use throughout
1453         [EXEEXT]: use throughout
1454         <winshared>: new target
1455         <wininstall>: new target
1456         <dftables.o>: use native compiler
1457         <dftables>: use native linker
1458         <install>: handle Windows platform correctly
1459         <clean>: ditto
1460         <check>: ditto
1461         copy DLL to top builddir before testing
1463       As part of these changes, -no-undefined was removed again. This was reported
1464       to give trouble on HP-UX 11.0, so getting rid of it seems like a good idea
1465       in any case.
1467    3. Some tidies to get rid of compiler warnings:
1469       . In the match_data structure, match_limit was an unsigned long int, whereas
1470         match_call_count was an int. I've made them both unsigned long ints.
1472       . In pcretest the fact that a const uschar * doesn't automatically cast to
1473         a void * provoked a warning.
1475       . Turning on some more compiler warnings threw up some "shadow" variables
1476         and a few more missing casts.
1478    4. If PCRE was complied with UTF-8 support, but called without the PCRE_UTF8
1479       option, a class that contained a single character with a value between 128
1480       and 255 (e.g. /[\xFF]/) caused PCRE to crash.
1482    5. If PCRE was compiled with UTF-8 support, but called without the PCRE_UTF8
1483       option, a class that contained several characters, but with at least one
1484       whose value was between 128 and 255 caused PCRE to crash.
1487    Version 4.1 12-Mar-03
1488    ---------------------
1490    1. Compiling with gcc -pedantic found a couple of places where casts were
1491    needed, and a string in dftables.c that was longer than standard compilers are
1492    required to support.
1494    2. Compiling with Sun's compiler found a few more places where the code could
1495    be tidied up in order to avoid warnings.
1497    3. The variables for cross-compiling were called HOST_CC and HOST_CFLAGS; the
1498    first of these names is deprecated in the latest Autoconf in favour of the name
1499    CC_FOR_BUILD, because "host" is typically used to mean the system on which the
1500    compiled code will be run. I can't find a reference for HOST_CFLAGS, but by
1501    analogy I have changed it to CFLAGS_FOR_BUILD.
1503    4. Added -no-undefined to the linking command in the Makefile, because this is
1504    apparently helpful for Windows. To make it work, also added "-L. -lpcre" to the
1505    linking step for the pcreposix library.
1507    5. PCRE was failing to diagnose the case of two named groups with the same
1508    name.
1510    6. A problem with one of PCRE's optimizations was discovered. PCRE remembers a
1511    literal character that is needed in the subject for a match, and scans along to
1512    ensure that it is present before embarking on the full matching process. This
1513    saves time in cases of nested unlimited repeats that are never going to match.
1514    Problem: the scan can take a lot of time if the subject is very long (e.g.
1515    megabytes), thus penalizing straightforward matches. It is now done only if the
1516    amount of subject to be scanned is less than 1000 bytes.
1518    7. A lesser problem with the same optimization is that it was recording the
1519    first character of an anchored pattern as "needed", thus provoking a search
1520    right along the subject, even when the first match of the pattern was going to
1521    fail. The "needed" character is now not set for anchored patterns, unless it
1522    follows something in the pattern that is of non-fixed length. Thus, it still
1523    fulfils its original purpose of finding quick non-matches in cases of nested
1524    unlimited repeats, but isn't used for simple anchored patterns such as /^abc/.
1527    Version 4.0 17-Feb-03
1528    ---------------------
1530    1. If a comment in an extended regex that started immediately after a meta-item
1531    extended to the end of string, PCRE compiled incorrect data. This could lead to
1532    all kinds of weird effects. Example: /#/ was bad; /()#/ was bad; /a#/ was not.
1534    2. Moved to autoconf 2.53 and libtool 1.4.2.
1536    3. Perl 5.8 no longer needs "use utf8" for doing UTF-8 things. Consequently,
1537    the special perltest8 script is no longer needed - all the tests can be run
1538    from a single perltest script.
1540    4. From 5.004, Perl has not included the VT character (0x0b) in the set defined
1541    by \s. It has now been removed in PCRE. This means it isn't recognized as
1542    whitespace in /x regexes too, which is the same as Perl. Note that the POSIX
1543    class [:space:] *does* include VT, thereby creating a mess.
1545    5. Added the class [:blank:] (a GNU extension from Perl 5.8) to match only
1546    space and tab.
1548    6. Perl 5.005 was a long time ago. It's time to amalgamate the tests that use
1549    its new features into the main test script, reducing the number of scripts.
1551    7. Perl 5.8 has changed the meaning of patterns like /a(?i)b/. Earlier versions
1552    were backward compatible, and made the (?i) apply to the whole pattern, as if
1553    /i were given. Now it behaves more logically, and applies the option setting
1554    only to what follows. PCRE has been changed to follow suit. However, if it
1555    finds options settings right at the start of the pattern, it extracts them into
1556    the global options, as before. Thus, they show up in the info data.
1558    8. Added support for the \Q...\E escape sequence. Characters in between are
1559    treated as literals. This is slightly different from Perl in that $ and @ are
1560    also handled as literals inside the quotes. In Perl, they will cause variable
1561    interpolation. Note the following examples:
1563        Pattern            PCRE matches      Perl matches
1565        \Qabc$xyz\E        abc$xyz           abc followed by the contents of $xyz
1566        \Qabc\$xyz\E       abc\$xyz          abc\$xyz
1567        \Qabc\E\$\Qxyz\E   abc$xyz           abc$xyz
1569    For compatibility with Perl, \Q...\E sequences are recognized inside character
1570    classes as well as outside them.
1572    9. Re-organized 3 code statements in pcretest to avoid "overflow in
1573    floating-point constant arithmetic" warnings from a Microsoft compiler. Added a
1574    (size_t) cast to one statement in pcretest and one in pcreposix to avoid
1575    signed/unsigned warnings.
1577    10. SunOS4 doesn't have strtoul(). This was used only for unpicking the -o
1578    option for pcretest, so I've replaced it by a simple function that does just
1579    that job.
1581    11. pcregrep was ending with code 0 instead of 2 for the commands "pcregrep" or
1582    "pcregrep -".
1584    12. Added "possessive quantifiers" ?+, *+, ++, and {,}+ which come from Sun's
1585    Java package. This provides some syntactic sugar for simple cases of what my
1586    documentation calls "once-only subpatterns". A pattern such as x*+ is the same
1587    as (?>x*). In other words, if what is inside (?>...) is just a single repeated
1588    item, you can use this simplified notation. Note that only makes sense with
1589    greedy quantifiers. Consequently, the use of the possessive quantifier forces
1590    greediness, whatever the setting of the PCRE_UNGREEDY option.
1592    13. A change of greediness default within a pattern was not taking effect at
1593    the current level for patterns like /(b+(?U)a+)/. It did apply to parenthesized
1594    subpatterns that followed. Patterns like /b+(?U)a+/ worked because the option
1595    was abstracted outside.
1597    14. PCRE now supports the \G assertion. It is true when the current matching
1598    position is at the start point of the match. This differs from \A when the
1599    starting offset is non-zero. Used with the /g option of pcretest (or similar
1600    code), it works in the same way as it does for Perl's /g option. If all
1601    alternatives of a regex begin with \G, the expression is anchored to the start
1602    match position, and the "anchored" flag is set in the compiled expression.
1604    15. Some bugs concerning the handling of certain option changes within patterns
1605    have been fixed. These applied to options other than (?ims). For example,
1606    "a(?x: b c )d" did not match "XabcdY" but did match "Xa b c dY". It should have
1607    been the other way round. Some of this was related to change 7 above.
1609    16. PCRE now gives errors for /[.x.]/ and /[=x=]/ as unsupported POSIX
1610    features, as Perl does. Previously, PCRE gave the warnings only for /[[.x.]]/
1611    and /[[=x=]]/. PCRE now also gives an error for /[:name:]/ because it supports
1612    POSIX classes only within a class (e.g. /[[:alpha:]]/).
1614    17. Added support for Perl's \C escape. This matches one byte, even in UTF8
1615    mode. Unlike ".", it always matches newline, whatever the setting of
1616    PCRE_DOTALL. However, PCRE does not permit \C to appear in lookbehind
1617    assertions. Perl allows it, but it doesn't (in general) work because it can't
1618    calculate the length of the lookbehind. At least, that's the case for Perl
1619    5.8.0 - I've been told they are going to document that it doesn't work in
1620    future.
1622    18. Added an error diagnosis for escapes that PCRE does not support: these are
1623    \L, \l, \N, \P, \p, \U, \u, and \X.
1625    19. Although correctly diagnosing a missing ']' in a character class, PCRE was
1626    reading past the end of the pattern in cases such as /[abcd/.
1628    20. PCRE was getting more memory than necessary for patterns with classes that
1629    contained both POSIX named classes and other characters, e.g. /[[:space:]abc/.
1631    21. Added some code, conditional on #ifdef VPCOMPAT, to make life easier for
1632    compiling PCRE for use with Virtual Pascal.
1634    22. Small fix to the Makefile to make it work properly if the build is done
1635    outside the source tree.
1637    23. Added a new extension: a condition to go with recursion. If a conditional
1638    subpattern starts with (?(R) the "true" branch is used if recursion has
1639    happened, whereas the "false" branch is used only at the top level.
1641    24. When there was a very long string of literal characters (over 255 bytes
1642    without UTF support, over 250 bytes with UTF support), the computation of how
1643    much memory was required could be incorrect, leading to segfaults or other
1644    strange effects.
1646    25. PCRE was incorrectly assuming anchoring (either to start of subject or to
1647    start of line for a non-DOTALL pattern) when a pattern started with (.*) and
1648    there was a subsequent back reference to those brackets. This meant that, for
1649    example, /(.*)\d+\1/ failed to match "abc123bc". Unfortunately, it isn't
1650    possible to check for precisely this case. All we can do is abandon the
1651    optimization if .* occurs inside capturing brackets when there are any back
1652    references whatsoever. (See below for a better fix that came later.)
1654    26. The handling of the optimization for finding the first character of a
1655    non-anchored pattern, and for finding a character that is required later in the
1656    match were failing in some cases. This didn't break the matching; it just
1657    failed to optimize when it could. The way this is done has been re-implemented.
1659    27. Fixed typo in error message for invalid (?R item (it said "(?p").
1661    28. Added a new feature that provides some of the functionality that Perl
1662    provides with (?{...}). The facility is termed a "callout". The way it is done
1663    in PCRE is for the caller to provide an optional function, by setting
1664    pcre_callout to its entry point. Like pcre_malloc and pcre_free, this is a
1665    global variable. By default it is unset, which disables all calling out. To get
1666    the function called, the regex must include (?C) at appropriate points. This
1667    is, in fact, equivalent to (?C0), and any number <= 255 may be given with (?C).
1668    This provides a means of identifying different callout points. When PCRE
1669    reaches such a point in the regex, if pcre_callout has been set, the external
1670    function is called. It is provided with data in a structure called
1671    pcre_callout_block, which is defined in pcre.h. If the function returns 0,
1672    matching continues; if it returns a non-zero value, the match at the current
1673    point fails. However, backtracking will occur if possible. [This was changed
1674    later and other features added - see item 49 below.]
1676    29. pcretest is upgraded to test the callout functionality. It provides a
1677    callout function that displays information. By default, it shows the start of
1678    the match and the current position in the text. There are some new data escapes
1679    to vary what happens:
1681        \C+         in addition, show current contents of captured substrings
1682        \C-         do not supply a callout function
1683        \C!n        return 1 when callout number n is reached
1684        \C!n!m      return 1 when callout number n is reached for the mth time
1686    30. If pcregrep was called with the -l option and just a single file name, it
1687    output "<stdin>" if a match was found, instead of the file name.
1689    31. Improve the efficiency of the POSIX API to PCRE. If the number of capturing
1690    slots is less than POSIX_MALLOC_THRESHOLD, use a block on the stack to pass to
1691    pcre_exec(). This saves a malloc/free per call. The default value of
1692    POSIX_MALLOC_THRESHOLD is 10; it can be changed by --with-posix-malloc-threshold
1693    when configuring.
1695    32. The default maximum size of a compiled pattern is 64K. There have been a
1696    few cases of people hitting this limit. The code now uses macros to handle the
1697    storing of links as offsets within the compiled pattern. It defaults to 2-byte
1698    links, but this can be changed to 3 or 4 bytes by --with-link-size when
1699    configuring. Tests 2 and 5 work only with 2-byte links because they output
1700    debugging information about compiled patterns.
1702    33. Internal code re-arrangements:
1704    (a) Moved the debugging function for printing out a compiled regex into
1705        its own source file (printint.c) and used #include to pull it into
1706        pcretest.c and, when DEBUG is defined, into pcre.c, instead of having two
1707        separate copies.
1709    (b) Defined the list of op-code names for debugging as a macro in
1710        internal.h so that it is next to the definition of the opcodes.
1712    (c) Defined a table of op-code lengths for simpler skipping along compiled
1713        code. This is again a macro in internal.h so that it is next to the
1714        definition of the opcodes.
1716    34. Added support for recursive calls to individual subpatterns, along the
1717    lines of Robin Houston's patch (but implemented somewhat differently).
1719    35. Further mods to the Makefile to help Win32. Also, added code to pcregrep to
1720    allow it to read and process whole directories in Win32. This code was
1721    contributed by Lionel Fourquaux; it has not been tested by me.
1723    36. Added support for named subpatterns. The Python syntax (?P<name>...) is
1724    used to name a group. Names consist of alphanumerics and underscores, and must
1725    be unique. Back references use the syntax (?P=name) and recursive calls use
1726    (?P>name) which is a PCRE extension to the Python extension. Groups still have
1727    numbers. The function pcre_fullinfo() can be used after compilation to extract
1728    a name/number map. There are three relevant calls:
1730      PCRE_INFO_NAMEENTRYSIZE        yields the size of each entry in the map
1731      PCRE_INFO_NAMECOUNT            yields the number of entries
1732      PCRE_INFO_NAMETABLE            yields a pointer to the map.
1734    The map is a vector of fixed-size entries. The size of each entry depends on
1735    the length of the longest name used. The first two bytes of each entry are the
1736    group number, most significant byte first. There follows the corresponding
1737    name, zero terminated. The names are in alphabetical order.
1739    37. Make the maximum literal string in the compiled code 250 for the non-UTF-8
1740    case instead of 255. Making it the same both with and without UTF-8 support
1741    means that the same test output works with both.
1743    38. There was a case of malloc(0) in the POSIX testing code in pcretest. Avoid
1744    calling malloc() with a zero argument.
1746    39. Change 25 above had to resort to a heavy-handed test for the .* anchoring
1747    optimization. I've improved things by keeping a bitmap of backreferences with
1748    numbers 1-31 so that if .* occurs inside capturing brackets that are not in
1749    fact referenced, the optimization can be applied. It is unlikely that a
1750    relevant occurrence of .* (i.e. one which might indicate anchoring or forcing
1751    the match to follow \n) will appear inside brackets with a number greater than
1752    31, but if it does, any back reference > 31 suppresses the optimization.
1754    40. Added a new compile-time option PCRE_NO_AUTO_CAPTURE. This has the effect
1755    of disabling numbered capturing parentheses. Any opening parenthesis that is
1756    not followed by ? behaves as if it were followed by ?: but named parentheses
1757    can still be used for capturing (and they will acquire numbers in the usual
1758    way).
1760    41. Redesigned the return codes from the match() function into yes/no/error so
1761    that errors can be passed back from deep inside the nested calls. A malloc
1762    failure while inside a recursive subpattern call now causes the
1763    PCRE_ERROR_NOMEMORY return instead of quietly going wrong.
1765    42. It is now possible to set a limit on the number of times the match()
1766    function is called in a call to pcre_exec(). This facility makes it possible to
1767    limit the amount of recursion and backtracking, though not in a directly
1768    obvious way, because the match() function is used in a number of different
1769    circumstances. The count starts from zero for each position in the subject
1770    string (for non-anchored patterns). The default limit is, for compatibility, a
1771    large number, namely 10 000 000. You can change this in two ways:
1773    (a) When configuring PCRE before making, you can use --with-match-limit=n
1774        to set a default value for the compiled library.
1776    (b) For each call to pcre_exec(), you can pass a pcre_extra block in which
1777        a different value is set. See 45 below.
1779    If the limit is exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT.
1781    43. Added a new function pcre_config(int, void *) to enable run-time extraction
1782    of things that can be changed at compile time. The first argument specifies
1783    what is wanted and the second points to where the information is to be placed.
1784    The current list of available information is:
1786      PCRE_CONFIG_UTF8
1788    The output is an integer that is set to one if UTF-8 support is available;
1789    otherwise it is set to zero.
1793    The output is an integer that it set to the value of the code that is used for
1794    newline. It is either LF (10) or CR (13).
1798    The output is an integer that contains the number of bytes used for internal
1799    linkage in compiled expressions. The value is 2, 3, or 4. See item 32 above.
1803    The output is an integer that contains the threshold above which the POSIX
1804    interface uses malloc() for output vectors. See item 31 above.
1808    The output is an unsigned integer that contains the default limit of the number
1809    of match() calls in a pcre_exec() execution. See 42 above.
1811    44. pcretest has been upgraded by the addition of the -C option. This causes it
1812    to extract all the available output from the new pcre_config() function, and to
1813    output it. The program then exits immediately.
1815    45. A need has arisen to pass over additional data with calls to pcre_exec() in
1816    order to support additional features. One way would have been to define
1817    pcre_exec2() (for example) with extra arguments, but this would not have been
1818    extensible, and would also have required all calls to the original function to
1819    be mapped to the new one. Instead, I have chosen to extend the mechanism that
1820    is used for passing in "extra" data from pcre_study().
1822    The pcre_extra structure is now exposed and defined in pcre.h. It currently
1823    contains the following fields:
1825      flags         a bitmap indicating which of the following fields are set
1826      study_data    opaque data from pcre_study()
1827      match_limit   a way of specifying a limit on match() calls for a specific
1828                      call to pcre_exec()
1829      callout_data  data for callouts (see 49 below)
1831    The flag bits are also defined in pcre.h, and are
1837    The pcre_study() function now returns one of these new pcre_extra blocks, with
1838    the actual study data pointed to by the study_data field, and the
1839    PCRE_EXTRA_STUDY_DATA flag set. This can be passed directly to pcre_exec() as
1840    before. That is, this change is entirely upwards-compatible and requires no
1841    change to existing code.
1843    If you want to pass in additional data to pcre_exec(), you can either place it
1844    in a pcre_extra block provided by pcre_study(), or create your own pcre_extra
1845    block.
1847    46. pcretest has been extended to test the PCRE_EXTRA_MATCH_LIMIT feature. If a
1848    data string contains the escape sequence \M, pcretest calls pcre_exec() several
1849    times with different match limits, until it finds the minimum value needed for
1850    pcre_exec() to complete. The value is then output. This can be instructive; for
1851    most simple matches the number is quite small, but for pathological cases it
1852    gets very large very quickly.
1854    47. There's a new option for pcre_fullinfo() called PCRE_INFO_STUDYSIZE. It
1855    returns the size of the data block pointed to by the study_data field in a
1856    pcre_extra block, that is, the value that was passed as the argument to
1857    pcre_malloc() when PCRE was getting memory in which to place the information
1858    created by pcre_study(). The fourth argument should point to a size_t variable.
1859    pcretest has been extended so that this information is shown after a successful
1860    pcre_study() call when information about the compiled regex is being displayed.
1862    48. Cosmetic change to Makefile: there's no need to have / after $(DESTDIR)
1863    because what follows is always an absolute path. (Later: it turns out that this
1864    is more than cosmetic for MinGW, because it doesn't like empty path
1865    components.)
1867    49. Some changes have been made to the callout feature (see 28 above):
1869    (i)  A callout function now has three choices for what it returns:
1871           0  =>  success, carry on matching
1872         > 0  =>  failure at this point, but backtrack if possible
1873         < 0  =>  serious error, return this value from pcre_exec()
1875         Negative values should normally be chosen from the set of PCRE_ERROR_xxx
1876         values. In particular, returning PCRE_ERROR_NOMATCH forces a standard
1877         "match failed" error. The error number PCRE_ERROR_CALLOUT is reserved for
1878         use by callout functions. It will never be used by PCRE itself.
1880    (ii) The pcre_extra structure (see 45 above) has a void * field called
1881         callout_data, with corresponding flag bit PCRE_EXTRA_CALLOUT_DATA. The
1882         pcre_callout_block structure has a field of the same name. The contents of
1883         the field passed in the pcre_extra structure are passed to the callout
1884         function in the corresponding field in the callout block. This makes it
1885         easier to use the same callout-containing regex from multiple threads. For
1886         testing, the pcretest program has a new data escape
1888           \C*n        pass the number n (may be negative) as callout_data
1890         If the callout function in pcretest receives a non-zero value as
1891         callout_data, it returns that value.
1893    50. Makefile wasn't handling CFLAGS properly when compiling dftables. Also,
1894    there were some redundant $(CFLAGS) in commands that are now specified as
1895    $(LINK), which already includes $(CFLAGS).
1897    51. Extensions to UTF-8 support are listed below. These all apply when (a) PCRE
1898    has been compiled with UTF-8 support *and* pcre_compile() has been compiled
1899    with the PCRE_UTF8 flag. Patterns that are compiled without that flag assume
1900    one-byte characters throughout. Note that case-insensitive matching applies
1901    only to characters whose values are less than 256. PCRE doesn't support the
1902    notion of cases for higher-valued characters.
1904    (i)   A character class whose characters are all within 0-255 is handled as
1905          a bit map, and the map is inverted for negative classes. Previously, a
1906          character > 255 always failed to match such a class; however it should
1907          match if the class was a negative one (e.g. [^ab]). This has been fixed.
1909    (ii)  A negated character class with a single character < 255 is coded as
1910          "not this character" (OP_NOT). This wasn't working properly when the test
1911          character was multibyte, either singly or repeated.
1913    (iii) Repeats of multibyte characters are now handled correctly in UTF-8
1914          mode, for example: \x{100}{2,3}.
1916    (iv)  The character escapes \b, \B, \d, \D, \s, \S, \w, and \W (either
1917          singly or repeated) now correctly test multibyte characters. However,
1918          PCRE doesn't recognize any characters with values greater than 255 as
1919          digits, spaces, or word characters. Such characters always match \D, \S,
1920          and \W, and never match \d, \s, or \w.
1922    (v)   Classes may now contain characters and character ranges with values
1923          greater than 255. For example: [ab\x{100}-\x{400}].
1925    (vi)  pcregrep now has a --utf-8 option (synonym -u) which makes it call
1926          PCRE in UTF-8 mode.
1928    52. The info request value PCRE_INFO_FIRSTCHAR has been renamed
1929    PCRE_INFO_FIRSTBYTE because it is a byte value. However, the old name is
1930    retained for backwards compatibility. (Note that LASTLITERAL is also a byte
1931    value.)
1933    53. The single man page has become too large. I have therefore split it up into
1934    a number of separate man pages. These also give rise to individual HTML pages;
1935    these are now put in a separate directory, and there is an index.html page that
1936    lists them all. Some hyperlinking between the pages has been installed.
1938    54. Added convenience functions for handling named capturing parentheses.
1940    55. Unknown escapes inside character classes (e.g. [\M]) and escapes that
1941    aren't interpreted therein (e.g. [\C]) are literals in Perl. This is now also
1942    true in PCRE, except when the PCRE_EXTENDED option is set, in which case they
1943    are faulted.
1945    56. Introduced HOST_CC and HOST_CFLAGS which can be set in the environment when
1946    calling configure. These values are used when compiling the dftables.c program
1947    which is run to generate the source of the default character tables. They
1948    default to the values of CC and CFLAGS. If you are cross-compiling PCRE,
1949    you will need to set these values.
1951    57. Updated the building process for Windows DLL, as provided by Fred Cox.
1954    Version 3.9 02-Jan-02
1955    ---------------------
1957    1. A bit of extraneous text had somehow crept into the pcregrep documentation.
1959    2. If --disable-static was given, the building process failed when trying to
1960    build pcretest and pcregrep. (For some reason it was using libtool to compile
1961    them, which is not right, as they aren't part of the library.)
1964    Version 3.8 18-Dec-01
1965    ---------------------
1967    1. The experimental UTF-8 code was completely screwed up. It was packing the
1968    bytes in the wrong order. How dumb can you get?
1971    Version 3.7 29-Oct-01
1972    ---------------------
1974    1. In updating pcretest to check change 1 of version 3.6, I screwed up.
1975    This caused pcretest, when used on the test data, to segfault. Unfortunately,
1976    this didn't happen under Solaris 8, where I normally test things.
1978    2. The Makefile had to be changed to make it work on BSD systems, where 'make'
1979    doesn't seem to recognize that ./xxx and xxx are the same file. (This entry
1980    isn't in ChangeLog distributed with 3.7 because I forgot when I hastily made
1981    this fix an hour or so after the initial 3.7 release.)
1984  Version 3.6 23-Oct-01  Version 3.6 23-Oct-01
1985  ---------------------  ---------------------

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