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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
4    Version 7.4 21-Sep-07
5    ---------------------
7    1.  Change 7.3/28 was implemented for classes by looking at the bitmap. This
8        means that a class such as [\s] counted as "explicit reference to CR or
9        LF". That isn't really right - the whole point of the change was to try to
10        help when there was an actual mention of one of the two characters. So now
11        the change happens only if \r or \n (or a literal CR or LF) character is
12        encountered.
14    2.  The 32-bit options word was also used for 6 internal flags, but the numbers
15        of both had grown to the point where there were only 3 bits left.
16        Fortunately, there was spare space in the data structure, and so I have
17        moved the internal flags into a new 16-bit field to free up more option
18        bits.
20    3.  The appearance of (?J) at the start of a pattern set the DUPNAMES option,
21        but did not set the internal JCHANGED flag - either of these is enough to
22        control the way the "get" function works - but the PCRE_INFO_JCHANGED
23        facility is supposed to tell if (?J) was ever used, so now (?J) at the
24        start sets both bits.
26    4.  Added options (at build time, compile time, exec time) to change \R from
27        matching any Unicode line ending sequence to just matching CR, LF, or CRLF.
29    5.  doc/pcresyntax.html was missing from the distribution.
31    6.  Put back the definition of PCRE_ERROR_NULLWSLIMIT, for backward
32        compatibility, even though it is no longer used.
34    7.  Added macro for snprintf to pcrecpp_unittest.cc and also for strtoll and
35        strtoull to pcrecpp.cc to select the available functions in WIN32 when the
36        windows.h file is present (where different names are used). [This was
37        reversed later after testing - see 16 below.]
39    8.  Changed all #include <config.h> to #include "config.h". There were also
40        some further <pcre.h> cases that I changed to "pcre.h".
42    9.  When pcregrep was used with the --colour option, it missed the line ending
43        sequence off the lines that it output.
45    10. It was pointed out to me that arrays of string pointers cause lots of
46        relocations when a shared library is dynamically loaded. A technique of
47        using a single long string with a table of offsets can drastically reduce
48        these. I have refactored PCRE in four places to do this. The result is
49        dramatic:
51          Originally:                          290
52          After changing UCP table:            187
53          After changing error message table:   43
54          After changing table of "verbs"       36
55          After changing table of Posix names   22
57        Thanks to the folks working on Gregex for glib for this insight.
59    11. --disable-stack-for-recursion caused compiling to fail unless -enable-
60        unicode-properties was also set.
62    12. Updated the tests so that they work when \R is defaulted to ANYCRLF.
64    13. Added checks for ANY and ANYCRLF to pcrecpp.cc where it previously
65        checked only for CRLF.
67    14. Added casts to pcretest.c to avoid compiler warnings.
69    15. Added Craig's patch to various pcrecpp modules to avoid compiler warnings.
71    16. Added Craig's patch to remove the WINDOWS_H tests, that were not working,
72        and instead check for _strtoi64 explicitly, and avoid the use of snprintf()
73        entirely. This removes changes made in 7 above.
75    17. The CMake files have been updated, and there is now more information about
76        building with CMake in the NON-UNIX-USE document.
79    Version 7.3 28-Aug-07
80    ---------------------
82     1. In the rejigging of the build system that eventually resulted in 7.1, the
83        line "#include <pcre.h>" was included in pcre_internal.h. The use of angle
84        brackets there is not right, since it causes compilers to look for an
85        installed pcre.h, not the version that is in the source that is being
86        compiled (which of course may be different). I have changed it back to:
88          #include "pcre.h"
90        I have a vague recollection that the change was concerned with compiling in
91        different directories, but in the new build system, that is taken care of
92        by the VPATH setting the Makefile.
94     2. The pattern .*$ when run in not-DOTALL UTF-8 mode with newline=any failed
95        when the subject happened to end in the byte 0x85 (e.g. if the last
96        character was \x{1ec5}). *Character* 0x85 is one of the "any" newline
97        characters but of course it shouldn't be taken as a newline when it is part
98        of another character. The bug was that, for an unlimited repeat of . in
99        not-DOTALL UTF-8 mode, PCRE was advancing by bytes rather than by
100        characters when looking for a newline.
102     3. A small performance improvement in the DOTALL UTF-8 mode .* case.
104     4. Debugging: adjusted the names of opcodes for different kinds of parentheses
105        in debug output.
107     5. Arrange to use "%I64d" instead of "%lld" and "%I64u" instead of "%llu" for
108        long printing in the pcrecpp unittest when running under MinGW.
110     6. ESC_K was left out of the EBCDIC table.
112     7. Change 7.0/38 introduced a new limit on the number of nested non-capturing
113        parentheses; I made it 1000, which seemed large enough. Unfortunately, the
114        limit also applies to "virtual nesting" when a pattern is recursive, and in
115        this case 1000 isn't so big. I have been able to remove this limit at the
116        expense of backing off one optimization in certain circumstances. Normally,
117        when pcre_exec() would call its internal match() function recursively and
118        immediately return the result unconditionally, it uses a "tail recursion"
119        feature to save stack. However, when a subpattern that can match an empty
120        string has an unlimited repetition quantifier, it no longer makes this
121        optimization. That gives it a stack frame in which to save the data for
122        checking that an empty string has been matched. Previously this was taken
123        from the 1000-entry workspace that had been reserved. So now there is no
124        explicit limit, but more stack is used.
126     8. Applied Daniel's patches to solve problems with the import/export magic
127        syntax that is required for Windows, and which was going wrong for the
128        pcreposix and pcrecpp parts of the library. These were overlooked when this
129        problem was solved for the main library.
131     9. There were some crude static tests to avoid integer overflow when computing
132        the size of patterns that contain repeated groups with explicit upper
133        limits. As the maximum quantifier is 65535, the maximum group length was
134        set at 30,000 so that the product of these two numbers did not overflow a
135        32-bit integer. However, it turns out that people want to use groups that
136        are longer than 30,000 bytes (though not repeat them that many times).
137        Change 7.0/17 (the refactoring of the way the pattern size is computed) has
138        made it possible to implement the integer overflow checks in a much more
139        dynamic way, which I have now done. The artificial limitation on group
140        length has been removed - we now have only the limit on the total length of
141        the compiled pattern, which depends on the LINK_SIZE setting.
143    10. Fixed a bug in the documentation for get/copy named substring when
144        duplicate names are permitted. If none of the named substrings are set, the
145        functions return PCRE_ERROR_NOSUBSTRING (7); the doc said they returned an
146        empty string.
148    11. Because Perl interprets \Q...\E at a high level, and ignores orphan \E
149        instances, patterns such as [\Q\E] or [\E] or even [^\E] cause an error,
150        because the ] is interpreted as the first data character and the
151        terminating ] is not found. PCRE has been made compatible with Perl in this
152        regard. Previously, it interpreted [\Q\E] as an empty class, and [\E] could
153        cause memory overwriting.
155    10. Like Perl, PCRE automatically breaks an unlimited repeat after an empty
156        string has been matched (to stop an infinite loop). It was not recognizing
157        a conditional subpattern that could match an empty string if that
158        subpattern was within another subpattern. For example, it looped when
159        trying to match  (((?(1)X|))*)  but it was OK with  ((?(1)X|)*)  where the
160        condition was not nested. This bug has been fixed.
162    12. A pattern like \X?\d or \P{L}?\d in non-UTF-8 mode could cause a backtrack
163        past the start of the subject in the presence of bytes with the top bit
164        set, for example "\x8aBCD".
166    13. Added Perl 5.10 experimental backtracking controls (*FAIL), (*F), (*PRUNE),
167        (*SKIP), (*THEN), (*COMMIT), and (*ACCEPT).
169    14. Optimized (?!) to (*FAIL).
171    15. Updated the test for a valid UTF-8 string to conform to the later RFC 3629.
172        This restricts code points to be within the range 0 to 0x10FFFF, excluding
173        the "low surrogate" sequence 0xD800 to 0xDFFF. Previously, PCRE allowed the
174        full range 0 to 0x7FFFFFFF, as defined by RFC 2279. Internally, it still
175        does: it's just the validity check that is more restrictive.
177    16. Inserted checks for integer overflows during escape sequence (backslash)
178        processing, and also fixed erroneous offset values for syntax errors during
179        backslash processing.
181    17. Fixed another case of looking too far back in non-UTF-8 mode (cf 12 above)
182        for patterns like [\PPP\x8a]{1,}\x80 with the subject "A\x80".
184    18. An unterminated class in a pattern like (?1)\c[ with a "forward reference"
185        caused an overrun.
187    19. A pattern like (?:[\PPa*]*){8,} which had an "extended class" (one with
188        something other than just ASCII characters) inside a group that had an
189        unlimited repeat caused a loop at compile time (while checking to see
190        whether the group could match an empty string).
192    20. Debugging a pattern containing \p or \P could cause a crash. For example,
193        [\P{Any}] did so. (Error in the code for printing property names.)
195    21. An orphan \E inside a character class could cause a crash.
197    22. A repeated capturing bracket such as (A)? could cause a wild memory
198        reference during compilation.
200    23. There are several functions in pcre_compile() that scan along a compiled
201        expression for various reasons (e.g. to see if it's fixed length for look
202        behind). There were bugs in these functions when a repeated \p or \P was
203        present in the pattern. These operators have additional parameters compared
204        with \d, etc, and these were not being taken into account when moving along
205        the compiled data. Specifically:
207        (a) A item such as \p{Yi}{3} in a lookbehind was not treated as fixed
208            length.
210        (b) An item such as \pL+ within a repeated group could cause crashes or
211            loops.
213        (c) A pattern such as \p{Yi}+(\P{Yi}+)(?1) could give an incorrect
214            "reference to non-existent subpattern" error.
216        (d) A pattern like (\P{Yi}{2}\277)? could loop at compile time.
218    24. A repeated \S or \W in UTF-8 mode could give wrong answers when multibyte
219        characters were involved (for example /\S{2}/8g with "A\x{a3}BC").
221    25. Using pcregrep in multiline, inverted mode (-Mv) caused it to loop.
223    26. Patterns such as [\P{Yi}A] which include \p or \P and just one other
224        character were causing crashes (broken optimization).
226    27. Patterns such as (\P{Yi}*\277)* (group with possible zero repeat containing
227        \p or \P) caused a compile-time loop.
229    28. More problems have arisen in unanchored patterns when CRLF is a valid line
230        break. For example, the unstudied pattern [\r\n]A does not match the string
231        "\r\nA" because change 7.0/46 below moves the current point on by two
232        characters after failing to match at the start. However, the pattern \nA
233        *does* match, because it doesn't start till \n, and if [\r\n]A is studied,
234        the same is true. There doesn't seem any very clean way out of this, but
235        what I have chosen to do makes the common cases work: PCRE now takes note
236        of whether there can be an explicit match for \r or \n anywhere in the
237        pattern, and if so, 7.0/46 no longer applies. As part of this change,
238        there's a new PCRE_INFO_HASCRORLF option for finding out whether a compiled
239        pattern has explicit CR or LF references.
241    29. Added (*CR) etc for changing newline setting at start of pattern.
244    Version 7.2 19-Jun-07
245    ---------------------
247     1. If the fr_FR locale cannot be found for test 3, try the "french" locale,
248        which is apparently normally available under Windows.
250     2. Re-jig the pcregrep tests with different newline settings in an attempt
251        to make them independent of the local environment's newline setting.
253     3. Add code to configure.ac to remove -g from the CFLAGS default settings.
255     4. Some of the "internals" tests were previously cut out when the link size
256        was not 2, because the output contained actual offsets. The recent new
257        "Z" feature of pcretest means that these can be cut out, making the tests
258        usable with all link sizes.
260     5. Implemented Stan Switzer's goto replacement for longjmp() when not using
261        stack recursion. This gives a massive performance boost under BSD, but just
262        a small improvement under Linux. However, it saves one field in the frame
263        in all cases.
265     6. Added more features from the forthcoming Perl 5.10:
267        (a) (?-n) (where n is a string of digits) is a relative subroutine or
268            recursion call. It refers to the nth most recently opened parentheses.
270        (b) (?+n) is also a relative subroutine call; it refers to the nth next
271            to be opened parentheses.
273        (c) Conditions that refer to capturing parentheses can be specified
274            relatively, for example, (?(-2)... or (?(+3)...
276        (d) \K resets the start of the current match so that everything before
277            is not part of it.
279        (e) \k{name} is synonymous with \k<name> and \k'name' (.NET compatible).
281        (f) \g{name} is another synonym - part of Perl 5.10's unification of
282            reference syntax.
284        (g) (?| introduces a group in which the numbering of parentheses in each
285            alternative starts with the same number.
287        (h) \h, \H, \v, and \V match horizontal and vertical whitespace.
289     7. Added two new calls to pcre_fullinfo(): PCRE_INFO_OKPARTIAL and
292     8. A pattern such as  (.*(.)?)*  caused pcre_exec() to fail by either not
293        terminating or by crashing. Diagnosed by Viktor Griph; it was in the code
294        for detecting groups that can match an empty string.
296     9. A pattern with a very large number of alternatives (more than several
297        hundred) was running out of internal workspace during the pre-compile
298        phase, where pcre_compile() figures out how much memory will be needed. A
299        bit of new cunning has reduced the workspace needed for groups with
300        alternatives. The 1000-alternative test pattern now uses 12 bytes of
301        workspace instead of running out of the 4096 that are available.
303    10. Inserted some missing (unsigned int) casts to get rid of compiler warnings.
305    11. Applied patch from Google to remove an optimization that didn't quite work.
306        The report of the bug said:
308          pcrecpp::RE("a*").FullMatch("aaa") matches, while
309          pcrecpp::RE("a*?").FullMatch("aaa") does not, and
310          pcrecpp::RE("a*?\\z").FullMatch("aaa") does again.
312    12. If \p or \P was used in non-UTF-8 mode on a character greater than 127
313        it matched the wrong number of bytes.
316    Version 7.1 24-Apr-07
317    ---------------------
319     1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
320        that is more "standard", making use of automake and other Autotools. There
321        is some re-arrangement of the files and adjustment of comments consequent
322        on this.
324     2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
325        for recursive directory scanning broke on some systems because the files
326        are not scanned in any specific order and on different systems the order
327        was different. A call to "sort" has been inserted into RunGrepTest for the
328        approprate test as a short-term fix. In the longer term there may be an
329        alternative.
331     3. I had an email from Eric Raymond about problems translating some of PCRE's
332        man pages to HTML (despite the fact that I distribute HTML pages, some
333        people do their own conversions for various reasons). The problems
334        concerned the use of low-level troff macros .br and .in. I have therefore
335        removed all such uses from the man pages (some were redundant, some could
336        be replaced by .nf/.fi pairs). The 132html script that I use to generate
337        HTML has been updated to handle .nf/.fi and to complain if it encounters
338        .br or .in.
340     4. Updated comments in configure.ac that get placed in config.h.in and also
341        arranged for config.h to be included in the distribution, with the name
342        config.h.generic, for the benefit of those who have to compile without
343        Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
345     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
346        Weber: (1) pcre_internal.h was missing some function renames; (2) updated
347        makevp.bat for the current PCRE, using the additional files
348        makevp_c.txt, makevp_l.txt, and pcregexp.pas.
350     6. A Windows user reported a minor discrepancy with test 2, which turned out
351        to be caused by a trailing space on an input line that had got lost in his
352        copy. The trailing space was an accident, so I've just removed it.
354     7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
355        that is needed.
357     8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
358        as "const" (a) because they are and (b) because it helps the PHP
359        maintainers who have recently made a script to detect big data structures
360        in the php code that should be moved to the .rodata section. I remembered
361        to update Builducptable as well, so it won't revert if ucptable.h is ever
362        re-created.
364     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
365        pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
366        order to be able to cut out the UTF-8 tables in the latter when UTF-8
367        support is not required. This saves 1.5-2K of code, which is important in
368        some applications.
370        Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
371        so as not to refer to the tables, even though these functions will never be
372        called when UTF-8 support is disabled. Otherwise there are problems with a
373        shared library.
375    10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
377        (a) It was defining its arguments as char * instead of void *.
379        (b) It was assuming that all moves were upwards in memory; this was true
380            a long time ago when I wrote it, but is no longer the case.
382        The emulated memove() is provided for those environments that have neither
383        memmove() nor bcopy(). I didn't think anyone used it these days, but that
384        is clearly not the case, as these two bugs were recently reported.
386    11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
387        and Detrail to create the HTML documentation, the .txt form of the man
388        pages, and it removes trailing spaces from listed files. It also creates
389        pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
390        case, it wraps all the #defines with #ifndefs. This script should be run
391        before "make dist".
393    12. Fixed two fairly obscure bugs concerned with quantified caseless matching
394        with Unicode property support.
396        (a) For a maximizing quantifier, if the two different cases of the
397            character were of different lengths in their UTF-8 codings (there are
398            some cases like this - I found 11), and the matching function had to
399            back up over a mixture of the two cases, it incorrectly assumed they
400            were both the same length.
402        (b) When PCRE was configured to use the heap rather than the stack for
403            recursion during matching, it was not correctly preserving the data for
404            the other case of a UTF-8 character when checking ahead for a match
405            while processing a minimizing repeat. If the check also involved
406            matching a wide character, but failed, corruption could cause an
407            erroneous result when trying to check for a repeat of the original
408            character.
410    13. Some tidying changes to the testing mechanism:
412        (a) The RunTest script now detects the internal link size and whether there
413            is UTF-8 and UCP support by running ./pcretest -C instead of relying on
414            values substituted by "configure". (The RunGrepTest script already did
415            this for UTF-8.) The configure.ac script no longer substitutes the
416            relevant variables.
418        (b) The debugging options /B and /D in pcretest show the compiled bytecode
419            with length and offset values. This means that the output is different
420            for different internal link sizes. Test 2 is skipped for link sizes
421            other than 2 because of this, bypassing the problem. Unfortunately,
422            there was also a test in test 3 (the locale tests) that used /B and
423            failed for link sizes other than 2. Rather than cut the whole test out,
424            I have added a new /Z option to pcretest that replaces the length and
425            offset values with spaces. This is now used to make test 3 independent
426            of link size. (Test 2 will be tidied up later.)
428    14. If erroroffset was passed as NULL to pcre_compile, it provoked a
429        segmentation fault instead of returning the appropriate error message.
431    15. In multiline mode when the newline sequence was set to "any", the pattern
432        ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
433        This doesn't seem right; it now treats the CRLF combination as the line
434        ending, and so does not match in that case. It's only a pattern such as ^$
435        that would hit this one: something like ^ABC$ would have failed after \r
436        and then tried again after \r\n.
438    16. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
439        in an attempt to make files that differ only in their line terminators
440        compare equal. This works on Linux.
442    17. Under certain error circumstances pcregrep might try to free random memory
443        as it exited. This is now fixed, thanks to valgrind.
445    19. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
446        "abc\r\n\r\n", it found an unwanted second match after the second \r. This
447        was because its rules for how to advance for /g after matching an empty
448        string at the end of a line did not allow for this case. They now check for
449        it specially.
451    20. pcretest is supposed to handle patterns and data of any length, by
452        extending its buffers when necessary. It was getting this wrong when the
453        buffer for a data line had to be extended.
455    21. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or
456        CRLF as a newline sequence.
458    22. Code for handling Unicode properties in pcre_dfa_exec() wasn't being cut
459        out by #ifdef SUPPORT_UCP. This did no harm, as it could never be used, but
460        I have nevertheless tidied it up.
462    23. Added some casts to kill warnings from HP-UX ia64 compiler.
464    24. Added a man page for pcre-config.
467    Version 7.0 19-Dec-06
468    ---------------------
470     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
471        moving to gcc 4.1.1.
473     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
474        sys/time.h, which is documented as needed for this function. It doesn't
475        seem to matter on Linux, but it showed up on some releases of OS X.
477     3. It seems that there are systems where bytes whose values are greater than
478        127 match isprint() in the "C" locale. The "C" locale should be the
479        default when a C program starts up. In most systems, only ASCII printing
480        characters match isprint(). This difference caused the output from pcretest
481        to vary, making some of the tests fail. I have changed pcretest so that:
483        (a) When it is outputting text in the compiled version of a pattern, bytes
484            other than 32-126 are always shown as hex escapes.
486        (b) When it is outputting text that is a matched part of a subject string,
487            it does the same, unless a different locale has been set for the match
488            (using the /L modifier). In this case, it uses isprint() to decide.
490     4. Fixed a major bug that caused incorrect computation of the amount of memory
491        required for a compiled pattern when options that changed within the
492        pattern affected the logic of the preliminary scan that determines the
493        length. The relevant options are -x, and -i in UTF-8 mode. The result was
494        that the computed length was too small. The symptoms of this bug were
495        either the PCRE error "internal error: code overflow" from pcre_compile(),
496        or a glibc crash with a message such as "pcretest: free(): invalid next
497        size (fast)". Examples of patterns that provoked this bug (shown in
498        pcretest format) are:
500          /(?-x: )/x
501          /(?x)(?-x: \s*#\s*)/
502          /((?i)[\x{c0}])/8
503          /(?i:[\x{c0}])/8
505        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
506        is now done differently.
508     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
509        wrapper classes; (b) implement a new function in the C++ scanner that is
510        more efficient than the old way of doing things because it avoids levels of
511        recursion in the regex matching; (c) add a paragraph to the documentation
512        for the FullMatch() function.
514     6. The escape sequence \n was being treated as whatever was defined as
515        "newline". Not only was this contrary to the documentation, which states
516        that \n is character 10 (hex 0A), but it also went horribly wrong when
517        "newline" was defined as CRLF. This has been fixed.
519     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
520        was being set to -1 for the "end of line" case (supposedly a value that no
521        character can have). Though this value is never used (the check for end of
522        line is "zero bytes in current character"), it caused compiler complaints.
523        I've changed it to 0xffffffff.
525     8. In pcre_version.c, the version string was being built by a sequence of
526        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
527        string (as it is for production releases) called a macro with an empty
528        argument. The C standard says the result of this is undefined. The gcc
529        compiler treats it as an empty string (which was what was wanted) but it is
530        reported that Visual C gives an error. The source has been hacked around to
531        avoid this problem.
533     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
534        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
535        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
536        of them did).
538    10. Originally, pcretest opened its input and output without "b"; then I was
539        told that "b" was needed in some environments, so it was added for release
540        5.0 to both the input and output. (It makes no difference on Unix-like
541        systems.) Later I was told that it is wrong for the input on Windows. I've
542        now abstracted the modes into two macros, to make it easier to fiddle with
543        them, and removed "b" from the input mode under Windows.
545    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
547    12. Added -help and --help to pcretest as an official way of being reminded
548        of the options.
550    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
551        and pcrecpp.cc because they annoy compilers at high warning levels.
553    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
555    15. Fixed an occurrence of == in configure.ac that should have been = (shell
556        scripts are not C programs :-) and which was not noticed because it works
557        on Linux.
559    16. pcretest is supposed to handle any length of pattern and data line (as one
560        line or as a continued sequence of lines) by extending its input buffer if
561        necessary. This feature was broken for very long pattern lines, leading to
562        a string of junk being passed to pcre_compile() if the pattern was longer
563        than about 50K.
565    17. I have done a major re-factoring of the way pcre_compile() computes the
566        amount of memory needed for a compiled pattern. Previously, there was code
567        that made a preliminary scan of the pattern in order to do this. That was
568        OK when PCRE was new, but as the facilities have expanded, it has become
569        harder and harder to keep it in step with the real compile phase, and there
570        have been a number of bugs (see for example, 4 above). I have now found a
571        cunning way of running the real compile function in a "fake" mode that
572        enables it to compute how much memory it would need, while actually only
573        ever using a few hundred bytes of working memory and without too many
574        tests of the mode. This should make future maintenance and development
575        easier. A side effect of this work is that the limit of 200 on the nesting
576        depth of parentheses has been removed (though this was never a serious
577        limitation, I suspect). However, there is a downside: pcre_compile() now
578        runs more slowly than before (30% or more, depending on the pattern). I
579        hope this isn't a big issue. There is no effect on runtime performance.
581    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
582        newline (only possible for the last line of a file) and it was a
583        pattern that set a locale (followed by /Lsomething), pcretest crashed.
585    19. Added additional timing features to pcretest. (1) The -tm option now times
586        matching only, not compiling. (2) Both -t and -tm can be followed, as a
587        separate command line item, by a number that specifies the number of
588        repeats to use when timing. The default is 50000; this gives better
589        precision, but takes uncomfortably long for very large patterns.
591    20. Extended pcre_study() to be more clever in cases where a branch of a
592        subpattern has no definite first character. For example, (a*|b*)[cd] would
593        previously give no result from pcre_study(). Now it recognizes that the
594        first character must be a, b, c, or d.
596    21. There was an incorrect error "recursive call could loop indefinitely" if
597        a subpattern (or the entire pattern) that was being tested for matching an
598        empty string contained only one non-empty item after a nested subpattern.
599        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
600        incorrectly, because the \d was being skipped in the check.
602    22. The pcretest program now has a new pattern option /B and a command line
603        option -b, which is equivalent to adding /B to every pattern. This causes
604        it to show the compiled bytecode, without the additional information that
605        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
606        is the same as /B/I).
608    23. A new optimization is now able automatically to treat some sequences such
609        as a*b as a*+b. More specifically, if something simple (such as a character
610        or a simple class like \d) has an unlimited quantifier, and is followed by
611        something that cannot possibly match the quantified thing, the quantifier
612        is automatically "possessified".
614    24. A recursive reference to a subpattern whose number was greater than 39
615        went wrong under certain circumstances in UTF-8 mode. This bug could also
616        have affected the operation of pcre_study().
618    25. Realized that a little bit of performance could be had by replacing
619        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
621    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
623    27. Possessive quantifiers such as a++ were previously implemented by turning
624        them into atomic groups such as ($>a+). Now they have their own opcodes,
625        which improves performance. This includes the automatically created ones
626        from 23 above.
628    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
629        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
630        the first matched character to be a colon. This applied both to named and
631        numbered groups.
633    29. The ucpinternal.h header file was missing its idempotency #ifdef.
635    30. I was sent a "project" file called libpcre.a.dev which I understand makes
636        building PCRE on Windows easier, so I have included it in the distribution.
638    31. There is now a check in pcretest against a ridiculously large number being
639        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
640        loop, the loop is abandoned.
642    32. Forward references to subpatterns in conditions such as (?(2)...) where
643        subpattern 2 is defined later cause pcre_compile() to search forwards in
644        the pattern for the relevant set of parentheses. This search went wrong
645        when there were unescaped parentheses in a character class, parentheses
646        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
648    33. "Subroutine" calls and backreferences were previously restricted to
649        referencing subpatterns earlier in the regex. This restriction has now
650        been removed.
652    34. Added a number of extra features that are going to be in Perl 5.10. On the
653        whole, these are just syntactic alternatives for features that PCRE had
654        previously implemented using the Python syntax or my own invention. The
655        other formats are all retained for compatibility.
657        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
658            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
659            also .NET compatible.
661        (b) A recursion or subroutine call to a named group can now be defined as
662            (?&name) as well as (?P>name).
664        (c) A backreference to a named group can now be defined as \k<name> or
665            \k'name' as well as (?P=name). The new forms, as well as being in Perl
666            5.10, are also .NET compatible.
668        (d) A conditional reference to a named group can now use the syntax
669            (?(<name>) or (?('name') as well as (?(name).
671        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
672            groups (named and numbered) that are never evaluated inline, but can be
673            called as "subroutines" from elsewhere. In effect, the DEFINE condition
674            is always false. There may be only one alternative in such a group.
676        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
677            as the simple (?(R). The condition is true only if the most recent
678            recursion is that of the given number or name. It does not search out
679            through the entire recursion stack.
681        (g) The escape \gN or \g{N} has been added, where N is a positive or
682            negative number, specifying an absolute or relative reference.
684    35. Tidied to get rid of some further signed/unsigned compiler warnings and
685        some "unreachable code" warnings.
687    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
688        things, this adds five new scripts.
690    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
691        There were also incompatibilities regarding the handling of \Q..\E inside
692        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
693        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
695    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
696        matches an empty string, and forcibly breaks the loop. There were bugs in
697        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
698        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
699        separate and independent bugs (that affected different cases) have been
700        fixed.
702    39. Refactored the code to abolish the use of different opcodes for small
703        capturing bracket numbers. This is a tidy that I avoided doing when I
704        removed the limit on the number of capturing brackets for 3.5 back in 2001.
705        The new approach is not only tidier, it makes it possible to reduce the
706        memory needed to fix the previous bug (38).
708    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
709        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
710        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
711        mode.
713    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
714        report.
716    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
717        copy construction and assignment in the C++ wrapper.
719    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
720        couple of bugs that could have given wrong results in the "--newline=crlf"
721        case.
723    44. Added a number of casts and did some reorganization of signed/unsigned int
724        variables following suggestions from Dair Grant. Also renamed the variable
725        "this" as "item" because it is a C++ keyword.
727    45. Arranged for dftables to add
729          #include "pcre_internal.h"
731        to pcre_chartables.c because without it, gcc 4.x may remove the array
732        definition from the final binary if PCRE is built into a static library and
733        dead code stripping is activated.
735    46. For an unanchored pattern, if a match attempt fails at the start of a
736        newline sequence, and the newline setting is CRLF or ANY, and the next two
737        characters are CRLF, advance by two characters instead of one.
740    Version 6.7 04-Jul-06
741    ---------------------
743     1. In order to handle tests when input lines are enormously long, pcretest has
744        been re-factored so that it automatically extends its buffers when
745        necessary. The code is crude, but this _is_ just a test program. The
746        default size has been increased from 32K to 50K.
748     2. The code in pcre_study() was using the value of the re argument before
749        testing it for NULL. (Of course, in any sensible call of the function, it
750        won't be NULL.)
752     3. The memmove() emulation function in pcre_internal.h, which is used on
753        systems that lack both memmove() and bcopy() - that is, hardly ever -
754        was missing a "static" storage class specifier.
756     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
757        containing an extended class (one that cannot be represented by a bitmap
758        because it contains high-valued characters or Unicode property items, e.g.
759        [\pZ]). Almost always one would set UTF-8 mode when processing such a
760        pattern, but PCRE should not loop if you do not (it no longer does).
761        [Detail: two cases were found: (a) a repeated subpattern containing an
762        extended class; (b) a recursive reference to a subpattern that followed a
763        previous extended class. It wasn't skipping over the extended class
764        correctly when UTF-8 mode was not set.]
766     5. A negated single-character class was not being recognized as fixed-length
767        in lookbehind assertions such as (?<=[^f]), leading to an incorrect
768        compile error "lookbehind assertion is not fixed length".
770     6. The RunPerlTest auxiliary script was showing an unexpected difference
771        between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
772        write a Perl script that can interpret lines of an input file either as
773        byte characters or as UTF-8, which is what "perltest" was being required to
774        do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
775        can't do is switch easily at run time between having the "use utf8;" pragma
776        or not. In the end, I fudged it by using the RunPerlTest script to insert
777        "use utf8;" explicitly for the UTF-8 tests.
779     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
780        the end of the subject string, contrary to the documentation and to what
781        Perl does. This was true of both matching functions. Now it matches only at
782        the start of the subject and immediately after *internal* newlines.
784     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
785        a pointer to an int instead of a pointer to an unsigned long int. This
786        caused problems on 64-bit systems.
788     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
789        instance of the 'standard' template library not being so standard".
791    10. There was no check on the number of named subpatterns nor the maximum
792        length of a subpattern name. The product of these values is used to compute
793        the size of the memory block for a compiled pattern. By supplying a very
794        long subpattern name and a large number of named subpatterns, the size
795        computation could be caused to overflow. This is now prevented by limiting
796        the length of names to 32 characters, and the number of named subpatterns
797        to 10,000.
799    11. Subpatterns that are repeated with specific counts have to be replicated in
800        the compiled pattern. The size of memory for this was computed from the
801        length of the subpattern and the repeat count. The latter is limited to
802        65535, but there was no limit on the former, meaning that integer overflow
803        could in principle occur. The compiled length of a repeated subpattern is
804        now limited to 30,000 bytes in order to prevent this.
806    12. Added the optional facility to have named substrings with the same name.
808    13. Added the ability to use a named substring as a condition, using the
809        Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
810        are numbers (not recommended). Forward references are permitted.
812    14. Added forward references in named backreferences (if you see what I mean).
814    15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
815        pattern could run off the end of the subject. For example, the pattern
816        "(?s)(.{1,5})"8 did this with the subject "ab".
818    16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
819        PCRE_CASELESS was set when matching characters that were quantified with ?
820        or *.
822    17. A character class other than a single negated character that had a minimum
823        but no maximum quantifier - for example [ab]{6,} - was not handled
824        correctly by pce_dfa_exec(). It would match only one character.
826    18. A valid (though odd) pattern that looked like a POSIX character
827        class but used an invalid character after [ (for example [[,abc,]]) caused
828        pcre_compile() to give the error "Failed: internal error: code overflow" or
829        in some cases to crash with a glibc free() error. This could even happen if
830        the pattern terminated after [[ but there just happened to be a sequence of
831        letters, a binary zero, and a closing ] in the memory that followed.
833    19. Perl's treatment of octal escapes in the range \400 to \777 has changed
834        over the years. Originally (before any Unicode support), just the bottom 8
835        bits were taken. Thus, for example, \500 really meant \100. Nowadays the
836        output from "man perlunicode" includes this:
838          The regular expression compiler produces polymorphic opcodes.  That
839          is, the pattern adapts to the data and automatically switches to
840          the Unicode character scheme when presented with Unicode data--or
841          instead uses a traditional byte scheme when presented with byte
842          data.
844        Sadly, a wide octal escape does not cause a switch, and in a string with
845        no other multibyte characters, these octal escapes are treated as before.
846        Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
847        /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
848        Unicode string.
850        I have not perpetrated such confusion in PCRE. Up till now, it took just
851        the bottom 8 bits, as in old Perl. I have now made octal escapes with
852        values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
853        translate to the appropriate multibyte character.
855    29. Applied some refactoring to reduce the number of warnings from Microsoft
856        and Borland compilers. This has included removing the fudge introduced
857        seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
858        a warning about an unused variable.
860    21. PCRE has not included VT (character 0x0b) in the set of whitespace
861        characters since release 4.0, because Perl (from release 5.004) does not.
862        [Or at least, is documented not to: some releases seem to be in conflict
863        with the documentation.] However, when a pattern was studied with
864        pcre_study() and all its branches started with \s, PCRE still included VT
865        as a possible starting character. Of course, this did no harm; it just
866        caused an unnecessary match attempt.
868    22. Removed a now-redundant internal flag bit that recorded the fact that case
869        dependency changed within the pattern. This was once needed for "required
870        byte" processing, but is no longer used. This recovers a now-scarce options
871        bit. Also moved the least significant internal flag bit to the most-
872        significant bit of the word, which was not previously used (hangover from
873        the days when it was an int rather than a uint) to free up another bit for
874        the future.
876    23. Added support for CRLF line endings as well as CR and LF. As well as the
877        default being selectable at build time, it can now be changed at runtime
878        via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
879        specify that it is scanning data with non-default line endings.
881    24. Changed the definition of CXXLINK to make it agree with the definition of
882        LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
884    25. Applied Ian Taylor's patches to avoid using another stack frame for tail
885        recursions. This makes a big different to stack usage for some patterns.
887    26. If a subpattern containing a named recursion or subroutine reference such
888        as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
889        the space required for the compiled pattern went wrong and gave too small a
890        value. Depending on the environment, this could lead to "Failed: internal
891        error: code overflow at offset 49" or "glibc detected double free or
892        corruption" errors.
894    27. Applied patches from Google (a) to support the new newline modes and (b) to
895        advance over multibyte UTF-8 characters in GlobalReplace.
897    28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
898        difference for some implementation of PCRE in some Windows version.
900    29. Added some extra testing facilities to pcretest:
902        \q<number>   in a data line sets the "match limit" value
903        \Q<number>   in a data line sets the "match recursion limt" value
904        -S <number>  sets the stack size, where <number> is in megabytes
906        The -S option isn't available for Windows.
909    Version 6.6 06-Feb-06
910    ---------------------
912     1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
913        in pcreposix.h. I have copied the definition from pcre.h.
915     2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
916        because pcre.h is no longer a built file.
918     3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
919        not normally included in the compiled code.
922    Version 6.5 01-Feb-06
923    ---------------------
925     1. When using the partial match feature with pcre_dfa_exec(), it was not
926        anchoring the second and subsequent partial matches at the new starting
927        point. This could lead to incorrect results. For example, with the pattern
928        /1234/, partially matching against "123" and then "a4" gave a match.
930     2. Changes to pcregrep:
932        (a) All non-match returns from pcre_exec() were being treated as failures
933            to match the line. Now, unless the error is PCRE_ERROR_NOMATCH, an
934            error message is output. Some extra information is given for the
935            PCRE_ERROR_MATCHLIMIT and PCRE_ERROR_RECURSIONLIMIT errors, which are
936            probably the only errors that are likely to be caused by users (by
937            specifying a regex that has nested indefinite repeats, for instance).
938            If there are more than 20 of these errors, pcregrep is abandoned.
940        (b) A binary zero was treated as data while matching, but terminated the
941            output line if it was written out. This has been fixed: binary zeroes
942            are now no different to any other data bytes.
944        (c) Whichever of the LC_ALL or LC_CTYPE environment variables is set is
945            used to set a locale for matching. The --locale=xxxx long option has
946            been added (no short equivalent) to specify a locale explicitly on the
947            pcregrep command, overriding the environment variables.
949        (d) When -B was used with -n, some line numbers in the output were one less
950            than they should have been.
952        (e) Added the -o (--only-matching) option.
954        (f) If -A or -C was used with -c (count only), some lines of context were
955            accidentally printed for the final match.
957        (g) Added the -H (--with-filename) option.
959        (h) The combination of options -rh failed to suppress file names for files
960            that were found from directory arguments.
962        (i) Added the -D (--devices) and -d (--directories) options.
964        (j) Added the -F (--fixed-strings) option.
966        (k) Allow "-" to be used as a file name for -f as well as for a data file.
968        (l) Added the --colo(u)r option.
970        (m) Added Jeffrey Friedl's -S testing option, but within #ifdefs so that it
971            is not present by default.
973     3. A nasty bug was discovered in the handling of recursive patterns, that is,
974        items such as (?R) or (?1), when the recursion could match a number of
975        alternatives. If it matched one of the alternatives, but subsequently,
976        outside the recursion, there was a failure, the code tried to back up into
977        the recursion. However, because of the way PCRE is implemented, this is not
978        possible, and the result was an incorrect result from the match.
980        In order to prevent this happening, the specification of recursion has
981        been changed so that all such subpatterns are automatically treated as
982        atomic groups. Thus, for example, (?R) is treated as if it were (?>(?R)).
984     4. I had overlooked the fact that, in some locales, there are characters for
985        which isalpha() is true but neither isupper() nor islower() are true. In
986        the fr_FR locale, for instance, the \xAA and \xBA characters (ordmasculine
987        and ordfeminine) are like this. This affected the treatment of \w and \W
988        when they appeared in character classes, but not when they appeared outside
989        a character class. The bit map for "word" characters is now created
990        separately from the results of isalnum() instead of just taking it from the
991        upper, lower, and digit maps. (Plus the underscore character, of course.)
993     5. The above bug also affected the handling of POSIX character classes such as
994        [[:alpha:]] and [[:alnum:]]. These do not have their own bit maps in PCRE's
995        permanent tables. Instead, the bit maps for such a class were previously
996        created as the appropriate unions of the upper, lower, and digit bitmaps.
997        Now they are created by subtraction from the [[:word:]] class, which has
998        its own bitmap.
1000     6. The [[:blank:]] character class matches horizontal, but not vertical space.
1001        It is created by subtracting the vertical space characters (\x09, \x0a,
1002        \x0b, \x0c) from the [[:space:]] bitmap. Previously, however, the
1003        subtraction was done in the overall bitmap for a character class, meaning
1004        that a class such as [\x0c[:blank:]] was incorrect because \x0c would not
1005        be recognized. This bug has been fixed.
1007     7. Patches from the folks at Google:
1009          (a) pcrecpp.cc: "to handle a corner case that may or may not happen in
1010          real life, but is still worth protecting against".
1012          (b) pcrecpp.cc: "corrects a bug when negative radixes are used with
1013          regular expressions".
1015          (c) pcre_scanner.cc: avoid use of std::count() because not all systems
1016          have it.
1018          (d) Split off pcrecpparg.h from pcrecpp.h and had the former built by
1019          "configure" and the latter not, in order to fix a problem somebody had
1020          with compiling the Arg class on HP-UX.
1022          (e) Improve the error-handling of the C++ wrapper a little bit.
1024          (f) New tests for checking recursion limiting.
1026     8. The pcre_memmove() function, which is used only if the environment does not
1027        have a standard memmove() function (and is therefore rarely compiled),
1028        contained two bugs: (a) use of int instead of size_t, and (b) it was not
1029        returning a result (though PCRE never actually uses the result).
1031     9. In the POSIX regexec() interface, if nmatch is specified as a ridiculously
1032        large number - greater than INT_MAX/(3*sizeof(int)) - REG_ESPACE is
1033        returned instead of calling malloc() with an overflowing number that would
1034        most likely cause subsequent chaos.
1036    10. The debugging option of pcretest was not showing the NO_AUTO_CAPTURE flag.
1038    11. The POSIX flag REG_NOSUB is now supported. When a pattern that was compiled
1039        with this option is matched, the nmatch and pmatch options of regexec() are
1040        ignored.
1042    12. Added REG_UTF8 to the POSIX interface. This is not defined by POSIX, but is
1043        provided in case anyone wants to the the POSIX interface with UTF-8
1044        strings.
1046    13. Added CXXLDFLAGS to the Makefile parameters to provide settings only on the
1047        C++ linking (needed for some HP-UX environments).
1049    14. Avoid compiler warnings in get_ucpname() when compiled without UCP support
1050        (unused parameter) and in the pcre_printint() function (omitted "default"
1051        switch label when the default is to do nothing).
1053    15. Added some code to make it possible, when PCRE is compiled as a C++
1054        library, to replace subject pointers for pcre_exec() with a smart pointer
1055        class, thus making it possible to process discontinuous strings.
1057    16. The two macros PCRE_EXPORT and PCRE_DATA_SCOPE are confusing, and perform
1058        much the same function. They were added by different people who were trying
1059        to make PCRE easy to compile on non-Unix systems. It has been suggested
1060        that PCRE_EXPORT be abolished now that there is more automatic apparatus
1061        for compiling on Windows systems. I have therefore replaced it with
1062        PCRE_DATA_SCOPE. This is set automatically for Windows; if not set it
1063        defaults to "extern" for C or "extern C" for C++, which works fine on
1064        Unix-like systems. It is now possible to override the value of PCRE_DATA_
1065        SCOPE with something explicit in config.h. In addition:
1067        (a) pcreposix.h still had just "extern" instead of either of these macros;
1068            I have replaced it with PCRE_DATA_SCOPE.
1070        (b) Functions such as _pcre_xclass(), which are internal to the library,
1071            but external in the C sense, all had PCRE_EXPORT in their definitions.
1072            This is apparently wrong for the Windows case, so I have removed it.
1073            (It makes no difference on Unix-like systems.)
1075    17. Added a new limit, MATCH_LIMIT_RECURSION, which limits the depth of nesting
1076        of recursive calls to match(). This is different to MATCH_LIMIT because
1077        that limits the total number of calls to match(), not all of which increase
1078        the depth of recursion. Limiting the recursion depth limits the amount of
1079        stack (or heap if NO_RECURSE is set) that is used. The default can be set
1080        when PCRE is compiled, and changed at run time. A patch from Google adds
1081        this functionality to the C++ interface.
1083    18. Changes to the handling of Unicode character properties:
1085        (a) Updated the table to Unicode 4.1.0.
1087        (b) Recognize characters that are not in the table as "Cn" (undefined).
1089        (c) I revised the way the table is implemented to a much improved format
1090            which includes recognition of ranges. It now supports the ranges that
1091            are defined in UnicodeData.txt, and it also amalgamates other
1092            characters into ranges. This has reduced the number of entries in the
1093            table from around 16,000 to around 3,000, thus reducing its size
1094            considerably. I realized I did not need to use a tree structure after
1095            all - a binary chop search is just as efficient. Having reduced the
1096            number of entries, I extended their size from 6 bytes to 8 bytes to
1097            allow for more data.
1099        (d) Added support for Unicode script names via properties such as \p{Han}.
1101    19. In UTF-8 mode, a backslash followed by a non-Ascii character was not
1102        matching that character.
1104    20. When matching a repeated Unicode property with a minimum greater than zero,
1105        (for example \pL{2,}), PCRE could look past the end of the subject if it
1106        reached it while seeking the minimum number of characters. This could
1107        happen only if some of the characters were more than one byte long, because
1108        there is a check for at least the minimum number of bytes.
1110    21. Refactored the implementation of \p and \P so as to be more general, to
1111        allow for more different types of property in future. This has changed the
1112        compiled form incompatibly. Anybody with saved compiled patterns that use
1113        \p or \P will have to recompile them.
1115    22. Added "Any" and "L&" to the supported property types.
1117    23. Recognize \x{...} as a code point specifier, even when not in UTF-8 mode,
1118        but give a compile time error if the value is greater than 0xff.
1120    24. The man pages for pcrepartial, pcreprecompile, and pcre_compile2 were
1121        accidentally not being installed or uninstalled.
1123    25. The pcre.h file was built from pcre.h.in, but the only changes that were
1124        made were to insert the current release number. This seemed silly, because
1125        it made things harder for people building PCRE on systems that don't run
1126        "configure". I have turned pcre.h into a distributed file, no longer built
1127        by "configure", with the version identification directly included. There is
1128        no longer a pcre.h.in file.
1130        However, this change necessitated a change to the pcre-config script as
1131        well. It is built from pcre-config.in, and one of the substitutions was the
1132        release number. I have updated configure.ac so that ./configure now finds
1133        the release number by grepping pcre.h.
1135    26. Added the ability to run the tests under valgrind.
1138    Version 6.4 05-Sep-05
1139    ---------------------
1141     1. Change 6.0/10/(l) to pcregrep introduced a bug that caused separator lines
1142        "--" to be printed when multiple files were scanned, even when none of the
1143        -A, -B, or -C options were used. This is not compatible with Gnu grep, so I
1144        consider it to be a bug, and have restored the previous behaviour.
1146     2. A couple of code tidies to get rid of compiler warnings.
1148     3. The pcretest program used to cheat by referring to symbols in the library
1149        whose names begin with _pcre_. These are internal symbols that are not
1150        really supposed to be visible externally, and in some environments it is
1151        possible to suppress them. The cheating is now confined to including
1152        certain files from the library's source, which is a bit cleaner.
1154     4. Renamed pcre.in as pcre.h.in to go with pcrecpp.h.in; it also makes the
1155        file's purpose clearer.
1157     5. Reorganized pcre_ucp_findchar().
1160    Version 6.3 15-Aug-05
1161    ---------------------
1163     1. The file libpcre.pc.in did not have general read permission in the tarball.
1165     2. There were some problems when building without C++ support:
1167        (a) If C++ support was not built, "make install" and "make test" still
1168            tried to test it.
1170        (b) There were problems when the value of CXX was explicitly set. Some
1171            changes have been made to try to fix these, and ...
1173        (c) --disable-cpp can now be used to explicitly disable C++ support.
1175        (d) The use of @CPP_OBJ@ directly caused a blank line preceded by a
1176            backslash in a target when C++ was disabled. This confuses some
1177            versions of "make", apparently. Using an intermediate variable solves
1178            this. (Same for CPP_LOBJ.)
1180     3. $(LINK_FOR_BUILD) now includes $(CFLAGS_FOR_BUILD) and $(LINK)
1181        (non-Windows) now includes $(CFLAGS) because these flags are sometimes
1182        necessary on certain architectures.
1184     4. Added a setting of -export-symbols-regex to the link command to remove
1185        those symbols that are exported in the C sense, but actually are local
1186        within the library, and not documented. Their names all begin with
1187        "_pcre_". This is not a perfect job, because (a) we have to except some
1188        symbols that pcretest ("illegally") uses, and (b) the facility isn't always
1189        available (and never for static libraries). I have made a note to try to
1190        find a way round (a) in the future.
1193    Version 6.2 01-Aug-05
1194    ---------------------
1196     1. There was no test for integer overflow of quantifier values. A construction
1197        such as {1111111111111111} would give undefined results. What is worse, if
1198        a minimum quantifier for a parenthesized subpattern overflowed and became
1199        negative, the calculation of the memory size went wrong. This could have
1200        led to memory overwriting.
1202     2. Building PCRE using VPATH was broken. Hopefully it is now fixed.
1204     3. Added "b" to the 2nd argument of fopen() in dftables.c, for non-Unix-like
1205        operating environments where this matters.
1207     4. Applied Giuseppe Maxia's patch to add additional features for controlling
1208        PCRE options from within the C++ wrapper.
1210     5. Named capturing subpatterns were not being correctly counted when a pattern
1211        was compiled. This caused two problems: (a) If there were more than 100
1212        such subpatterns, the calculation of the memory needed for the whole
1213        compiled pattern went wrong, leading to an overflow error. (b) Numerical
1214        back references of the form \12, where the number was greater than 9, were
1215        not recognized as back references, even though there were sufficient
1216        previous subpatterns.
1218     6. Two minor patches to pcrecpp.cc in order to allow it to compile on older
1219        versions of gcc, e.g. 2.95.4.
1222    Version 6.1 21-Jun-05
1223    ---------------------
1225     1. There was one reference to the variable "posix" in pcretest.c that was not
1226        surrounded by "#if !defined NOPOSIX".
1228     2. Make it possible to compile pcretest without DFA support, UTF8 support, or
1229        the cross-check on the old pcre_info() function, for the benefit of the
1230        cut-down version of PCRE that is currently imported into Exim.
1232     3. A (silly) pattern starting with (?i)(?-i) caused an internal space
1233        allocation error. I've done the easy fix, which wastes 2 bytes for sensible
1234        patterns that start (?i) but I don't think that matters. The use of (?i) is
1235        just an example; this all applies to the other options as well.
1237     4. Since libtool seems to echo the compile commands it is issuing, the output
1238        from "make" can be reduced a bit by putting "@" in front of each libtool
1239        compile command.
1241     5. Patch from the folks at Google for configure.in to be a bit more thorough
1242        in checking for a suitable C++ installation before trying to compile the
1243        C++ stuff. This should fix a reported problem when a compiler was present,
1244        but no suitable headers.
1246     6. The man pages all had just "PCRE" as their title. I have changed them to
1247        be the relevant file name. I have also arranged that these names are
1248        retained in the file doc/pcre.txt, which is a concatenation in text format
1249        of all the man pages except the little individual ones for each function.
1251     7. The NON-UNIX-USE file had not been updated for the different set of source
1252        files that come with release 6. I also added a few comments about the C++
1253        wrapper.
1256    Version 6.0 07-Jun-05
1257    ---------------------
1259     1. Some minor internal re-organization to help with my DFA experiments.
1261     2. Some missing #ifdef SUPPORT_UCP conditionals in pcretest and printint that
1262        didn't matter for the library itself when fully configured, but did matter
1263        when compiling without UCP support, or within Exim, where the ucp files are
1264        not imported.
1266     3. Refactoring of the library code to split up the various functions into
1267        different source modules. The addition of the new DFA matching code (see
1268        below) to a single monolithic source would have made it really too
1269        unwieldy, quite apart from causing all the code to be include in a
1270        statically linked application, when only some functions are used. This is
1271        relevant even without the DFA addition now that patterns can be compiled in
1272        one application and matched in another.
1274        The downside of splitting up is that there have to be some external
1275        functions and data tables that are used internally in different modules of
1276        the library but which are not part of the API. These have all had their
1277        names changed to start with "_pcre_" so that they are unlikely to clash
1278        with other external names.
1280     4. Added an alternate matching function, pcre_dfa_exec(), which matches using
1281        a different (DFA) algorithm. Although it is slower than the original
1282        function, it does have some advantages for certain types of matching
1283        problem.
1285     5. Upgrades to pcretest in order to test the features of pcre_dfa_exec(),
1286        including restarting after a partial match.
1288     6. A patch for pcregrep that defines INVALID_FILE_ATTRIBUTES if it is not
1289        defined when compiling for Windows was sent to me. I have put it into the
1290        code, though I have no means of testing or verifying it.
1292     7. Added the pcre_refcount() auxiliary function.
1294     8. Added the PCRE_FIRSTLINE option. This constrains an unanchored pattern to
1295        match before or at the first newline in the subject string. In pcretest,
1296        the /f option on a pattern can be used to set this.
1298     9. A repeated \w when used in UTF-8 mode with characters greater than 256
1299        would behave wrongly. This has been present in PCRE since release 4.0.
1301    10. A number of changes to the pcregrep command:
1303        (a) Refactored how -x works; insert ^(...)$ instead of setting
1304            PCRE_ANCHORED and checking the length, in preparation for adding
1305            something similar for -w.
1307        (b) Added the -w (match as a word) option.
1309        (c) Refactored the way lines are read and buffered so as to have more
1310            than one at a time available.
1312        (d) Implemented a pcregrep test script.
1314        (e) Added the -M (multiline match) option. This allows patterns to match
1315            over several lines of the subject. The buffering ensures that at least
1316            8K, or the rest of the document (whichever is the shorter) is available
1317            for matching (and similarly the previous 8K for lookbehind assertions).
1319        (f) Changed the --help output so that it now says
1321              -w, --word-regex(p)
1323            instead of two lines, one with "regex" and the other with "regexp"
1324            because that confused at least one person since the short forms are the
1325            same. (This required a bit of code, as the output is generated
1326            automatically from a table. It wasn't just a text change.)
1328        (g) -- can be used to terminate pcregrep options if the next thing isn't an
1329            option but starts with a hyphen. Could be a pattern or a path name
1330            starting with a hyphen, for instance.
1332        (h) "-" can be given as a file name to represent stdin.
1334        (i) When file names are being printed, "(standard input)" is used for
1335            the standard input, for compatibility with GNU grep. Previously
1336            "<stdin>" was used.
1338        (j) The option --label=xxx can be used to supply a name to be used for
1339            stdin when file names are being printed. There is no short form.
1341        (k) Re-factored the options decoding logic because we are going to add
1342            two more options that take data. Such options can now be given in four
1343            different ways, e.g. "-fname", "-f name", "--file=name", "--file name".
1345        (l) Added the -A, -B, and -C options for requesting that lines of context
1346            around matches be printed.
1348        (m) Added the -L option to print the names of files that do not contain
1349            any matching lines, that is, the complement of -l.
1351        (n) The return code is 2 if any file cannot be opened, but pcregrep does
1352            continue to scan other files.
1354        (o) The -s option was incorrectly implemented. For compatibility with other
1355            greps, it now suppresses the error message for a non-existent or non-
1356            accessible file (but not the return code). There is a new option called
1357            -q that suppresses the output of matching lines, which was what -s was
1358            previously doing.
1360        (p) Added --include and --exclude options to specify files for inclusion
1361            and exclusion when recursing.
1363    11. The Makefile was not using the Autoconf-supported LDFLAGS macro properly.
1364        Hopefully, it now does.
1366    12. Missing cast in pcre_study().
1368    13. Added an "uninstall" target to the makefile.
1370    14. Replaced "extern" in the function prototypes in Makefile.in with
1371        "PCRE_DATA_SCOPE", which defaults to 'extern' or 'extern "C"' in the Unix
1372        world, but is set differently for Windows.
1374    15. Added a second compiling function called pcre_compile2(). The only
1375        difference is that it has an extra argument, which is a pointer to an
1376        integer error code. When there is a compile-time failure, this is set
1377        non-zero, in addition to the error test pointer being set to point to an
1378        error message. The new argument may be NULL if no error number is required
1379        (but then you may as well call pcre_compile(), which is now just a
1380        wrapper). This facility is provided because some applications need a
1381        numeric error indication, but it has also enabled me to tidy up the way
1382        compile-time errors are handled in the POSIX wrapper.
1384    16. Added VPATH=.libs to the makefile; this should help when building with one
1385        prefix path and installing with another. (Or so I'm told by someone who
1386        knows more about this stuff than I do.)
1388    17. Added a new option, REG_DOTALL, to the POSIX function regcomp(). This
1389        passes PCRE_DOTALL to the pcre_compile() function, making the "." character
1390        match everything, including newlines. This is not POSIX-compatible, but
1391        somebody wanted the feature. From pcretest it can be activated by using
1392        both the P and the s flags.
1394    18. AC_PROG_LIBTOOL appeared twice in Makefile.in. Removed one.
1396    19. libpcre.pc was being incorrectly installed as executable.
1398    20. A couple of places in pcretest check for end-of-line by looking for '\n';
1399        it now also looks for '\r' so that it will work unmodified on Windows.
1401    21. Added Google's contributed C++ wrapper to the distribution.
1403    22. Added some untidy missing memory free() calls in pcretest, to keep
1404        Electric Fence happy when testing.
1408    Version 5.0 13-Sep-04
1409    ---------------------
1411     1. Internal change: literal characters are no longer packed up into items
1412        containing multiple characters in a single byte-string. Each character
1413        is now matched using a separate opcode. However, there may be more than one
1414        byte in the character in UTF-8 mode.
1416     2. The pcre_callout_block structure has two new fields: pattern_position and
1417        next_item_length. These contain the offset in the pattern to the next match
1418        item, and its length, respectively.
1420     3. The PCRE_AUTO_CALLOUT option for pcre_compile() requests the automatic
1421        insertion of callouts before each pattern item. Added the /C option to
1422        pcretest to make use of this.
1424     4. On the advice of a Windows user, the lines
1426          #if defined(_WIN32) || defined(WIN32)
1427          _setmode( _fileno( stdout ), 0x8000 );
1428          #endif  /* defined(_WIN32) || defined(WIN32) */
1430        have been added to the source of pcretest. This apparently does useful
1431        magic in relation to line terminators.
1433     5. Changed "r" and "w" in the calls to fopen() in pcretest to "rb" and "wb"
1434        for the benefit of those environments where the "b" makes a difference.
1436     6. The icc compiler has the same options as gcc, but "configure" doesn't seem
1437        to know about it. I have put a hack into configure.in that adds in code
1438        to set GCC=yes if CC=icc. This seems to end up at a point in the
1439        generated configure script that is early enough to affect the setting of
1440        compiler options, which is what is needed, but I have no means of testing
1441        whether it really works. (The user who reported this had patched the
1442        generated configure script, which of course I cannot do.)
1444        LATER: After change 22 below (new libtool files), the configure script
1445        seems to know about icc (and also ecc). Therefore, I have commented out
1446        this hack in configure.in.
1448     7. Added support for pkg-config (2 patches were sent in).
1450     8. Negated POSIX character classes that used a combination of internal tables
1451        were completely broken. These were [[:^alpha:]], [[:^alnum:]], and
1452        [[:^ascii]]. Typically, they would match almost any characters. The other
1453        POSIX classes were not broken in this way.
1455     9. Matching the pattern "\b.*?" against "ab cd", starting at offset 1, failed
1456        to find the match, as PCRE was deluded into thinking that the match had to
1457        start at the start point or following a newline. The same bug applied to
1458        patterns with negative forward assertions or any backward assertions
1459        preceding ".*" at the start, unless the pattern required a fixed first
1460        character. This was a failing pattern: "(?!.bcd).*". The bug is now fixed.
1462    10. In UTF-8 mode, when moving forwards in the subject after a failed match
1463        starting at the last subject character, bytes beyond the end of the subject
1464        string were read.
1466    11. Renamed the variable "class" as "classbits" to make life easier for C++
1467        users. (Previously there was a macro definition, but it apparently wasn't
1468        enough.)
1470    12. Added the new field "tables" to the extra data so that tables can be passed
1471        in at exec time, or the internal tables can be re-selected. This allows
1472        a compiled regex to be saved and re-used at a later time by a different
1473        program that might have everything at different addresses.
1475    13. Modified the pcre-config script so that, when run on Solaris, it shows a
1476        -R library as well as a -L library.
1478    14. The debugging options of pcretest (-d on the command line or D on a
1479        pattern) showed incorrect output for anything following an extended class
1480        that contained multibyte characters and which was followed by a quantifier.
1482    15. Added optional support for general category Unicode character properties
1483        via the \p, \P, and \X escapes. Unicode property support implies UTF-8
1484        support. It adds about 90K to the size of the library. The meanings of the
1485        inbuilt class escapes such as \d and \s have NOT been changed.
1487    16. Updated pcredemo.c to include calls to free() to release the memory for the
1488        compiled pattern.
1490    17. The generated file chartables.c was being created in the source directory
1491        instead of in the building directory. This caused the build to fail if the
1492        source directory was different from the building directory, and was
1493        read-only.
1495    18. Added some sample Win commands from Mark Tetrode into the NON-UNIX-USE
1496        file. No doubt somebody will tell me if they don't make sense... Also added
1497        Dan Mooney's comments about building on OpenVMS.
1499    19. Added support for partial matching via the PCRE_PARTIAL option for
1500        pcre_exec() and the \P data escape in pcretest.
1502    20. Extended pcretest with 3 new pattern features:
1504        (i)   A pattern option of the form ">rest-of-line" causes pcretest to
1505              write the compiled pattern to the file whose name is "rest-of-line".
1506              This is a straight binary dump of the data, with the saved pointer to
1507              the character tables forced to be NULL. The study data, if any, is
1508              written too. After writing, pcretest reads a new pattern.
1510        (ii)  If, instead of a pattern, "<rest-of-line" is given, pcretest reads a
1511              compiled pattern from the given file. There must not be any
1512              occurrences of "<" in the file name (pretty unlikely); if there are,
1513              pcretest will instead treat the initial "<" as a pattern delimiter.
1514              After reading in the pattern, pcretest goes on to read data lines as
1515              usual.
1517        (iii) The F pattern option causes pcretest to flip the bytes in the 32-bit
1518              and 16-bit fields in a compiled pattern, to simulate a pattern that
1519              was compiled on a host of opposite endianness.
1521    21. The pcre-exec() function can now cope with patterns that were compiled on
1522        hosts of opposite endianness, with this restriction:
1524          As for any compiled expression that is saved and used later, the tables
1525          pointer field cannot be preserved; the extra_data field in the arguments
1526          to pcre_exec() should be used to pass in a tables address if a value
1527          other than the default internal tables were used at compile time.
1529    22. Calling pcre_exec() with a negative value of the "ovecsize" parameter is
1530        now diagnosed as an error. Previously, most of the time, a negative number
1531        would have been treated as zero, but if in addition "ovector" was passed as
1532        NULL, a crash could occur.
1534    23. Updated the files ltmain.sh, config.sub, config.guess, and aclocal.m4 with
1535        new versions from the libtool 1.5 distribution (the last one is a copy of
1536        a file called libtool.m4). This seems to have fixed the need to patch
1537        "configure" to support Darwin 1.3 (which I used to do). However, I still
1538        had to patch ltmain.sh to ensure that ${SED} is set (it isn't on my
1539        workstation).
1541    24. Changed the PCRE licence to be the more standard "BSD" licence.
1544    Version 4.5 01-Dec-03
1545    ---------------------
1547     1. There has been some re-arrangement of the code for the match() function so
1548        that it can be compiled in a version that does not call itself recursively.
1549        Instead, it keeps those local variables that need separate instances for
1550        each "recursion" in a frame on the heap, and gets/frees frames whenever it
1551        needs to "recurse". Keeping track of where control must go is done by means
1552        of setjmp/longjmp. The whole thing is implemented by a set of macros that
1553        hide most of the details from the main code, and operates only if
1554        NO_RECURSE is defined while compiling pcre.c. If PCRE is built using the
1555        "configure" mechanism, "--disable-stack-for-recursion" turns on this way of
1556        operating.
1558        To make it easier for callers to provide specially tailored get/free
1559        functions for this usage, two new functions, pcre_stack_malloc, and
1560        pcre_stack_free, are used. They are always called in strict stacking order,
1561        and the size of block requested is always the same.
1563        The PCRE_CONFIG_STACKRECURSE info parameter can be used to find out whether
1564        PCRE has been compiled to use the stack or the heap for recursion. The
1565        -C option of pcretest uses this to show which version is compiled.
1567        A new data escape \S, is added to pcretest; it causes the amounts of store
1568        obtained and freed by both kinds of malloc/free at match time to be added
1569        to the output.
1571     2. Changed the locale test to use "fr_FR" instead of "fr" because that's
1572        what's available on my current Linux desktop machine.
1574     3. When matching a UTF-8 string, the test for a valid string at the start has
1575        been extended. If start_offset is not zero, PCRE now checks that it points
1576        to a byte that is the start of a UTF-8 character. If not, it returns
1577        PCRE_ERROR_BADUTF8_OFFSET (-11). Note: the whole string is still checked;
1578        this is necessary because there may be backward assertions in the pattern.
1579        When matching the same subject several times, it may save resources to use
1580        PCRE_NO_UTF8_CHECK on all but the first call if the string is long.
1582     4. The code for checking the validity of UTF-8 strings has been tightened so
1583        that it rejects (a) strings containing 0xfe or 0xff bytes and (b) strings
1584        containing "overlong sequences".
1586     5. Fixed a bug (appearing twice) that I could not find any way of exploiting!
1587        I had written "if ((digitab[*p++] && chtab_digit) == 0)" where the "&&"
1588        should have been "&", but it just so happened that all the cases this let
1589        through by mistake were picked up later in the function.
1591     6. I had used a variable called "isblank" - this is a C99 function, causing
1592        some compilers to warn. To avoid this, I renamed it (as "blankclass").
1594     7. Cosmetic: (a) only output another newline at the end of pcretest if it is
1595        prompting; (b) run "./pcretest /dev/null" at the start of the test script
1596        so the version is shown; (c) stop "make test" echoing "./RunTest".
1598     8. Added patches from David Burgess to enable PCRE to run on EBCDIC systems.
1600     9. The prototype for memmove() for systems that don't have it was using
1601        size_t, but the inclusion of the header that defines size_t was later. I've
1602        moved the #includes for the C headers earlier to avoid this.
1604    10. Added some adjustments to the code to make it easier to compiler on certain
1605        special systems:
1607          (a) Some "const" qualifiers were missing.
1608          (b) Added the macro EXPORT before all exported functions; by default this
1609              is defined to be empty.
1610          (c) Changed the dftables auxiliary program (that builds chartables.c) so
1611              that it reads its output file name as an argument instead of writing
1612              to the standard output and assuming this can be redirected.
1614    11. In UTF-8 mode, if a recursive reference (e.g. (?1)) followed a character
1615        class containing characters with values greater than 255, PCRE compilation
1616        went into a loop.
1618    12. A recursive reference to a subpattern that was within another subpattern
1619        that had a minimum quantifier of zero caused PCRE to crash. For example,
1620        (x(y(?2))z)? provoked this bug with a subject that got as far as the
1621        recursion. If the recursively-called subpattern itself had a zero repeat,
1622        that was OK.
1624    13. In pcretest, the buffer for reading a data line was set at 30K, but the
1625        buffer into which it was copied (for escape processing) was still set at
1626        1024, so long lines caused crashes.
1628    14. A pattern such as /[ab]{1,3}+/ failed to compile, giving the error
1629        "internal error: code overflow...". This applied to any character class
1630        that was followed by a possessive quantifier.
1632    15. Modified the Makefile to add libpcre.la as a prerequisite for
1633        libpcreposix.la because I was told this is needed for a parallel build to
1634        work.
1636    16. If a pattern that contained .* following optional items at the start was
1637        studied, the wrong optimizing data was generated, leading to matching
1638        errors. For example, studying /[ab]*.*c/ concluded, erroneously, that any
1639        matching string must start with a or b or c. The correct conclusion for
1640        this pattern is that a match can start with any character.
1643    Version 4.4 13-Aug-03
1644    ---------------------
1646     1. In UTF-8 mode, a character class containing characters with values between
1647        127 and 255 was not handled correctly if the compiled pattern was studied.
1648        In fixing this, I have also improved the studying algorithm for such
1649        classes (slightly).
1651     2. Three internal functions had redundant arguments passed to them. Removal
1652        might give a very teeny performance improvement.
1654     3. Documentation bug: the value of the capture_top field in a callout is *one
1655        more than* the number of the hightest numbered captured substring.
1657     4. The Makefile linked pcretest and pcregrep with -lpcre, which could result
1658        in incorrectly linking with a previously installed version. They now link
1659        explicitly with libpcre.la.
1661     5. configure.in no longer needs to recognize Cygwin specially.
1663     6. A problem in pcre.in for Windows platforms is fixed.
1665     7. If a pattern was successfully studied, and the -d (or /D) flag was given to
1666        pcretest, it used to include the size of the study block as part of its
1667        output. Unfortunately, the structure contains a field that has a different
1668        size on different hardware architectures. This meant that the tests that
1669        showed this size failed. As the block is currently always of a fixed size,
1670        this information isn't actually particularly useful in pcretest output, so
1671        I have just removed it.
1673     8. Three pre-processor statements accidentally did not start in column 1.
1674        Sadly, there are *still* compilers around that complain, even though
1675        standard C has not required this for well over a decade. Sigh.
1677     9. In pcretest, the code for checking callouts passed small integers in the
1678        callout_data field, which is a void * field. However, some picky compilers
1679        complained about the casts involved for this on 64-bit systems. Now
1680        pcretest passes the address of the small integer instead, which should get
1681        rid of the warnings.
1683    10. By default, when in UTF-8 mode, PCRE now checks for valid UTF-8 strings at
1684        both compile and run time, and gives an error if an invalid UTF-8 sequence
1685        is found. There is a option for disabling this check in cases where the
1686        string is known to be correct and/or the maximum performance is wanted.
1688    11. In response to a bug report, I changed one line in Makefile.in from
1690            -Wl,--out-implib,.libs/lib@WIN_PREFIX@pcreposix.dll.a \
1691        to
1692            -Wl,--out-implib,.libs/@WIN_PREFIX@libpcreposix.dll.a \
1694        to look similar to other lines, but I have no way of telling whether this
1695        is the right thing to do, as I do not use Windows. No doubt I'll get told
1696        if it's wrong...
1699    Version 4.3 21-May-03
1700    ---------------------
1702    1. Two instances of @WIN_PREFIX@ omitted from the Windows targets in the
1703       Makefile.
1705    2. Some refactoring to improve the quality of the code:
1707       (i)   The utf8_table... variables are now declared "const".
1709       (ii)  The code for \cx, which used the "case flipping" table to upper case
1710             lower case letters, now just substracts 32. This is ASCII-specific,
1711             but the whole concept of \cx is ASCII-specific, so it seems
1712             reasonable.
1714       (iii) PCRE was using its character types table to recognize decimal and
1715             hexadecimal digits in the pattern. This is silly, because it handles
1716             only 0-9, a-f, and A-F, but the character types table is locale-
1717             specific, which means strange things might happen. A private
1718             table is now used for this - though it costs 256 bytes, a table is
1719             much faster than multiple explicit tests. Of course, the standard
1720             character types table is still used for matching digits in subject
1721             strings against \d.
1723       (iv)  Strictly, the identifier ESC_t is reserved by POSIX (all identifiers
1724             ending in _t are). So I've renamed it as ESC_tee.
1726    3. The first argument for regexec() in the POSIX wrapper should have been
1727       defined as "const".
1729    4. Changed pcretest to use malloc() for its buffers so that they can be
1730       Electric Fenced for debugging.
1732    5. There were several places in the code where, in UTF-8 mode, PCRE would try
1733       to read one or more bytes before the start of the subject string. Often this
1734       had no effect on PCRE's behaviour, but in some circumstances it could
1735       provoke a segmentation fault.
1737    6. A lookbehind at the start of a pattern in UTF-8 mode could also cause PCRE
1738       to try to read one or more bytes before the start of the subject string.
1740    7. A lookbehind in a pattern matched in non-UTF-8 mode on a PCRE compiled with
1741       UTF-8 support could misbehave in various ways if the subject string
1742       contained bytes with the 0x80 bit set and the 0x40 bit unset in a lookbehind
1743       area. (PCRE was not checking for the UTF-8 mode flag, and trying to move
1744       back over UTF-8 characters.)
1747    Version 4.2 14-Apr-03
1748    ---------------------
1750    1. Typo "#if SUPPORT_UTF8" instead of "#ifdef SUPPORT_UTF8" fixed.
1752    2. Changes to the building process, supplied by Ronald Landheer-Cieslak
1753         [ON_WINDOWS]: new variable, "#" on non-Windows platforms
1754         [NOT_ON_WINDOWS]: new variable, "#" on Windows platforms
1755         [WIN_PREFIX]: new variable, "cyg" for Cygwin
1756         * Makefile.in: use autoconf substitution for OBJEXT, EXEEXT, BUILD_OBJEXT
1757           and BUILD_EXEEXT
1758         Note: automatic setting of the BUILD variables is not yet working
1759         set CPPFLAGS and BUILD_CPPFLAGS (but don't use yet) - should be used at
1760           compile-time but not at link-time
1761         [LINK]: use for linking executables only
1762         make different versions for Windows and non-Windows
1763         [LINKLIB]: new variable, copy of UNIX-style LINK, used for linking
1764           libraries
1765         [LINK_FOR_BUILD]: new variable
1766         [OBJEXT]: use throughout
1767         [EXEEXT]: use throughout
1768         <winshared>: new target
1769         <wininstall>: new target
1770         <dftables.o>: use native compiler
1771         <dftables>: use native linker
1772         <install>: handle Windows platform correctly
1773         <clean>: ditto
1774         <check>: ditto
1775         copy DLL to top builddir before testing
1777       As part of these changes, -no-undefined was removed again. This was reported
1778       to give trouble on HP-UX 11.0, so getting rid of it seems like a good idea
1779       in any case.
1781    3. Some tidies to get rid of compiler warnings:
1783       . In the match_data structure, match_limit was an unsigned long int, whereas
1784         match_call_count was an int. I've made them both unsigned long ints.
1786       . In pcretest the fact that a const uschar * doesn't automatically cast to
1787         a void * provoked a warning.
1789       . Turning on some more compiler warnings threw up some "shadow" variables
1790         and a few more missing casts.
1792    4. If PCRE was complied with UTF-8 support, but called without the PCRE_UTF8
1793       option, a class that contained a single character with a value between 128
1794       and 255 (e.g. /[\xFF]/) caused PCRE to crash.
1796    5. If PCRE was compiled with UTF-8 support, but called without the PCRE_UTF8
1797       option, a class that contained several characters, but with at least one
1798       whose value was between 128 and 255 caused PCRE to crash.
1801    Version 4.1 12-Mar-03
1802    ---------------------
1804    1. Compiling with gcc -pedantic found a couple of places where casts were
1805    needed, and a string in dftables.c that was longer than standard compilers are
1806    required to support.
1808    2. Compiling with Sun's compiler found a few more places where the code could
1809    be tidied up in order to avoid warnings.
1811    3. The variables for cross-compiling were called HOST_CC and HOST_CFLAGS; the
1812    first of these names is deprecated in the latest Autoconf in favour of the name
1813    CC_FOR_BUILD, because "host" is typically used to mean the system on which the
1814    compiled code will be run. I can't find a reference for HOST_CFLAGS, but by
1815    analogy I have changed it to CFLAGS_FOR_BUILD.
1817    4. Added -no-undefined to the linking command in the Makefile, because this is
1818    apparently helpful for Windows. To make it work, also added "-L. -lpcre" to the
1819    linking step for the pcreposix library.
1821    5. PCRE was failing to diagnose the case of two named groups with the same
1822    name.
1824    6. A problem with one of PCRE's optimizations was discovered. PCRE remembers a
1825    literal character that is needed in the subject for a match, and scans along to
1826    ensure that it is present before embarking on the full matching process. This
1827    saves time in cases of nested unlimited repeats that are never going to match.
1828    Problem: the scan can take a lot of time if the subject is very long (e.g.
1829    megabytes), thus penalizing straightforward matches. It is now done only if the
1830    amount of subject to be scanned is less than 1000 bytes.
1832    7. A lesser problem with the same optimization is that it was recording the
1833    first character of an anchored pattern as "needed", thus provoking a search
1834    right along the subject, even when the first match of the pattern was going to
1835    fail. The "needed" character is now not set for anchored patterns, unless it
1836    follows something in the pattern that is of non-fixed length. Thus, it still
1837    fulfils its original purpose of finding quick non-matches in cases of nested
1838    unlimited repeats, but isn't used for simple anchored patterns such as /^abc/.
1841    Version 4.0 17-Feb-03
1842    ---------------------
1844    1. If a comment in an extended regex that started immediately after a meta-item
1845    extended to the end of string, PCRE compiled incorrect data. This could lead to
1846    all kinds of weird effects. Example: /#/ was bad; /()#/ was bad; /a#/ was not.
1848    2. Moved to autoconf 2.53 and libtool 1.4.2.
1850    3. Perl 5.8 no longer needs "use utf8" for doing UTF-8 things. Consequently,
1851    the special perltest8 script is no longer needed - all the tests can be run
1852    from a single perltest script.
1854    4. From 5.004, Perl has not included the VT character (0x0b) in the set defined
1855    by \s. It has now been removed in PCRE. This means it isn't recognized as
1856    whitespace in /x regexes too, which is the same as Perl. Note that the POSIX
1857    class [:space:] *does* include VT, thereby creating a mess.
1859    5. Added the class [:blank:] (a GNU extension from Perl 5.8) to match only
1860    space and tab.
1862    6. Perl 5.005 was a long time ago. It's time to amalgamate the tests that use
1863    its new features into the main test script, reducing the number of scripts.
1865    7. Perl 5.8 has changed the meaning of patterns like /a(?i)b/. Earlier versions
1866    were backward compatible, and made the (?i) apply to the whole pattern, as if
1867    /i were given. Now it behaves more logically, and applies the option setting
1868    only to what follows. PCRE has been changed to follow suit. However, if it
1869    finds options settings right at the start of the pattern, it extracts them into
1870    the global options, as before. Thus, they show up in the info data.
1872    8. Added support for the \Q...\E escape sequence. Characters in between are
1873    treated as literals. This is slightly different from Perl in that $ and @ are
1874    also handled as literals inside the quotes. In Perl, they will cause variable
1875    interpolation. Note the following examples:
1877        Pattern            PCRE matches      Perl matches
1879        \Qabc$xyz\E        abc$xyz           abc followed by the contents of $xyz
1880        \Qabc\$xyz\E       abc\$xyz          abc\$xyz
1881        \Qabc\E\$\Qxyz\E   abc$xyz           abc$xyz
1883    For compatibility with Perl, \Q...\E sequences are recognized inside character
1884    classes as well as outside them.
1886    9. Re-organized 3 code statements in pcretest to avoid "overflow in
1887    floating-point constant arithmetic" warnings from a Microsoft compiler. Added a
1888    (size_t) cast to one statement in pcretest and one in pcreposix to avoid
1889    signed/unsigned warnings.
1891    10. SunOS4 doesn't have strtoul(). This was used only for unpicking the -o
1892    option for pcretest, so I've replaced it by a simple function that does just
1893    that job.
1895    11. pcregrep was ending with code 0 instead of 2 for the commands "pcregrep" or
1896    "pcregrep -".
1898    12. Added "possessive quantifiers" ?+, *+, ++, and {,}+ which come from Sun's
1899    Java package. This provides some syntactic sugar for simple cases of what my
1900    documentation calls "once-only subpatterns". A pattern such as x*+ is the same
1901    as (?>x*). In other words, if what is inside (?>...) is just a single repeated
1902    item, you can use this simplified notation. Note that only makes sense with
1903    greedy quantifiers. Consequently, the use of the possessive quantifier forces
1904    greediness, whatever the setting of the PCRE_UNGREEDY option.
1906    13. A change of greediness default within a pattern was not taking effect at
1907    the current level for patterns like /(b+(?U)a+)/. It did apply to parenthesized
1908    subpatterns that followed. Patterns like /b+(?U)a+/ worked because the option
1909    was abstracted outside.
1911    14. PCRE now supports the \G assertion. It is true when the current matching
1912    position is at the start point of the match. This differs from \A when the
1913    starting offset is non-zero. Used with the /g option of pcretest (or similar
1914    code), it works in the same way as it does for Perl's /g option. If all
1915    alternatives of a regex begin with \G, the expression is anchored to the start
1916    match position, and the "anchored" flag is set in the compiled expression.
1918    15. Some bugs concerning the handling of certain option changes within patterns
1919    have been fixed. These applied to options other than (?ims). For example,
1920    "a(?x: b c )d" did not match "XabcdY" but did match "Xa b c dY". It should have
1921    been the other way round. Some of this was related to change 7 above.
1923    16. PCRE now gives errors for /[.x.]/ and /[=x=]/ as unsupported POSIX
1924    features, as Perl does. Previously, PCRE gave the warnings only for /[[.x.]]/
1925    and /[[=x=]]/. PCRE now also gives an error for /[:name:]/ because it supports
1926    POSIX classes only within a class (e.g. /[[:alpha:]]/).
1928    17. Added support for Perl's \C escape. This matches one byte, even in UTF8
1929    mode. Unlike ".", it always matches newline, whatever the setting of
1930    PCRE_DOTALL. However, PCRE does not permit \C to appear in lookbehind
1931    assertions. Perl allows it, but it doesn't (in general) work because it can't
1932    calculate the length of the lookbehind. At least, that's the case for Perl
1933    5.8.0 - I've been told they are going to document that it doesn't work in
1934    future.
1936    18. Added an error diagnosis for escapes that PCRE does not support: these are
1937    \L, \l, \N, \P, \p, \U, \u, and \X.
1939    19. Although correctly diagnosing a missing ']' in a character class, PCRE was
1940    reading past the end of the pattern in cases such as /[abcd/.
1942    20. PCRE was getting more memory than necessary for patterns with classes that
1943    contained both POSIX named classes and other characters, e.g. /[[:space:]abc/.
1945    21. Added some code, conditional on #ifdef VPCOMPAT, to make life easier for
1946    compiling PCRE for use with Virtual Pascal.
1948    22. Small fix to the Makefile to make it work properly if the build is done
1949    outside the source tree.
1951    23. Added a new extension: a condition to go with recursion. If a conditional
1952    subpattern starts with (?(R) the "true" branch is used if recursion has
1953    happened, whereas the "false" branch is used only at the top level.
1955    24. When there was a very long string of literal characters (over 255 bytes
1956    without UTF support, over 250 bytes with UTF support), the computation of how
1957    much memory was required could be incorrect, leading to segfaults or other
1958    strange effects.
1960    25. PCRE was incorrectly assuming anchoring (either to start of subject or to
1961    start of line for a non-DOTALL pattern) when a pattern started with (.*) and
1962    there was a subsequent back reference to those brackets. This meant that, for
1963    example, /(.*)\d+\1/ failed to match "abc123bc". Unfortunately, it isn't
1964    possible to check for precisely this case. All we can do is abandon the
1965    optimization if .* occurs inside capturing brackets when there are any back
1966    references whatsoever. (See below for a better fix that came later.)
1968    26. The handling of the optimization for finding the first character of a
1969    non-anchored pattern, and for finding a character that is required later in the
1970    match were failing in some cases. This didn't break the matching; it just
1971    failed to optimize when it could. The way this is done has been re-implemented.
1973    27. Fixed typo in error message for invalid (?R item (it said "(?p").
1975    28. Added a new feature that provides some of the functionality that Perl
1976    provides with (?{...}). The facility is termed a "callout". The way it is done
1977    in PCRE is for the caller to provide an optional function, by setting
1978    pcre_callout to its entry point. Like pcre_malloc and pcre_free, this is a
1979    global variable. By default it is unset, which disables all calling out. To get
1980    the function called, the regex must include (?C) at appropriate points. This
1981    is, in fact, equivalent to (?C0), and any number <= 255 may be given with (?C).
1982    This provides a means of identifying different callout points. When PCRE
1983    reaches such a point in the regex, if pcre_callout has been set, the external
1984    function is called. It is provided with data in a structure called
1985    pcre_callout_block, which is defined in pcre.h. If the function returns 0,
1986    matching continues; if it returns a non-zero value, the match at the current
1987    point fails. However, backtracking will occur if possible. [This was changed
1988    later and other features added - see item 49 below.]
1990    29. pcretest is upgraded to test the callout functionality. It provides a
1991    callout function that displays information. By default, it shows the start of
1992    the match and the current position in the text. There are some new data escapes
1993    to vary what happens:
1995        \C+         in addition, show current contents of captured substrings
1996        \C-         do not supply a callout function
1997        \C!n        return 1 when callout number n is reached
1998        \C!n!m      return 1 when callout number n is reached for the mth time
2000    30. If pcregrep was called with the -l option and just a single file name, it
2001    output "<stdin>" if a match was found, instead of the file name.
2003    31. Improve the efficiency of the POSIX API to PCRE. If the number of capturing
2004    slots is less than POSIX_MALLOC_THRESHOLD, use a block on the stack to pass to
2005    pcre_exec(). This saves a malloc/free per call. The default value of
2006    POSIX_MALLOC_THRESHOLD is 10; it can be changed by --with-posix-malloc-threshold
2007    when configuring.
2009    32. The default maximum size of a compiled pattern is 64K. There have been a
2010    few cases of people hitting this limit. The code now uses macros to handle the
2011    storing of links as offsets within the compiled pattern. It defaults to 2-byte
2012    links, but this can be changed to 3 or 4 bytes by --with-link-size when
2013    configuring. Tests 2 and 5 work only with 2-byte links because they output
2014    debugging information about compiled patterns.
2016    33. Internal code re-arrangements:
2018    (a) Moved the debugging function for printing out a compiled regex into
2019        its own source file (printint.c) and used #include to pull it into
2020        pcretest.c and, when DEBUG is defined, into pcre.c, instead of having two
2021        separate copies.
2023    (b) Defined the list of op-code names for debugging as a macro in
2024        internal.h so that it is next to the definition of the opcodes.
2026    (c) Defined a table of op-code lengths for simpler skipping along compiled
2027        code. This is again a macro in internal.h so that it is next to the
2028        definition of the opcodes.
2030    34. Added support for recursive calls to individual subpatterns, along the
2031    lines of Robin Houston's patch (but implemented somewhat differently).
2033    35. Further mods to the Makefile to help Win32. Also, added code to pcregrep to
2034    allow it to read and process whole directories in Win32. This code was
2035    contributed by Lionel Fourquaux; it has not been tested by me.
2037    36. Added support for named subpatterns. The Python syntax (?P<name>...) is
2038    used to name a group. Names consist of alphanumerics and underscores, and must
2039    be unique. Back references use the syntax (?P=name) and recursive calls use
2040    (?P>name) which is a PCRE extension to the Python extension. Groups still have
2041    numbers. The function pcre_fullinfo() can be used after compilation to extract
2042    a name/number map. There are three relevant calls:
2044      PCRE_INFO_NAMEENTRYSIZE        yields the size of each entry in the map
2045      PCRE_INFO_NAMECOUNT            yields the number of entries
2046      PCRE_INFO_NAMETABLE            yields a pointer to the map.
2048    The map is a vector of fixed-size entries. The size of each entry depends on
2049    the length of the longest name used. The first two bytes of each entry are the
2050    group number, most significant byte first. There follows the corresponding
2051    name, zero terminated. The names are in alphabetical order.
2053    37. Make the maximum literal string in the compiled code 250 for the non-UTF-8
2054    case instead of 255. Making it the same both with and without UTF-8 support
2055    means that the same test output works with both.
2057    38. There was a case of malloc(0) in the POSIX testing code in pcretest. Avoid
2058    calling malloc() with a zero argument.
2060    39. Change 25 above had to resort to a heavy-handed test for the .* anchoring
2061    optimization. I've improved things by keeping a bitmap of backreferences with
2062    numbers 1-31 so that if .* occurs inside capturing brackets that are not in
2063    fact referenced, the optimization can be applied. It is unlikely that a
2064    relevant occurrence of .* (i.e. one which might indicate anchoring or forcing
2065    the match to follow \n) will appear inside brackets with a number greater than
2066    31, but if it does, any back reference > 31 suppresses the optimization.
2068    40. Added a new compile-time option PCRE_NO_AUTO_CAPTURE. This has the effect
2069    of disabling numbered capturing parentheses. Any opening parenthesis that is
2070    not followed by ? behaves as if it were followed by ?: but named parentheses
2071    can still be used for capturing (and they will acquire numbers in the usual
2072    way).
2074    41. Redesigned the return codes from the match() function into yes/no/error so
2075    that errors can be passed back from deep inside the nested calls. A malloc
2076    failure while inside a recursive subpattern call now causes the
2077    PCRE_ERROR_NOMEMORY return instead of quietly going wrong.
2079    42. It is now possible to set a limit on the number of times the match()
2080    function is called in a call to pcre_exec(). This facility makes it possible to
2081    limit the amount of recursion and backtracking, though not in a directly
2082    obvious way, because the match() function is used in a number of different
2083    circumstances. The count starts from zero for each position in the subject
2084    string (for non-anchored patterns). The default limit is, for compatibility, a
2085    large number, namely 10 000 000. You can change this in two ways:
2087    (a) When configuring PCRE before making, you can use --with-match-limit=n
2088        to set a default value for the compiled library.
2090    (b) For each call to pcre_exec(), you can pass a pcre_extra block in which
2091        a different value is set. See 45 below.
2093    If the limit is exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT.
2095    43. Added a new function pcre_config(int, void *) to enable run-time extraction
2096    of things that can be changed at compile time. The first argument specifies
2097    what is wanted and the second points to where the information is to be placed.
2098    The current list of available information is:
2100      PCRE_CONFIG_UTF8
2102    The output is an integer that is set to one if UTF-8 support is available;
2103    otherwise it is set to zero.
2107    The output is an integer that it set to the value of the code that is used for
2108    newline. It is either LF (10) or CR (13).
2112    The output is an integer that contains the number of bytes used for internal
2113    linkage in compiled expressions. The value is 2, 3, or 4. See item 32 above.
2117    The output is an integer that contains the threshold above which the POSIX
2118    interface uses malloc() for output vectors. See item 31 above.
2122    The output is an unsigned integer that contains the default limit of the number
2123    of match() calls in a pcre_exec() execution. See 42 above.
2125    44. pcretest has been upgraded by the addition of the -C option. This causes it
2126    to extract all the available output from the new pcre_config() function, and to
2127    output it. The program then exits immediately.
2129    45. A need has arisen to pass over additional data with calls to pcre_exec() in
2130    order to support additional features. One way would have been to define
2131    pcre_exec2() (for example) with extra arguments, but this would not have been
2132    extensible, and would also have required all calls to the original function to
2133    be mapped to the new one. Instead, I have chosen to extend the mechanism that
2134    is used for passing in "extra" data from pcre_study().
2136    The pcre_extra structure is now exposed and defined in pcre.h. It currently
2137    contains the following fields:
2139      flags         a bitmap indicating which of the following fields are set
2140      study_data    opaque data from pcre_study()
2141      match_limit   a way of specifying a limit on match() calls for a specific
2142                      call to pcre_exec()
2143      callout_data  data for callouts (see 49 below)
2145    The flag bits are also defined in pcre.h, and are
2151    The pcre_study() function now returns one of these new pcre_extra blocks, with
2152    the actual study data pointed to by the study_data field, and the
2153    PCRE_EXTRA_STUDY_DATA flag set. This can be passed directly to pcre_exec() as
2154    before. That is, this change is entirely upwards-compatible and requires no
2155    change to existing code.
2157    If you want to pass in additional data to pcre_exec(), you can either place it
2158    in a pcre_extra block provided by pcre_study(), or create your own pcre_extra
2159    block.
2161    46. pcretest has been extended to test the PCRE_EXTRA_MATCH_LIMIT feature. If a
2162    data string contains the escape sequence \M, pcretest calls pcre_exec() several
2163    times with different match limits, until it finds the minimum value needed for
2164    pcre_exec() to complete. The value is then output. This can be instructive; for
2165    most simple matches the number is quite small, but for pathological cases it
2166    gets very large very quickly.
2168    47. There's a new option for pcre_fullinfo() called PCRE_INFO_STUDYSIZE. It
2169    returns the size of the data block pointed to by the study_data field in a
2170    pcre_extra block, that is, the value that was passed as the argument to
2171    pcre_malloc() when PCRE was getting memory in which to place the information
2172    created by pcre_study(). The fourth argument should point to a size_t variable.
2173    pcretest has been extended so that this information is shown after a successful
2174    pcre_study() call when information about the compiled regex is being displayed.
2176    48. Cosmetic change to Makefile: there's no need to have / after $(DESTDIR)
2177    because what follows is always an absolute path. (Later: it turns out that this
2178    is more than cosmetic for MinGW, because it doesn't like empty path
2179    components.)
2181    49. Some changes have been made to the callout feature (see 28 above):
2183    (i)  A callout function now has three choices for what it returns:
2185           0  =>  success, carry on matching
2186         > 0  =>  failure at this point, but backtrack if possible
2187         < 0  =>  serious error, return this value from pcre_exec()
2189         Negative values should normally be chosen from the set of PCRE_ERROR_xxx
2190         values. In particular, returning PCRE_ERROR_NOMATCH forces a standard
2191         "match failed" error. The error number PCRE_ERROR_CALLOUT is reserved for
2192         use by callout functions. It will never be used by PCRE itself.
2194    (ii) The pcre_extra structure (see 45 above) has a void * field called
2195         callout_data, with corresponding flag bit PCRE_EXTRA_CALLOUT_DATA. The
2196         pcre_callout_block structure has a field of the same name. The contents of
2197         the field passed in the pcre_extra structure are passed to the callout
2198         function in the corresponding field in the callout block. This makes it
2199         easier to use the same callout-containing regex from multiple threads. For
2200         testing, the pcretest program has a new data escape
2202           \C*n        pass the number n (may be negative) as callout_data
2204         If the callout function in pcretest receives a non-zero value as
2205         callout_data, it returns that value.
2207    50. Makefile wasn't handling CFLAGS properly when compiling dftables. Also,
2208    there were some redundant $(CFLAGS) in commands that are now specified as
2209    $(LINK), which already includes $(CFLAGS).
2211    51. Extensions to UTF-8 support are listed below. These all apply when (a) PCRE
2212    has been compiled with UTF-8 support *and* pcre_compile() has been compiled
2213    with the PCRE_UTF8 flag. Patterns that are compiled without that flag assume
2214    one-byte characters throughout. Note that case-insensitive matching applies
2215    only to characters whose values are less than 256. PCRE doesn't support the
2216    notion of cases for higher-valued characters.
2218    (i)   A character class whose characters are all within 0-255 is handled as
2219          a bit map, and the map is inverted for negative classes. Previously, a
2220          character > 255 always failed to match such a class; however it should
2221          match if the class was a negative one (e.g. [^ab]). This has been fixed.
2223    (ii)  A negated character class with a single character < 255 is coded as
2224          "not this character" (OP_NOT). This wasn't working properly when the test
2225          character was multibyte, either singly or repeated.
2227    (iii) Repeats of multibyte characters are now handled correctly in UTF-8
2228          mode, for example: \x{100}{2,3}.
2230    (iv)  The character escapes \b, \B, \d, \D, \s, \S, \w, and \W (either
2231          singly or repeated) now correctly test multibyte characters. However,
2232          PCRE doesn't recognize any characters with values greater than 255 as
2233          digits, spaces, or word characters. Such characters always match \D, \S,
2234          and \W, and never match \d, \s, or \w.
2236    (v)   Classes may now contain characters and character ranges with values
2237          greater than 255. For example: [ab\x{100}-\x{400}].
2239    (vi)  pcregrep now has a --utf-8 option (synonym -u) which makes it call
2240          PCRE in UTF-8 mode.
2242    52. The info request value PCRE_INFO_FIRSTCHAR has been renamed
2243    PCRE_INFO_FIRSTBYTE because it is a byte value. However, the old name is
2244    retained for backwards compatibility. (Note that LASTLITERAL is also a byte
2245    value.)
2247    53. The single man page has become too large. I have therefore split it up into
2248    a number of separate man pages. These also give rise to individual HTML pages;
2249    these are now put in a separate directory, and there is an index.html page that
2250    lists them all. Some hyperlinking between the pages has been installed.
2252    54. Added convenience functions for handling named capturing parentheses.
2254    55. Unknown escapes inside character classes (e.g. [\M]) and escapes that
2255    aren't interpreted therein (e.g. [\C]) are literals in Perl. This is now also
2256    true in PCRE, except when the PCRE_EXTENDED option is set, in which case they
2257    are faulted.
2259    56. Introduced HOST_CC and HOST_CFLAGS which can be set in the environment when
2260    calling configure. These values are used when compiling the dftables.c program
2261    which is run to generate the source of the default character tables. They
2262    default to the values of CC and CFLAGS. If you are cross-compiling PCRE,
2263    you will need to set these values.
2265    57. Updated the building process for Windows DLL, as provided by Fred Cox.
2268    Version 3.9 02-Jan-02
2269    ---------------------
2271    1. A bit of extraneous text had somehow crept into the pcregrep documentation.
2273    2. If --disable-static was given, the building process failed when trying to
2274    build pcretest and pcregrep. (For some reason it was using libtool to compile
2275    them, which is not right, as they aren't part of the library.)
2278    Version 3.8 18-Dec-01
2279    ---------------------
2281    1. The experimental UTF-8 code was completely screwed up. It was packing the
2282    bytes in the wrong order. How dumb can you get?
2285    Version 3.7 29-Oct-01
2286    ---------------------
2288    1. In updating pcretest to check change 1 of version 3.6, I screwed up.
2289    This caused pcretest, when used on the test data, to segfault. Unfortunately,
2290    this didn't happen under Solaris 8, where I normally test things.
2292    2. The Makefile had to be changed to make it work on BSD systems, where 'make'
2293    doesn't seem to recognize that ./xxx and xxx are the same file. (This entry
2294    isn't in ChangeLog distributed with 3.7 because I forgot when I hastily made
2295    this fix an hour or so after the initial 3.7 release.)
2298    Version 3.6 23-Oct-01
2299    ---------------------
2301    1. Crashed with /(sens|respons)e and \1ibility/ and "sense and sensibility" if
2302    offsets passed as NULL with zero offset count.
2304    2. The config.guess and config.sub files had not been updated when I moved to
2305    the latest autoconf.
2308    Version 3.5 15-Aug-01
2309    ---------------------
2311    1. Added some missing #if !defined NOPOSIX conditionals in pcretest.c that
2312    had been forgotten.
2314    2. By using declared but undefined structures, we can avoid using "void"
2315    definitions in pcre.h while keeping the internal definitions of the structures
2316    private.
2318    3. The distribution is now built using autoconf 2.50 and libtool 1.4. From a
2319    user point of view, this means that both static and shared libraries are built
2320    by default, but this can be individually controlled. More of the work of
2321    handling this static/shared cases is now inside libtool instead of PCRE's make
2322    file.
2324    4. The pcretest utility is now installed along with pcregrep because it is
2325    useful for users (to test regexs) and by doing this, it automatically gets
2326    relinked by libtool. The documentation has been turned into a man page, so
2327    there are now .1, .txt, and .html versions in /doc.
2329    5. Upgrades to pcregrep:
2330       (i)   Added long-form option names like gnu grep.
2331       (ii)  Added --help to list all options with an explanatory phrase.
2332       (iii) Added -r, --recursive to recurse into sub-directories.
2333       (iv)  Added -f, --file to read patterns from a file.
2335    6. pcre_exec() was referring to its "code" argument before testing that
2336    argument for NULL (and giving an error if it was NULL).
2338    7. Upgraded Makefile.in to allow for compiling in a different directory from
2339    the source directory.
2341    8. Tiny buglet in pcretest: when pcre_fullinfo() was called to retrieve the
2342    options bits, the pointer it was passed was to an int instead of to an unsigned
2343    long int. This mattered only on 64-bit systems.
2345    9. Fixed typo (3.4/1) in pcre.h again. Sigh. I had changed pcre.h (which is
2346    generated) instead of pcre.in, which it its source. Also made the same change
2347    in several of the .c files.
2349    10. A new release of gcc defines printf() as a macro, which broke pcretest
2350    because it had an ifdef in the middle of a string argument for printf(). Fixed
2351    by using separate calls to printf().
2353    11. Added --enable-newline-is-cr and --enable-newline-is-lf to the configure
2354    script, to force use of CR or LF instead of \n in the source. On non-Unix
2355    systems, the value can be set in config.h.
2357    12. The limit of 200 on non-capturing parentheses is a _nesting_ limit, not an
2358    absolute limit. Changed the text of the error message to make this clear, and
2359    likewise updated the man page.
2361    13. The limit of 99 on the number of capturing subpatterns has been removed.
2362    The new limit is 65535, which I hope will not be a "real" limit.
2365    Version 3.4 22-Aug-00
2366    ---------------------
2368    1. Fixed typo in pcre.h: unsigned const char * changed to const unsigned char *.
2370    2. Diagnose condition (?(0) as an error instead of crashing on matching.
2373    Version 3.3 01-Aug-00
2374    ---------------------
2376    1. If an octal character was given, but the value was greater than \377, it
2377    was not getting masked to the least significant bits, as documented. This could
2378    lead to crashes in some systems.
2380    2. Perl 5.6 (if not earlier versions) accepts classes like [a-\d] and treats
2381    the hyphen as a literal. PCRE used to give an error; it now behaves like Perl.
2383    3. Added the functions pcre_free_substring() and pcre_free_substring_list().
2384    These just pass their arguments on to (pcre_free)(), but they are provided
2385    because some uses of PCRE bind it to non-C systems that can call its functions,
2386    but cannot call free() or pcre_free() directly.
2388    4. Add "make test" as a synonym for "make check". Corrected some comments in
2389    the Makefile.
2391    5. Add $(DESTDIR)/ in front of all the paths in the "install" target in the
2392    Makefile.
2394    6. Changed the name of pgrep to pcregrep, because Solaris has introduced a
2395    command called pgrep for grepping around the active processes.
2397    7. Added the beginnings of support for UTF-8 character strings.
2399    8. Arranged for the Makefile to pass over the settings of CC, CFLAGS, and
2400    RANLIB to ./ltconfig so that they are used by libtool. I think these are all
2401    the relevant ones. (AR is not passed because ./ltconfig does its own figuring
2402    out for the ar command.)
2405    Version 3.2 12-May-00
2406    ---------------------
2408    This is purely a bug fixing release.
2410    1. If the pattern /((Z)+|A)*/ was matched agained ZABCDEFG it matched Z instead
2411    of ZA. This was just one example of several cases that could provoke this bug,
2412    which was introduced by change 9 of version 2.00. The code for breaking
2413    infinite loops after an iteration that matches an empty string was't working
2414    correctly.
2416    2. The pcretest program was not imitating Perl correctly for the pattern /a*/g
2417    when matched against abbab (for example). After matching an empty string, it
2418    wasn't forcing anchoring when setting PCRE_NOTEMPTY for the next attempt; this
2419    caused it to match further down the string than it should.
2421    3. The code contained an inclusion of sys/types.h. It isn't clear why this
2422    was there because it doesn't seem to be needed, and it causes trouble on some
2423    systems, as it is not a Standard C header. It has been removed.
2425    4. Made 4 silly changes to the source to avoid stupid compiler warnings that
2426    were reported on the Macintosh. The changes were from
2428      while ((c = *(++ptr)) != 0 && c != '\n');
2429    to
2430      while ((c = *(++ptr)) != 0 && c != '\n') ;
2432    Totally extraordinary, but if that's what it takes...
2434    5. PCRE is being used in one environment where neither memmove() nor bcopy() is
2435    available. Added HAVE_BCOPY and an autoconf test for it; if neither
2436    HAVE_MEMMOVE nor HAVE_BCOPY is set, use a built-in emulation function which
2437    assumes the way PCRE uses memmove() (always moving upwards).
2439    6. PCRE is being used in one environment where strchr() is not available. There
2440    was only one use in pcre.c, and writing it out to avoid strchr() probably gives
2441    faster code anyway.
2444    Version 3.1 09-Feb-00
2445    ---------------------
2447    The only change in this release is the fixing of some bugs in Makefile.in for
2448    the "install" target:
2450    (1) It was failing to install pcreposix.h.
2452    (2) It was overwriting the pcre.3 man page with the pcreposix.3 man page.
2455    Version 3.0 01-Feb-00
2456    ---------------------
2458    1. Add support for the /+ modifier to perltest (to output $` like it does in
2459    pcretest).
2461    2. Add support for the /g modifier to perltest.
2463    3. Fix pcretest so that it behaves even more like Perl for /g when the pattern
2464    matches null strings.
2466    4. Fix perltest so that it doesn't do unwanted things when fed an empty
2467    pattern. Perl treats empty patterns specially - it reuses the most recent
2468    pattern, which is not what we want. Replace // by /(?#)/ in order to avoid this
2469    effect.
2471    5. The POSIX interface was broken in that it was just handing over the POSIX
2472    captured string vector to pcre_exec(), but (since release 2.00) PCRE has
2473    required a bigger vector, with some working space on the end. This means that
2474    the POSIX wrapper now has to get and free some memory, and copy the results.
2476    6. Added some simple autoconf support, placing the test data and the
2477    documentation in separate directories, re-organizing some of the
2478    information files, and making it build pcre-config (a GNU standard). Also added
2479    libtool support for building PCRE as a shared library, which is now the
2480    default.
2482    7. Got rid of the leading zero in the definition of PCRE_MINOR because 08 and
2483    09 are not valid octal constants. Single digits will be used for minor values
2484    less than 10.
2486    8. Defined REG_EXTENDED and REG_NOSUB as zero in the POSIX header, so that
2487    existing programs that set these in the POSIX interface can use PCRE without
2488    modification.
2490    9. Added a new function, pcre_fullinfo() with an extensible interface. It can
2491    return all that pcre_info() returns, plus additional data. The pcre_info()
2492    function is retained for compatibility, but is considered to be obsolete.
2494    10. Added experimental recursion feature (?R) to handle one common case that
2495    Perl 5.6 will be able to do with (?p{...}).
2497    11. Added support for POSIX character classes like [:alpha:], which Perl is
2498    adopting.
2501    Version 2.08 31-Aug-99
2502    ----------------------
2504    1. When startoffset was not zero and the pattern began with ".*", PCRE was not
2505    trying to match at the startoffset position, but instead was moving forward to
2506    the next newline as if a previous match had failed.
2508    2. pcretest was not making use of PCRE_NOTEMPTY when repeating for /g and /G,
2509    and could get into a loop if a null string was matched other than at the start
2510    of the subject.
2512    3. Added definitions of PCRE_MAJOR and PCRE_MINOR to pcre.h so the version can
2513    be distinguished at compile time, and for completeness also added PCRE_DATE.
2515    5. Added Paul Sokolovsky's minor changes to make it easy to compile a Win32 DLL
2516    in GnuWin32 environments.
2519    Version 2.07 29-Jul-99
2520    ----------------------
2522    1. The documentation is now supplied in plain text form and HTML as well as in
2523    the form of man page sources.
2525    2. C++ compilers don't like assigning (void *) values to other pointer types.
2526    In particular this affects malloc(). Although there is no problem in Standard
2527    C, I've put in casts to keep C++ compilers happy.
2529    3. Typo on pcretest.c; a cast of (unsigned char *) in the POSIX regexec() call
2530    should be (const char *).
2532    4. If NOPOSIX is defined, pcretest.c compiles without POSIX support. This may
2533    be useful for non-Unix systems who don't want to bother with the POSIX stuff.
2534    However, I haven't made this a standard facility. The documentation doesn't
2535    mention it, and the Makefile doesn't support it.
2537    5. The Makefile now contains an "install" target, with editable destinations at
2538    the top of the file. The pcretest program is not installed.
2540    6. pgrep -V now gives the PCRE version number and date.
2542    7. Fixed bug: a zero repetition after a literal string (e.g. /abcde{0}/) was
2543    causing the entire string to be ignored, instead of just the last character.
2545    8. If a pattern like /"([^\\"]+|\\.)*"/ is applied in the normal way to a
2546    non-matching string, it can take a very, very long time, even for strings of
2547    quite modest length, because of the nested recursion. PCRE now does better in
2548    some of these cases. It does this by remembering the last required literal
2549    character in the pattern, and pre-searching the subject to ensure it is present
2550    before running the real match. In other words, it applies a heuristic to detect
2551    some types of certain failure quickly, and in the above example, if presented
2552    with a string that has no trailing " it gives "no match" very quickly.
2554    9. A new runtime option PCRE_NOTEMPTY causes null string matches to be ignored;
2555    other alternatives are tried instead.
2558    Version 2.06 09-Jun-99
2559    ----------------------
2561    1. Change pcretest's output for amount of store used to show just the code
2562    space, because the remainder (the data block) varies in size between 32-bit and
2563    64-bit systems.
2565    2. Added an extra argument to pcre_exec() to supply an offset in the subject to
2566    start matching at. This allows lookbehinds to work when searching for multiple
2567    occurrences in a string.
2569    3. Added additional options to pcretest for testing multiple occurrences:
2571       /+   outputs the rest of the string that follows a match
2572       /g   loops for multiple occurrences, using the new startoffset argument
2573       /G   loops for multiple occurrences by passing an incremented pointer
2575    4. PCRE wasn't doing the "first character" optimization for patterns starting
2576    with \b or \B, though it was doing it for other lookbehind assertions. That is,
2577    it wasn't noticing that a match for a pattern such as /\bxyz/ has to start with
2578    the letter 'x'. On long subject strings, this gives a significant speed-up.
2581    Version 2.05 21-Apr-99
2582    ----------------------
2584    1. Changed the type of magic_number from int to long int so that it works
2585    properly on 16-bit systems.
2587    2. Fixed a bug which caused patterns starting with .* not to work correctly
2588    when the subject string contained newline characters. PCRE was assuming
2589    anchoring for such patterns in all cases, which is not correct because .* will
2590    not pass a newline unless PCRE_DOTALL is set. It now assumes anchoring only if
2591    DOTALL is set at top level; otherwise it knows that patterns starting with .*
2592    must be retried after every newline in the subject.
2595    Version 2.04 18-Feb-99
2596    ----------------------
2598    1. For parenthesized subpatterns with repeats whose minimum was zero, the
2599    computation of the store needed to hold the pattern was incorrect (too large).
2600    If such patterns were nested a few deep, this could multiply and become a real
2601    problem.
2603    2. Added /M option to pcretest to show the memory requirement of a specific
2604    pattern. Made -m a synonym of -s (which does this globally) for compatibility.
2606    3. Subpatterns of the form (regex){n,m} (i.e. limited maximum) were being
2607    compiled in such a way that the backtracking after subsequent failure was
2608    pessimal. Something like (a){0,3} was compiled as (a)?(a)?(a)? instead of
2609    ((a)((a)(a)?)?)? with disastrous performance if the maximum was of any size.
2612    Version 2.03 02-Feb-99
2613    ----------------------
2615    1. Fixed typo and small mistake in man page.
2617    2. Added 4th condition (GPL supersedes if conflict) and created separate
2618    LICENCE file containing the conditions.
2620    3. Updated pcretest so that patterns such as /abc\/def/ work like they do in
2621    Perl, that is the internal \ allows the delimiter to be included in the
2622    pattern. Locked out the use of \ as a delimiter. If \ immediately follows
2623    the final delimiter, add \ to the end of the pattern (to test the error).
2625    4. Added the convenience functions for extracting substrings after a successful
2626    match. Updated pcretest to make it able to test these functions.
2629    Version 2.02 14-Jan-99
2630    ----------------------
2632    1. Initialized the working variables associated with each extraction so that
2633    their saving and restoring doesn't refer to uninitialized store.
2635    2. Put dummy code into study.c in order to trick the optimizer of the IBM C
2636    compiler for OS/2 into generating correct code. Apparently IBM isn't going to
2637    fix the problem.
2639    3. Pcretest: the timing code wasn't using LOOPREPEAT for timing execution
2640    calls, and wasn't printing the correct value for compiling calls. Increased the
2641    default value of LOOPREPEAT, and the number of significant figures in the
2642    times.
2644    4. Changed "/bin/rm" in the Makefile to "-rm" so it works on Windows NT.
2646    5. Renamed "deftables" as "dftables" to get it down to 8 characters, to avoid
2647    a building problem on Windows NT with a FAT file system.
2650    Version 2.01 21-Oct-98
2651    ----------------------
2653    1. Changed the API for pcre_compile() to allow for the provision of a pointer
2654    to character tables built by pcre_maketables() in the current locale. If NULL
2655    is passed, the default tables are used.
2658    Version 2.00 24-Sep-98
2659    ----------------------
2661    1. Since the (>?) facility is in Perl 5.005, don't require PCRE_EXTRA to enable
2662    it any more.
2664    2. Allow quantification of (?>) groups, and make it work correctly.
2666    3. The first character computation wasn't working for (?>) groups.
2668    4. Correct the implementation of \Z (it is permitted to match on the \n at the
2669    end of the subject) and add 5.005's \z, which really does match only at the
2670    very end of the subject.
2672    5. Remove the \X "cut" facility; Perl doesn't have it, and (?> is neater.
2674    6. Remove the ability to specify CASELESS, MULTILINE, DOTALL, and
2675    DOLLAR_END_ONLY at runtime, to make it possible to implement the Perl 5.005
2676    localized options. All options to pcre_study() were also removed.
2678    7. Add other new features from 5.005:
2680       $(?<=           positive lookbehind
2681       $(?<!           negative lookbehind
2682       (?imsx-imsx)    added the unsetting capability
2683                       such a setting is global if at outer level; local otherwise
2684       (?imsx-imsx:)   non-capturing groups with option setting
2685       (?(cond)re|re)  conditional pattern matching
2687       A backreference to itself in a repeated group matches the previous
2688       captured string.
2690    8. General tidying up of studying (both automatic and via "study")
2691    consequential on the addition of new assertions.
2693    9. As in 5.005, unlimited repeated groups that could match an empty substring
2694    are no longer faulted at compile time. Instead, the loop is forcibly broken at
2695    runtime if any iteration does actually match an empty substring.
2697    10. Include the RunTest script in the distribution.
2699    11. Added tests from the Perl 5.005_02 distribution. This showed up a few
2700    discrepancies, some of which were old and were also with respect to 5.004. They
2701    have now been fixed.
2704    Version 1.09 28-Apr-98
2705    ----------------------
2707    1. A negated single character class followed by a quantifier with a minimum
2708    value of one (e.g.  [^x]{1,6}  ) was not compiled correctly. This could lead to
2709    program crashes, or just wrong answers. This did not apply to negated classes
2710    containing more than one character, or to minima other than one.
2713    Version 1.08 27-Mar-98
2714    ----------------------
2716    1. Add PCRE_UNGREEDY to invert the greediness of quantifiers.
2718    2. Add (?U) and (?X) to set PCRE_UNGREEDY and PCRE_EXTRA respectively. The
2719    latter must appear before anything that relies on it in the pattern.
2722    Version 1.07 16-Feb-98
2723    ----------------------
2725    1. A pattern such as /((a)*)*/ was not being diagnosed as in error (unlimited
2726    repeat of a potentially empty string).
2729    Version 1.06 23-Jan-98
2730    ----------------------
2732    1. Added Markus Oberhumer's little patches for C++.
2734    2. Literal strings longer than 255 characters were broken.
2737    Version 1.05 23-Dec-97
2738    ----------------------
2740    1. Negated character classes containing more than one character were failing if
2741    PCRE_CASELESS was set at run time.
2744    Version 1.04 19-Dec-97
2745    ----------------------
2747    1. Corrected the man page, where some "const" qualifiers had been omitted.
2749    2. Made debugging output print "{0,xxx}" instead of just "{,xxx}" to agree with
2750    input syntax.
2752    3. Fixed memory leak which occurred when a regex with back references was
2753    matched with an offsets vector that wasn't big enough. The temporary memory
2754    that is used in this case wasn't being freed if the match failed.
2756    4. Tidied pcretest to ensure it frees memory that it gets.
2758    5. Temporary memory was being obtained in the case where the passed offsets
2759    vector was exactly big enough.
2761    6. Corrected definition of offsetof() from change 5 below.
2763    7. I had screwed up change 6 below and broken the rules for the use of
2764    setjmp(). Now fixed.
2767    Version 1.03 18-Dec-97
2768    ----------------------
2770    1. A erroneous regex with a missing opening parenthesis was correctly
2771    diagnosed, but PCRE attempted to access brastack[-1], which could cause crashes
2772    on some systems.
2774    2. Replaced offsetof(real_pcre, code) by offsetof(real_pcre, code[0]) because
2775    it was reported that one broken compiler failed on the former because "code" is
2776    also an independent variable.
2778    3. The erroneous regex a[]b caused an array overrun reference.
2780    4. A regex ending with a one-character negative class (e.g. /[^k]$/) did not
2781    fail on data ending with that character. (It was going on too far, and checking
2782    the next character, typically a binary zero.) This was specific to the
2783    optimized code for single-character negative classes.
2785    5. Added a contributed patch from the TIN world which does the following:
2787      + Add an undef for memmove, in case the the system defines a macro for it.
2789      + Add a definition of offsetof(), in case there isn't one. (I don't know
2790        the reason behind this - offsetof() is part of the ANSI standard - but
2791        it does no harm).
2793      + Reduce the ifdef's in pcre.c using macro DPRINTF, thereby eliminating
2794        most of the places where whitespace preceded '#'. I have given up and
2795        allowed the remaining 2 cases to be at the margin.
2797      + Rename some variables in pcre to eliminate shadowing. This seems very
2798        pedantic, but does no harm, of course.
2800    6. Moved the call to setjmp() into its own function, to get rid of warnings
2801    from gcc -Wall, and avoided calling it at all unless PCRE_EXTRA is used.
2803    7. Constructs such as \d{8,} were compiling into the equivalent of
2804    \d{8}\d{0,65527} instead of \d{8}\d* which didn't make much difference to the
2805    outcome, but in this particular case used more store than had been allocated,
2806    which caused the bug to be discovered because it threw up an internal error.
2808    8. The debugging code in both pcre and pcretest for outputting the compiled
2809    form of a regex was going wrong in the case of back references followed by
2810    curly-bracketed repeats.
2813  Version 1.02 12-Dec-97  Version 1.02 12-Dec-97
2814  ----------------------  ----------------------

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