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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
4    Version 7.5 12-Nov-07
5    ---------------------
7    1.  Applied a patch from Craig: "This patch makes it possible to 'ignore'
8        values in parens when parsing an RE using the C++ wrapper."
10    2.  Negative specials like \S did not work in character classes in UTF-8 mode.
11        Characters greater than 255 were excluded from the class instead of being
12        included.
14    3.  The same bug as (2) above applied to negated POSIX classes such as
15        [:^space:].
17    4.  PCRECPP_STATIC was referenced in pcrecpp_internal.h, but nowhere was it
18        defined or documented. It seems to have been a typo for PCRE_STATIC, so
19        I have changed it.
21    5.  The construct (?&) was not diagnosed as a syntax error (it referenced the
22        first named subpattern) and a construct such as (?&a) would reference the
23        first named subpattern whose name started with "a" (in other words, the
24        length check was missing). Both these problems are fixed. "Subpattern name
25        expected" is now given for (?&) (a zero-length name), and this patch also
26        makes it give the same error for \k'' (previously it complained that that
27        was a reference to a non-existent subpattern).
29    6.  The erroneous patterns (?+-a) and (?-+a) give different error messages;
30        this is right because (?- can be followed by option settings as well as by
31        digits. I have, however, made the messages clearer.
33    7.  Patterns such as (?(1)a|b) (a pattern that contains fewer subpatterns
34        than the number used in the conditional) now cause a compile-time error.
35        This is actually not compatible with Perl, which accepts such patterns, but
36        treats the conditional as always being FALSE (as PCRE used to), but it
37        seems to me that giving a diagnostic is better.
39    8.  Change "alphameric" to the more common word "alphanumeric" in comments
40        and messages.
42    9.  Fix two occurrences of "backslash" in comments that should have been
43        "backspace".
45    10. Remove two redundant lines of code that can never be obeyed (their function
46        was moved elsewhere).
48    11. The program that makes PCRE's Unicode character property table had a bug
49        which caused it to generate incorrect table entries for sequences of
50        characters that have the same character type, but are in different scripts.
51        It amalgamated them into a single range, with the script of the first of
52        them. In other words, some characters were in the wrong script. There were
53        thirteen such cases, affecting characters in the following ranges:
55          U+002b0 - U+002c1
56          U+0060c - U+0060d
57          U+0061e - U+00612
58          U+0064b - U+0065e
59          U+0074d - U+0076d
60          U+01800 - U+01805
61          U+01d00 - U+01d77
62          U+01d9b - U+01dbf
63          U+0200b - U+0200f
64          U+030fc - U+030fe
65          U+03260 - U+0327f
66          U+0fb46 - U+0fbb1
67          U+10450 - U+1049d
69    12. The -o option (show only the matching part of a line) for pcregrep was not
70        compatible with GNU grep in that, if there was more than one match in a
71        line, it showed only the first of them. It now behaves in the same way as
72        GNU grep.
74    13. If the -o and -v options were combined for pcregrep, it printed a blank
75        line for every non-matching line. GNU grep prints nothing, and pcregrep now
76        does the same. The return code can be used to tell if there were any
77        non-matching lines.
79    14. The pattern (?=something)(?R) was not being diagnosed as a potentially
80        infinitely looping recursion. The bug was that positive lookaheads were not
81        being skipped when checking for a possible empty match (negative lookaheads
82        and both kinds of lookbehind were skipped).
84    15. Fixed two typos in the Windows-only code in pcregrep.c, and moved the
85        inclusion of <windows.h> to before rather than after the definition of
86        INVALID_FILE_ATTRIBUTES (patch from David Byron).
88    16. Specifying a possessive quantifier with a specific limit for a Unicode
89        character property caused pcre_compile() to compile bad code, which led at
90        runtime to PCRE_ERROR_INTERNAL (-14). Examples of patterns that caused this
91        are: /\p{Zl}{2,3}+/8 and /\p{Cc}{2}+/8. It was the possessive "+" that
92        caused the error; without that there was no problem.
95    Version 7.4 21-Sep-07
96    ---------------------
98    1.  Change 7.3/28 was implemented for classes by looking at the bitmap. This
99        means that a class such as [\s] counted as "explicit reference to CR or
100        LF". That isn't really right - the whole point of the change was to try to
101        help when there was an actual mention of one of the two characters. So now
102        the change happens only if \r or \n (or a literal CR or LF) character is
103        encountered.
105    2.  The 32-bit options word was also used for 6 internal flags, but the numbers
106        of both had grown to the point where there were only 3 bits left.
107        Fortunately, there was spare space in the data structure, and so I have
108        moved the internal flags into a new 16-bit field to free up more option
109        bits.
111    3.  The appearance of (?J) at the start of a pattern set the DUPNAMES option,
112        but did not set the internal JCHANGED flag - either of these is enough to
113        control the way the "get" function works - but the PCRE_INFO_JCHANGED
114        facility is supposed to tell if (?J) was ever used, so now (?J) at the
115        start sets both bits.
117    4.  Added options (at build time, compile time, exec time) to change \R from
118        matching any Unicode line ending sequence to just matching CR, LF, or CRLF.
120    5.  doc/pcresyntax.html was missing from the distribution.
122    6.  Put back the definition of PCRE_ERROR_NULLWSLIMIT, for backward
123        compatibility, even though it is no longer used.
125    7.  Added macro for snprintf to pcrecpp_unittest.cc and also for strtoll and
126        strtoull to pcrecpp.cc to select the available functions in WIN32 when the
127        windows.h file is present (where different names are used). [This was
128        reversed later after testing - see 16 below.]
130    8.  Changed all #include <config.h> to #include "config.h". There were also
131        some further <pcre.h> cases that I changed to "pcre.h".
133    9.  When pcregrep was used with the --colour option, it missed the line ending
134        sequence off the lines that it output.
136    10. It was pointed out to me that arrays of string pointers cause lots of
137        relocations when a shared library is dynamically loaded. A technique of
138        using a single long string with a table of offsets can drastically reduce
139        these. I have refactored PCRE in four places to do this. The result is
140        dramatic:
142          Originally:                          290
143          After changing UCP table:            187
144          After changing error message table:   43
145          After changing table of "verbs"       36
146          After changing table of Posix names   22
148        Thanks to the folks working on Gregex for glib for this insight.
150    11. --disable-stack-for-recursion caused compiling to fail unless -enable-
151        unicode-properties was also set.
153    12. Updated the tests so that they work when \R is defaulted to ANYCRLF.
155    13. Added checks for ANY and ANYCRLF to pcrecpp.cc where it previously
156        checked only for CRLF.
158    14. Added casts to pcretest.c to avoid compiler warnings.
160    15. Added Craig's patch to various pcrecpp modules to avoid compiler warnings.
162    16. Added Craig's patch to remove the WINDOWS_H tests, that were not working,
163        and instead check for _strtoi64 explicitly, and avoid the use of snprintf()
164        entirely. This removes changes made in 7 above.
166    17. The CMake files have been updated, and there is now more information about
167        building with CMake in the NON-UNIX-USE document.
170    Version 7.3 28-Aug-07
171    ---------------------
173     1. In the rejigging of the build system that eventually resulted in 7.1, the
174        line "#include <pcre.h>" was included in pcre_internal.h. The use of angle
175        brackets there is not right, since it causes compilers to look for an
176        installed pcre.h, not the version that is in the source that is being
177        compiled (which of course may be different). I have changed it back to:
179          #include "pcre.h"
181        I have a vague recollection that the change was concerned with compiling in
182        different directories, but in the new build system, that is taken care of
183        by the VPATH setting the Makefile.
185     2. The pattern .*$ when run in not-DOTALL UTF-8 mode with newline=any failed
186        when the subject happened to end in the byte 0x85 (e.g. if the last
187        character was \x{1ec5}). *Character* 0x85 is one of the "any" newline
188        characters but of course it shouldn't be taken as a newline when it is part
189        of another character. The bug was that, for an unlimited repeat of . in
190        not-DOTALL UTF-8 mode, PCRE was advancing by bytes rather than by
191        characters when looking for a newline.
193     3. A small performance improvement in the DOTALL UTF-8 mode .* case.
195     4. Debugging: adjusted the names of opcodes for different kinds of parentheses
196        in debug output.
198     5. Arrange to use "%I64d" instead of "%lld" and "%I64u" instead of "%llu" for
199        long printing in the pcrecpp unittest when running under MinGW.
201     6. ESC_K was left out of the EBCDIC table.
203     7. Change 7.0/38 introduced a new limit on the number of nested non-capturing
204        parentheses; I made it 1000, which seemed large enough. Unfortunately, the
205        limit also applies to "virtual nesting" when a pattern is recursive, and in
206        this case 1000 isn't so big. I have been able to remove this limit at the
207        expense of backing off one optimization in certain circumstances. Normally,
208        when pcre_exec() would call its internal match() function recursively and
209        immediately return the result unconditionally, it uses a "tail recursion"
210        feature to save stack. However, when a subpattern that can match an empty
211        string has an unlimited repetition quantifier, it no longer makes this
212        optimization. That gives it a stack frame in which to save the data for
213        checking that an empty string has been matched. Previously this was taken
214        from the 1000-entry workspace that had been reserved. So now there is no
215        explicit limit, but more stack is used.
217     8. Applied Daniel's patches to solve problems with the import/export magic
218        syntax that is required for Windows, and which was going wrong for the
219        pcreposix and pcrecpp parts of the library. These were overlooked when this
220        problem was solved for the main library.
222     9. There were some crude static tests to avoid integer overflow when computing
223        the size of patterns that contain repeated groups with explicit upper
224        limits. As the maximum quantifier is 65535, the maximum group length was
225        set at 30,000 so that the product of these two numbers did not overflow a
226        32-bit integer. However, it turns out that people want to use groups that
227        are longer than 30,000 bytes (though not repeat them that many times).
228        Change 7.0/17 (the refactoring of the way the pattern size is computed) has
229        made it possible to implement the integer overflow checks in a much more
230        dynamic way, which I have now done. The artificial limitation on group
231        length has been removed - we now have only the limit on the total length of
232        the compiled pattern, which depends on the LINK_SIZE setting.
234    10. Fixed a bug in the documentation for get/copy named substring when
235        duplicate names are permitted. If none of the named substrings are set, the
236        functions return PCRE_ERROR_NOSUBSTRING (7); the doc said they returned an
237        empty string.
239    11. Because Perl interprets \Q...\E at a high level, and ignores orphan \E
240        instances, patterns such as [\Q\E] or [\E] or even [^\E] cause an error,
241        because the ] is interpreted as the first data character and the
242        terminating ] is not found. PCRE has been made compatible with Perl in this
243        regard. Previously, it interpreted [\Q\E] as an empty class, and [\E] could
244        cause memory overwriting.
246    10. Like Perl, PCRE automatically breaks an unlimited repeat after an empty
247        string has been matched (to stop an infinite loop). It was not recognizing
248        a conditional subpattern that could match an empty string if that
249        subpattern was within another subpattern. For example, it looped when
250        trying to match  (((?(1)X|))*)  but it was OK with  ((?(1)X|)*)  where the
251        condition was not nested. This bug has been fixed.
253    12. A pattern like \X?\d or \P{L}?\d in non-UTF-8 mode could cause a backtrack
254        past the start of the subject in the presence of bytes with the top bit
255        set, for example "\x8aBCD".
257    13. Added Perl 5.10 experimental backtracking controls (*FAIL), (*F), (*PRUNE),
258        (*SKIP), (*THEN), (*COMMIT), and (*ACCEPT).
260    14. Optimized (?!) to (*FAIL).
262    15. Updated the test for a valid UTF-8 string to conform to the later RFC 3629.
263        This restricts code points to be within the range 0 to 0x10FFFF, excluding
264        the "low surrogate" sequence 0xD800 to 0xDFFF. Previously, PCRE allowed the
265        full range 0 to 0x7FFFFFFF, as defined by RFC 2279. Internally, it still
266        does: it's just the validity check that is more restrictive.
268    16. Inserted checks for integer overflows during escape sequence (backslash)
269        processing, and also fixed erroneous offset values for syntax errors during
270        backslash processing.
272    17. Fixed another case of looking too far back in non-UTF-8 mode (cf 12 above)
273        for patterns like [\PPP\x8a]{1,}\x80 with the subject "A\x80".
275    18. An unterminated class in a pattern like (?1)\c[ with a "forward reference"
276        caused an overrun.
278    19. A pattern like (?:[\PPa*]*){8,} which had an "extended class" (one with
279        something other than just ASCII characters) inside a group that had an
280        unlimited repeat caused a loop at compile time (while checking to see
281        whether the group could match an empty string).
283    20. Debugging a pattern containing \p or \P could cause a crash. For example,
284        [\P{Any}] did so. (Error in the code for printing property names.)
286    21. An orphan \E inside a character class could cause a crash.
288    22. A repeated capturing bracket such as (A)? could cause a wild memory
289        reference during compilation.
291    23. There are several functions in pcre_compile() that scan along a compiled
292        expression for various reasons (e.g. to see if it's fixed length for look
293        behind). There were bugs in these functions when a repeated \p or \P was
294        present in the pattern. These operators have additional parameters compared
295        with \d, etc, and these were not being taken into account when moving along
296        the compiled data. Specifically:
298        (a) A item such as \p{Yi}{3} in a lookbehind was not treated as fixed
299            length.
301        (b) An item such as \pL+ within a repeated group could cause crashes or
302            loops.
304        (c) A pattern such as \p{Yi}+(\P{Yi}+)(?1) could give an incorrect
305            "reference to non-existent subpattern" error.
307        (d) A pattern like (\P{Yi}{2}\277)? could loop at compile time.
309    24. A repeated \S or \W in UTF-8 mode could give wrong answers when multibyte
310        characters were involved (for example /\S{2}/8g with "A\x{a3}BC").
312    25. Using pcregrep in multiline, inverted mode (-Mv) caused it to loop.
314    26. Patterns such as [\P{Yi}A] which include \p or \P and just one other
315        character were causing crashes (broken optimization).
317    27. Patterns such as (\P{Yi}*\277)* (group with possible zero repeat containing
318        \p or \P) caused a compile-time loop.
320    28. More problems have arisen in unanchored patterns when CRLF is a valid line
321        break. For example, the unstudied pattern [\r\n]A does not match the string
322        "\r\nA" because change 7.0/46 below moves the current point on by two
323        characters after failing to match at the start. However, the pattern \nA
324        *does* match, because it doesn't start till \n, and if [\r\n]A is studied,
325        the same is true. There doesn't seem any very clean way out of this, but
326        what I have chosen to do makes the common cases work: PCRE now takes note
327        of whether there can be an explicit match for \r or \n anywhere in the
328        pattern, and if so, 7.0/46 no longer applies. As part of this change,
329        there's a new PCRE_INFO_HASCRORLF option for finding out whether a compiled
330        pattern has explicit CR or LF references.
332    29. Added (*CR) etc for changing newline setting at start of pattern.
335    Version 7.2 19-Jun-07
336    ---------------------
338     1. If the fr_FR locale cannot be found for test 3, try the "french" locale,
339        which is apparently normally available under Windows.
341     2. Re-jig the pcregrep tests with different newline settings in an attempt
342        to make them independent of the local environment's newline setting.
344     3. Add code to configure.ac to remove -g from the CFLAGS default settings.
346     4. Some of the "internals" tests were previously cut out when the link size
347        was not 2, because the output contained actual offsets. The recent new
348        "Z" feature of pcretest means that these can be cut out, making the tests
349        usable with all link sizes.
351     5. Implemented Stan Switzer's goto replacement for longjmp() when not using
352        stack recursion. This gives a massive performance boost under BSD, but just
353        a small improvement under Linux. However, it saves one field in the frame
354        in all cases.
356     6. Added more features from the forthcoming Perl 5.10:
358        (a) (?-n) (where n is a string of digits) is a relative subroutine or
359            recursion call. It refers to the nth most recently opened parentheses.
361        (b) (?+n) is also a relative subroutine call; it refers to the nth next
362            to be opened parentheses.
364        (c) Conditions that refer to capturing parentheses can be specified
365            relatively, for example, (?(-2)... or (?(+3)...
367        (d) \K resets the start of the current match so that everything before
368            is not part of it.
370        (e) \k{name} is synonymous with \k<name> and \k'name' (.NET compatible).
372        (f) \g{name} is another synonym - part of Perl 5.10's unification of
373            reference syntax.
375        (g) (?| introduces a group in which the numbering of parentheses in each
376            alternative starts with the same number.
378        (h) \h, \H, \v, and \V match horizontal and vertical whitespace.
380     7. Added two new calls to pcre_fullinfo(): PCRE_INFO_OKPARTIAL and
383     8. A pattern such as  (.*(.)?)*  caused pcre_exec() to fail by either not
384        terminating or by crashing. Diagnosed by Viktor Griph; it was in the code
385        for detecting groups that can match an empty string.
387     9. A pattern with a very large number of alternatives (more than several
388        hundred) was running out of internal workspace during the pre-compile
389        phase, where pcre_compile() figures out how much memory will be needed. A
390        bit of new cunning has reduced the workspace needed for groups with
391        alternatives. The 1000-alternative test pattern now uses 12 bytes of
392        workspace instead of running out of the 4096 that are available.
394    10. Inserted some missing (unsigned int) casts to get rid of compiler warnings.
396    11. Applied patch from Google to remove an optimization that didn't quite work.
397        The report of the bug said:
399          pcrecpp::RE("a*").FullMatch("aaa") matches, while
400          pcrecpp::RE("a*?").FullMatch("aaa") does not, and
401          pcrecpp::RE("a*?\\z").FullMatch("aaa") does again.
403    12. If \p or \P was used in non-UTF-8 mode on a character greater than 127
404        it matched the wrong number of bytes.
407    Version 7.1 24-Apr-07
408    ---------------------
410     1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
411        that is more "standard", making use of automake and other Autotools. There
412        is some re-arrangement of the files and adjustment of comments consequent
413        on this.
415     2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
416        for recursive directory scanning broke on some systems because the files
417        are not scanned in any specific order and on different systems the order
418        was different. A call to "sort" has been inserted into RunGrepTest for the
419        approprate test as a short-term fix. In the longer term there may be an
420        alternative.
422     3. I had an email from Eric Raymond about problems translating some of PCRE's
423        man pages to HTML (despite the fact that I distribute HTML pages, some
424        people do their own conversions for various reasons). The problems
425        concerned the use of low-level troff macros .br and .in. I have therefore
426        removed all such uses from the man pages (some were redundant, some could
427        be replaced by .nf/.fi pairs). The 132html script that I use to generate
428        HTML has been updated to handle .nf/.fi and to complain if it encounters
429        .br or .in.
431     4. Updated comments in configure.ac that get placed in config.h.in and also
432        arranged for config.h to be included in the distribution, with the name
433        config.h.generic, for the benefit of those who have to compile without
434        Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
436     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
437        Weber: (1) pcre_internal.h was missing some function renames; (2) updated
438        makevp.bat for the current PCRE, using the additional files
439        makevp_c.txt, makevp_l.txt, and pcregexp.pas.
441     6. A Windows user reported a minor discrepancy with test 2, which turned out
442        to be caused by a trailing space on an input line that had got lost in his
443        copy. The trailing space was an accident, so I've just removed it.
445     7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
446        that is needed.
448     8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
449        as "const" (a) because they are and (b) because it helps the PHP
450        maintainers who have recently made a script to detect big data structures
451        in the php code that should be moved to the .rodata section. I remembered
452        to update Builducptable as well, so it won't revert if ucptable.h is ever
453        re-created.
455     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
456        pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
457        order to be able to cut out the UTF-8 tables in the latter when UTF-8
458        support is not required. This saves 1.5-2K of code, which is important in
459        some applications.
461        Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
462        so as not to refer to the tables, even though these functions will never be
463        called when UTF-8 support is disabled. Otherwise there are problems with a
464        shared library.
466    10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
468        (a) It was defining its arguments as char * instead of void *.
470        (b) It was assuming that all moves were upwards in memory; this was true
471            a long time ago when I wrote it, but is no longer the case.
473        The emulated memove() is provided for those environments that have neither
474        memmove() nor bcopy(). I didn't think anyone used it these days, but that
475        is clearly not the case, as these two bugs were recently reported.
477    11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
478        and Detrail to create the HTML documentation, the .txt form of the man
479        pages, and it removes trailing spaces from listed files. It also creates
480        pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
481        case, it wraps all the #defines with #ifndefs. This script should be run
482        before "make dist".
484    12. Fixed two fairly obscure bugs concerned with quantified caseless matching
485        with Unicode property support.
487        (a) For a maximizing quantifier, if the two different cases of the
488            character were of different lengths in their UTF-8 codings (there are
489            some cases like this - I found 11), and the matching function had to
490            back up over a mixture of the two cases, it incorrectly assumed they
491            were both the same length.
493        (b) When PCRE was configured to use the heap rather than the stack for
494            recursion during matching, it was not correctly preserving the data for
495            the other case of a UTF-8 character when checking ahead for a match
496            while processing a minimizing repeat. If the check also involved
497            matching a wide character, but failed, corruption could cause an
498            erroneous result when trying to check for a repeat of the original
499            character.
501    13. Some tidying changes to the testing mechanism:
503        (a) The RunTest script now detects the internal link size and whether there
504            is UTF-8 and UCP support by running ./pcretest -C instead of relying on
505            values substituted by "configure". (The RunGrepTest script already did
506            this for UTF-8.) The configure.ac script no longer substitutes the
507            relevant variables.
509        (b) The debugging options /B and /D in pcretest show the compiled bytecode
510            with length and offset values. This means that the output is different
511            for different internal link sizes. Test 2 is skipped for link sizes
512            other than 2 because of this, bypassing the problem. Unfortunately,
513            there was also a test in test 3 (the locale tests) that used /B and
514            failed for link sizes other than 2. Rather than cut the whole test out,
515            I have added a new /Z option to pcretest that replaces the length and
516            offset values with spaces. This is now used to make test 3 independent
517            of link size. (Test 2 will be tidied up later.)
519    14. If erroroffset was passed as NULL to pcre_compile, it provoked a
520        segmentation fault instead of returning the appropriate error message.
522    15. In multiline mode when the newline sequence was set to "any", the pattern
523        ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
524        This doesn't seem right; it now treats the CRLF combination as the line
525        ending, and so does not match in that case. It's only a pattern such as ^$
526        that would hit this one: something like ^ABC$ would have failed after \r
527        and then tried again after \r\n.
529    16. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
530        in an attempt to make files that differ only in their line terminators
531        compare equal. This works on Linux.
533    17. Under certain error circumstances pcregrep might try to free random memory
534        as it exited. This is now fixed, thanks to valgrind.
536    19. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
537        "abc\r\n\r\n", it found an unwanted second match after the second \r. This
538        was because its rules for how to advance for /g after matching an empty
539        string at the end of a line did not allow for this case. They now check for
540        it specially.
542    20. pcretest is supposed to handle patterns and data of any length, by
543        extending its buffers when necessary. It was getting this wrong when the
544        buffer for a data line had to be extended.
546    21. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or
547        CRLF as a newline sequence.
549    22. Code for handling Unicode properties in pcre_dfa_exec() wasn't being cut
550        out by #ifdef SUPPORT_UCP. This did no harm, as it could never be used, but
551        I have nevertheless tidied it up.
553    23. Added some casts to kill warnings from HP-UX ia64 compiler.
555    24. Added a man page for pcre-config.
558    Version 7.0 19-Dec-06
559    ---------------------
561     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
562        moving to gcc 4.1.1.
564     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
565        sys/time.h, which is documented as needed for this function. It doesn't
566        seem to matter on Linux, but it showed up on some releases of OS X.
568     3. It seems that there are systems where bytes whose values are greater than
569        127 match isprint() in the "C" locale. The "C" locale should be the
570        default when a C program starts up. In most systems, only ASCII printing
571        characters match isprint(). This difference caused the output from pcretest
572        to vary, making some of the tests fail. I have changed pcretest so that:
574        (a) When it is outputting text in the compiled version of a pattern, bytes
575            other than 32-126 are always shown as hex escapes.
577        (b) When it is outputting text that is a matched part of a subject string,
578            it does the same, unless a different locale has been set for the match
579            (using the /L modifier). In this case, it uses isprint() to decide.
581     4. Fixed a major bug that caused incorrect computation of the amount of memory
582        required for a compiled pattern when options that changed within the
583        pattern affected the logic of the preliminary scan that determines the
584        length. The relevant options are -x, and -i in UTF-8 mode. The result was
585        that the computed length was too small. The symptoms of this bug were
586        either the PCRE error "internal error: code overflow" from pcre_compile(),
587        or a glibc crash with a message such as "pcretest: free(): invalid next
588        size (fast)". Examples of patterns that provoked this bug (shown in
589        pcretest format) are:
591          /(?-x: )/x
592          /(?x)(?-x: \s*#\s*)/
593          /((?i)[\x{c0}])/8
594          /(?i:[\x{c0}])/8
596        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
597        is now done differently.
599     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
600        wrapper classes; (b) implement a new function in the C++ scanner that is
601        more efficient than the old way of doing things because it avoids levels of
602        recursion in the regex matching; (c) add a paragraph to the documentation
603        for the FullMatch() function.
605     6. The escape sequence \n was being treated as whatever was defined as
606        "newline". Not only was this contrary to the documentation, which states
607        that \n is character 10 (hex 0A), but it also went horribly wrong when
608        "newline" was defined as CRLF. This has been fixed.
610     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
611        was being set to -1 for the "end of line" case (supposedly a value that no
612        character can have). Though this value is never used (the check for end of
613        line is "zero bytes in current character"), it caused compiler complaints.
614        I've changed it to 0xffffffff.
616     8. In pcre_version.c, the version string was being built by a sequence of
617        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
618        string (as it is for production releases) called a macro with an empty
619        argument. The C standard says the result of this is undefined. The gcc
620        compiler treats it as an empty string (which was what was wanted) but it is
621        reported that Visual C gives an error. The source has been hacked around to
622        avoid this problem.
624     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
625        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
626        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
627        of them did).
629    10. Originally, pcretest opened its input and output without "b"; then I was
630        told that "b" was needed in some environments, so it was added for release
631        5.0 to both the input and output. (It makes no difference on Unix-like
632        systems.) Later I was told that it is wrong for the input on Windows. I've
633        now abstracted the modes into two macros, to make it easier to fiddle with
634        them, and removed "b" from the input mode under Windows.
636    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
638    12. Added -help and --help to pcretest as an official way of being reminded
639        of the options.
641    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
642        and pcrecpp.cc because they annoy compilers at high warning levels.
644    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
646    15. Fixed an occurrence of == in configure.ac that should have been = (shell
647        scripts are not C programs :-) and which was not noticed because it works
648        on Linux.
650    16. pcretest is supposed to handle any length of pattern and data line (as one
651        line or as a continued sequence of lines) by extending its input buffer if
652        necessary. This feature was broken for very long pattern lines, leading to
653        a string of junk being passed to pcre_compile() if the pattern was longer
654        than about 50K.
656    17. I have done a major re-factoring of the way pcre_compile() computes the
657        amount of memory needed for a compiled pattern. Previously, there was code
658        that made a preliminary scan of the pattern in order to do this. That was
659        OK when PCRE was new, but as the facilities have expanded, it has become
660        harder and harder to keep it in step with the real compile phase, and there
661        have been a number of bugs (see for example, 4 above). I have now found a
662        cunning way of running the real compile function in a "fake" mode that
663        enables it to compute how much memory it would need, while actually only
664        ever using a few hundred bytes of working memory and without too many
665        tests of the mode. This should make future maintenance and development
666        easier. A side effect of this work is that the limit of 200 on the nesting
667        depth of parentheses has been removed (though this was never a serious
668        limitation, I suspect). However, there is a downside: pcre_compile() now
669        runs more slowly than before (30% or more, depending on the pattern). I
670        hope this isn't a big issue. There is no effect on runtime performance.
672    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
673        newline (only possible for the last line of a file) and it was a
674        pattern that set a locale (followed by /Lsomething), pcretest crashed.
676    19. Added additional timing features to pcretest. (1) The -tm option now times
677        matching only, not compiling. (2) Both -t and -tm can be followed, as a
678        separate command line item, by a number that specifies the number of
679        repeats to use when timing. The default is 50000; this gives better
680        precision, but takes uncomfortably long for very large patterns.
682    20. Extended pcre_study() to be more clever in cases where a branch of a
683        subpattern has no definite first character. For example, (a*|b*)[cd] would
684        previously give no result from pcre_study(). Now it recognizes that the
685        first character must be a, b, c, or d.
687    21. There was an incorrect error "recursive call could loop indefinitely" if
688        a subpattern (or the entire pattern) that was being tested for matching an
689        empty string contained only one non-empty item after a nested subpattern.
690        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
691        incorrectly, because the \d was being skipped in the check.
693    22. The pcretest program now has a new pattern option /B and a command line
694        option -b, which is equivalent to adding /B to every pattern. This causes
695        it to show the compiled bytecode, without the additional information that
696        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
697        is the same as /B/I).
699    23. A new optimization is now able automatically to treat some sequences such
700        as a*b as a*+b. More specifically, if something simple (such as a character
701        or a simple class like \d) has an unlimited quantifier, and is followed by
702        something that cannot possibly match the quantified thing, the quantifier
703        is automatically "possessified".
705    24. A recursive reference to a subpattern whose number was greater than 39
706        went wrong under certain circumstances in UTF-8 mode. This bug could also
707        have affected the operation of pcre_study().
709    25. Realized that a little bit of performance could be had by replacing
710        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
712    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
714    27. Possessive quantifiers such as a++ were previously implemented by turning
715        them into atomic groups such as ($>a+). Now they have their own opcodes,
716        which improves performance. This includes the automatically created ones
717        from 23 above.
719    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
720        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
721        the first matched character to be a colon. This applied both to named and
722        numbered groups.
724    29. The ucpinternal.h header file was missing its idempotency #ifdef.
726    30. I was sent a "project" file called libpcre.a.dev which I understand makes
727        building PCRE on Windows easier, so I have included it in the distribution.
729    31. There is now a check in pcretest against a ridiculously large number being
730        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
731        loop, the loop is abandoned.
733    32. Forward references to subpatterns in conditions such as (?(2)...) where
734        subpattern 2 is defined later cause pcre_compile() to search forwards in
735        the pattern for the relevant set of parentheses. This search went wrong
736        when there were unescaped parentheses in a character class, parentheses
737        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
739    33. "Subroutine" calls and backreferences were previously restricted to
740        referencing subpatterns earlier in the regex. This restriction has now
741        been removed.
743    34. Added a number of extra features that are going to be in Perl 5.10. On the
744        whole, these are just syntactic alternatives for features that PCRE had
745        previously implemented using the Python syntax or my own invention. The
746        other formats are all retained for compatibility.
748        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
749            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
750            also .NET compatible.
752        (b) A recursion or subroutine call to a named group can now be defined as
753            (?&name) as well as (?P>name).
755        (c) A backreference to a named group can now be defined as \k<name> or
756            \k'name' as well as (?P=name). The new forms, as well as being in Perl
757            5.10, are also .NET compatible.
759        (d) A conditional reference to a named group can now use the syntax
760            (?(<name>) or (?('name') as well as (?(name).
762        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
763            groups (named and numbered) that are never evaluated inline, but can be
764            called as "subroutines" from elsewhere. In effect, the DEFINE condition
765            is always false. There may be only one alternative in such a group.
767        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
768            as the simple (?(R). The condition is true only if the most recent
769            recursion is that of the given number or name. It does not search out
770            through the entire recursion stack.
772        (g) The escape \gN or \g{N} has been added, where N is a positive or
773            negative number, specifying an absolute or relative reference.
775    35. Tidied to get rid of some further signed/unsigned compiler warnings and
776        some "unreachable code" warnings.
778    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
779        things, this adds five new scripts.
781    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
782        There were also incompatibilities regarding the handling of \Q..\E inside
783        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
784        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
786    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
787        matches an empty string, and forcibly breaks the loop. There were bugs in
788        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
789        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
790        separate and independent bugs (that affected different cases) have been
791        fixed.
793    39. Refactored the code to abolish the use of different opcodes for small
794        capturing bracket numbers. This is a tidy that I avoided doing when I
795        removed the limit on the number of capturing brackets for 3.5 back in 2001.
796        The new approach is not only tidier, it makes it possible to reduce the
797        memory needed to fix the previous bug (38).
799    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
800        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
801        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
802        mode.
804    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
805        report.
807    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
808        copy construction and assignment in the C++ wrapper.
810    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
811        couple of bugs that could have given wrong results in the "--newline=crlf"
812        case.
814    44. Added a number of casts and did some reorganization of signed/unsigned int
815        variables following suggestions from Dair Grant. Also renamed the variable
816        "this" as "item" because it is a C++ keyword.
818    45. Arranged for dftables to add
820          #include "pcre_internal.h"
822        to pcre_chartables.c because without it, gcc 4.x may remove the array
823        definition from the final binary if PCRE is built into a static library and
824        dead code stripping is activated.
826    46. For an unanchored pattern, if a match attempt fails at the start of a
827        newline sequence, and the newline setting is CRLF or ANY, and the next two
828        characters are CRLF, advance by two characters instead of one.
831    Version 6.7 04-Jul-06
832    ---------------------
834     1. In order to handle tests when input lines are enormously long, pcretest has
835        been re-factored so that it automatically extends its buffers when
836        necessary. The code is crude, but this _is_ just a test program. The
837        default size has been increased from 32K to 50K.
839     2. The code in pcre_study() was using the value of the re argument before
840        testing it for NULL. (Of course, in any sensible call of the function, it
841        won't be NULL.)
843     3. The memmove() emulation function in pcre_internal.h, which is used on
844        systems that lack both memmove() and bcopy() - that is, hardly ever -
845        was missing a "static" storage class specifier.
847     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
848        containing an extended class (one that cannot be represented by a bitmap
849        because it contains high-valued characters or Unicode property items, e.g.
850        [\pZ]). Almost always one would set UTF-8 mode when processing such a
851        pattern, but PCRE should not loop if you do not (it no longer does).
852        [Detail: two cases were found: (a) a repeated subpattern containing an
853        extended class; (b) a recursive reference to a subpattern that followed a
854        previous extended class. It wasn't skipping over the extended class
855        correctly when UTF-8 mode was not set.]
857     5. A negated single-character class was not being recognized as fixed-length
858        in lookbehind assertions such as (?<=[^f]), leading to an incorrect
859        compile error "lookbehind assertion is not fixed length".
861     6. The RunPerlTest auxiliary script was showing an unexpected difference
862        between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
863        write a Perl script that can interpret lines of an input file either as
864        byte characters or as UTF-8, which is what "perltest" was being required to
865        do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
866        can't do is switch easily at run time between having the "use utf8;" pragma
867        or not. In the end, I fudged it by using the RunPerlTest script to insert
868        "use utf8;" explicitly for the UTF-8 tests.
870     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
871        the end of the subject string, contrary to the documentation and to what
872        Perl does. This was true of both matching functions. Now it matches only at
873        the start of the subject and immediately after *internal* newlines.
875     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
876        a pointer to an int instead of a pointer to an unsigned long int. This
877        caused problems on 64-bit systems.
879     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
880        instance of the 'standard' template library not being so standard".
882    10. There was no check on the number of named subpatterns nor the maximum
883        length of a subpattern name. The product of these values is used to compute
884        the size of the memory block for a compiled pattern. By supplying a very
885        long subpattern name and a large number of named subpatterns, the size
886        computation could be caused to overflow. This is now prevented by limiting
887        the length of names to 32 characters, and the number of named subpatterns
888        to 10,000.
890    11. Subpatterns that are repeated with specific counts have to be replicated in
891        the compiled pattern. The size of memory for this was computed from the
892        length of the subpattern and the repeat count. The latter is limited to
893        65535, but there was no limit on the former, meaning that integer overflow
894        could in principle occur. The compiled length of a repeated subpattern is
895        now limited to 30,000 bytes in order to prevent this.
897    12. Added the optional facility to have named substrings with the same name.
899    13. Added the ability to use a named substring as a condition, using the
900        Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
901        are numbers (not recommended). Forward references are permitted.
903    14. Added forward references in named backreferences (if you see what I mean).
905    15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
906        pattern could run off the end of the subject. For example, the pattern
907        "(?s)(.{1,5})"8 did this with the subject "ab".
909    16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
910        PCRE_CASELESS was set when matching characters that were quantified with ?
911        or *.
913    17. A character class other than a single negated character that had a minimum
914        but no maximum quantifier - for example [ab]{6,} - was not handled
915        correctly by pce_dfa_exec(). It would match only one character.
917    18. A valid (though odd) pattern that looked like a POSIX character
918        class but used an invalid character after [ (for example [[,abc,]]) caused
919        pcre_compile() to give the error "Failed: internal error: code overflow" or
920        in some cases to crash with a glibc free() error. This could even happen if
921        the pattern terminated after [[ but there just happened to be a sequence of
922        letters, a binary zero, and a closing ] in the memory that followed.
924    19. Perl's treatment of octal escapes in the range \400 to \777 has changed
925        over the years. Originally (before any Unicode support), just the bottom 8
926        bits were taken. Thus, for example, \500 really meant \100. Nowadays the
927        output from "man perlunicode" includes this:
929          The regular expression compiler produces polymorphic opcodes.  That
930          is, the pattern adapts to the data and automatically switches to
931          the Unicode character scheme when presented with Unicode data--or
932          instead uses a traditional byte scheme when presented with byte
933          data.
935        Sadly, a wide octal escape does not cause a switch, and in a string with
936        no other multibyte characters, these octal escapes are treated as before.
937        Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
938        /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
939        Unicode string.
941        I have not perpetrated such confusion in PCRE. Up till now, it took just
942        the bottom 8 bits, as in old Perl. I have now made octal escapes with
943        values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
944        translate to the appropriate multibyte character.
946    29. Applied some refactoring to reduce the number of warnings from Microsoft
947        and Borland compilers. This has included removing the fudge introduced
948        seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
949        a warning about an unused variable.
951    21. PCRE has not included VT (character 0x0b) in the set of whitespace
952        characters since release 4.0, because Perl (from release 5.004) does not.
953        [Or at least, is documented not to: some releases seem to be in conflict
954        with the documentation.] However, when a pattern was studied with
955        pcre_study() and all its branches started with \s, PCRE still included VT
956        as a possible starting character. Of course, this did no harm; it just
957        caused an unnecessary match attempt.
959    22. Removed a now-redundant internal flag bit that recorded the fact that case
960        dependency changed within the pattern. This was once needed for "required
961        byte" processing, but is no longer used. This recovers a now-scarce options
962        bit. Also moved the least significant internal flag bit to the most-
963        significant bit of the word, which was not previously used (hangover from
964        the days when it was an int rather than a uint) to free up another bit for
965        the future.
967    23. Added support for CRLF line endings as well as CR and LF. As well as the
968        default being selectable at build time, it can now be changed at runtime
969        via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
970        specify that it is scanning data with non-default line endings.
972    24. Changed the definition of CXXLINK to make it agree with the definition of
973        LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
975    25. Applied Ian Taylor's patches to avoid using another stack frame for tail
976        recursions. This makes a big different to stack usage for some patterns.
978    26. If a subpattern containing a named recursion or subroutine reference such
979        as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
980        the space required for the compiled pattern went wrong and gave too small a
981        value. Depending on the environment, this could lead to "Failed: internal
982        error: code overflow at offset 49" or "glibc detected double free or
983        corruption" errors.
985    27. Applied patches from Google (a) to support the new newline modes and (b) to
986        advance over multibyte UTF-8 characters in GlobalReplace.
988    28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
989        difference for some implementation of PCRE in some Windows version.
991    29. Added some extra testing facilities to pcretest:
993        \q<number>   in a data line sets the "match limit" value
994        \Q<number>   in a data line sets the "match recursion limt" value
995        -S <number>  sets the stack size, where <number> is in megabytes
997        The -S option isn't available for Windows.
1000    Version 6.6 06-Feb-06
1001    ---------------------
1003     1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
1004        in pcreposix.h. I have copied the definition from pcre.h.
1006     2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
1007        because pcre.h is no longer a built file.
1009     3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
1010        not normally included in the compiled code.
1013    Version 6.5 01-Feb-06
1014    ---------------------
1016     1. When using the partial match feature with pcre_dfa_exec(), it was not
1017        anchoring the second and subsequent partial matches at the new starting
1018        point. This could lead to incorrect results. For example, with the pattern
1019        /1234/, partially matching against "123" and then "a4" gave a match.
1021     2. Changes to pcregrep:
1023        (a) All non-match returns from pcre_exec() were being treated as failures
1024            to match the line. Now, unless the error is PCRE_ERROR_NOMATCH, an
1025            error message is output. Some extra information is given for the
1026            PCRE_ERROR_MATCHLIMIT and PCRE_ERROR_RECURSIONLIMIT errors, which are
1027            probably the only errors that are likely to be caused by users (by
1028            specifying a regex that has nested indefinite repeats, for instance).
1029            If there are more than 20 of these errors, pcregrep is abandoned.
1031        (b) A binary zero was treated as data while matching, but terminated the
1032            output line if it was written out. This has been fixed: binary zeroes
1033            are now no different to any other data bytes.
1035        (c) Whichever of the LC_ALL or LC_CTYPE environment variables is set is
1036            used to set a locale for matching. The --locale=xxxx long option has
1037            been added (no short equivalent) to specify a locale explicitly on the
1038            pcregrep command, overriding the environment variables.
1040        (d) When -B was used with -n, some line numbers in the output were one less
1041            than they should have been.
1043        (e) Added the -o (--only-matching) option.
1045        (f) If -A or -C was used with -c (count only), some lines of context were
1046            accidentally printed for the final match.
1048        (g) Added the -H (--with-filename) option.
1050        (h) The combination of options -rh failed to suppress file names for files
1051            that were found from directory arguments.
1053        (i) Added the -D (--devices) and -d (--directories) options.
1055        (j) Added the -F (--fixed-strings) option.
1057        (k) Allow "-" to be used as a file name for -f as well as for a data file.
1059        (l) Added the --colo(u)r option.
1061        (m) Added Jeffrey Friedl's -S testing option, but within #ifdefs so that it
1062            is not present by default.
1064     3. A nasty bug was discovered in the handling of recursive patterns, that is,
1065        items such as (?R) or (?1), when the recursion could match a number of
1066        alternatives. If it matched one of the alternatives, but subsequently,
1067        outside the recursion, there was a failure, the code tried to back up into
1068        the recursion. However, because of the way PCRE is implemented, this is not
1069        possible, and the result was an incorrect result from the match.
1071        In order to prevent this happening, the specification of recursion has
1072        been changed so that all such subpatterns are automatically treated as
1073        atomic groups. Thus, for example, (?R) is treated as if it were (?>(?R)).
1075     4. I had overlooked the fact that, in some locales, there are characters for
1076        which isalpha() is true but neither isupper() nor islower() are true. In
1077        the fr_FR locale, for instance, the \xAA and \xBA characters (ordmasculine
1078        and ordfeminine) are like this. This affected the treatment of \w and \W
1079        when they appeared in character classes, but not when they appeared outside
1080        a character class. The bit map for "word" characters is now created
1081        separately from the results of isalnum() instead of just taking it from the
1082        upper, lower, and digit maps. (Plus the underscore character, of course.)
1084     5. The above bug also affected the handling of POSIX character classes such as
1085        [[:alpha:]] and [[:alnum:]]. These do not have their own bit maps in PCRE's
1086        permanent tables. Instead, the bit maps for such a class were previously
1087        created as the appropriate unions of the upper, lower, and digit bitmaps.
1088        Now they are created by subtraction from the [[:word:]] class, which has
1089        its own bitmap.
1091     6. The [[:blank:]] character class matches horizontal, but not vertical space.
1092        It is created by subtracting the vertical space characters (\x09, \x0a,
1093        \x0b, \x0c) from the [[:space:]] bitmap. Previously, however, the
1094        subtraction was done in the overall bitmap for a character class, meaning
1095        that a class such as [\x0c[:blank:]] was incorrect because \x0c would not
1096        be recognized. This bug has been fixed.
1098     7. Patches from the folks at Google:
1100          (a) pcrecpp.cc: "to handle a corner case that may or may not happen in
1101          real life, but is still worth protecting against".
1103          (b) pcrecpp.cc: "corrects a bug when negative radixes are used with
1104          regular expressions".
1106          (c) pcre_scanner.cc: avoid use of std::count() because not all systems
1107          have it.
1109          (d) Split off pcrecpparg.h from pcrecpp.h and had the former built by
1110          "configure" and the latter not, in order to fix a problem somebody had
1111          with compiling the Arg class on HP-UX.
1113          (e) Improve the error-handling of the C++ wrapper a little bit.
1115          (f) New tests for checking recursion limiting.
1117     8. The pcre_memmove() function, which is used only if the environment does not
1118        have a standard memmove() function (and is therefore rarely compiled),
1119        contained two bugs: (a) use of int instead of size_t, and (b) it was not
1120        returning a result (though PCRE never actually uses the result).
1122     9. In the POSIX regexec() interface, if nmatch is specified as a ridiculously
1123        large number - greater than INT_MAX/(3*sizeof(int)) - REG_ESPACE is
1124        returned instead of calling malloc() with an overflowing number that would
1125        most likely cause subsequent chaos.
1127    10. The debugging option of pcretest was not showing the NO_AUTO_CAPTURE flag.
1129    11. The POSIX flag REG_NOSUB is now supported. When a pattern that was compiled
1130        with this option is matched, the nmatch and pmatch options of regexec() are
1131        ignored.
1133    12. Added REG_UTF8 to the POSIX interface. This is not defined by POSIX, but is
1134        provided in case anyone wants to the the POSIX interface with UTF-8
1135        strings.
1137    13. Added CXXLDFLAGS to the Makefile parameters to provide settings only on the
1138        C++ linking (needed for some HP-UX environments).
1140    14. Avoid compiler warnings in get_ucpname() when compiled without UCP support
1141        (unused parameter) and in the pcre_printint() function (omitted "default"
1142        switch label when the default is to do nothing).
1144    15. Added some code to make it possible, when PCRE is compiled as a C++
1145        library, to replace subject pointers for pcre_exec() with a smart pointer
1146        class, thus making it possible to process discontinuous strings.
1148    16. The two macros PCRE_EXPORT and PCRE_DATA_SCOPE are confusing, and perform
1149        much the same function. They were added by different people who were trying
1150        to make PCRE easy to compile on non-Unix systems. It has been suggested
1151        that PCRE_EXPORT be abolished now that there is more automatic apparatus
1152        for compiling on Windows systems. I have therefore replaced it with
1153        PCRE_DATA_SCOPE. This is set automatically for Windows; if not set it
1154        defaults to "extern" for C or "extern C" for C++, which works fine on
1155        Unix-like systems. It is now possible to override the value of PCRE_DATA_
1156        SCOPE with something explicit in config.h. In addition:
1158        (a) pcreposix.h still had just "extern" instead of either of these macros;
1159            I have replaced it with PCRE_DATA_SCOPE.
1161        (b) Functions such as _pcre_xclass(), which are internal to the library,
1162            but external in the C sense, all had PCRE_EXPORT in their definitions.
1163            This is apparently wrong for the Windows case, so I have removed it.
1164            (It makes no difference on Unix-like systems.)
1166    17. Added a new limit, MATCH_LIMIT_RECURSION, which limits the depth of nesting
1167        of recursive calls to match(). This is different to MATCH_LIMIT because
1168        that limits the total number of calls to match(), not all of which increase
1169        the depth of recursion. Limiting the recursion depth limits the amount of
1170        stack (or heap if NO_RECURSE is set) that is used. The default can be set
1171        when PCRE is compiled, and changed at run time. A patch from Google adds
1172        this functionality to the C++ interface.
1174    18. Changes to the handling of Unicode character properties:
1176        (a) Updated the table to Unicode 4.1.0.
1178        (b) Recognize characters that are not in the table as "Cn" (undefined).
1180        (c) I revised the way the table is implemented to a much improved format
1181            which includes recognition of ranges. It now supports the ranges that
1182            are defined in UnicodeData.txt, and it also amalgamates other
1183            characters into ranges. This has reduced the number of entries in the
1184            table from around 16,000 to around 3,000, thus reducing its size
1185            considerably. I realized I did not need to use a tree structure after
1186            all - a binary chop search is just as efficient. Having reduced the
1187            number of entries, I extended their size from 6 bytes to 8 bytes to
1188            allow for more data.
1190        (d) Added support for Unicode script names via properties such as \p{Han}.
1192    19. In UTF-8 mode, a backslash followed by a non-Ascii character was not
1193        matching that character.
1195    20. When matching a repeated Unicode property with a minimum greater than zero,
1196        (for example \pL{2,}), PCRE could look past the end of the subject if it
1197        reached it while seeking the minimum number of characters. This could
1198        happen only if some of the characters were more than one byte long, because
1199        there is a check for at least the minimum number of bytes.
1201    21. Refactored the implementation of \p and \P so as to be more general, to
1202        allow for more different types of property in future. This has changed the
1203        compiled form incompatibly. Anybody with saved compiled patterns that use
1204        \p or \P will have to recompile them.
1206    22. Added "Any" and "L&" to the supported property types.
1208    23. Recognize \x{...} as a code point specifier, even when not in UTF-8 mode,
1209        but give a compile time error if the value is greater than 0xff.
1211    24. The man pages for pcrepartial, pcreprecompile, and pcre_compile2 were
1212        accidentally not being installed or uninstalled.
1214    25. The pcre.h file was built from pcre.h.in, but the only changes that were
1215        made were to insert the current release number. This seemed silly, because
1216        it made things harder for people building PCRE on systems that don't run
1217        "configure". I have turned pcre.h into a distributed file, no longer built
1218        by "configure", with the version identification directly included. There is
1219        no longer a pcre.h.in file.
1221        However, this change necessitated a change to the pcre-config script as
1222        well. It is built from pcre-config.in, and one of the substitutions was the
1223        release number. I have updated configure.ac so that ./configure now finds
1224        the release number by grepping pcre.h.
1226    26. Added the ability to run the tests under valgrind.
1229    Version 6.4 05-Sep-05
1230    ---------------------
1232     1. Change 6.0/10/(l) to pcregrep introduced a bug that caused separator lines
1233        "--" to be printed when multiple files were scanned, even when none of the
1234        -A, -B, or -C options were used. This is not compatible with Gnu grep, so I
1235        consider it to be a bug, and have restored the previous behaviour.
1237     2. A couple of code tidies to get rid of compiler warnings.
1239     3. The pcretest program used to cheat by referring to symbols in the library
1240        whose names begin with _pcre_. These are internal symbols that are not
1241        really supposed to be visible externally, and in some environments it is
1242        possible to suppress them. The cheating is now confined to including
1243        certain files from the library's source, which is a bit cleaner.
1245     4. Renamed pcre.in as pcre.h.in to go with pcrecpp.h.in; it also makes the
1246        file's purpose clearer.
1248     5. Reorganized pcre_ucp_findchar().
1251    Version 6.3 15-Aug-05
1252    ---------------------
1254     1. The file libpcre.pc.in did not have general read permission in the tarball.
1256     2. There were some problems when building without C++ support:
1258        (a) If C++ support was not built, "make install" and "make test" still
1259            tried to test it.
1261        (b) There were problems when the value of CXX was explicitly set. Some
1262            changes have been made to try to fix these, and ...
1264        (c) --disable-cpp can now be used to explicitly disable C++ support.
1266        (d) The use of @CPP_OBJ@ directly caused a blank line preceded by a
1267            backslash in a target when C++ was disabled. This confuses some
1268            versions of "make", apparently. Using an intermediate variable solves
1269            this. (Same for CPP_LOBJ.)
1271     3. $(LINK_FOR_BUILD) now includes $(CFLAGS_FOR_BUILD) and $(LINK)
1272        (non-Windows) now includes $(CFLAGS) because these flags are sometimes
1273        necessary on certain architectures.
1275     4. Added a setting of -export-symbols-regex to the link command to remove
1276        those symbols that are exported in the C sense, but actually are local
1277        within the library, and not documented. Their names all begin with
1278        "_pcre_". This is not a perfect job, because (a) we have to except some
1279        symbols that pcretest ("illegally") uses, and (b) the facility isn't always
1280        available (and never for static libraries). I have made a note to try to
1281        find a way round (a) in the future.
1284    Version 6.2 01-Aug-05
1285    ---------------------
1287     1. There was no test for integer overflow of quantifier values. A construction
1288        such as {1111111111111111} would give undefined results. What is worse, if
1289        a minimum quantifier for a parenthesized subpattern overflowed and became
1290        negative, the calculation of the memory size went wrong. This could have
1291        led to memory overwriting.
1293     2. Building PCRE using VPATH was broken. Hopefully it is now fixed.
1295     3. Added "b" to the 2nd argument of fopen() in dftables.c, for non-Unix-like
1296        operating environments where this matters.
1298     4. Applied Giuseppe Maxia's patch to add additional features for controlling
1299        PCRE options from within the C++ wrapper.
1301     5. Named capturing subpatterns were not being correctly counted when a pattern
1302        was compiled. This caused two problems: (a) If there were more than 100
1303        such subpatterns, the calculation of the memory needed for the whole
1304        compiled pattern went wrong, leading to an overflow error. (b) Numerical
1305        back references of the form \12, where the number was greater than 9, were
1306        not recognized as back references, even though there were sufficient
1307        previous subpatterns.
1309     6. Two minor patches to pcrecpp.cc in order to allow it to compile on older
1310        versions of gcc, e.g. 2.95.4.
1313    Version 6.1 21-Jun-05
1314    ---------------------
1316     1. There was one reference to the variable "posix" in pcretest.c that was not
1317        surrounded by "#if !defined NOPOSIX".
1319     2. Make it possible to compile pcretest without DFA support, UTF8 support, or
1320        the cross-check on the old pcre_info() function, for the benefit of the
1321        cut-down version of PCRE that is currently imported into Exim.
1323     3. A (silly) pattern starting with (?i)(?-i) caused an internal space
1324        allocation error. I've done the easy fix, which wastes 2 bytes for sensible
1325        patterns that start (?i) but I don't think that matters. The use of (?i) is
1326        just an example; this all applies to the other options as well.
1328     4. Since libtool seems to echo the compile commands it is issuing, the output
1329        from "make" can be reduced a bit by putting "@" in front of each libtool
1330        compile command.
1332     5. Patch from the folks at Google for configure.in to be a bit more thorough
1333        in checking for a suitable C++ installation before trying to compile the
1334        C++ stuff. This should fix a reported problem when a compiler was present,
1335        but no suitable headers.
1337     6. The man pages all had just "PCRE" as their title. I have changed them to
1338        be the relevant file name. I have also arranged that these names are
1339        retained in the file doc/pcre.txt, which is a concatenation in text format
1340        of all the man pages except the little individual ones for each function.
1342     7. The NON-UNIX-USE file had not been updated for the different set of source
1343        files that come with release 6. I also added a few comments about the C++
1344        wrapper.
1347    Version 6.0 07-Jun-05
1348    ---------------------
1350     1. Some minor internal re-organization to help with my DFA experiments.
1352     2. Some missing #ifdef SUPPORT_UCP conditionals in pcretest and printint that
1353        didn't matter for the library itself when fully configured, but did matter
1354        when compiling without UCP support, or within Exim, where the ucp files are
1355        not imported.
1357     3. Refactoring of the library code to split up the various functions into
1358        different source modules. The addition of the new DFA matching code (see
1359        below) to a single monolithic source would have made it really too
1360        unwieldy, quite apart from causing all the code to be include in a
1361        statically linked application, when only some functions are used. This is
1362        relevant even without the DFA addition now that patterns can be compiled in
1363        one application and matched in another.
1365        The downside of splitting up is that there have to be some external
1366        functions and data tables that are used internally in different modules of
1367        the library but which are not part of the API. These have all had their
1368        names changed to start with "_pcre_" so that they are unlikely to clash
1369        with other external names.
1371     4. Added an alternate matching function, pcre_dfa_exec(), which matches using
1372        a different (DFA) algorithm. Although it is slower than the original
1373        function, it does have some advantages for certain types of matching
1374        problem.
1376     5. Upgrades to pcretest in order to test the features of pcre_dfa_exec(),
1377        including restarting after a partial match.
1379     6. A patch for pcregrep that defines INVALID_FILE_ATTRIBUTES if it is not
1380        defined when compiling for Windows was sent to me. I have put it into the
1381        code, though I have no means of testing or verifying it.
1383     7. Added the pcre_refcount() auxiliary function.
1385     8. Added the PCRE_FIRSTLINE option. This constrains an unanchored pattern to
1386        match before or at the first newline in the subject string. In pcretest,
1387        the /f option on a pattern can be used to set this.
1389     9. A repeated \w when used in UTF-8 mode with characters greater than 256
1390        would behave wrongly. This has been present in PCRE since release 4.0.
1392    10. A number of changes to the pcregrep command:
1394        (a) Refactored how -x works; insert ^(...)$ instead of setting
1395            PCRE_ANCHORED and checking the length, in preparation for adding
1396            something similar for -w.
1398        (b) Added the -w (match as a word) option.
1400        (c) Refactored the way lines are read and buffered so as to have more
1401            than one at a time available.
1403        (d) Implemented a pcregrep test script.
1405        (e) Added the -M (multiline match) option. This allows patterns to match
1406            over several lines of the subject. The buffering ensures that at least
1407            8K, or the rest of the document (whichever is the shorter) is available
1408            for matching (and similarly the previous 8K for lookbehind assertions).
1410        (f) Changed the --help output so that it now says
1412              -w, --word-regex(p)
1414            instead of two lines, one with "regex" and the other with "regexp"
1415            because that confused at least one person since the short forms are the
1416            same. (This required a bit of code, as the output is generated
1417            automatically from a table. It wasn't just a text change.)
1419        (g) -- can be used to terminate pcregrep options if the next thing isn't an
1420            option but starts with a hyphen. Could be a pattern or a path name
1421            starting with a hyphen, for instance.
1423        (h) "-" can be given as a file name to represent stdin.
1425        (i) When file names are being printed, "(standard input)" is used for
1426            the standard input, for compatibility with GNU grep. Previously
1427            "<stdin>" was used.
1429        (j) The option --label=xxx can be used to supply a name to be used for
1430            stdin when file names are being printed. There is no short form.
1432        (k) Re-factored the options decoding logic because we are going to add
1433            two more options that take data. Such options can now be given in four
1434            different ways, e.g. "-fname", "-f name", "--file=name", "--file name".
1436        (l) Added the -A, -B, and -C options for requesting that lines of context
1437            around matches be printed.
1439        (m) Added the -L option to print the names of files that do not contain
1440            any matching lines, that is, the complement of -l.
1442        (n) The return code is 2 if any file cannot be opened, but pcregrep does
1443            continue to scan other files.
1445        (o) The -s option was incorrectly implemented. For compatibility with other
1446            greps, it now suppresses the error message for a non-existent or non-
1447            accessible file (but not the return code). There is a new option called
1448            -q that suppresses the output of matching lines, which was what -s was
1449            previously doing.
1451        (p) Added --include and --exclude options to specify files for inclusion
1452            and exclusion when recursing.
1454    11. The Makefile was not using the Autoconf-supported LDFLAGS macro properly.
1455        Hopefully, it now does.
1457    12. Missing cast in pcre_study().
1459    13. Added an "uninstall" target to the makefile.
1461    14. Replaced "extern" in the function prototypes in Makefile.in with
1462        "PCRE_DATA_SCOPE", which defaults to 'extern' or 'extern "C"' in the Unix
1463        world, but is set differently for Windows.
1465    15. Added a second compiling function called pcre_compile2(). The only
1466        difference is that it has an extra argument, which is a pointer to an
1467        integer error code. When there is a compile-time failure, this is set
1468        non-zero, in addition to the error test pointer being set to point to an
1469        error message. The new argument may be NULL if no error number is required
1470        (but then you may as well call pcre_compile(), which is now just a
1471        wrapper). This facility is provided because some applications need a
1472        numeric error indication, but it has also enabled me to tidy up the way
1473        compile-time errors are handled in the POSIX wrapper.
1475    16. Added VPATH=.libs to the makefile; this should help when building with one
1476        prefix path and installing with another. (Or so I'm told by someone who
1477        knows more about this stuff than I do.)
1479    17. Added a new option, REG_DOTALL, to the POSIX function regcomp(). This
1480        passes PCRE_DOTALL to the pcre_compile() function, making the "." character
1481        match everything, including newlines. This is not POSIX-compatible, but
1482        somebody wanted the feature. From pcretest it can be activated by using
1483        both the P and the s flags.
1485    18. AC_PROG_LIBTOOL appeared twice in Makefile.in. Removed one.
1487    19. libpcre.pc was being incorrectly installed as executable.
1489    20. A couple of places in pcretest check for end-of-line by looking for '\n';
1490        it now also looks for '\r' so that it will work unmodified on Windows.
1492    21. Added Google's contributed C++ wrapper to the distribution.
1494    22. Added some untidy missing memory free() calls in pcretest, to keep
1495        Electric Fence happy when testing.
1499    Version 5.0 13-Sep-04
1500    ---------------------
1502     1. Internal change: literal characters are no longer packed up into items
1503        containing multiple characters in a single byte-string. Each character
1504        is now matched using a separate opcode. However, there may be more than one
1505        byte in the character in UTF-8 mode.
1507     2. The pcre_callout_block structure has two new fields: pattern_position and
1508        next_item_length. These contain the offset in the pattern to the next match
1509        item, and its length, respectively.
1511     3. The PCRE_AUTO_CALLOUT option for pcre_compile() requests the automatic
1512        insertion of callouts before each pattern item. Added the /C option to
1513        pcretest to make use of this.
1515     4. On the advice of a Windows user, the lines
1517          #if defined(_WIN32) || defined(WIN32)
1518          _setmode( _fileno( stdout ), 0x8000 );
1519          #endif  /* defined(_WIN32) || defined(WIN32) */
1521        have been added to the source of pcretest. This apparently does useful
1522        magic in relation to line terminators.
1524     5. Changed "r" and "w" in the calls to fopen() in pcretest to "rb" and "wb"
1525        for the benefit of those environments where the "b" makes a difference.
1527     6. The icc compiler has the same options as gcc, but "configure" doesn't seem
1528        to know about it. I have put a hack into configure.in that adds in code
1529        to set GCC=yes if CC=icc. This seems to end up at a point in the
1530        generated configure script that is early enough to affect the setting of
1531        compiler options, which is what is needed, but I have no means of testing
1532        whether it really works. (The user who reported this had patched the
1533        generated configure script, which of course I cannot do.)
1535        LATER: After change 22 below (new libtool files), the configure script
1536        seems to know about icc (and also ecc). Therefore, I have commented out
1537        this hack in configure.in.
1539     7. Added support for pkg-config (2 patches were sent in).
1541     8. Negated POSIX character classes that used a combination of internal tables
1542        were completely broken. These were [[:^alpha:]], [[:^alnum:]], and
1543        [[:^ascii]]. Typically, they would match almost any characters. The other
1544        POSIX classes were not broken in this way.
1546     9. Matching the pattern "\b.*?" against "ab cd", starting at offset 1, failed
1547        to find the match, as PCRE was deluded into thinking that the match had to
1548        start at the start point or following a newline. The same bug applied to
1549        patterns with negative forward assertions or any backward assertions
1550        preceding ".*" at the start, unless the pattern required a fixed first
1551        character. This was a failing pattern: "(?!.bcd).*". The bug is now fixed.
1553    10. In UTF-8 mode, when moving forwards in the subject after a failed match
1554        starting at the last subject character, bytes beyond the end of the subject
1555        string were read.
1557    11. Renamed the variable "class" as "classbits" to make life easier for C++
1558        users. (Previously there was a macro definition, but it apparently wasn't
1559        enough.)
1561    12. Added the new field "tables" to the extra data so that tables can be passed
1562        in at exec time, or the internal tables can be re-selected. This allows
1563        a compiled regex to be saved and re-used at a later time by a different
1564        program that might have everything at different addresses.
1566    13. Modified the pcre-config script so that, when run on Solaris, it shows a
1567        -R library as well as a -L library.
1569    14. The debugging options of pcretest (-d on the command line or D on a
1570        pattern) showed incorrect output for anything following an extended class
1571        that contained multibyte characters and which was followed by a quantifier.
1573    15. Added optional support for general category Unicode character properties
1574        via the \p, \P, and \X escapes. Unicode property support implies UTF-8
1575        support. It adds about 90K to the size of the library. The meanings of the
1576        inbuilt class escapes such as \d and \s have NOT been changed.
1578    16. Updated pcredemo.c to include calls to free() to release the memory for the
1579        compiled pattern.
1581    17. The generated file chartables.c was being created in the source directory
1582        instead of in the building directory. This caused the build to fail if the
1583        source directory was different from the building directory, and was
1584        read-only.
1586    18. Added some sample Win commands from Mark Tetrode into the NON-UNIX-USE
1587        file. No doubt somebody will tell me if they don't make sense... Also added
1588        Dan Mooney's comments about building on OpenVMS.
1590    19. Added support for partial matching via the PCRE_PARTIAL option for
1591        pcre_exec() and the \P data escape in pcretest.
1593    20. Extended pcretest with 3 new pattern features:
1595        (i)   A pattern option of the form ">rest-of-line" causes pcretest to
1596              write the compiled pattern to the file whose name is "rest-of-line".
1597              This is a straight binary dump of the data, with the saved pointer to
1598              the character tables forced to be NULL. The study data, if any, is
1599              written too. After writing, pcretest reads a new pattern.
1601        (ii)  If, instead of a pattern, "<rest-of-line" is given, pcretest reads a
1602              compiled pattern from the given file. There must not be any
1603              occurrences of "<" in the file name (pretty unlikely); if there are,
1604              pcretest will instead treat the initial "<" as a pattern delimiter.
1605              After reading in the pattern, pcretest goes on to read data lines as
1606              usual.
1608        (iii) The F pattern option causes pcretest to flip the bytes in the 32-bit
1609              and 16-bit fields in a compiled pattern, to simulate a pattern that
1610              was compiled on a host of opposite endianness.
1612    21. The pcre-exec() function can now cope with patterns that were compiled on
1613        hosts of opposite endianness, with this restriction:
1615          As for any compiled expression that is saved and used later, the tables
1616          pointer field cannot be preserved; the extra_data field in the arguments
1617          to pcre_exec() should be used to pass in a tables address if a value
1618          other than the default internal tables were used at compile time.
1620    22. Calling pcre_exec() with a negative value of the "ovecsize" parameter is
1621        now diagnosed as an error. Previously, most of the time, a negative number
1622        would have been treated as zero, but if in addition "ovector" was passed as
1623        NULL, a crash could occur.
1625    23. Updated the files ltmain.sh, config.sub, config.guess, and aclocal.m4 with
1626        new versions from the libtool 1.5 distribution (the last one is a copy of
1627        a file called libtool.m4). This seems to have fixed the need to patch
1628        "configure" to support Darwin 1.3 (which I used to do). However, I still
1629        had to patch ltmain.sh to ensure that ${SED} is set (it isn't on my
1630        workstation).
1632    24. Changed the PCRE licence to be the more standard "BSD" licence.
1635    Version 4.5 01-Dec-03
1636    ---------------------
1638     1. There has been some re-arrangement of the code for the match() function so
1639        that it can be compiled in a version that does not call itself recursively.
1640        Instead, it keeps those local variables that need separate instances for
1641        each "recursion" in a frame on the heap, and gets/frees frames whenever it
1642        needs to "recurse". Keeping track of where control must go is done by means
1643        of setjmp/longjmp. The whole thing is implemented by a set of macros that
1644        hide most of the details from the main code, and operates only if
1645        NO_RECURSE is defined while compiling pcre.c. If PCRE is built using the
1646        "configure" mechanism, "--disable-stack-for-recursion" turns on this way of
1647        operating.
1649        To make it easier for callers to provide specially tailored get/free
1650        functions for this usage, two new functions, pcre_stack_malloc, and
1651        pcre_stack_free, are used. They are always called in strict stacking order,
1652        and the size of block requested is always the same.
1654        The PCRE_CONFIG_STACKRECURSE info parameter can be used to find out whether
1655        PCRE has been compiled to use the stack or the heap for recursion. The
1656        -C option of pcretest uses this to show which version is compiled.
1658        A new data escape \S, is added to pcretest; it causes the amounts of store
1659        obtained and freed by both kinds of malloc/free at match time to be added
1660        to the output.
1662     2. Changed the locale test to use "fr_FR" instead of "fr" because that's
1663        what's available on my current Linux desktop machine.
1665     3. When matching a UTF-8 string, the test for a valid string at the start has
1666        been extended. If start_offset is not zero, PCRE now checks that it points
1667        to a byte that is the start of a UTF-8 character. If not, it returns
1668        PCRE_ERROR_BADUTF8_OFFSET (-11). Note: the whole string is still checked;
1669        this is necessary because there may be backward assertions in the pattern.
1670        When matching the same subject several times, it may save resources to use
1671        PCRE_NO_UTF8_CHECK on all but the first call if the string is long.
1673     4. The code for checking the validity of UTF-8 strings has been tightened so
1674        that it rejects (a) strings containing 0xfe or 0xff bytes and (b) strings
1675        containing "overlong sequences".
1677     5. Fixed a bug (appearing twice) that I could not find any way of exploiting!
1678        I had written "if ((digitab[*p++] && chtab_digit) == 0)" where the "&&"
1679        should have been "&", but it just so happened that all the cases this let
1680        through by mistake were picked up later in the function.
1682     6. I had used a variable called "isblank" - this is a C99 function, causing
1683        some compilers to warn. To avoid this, I renamed it (as "blankclass").
1685     7. Cosmetic: (a) only output another newline at the end of pcretest if it is
1686        prompting; (b) run "./pcretest /dev/null" at the start of the test script
1687        so the version is shown; (c) stop "make test" echoing "./RunTest".
1689     8. Added patches from David Burgess to enable PCRE to run on EBCDIC systems.
1691     9. The prototype for memmove() for systems that don't have it was using
1692        size_t, but the inclusion of the header that defines size_t was later. I've
1693        moved the #includes for the C headers earlier to avoid this.
1695    10. Added some adjustments to the code to make it easier to compiler on certain
1696        special systems:
1698          (a) Some "const" qualifiers were missing.
1699          (b) Added the macro EXPORT before all exported functions; by default this
1700              is defined to be empty.
1701          (c) Changed the dftables auxiliary program (that builds chartables.c) so
1702              that it reads its output file name as an argument instead of writing
1703              to the standard output and assuming this can be redirected.
1705    11. In UTF-8 mode, if a recursive reference (e.g. (?1)) followed a character
1706        class containing characters with values greater than 255, PCRE compilation
1707        went into a loop.
1709    12. A recursive reference to a subpattern that was within another subpattern
1710        that had a minimum quantifier of zero caused PCRE to crash. For example,
1711        (x(y(?2))z)? provoked this bug with a subject that got as far as the
1712        recursion. If the recursively-called subpattern itself had a zero repeat,
1713        that was OK.
1715    13. In pcretest, the buffer for reading a data line was set at 30K, but the
1716        buffer into which it was copied (for escape processing) was still set at
1717        1024, so long lines caused crashes.
1719    14. A pattern such as /[ab]{1,3}+/ failed to compile, giving the error
1720        "internal error: code overflow...". This applied to any character class
1721        that was followed by a possessive quantifier.
1723    15. Modified the Makefile to add libpcre.la as a prerequisite for
1724        libpcreposix.la because I was told this is needed for a parallel build to
1725        work.
1727    16. If a pattern that contained .* following optional items at the start was
1728        studied, the wrong optimizing data was generated, leading to matching
1729        errors. For example, studying /[ab]*.*c/ concluded, erroneously, that any
1730        matching string must start with a or b or c. The correct conclusion for
1731        this pattern is that a match can start with any character.
1734    Version 4.4 13-Aug-03
1735    ---------------------
1737     1. In UTF-8 mode, a character class containing characters with values between
1738        127 and 255 was not handled correctly if the compiled pattern was studied.
1739        In fixing this, I have also improved the studying algorithm for such
1740        classes (slightly).
1742     2. Three internal functions had redundant arguments passed to them. Removal
1743        might give a very teeny performance improvement.
1745     3. Documentation bug: the value of the capture_top field in a callout is *one
1746        more than* the number of the hightest numbered captured substring.
1748     4. The Makefile linked pcretest and pcregrep with -lpcre, which could result
1749        in incorrectly linking with a previously installed version. They now link
1750        explicitly with libpcre.la.
1752     5. configure.in no longer needs to recognize Cygwin specially.
1754     6. A problem in pcre.in for Windows platforms is fixed.
1756     7. If a pattern was successfully studied, and the -d (or /D) flag was given to
1757        pcretest, it used to include the size of the study block as part of its
1758        output. Unfortunately, the structure contains a field that has a different
1759        size on different hardware architectures. This meant that the tests that
1760        showed this size failed. As the block is currently always of a fixed size,
1761        this information isn't actually particularly useful in pcretest output, so
1762        I have just removed it.
1764     8. Three pre-processor statements accidentally did not start in column 1.
1765        Sadly, there are *still* compilers around that complain, even though
1766        standard C has not required this for well over a decade. Sigh.
1768     9. In pcretest, the code for checking callouts passed small integers in the
1769        callout_data field, which is a void * field. However, some picky compilers
1770        complained about the casts involved for this on 64-bit systems. Now
1771        pcretest passes the address of the small integer instead, which should get
1772        rid of the warnings.
1774    10. By default, when in UTF-8 mode, PCRE now checks for valid UTF-8 strings at
1775        both compile and run time, and gives an error if an invalid UTF-8 sequence
1776        is found. There is a option for disabling this check in cases where the
1777        string is known to be correct and/or the maximum performance is wanted.
1779    11. In response to a bug report, I changed one line in Makefile.in from
1781            -Wl,--out-implib,.libs/lib@WIN_PREFIX@pcreposix.dll.a \
1782        to
1783            -Wl,--out-implib,.libs/@WIN_PREFIX@libpcreposix.dll.a \
1785        to look similar to other lines, but I have no way of telling whether this
1786        is the right thing to do, as I do not use Windows. No doubt I'll get told
1787        if it's wrong...
1790    Version 4.3 21-May-03
1791    ---------------------
1793    1. Two instances of @WIN_PREFIX@ omitted from the Windows targets in the
1794       Makefile.
1796    2. Some refactoring to improve the quality of the code:
1798       (i)   The utf8_table... variables are now declared "const".
1800       (ii)  The code for \cx, which used the "case flipping" table to upper case
1801             lower case letters, now just substracts 32. This is ASCII-specific,
1802             but the whole concept of \cx is ASCII-specific, so it seems
1803             reasonable.
1805       (iii) PCRE was using its character types table to recognize decimal and
1806             hexadecimal digits in the pattern. This is silly, because it handles
1807             only 0-9, a-f, and A-F, but the character types table is locale-
1808             specific, which means strange things might happen. A private
1809             table is now used for this - though it costs 256 bytes, a table is
1810             much faster than multiple explicit tests. Of course, the standard
1811             character types table is still used for matching digits in subject
1812             strings against \d.
1814       (iv)  Strictly, the identifier ESC_t is reserved by POSIX (all identifiers
1815             ending in _t are). So I've renamed it as ESC_tee.
1817    3. The first argument for regexec() in the POSIX wrapper should have been
1818       defined as "const".
1820    4. Changed pcretest to use malloc() for its buffers so that they can be
1821       Electric Fenced for debugging.
1823    5. There were several places in the code where, in UTF-8 mode, PCRE would try
1824       to read one or more bytes before the start of the subject string. Often this
1825       had no effect on PCRE's behaviour, but in some circumstances it could
1826       provoke a segmentation fault.
1828    6. A lookbehind at the start of a pattern in UTF-8 mode could also cause PCRE
1829       to try to read one or more bytes before the start of the subject string.
1831    7. A lookbehind in a pattern matched in non-UTF-8 mode on a PCRE compiled with
1832       UTF-8 support could misbehave in various ways if the subject string
1833       contained bytes with the 0x80 bit set and the 0x40 bit unset in a lookbehind
1834       area. (PCRE was not checking for the UTF-8 mode flag, and trying to move
1835       back over UTF-8 characters.)
1838    Version 4.2 14-Apr-03
1839    ---------------------
1841    1. Typo "#if SUPPORT_UTF8" instead of "#ifdef SUPPORT_UTF8" fixed.
1843    2. Changes to the building process, supplied by Ronald Landheer-Cieslak
1844         [ON_WINDOWS]: new variable, "#" on non-Windows platforms
1845         [NOT_ON_WINDOWS]: new variable, "#" on Windows platforms
1846         [WIN_PREFIX]: new variable, "cyg" for Cygwin
1847         * Makefile.in: use autoconf substitution for OBJEXT, EXEEXT, BUILD_OBJEXT
1848           and BUILD_EXEEXT
1849         Note: automatic setting of the BUILD variables is not yet working
1850         set CPPFLAGS and BUILD_CPPFLAGS (but don't use yet) - should be used at
1851           compile-time but not at link-time
1852         [LINK]: use for linking executables only
1853         make different versions for Windows and non-Windows
1854         [LINKLIB]: new variable, copy of UNIX-style LINK, used for linking
1855           libraries
1856         [LINK_FOR_BUILD]: new variable
1857         [OBJEXT]: use throughout
1858         [EXEEXT]: use throughout
1859         <winshared>: new target
1860         <wininstall>: new target
1861         <dftables.o>: use native compiler
1862         <dftables>: use native linker
1863         <install>: handle Windows platform correctly
1864         <clean>: ditto
1865         <check>: ditto
1866         copy DLL to top builddir before testing
1868       As part of these changes, -no-undefined was removed again. This was reported
1869       to give trouble on HP-UX 11.0, so getting rid of it seems like a good idea
1870       in any case.
1872    3. Some tidies to get rid of compiler warnings:
1874       . In the match_data structure, match_limit was an unsigned long int, whereas
1875         match_call_count was an int. I've made them both unsigned long ints.
1877       . In pcretest the fact that a const uschar * doesn't automatically cast to
1878         a void * provoked a warning.
1880       . Turning on some more compiler warnings threw up some "shadow" variables
1881         and a few more missing casts.
1883    4. If PCRE was complied with UTF-8 support, but called without the PCRE_UTF8
1884       option, a class that contained a single character with a value between 128
1885       and 255 (e.g. /[\xFF]/) caused PCRE to crash.
1887    5. If PCRE was compiled with UTF-8 support, but called without the PCRE_UTF8
1888       option, a class that contained several characters, but with at least one
1889       whose value was between 128 and 255 caused PCRE to crash.
1892    Version 4.1 12-Mar-03
1893    ---------------------
1895    1. Compiling with gcc -pedantic found a couple of places where casts were
1896    needed, and a string in dftables.c that was longer than standard compilers are
1897    required to support.
1899    2. Compiling with Sun's compiler found a few more places where the code could
1900    be tidied up in order to avoid warnings.
1902    3. The variables for cross-compiling were called HOST_CC and HOST_CFLAGS; the
1903    first of these names is deprecated in the latest Autoconf in favour of the name
1904    CC_FOR_BUILD, because "host" is typically used to mean the system on which the
1905    compiled code will be run. I can't find a reference for HOST_CFLAGS, but by
1906    analogy I have changed it to CFLAGS_FOR_BUILD.
1908    4. Added -no-undefined to the linking command in the Makefile, because this is
1909    apparently helpful for Windows. To make it work, also added "-L. -lpcre" to the
1910    linking step for the pcreposix library.
1912    5. PCRE was failing to diagnose the case of two named groups with the same
1913    name.
1915    6. A problem with one of PCRE's optimizations was discovered. PCRE remembers a
1916    literal character that is needed in the subject for a match, and scans along to
1917    ensure that it is present before embarking on the full matching process. This
1918    saves time in cases of nested unlimited repeats that are never going to match.
1919    Problem: the scan can take a lot of time if the subject is very long (e.g.
1920    megabytes), thus penalizing straightforward matches. It is now done only if the
1921    amount of subject to be scanned is less than 1000 bytes.
1923    7. A lesser problem with the same optimization is that it was recording the
1924    first character of an anchored pattern as "needed", thus provoking a search
1925    right along the subject, even when the first match of the pattern was going to
1926    fail. The "needed" character is now not set for anchored patterns, unless it
1927    follows something in the pattern that is of non-fixed length. Thus, it still
1928    fulfils its original purpose of finding quick non-matches in cases of nested
1929    unlimited repeats, but isn't used for simple anchored patterns such as /^abc/.
1932    Version 4.0 17-Feb-03
1933    ---------------------
1935    1. If a comment in an extended regex that started immediately after a meta-item
1936    extended to the end of string, PCRE compiled incorrect data. This could lead to
1937    all kinds of weird effects. Example: /#/ was bad; /()#/ was bad; /a#/ was not.
1939    2. Moved to autoconf 2.53 and libtool 1.4.2.
1941    3. Perl 5.8 no longer needs "use utf8" for doing UTF-8 things. Consequently,
1942    the special perltest8 script is no longer needed - all the tests can be run
1943    from a single perltest script.
1945    4. From 5.004, Perl has not included the VT character (0x0b) in the set defined
1946    by \s. It has now been removed in PCRE. This means it isn't recognized as
1947    whitespace in /x regexes too, which is the same as Perl. Note that the POSIX
1948    class [:space:] *does* include VT, thereby creating a mess.
1950    5. Added the class [:blank:] (a GNU extension from Perl 5.8) to match only
1951    space and tab.
1953    6. Perl 5.005 was a long time ago. It's time to amalgamate the tests that use
1954    its new features into the main test script, reducing the number of scripts.
1956    7. Perl 5.8 has changed the meaning of patterns like /a(?i)b/. Earlier versions
1957    were backward compatible, and made the (?i) apply to the whole pattern, as if
1958    /i were given. Now it behaves more logically, and applies the option setting
1959    only to what follows. PCRE has been changed to follow suit. However, if it
1960    finds options settings right at the start of the pattern, it extracts them into
1961    the global options, as before. Thus, they show up in the info data.
1963    8. Added support for the \Q...\E escape sequence. Characters in between are
1964    treated as literals. This is slightly different from Perl in that $ and @ are
1965    also handled as literals inside the quotes. In Perl, they will cause variable
1966    interpolation. Note the following examples:
1968        Pattern            PCRE matches      Perl matches
1970        \Qabc$xyz\E        abc$xyz           abc followed by the contents of $xyz
1971        \Qabc\$xyz\E       abc\$xyz          abc\$xyz
1972        \Qabc\E\$\Qxyz\E   abc$xyz           abc$xyz
1974    For compatibility with Perl, \Q...\E sequences are recognized inside character
1975    classes as well as outside them.
1977    9. Re-organized 3 code statements in pcretest to avoid "overflow in
1978    floating-point constant arithmetic" warnings from a Microsoft compiler. Added a
1979    (size_t) cast to one statement in pcretest and one in pcreposix to avoid
1980    signed/unsigned warnings.
1982    10. SunOS4 doesn't have strtoul(). This was used only for unpicking the -o
1983    option for pcretest, so I've replaced it by a simple function that does just
1984    that job.
1986    11. pcregrep was ending with code 0 instead of 2 for the commands "pcregrep" or
1987    "pcregrep -".
1989    12. Added "possessive quantifiers" ?+, *+, ++, and {,}+ which come from Sun's
1990    Java package. This provides some syntactic sugar for simple cases of what my
1991    documentation calls "once-only subpatterns". A pattern such as x*+ is the same
1992    as (?>x*). In other words, if what is inside (?>...) is just a single repeated
1993    item, you can use this simplified notation. Note that only makes sense with
1994    greedy quantifiers. Consequently, the use of the possessive quantifier forces
1995    greediness, whatever the setting of the PCRE_UNGREEDY option.
1997    13. A change of greediness default within a pattern was not taking effect at
1998    the current level for patterns like /(b+(?U)a+)/. It did apply to parenthesized
1999    subpatterns that followed. Patterns like /b+(?U)a+/ worked because the option
2000    was abstracted outside.
2002    14. PCRE now supports the \G assertion. It is true when the current matching
2003    position is at the start point of the match. This differs from \A when the
2004    starting offset is non-zero. Used with the /g option of pcretest (or similar
2005    code), it works in the same way as it does for Perl's /g option. If all
2006    alternatives of a regex begin with \G, the expression is anchored to the start
2007    match position, and the "anchored" flag is set in the compiled expression.
2009    15. Some bugs concerning the handling of certain option changes within patterns
2010    have been fixed. These applied to options other than (?ims). For example,
2011    "a(?x: b c )d" did not match "XabcdY" but did match "Xa b c dY". It should have
2012    been the other way round. Some of this was related to change 7 above.
2014    16. PCRE now gives errors for /[.x.]/ and /[=x=]/ as unsupported POSIX
2015    features, as Perl does. Previously, PCRE gave the warnings only for /[[.x.]]/
2016    and /[[=x=]]/. PCRE now also gives an error for /[:name:]/ because it supports
2017    POSIX classes only within a class (e.g. /[[:alpha:]]/).
2019    17. Added support for Perl's \C escape. This matches one byte, even in UTF8
2020    mode. Unlike ".", it always matches newline, whatever the setting of
2021    PCRE_DOTALL. However, PCRE does not permit \C to appear in lookbehind
2022    assertions. Perl allows it, but it doesn't (in general) work because it can't
2023    calculate the length of the lookbehind. At least, that's the case for Perl
2024    5.8.0 - I've been told they are going to document that it doesn't work in
2025    future.
2027    18. Added an error diagnosis for escapes that PCRE does not support: these are
2028    \L, \l, \N, \P, \p, \U, \u, and \X.
2030    19. Although correctly diagnosing a missing ']' in a character class, PCRE was
2031    reading past the end of the pattern in cases such as /[abcd/.
2033    20. PCRE was getting more memory than necessary for patterns with classes that
2034    contained both POSIX named classes and other characters, e.g. /[[:space:]abc/.
2036    21. Added some code, conditional on #ifdef VPCOMPAT, to make life easier for
2037    compiling PCRE for use with Virtual Pascal.
2039    22. Small fix to the Makefile to make it work properly if the build is done
2040    outside the source tree.
2042    23. Added a new extension: a condition to go with recursion. If a conditional
2043    subpattern starts with (?(R) the "true" branch is used if recursion has
2044    happened, whereas the "false" branch is used only at the top level.
2046    24. When there was a very long string of literal characters (over 255 bytes
2047    without UTF support, over 250 bytes with UTF support), the computation of how
2048    much memory was required could be incorrect, leading to segfaults or other
2049    strange effects.
2051    25. PCRE was incorrectly assuming anchoring (either to start of subject or to
2052    start of line for a non-DOTALL pattern) when a pattern started with (.*) and
2053    there was a subsequent back reference to those brackets. This meant that, for
2054    example, /(.*)\d+\1/ failed to match "abc123bc". Unfortunately, it isn't
2055    possible to check for precisely this case. All we can do is abandon the
2056    optimization if .* occurs inside capturing brackets when there are any back
2057    references whatsoever. (See below for a better fix that came later.)
2059    26. The handling of the optimization for finding the first character of a
2060    non-anchored pattern, and for finding a character that is required later in the
2061    match were failing in some cases. This didn't break the matching; it just
2062    failed to optimize when it could. The way this is done has been re-implemented.
2064    27. Fixed typo in error message for invalid (?R item (it said "(?p").
2066    28. Added a new feature that provides some of the functionality that Perl
2067    provides with (?{...}). The facility is termed a "callout". The way it is done
2068    in PCRE is for the caller to provide an optional function, by setting
2069    pcre_callout to its entry point. Like pcre_malloc and pcre_free, this is a
2070    global variable. By default it is unset, which disables all calling out. To get
2071    the function called, the regex must include (?C) at appropriate points. This
2072    is, in fact, equivalent to (?C0), and any number <= 255 may be given with (?C).
2073    This provides a means of identifying different callout points. When PCRE
2074    reaches such a point in the regex, if pcre_callout has been set, the external
2075    function is called. It is provided with data in a structure called
2076    pcre_callout_block, which is defined in pcre.h. If the function returns 0,
2077    matching continues; if it returns a non-zero value, the match at the current
2078    point fails. However, backtracking will occur if possible. [This was changed
2079    later and other features added - see item 49 below.]
2081    29. pcretest is upgraded to test the callout functionality. It provides a
2082    callout function that displays information. By default, it shows the start of
2083    the match and the current position in the text. There are some new data escapes
2084    to vary what happens:
2086        \C+         in addition, show current contents of captured substrings
2087        \C-         do not supply a callout function
2088        \C!n        return 1 when callout number n is reached
2089        \C!n!m      return 1 when callout number n is reached for the mth time
2091    30. If pcregrep was called with the -l option and just a single file name, it
2092    output "<stdin>" if a match was found, instead of the file name.
2094    31. Improve the efficiency of the POSIX API to PCRE. If the number of capturing
2095    slots is less than POSIX_MALLOC_THRESHOLD, use a block on the stack to pass to
2096    pcre_exec(). This saves a malloc/free per call. The default value of
2097    POSIX_MALLOC_THRESHOLD is 10; it can be changed by --with-posix-malloc-threshold
2098    when configuring.
2100    32. The default maximum size of a compiled pattern is 64K. There have been a
2101    few cases of people hitting this limit. The code now uses macros to handle the
2102    storing of links as offsets within the compiled pattern. It defaults to 2-byte
2103    links, but this can be changed to 3 or 4 bytes by --with-link-size when
2104    configuring. Tests 2 and 5 work only with 2-byte links because they output
2105    debugging information about compiled patterns.
2107    33. Internal code re-arrangements:
2109    (a) Moved the debugging function for printing out a compiled regex into
2110        its own source file (printint.c) and used #include to pull it into
2111        pcretest.c and, when DEBUG is defined, into pcre.c, instead of having two
2112        separate copies.
2114    (b) Defined the list of op-code names for debugging as a macro in
2115        internal.h so that it is next to the definition of the opcodes.
2117    (c) Defined a table of op-code lengths for simpler skipping along compiled
2118        code. This is again a macro in internal.h so that it is next to the
2119        definition of the opcodes.
2121    34. Added support for recursive calls to individual subpatterns, along the
2122    lines of Robin Houston's patch (but implemented somewhat differently).
2124    35. Further mods to the Makefile to help Win32. Also, added code to pcregrep to
2125    allow it to read and process whole directories in Win32. This code was
2126    contributed by Lionel Fourquaux; it has not been tested by me.
2128    36. Added support for named subpatterns. The Python syntax (?P<name>...) is
2129    used to name a group. Names consist of alphanumerics and underscores, and must
2130    be unique. Back references use the syntax (?P=name) and recursive calls use
2131    (?P>name) which is a PCRE extension to the Python extension. Groups still have
2132    numbers. The function pcre_fullinfo() can be used after compilation to extract
2133    a name/number map. There are three relevant calls:
2135      PCRE_INFO_NAMEENTRYSIZE        yields the size of each entry in the map
2136      PCRE_INFO_NAMECOUNT            yields the number of entries
2137      PCRE_INFO_NAMETABLE            yields a pointer to the map.
2139    The map is a vector of fixed-size entries. The size of each entry depends on
2140    the length of the longest name used. The first two bytes of each entry are the
2141    group number, most significant byte first. There follows the corresponding
2142    name, zero terminated. The names are in alphabetical order.
2144    37. Make the maximum literal string in the compiled code 250 for the non-UTF-8
2145    case instead of 255. Making it the same both with and without UTF-8 support
2146    means that the same test output works with both.
2148    38. There was a case of malloc(0) in the POSIX testing code in pcretest. Avoid
2149    calling malloc() with a zero argument.
2151    39. Change 25 above had to resort to a heavy-handed test for the .* anchoring
2152    optimization. I've improved things by keeping a bitmap of backreferences with
2153    numbers 1-31 so that if .* occurs inside capturing brackets that are not in
2154    fact referenced, the optimization can be applied. It is unlikely that a
2155    relevant occurrence of .* (i.e. one which might indicate anchoring or forcing
2156    the match to follow \n) will appear inside brackets with a number greater than
2157    31, but if it does, any back reference > 31 suppresses the optimization.
2159    40. Added a new compile-time option PCRE_NO_AUTO_CAPTURE. This has the effect
2160    of disabling numbered capturing parentheses. Any opening parenthesis that is
2161    not followed by ? behaves as if it were followed by ?: but named parentheses
2162    can still be used for capturing (and they will acquire numbers in the usual
2163    way).
2165    41. Redesigned the return codes from the match() function into yes/no/error so
2166    that errors can be passed back from deep inside the nested calls. A malloc
2167    failure while inside a recursive subpattern call now causes the
2168    PCRE_ERROR_NOMEMORY return instead of quietly going wrong.
2170    42. It is now possible to set a limit on the number of times the match()
2171    function is called in a call to pcre_exec(). This facility makes it possible to
2172    limit the amount of recursion and backtracking, though not in a directly
2173    obvious way, because the match() function is used in a number of different
2174    circumstances. The count starts from zero for each position in the subject
2175    string (for non-anchored patterns). The default limit is, for compatibility, a
2176    large number, namely 10 000 000. You can change this in two ways:
2178    (a) When configuring PCRE before making, you can use --with-match-limit=n
2179        to set a default value for the compiled library.
2181    (b) For each call to pcre_exec(), you can pass a pcre_extra block in which
2182        a different value is set. See 45 below.
2184    If the limit is exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT.
2186    43. Added a new function pcre_config(int, void *) to enable run-time extraction
2187    of things that can be changed at compile time. The first argument specifies
2188    what is wanted and the second points to where the information is to be placed.
2189    The current list of available information is:
2191      PCRE_CONFIG_UTF8
2193    The output is an integer that is set to one if UTF-8 support is available;
2194    otherwise it is set to zero.
2198    The output is an integer that it set to the value of the code that is used for
2199    newline. It is either LF (10) or CR (13).
2203    The output is an integer that contains the number of bytes used for internal
2204    linkage in compiled expressions. The value is 2, 3, or 4. See item 32 above.
2208    The output is an integer that contains the threshold above which the POSIX
2209    interface uses malloc() for output vectors. See item 31 above.
2213    The output is an unsigned integer that contains the default limit of the number
2214    of match() calls in a pcre_exec() execution. See 42 above.
2216    44. pcretest has been upgraded by the addition of the -C option. This causes it
2217    to extract all the available output from the new pcre_config() function, and to
2218    output it. The program then exits immediately.
2220    45. A need has arisen to pass over additional data with calls to pcre_exec() in
2221    order to support additional features. One way would have been to define
2222    pcre_exec2() (for example) with extra arguments, but this would not have been
2223    extensible, and would also have required all calls to the original function to
2224    be mapped to the new one. Instead, I have chosen to extend the mechanism that
2225    is used for passing in "extra" data from pcre_study().
2227    The pcre_extra structure is now exposed and defined in pcre.h. It currently
2228    contains the following fields:
2230      flags         a bitmap indicating which of the following fields are set
2231      study_data    opaque data from pcre_study()
2232      match_limit   a way of specifying a limit on match() calls for a specific
2233                      call to pcre_exec()
2234      callout_data  data for callouts (see 49 below)
2236    The flag bits are also defined in pcre.h, and are
2242    The pcre_study() function now returns one of these new pcre_extra blocks, with
2243    the actual study data pointed to by the study_data field, and the
2244    PCRE_EXTRA_STUDY_DATA flag set. This can be passed directly to pcre_exec() as
2245    before. That is, this change is entirely upwards-compatible and requires no
2246    change to existing code.
2248    If you want to pass in additional data to pcre_exec(), you can either place it
2249    in a pcre_extra block provided by pcre_study(), or create your own pcre_extra
2250    block.
2252    46. pcretest has been extended to test the PCRE_EXTRA_MATCH_LIMIT feature. If a
2253    data string contains the escape sequence \M, pcretest calls pcre_exec() several
2254    times with different match limits, until it finds the minimum value needed for
2255    pcre_exec() to complete. The value is then output. This can be instructive; for
2256    most simple matches the number is quite small, but for pathological cases it
2257    gets very large very quickly.
2259    47. There's a new option for pcre_fullinfo() called PCRE_INFO_STUDYSIZE. It
2260    returns the size of the data block pointed to by the study_data field in a
2261    pcre_extra block, that is, the value that was passed as the argument to
2262    pcre_malloc() when PCRE was getting memory in which to place the information
2263    created by pcre_study(). The fourth argument should point to a size_t variable.
2264    pcretest has been extended so that this information is shown after a successful
2265    pcre_study() call when information about the compiled regex is being displayed.
2267    48. Cosmetic change to Makefile: there's no need to have / after $(DESTDIR)
2268    because what follows is always an absolute path. (Later: it turns out that this
2269    is more than cosmetic for MinGW, because it doesn't like empty path
2270    components.)
2272    49. Some changes have been made to the callout feature (see 28 above):
2274    (i)  A callout function now has three choices for what it returns:
2276           0  =>  success, carry on matching
2277         > 0  =>  failure at this point, but backtrack if possible
2278         < 0  =>  serious error, return this value from pcre_exec()
2280         Negative values should normally be chosen from the set of PCRE_ERROR_xxx
2281         values. In particular, returning PCRE_ERROR_NOMATCH forces a standard
2282         "match failed" error. The error number PCRE_ERROR_CALLOUT is reserved for
2283         use by callout functions. It will never be used by PCRE itself.
2285    (ii) The pcre_extra structure (see 45 above) has a void * field called
2286         callout_data, with corresponding flag bit PCRE_EXTRA_CALLOUT_DATA. The
2287         pcre_callout_block structure has a field of the same name. The contents of
2288         the field passed in the pcre_extra structure are passed to the callout
2289         function in the corresponding field in the callout block. This makes it
2290         easier to use the same callout-containing regex from multiple threads. For
2291         testing, the pcretest program has a new data escape
2293           \C*n        pass the number n (may be negative) as callout_data
2295         If the callout function in pcretest receives a non-zero value as
2296         callout_data, it returns that value.
2298    50. Makefile wasn't handling CFLAGS properly when compiling dftables. Also,
2299    there were some redundant $(CFLAGS) in commands that are now specified as
2300    $(LINK), which already includes $(CFLAGS).
2302    51. Extensions to UTF-8 support are listed below. These all apply when (a) PCRE
2303    has been compiled with UTF-8 support *and* pcre_compile() has been compiled
2304    with the PCRE_UTF8 flag. Patterns that are compiled without that flag assume
2305    one-byte characters throughout. Note that case-insensitive matching applies
2306    only to characters whose values are less than 256. PCRE doesn't support the
2307    notion of cases for higher-valued characters.
2309    (i)   A character class whose characters are all within 0-255 is handled as
2310          a bit map, and the map is inverted for negative classes. Previously, a
2311          character > 255 always failed to match such a class; however it should
2312          match if the class was a negative one (e.g. [^ab]). This has been fixed.
2314    (ii)  A negated character class with a single character < 255 is coded as
2315          "not this character" (OP_NOT). This wasn't working properly when the test
2316          character was multibyte, either singly or repeated.
2318    (iii) Repeats of multibyte characters are now handled correctly in UTF-8
2319          mode, for example: \x{100}{2,3}.
2321    (iv)  The character escapes \b, \B, \d, \D, \s, \S, \w, and \W (either
2322          singly or repeated) now correctly test multibyte characters. However,
2323          PCRE doesn't recognize any characters with values greater than 255 as
2324          digits, spaces, or word characters. Such characters always match \D, \S,
2325          and \W, and never match \d, \s, or \w.
2327    (v)   Classes may now contain characters and character ranges with values
2328          greater than 255. For example: [ab\x{100}-\x{400}].
2330    (vi)  pcregrep now has a --utf-8 option (synonym -u) which makes it call
2331          PCRE in UTF-8 mode.
2333    52. The info request value PCRE_INFO_FIRSTCHAR has been renamed
2334    PCRE_INFO_FIRSTBYTE because it is a byte value. However, the old name is
2335    retained for backwards compatibility. (Note that LASTLITERAL is also a byte
2336    value.)
2338    53. The single man page has become too large. I have therefore split it up into
2339    a number of separate man pages. These also give rise to individual HTML pages;
2340    these are now put in a separate directory, and there is an index.html page that
2341    lists them all. Some hyperlinking between the pages has been installed.
2343    54. Added convenience functions for handling named capturing parentheses.
2345    55. Unknown escapes inside character classes (e.g. [\M]) and escapes that
2346    aren't interpreted therein (e.g. [\C]) are literals in Perl. This is now also
2347    true in PCRE, except when the PCRE_EXTENDED option is set, in which case they
2348    are faulted.
2350    56. Introduced HOST_CC and HOST_CFLAGS which can be set in the environment when
2351    calling configure. These values are used when compiling the dftables.c program
2352    which is run to generate the source of the default character tables. They
2353    default to the values of CC and CFLAGS. If you are cross-compiling PCRE,
2354    you will need to set these values.
2356    57. Updated the building process for Windows DLL, as provided by Fred Cox.
2359    Version 3.9 02-Jan-02
2360    ---------------------
2362    1. A bit of extraneous text had somehow crept into the pcregrep documentation.
2364    2. If --disable-static was given, the building process failed when trying to
2365    build pcretest and pcregrep. (For some reason it was using libtool to compile
2366    them, which is not right, as they aren't part of the library.)
2369    Version 3.8 18-Dec-01
2370    ---------------------
2372    1. The experimental UTF-8 code was completely screwed up. It was packing the
2373    bytes in the wrong order. How dumb can you get?
2376    Version 3.7 29-Oct-01
2377    ---------------------
2379    1. In updating pcretest to check change 1 of version 3.6, I screwed up.
2380    This caused pcretest, when used on the test data, to segfault. Unfortunately,
2381    this didn't happen under Solaris 8, where I normally test things.
2383    2. The Makefile had to be changed to make it work on BSD systems, where 'make'
2384    doesn't seem to recognize that ./xxx and xxx are the same file. (This entry
2385    isn't in ChangeLog distributed with 3.7 because I forgot when I hastily made
2386    this fix an hour or so after the initial 3.7 release.)
2389    Version 3.6 23-Oct-01
2390    ---------------------
2392    1. Crashed with /(sens|respons)e and \1ibility/ and "sense and sensibility" if
2393    offsets passed as NULL with zero offset count.
2395    2. The config.guess and config.sub files had not been updated when I moved to
2396    the latest autoconf.
2399    Version 3.5 15-Aug-01
2400    ---------------------
2402    1. Added some missing #if !defined NOPOSIX conditionals in pcretest.c that
2403    had been forgotten.
2405    2. By using declared but undefined structures, we can avoid using "void"
2406    definitions in pcre.h while keeping the internal definitions of the structures
2407    private.
2409    3. The distribution is now built using autoconf 2.50 and libtool 1.4. From a
2410    user point of view, this means that both static and shared libraries are built
2411    by default, but this can be individually controlled. More of the work of
2412    handling this static/shared cases is now inside libtool instead of PCRE's make
2413    file.
2415    4. The pcretest utility is now installed along with pcregrep because it is
2416    useful for users (to test regexs) and by doing this, it automatically gets
2417    relinked by libtool. The documentation has been turned into a man page, so
2418    there are now .1, .txt, and .html versions in /doc.
2420    5. Upgrades to pcregrep:
2421       (i)   Added long-form option names like gnu grep.
2422       (ii)  Added --help to list all options with an explanatory phrase.
2423       (iii) Added -r, --recursive to recurse into sub-directories.
2424       (iv)  Added -f, --file to read patterns from a file.
2426    6. pcre_exec() was referring to its "code" argument before testing that
2427    argument for NULL (and giving an error if it was NULL).
2429    7. Upgraded Makefile.in to allow for compiling in a different directory from
2430    the source directory.
2432    8. Tiny buglet in pcretest: when pcre_fullinfo() was called to retrieve the
2433    options bits, the pointer it was passed was to an int instead of to an unsigned
2434    long int. This mattered only on 64-bit systems.
2436    9. Fixed typo (3.4/1) in pcre.h again. Sigh. I had changed pcre.h (which is
2437    generated) instead of pcre.in, which it its source. Also made the same change
2438    in several of the .c files.
2440    10. A new release of gcc defines printf() as a macro, which broke pcretest
2441    because it had an ifdef in the middle of a string argument for printf(). Fixed
2442    by using separate calls to printf().
2444    11. Added --enable-newline-is-cr and --enable-newline-is-lf to the configure
2445    script, to force use of CR or LF instead of \n in the source. On non-Unix
2446    systems, the value can be set in config.h.
2448    12. The limit of 200 on non-capturing parentheses is a _nesting_ limit, not an
2449    absolute limit. Changed the text of the error message to make this clear, and
2450    likewise updated the man page.
2452    13. The limit of 99 on the number of capturing subpatterns has been removed.
2453    The new limit is 65535, which I hope will not be a "real" limit.
2456    Version 3.4 22-Aug-00
2457    ---------------------
2459    1. Fixed typo in pcre.h: unsigned const char * changed to const unsigned char *.
2461    2. Diagnose condition (?(0) as an error instead of crashing on matching.
2464    Version 3.3 01-Aug-00
2465    ---------------------
2467    1. If an octal character was given, but the value was greater than \377, it
2468    was not getting masked to the least significant bits, as documented. This could
2469    lead to crashes in some systems.
2471    2. Perl 5.6 (if not earlier versions) accepts classes like [a-\d] and treats
2472    the hyphen as a literal. PCRE used to give an error; it now behaves like Perl.
2474    3. Added the functions pcre_free_substring() and pcre_free_substring_list().
2475    These just pass their arguments on to (pcre_free)(), but they are provided
2476    because some uses of PCRE bind it to non-C systems that can call its functions,
2477    but cannot call free() or pcre_free() directly.
2479    4. Add "make test" as a synonym for "make check". Corrected some comments in
2480    the Makefile.
2482    5. Add $(DESTDIR)/ in front of all the paths in the "install" target in the
2483    Makefile.
2485    6. Changed the name of pgrep to pcregrep, because Solaris has introduced a
2486    command called pgrep for grepping around the active processes.
2488    7. Added the beginnings of support for UTF-8 character strings.
2490    8. Arranged for the Makefile to pass over the settings of CC, CFLAGS, and
2491    RANLIB to ./ltconfig so that they are used by libtool. I think these are all
2492    the relevant ones. (AR is not passed because ./ltconfig does its own figuring
2493    out for the ar command.)
2496    Version 3.2 12-May-00
2497    ---------------------
2499    This is purely a bug fixing release.
2501    1. If the pattern /((Z)+|A)*/ was matched agained ZABCDEFG it matched Z instead
2502    of ZA. This was just one example of several cases that could provoke this bug,
2503    which was introduced by change 9 of version 2.00. The code for breaking
2504    infinite loops after an iteration that matches an empty string was't working
2505    correctly.
2507    2. The pcretest program was not imitating Perl correctly for the pattern /a*/g
2508    when matched against abbab (for example). After matching an empty string, it
2509    wasn't forcing anchoring when setting PCRE_NOTEMPTY for the next attempt; this
2510    caused it to match further down the string than it should.
2512    3. The code contained an inclusion of sys/types.h. It isn't clear why this
2513    was there because it doesn't seem to be needed, and it causes trouble on some
2514    systems, as it is not a Standard C header. It has been removed.
2516    4. Made 4 silly changes to the source to avoid stupid compiler warnings that
2517    were reported on the Macintosh. The changes were from
2519      while ((c = *(++ptr)) != 0 && c != '\n');
2520    to
2521      while ((c = *(++ptr)) != 0 && c != '\n') ;
2523    Totally extraordinary, but if that's what it takes...
2525    5. PCRE is being used in one environment where neither memmove() nor bcopy() is
2526    available. Added HAVE_BCOPY and an autoconf test for it; if neither
2527    HAVE_MEMMOVE nor HAVE_BCOPY is set, use a built-in emulation function which
2528    assumes the way PCRE uses memmove() (always moving upwards).
2530    6. PCRE is being used in one environment where strchr() is not available. There
2531    was only one use in pcre.c, and writing it out to avoid strchr() probably gives
2532    faster code anyway.
2535    Version 3.1 09-Feb-00
2536    ---------------------
2538    The only change in this release is the fixing of some bugs in Makefile.in for
2539    the "install" target:
2541    (1) It was failing to install pcreposix.h.
2543    (2) It was overwriting the pcre.3 man page with the pcreposix.3 man page.
2546    Version 3.0 01-Feb-00
2547    ---------------------
2549    1. Add support for the /+ modifier to perltest (to output $` like it does in
2550    pcretest).
2552    2. Add support for the /g modifier to perltest.
2554    3. Fix pcretest so that it behaves even more like Perl for /g when the pattern
2555    matches null strings.
2557    4. Fix perltest so that it doesn't do unwanted things when fed an empty
2558    pattern. Perl treats empty patterns specially - it reuses the most recent
2559    pattern, which is not what we want. Replace // by /(?#)/ in order to avoid this
2560    effect.
2562    5. The POSIX interface was broken in that it was just handing over the POSIX
2563    captured string vector to pcre_exec(), but (since release 2.00) PCRE has
2564    required a bigger vector, with some working space on the end. This means that
2565    the POSIX wrapper now has to get and free some memory, and copy the results.
2567    6. Added some simple autoconf support, placing the test data and the
2568    documentation in separate directories, re-organizing some of the
2569    information files, and making it build pcre-config (a GNU standard). Also added
2570    libtool support for building PCRE as a shared library, which is now the
2571    default.
2573    7. Got rid of the leading zero in the definition of PCRE_MINOR because 08 and
2574    09 are not valid octal constants. Single digits will be used for minor values
2575    less than 10.
2577    8. Defined REG_EXTENDED and REG_NOSUB as zero in the POSIX header, so that
2578    existing programs that set these in the POSIX interface can use PCRE without
2579    modification.
2581    9. Added a new function, pcre_fullinfo() with an extensible interface. It can
2582    return all that pcre_info() returns, plus additional data. The pcre_info()
2583    function is retained for compatibility, but is considered to be obsolete.
2585    10. Added experimental recursion feature (?R) to handle one common case that
2586    Perl 5.6 will be able to do with (?p{...}).
2588    11. Added support for POSIX character classes like [:alpha:], which Perl is
2589    adopting.
2592    Version 2.08 31-Aug-99
2593    ----------------------
2595    1. When startoffset was not zero and the pattern began with ".*", PCRE was not
2596    trying to match at the startoffset position, but instead was moving forward to
2597    the next newline as if a previous match had failed.
2599    2. pcretest was not making use of PCRE_NOTEMPTY when repeating for /g and /G,
2600    and could get into a loop if a null string was matched other than at the start
2601    of the subject.
2603    3. Added definitions of PCRE_MAJOR and PCRE_MINOR to pcre.h so the version can
2604    be distinguished at compile time, and for completeness also added PCRE_DATE.
2606    5. Added Paul Sokolovsky's minor changes to make it easy to compile a Win32 DLL
2607    in GnuWin32 environments.
2610    Version 2.07 29-Jul-99
2611    ----------------------
2613    1. The documentation is now supplied in plain text form and HTML as well as in
2614    the form of man page sources.
2616    2. C++ compilers don't like assigning (void *) values to other pointer types.
2617    In particular this affects malloc(). Although there is no problem in Standard
2618    C, I've put in casts to keep C++ compilers happy.
2620    3. Typo on pcretest.c; a cast of (unsigned char *) in the POSIX regexec() call
2621    should be (const char *).
2623    4. If NOPOSIX is defined, pcretest.c compiles without POSIX support. This may
2624    be useful for non-Unix systems who don't want to bother with the POSIX stuff.
2625    However, I haven't made this a standard facility. The documentation doesn't
2626    mention it, and the Makefile doesn't support it.
2628    5. The Makefile now contains an "install" target, with editable destinations at
2629    the top of the file. The pcretest program is not installed.
2631    6. pgrep -V now gives the PCRE version number and date.
2633    7. Fixed bug: a zero repetition after a literal string (e.g. /abcde{0}/) was
2634    causing the entire string to be ignored, instead of just the last character.
2636    8. If a pattern like /"([^\\"]+|\\.)*"/ is applied in the normal way to a
2637    non-matching string, it can take a very, very long time, even for strings of
2638    quite modest length, because of the nested recursion. PCRE now does better in
2639    some of these cases. It does this by remembering the last required literal
2640    character in the pattern, and pre-searching the subject to ensure it is present
2641    before running the real match. In other words, it applies a heuristic to detect
2642    some types of certain failure quickly, and in the above example, if presented
2643    with a string that has no trailing " it gives "no match" very quickly.
2645    9. A new runtime option PCRE_NOTEMPTY causes null string matches to be ignored;
2646    other alternatives are tried instead.
2649    Version 2.06 09-Jun-99
2650    ----------------------
2652    1. Change pcretest's output for amount of store used to show just the code
2653    space, because the remainder (the data block) varies in size between 32-bit and
2654    64-bit systems.
2656    2. Added an extra argument to pcre_exec() to supply an offset in the subject to
2657    start matching at. This allows lookbehinds to work when searching for multiple
2658    occurrences in a string.
2660    3. Added additional options to pcretest for testing multiple occurrences:
2662       /+   outputs the rest of the string that follows a match
2663       /g   loops for multiple occurrences, using the new startoffset argument
2664       /G   loops for multiple occurrences by passing an incremented pointer
2666    4. PCRE wasn't doing the "first character" optimization for patterns starting
2667    with \b or \B, though it was doing it for other lookbehind assertions. That is,
2668    it wasn't noticing that a match for a pattern such as /\bxyz/ has to start with
2669    the letter 'x'. On long subject strings, this gives a significant speed-up.
2672    Version 2.05 21-Apr-99
2673    ----------------------
2675    1. Changed the type of magic_number from int to long int so that it works
2676    properly on 16-bit systems.
2678    2. Fixed a bug which caused patterns starting with .* not to work correctly
2679    when the subject string contained newline characters. PCRE was assuming
2680    anchoring for such patterns in all cases, which is not correct because .* will
2681    not pass a newline unless PCRE_DOTALL is set. It now assumes anchoring only if
2682    DOTALL is set at top level; otherwise it knows that patterns starting with .*
2683    must be retried after every newline in the subject.
2686    Version 2.04 18-Feb-99
2687    ----------------------
2689    1. For parenthesized subpatterns with repeats whose minimum was zero, the
2690    computation of the store needed to hold the pattern was incorrect (too large).
2691    If such patterns were nested a few deep, this could multiply and become a real
2692    problem.
2694    2. Added /M option to pcretest to show the memory requirement of a specific
2695    pattern. Made -m a synonym of -s (which does this globally) for compatibility.
2697    3. Subpatterns of the form (regex){n,m} (i.e. limited maximum) were being
2698    compiled in such a way that the backtracking after subsequent failure was
2699    pessimal. Something like (a){0,3} was compiled as (a)?(a)?(a)? instead of
2700    ((a)((a)(a)?)?)? with disastrous performance if the maximum was of any size.
2703    Version 2.03 02-Feb-99
2704    ----------------------
2706    1. Fixed typo and small mistake in man page.
2708    2. Added 4th condition (GPL supersedes if conflict) and created separate
2709    LICENCE file containing the conditions.
2711    3. Updated pcretest so that patterns such as /abc\/def/ work like they do in
2712    Perl, that is the internal \ allows the delimiter to be included in the
2713    pattern. Locked out the use of \ as a delimiter. If \ immediately follows
2714    the final delimiter, add \ to the end of the pattern (to test the error).
2716    4. Added the convenience functions for extracting substrings after a successful
2717    match. Updated pcretest to make it able to test these functions.
2720  Version 2.02 14-Jan-99  Version 2.02 14-Jan-99
2721  ----------------------  ----------------------

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