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revision 51 by nigel, Sat Feb 24 21:39:37 2007 UTC revision 314 by ph10, Fri Jan 25 17:09:21 2008 UTC
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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
4    Version 7.6 21-Jan-08
5    ---------------------
7    1.  A character class containing a very large number of characters with
8        codepoints greater than 255 (in UTF-8 mode, of course) caused a buffer
9        overflow.
11    2.  Patch to cut out the "long long" test in pcrecpp_unittest when
12        HAVE_LONG_LONG is not defined.
14    3.  Applied Christian Ehrlicher's patch to update the CMake build files to
15        bring them up to date and include new features. This patch includes:
17        - Fixed PH's badly added libz and libbz2 support.
18        - Fixed a problem with static linking.
19        - Added pcredemo. [But later removed - see 7 below.]
20        - Fixed dftables problem and added an option.
21        - Added a number of HAVE_XXX tests, including HAVE_WINDOWS_H and
22            HAVE_LONG_LONG.
23        - Added readline support for pcretest.
24        - Added an listing of the option settings after cmake has run.
26    4.  A user submitted a patch to Makefile that makes it easy to create
27        "pcre.dll" under mingw when using Configure/Make. I added stuff to
28        Makefile.am that cause it to include this special target, without
29        affecting anything else. Note that the same mingw target plus all
30        the other distribution libraries and programs are now supported
31        when configuring with CMake (see 6 below) instead of with
32        Configure/Make.
34    5.  Applied Craig's patch that moves no_arg into the RE class in the C++ code.
35        This is an attempt to solve the reported problem "pcrecpp::no_arg is not
36        exported in the Windows port". It has not yet been confirmed that the patch
37        solves the problem, but it does no harm.
39    6.  Applied Sheri's patch to CMakeLists.txt to add NON_STANDARD_LIB_PREFIX and
40        NON_STANDARD_LIB_SUFFIX for dll names built with mingw when configured
41        with CMake, and also correct the comment about stack recursion.
43    7.  Remove the automatic building of pcredemo from the ./configure system and
44        from CMakeLists.txt. The whole idea of pcredemo.c is that it is an example
45        of a program that users should build themselves after PCRE is installed, so
46        building it automatically is not really right. What is more, it gave
47        trouble in some build environments.
50    Version 7.5 10-Jan-08
51    ---------------------
53    1.  Applied a patch from Craig: "This patch makes it possible to 'ignore'
54        values in parens when parsing an RE using the C++ wrapper."
56    2.  Negative specials like \S did not work in character classes in UTF-8 mode.
57        Characters greater than 255 were excluded from the class instead of being
58        included.
60    3.  The same bug as (2) above applied to negated POSIX classes such as
61        [:^space:].
63    4.  PCRECPP_STATIC was referenced in pcrecpp_internal.h, but nowhere was it
64        defined or documented. It seems to have been a typo for PCRE_STATIC, so
65        I have changed it.
67    5.  The construct (?&) was not diagnosed as a syntax error (it referenced the
68        first named subpattern) and a construct such as (?&a) would reference the
69        first named subpattern whose name started with "a" (in other words, the
70        length check was missing). Both these problems are fixed. "Subpattern name
71        expected" is now given for (?&) (a zero-length name), and this patch also
72        makes it give the same error for \k'' (previously it complained that that
73        was a reference to a non-existent subpattern).
75    6.  The erroneous patterns (?+-a) and (?-+a) give different error messages;
76        this is right because (?- can be followed by option settings as well as by
77        digits. I have, however, made the messages clearer.
79    7.  Patterns such as (?(1)a|b) (a pattern that contains fewer subpatterns
80        than the number used in the conditional) now cause a compile-time error.
81        This is actually not compatible with Perl, which accepts such patterns, but
82        treats the conditional as always being FALSE (as PCRE used to), but it
83        seems to me that giving a diagnostic is better.
85    8.  Change "alphameric" to the more common word "alphanumeric" in comments
86        and messages.
88    9.  Fix two occurrences of "backslash" in comments that should have been
89        "backspace".
91    10. Remove two redundant lines of code that can never be obeyed (their function
92        was moved elsewhere).
94    11. The program that makes PCRE's Unicode character property table had a bug
95        which caused it to generate incorrect table entries for sequences of
96        characters that have the same character type, but are in different scripts.
97        It amalgamated them into a single range, with the script of the first of
98        them. In other words, some characters were in the wrong script. There were
99        thirteen such cases, affecting characters in the following ranges:
101          U+002b0 - U+002c1
102          U+0060c - U+0060d
103          U+0061e - U+00612
104          U+0064b - U+0065e
105          U+0074d - U+0076d
106          U+01800 - U+01805
107          U+01d00 - U+01d77
108          U+01d9b - U+01dbf
109          U+0200b - U+0200f
110          U+030fc - U+030fe
111          U+03260 - U+0327f
112          U+0fb46 - U+0fbb1
113          U+10450 - U+1049d
115    12. The -o option (show only the matching part of a line) for pcregrep was not
116        compatible with GNU grep in that, if there was more than one match in a
117        line, it showed only the first of them. It now behaves in the same way as
118        GNU grep.
120    13. If the -o and -v options were combined for pcregrep, it printed a blank
121        line for every non-matching line. GNU grep prints nothing, and pcregrep now
122        does the same. The return code can be used to tell if there were any
123        non-matching lines.
125    14. Added --file-offsets and --line-offsets to pcregrep.
127    15. The pattern (?=something)(?R) was not being diagnosed as a potentially
128        infinitely looping recursion. The bug was that positive lookaheads were not
129        being skipped when checking for a possible empty match (negative lookaheads
130        and both kinds of lookbehind were skipped).
132    16. Fixed two typos in the Windows-only code in pcregrep.c, and moved the
133        inclusion of <windows.h> to before rather than after the definition of
134        INVALID_FILE_ATTRIBUTES (patch from David Byron).
136    17. Specifying a possessive quantifier with a specific limit for a Unicode
137        character property caused pcre_compile() to compile bad code, which led at
138        runtime to PCRE_ERROR_INTERNAL (-14). Examples of patterns that caused this
139        are: /\p{Zl}{2,3}+/8 and /\p{Cc}{2}+/8. It was the possessive "+" that
140        caused the error; without that there was no problem.
142    18. Added --enable-pcregrep-libz and --enable-pcregrep-libbz2.
144    19. Added --enable-pcretest-libreadline.
146    20. In pcrecpp.cc, the variable 'count' was incremented twice in
147        RE::GlobalReplace(). As a result, the number of replacements returned was
148        double what it should be. I removed one of the increments, but Craig sent a
149        later patch that removed the other one (the right fix) and added unit tests
150        that check the return values (which was not done before).
152    21. Several CMake things:
154        (1) Arranged that, when cmake is used on Unix, the libraries end up with
155            the names libpcre and libpcreposix, not just pcre and pcreposix.
157        (2) The above change means that pcretest and pcregrep are now correctly
158            linked with the newly-built libraries, not previously installed ones.
162    22. In UTF-8 mode, with newline set to "any", a pattern such as .*a.*=.b.*
163        crashed when matching a string such as a\x{2029}b (note that \x{2029} is a
164        UTF-8 newline character). The key issue is that the pattern starts .*;
165        this means that the match must be either at the beginning, or after a
166        newline. The bug was in the code for advancing after a failed match and
167        checking that the new position followed a newline. It was not taking
168        account of UTF-8 characters correctly.
170    23. PCRE was behaving differently from Perl in the way it recognized POSIX
171        character classes. PCRE was not treating the sequence [:...:] as a
172        character class unless the ... were all letters. Perl, however, seems to
173        allow any characters between [: and :], though of course it rejects as
174        unknown any "names" that contain non-letters, because all the known class
175        names consist only of letters. Thus, Perl gives an error for [[:1234:]],
176        for example, whereas PCRE did not - it did not recognize a POSIX character
177        class. This seemed a bit dangerous, so the code has been changed to be
178        closer to Perl. The behaviour is not identical to Perl, because PCRE will
179        diagnose an unknown class for, for example, [[:l\ower:]] where Perl will
180        treat it as [[:lower:]]. However, PCRE does now give "unknown" errors where
181        Perl does, and where it didn't before.
183    24. Rewrite so as to remove the single use of %n from pcregrep because in some
184        Windows environments %n is disabled by default.
187    Version 7.4 21-Sep-07
188    ---------------------
190    1.  Change 7.3/28 was implemented for classes by looking at the bitmap. This
191        means that a class such as [\s] counted as "explicit reference to CR or
192        LF". That isn't really right - the whole point of the change was to try to
193        help when there was an actual mention of one of the two characters. So now
194        the change happens only if \r or \n (or a literal CR or LF) character is
195        encountered.
197    2.  The 32-bit options word was also used for 6 internal flags, but the numbers
198        of both had grown to the point where there were only 3 bits left.
199        Fortunately, there was spare space in the data structure, and so I have
200        moved the internal flags into a new 16-bit field to free up more option
201        bits.
203    3.  The appearance of (?J) at the start of a pattern set the DUPNAMES option,
204        but did not set the internal JCHANGED flag - either of these is enough to
205        control the way the "get" function works - but the PCRE_INFO_JCHANGED
206        facility is supposed to tell if (?J) was ever used, so now (?J) at the
207        start sets both bits.
209    4.  Added options (at build time, compile time, exec time) to change \R from
210        matching any Unicode line ending sequence to just matching CR, LF, or CRLF.
212    5.  doc/pcresyntax.html was missing from the distribution.
214    6.  Put back the definition of PCRE_ERROR_NULLWSLIMIT, for backward
215        compatibility, even though it is no longer used.
217    7.  Added macro for snprintf to pcrecpp_unittest.cc and also for strtoll and
218        strtoull to pcrecpp.cc to select the available functions in WIN32 when the
219        windows.h file is present (where different names are used). [This was
220        reversed later after testing - see 16 below.]
222    8.  Changed all #include <config.h> to #include "config.h". There were also
223        some further <pcre.h> cases that I changed to "pcre.h".
225    9.  When pcregrep was used with the --colour option, it missed the line ending
226        sequence off the lines that it output.
228    10. It was pointed out to me that arrays of string pointers cause lots of
229        relocations when a shared library is dynamically loaded. A technique of
230        using a single long string with a table of offsets can drastically reduce
231        these. I have refactored PCRE in four places to do this. The result is
232        dramatic:
234          Originally:                          290
235          After changing UCP table:            187
236          After changing error message table:   43
237          After changing table of "verbs"       36
238          After changing table of Posix names   22
240        Thanks to the folks working on Gregex for glib for this insight.
242    11. --disable-stack-for-recursion caused compiling to fail unless -enable-
243        unicode-properties was also set.
245    12. Updated the tests so that they work when \R is defaulted to ANYCRLF.
247    13. Added checks for ANY and ANYCRLF to pcrecpp.cc where it previously
248        checked only for CRLF.
250    14. Added casts to pcretest.c to avoid compiler warnings.
252    15. Added Craig's patch to various pcrecpp modules to avoid compiler warnings.
254    16. Added Craig's patch to remove the WINDOWS_H tests, that were not working,
255        and instead check for _strtoi64 explicitly, and avoid the use of snprintf()
256        entirely. This removes changes made in 7 above.
258    17. The CMake files have been updated, and there is now more information about
259        building with CMake in the NON-UNIX-USE document.
262    Version 7.3 28-Aug-07
263    ---------------------
265     1. In the rejigging of the build system that eventually resulted in 7.1, the
266        line "#include <pcre.h>" was included in pcre_internal.h. The use of angle
267        brackets there is not right, since it causes compilers to look for an
268        installed pcre.h, not the version that is in the source that is being
269        compiled (which of course may be different). I have changed it back to:
271          #include "pcre.h"
273        I have a vague recollection that the change was concerned with compiling in
274        different directories, but in the new build system, that is taken care of
275        by the VPATH setting the Makefile.
277     2. The pattern .*$ when run in not-DOTALL UTF-8 mode with newline=any failed
278        when the subject happened to end in the byte 0x85 (e.g. if the last
279        character was \x{1ec5}). *Character* 0x85 is one of the "any" newline
280        characters but of course it shouldn't be taken as a newline when it is part
281        of another character. The bug was that, for an unlimited repeat of . in
282        not-DOTALL UTF-8 mode, PCRE was advancing by bytes rather than by
283        characters when looking for a newline.
285     3. A small performance improvement in the DOTALL UTF-8 mode .* case.
287     4. Debugging: adjusted the names of opcodes for different kinds of parentheses
288        in debug output.
290     5. Arrange to use "%I64d" instead of "%lld" and "%I64u" instead of "%llu" for
291        long printing in the pcrecpp unittest when running under MinGW.
293     6. ESC_K was left out of the EBCDIC table.
295     7. Change 7.0/38 introduced a new limit on the number of nested non-capturing
296        parentheses; I made it 1000, which seemed large enough. Unfortunately, the
297        limit also applies to "virtual nesting" when a pattern is recursive, and in
298        this case 1000 isn't so big. I have been able to remove this limit at the
299        expense of backing off one optimization in certain circumstances. Normally,
300        when pcre_exec() would call its internal match() function recursively and
301        immediately return the result unconditionally, it uses a "tail recursion"
302        feature to save stack. However, when a subpattern that can match an empty
303        string has an unlimited repetition quantifier, it no longer makes this
304        optimization. That gives it a stack frame in which to save the data for
305        checking that an empty string has been matched. Previously this was taken
306        from the 1000-entry workspace that had been reserved. So now there is no
307        explicit limit, but more stack is used.
309     8. Applied Daniel's patches to solve problems with the import/export magic
310        syntax that is required for Windows, and which was going wrong for the
311        pcreposix and pcrecpp parts of the library. These were overlooked when this
312        problem was solved for the main library.
314     9. There were some crude static tests to avoid integer overflow when computing
315        the size of patterns that contain repeated groups with explicit upper
316        limits. As the maximum quantifier is 65535, the maximum group length was
317        set at 30,000 so that the product of these two numbers did not overflow a
318        32-bit integer. However, it turns out that people want to use groups that
319        are longer than 30,000 bytes (though not repeat them that many times).
320        Change 7.0/17 (the refactoring of the way the pattern size is computed) has
321        made it possible to implement the integer overflow checks in a much more
322        dynamic way, which I have now done. The artificial limitation on group
323        length has been removed - we now have only the limit on the total length of
324        the compiled pattern, which depends on the LINK_SIZE setting.
326    10. Fixed a bug in the documentation for get/copy named substring when
327        duplicate names are permitted. If none of the named substrings are set, the
328        functions return PCRE_ERROR_NOSUBSTRING (7); the doc said they returned an
329        empty string.
331    11. Because Perl interprets \Q...\E at a high level, and ignores orphan \E
332        instances, patterns such as [\Q\E] or [\E] or even [^\E] cause an error,
333        because the ] is interpreted as the first data character and the
334        terminating ] is not found. PCRE has been made compatible with Perl in this
335        regard. Previously, it interpreted [\Q\E] as an empty class, and [\E] could
336        cause memory overwriting.
338    10. Like Perl, PCRE automatically breaks an unlimited repeat after an empty
339        string has been matched (to stop an infinite loop). It was not recognizing
340        a conditional subpattern that could match an empty string if that
341        subpattern was within another subpattern. For example, it looped when
342        trying to match  (((?(1)X|))*)  but it was OK with  ((?(1)X|)*)  where the
343        condition was not nested. This bug has been fixed.
345    12. A pattern like \X?\d or \P{L}?\d in non-UTF-8 mode could cause a backtrack
346        past the start of the subject in the presence of bytes with the top bit
347        set, for example "\x8aBCD".
349    13. Added Perl 5.10 experimental backtracking controls (*FAIL), (*F), (*PRUNE),
350        (*SKIP), (*THEN), (*COMMIT), and (*ACCEPT).
352    14. Optimized (?!) to (*FAIL).
354    15. Updated the test for a valid UTF-8 string to conform to the later RFC 3629.
355        This restricts code points to be within the range 0 to 0x10FFFF, excluding
356        the "low surrogate" sequence 0xD800 to 0xDFFF. Previously, PCRE allowed the
357        full range 0 to 0x7FFFFFFF, as defined by RFC 2279. Internally, it still
358        does: it's just the validity check that is more restrictive.
360    16. Inserted checks for integer overflows during escape sequence (backslash)
361        processing, and also fixed erroneous offset values for syntax errors during
362        backslash processing.
364    17. Fixed another case of looking too far back in non-UTF-8 mode (cf 12 above)
365        for patterns like [\PPP\x8a]{1,}\x80 with the subject "A\x80".
367    18. An unterminated class in a pattern like (?1)\c[ with a "forward reference"
368        caused an overrun.
370    19. A pattern like (?:[\PPa*]*){8,} which had an "extended class" (one with
371        something other than just ASCII characters) inside a group that had an
372        unlimited repeat caused a loop at compile time (while checking to see
373        whether the group could match an empty string).
375    20. Debugging a pattern containing \p or \P could cause a crash. For example,
376        [\P{Any}] did so. (Error in the code for printing property names.)
378    21. An orphan \E inside a character class could cause a crash.
380    22. A repeated capturing bracket such as (A)? could cause a wild memory
381        reference during compilation.
383    23. There are several functions in pcre_compile() that scan along a compiled
384        expression for various reasons (e.g. to see if it's fixed length for look
385        behind). There were bugs in these functions when a repeated \p or \P was
386        present in the pattern. These operators have additional parameters compared
387        with \d, etc, and these were not being taken into account when moving along
388        the compiled data. Specifically:
390        (a) A item such as \p{Yi}{3} in a lookbehind was not treated as fixed
391            length.
393        (b) An item such as \pL+ within a repeated group could cause crashes or
394            loops.
396        (c) A pattern such as \p{Yi}+(\P{Yi}+)(?1) could give an incorrect
397            "reference to non-existent subpattern" error.
399        (d) A pattern like (\P{Yi}{2}\277)? could loop at compile time.
401    24. A repeated \S or \W in UTF-8 mode could give wrong answers when multibyte
402        characters were involved (for example /\S{2}/8g with "A\x{a3}BC").
404    25. Using pcregrep in multiline, inverted mode (-Mv) caused it to loop.
406    26. Patterns such as [\P{Yi}A] which include \p or \P and just one other
407        character were causing crashes (broken optimization).
409    27. Patterns such as (\P{Yi}*\277)* (group with possible zero repeat containing
410        \p or \P) caused a compile-time loop.
412    28. More problems have arisen in unanchored patterns when CRLF is a valid line
413        break. For example, the unstudied pattern [\r\n]A does not match the string
414        "\r\nA" because change 7.0/46 below moves the current point on by two
415        characters after failing to match at the start. However, the pattern \nA
416        *does* match, because it doesn't start till \n, and if [\r\n]A is studied,
417        the same is true. There doesn't seem any very clean way out of this, but
418        what I have chosen to do makes the common cases work: PCRE now takes note
419        of whether there can be an explicit match for \r or \n anywhere in the
420        pattern, and if so, 7.0/46 no longer applies. As part of this change,
421        there's a new PCRE_INFO_HASCRORLF option for finding out whether a compiled
422        pattern has explicit CR or LF references.
424    29. Added (*CR) etc for changing newline setting at start of pattern.
427    Version 7.2 19-Jun-07
428    ---------------------
430     1. If the fr_FR locale cannot be found for test 3, try the "french" locale,
431        which is apparently normally available under Windows.
433     2. Re-jig the pcregrep tests with different newline settings in an attempt
434        to make them independent of the local environment's newline setting.
436     3. Add code to configure.ac to remove -g from the CFLAGS default settings.
438     4. Some of the "internals" tests were previously cut out when the link size
439        was not 2, because the output contained actual offsets. The recent new
440        "Z" feature of pcretest means that these can be cut out, making the tests
441        usable with all link sizes.
443     5. Implemented Stan Switzer's goto replacement for longjmp() when not using
444        stack recursion. This gives a massive performance boost under BSD, but just
445        a small improvement under Linux. However, it saves one field in the frame
446        in all cases.
448     6. Added more features from the forthcoming Perl 5.10:
450        (a) (?-n) (where n is a string of digits) is a relative subroutine or
451            recursion call. It refers to the nth most recently opened parentheses.
453        (b) (?+n) is also a relative subroutine call; it refers to the nth next
454            to be opened parentheses.
456        (c) Conditions that refer to capturing parentheses can be specified
457            relatively, for example, (?(-2)... or (?(+3)...
459        (d) \K resets the start of the current match so that everything before
460            is not part of it.
462        (e) \k{name} is synonymous with \k<name> and \k'name' (.NET compatible).
464        (f) \g{name} is another synonym - part of Perl 5.10's unification of
465            reference syntax.
467        (g) (?| introduces a group in which the numbering of parentheses in each
468            alternative starts with the same number.
470        (h) \h, \H, \v, and \V match horizontal and vertical whitespace.
472     7. Added two new calls to pcre_fullinfo(): PCRE_INFO_OKPARTIAL and
475     8. A pattern such as  (.*(.)?)*  caused pcre_exec() to fail by either not
476        terminating or by crashing. Diagnosed by Viktor Griph; it was in the code
477        for detecting groups that can match an empty string.
479     9. A pattern with a very large number of alternatives (more than several
480        hundred) was running out of internal workspace during the pre-compile
481        phase, where pcre_compile() figures out how much memory will be needed. A
482        bit of new cunning has reduced the workspace needed for groups with
483        alternatives. The 1000-alternative test pattern now uses 12 bytes of
484        workspace instead of running out of the 4096 that are available.
486    10. Inserted some missing (unsigned int) casts to get rid of compiler warnings.
488    11. Applied patch from Google to remove an optimization that didn't quite work.
489        The report of the bug said:
491          pcrecpp::RE("a*").FullMatch("aaa") matches, while
492          pcrecpp::RE("a*?").FullMatch("aaa") does not, and
493          pcrecpp::RE("a*?\\z").FullMatch("aaa") does again.
495    12. If \p or \P was used in non-UTF-8 mode on a character greater than 127
496        it matched the wrong number of bytes.
499    Version 7.1 24-Apr-07
500    ---------------------
502     1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
503        that is more "standard", making use of automake and other Autotools. There
504        is some re-arrangement of the files and adjustment of comments consequent
505        on this.
507     2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
508        for recursive directory scanning broke on some systems because the files
509        are not scanned in any specific order and on different systems the order
510        was different. A call to "sort" has been inserted into RunGrepTest for the
511        approprate test as a short-term fix. In the longer term there may be an
512        alternative.
514     3. I had an email from Eric Raymond about problems translating some of PCRE's
515        man pages to HTML (despite the fact that I distribute HTML pages, some
516        people do their own conversions for various reasons). The problems
517        concerned the use of low-level troff macros .br and .in. I have therefore
518        removed all such uses from the man pages (some were redundant, some could
519        be replaced by .nf/.fi pairs). The 132html script that I use to generate
520        HTML has been updated to handle .nf/.fi and to complain if it encounters
521        .br or .in.
523     4. Updated comments in configure.ac that get placed in config.h.in and also
524        arranged for config.h to be included in the distribution, with the name
525        config.h.generic, for the benefit of those who have to compile without
526        Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
528     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
529        Weber: (1) pcre_internal.h was missing some function renames; (2) updated
530        makevp.bat for the current PCRE, using the additional files
531        makevp_c.txt, makevp_l.txt, and pcregexp.pas.
533     6. A Windows user reported a minor discrepancy with test 2, which turned out
534        to be caused by a trailing space on an input line that had got lost in his
535        copy. The trailing space was an accident, so I've just removed it.
537     7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
538        that is needed.
540     8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
541        as "const" (a) because they are and (b) because it helps the PHP
542        maintainers who have recently made a script to detect big data structures
543        in the php code that should be moved to the .rodata section. I remembered
544        to update Builducptable as well, so it won't revert if ucptable.h is ever
545        re-created.
547     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
548        pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
549        order to be able to cut out the UTF-8 tables in the latter when UTF-8
550        support is not required. This saves 1.5-2K of code, which is important in
551        some applications.
553        Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
554        so as not to refer to the tables, even though these functions will never be
555        called when UTF-8 support is disabled. Otherwise there are problems with a
556        shared library.
558    10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
560        (a) It was defining its arguments as char * instead of void *.
562        (b) It was assuming that all moves were upwards in memory; this was true
563            a long time ago when I wrote it, but is no longer the case.
565        The emulated memove() is provided for those environments that have neither
566        memmove() nor bcopy(). I didn't think anyone used it these days, but that
567        is clearly not the case, as these two bugs were recently reported.
569    11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
570        and Detrail to create the HTML documentation, the .txt form of the man
571        pages, and it removes trailing spaces from listed files. It also creates
572        pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
573        case, it wraps all the #defines with #ifndefs. This script should be run
574        before "make dist".
576    12. Fixed two fairly obscure bugs concerned with quantified caseless matching
577        with Unicode property support.
579        (a) For a maximizing quantifier, if the two different cases of the
580            character were of different lengths in their UTF-8 codings (there are
581            some cases like this - I found 11), and the matching function had to
582            back up over a mixture of the two cases, it incorrectly assumed they
583            were both the same length.
585        (b) When PCRE was configured to use the heap rather than the stack for
586            recursion during matching, it was not correctly preserving the data for
587            the other case of a UTF-8 character when checking ahead for a match
588            while processing a minimizing repeat. If the check also involved
589            matching a wide character, but failed, corruption could cause an
590            erroneous result when trying to check for a repeat of the original
591            character.
593    13. Some tidying changes to the testing mechanism:
595        (a) The RunTest script now detects the internal link size and whether there
596            is UTF-8 and UCP support by running ./pcretest -C instead of relying on
597            values substituted by "configure". (The RunGrepTest script already did
598            this for UTF-8.) The configure.ac script no longer substitutes the
599            relevant variables.
601        (b) The debugging options /B and /D in pcretest show the compiled bytecode
602            with length and offset values. This means that the output is different
603            for different internal link sizes. Test 2 is skipped for link sizes
604            other than 2 because of this, bypassing the problem. Unfortunately,
605            there was also a test in test 3 (the locale tests) that used /B and
606            failed for link sizes other than 2. Rather than cut the whole test out,
607            I have added a new /Z option to pcretest that replaces the length and
608            offset values with spaces. This is now used to make test 3 independent
609            of link size. (Test 2 will be tidied up later.)
611    14. If erroroffset was passed as NULL to pcre_compile, it provoked a
612        segmentation fault instead of returning the appropriate error message.
614    15. In multiline mode when the newline sequence was set to "any", the pattern
615        ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
616        This doesn't seem right; it now treats the CRLF combination as the line
617        ending, and so does not match in that case. It's only a pattern such as ^$
618        that would hit this one: something like ^ABC$ would have failed after \r
619        and then tried again after \r\n.
621    16. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
622        in an attempt to make files that differ only in their line terminators
623        compare equal. This works on Linux.
625    17. Under certain error circumstances pcregrep might try to free random memory
626        as it exited. This is now fixed, thanks to valgrind.
628    19. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
629        "abc\r\n\r\n", it found an unwanted second match after the second \r. This
630        was because its rules for how to advance for /g after matching an empty
631        string at the end of a line did not allow for this case. They now check for
632        it specially.
634    20. pcretest is supposed to handle patterns and data of any length, by
635        extending its buffers when necessary. It was getting this wrong when the
636        buffer for a data line had to be extended.
638    21. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or
639        CRLF as a newline sequence.
641    22. Code for handling Unicode properties in pcre_dfa_exec() wasn't being cut
642        out by #ifdef SUPPORT_UCP. This did no harm, as it could never be used, but
643        I have nevertheless tidied it up.
645    23. Added some casts to kill warnings from HP-UX ia64 compiler.
647    24. Added a man page for pcre-config.
650    Version 7.0 19-Dec-06
651    ---------------------
653     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
654        moving to gcc 4.1.1.
656     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
657        sys/time.h, which is documented as needed for this function. It doesn't
658        seem to matter on Linux, but it showed up on some releases of OS X.
660     3. It seems that there are systems where bytes whose values are greater than
661        127 match isprint() in the "C" locale. The "C" locale should be the
662        default when a C program starts up. In most systems, only ASCII printing
663        characters match isprint(). This difference caused the output from pcretest
664        to vary, making some of the tests fail. I have changed pcretest so that:
666        (a) When it is outputting text in the compiled version of a pattern, bytes
667            other than 32-126 are always shown as hex escapes.
669        (b) When it is outputting text that is a matched part of a subject string,
670            it does the same, unless a different locale has been set for the match
671            (using the /L modifier). In this case, it uses isprint() to decide.
673     4. Fixed a major bug that caused incorrect computation of the amount of memory
674        required for a compiled pattern when options that changed within the
675        pattern affected the logic of the preliminary scan that determines the
676        length. The relevant options are -x, and -i in UTF-8 mode. The result was
677        that the computed length was too small. The symptoms of this bug were
678        either the PCRE error "internal error: code overflow" from pcre_compile(),
679        or a glibc crash with a message such as "pcretest: free(): invalid next
680        size (fast)". Examples of patterns that provoked this bug (shown in
681        pcretest format) are:
683          /(?-x: )/x
684          /(?x)(?-x: \s*#\s*)/
685          /((?i)[\x{c0}])/8
686          /(?i:[\x{c0}])/8
688        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
689        is now done differently.
691     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
692        wrapper classes; (b) implement a new function in the C++ scanner that is
693        more efficient than the old way of doing things because it avoids levels of
694        recursion in the regex matching; (c) add a paragraph to the documentation
695        for the FullMatch() function.
697     6. The escape sequence \n was being treated as whatever was defined as
698        "newline". Not only was this contrary to the documentation, which states
699        that \n is character 10 (hex 0A), but it also went horribly wrong when
700        "newline" was defined as CRLF. This has been fixed.
702     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
703        was being set to -1 for the "end of line" case (supposedly a value that no
704        character can have). Though this value is never used (the check for end of
705        line is "zero bytes in current character"), it caused compiler complaints.
706        I've changed it to 0xffffffff.
708     8. In pcre_version.c, the version string was being built by a sequence of
709        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
710        string (as it is for production releases) called a macro with an empty
711        argument. The C standard says the result of this is undefined. The gcc
712        compiler treats it as an empty string (which was what was wanted) but it is
713        reported that Visual C gives an error. The source has been hacked around to
714        avoid this problem.
716     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
717        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
718        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
719        of them did).
721    10. Originally, pcretest opened its input and output without "b"; then I was
722        told that "b" was needed in some environments, so it was added for release
723        5.0 to both the input and output. (It makes no difference on Unix-like
724        systems.) Later I was told that it is wrong for the input on Windows. I've
725        now abstracted the modes into two macros, to make it easier to fiddle with
726        them, and removed "b" from the input mode under Windows.
728    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
730    12. Added -help and --help to pcretest as an official way of being reminded
731        of the options.
733    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
734        and pcrecpp.cc because they annoy compilers at high warning levels.
736    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
738    15. Fixed an occurrence of == in configure.ac that should have been = (shell
739        scripts are not C programs :-) and which was not noticed because it works
740        on Linux.
742    16. pcretest is supposed to handle any length of pattern and data line (as one
743        line or as a continued sequence of lines) by extending its input buffer if
744        necessary. This feature was broken for very long pattern lines, leading to
745        a string of junk being passed to pcre_compile() if the pattern was longer
746        than about 50K.
748    17. I have done a major re-factoring of the way pcre_compile() computes the
749        amount of memory needed for a compiled pattern. Previously, there was code
750        that made a preliminary scan of the pattern in order to do this. That was
751        OK when PCRE was new, but as the facilities have expanded, it has become
752        harder and harder to keep it in step with the real compile phase, and there
753        have been a number of bugs (see for example, 4 above). I have now found a
754        cunning way of running the real compile function in a "fake" mode that
755        enables it to compute how much memory it would need, while actually only
756        ever using a few hundred bytes of working memory and without too many
757        tests of the mode. This should make future maintenance and development
758        easier. A side effect of this work is that the limit of 200 on the nesting
759        depth of parentheses has been removed (though this was never a serious
760        limitation, I suspect). However, there is a downside: pcre_compile() now
761        runs more slowly than before (30% or more, depending on the pattern). I
762        hope this isn't a big issue. There is no effect on runtime performance.
764    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
765        newline (only possible for the last line of a file) and it was a
766        pattern that set a locale (followed by /Lsomething), pcretest crashed.
768    19. Added additional timing features to pcretest. (1) The -tm option now times
769        matching only, not compiling. (2) Both -t and -tm can be followed, as a
770        separate command line item, by a number that specifies the number of
771        repeats to use when timing. The default is 50000; this gives better
772        precision, but takes uncomfortably long for very large patterns.
774    20. Extended pcre_study() to be more clever in cases where a branch of a
775        subpattern has no definite first character. For example, (a*|b*)[cd] would
776        previously give no result from pcre_study(). Now it recognizes that the
777        first character must be a, b, c, or d.
779    21. There was an incorrect error "recursive call could loop indefinitely" if
780        a subpattern (or the entire pattern) that was being tested for matching an
781        empty string contained only one non-empty item after a nested subpattern.
782        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
783        incorrectly, because the \d was being skipped in the check.
785    22. The pcretest program now has a new pattern option /B and a command line
786        option -b, which is equivalent to adding /B to every pattern. This causes
787        it to show the compiled bytecode, without the additional information that
788        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
789        is the same as /B/I).
791    23. A new optimization is now able automatically to treat some sequences such
792        as a*b as a*+b. More specifically, if something simple (such as a character
793        or a simple class like \d) has an unlimited quantifier, and is followed by
794        something that cannot possibly match the quantified thing, the quantifier
795        is automatically "possessified".
797    24. A recursive reference to a subpattern whose number was greater than 39
798        went wrong under certain circumstances in UTF-8 mode. This bug could also
799        have affected the operation of pcre_study().
801    25. Realized that a little bit of performance could be had by replacing
802        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
804    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
806    27. Possessive quantifiers such as a++ were previously implemented by turning
807        them into atomic groups such as ($>a+). Now they have their own opcodes,
808        which improves performance. This includes the automatically created ones
809        from 23 above.
811    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
812        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
813        the first matched character to be a colon. This applied both to named and
814        numbered groups.
816    29. The ucpinternal.h header file was missing its idempotency #ifdef.
818    30. I was sent a "project" file called libpcre.a.dev which I understand makes
819        building PCRE on Windows easier, so I have included it in the distribution.
821    31. There is now a check in pcretest against a ridiculously large number being
822        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
823        loop, the loop is abandoned.
825    32. Forward references to subpatterns in conditions such as (?(2)...) where
826        subpattern 2 is defined later cause pcre_compile() to search forwards in
827        the pattern for the relevant set of parentheses. This search went wrong
828        when there were unescaped parentheses in a character class, parentheses
829        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
831    33. "Subroutine" calls and backreferences were previously restricted to
832        referencing subpatterns earlier in the regex. This restriction has now
833        been removed.
835    34. Added a number of extra features that are going to be in Perl 5.10. On the
836        whole, these are just syntactic alternatives for features that PCRE had
837        previously implemented using the Python syntax or my own invention. The
838        other formats are all retained for compatibility.
840        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
841            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
842            also .NET compatible.
844        (b) A recursion or subroutine call to a named group can now be defined as
845            (?&name) as well as (?P>name).
847        (c) A backreference to a named group can now be defined as \k<name> or
848            \k'name' as well as (?P=name). The new forms, as well as being in Perl
849            5.10, are also .NET compatible.
851        (d) A conditional reference to a named group can now use the syntax
852            (?(<name>) or (?('name') as well as (?(name).
854        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
855            groups (named and numbered) that are never evaluated inline, but can be
856            called as "subroutines" from elsewhere. In effect, the DEFINE condition
857            is always false. There may be only one alternative in such a group.
859        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
860            as the simple (?(R). The condition is true only if the most recent
861            recursion is that of the given number or name. It does not search out
862            through the entire recursion stack.
864        (g) The escape \gN or \g{N} has been added, where N is a positive or
865            negative number, specifying an absolute or relative reference.
867    35. Tidied to get rid of some further signed/unsigned compiler warnings and
868        some "unreachable code" warnings.
870    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
871        things, this adds five new scripts.
873    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
874        There were also incompatibilities regarding the handling of \Q..\E inside
875        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
876        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
878    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
879        matches an empty string, and forcibly breaks the loop. There were bugs in
880        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
881        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
882        separate and independent bugs (that affected different cases) have been
883        fixed.
885    39. Refactored the code to abolish the use of different opcodes for small
886        capturing bracket numbers. This is a tidy that I avoided doing when I
887        removed the limit on the number of capturing brackets for 3.5 back in 2001.
888        The new approach is not only tidier, it makes it possible to reduce the
889        memory needed to fix the previous bug (38).
891    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
892        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
893        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
894        mode.
896    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
897        report.
899    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
900        copy construction and assignment in the C++ wrapper.
902    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
903        couple of bugs that could have given wrong results in the "--newline=crlf"
904        case.
906    44. Added a number of casts and did some reorganization of signed/unsigned int
907        variables following suggestions from Dair Grant. Also renamed the variable
908        "this" as "item" because it is a C++ keyword.
910    45. Arranged for dftables to add
912          #include "pcre_internal.h"
914        to pcre_chartables.c because without it, gcc 4.x may remove the array
915        definition from the final binary if PCRE is built into a static library and
916        dead code stripping is activated.
918    46. For an unanchored pattern, if a match attempt fails at the start of a
919        newline sequence, and the newline setting is CRLF or ANY, and the next two
920        characters are CRLF, advance by two characters instead of one.
923    Version 6.7 04-Jul-06
924    ---------------------
926     1. In order to handle tests when input lines are enormously long, pcretest has
927        been re-factored so that it automatically extends its buffers when
928        necessary. The code is crude, but this _is_ just a test program. The
929        default size has been increased from 32K to 50K.
931     2. The code in pcre_study() was using the value of the re argument before
932        testing it for NULL. (Of course, in any sensible call of the function, it
933        won't be NULL.)
935     3. The memmove() emulation function in pcre_internal.h, which is used on
936        systems that lack both memmove() and bcopy() - that is, hardly ever -
937        was missing a "static" storage class specifier.
939     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
940        containing an extended class (one that cannot be represented by a bitmap
941        because it contains high-valued characters or Unicode property items, e.g.
942        [\pZ]). Almost always one would set UTF-8 mode when processing such a
943        pattern, but PCRE should not loop if you do not (it no longer does).
944        [Detail: two cases were found: (a) a repeated subpattern containing an
945        extended class; (b) a recursive reference to a subpattern that followed a
946        previous extended class. It wasn't skipping over the extended class
947        correctly when UTF-8 mode was not set.]
949     5. A negated single-character class was not being recognized as fixed-length
950        in lookbehind assertions such as (?<=[^f]), leading to an incorrect
951        compile error "lookbehind assertion is not fixed length".
953     6. The RunPerlTest auxiliary script was showing an unexpected difference
954        between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
955        write a Perl script that can interpret lines of an input file either as
956        byte characters or as UTF-8, which is what "perltest" was being required to
957        do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
958        can't do is switch easily at run time between having the "use utf8;" pragma
959        or not. In the end, I fudged it by using the RunPerlTest script to insert
960        "use utf8;" explicitly for the UTF-8 tests.
962     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
963        the end of the subject string, contrary to the documentation and to what
964        Perl does. This was true of both matching functions. Now it matches only at
965        the start of the subject and immediately after *internal* newlines.
967     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
968        a pointer to an int instead of a pointer to an unsigned long int. This
969        caused problems on 64-bit systems.
971     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
972        instance of the 'standard' template library not being so standard".
974    10. There was no check on the number of named subpatterns nor the maximum
975        length of a subpattern name. The product of these values is used to compute
976        the size of the memory block for a compiled pattern. By supplying a very
977        long subpattern name and a large number of named subpatterns, the size
978        computation could be caused to overflow. This is now prevented by limiting
979        the length of names to 32 characters, and the number of named subpatterns
980        to 10,000.
982    11. Subpatterns that are repeated with specific counts have to be replicated in
983        the compiled pattern. The size of memory for this was computed from the
984        length of the subpattern and the repeat count. The latter is limited to
985        65535, but there was no limit on the former, meaning that integer overflow
986        could in principle occur. The compiled length of a repeated subpattern is
987        now limited to 30,000 bytes in order to prevent this.
989    12. Added the optional facility to have named substrings with the same name.
991    13. Added the ability to use a named substring as a condition, using the
992        Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
993        are numbers (not recommended). Forward references are permitted.
995    14. Added forward references in named backreferences (if you see what I mean).
997    15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
998        pattern could run off the end of the subject. For example, the pattern
999        "(?s)(.{1,5})"8 did this with the subject "ab".
1001    16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
1002        PCRE_CASELESS was set when matching characters that were quantified with ?
1003        or *.
1005    17. A character class other than a single negated character that had a minimum
1006        but no maximum quantifier - for example [ab]{6,} - was not handled
1007        correctly by pce_dfa_exec(). It would match only one character.
1009    18. A valid (though odd) pattern that looked like a POSIX character
1010        class but used an invalid character after [ (for example [[,abc,]]) caused
1011        pcre_compile() to give the error "Failed: internal error: code overflow" or
1012        in some cases to crash with a glibc free() error. This could even happen if
1013        the pattern terminated after [[ but there just happened to be a sequence of
1014        letters, a binary zero, and a closing ] in the memory that followed.
1016    19. Perl's treatment of octal escapes in the range \400 to \777 has changed
1017        over the years. Originally (before any Unicode support), just the bottom 8
1018        bits were taken. Thus, for example, \500 really meant \100. Nowadays the
1019        output from "man perlunicode" includes this:
1021          The regular expression compiler produces polymorphic opcodes.  That
1022          is, the pattern adapts to the data and automatically switches to
1023          the Unicode character scheme when presented with Unicode data--or
1024          instead uses a traditional byte scheme when presented with byte
1025          data.
1027        Sadly, a wide octal escape does not cause a switch, and in a string with
1028        no other multibyte characters, these octal escapes are treated as before.
1029        Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
1030        /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
1031        Unicode string.
1033        I have not perpetrated such confusion in PCRE. Up till now, it took just
1034        the bottom 8 bits, as in old Perl. I have now made octal escapes with
1035        values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
1036        translate to the appropriate multibyte character.
1038    29. Applied some refactoring to reduce the number of warnings from Microsoft
1039        and Borland compilers. This has included removing the fudge introduced
1040        seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
1041        a warning about an unused variable.
1043    21. PCRE has not included VT (character 0x0b) in the set of whitespace
1044        characters since release 4.0, because Perl (from release 5.004) does not.
1045        [Or at least, is documented not to: some releases seem to be in conflict
1046        with the documentation.] However, when a pattern was studied with
1047        pcre_study() and all its branches started with \s, PCRE still included VT
1048        as a possible starting character. Of course, this did no harm; it just
1049        caused an unnecessary match attempt.
1051    22. Removed a now-redundant internal flag bit that recorded the fact that case
1052        dependency changed within the pattern. This was once needed for "required
1053        byte" processing, but is no longer used. This recovers a now-scarce options
1054        bit. Also moved the least significant internal flag bit to the most-
1055        significant bit of the word, which was not previously used (hangover from
1056        the days when it was an int rather than a uint) to free up another bit for
1057        the future.
1059    23. Added support for CRLF line endings as well as CR and LF. As well as the
1060        default being selectable at build time, it can now be changed at runtime
1061        via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
1062        specify that it is scanning data with non-default line endings.
1064    24. Changed the definition of CXXLINK to make it agree with the definition of
1065        LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
1067    25. Applied Ian Taylor's patches to avoid using another stack frame for tail
1068        recursions. This makes a big different to stack usage for some patterns.
1070    26. If a subpattern containing a named recursion or subroutine reference such
1071        as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
1072        the space required for the compiled pattern went wrong and gave too small a
1073        value. Depending on the environment, this could lead to "Failed: internal
1074        error: code overflow at offset 49" or "glibc detected double free or
1075        corruption" errors.
1077    27. Applied patches from Google (a) to support the new newline modes and (b) to
1078        advance over multibyte UTF-8 characters in GlobalReplace.
1080    28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
1081        difference for some implementation of PCRE in some Windows version.
1083    29. Added some extra testing facilities to pcretest:
1085        \q<number>   in a data line sets the "match limit" value
1086        \Q<number>   in a data line sets the "match recursion limt" value
1087        -S <number>  sets the stack size, where <number> is in megabytes
1089        The -S option isn't available for Windows.
1092    Version 6.6 06-Feb-06
1093    ---------------------
1095     1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
1096        in pcreposix.h. I have copied the definition from pcre.h.
1098     2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
1099        because pcre.h is no longer a built file.
1101     3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
1102        not normally included in the compiled code.
1105    Version 6.5 01-Feb-06
1106    ---------------------
1108     1. When using the partial match feature with pcre_dfa_exec(), it was not
1109        anchoring the second and subsequent partial matches at the new starting
1110        point. This could lead to incorrect results. For example, with the pattern
1111        /1234/, partially matching against "123" and then "a4" gave a match.
1113     2. Changes to pcregrep:
1115        (a) All non-match returns from pcre_exec() were being treated as failures
1116            to match the line. Now, unless the error is PCRE_ERROR_NOMATCH, an
1117            error message is output. Some extra information is given for the
1118            PCRE_ERROR_MATCHLIMIT and PCRE_ERROR_RECURSIONLIMIT errors, which are
1119            probably the only errors that are likely to be caused by users (by
1120            specifying a regex that has nested indefinite repeats, for instance).
1121            If there are more than 20 of these errors, pcregrep is abandoned.
1123        (b) A binary zero was treated as data while matching, but terminated the
1124            output line if it was written out. This has been fixed: binary zeroes
1125            are now no different to any other data bytes.
1127        (c) Whichever of the LC_ALL or LC_CTYPE environment variables is set is
1128            used to set a locale for matching. The --locale=xxxx long option has
1129            been added (no short equivalent) to specify a locale explicitly on the
1130            pcregrep command, overriding the environment variables.
1132        (d) When -B was used with -n, some line numbers in the output were one less
1133            than they should have been.
1135        (e) Added the -o (--only-matching) option.
1137        (f) If -A or -C was used with -c (count only), some lines of context were
1138            accidentally printed for the final match.
1140        (g) Added the -H (--with-filename) option.
1142        (h) The combination of options -rh failed to suppress file names for files
1143            that were found from directory arguments.
1145        (i) Added the -D (--devices) and -d (--directories) options.
1147        (j) Added the -F (--fixed-strings) option.
1149        (k) Allow "-" to be used as a file name for -f as well as for a data file.
1151        (l) Added the --colo(u)r option.
1153        (m) Added Jeffrey Friedl's -S testing option, but within #ifdefs so that it
1154            is not present by default.
1156     3. A nasty bug was discovered in the handling of recursive patterns, that is,
1157        items such as (?R) or (?1), when the recursion could match a number of
1158        alternatives. If it matched one of the alternatives, but subsequently,
1159        outside the recursion, there was a failure, the code tried to back up into
1160        the recursion. However, because of the way PCRE is implemented, this is not
1161        possible, and the result was an incorrect result from the match.
1163        In order to prevent this happening, the specification of recursion has
1164        been changed so that all such subpatterns are automatically treated as
1165        atomic groups. Thus, for example, (?R) is treated as if it were (?>(?R)).
1167     4. I had overlooked the fact that, in some locales, there are characters for
1168        which isalpha() is true but neither isupper() nor islower() are true. In
1169        the fr_FR locale, for instance, the \xAA and \xBA characters (ordmasculine
1170        and ordfeminine) are like this. This affected the treatment of \w and \W
1171        when they appeared in character classes, but not when they appeared outside
1172        a character class. The bit map for "word" characters is now created
1173        separately from the results of isalnum() instead of just taking it from the
1174        upper, lower, and digit maps. (Plus the underscore character, of course.)
1176     5. The above bug also affected the handling of POSIX character classes such as
1177        [[:alpha:]] and [[:alnum:]]. These do not have their own bit maps in PCRE's
1178        permanent tables. Instead, the bit maps for such a class were previously
1179        created as the appropriate unions of the upper, lower, and digit bitmaps.
1180        Now they are created by subtraction from the [[:word:]] class, which has
1181        its own bitmap.
1183     6. The [[:blank:]] character class matches horizontal, but not vertical space.
1184        It is created by subtracting the vertical space characters (\x09, \x0a,
1185        \x0b, \x0c) from the [[:space:]] bitmap. Previously, however, the
1186        subtraction was done in the overall bitmap for a character class, meaning
1187        that a class such as [\x0c[:blank:]] was incorrect because \x0c would not
1188        be recognized. This bug has been fixed.
1190     7. Patches from the folks at Google:
1192          (a) pcrecpp.cc: "to handle a corner case that may or may not happen in
1193          real life, but is still worth protecting against".
1195          (b) pcrecpp.cc: "corrects a bug when negative radixes are used with
1196          regular expressions".
1198          (c) pcre_scanner.cc: avoid use of std::count() because not all systems
1199          have it.
1201          (d) Split off pcrecpparg.h from pcrecpp.h and had the former built by
1202          "configure" and the latter not, in order to fix a problem somebody had
1203          with compiling the Arg class on HP-UX.
1205          (e) Improve the error-handling of the C++ wrapper a little bit.
1207          (f) New tests for checking recursion limiting.
1209     8. The pcre_memmove() function, which is used only if the environment does not
1210        have a standard memmove() function (and is therefore rarely compiled),
1211        contained two bugs: (a) use of int instead of size_t, and (b) it was not
1212        returning a result (though PCRE never actually uses the result).
1214     9. In the POSIX regexec() interface, if nmatch is specified as a ridiculously
1215        large number - greater than INT_MAX/(3*sizeof(int)) - REG_ESPACE is
1216        returned instead of calling malloc() with an overflowing number that would
1217        most likely cause subsequent chaos.
1219    10. The debugging option of pcretest was not showing the NO_AUTO_CAPTURE flag.
1221    11. The POSIX flag REG_NOSUB is now supported. When a pattern that was compiled
1222        with this option is matched, the nmatch and pmatch options of regexec() are
1223        ignored.
1225    12. Added REG_UTF8 to the POSIX interface. This is not defined by POSIX, but is
1226        provided in case anyone wants to the the POSIX interface with UTF-8
1227        strings.
1229    13. Added CXXLDFLAGS to the Makefile parameters to provide settings only on the
1230        C++ linking (needed for some HP-UX environments).
1232    14. Avoid compiler warnings in get_ucpname() when compiled without UCP support
1233        (unused parameter) and in the pcre_printint() function (omitted "default"
1234        switch label when the default is to do nothing).
1236    15. Added some code to make it possible, when PCRE is compiled as a C++
1237        library, to replace subject pointers for pcre_exec() with a smart pointer
1238        class, thus making it possible to process discontinuous strings.
1240    16. The two macros PCRE_EXPORT and PCRE_DATA_SCOPE are confusing, and perform
1241        much the same function. They were added by different people who were trying
1242        to make PCRE easy to compile on non-Unix systems. It has been suggested
1243        that PCRE_EXPORT be abolished now that there is more automatic apparatus
1244        for compiling on Windows systems. I have therefore replaced it with
1245        PCRE_DATA_SCOPE. This is set automatically for Windows; if not set it
1246        defaults to "extern" for C or "extern C" for C++, which works fine on
1247        Unix-like systems. It is now possible to override the value of PCRE_DATA_
1248        SCOPE with something explicit in config.h. In addition:
1250        (a) pcreposix.h still had just "extern" instead of either of these macros;
1251            I have replaced it with PCRE_DATA_SCOPE.
1253        (b) Functions such as _pcre_xclass(), which are internal to the library,
1254            but external in the C sense, all had PCRE_EXPORT in their definitions.
1255            This is apparently wrong for the Windows case, so I have removed it.
1256            (It makes no difference on Unix-like systems.)
1258    17. Added a new limit, MATCH_LIMIT_RECURSION, which limits the depth of nesting
1259        of recursive calls to match(). This is different to MATCH_LIMIT because
1260        that limits the total number of calls to match(), not all of which increase
1261        the depth of recursion. Limiting the recursion depth limits the amount of
1262        stack (or heap if NO_RECURSE is set) that is used. The default can be set
1263        when PCRE is compiled, and changed at run time. A patch from Google adds
1264        this functionality to the C++ interface.
1266    18. Changes to the handling of Unicode character properties:
1268        (a) Updated the table to Unicode 4.1.0.
1270        (b) Recognize characters that are not in the table as "Cn" (undefined).
1272        (c) I revised the way the table is implemented to a much improved format
1273            which includes recognition of ranges. It now supports the ranges that
1274            are defined in UnicodeData.txt, and it also amalgamates other
1275            characters into ranges. This has reduced the number of entries in the
1276            table from around 16,000 to around 3,000, thus reducing its size
1277            considerably. I realized I did not need to use a tree structure after
1278            all - a binary chop search is just as efficient. Having reduced the
1279            number of entries, I extended their size from 6 bytes to 8 bytes to
1280            allow for more data.
1282        (d) Added support for Unicode script names via properties such as \p{Han}.
1284    19. In UTF-8 mode, a backslash followed by a non-Ascii character was not
1285        matching that character.
1287    20. When matching a repeated Unicode property with a minimum greater than zero,
1288        (for example \pL{2,}), PCRE could look past the end of the subject if it
1289        reached it while seeking the minimum number of characters. This could
1290        happen only if some of the characters were more than one byte long, because
1291        there is a check for at least the minimum number of bytes.
1293    21. Refactored the implementation of \p and \P so as to be more general, to
1294        allow for more different types of property in future. This has changed the
1295        compiled form incompatibly. Anybody with saved compiled patterns that use
1296        \p or \P will have to recompile them.
1298    22. Added "Any" and "L&" to the supported property types.
1300    23. Recognize \x{...} as a code point specifier, even when not in UTF-8 mode,
1301        but give a compile time error if the value is greater than 0xff.
1303    24. The man pages for pcrepartial, pcreprecompile, and pcre_compile2 were
1304        accidentally not being installed or uninstalled.
1306    25. The pcre.h file was built from pcre.h.in, but the only changes that were
1307        made were to insert the current release number. This seemed silly, because
1308        it made things harder for people building PCRE on systems that don't run
1309        "configure". I have turned pcre.h into a distributed file, no longer built
1310        by "configure", with the version identification directly included. There is
1311        no longer a pcre.h.in file.
1313        However, this change necessitated a change to the pcre-config script as
1314        well. It is built from pcre-config.in, and one of the substitutions was the
1315        release number. I have updated configure.ac so that ./configure now finds
1316        the release number by grepping pcre.h.
1318    26. Added the ability to run the tests under valgrind.
1321    Version 6.4 05-Sep-05
1322    ---------------------
1324     1. Change 6.0/10/(l) to pcregrep introduced a bug that caused separator lines
1325        "--" to be printed when multiple files were scanned, even when none of the
1326        -A, -B, or -C options were used. This is not compatible with Gnu grep, so I
1327        consider it to be a bug, and have restored the previous behaviour.
1329     2. A couple of code tidies to get rid of compiler warnings.
1331     3. The pcretest program used to cheat by referring to symbols in the library
1332        whose names begin with _pcre_. These are internal symbols that are not
1333        really supposed to be visible externally, and in some environments it is
1334        possible to suppress them. The cheating is now confined to including
1335        certain files from the library's source, which is a bit cleaner.
1337     4. Renamed pcre.in as pcre.h.in to go with pcrecpp.h.in; it also makes the
1338        file's purpose clearer.
1340     5. Reorganized pcre_ucp_findchar().
1343    Version 6.3 15-Aug-05
1344    ---------------------
1346     1. The file libpcre.pc.in did not have general read permission in the tarball.
1348     2. There were some problems when building without C++ support:
1350        (a) If C++ support was not built, "make install" and "make test" still
1351            tried to test it.
1353        (b) There were problems when the value of CXX was explicitly set. Some
1354            changes have been made to try to fix these, and ...
1356        (c) --disable-cpp can now be used to explicitly disable C++ support.
1358        (d) The use of @CPP_OBJ@ directly caused a blank line preceded by a
1359            backslash in a target when C++ was disabled. This confuses some
1360            versions of "make", apparently. Using an intermediate variable solves
1361            this. (Same for CPP_LOBJ.)
1363     3. $(LINK_FOR_BUILD) now includes $(CFLAGS_FOR_BUILD) and $(LINK)
1364        (non-Windows) now includes $(CFLAGS) because these flags are sometimes
1365        necessary on certain architectures.
1367     4. Added a setting of -export-symbols-regex to the link command to remove
1368        those symbols that are exported in the C sense, but actually are local
1369        within the library, and not documented. Their names all begin with
1370        "_pcre_". This is not a perfect job, because (a) we have to except some
1371        symbols that pcretest ("illegally") uses, and (b) the facility isn't always
1372        available (and never for static libraries). I have made a note to try to
1373        find a way round (a) in the future.
1376    Version 6.2 01-Aug-05
1377    ---------------------
1379     1. There was no test for integer overflow of quantifier values. A construction
1380        such as {1111111111111111} would give undefined results. What is worse, if
1381        a minimum quantifier for a parenthesized subpattern overflowed and became
1382        negative, the calculation of the memory size went wrong. This could have
1383        led to memory overwriting.
1385     2. Building PCRE using VPATH was broken. Hopefully it is now fixed.
1387     3. Added "b" to the 2nd argument of fopen() in dftables.c, for non-Unix-like
1388        operating environments where this matters.
1390     4. Applied Giuseppe Maxia's patch to add additional features for controlling
1391        PCRE options from within the C++ wrapper.
1393     5. Named capturing subpatterns were not being correctly counted when a pattern
1394        was compiled. This caused two problems: (a) If there were more than 100
1395        such subpatterns, the calculation of the memory needed for the whole
1396        compiled pattern went wrong, leading to an overflow error. (b) Numerical
1397        back references of the form \12, where the number was greater than 9, were
1398        not recognized as back references, even though there were sufficient
1399        previous subpatterns.
1401     6. Two minor patches to pcrecpp.cc in order to allow it to compile on older
1402        versions of gcc, e.g. 2.95.4.
1405    Version 6.1 21-Jun-05
1406    ---------------------
1408     1. There was one reference to the variable "posix" in pcretest.c that was not
1409        surrounded by "#if !defined NOPOSIX".
1411     2. Make it possible to compile pcretest without DFA support, UTF8 support, or
1412        the cross-check on the old pcre_info() function, for the benefit of the
1413        cut-down version of PCRE that is currently imported into Exim.
1415     3. A (silly) pattern starting with (?i)(?-i) caused an internal space
1416        allocation error. I've done the easy fix, which wastes 2 bytes for sensible
1417        patterns that start (?i) but I don't think that matters. The use of (?i) is
1418        just an example; this all applies to the other options as well.
1420     4. Since libtool seems to echo the compile commands it is issuing, the output
1421        from "make" can be reduced a bit by putting "@" in front of each libtool
1422        compile command.
1424     5. Patch from the folks at Google for configure.in to be a bit more thorough
1425        in checking for a suitable C++ installation before trying to compile the
1426        C++ stuff. This should fix a reported problem when a compiler was present,
1427        but no suitable headers.
1429     6. The man pages all had just "PCRE" as their title. I have changed them to
1430        be the relevant file name. I have also arranged that these names are
1431        retained in the file doc/pcre.txt, which is a concatenation in text format
1432        of all the man pages except the little individual ones for each function.
1434     7. The NON-UNIX-USE file had not been updated for the different set of source
1435        files that come with release 6. I also added a few comments about the C++
1436        wrapper.
1439    Version 6.0 07-Jun-05
1440    ---------------------
1442     1. Some minor internal re-organization to help with my DFA experiments.
1444     2. Some missing #ifdef SUPPORT_UCP conditionals in pcretest and printint that
1445        didn't matter for the library itself when fully configured, but did matter
1446        when compiling without UCP support, or within Exim, where the ucp files are
1447        not imported.
1449     3. Refactoring of the library code to split up the various functions into
1450        different source modules. The addition of the new DFA matching code (see
1451        below) to a single monolithic source would have made it really too
1452        unwieldy, quite apart from causing all the code to be include in a
1453        statically linked application, when only some functions are used. This is
1454        relevant even without the DFA addition now that patterns can be compiled in
1455        one application and matched in another.
1457        The downside of splitting up is that there have to be some external
1458        functions and data tables that are used internally in different modules of
1459        the library but which are not part of the API. These have all had their
1460        names changed to start with "_pcre_" so that they are unlikely to clash
1461        with other external names.
1463     4. Added an alternate matching function, pcre_dfa_exec(), which matches using
1464        a different (DFA) algorithm. Although it is slower than the original
1465        function, it does have some advantages for certain types of matching
1466        problem.
1468     5. Upgrades to pcretest in order to test the features of pcre_dfa_exec(),
1469        including restarting after a partial match.
1471     6. A patch for pcregrep that defines INVALID_FILE_ATTRIBUTES if it is not
1472        defined when compiling for Windows was sent to me. I have put it into the
1473        code, though I have no means of testing or verifying it.
1475     7. Added the pcre_refcount() auxiliary function.
1477     8. Added the PCRE_FIRSTLINE option. This constrains an unanchored pattern to
1478        match before or at the first newline in the subject string. In pcretest,
1479        the /f option on a pattern can be used to set this.
1481     9. A repeated \w when used in UTF-8 mode with characters greater than 256
1482        would behave wrongly. This has been present in PCRE since release 4.0.
1484    10. A number of changes to the pcregrep command:
1486        (a) Refactored how -x works; insert ^(...)$ instead of setting
1487            PCRE_ANCHORED and checking the length, in preparation for adding
1488            something similar for -w.
1490        (b) Added the -w (match as a word) option.
1492        (c) Refactored the way lines are read and buffered so as to have more
1493            than one at a time available.
1495        (d) Implemented a pcregrep test script.
1497        (e) Added the -M (multiline match) option. This allows patterns to match
1498            over several lines of the subject. The buffering ensures that at least
1499            8K, or the rest of the document (whichever is the shorter) is available
1500            for matching (and similarly the previous 8K for lookbehind assertions).
1502        (f) Changed the --help output so that it now says
1504              -w, --word-regex(p)
1506            instead of two lines, one with "regex" and the other with "regexp"
1507            because that confused at least one person since the short forms are the
1508            same. (This required a bit of code, as the output is generated
1509            automatically from a table. It wasn't just a text change.)
1511        (g) -- can be used to terminate pcregrep options if the next thing isn't an
1512            option but starts with a hyphen. Could be a pattern or a path name
1513            starting with a hyphen, for instance.
1515        (h) "-" can be given as a file name to represent stdin.
1517        (i) When file names are being printed, "(standard input)" is used for
1518            the standard input, for compatibility with GNU grep. Previously
1519            "<stdin>" was used.
1521        (j) The option --label=xxx can be used to supply a name to be used for
1522            stdin when file names are being printed. There is no short form.
1524        (k) Re-factored the options decoding logic because we are going to add
1525            two more options that take data. Such options can now be given in four
1526            different ways, e.g. "-fname", "-f name", "--file=name", "--file name".
1528        (l) Added the -A, -B, and -C options for requesting that lines of context
1529            around matches be printed.
1531        (m) Added the -L option to print the names of files that do not contain
1532            any matching lines, that is, the complement of -l.
1534        (n) The return code is 2 if any file cannot be opened, but pcregrep does
1535            continue to scan other files.
1537        (o) The -s option was incorrectly implemented. For compatibility with other
1538            greps, it now suppresses the error message for a non-existent or non-
1539            accessible file (but not the return code). There is a new option called
1540            -q that suppresses the output of matching lines, which was what -s was
1541            previously doing.
1543        (p) Added --include and --exclude options to specify files for inclusion
1544            and exclusion when recursing.
1546    11. The Makefile was not using the Autoconf-supported LDFLAGS macro properly.
1547        Hopefully, it now does.
1549    12. Missing cast in pcre_study().
1551    13. Added an "uninstall" target to the makefile.
1553    14. Replaced "extern" in the function prototypes in Makefile.in with
1554        "PCRE_DATA_SCOPE", which defaults to 'extern' or 'extern "C"' in the Unix
1555        world, but is set differently for Windows.
1557    15. Added a second compiling function called pcre_compile2(). The only
1558        difference is that it has an extra argument, which is a pointer to an
1559        integer error code. When there is a compile-time failure, this is set
1560        non-zero, in addition to the error test pointer being set to point to an
1561        error message. The new argument may be NULL if no error number is required
1562        (but then you may as well call pcre_compile(), which is now just a
1563        wrapper). This facility is provided because some applications need a
1564        numeric error indication, but it has also enabled me to tidy up the way
1565        compile-time errors are handled in the POSIX wrapper.
1567    16. Added VPATH=.libs to the makefile; this should help when building with one
1568        prefix path and installing with another. (Or so I'm told by someone who
1569        knows more about this stuff than I do.)
1571    17. Added a new option, REG_DOTALL, to the POSIX function regcomp(). This
1572        passes PCRE_DOTALL to the pcre_compile() function, making the "." character
1573        match everything, including newlines. This is not POSIX-compatible, but
1574        somebody wanted the feature. From pcretest it can be activated by using
1575        both the P and the s flags.
1577    18. AC_PROG_LIBTOOL appeared twice in Makefile.in. Removed one.
1579    19. libpcre.pc was being incorrectly installed as executable.
1581    20. A couple of places in pcretest check for end-of-line by looking for '\n';
1582        it now also looks for '\r' so that it will work unmodified on Windows.
1584    21. Added Google's contributed C++ wrapper to the distribution.
1586    22. Added some untidy missing memory free() calls in pcretest, to keep
1587        Electric Fence happy when testing.
1591    Version 5.0 13-Sep-04
1592    ---------------------
1594     1. Internal change: literal characters are no longer packed up into items
1595        containing multiple characters in a single byte-string. Each character
1596        is now matched using a separate opcode. However, there may be more than one
1597        byte in the character in UTF-8 mode.
1599     2. The pcre_callout_block structure has two new fields: pattern_position and
1600        next_item_length. These contain the offset in the pattern to the next match
1601        item, and its length, respectively.
1603     3. The PCRE_AUTO_CALLOUT option for pcre_compile() requests the automatic
1604        insertion of callouts before each pattern item. Added the /C option to
1605        pcretest to make use of this.
1607     4. On the advice of a Windows user, the lines
1609          #if defined(_WIN32) || defined(WIN32)
1610          _setmode( _fileno( stdout ), 0x8000 );
1611          #endif  /* defined(_WIN32) || defined(WIN32) */
1613        have been added to the source of pcretest. This apparently does useful
1614        magic in relation to line terminators.
1616     5. Changed "r" and "w" in the calls to fopen() in pcretest to "rb" and "wb"
1617        for the benefit of those environments where the "b" makes a difference.
1619     6. The icc compiler has the same options as gcc, but "configure" doesn't seem
1620        to know about it. I have put a hack into configure.in that adds in code
1621        to set GCC=yes if CC=icc. This seems to end up at a point in the
1622        generated configure script that is early enough to affect the setting of
1623        compiler options, which is what is needed, but I have no means of testing
1624        whether it really works. (The user who reported this had patched the
1625        generated configure script, which of course I cannot do.)
1627        LATER: After change 22 below (new libtool files), the configure script
1628        seems to know about icc (and also ecc). Therefore, I have commented out
1629        this hack in configure.in.
1631     7. Added support for pkg-config (2 patches were sent in).
1633     8. Negated POSIX character classes that used a combination of internal tables
1634        were completely broken. These were [[:^alpha:]], [[:^alnum:]], and
1635        [[:^ascii]]. Typically, they would match almost any characters. The other
1636        POSIX classes were not broken in this way.
1638     9. Matching the pattern "\b.*?" against "ab cd", starting at offset 1, failed
1639        to find the match, as PCRE was deluded into thinking that the match had to
1640        start at the start point or following a newline. The same bug applied to
1641        patterns with negative forward assertions or any backward assertions
1642        preceding ".*" at the start, unless the pattern required a fixed first
1643        character. This was a failing pattern: "(?!.bcd).*". The bug is now fixed.
1645    10. In UTF-8 mode, when moving forwards in the subject after a failed match
1646        starting at the last subject character, bytes beyond the end of the subject
1647        string were read.
1649    11. Renamed the variable "class" as "classbits" to make life easier for C++
1650        users. (Previously there was a macro definition, but it apparently wasn't
1651        enough.)
1653    12. Added the new field "tables" to the extra data so that tables can be passed
1654        in at exec time, or the internal tables can be re-selected. This allows
1655        a compiled regex to be saved and re-used at a later time by a different
1656        program that might have everything at different addresses.
1658    13. Modified the pcre-config script so that, when run on Solaris, it shows a
1659        -R library as well as a -L library.
1661    14. The debugging options of pcretest (-d on the command line or D on a
1662        pattern) showed incorrect output for anything following an extended class
1663        that contained multibyte characters and which was followed by a quantifier.
1665    15. Added optional support for general category Unicode character properties
1666        via the \p, \P, and \X escapes. Unicode property support implies UTF-8
1667        support. It adds about 90K to the size of the library. The meanings of the
1668        inbuilt class escapes such as \d and \s have NOT been changed.
1670    16. Updated pcredemo.c to include calls to free() to release the memory for the
1671        compiled pattern.
1673    17. The generated file chartables.c was being created in the source directory
1674        instead of in the building directory. This caused the build to fail if the
1675        source directory was different from the building directory, and was
1676        read-only.
1678    18. Added some sample Win commands from Mark Tetrode into the NON-UNIX-USE
1679        file. No doubt somebody will tell me if they don't make sense... Also added
1680        Dan Mooney's comments about building on OpenVMS.
1682    19. Added support for partial matching via the PCRE_PARTIAL option for
1683        pcre_exec() and the \P data escape in pcretest.
1685    20. Extended pcretest with 3 new pattern features:
1687        (i)   A pattern option of the form ">rest-of-line" causes pcretest to
1688              write the compiled pattern to the file whose name is "rest-of-line".
1689              This is a straight binary dump of the data, with the saved pointer to
1690              the character tables forced to be NULL. The study data, if any, is
1691              written too. After writing, pcretest reads a new pattern.
1693        (ii)  If, instead of a pattern, "<rest-of-line" is given, pcretest reads a
1694              compiled pattern from the given file. There must not be any
1695              occurrences of "<" in the file name (pretty unlikely); if there are,
1696              pcretest will instead treat the initial "<" as a pattern delimiter.
1697              After reading in the pattern, pcretest goes on to read data lines as
1698              usual.
1700        (iii) The F pattern option causes pcretest to flip the bytes in the 32-bit
1701              and 16-bit fields in a compiled pattern, to simulate a pattern that
1702              was compiled on a host of opposite endianness.
1704    21. The pcre-exec() function can now cope with patterns that were compiled on
1705        hosts of opposite endianness, with this restriction:
1707          As for any compiled expression that is saved and used later, the tables
1708          pointer field cannot be preserved; the extra_data field in the arguments
1709          to pcre_exec() should be used to pass in a tables address if a value
1710          other than the default internal tables were used at compile time.
1712    22. Calling pcre_exec() with a negative value of the "ovecsize" parameter is
1713        now diagnosed as an error. Previously, most of the time, a negative number
1714        would have been treated as zero, but if in addition "ovector" was passed as
1715        NULL, a crash could occur.
1717    23. Updated the files ltmain.sh, config.sub, config.guess, and aclocal.m4 with
1718        new versions from the libtool 1.5 distribution (the last one is a copy of
1719        a file called libtool.m4). This seems to have fixed the need to patch
1720        "configure" to support Darwin 1.3 (which I used to do). However, I still
1721        had to patch ltmain.sh to ensure that ${SED} is set (it isn't on my
1722        workstation).
1724    24. Changed the PCRE licence to be the more standard "BSD" licence.
1727    Version 4.5 01-Dec-03
1728    ---------------------
1730     1. There has been some re-arrangement of the code for the match() function so
1731        that it can be compiled in a version that does not call itself recursively.
1732        Instead, it keeps those local variables that need separate instances for
1733        each "recursion" in a frame on the heap, and gets/frees frames whenever it
1734        needs to "recurse". Keeping track of where control must go is done by means
1735        of setjmp/longjmp. The whole thing is implemented by a set of macros that
1736        hide most of the details from the main code, and operates only if
1737        NO_RECURSE is defined while compiling pcre.c. If PCRE is built using the
1738        "configure" mechanism, "--disable-stack-for-recursion" turns on this way of
1739        operating.
1741        To make it easier for callers to provide specially tailored get/free
1742        functions for this usage, two new functions, pcre_stack_malloc, and
1743        pcre_stack_free, are used. They are always called in strict stacking order,
1744        and the size of block requested is always the same.
1746        The PCRE_CONFIG_STACKRECURSE info parameter can be used to find out whether
1747        PCRE has been compiled to use the stack or the heap for recursion. The
1748        -C option of pcretest uses this to show which version is compiled.
1750        A new data escape \S, is added to pcretest; it causes the amounts of store
1751        obtained and freed by both kinds of malloc/free at match time to be added
1752        to the output.
1754     2. Changed the locale test to use "fr_FR" instead of "fr" because that's
1755        what's available on my current Linux desktop machine.
1757     3. When matching a UTF-8 string, the test for a valid string at the start has
1758        been extended. If start_offset is not zero, PCRE now checks that it points
1759        to a byte that is the start of a UTF-8 character. If not, it returns
1760        PCRE_ERROR_BADUTF8_OFFSET (-11). Note: the whole string is still checked;
1761        this is necessary because there may be backward assertions in the pattern.
1762        When matching the same subject several times, it may save resources to use
1763        PCRE_NO_UTF8_CHECK on all but the first call if the string is long.
1765     4. The code for checking the validity of UTF-8 strings has been tightened so
1766        that it rejects (a) strings containing 0xfe or 0xff bytes and (b) strings
1767        containing "overlong sequences".
1769     5. Fixed a bug (appearing twice) that I could not find any way of exploiting!
1770        I had written "if ((digitab[*p++] && chtab_digit) == 0)" where the "&&"
1771        should have been "&", but it just so happened that all the cases this let
1772        through by mistake were picked up later in the function.
1774     6. I had used a variable called "isblank" - this is a C99 function, causing
1775        some compilers to warn. To avoid this, I renamed it (as "blankclass").
1777     7. Cosmetic: (a) only output another newline at the end of pcretest if it is
1778        prompting; (b) run "./pcretest /dev/null" at the start of the test script
1779        so the version is shown; (c) stop "make test" echoing "./RunTest".
1781     8. Added patches from David Burgess to enable PCRE to run on EBCDIC systems.
1783     9. The prototype for memmove() for systems that don't have it was using
1784        size_t, but the inclusion of the header that defines size_t was later. I've
1785        moved the #includes for the C headers earlier to avoid this.
1787    10. Added some adjustments to the code to make it easier to compiler on certain
1788        special systems:
1790          (a) Some "const" qualifiers were missing.
1791          (b) Added the macro EXPORT before all exported functions; by default this
1792              is defined to be empty.
1793          (c) Changed the dftables auxiliary program (that builds chartables.c) so
1794              that it reads its output file name as an argument instead of writing
1795              to the standard output and assuming this can be redirected.
1797    11. In UTF-8 mode, if a recursive reference (e.g. (?1)) followed a character
1798        class containing characters with values greater than 255, PCRE compilation
1799        went into a loop.
1801    12. A recursive reference to a subpattern that was within another subpattern
1802        that had a minimum quantifier of zero caused PCRE to crash. For example,
1803        (x(y(?2))z)? provoked this bug with a subject that got as far as the
1804        recursion. If the recursively-called subpattern itself had a zero repeat,
1805        that was OK.
1807    13. In pcretest, the buffer for reading a data line was set at 30K, but the
1808        buffer into which it was copied (for escape processing) was still set at
1809        1024, so long lines caused crashes.
1811    14. A pattern such as /[ab]{1,3}+/ failed to compile, giving the error
1812        "internal error: code overflow...". This applied to any character class
1813        that was followed by a possessive quantifier.
1815    15. Modified the Makefile to add libpcre.la as a prerequisite for
1816        libpcreposix.la because I was told this is needed for a parallel build to
1817        work.
1819    16. If a pattern that contained .* following optional items at the start was
1820        studied, the wrong optimizing data was generated, leading to matching
1821        errors. For example, studying /[ab]*.*c/ concluded, erroneously, that any
1822        matching string must start with a or b or c. The correct conclusion for
1823        this pattern is that a match can start with any character.
1826    Version 4.4 13-Aug-03
1827    ---------------------
1829     1. In UTF-8 mode, a character class containing characters with values between
1830        127 and 255 was not handled correctly if the compiled pattern was studied.
1831        In fixing this, I have also improved the studying algorithm for such
1832        classes (slightly).
1834     2. Three internal functions had redundant arguments passed to them. Removal
1835        might give a very teeny performance improvement.
1837     3. Documentation bug: the value of the capture_top field in a callout is *one
1838        more than* the number of the hightest numbered captured substring.
1840     4. The Makefile linked pcretest and pcregrep with -lpcre, which could result
1841        in incorrectly linking with a previously installed version. They now link
1842        explicitly with libpcre.la.
1844     5. configure.in no longer needs to recognize Cygwin specially.
1846     6. A problem in pcre.in for Windows platforms is fixed.
1848     7. If a pattern was successfully studied, and the -d (or /D) flag was given to
1849        pcretest, it used to include the size of the study block as part of its
1850        output. Unfortunately, the structure contains a field that has a different
1851        size on different hardware architectures. This meant that the tests that
1852        showed this size failed. As the block is currently always of a fixed size,
1853        this information isn't actually particularly useful in pcretest output, so
1854        I have just removed it.
1856     8. Three pre-processor statements accidentally did not start in column 1.
1857        Sadly, there are *still* compilers around that complain, even though
1858        standard C has not required this for well over a decade. Sigh.
1860     9. In pcretest, the code for checking callouts passed small integers in the
1861        callout_data field, which is a void * field. However, some picky compilers
1862        complained about the casts involved for this on 64-bit systems. Now
1863        pcretest passes the address of the small integer instead, which should get
1864        rid of the warnings.
1866    10. By default, when in UTF-8 mode, PCRE now checks for valid UTF-8 strings at
1867        both compile and run time, and gives an error if an invalid UTF-8 sequence
1868        is found. There is a option for disabling this check in cases where the
1869        string is known to be correct and/or the maximum performance is wanted.
1871    11. In response to a bug report, I changed one line in Makefile.in from
1873            -Wl,--out-implib,.libs/lib@WIN_PREFIX@pcreposix.dll.a \
1874        to
1875            -Wl,--out-implib,.libs/@WIN_PREFIX@libpcreposix.dll.a \
1877        to look similar to other lines, but I have no way of telling whether this
1878        is the right thing to do, as I do not use Windows. No doubt I'll get told
1879        if it's wrong...
1882    Version 4.3 21-May-03
1883    ---------------------
1885    1. Two instances of @WIN_PREFIX@ omitted from the Windows targets in the
1886       Makefile.
1888    2. Some refactoring to improve the quality of the code:
1890       (i)   The utf8_table... variables are now declared "const".
1892       (ii)  The code for \cx, which used the "case flipping" table to upper case
1893             lower case letters, now just substracts 32. This is ASCII-specific,
1894             but the whole concept of \cx is ASCII-specific, so it seems
1895             reasonable.
1897       (iii) PCRE was using its character types table to recognize decimal and
1898             hexadecimal digits in the pattern. This is silly, because it handles
1899             only 0-9, a-f, and A-F, but the character types table is locale-
1900             specific, which means strange things might happen. A private
1901             table is now used for this - though it costs 256 bytes, a table is
1902             much faster than multiple explicit tests. Of course, the standard
1903             character types table is still used for matching digits in subject
1904             strings against \d.
1906       (iv)  Strictly, the identifier ESC_t is reserved by POSIX (all identifiers
1907             ending in _t are). So I've renamed it as ESC_tee.
1909    3. The first argument for regexec() in the POSIX wrapper should have been
1910       defined as "const".
1912    4. Changed pcretest to use malloc() for its buffers so that they can be
1913       Electric Fenced for debugging.
1915    5. There were several places in the code where, in UTF-8 mode, PCRE would try
1916       to read one or more bytes before the start of the subject string. Often this
1917       had no effect on PCRE's behaviour, but in some circumstances it could
1918       provoke a segmentation fault.
1920    6. A lookbehind at the start of a pattern in UTF-8 mode could also cause PCRE
1921       to try to read one or more bytes before the start of the subject string.
1923    7. A lookbehind in a pattern matched in non-UTF-8 mode on a PCRE compiled with
1924       UTF-8 support could misbehave in various ways if the subject string
1925       contained bytes with the 0x80 bit set and the 0x40 bit unset in a lookbehind
1926       area. (PCRE was not checking for the UTF-8 mode flag, and trying to move
1927       back over UTF-8 characters.)
1930    Version 4.2 14-Apr-03
1931    ---------------------
1933    1. Typo "#if SUPPORT_UTF8" instead of "#ifdef SUPPORT_UTF8" fixed.
1935    2. Changes to the building process, supplied by Ronald Landheer-Cieslak
1936         [ON_WINDOWS]: new variable, "#" on non-Windows platforms
1937         [NOT_ON_WINDOWS]: new variable, "#" on Windows platforms
1938         [WIN_PREFIX]: new variable, "cyg" for Cygwin
1939         * Makefile.in: use autoconf substitution for OBJEXT, EXEEXT, BUILD_OBJEXT
1940           and BUILD_EXEEXT
1941         Note: automatic setting of the BUILD variables is not yet working
1942         set CPPFLAGS and BUILD_CPPFLAGS (but don't use yet) - should be used at
1943           compile-time but not at link-time
1944         [LINK]: use for linking executables only
1945         make different versions for Windows and non-Windows
1946         [LINKLIB]: new variable, copy of UNIX-style LINK, used for linking
1947           libraries
1948         [LINK_FOR_BUILD]: new variable
1949         [OBJEXT]: use throughout
1950         [EXEEXT]: use throughout
1951         <winshared>: new target
1952         <wininstall>: new target
1953         <dftables.o>: use native compiler
1954         <dftables>: use native linker
1955         <install>: handle Windows platform correctly
1956         <clean>: ditto
1957         <check>: ditto
1958         copy DLL to top builddir before testing
1960       As part of these changes, -no-undefined was removed again. This was reported
1961       to give trouble on HP-UX 11.0, so getting rid of it seems like a good idea
1962       in any case.
1964    3. Some tidies to get rid of compiler warnings:
1966       . In the match_data structure, match_limit was an unsigned long int, whereas
1967         match_call_count was an int. I've made them both unsigned long ints.
1969       . In pcretest the fact that a const uschar * doesn't automatically cast to
1970         a void * provoked a warning.
1972       . Turning on some more compiler warnings threw up some "shadow" variables
1973         and a few more missing casts.
1975    4. If PCRE was complied with UTF-8 support, but called without the PCRE_UTF8
1976       option, a class that contained a single character with a value between 128
1977       and 255 (e.g. /[\xFF]/) caused PCRE to crash.
1979    5. If PCRE was compiled with UTF-8 support, but called without the PCRE_UTF8
1980       option, a class that contained several characters, but with at least one
1981       whose value was between 128 and 255 caused PCRE to crash.
1984    Version 4.1 12-Mar-03
1985    ---------------------
1987    1. Compiling with gcc -pedantic found a couple of places where casts were
1988    needed, and a string in dftables.c that was longer than standard compilers are
1989    required to support.
1991    2. Compiling with Sun's compiler found a few more places where the code could
1992    be tidied up in order to avoid warnings.
1994    3. The variables for cross-compiling were called HOST_CC and HOST_CFLAGS; the
1995    first of these names is deprecated in the latest Autoconf in favour of the name
1996    CC_FOR_BUILD, because "host" is typically used to mean the system on which the
1997    compiled code will be run. I can't find a reference for HOST_CFLAGS, but by
1998    analogy I have changed it to CFLAGS_FOR_BUILD.
2000    4. Added -no-undefined to the linking command in the Makefile, because this is
2001    apparently helpful for Windows. To make it work, also added "-L. -lpcre" to the
2002    linking step for the pcreposix library.
2004    5. PCRE was failing to diagnose the case of two named groups with the same
2005    name.
2007    6. A problem with one of PCRE's optimizations was discovered. PCRE remembers a
2008    literal character that is needed in the subject for a match, and scans along to
2009    ensure that it is present before embarking on the full matching process. This
2010    saves time in cases of nested unlimited repeats that are never going to match.
2011    Problem: the scan can take a lot of time if the subject is very long (e.g.
2012    megabytes), thus penalizing straightforward matches. It is now done only if the
2013    amount of subject to be scanned is less than 1000 bytes.
2015    7. A lesser problem with the same optimization is that it was recording the
2016    first character of an anchored pattern as "needed", thus provoking a search
2017    right along the subject, even when the first match of the pattern was going to
2018    fail. The "needed" character is now not set for anchored patterns, unless it
2019    follows something in the pattern that is of non-fixed length. Thus, it still
2020    fulfils its original purpose of finding quick non-matches in cases of nested
2021    unlimited repeats, but isn't used for simple anchored patterns such as /^abc/.
2024    Version 4.0 17-Feb-03
2025    ---------------------
2027    1. If a comment in an extended regex that started immediately after a meta-item
2028    extended to the end of string, PCRE compiled incorrect data. This could lead to
2029    all kinds of weird effects. Example: /#/ was bad; /()#/ was bad; /a#/ was not.
2031    2. Moved to autoconf 2.53 and libtool 1.4.2.
2033    3. Perl 5.8 no longer needs "use utf8" for doing UTF-8 things. Consequently,
2034    the special perltest8 script is no longer needed - all the tests can be run
2035    from a single perltest script.
2037    4. From 5.004, Perl has not included the VT character (0x0b) in the set defined
2038    by \s. It has now been removed in PCRE. This means it isn't recognized as
2039    whitespace in /x regexes too, which is the same as Perl. Note that the POSIX
2040    class [:space:] *does* include VT, thereby creating a mess.
2042    5. Added the class [:blank:] (a GNU extension from Perl 5.8) to match only
2043    space and tab.
2045    6. Perl 5.005 was a long time ago. It's time to amalgamate the tests that use
2046    its new features into the main test script, reducing the number of scripts.
2048    7. Perl 5.8 has changed the meaning of patterns like /a(?i)b/. Earlier versions
2049    were backward compatible, and made the (?i) apply to the whole pattern, as if
2050    /i were given. Now it behaves more logically, and applies the option setting
2051    only to what follows. PCRE has been changed to follow suit. However, if it
2052    finds options settings right at the start of the pattern, it extracts them into
2053    the global options, as before. Thus, they show up in the info data.
2055    8. Added support for the \Q...\E escape sequence. Characters in between are
2056    treated as literals. This is slightly different from Perl in that $ and @ are
2057    also handled as literals inside the quotes. In Perl, they will cause variable
2058    interpolation. Note the following examples:
2060        Pattern            PCRE matches      Perl matches
2062        \Qabc$xyz\E        abc$xyz           abc followed by the contents of $xyz
2063        \Qabc\$xyz\E       abc\$xyz          abc\$xyz
2064        \Qabc\E\$\Qxyz\E   abc$xyz           abc$xyz
2066    For compatibility with Perl, \Q...\E sequences are recognized inside character
2067    classes as well as outside them.
2069    9. Re-organized 3 code statements in pcretest to avoid "overflow in
2070    floating-point constant arithmetic" warnings from a Microsoft compiler. Added a
2071    (size_t) cast to one statement in pcretest and one in pcreposix to avoid
2072    signed/unsigned warnings.
2074    10. SunOS4 doesn't have strtoul(). This was used only for unpicking the -o
2075    option for pcretest, so I've replaced it by a simple function that does just
2076    that job.
2078    11. pcregrep was ending with code 0 instead of 2 for the commands "pcregrep" or
2079    "pcregrep -".
2081    12. Added "possessive quantifiers" ?+, *+, ++, and {,}+ which come from Sun's
2082    Java package. This provides some syntactic sugar for simple cases of what my
2083    documentation calls "once-only subpatterns". A pattern such as x*+ is the same
2084    as (?>x*). In other words, if what is inside (?>...) is just a single repeated
2085    item, you can use this simplified notation. Note that only makes sense with
2086    greedy quantifiers. Consequently, the use of the possessive quantifier forces
2087    greediness, whatever the setting of the PCRE_UNGREEDY option.
2089    13. A change of greediness default within a pattern was not taking effect at
2090    the current level for patterns like /(b+(?U)a+)/. It did apply to parenthesized
2091    subpatterns that followed. Patterns like /b+(?U)a+/ worked because the option
2092    was abstracted outside.
2094    14. PCRE now supports the \G assertion. It is true when the current matching
2095    position is at the start point of the match. This differs from \A when the
2096    starting offset is non-zero. Used with the /g option of pcretest (or similar
2097    code), it works in the same way as it does for Perl's /g option. If all
2098    alternatives of a regex begin with \G, the expression is anchored to the start
2099    match position, and the "anchored" flag is set in the compiled expression.
2101    15. Some bugs concerning the handling of certain option changes within patterns
2102    have been fixed. These applied to options other than (?ims). For example,
2103    "a(?x: b c )d" did not match "XabcdY" but did match "Xa b c dY". It should have
2104    been the other way round. Some of this was related to change 7 above.
2106    16. PCRE now gives errors for /[.x.]/ and /[=x=]/ as unsupported POSIX
2107    features, as Perl does. Previously, PCRE gave the warnings only for /[[.x.]]/
2108    and /[[=x=]]/. PCRE now also gives an error for /[:name:]/ because it supports
2109    POSIX classes only within a class (e.g. /[[:alpha:]]/).
2111    17. Added support for Perl's \C escape. This matches one byte, even in UTF8
2112    mode. Unlike ".", it always matches newline, whatever the setting of
2113    PCRE_DOTALL. However, PCRE does not permit \C to appear in lookbehind
2114    assertions. Perl allows it, but it doesn't (in general) work because it can't
2115    calculate the length of the lookbehind. At least, that's the case for Perl
2116    5.8.0 - I've been told they are going to document that it doesn't work in
2117    future.
2119    18. Added an error diagnosis for escapes that PCRE does not support: these are
2120    \L, \l, \N, \P, \p, \U, \u, and \X.
2122    19. Although correctly diagnosing a missing ']' in a character class, PCRE was
2123    reading past the end of the pattern in cases such as /[abcd/.
2125    20. PCRE was getting more memory than necessary for patterns with classes that
2126    contained both POSIX named classes and other characters, e.g. /[[:space:]abc/.
2128    21. Added some code, conditional on #ifdef VPCOMPAT, to make life easier for
2129    compiling PCRE for use with Virtual Pascal.
2131    22. Small fix to the Makefile to make it work properly if the build is done
2132    outside the source tree.
2134    23. Added a new extension: a condition to go with recursion. If a conditional
2135    subpattern starts with (?(R) the "true" branch is used if recursion has
2136    happened, whereas the "false" branch is used only at the top level.
2138    24. When there was a very long string of literal characters (over 255 bytes
2139    without UTF support, over 250 bytes with UTF support), the computation of how
2140    much memory was required could be incorrect, leading to segfaults or other
2141    strange effects.
2143    25. PCRE was incorrectly assuming anchoring (either to start of subject or to
2144    start of line for a non-DOTALL pattern) when a pattern started with (.*) and
2145    there was a subsequent back reference to those brackets. This meant that, for
2146    example, /(.*)\d+\1/ failed to match "abc123bc". Unfortunately, it isn't
2147    possible to check for precisely this case. All we can do is abandon the
2148    optimization if .* occurs inside capturing brackets when there are any back
2149    references whatsoever. (See below for a better fix that came later.)
2151    26. The handling of the optimization for finding the first character of a
2152    non-anchored pattern, and for finding a character that is required later in the
2153    match were failing in some cases. This didn't break the matching; it just
2154    failed to optimize when it could. The way this is done has been re-implemented.
2156    27. Fixed typo in error message for invalid (?R item (it said "(?p").
2158    28. Added a new feature that provides some of the functionality that Perl
2159    provides with (?{...}). The facility is termed a "callout". The way it is done
2160    in PCRE is for the caller to provide an optional function, by setting
2161    pcre_callout to its entry point. Like pcre_malloc and pcre_free, this is a
2162    global variable. By default it is unset, which disables all calling out. To get
2163    the function called, the regex must include (?C) at appropriate points. This
2164    is, in fact, equivalent to (?C0), and any number <= 255 may be given with (?C).
2165    This provides a means of identifying different callout points. When PCRE
2166    reaches such a point in the regex, if pcre_callout has been set, the external
2167    function is called. It is provided with data in a structure called
2168    pcre_callout_block, which is defined in pcre.h. If the function returns 0,
2169    matching continues; if it returns a non-zero value, the match at the current
2170    point fails. However, backtracking will occur if possible. [This was changed
2171    later and other features added - see item 49 below.]
2173    29. pcretest is upgraded to test the callout functionality. It provides a
2174    callout function that displays information. By default, it shows the start of
2175    the match and the current position in the text. There are some new data escapes
2176    to vary what happens:
2178        \C+         in addition, show current contents of captured substrings
2179        \C-         do not supply a callout function
2180        \C!n        return 1 when callout number n is reached
2181        \C!n!m      return 1 when callout number n is reached for the mth time
2183    30. If pcregrep was called with the -l option and just a single file name, it
2184    output "<stdin>" if a match was found, instead of the file name.
2186    31. Improve the efficiency of the POSIX API to PCRE. If the number of capturing
2187    slots is less than POSIX_MALLOC_THRESHOLD, use a block on the stack to pass to
2188    pcre_exec(). This saves a malloc/free per call. The default value of
2189    POSIX_MALLOC_THRESHOLD is 10; it can be changed by --with-posix-malloc-threshold
2190    when configuring.
2192    32. The default maximum size of a compiled pattern is 64K. There have been a
2193    few cases of people hitting this limit. The code now uses macros to handle the
2194    storing of links as offsets within the compiled pattern. It defaults to 2-byte
2195    links, but this can be changed to 3 or 4 bytes by --with-link-size when
2196    configuring. Tests 2 and 5 work only with 2-byte links because they output
2197    debugging information about compiled patterns.
2199    33. Internal code re-arrangements:
2201    (a) Moved the debugging function for printing out a compiled regex into
2202        its own source file (printint.c) and used #include to pull it into
2203        pcretest.c and, when DEBUG is defined, into pcre.c, instead of having two
2204        separate copies.
2206    (b) Defined the list of op-code names for debugging as a macro in
2207        internal.h so that it is next to the definition of the opcodes.
2209    (c) Defined a table of op-code lengths for simpler skipping along compiled
2210        code. This is again a macro in internal.h so that it is next to the
2211        definition of the opcodes.
2213    34. Added support for recursive calls to individual subpatterns, along the
2214    lines of Robin Houston's patch (but implemented somewhat differently).
2216    35. Further mods to the Makefile to help Win32. Also, added code to pcregrep to
2217    allow it to read and process whole directories in Win32. This code was
2218    contributed by Lionel Fourquaux; it has not been tested by me.
2220    36. Added support for named subpatterns. The Python syntax (?P<name>...) is
2221    used to name a group. Names consist of alphanumerics and underscores, and must
2222    be unique. Back references use the syntax (?P=name) and recursive calls use
2223    (?P>name) which is a PCRE extension to the Python extension. Groups still have
2224    numbers. The function pcre_fullinfo() can be used after compilation to extract
2225    a name/number map. There are three relevant calls:
2227      PCRE_INFO_NAMEENTRYSIZE        yields the size of each entry in the map
2228      PCRE_INFO_NAMECOUNT            yields the number of entries
2229      PCRE_INFO_NAMETABLE            yields a pointer to the map.
2231    The map is a vector of fixed-size entries. The size of each entry depends on
2232    the length of the longest name used. The first two bytes of each entry are the
2233    group number, most significant byte first. There follows the corresponding
2234    name, zero terminated. The names are in alphabetical order.
2236    37. Make the maximum literal string in the compiled code 250 for the non-UTF-8
2237    case instead of 255. Making it the same both with and without UTF-8 support
2238    means that the same test output works with both.
2240    38. There was a case of malloc(0) in the POSIX testing code in pcretest. Avoid
2241    calling malloc() with a zero argument.
2243    39. Change 25 above had to resort to a heavy-handed test for the .* anchoring
2244    optimization. I've improved things by keeping a bitmap of backreferences with
2245    numbers 1-31 so that if .* occurs inside capturing brackets that are not in
2246    fact referenced, the optimization can be applied. It is unlikely that a
2247    relevant occurrence of .* (i.e. one which might indicate anchoring or forcing
2248    the match to follow \n) will appear inside brackets with a number greater than
2249    31, but if it does, any back reference > 31 suppresses the optimization.
2251    40. Added a new compile-time option PCRE_NO_AUTO_CAPTURE. This has the effect
2252    of disabling numbered capturing parentheses. Any opening parenthesis that is
2253    not followed by ? behaves as if it were followed by ?: but named parentheses
2254    can still be used for capturing (and they will acquire numbers in the usual
2255    way).
2257    41. Redesigned the return codes from the match() function into yes/no/error so
2258    that errors can be passed back from deep inside the nested calls. A malloc
2259    failure while inside a recursive subpattern call now causes the
2260    PCRE_ERROR_NOMEMORY return instead of quietly going wrong.
2262    42. It is now possible to set a limit on the number of times the match()
2263    function is called in a call to pcre_exec(). This facility makes it possible to
2264    limit the amount of recursion and backtracking, though not in a directly
2265    obvious way, because the match() function is used in a number of different
2266    circumstances. The count starts from zero for each position in the subject
2267    string (for non-anchored patterns). The default limit is, for compatibility, a
2268    large number, namely 10 000 000. You can change this in two ways:
2270    (a) When configuring PCRE before making, you can use --with-match-limit=n
2271        to set a default value for the compiled library.
2273    (b) For each call to pcre_exec(), you can pass a pcre_extra block in which
2274        a different value is set. See 45 below.
2276    If the limit is exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT.
2278    43. Added a new function pcre_config(int, void *) to enable run-time extraction
2279    of things that can be changed at compile time. The first argument specifies
2280    what is wanted and the second points to where the information is to be placed.
2281    The current list of available information is:
2283      PCRE_CONFIG_UTF8
2285    The output is an integer that is set to one if UTF-8 support is available;
2286    otherwise it is set to zero.
2290    The output is an integer that it set to the value of the code that is used for
2291    newline. It is either LF (10) or CR (13).
2295    The output is an integer that contains the number of bytes used for internal
2296    linkage in compiled expressions. The value is 2, 3, or 4. See item 32 above.
2300    The output is an integer that contains the threshold above which the POSIX
2301    interface uses malloc() for output vectors. See item 31 above.
2305    The output is an unsigned integer that contains the default limit of the number
2306    of match() calls in a pcre_exec() execution. See 42 above.
2308    44. pcretest has been upgraded by the addition of the -C option. This causes it
2309    to extract all the available output from the new pcre_config() function, and to
2310    output it. The program then exits immediately.
2312    45. A need has arisen to pass over additional data with calls to pcre_exec() in
2313    order to support additional features. One way would have been to define
2314    pcre_exec2() (for example) with extra arguments, but this would not have been
2315    extensible, and would also have required all calls to the original function to
2316    be mapped to the new one. Instead, I have chosen to extend the mechanism that
2317    is used for passing in "extra" data from pcre_study().
2319    The pcre_extra structure is now exposed and defined in pcre.h. It currently
2320    contains the following fields:
2322      flags         a bitmap indicating which of the following fields are set
2323      study_data    opaque data from pcre_study()
2324      match_limit   a way of specifying a limit on match() calls for a specific
2325                      call to pcre_exec()
2326      callout_data  data for callouts (see 49 below)
2328    The flag bits are also defined in pcre.h, and are
2334    The pcre_study() function now returns one of these new pcre_extra blocks, with
2335    the actual study data pointed to by the study_data field, and the
2336    PCRE_EXTRA_STUDY_DATA flag set. This can be passed directly to pcre_exec() as
2337    before. That is, this change is entirely upwards-compatible and requires no
2338    change to existing code.
2340    If you want to pass in additional data to pcre_exec(), you can either place it
2341    in a pcre_extra block provided by pcre_study(), or create your own pcre_extra
2342    block.
2344    46. pcretest has been extended to test the PCRE_EXTRA_MATCH_LIMIT feature. If a
2345    data string contains the escape sequence \M, pcretest calls pcre_exec() several
2346    times with different match limits, until it finds the minimum value needed for
2347    pcre_exec() to complete. The value is then output. This can be instructive; for
2348    most simple matches the number is quite small, but for pathological cases it
2349    gets very large very quickly.
2351    47. There's a new option for pcre_fullinfo() called PCRE_INFO_STUDYSIZE. It
2352    returns the size of the data block pointed to by the study_data field in a
2353    pcre_extra block, that is, the value that was passed as the argument to
2354    pcre_malloc() when PCRE was getting memory in which to place the information
2355    created by pcre_study(). The fourth argument should point to a size_t variable.
2356    pcretest has been extended so that this information is shown after a successful
2357    pcre_study() call when information about the compiled regex is being displayed.
2359    48. Cosmetic change to Makefile: there's no need to have / after $(DESTDIR)
2360    because what follows is always an absolute path. (Later: it turns out that this
2361    is more than cosmetic for MinGW, because it doesn't like empty path
2362    components.)
2364    49. Some changes have been made to the callout feature (see 28 above):
2366    (i)  A callout function now has three choices for what it returns:
2368           0  =>  success, carry on matching
2369         > 0  =>  failure at this point, but backtrack if possible
2370         < 0  =>  serious error, return this value from pcre_exec()
2372         Negative values should normally be chosen from the set of PCRE_ERROR_xxx
2373         values. In particular, returning PCRE_ERROR_NOMATCH forces a standard
2374         "match failed" error. The error number PCRE_ERROR_CALLOUT is reserved for
2375         use by callout functions. It will never be used by PCRE itself.
2377    (ii) The pcre_extra structure (see 45 above) has a void * field called
2378         callout_data, with corresponding flag bit PCRE_EXTRA_CALLOUT_DATA. The
2379         pcre_callout_block structure has a field of the same name. The contents of
2380         the field passed in the pcre_extra structure are passed to the callout
2381         function in the corresponding field in the callout block. This makes it
2382         easier to use the same callout-containing regex from multiple threads. For
2383         testing, the pcretest program has a new data escape
2385           \C*n        pass the number n (may be negative) as callout_data
2387         If the callout function in pcretest receives a non-zero value as
2388         callout_data, it returns that value.
2390    50. Makefile wasn't handling CFLAGS properly when compiling dftables. Also,
2391    there were some redundant $(CFLAGS) in commands that are now specified as
2392    $(LINK), which already includes $(CFLAGS).
2394    51. Extensions to UTF-8 support are listed below. These all apply when (a) PCRE
2395    has been compiled with UTF-8 support *and* pcre_compile() has been compiled
2396    with the PCRE_UTF8 flag. Patterns that are compiled without that flag assume
2397    one-byte characters throughout. Note that case-insensitive matching applies
2398    only to characters whose values are less than 256. PCRE doesn't support the
2399    notion of cases for higher-valued characters.
2401    (i)   A character class whose characters are all within 0-255 is handled as
2402          a bit map, and the map is inverted for negative classes. Previously, a
2403          character > 255 always failed to match such a class; however it should
2404          match if the class was a negative one (e.g. [^ab]). This has been fixed.
2406    (ii)  A negated character class with a single character < 255 is coded as
2407          "not this character" (OP_NOT). This wasn't working properly when the test
2408          character was multibyte, either singly or repeated.
2410    (iii) Repeats of multibyte characters are now handled correctly in UTF-8
2411          mode, for example: \x{100}{2,3}.
2413    (iv)  The character escapes \b, \B, \d, \D, \s, \S, \w, and \W (either
2414          singly or repeated) now correctly test multibyte characters. However,
2415          PCRE doesn't recognize any characters with values greater than 255 as
2416          digits, spaces, or word characters. Such characters always match \D, \S,
2417          and \W, and never match \d, \s, or \w.
2419    (v)   Classes may now contain characters and character ranges with values
2420          greater than 255. For example: [ab\x{100}-\x{400}].
2422    (vi)  pcregrep now has a --utf-8 option (synonym -u) which makes it call
2423          PCRE in UTF-8 mode.
2425    52. The info request value PCRE_INFO_FIRSTCHAR has been renamed
2426    PCRE_INFO_FIRSTBYTE because it is a byte value. However, the old name is
2427    retained for backwards compatibility. (Note that LASTLITERAL is also a byte
2428    value.)
2430    53. The single man page has become too large. I have therefore split it up into
2431    a number of separate man pages. These also give rise to individual HTML pages;
2432    these are now put in a separate directory, and there is an index.html page that
2433    lists them all. Some hyperlinking between the pages has been installed.
2435    54. Added convenience functions for handling named capturing parentheses.
2437    55. Unknown escapes inside character classes (e.g. [\M]) and escapes that
2438    aren't interpreted therein (e.g. [\C]) are literals in Perl. This is now also
2439    true in PCRE, except when the PCRE_EXTENDED option is set, in which case they
2440    are faulted.
2442    56. Introduced HOST_CC and HOST_CFLAGS which can be set in the environment when
2443    calling configure. These values are used when compiling the dftables.c program
2444    which is run to generate the source of the default character tables. They
2445    default to the values of CC and CFLAGS. If you are cross-compiling PCRE,
2446    you will need to set these values.
2448    57. Updated the building process for Windows DLL, as provided by Fred Cox.
2451    Version 3.9 02-Jan-02
2452    ---------------------
2454    1. A bit of extraneous text had somehow crept into the pcregrep documentation.
2456    2. If --disable-static was given, the building process failed when trying to
2457    build pcretest and pcregrep. (For some reason it was using libtool to compile
2458    them, which is not right, as they aren't part of the library.)
2461    Version 3.8 18-Dec-01
2462    ---------------------
2464    1. The experimental UTF-8 code was completely screwed up. It was packing the
2465    bytes in the wrong order. How dumb can you get?
2468    Version 3.7 29-Oct-01
2469    ---------------------
2471    1. In updating pcretest to check change 1 of version 3.6, I screwed up.
2472    This caused pcretest, when used on the test data, to segfault. Unfortunately,
2473    this didn't happen under Solaris 8, where I normally test things.
2475    2. The Makefile had to be changed to make it work on BSD systems, where 'make'
2476    doesn't seem to recognize that ./xxx and xxx are the same file. (This entry
2477    isn't in ChangeLog distributed with 3.7 because I forgot when I hastily made
2478    this fix an hour or so after the initial 3.7 release.)
2481    Version 3.6 23-Oct-01
2482    ---------------------
2484    1. Crashed with /(sens|respons)e and \1ibility/ and "sense and sensibility" if
2485    offsets passed as NULL with zero offset count.
2487    2. The config.guess and config.sub files had not been updated when I moved to
2488    the latest autoconf.
2491    Version 3.5 15-Aug-01
2492    ---------------------
2494    1. Added some missing #if !defined NOPOSIX conditionals in pcretest.c that
2495    had been forgotten.
2497    2. By using declared but undefined structures, we can avoid using "void"
2498    definitions in pcre.h while keeping the internal definitions of the structures
2499    private.
2501    3. The distribution is now built using autoconf 2.50 and libtool 1.4. From a
2502    user point of view, this means that both static and shared libraries are built
2503    by default, but this can be individually controlled. More of the work of
2504    handling this static/shared cases is now inside libtool instead of PCRE's make
2505    file.
2507    4. The pcretest utility is now installed along with pcregrep because it is
2508    useful for users (to test regexs) and by doing this, it automatically gets
2509    relinked by libtool. The documentation has been turned into a man page, so
2510    there are now .1, .txt, and .html versions in /doc.
2512    5. Upgrades to pcregrep:
2513       (i)   Added long-form option names like gnu grep.
2514       (ii)  Added --help to list all options with an explanatory phrase.
2515       (iii) Added -r, --recursive to recurse into sub-directories.
2516       (iv)  Added -f, --file to read patterns from a file.
2518    6. pcre_exec() was referring to its "code" argument before testing that
2519    argument for NULL (and giving an error if it was NULL).
2521    7. Upgraded Makefile.in to allow for compiling in a different directory from
2522    the source directory.
2524    8. Tiny buglet in pcretest: when pcre_fullinfo() was called to retrieve the
2525    options bits, the pointer it was passed was to an int instead of to an unsigned
2526    long int. This mattered only on 64-bit systems.
2528    9. Fixed typo (3.4/1) in pcre.h again. Sigh. I had changed pcre.h (which is
2529    generated) instead of pcre.in, which it its source. Also made the same change
2530    in several of the .c files.
2532    10. A new release of gcc defines printf() as a macro, which broke pcretest
2533    because it had an ifdef in the middle of a string argument for printf(). Fixed
2534    by using separate calls to printf().
2536    11. Added --enable-newline-is-cr and --enable-newline-is-lf to the configure
2537    script, to force use of CR or LF instead of \n in the source. On non-Unix
2538    systems, the value can be set in config.h.
2540    12. The limit of 200 on non-capturing parentheses is a _nesting_ limit, not an
2541    absolute limit. Changed the text of the error message to make this clear, and
2542    likewise updated the man page.
2544    13. The limit of 99 on the number of capturing subpatterns has been removed.
2545    The new limit is 65535, which I hope will not be a "real" limit.
2548  Version 3.4 22-Aug-00  Version 3.4 22-Aug-00
2549  ---------------------  ---------------------

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