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revision 41 by nigel, Sat Feb 24 21:39:17 2007 UTC revision 289 by ph10, Sun Dec 23 12:17:20 2007 UTC
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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
4    Version 7.5 23-Dec-07
5    ---------------------
7  Version 2.09 14-Sep-99  1.  Applied a patch from Craig: "This patch makes it possible to 'ignore'
8  ----------------------      values in parens when parsing an RE using the C++ wrapper."
10    2.  Negative specials like \S did not work in character classes in UTF-8 mode.
11        Characters greater than 255 were excluded from the class instead of being
12        included.
14    3.  The same bug as (2) above applied to negated POSIX classes such as
15        [:^space:].
17    4.  PCRECPP_STATIC was referenced in pcrecpp_internal.h, but nowhere was it
18        defined or documented. It seems to have been a typo for PCRE_STATIC, so
19        I have changed it.
21    5.  The construct (?&) was not diagnosed as a syntax error (it referenced the
22        first named subpattern) and a construct such as (?&a) would reference the
23        first named subpattern whose name started with "a" (in other words, the
24        length check was missing). Both these problems are fixed. "Subpattern name
25        expected" is now given for (?&) (a zero-length name), and this patch also
26        makes it give the same error for \k'' (previously it complained that that
27        was a reference to a non-existent subpattern).
29    6.  The erroneous patterns (?+-a) and (?-+a) give different error messages;
30        this is right because (?- can be followed by option settings as well as by
31        digits. I have, however, made the messages clearer.
33    7.  Patterns such as (?(1)a|b) (a pattern that contains fewer subpatterns
34        than the number used in the conditional) now cause a compile-time error.
35        This is actually not compatible with Perl, which accepts such patterns, but
36        treats the conditional as always being FALSE (as PCRE used to), but it
37        seems to me that giving a diagnostic is better.
39    8.  Change "alphameric" to the more common word "alphanumeric" in comments
40        and messages.
42    9.  Fix two occurrences of "backslash" in comments that should have been
43        "backspace".
45    10. Remove two redundant lines of code that can never be obeyed (their function
46        was moved elsewhere).
48    11. The program that makes PCRE's Unicode character property table had a bug
49        which caused it to generate incorrect table entries for sequences of
50        characters that have the same character type, but are in different scripts.
51        It amalgamated them into a single range, with the script of the first of
52        them. In other words, some characters were in the wrong script. There were
53        thirteen such cases, affecting characters in the following ranges:
55          U+002b0 - U+002c1
56          U+0060c - U+0060d
57          U+0061e - U+00612
58          U+0064b - U+0065e
59          U+0074d - U+0076d
60          U+01800 - U+01805
61          U+01d00 - U+01d77
62          U+01d9b - U+01dbf
63          U+0200b - U+0200f
64          U+030fc - U+030fe
65          U+03260 - U+0327f
66          U+0fb46 - U+0fbb1
67          U+10450 - U+1049d
69    12. The -o option (show only the matching part of a line) for pcregrep was not
70        compatible with GNU grep in that, if there was more than one match in a
71        line, it showed only the first of them. It now behaves in the same way as
72        GNU grep.
74    13. If the -o and -v options were combined for pcregrep, it printed a blank
75        line for every non-matching line. GNU grep prints nothing, and pcregrep now
76        does the same. The return code can be used to tell if there were any
77        non-matching lines.
79    14. Added --file-offsets and --line-offsets to pcregrep.
81    15. The pattern (?=something)(?R) was not being diagnosed as a potentially
82        infinitely looping recursion. The bug was that positive lookaheads were not
83        being skipped when checking for a possible empty match (negative lookaheads
84        and both kinds of lookbehind were skipped).
86    16. Fixed two typos in the Windows-only code in pcregrep.c, and moved the
87        inclusion of <windows.h> to before rather than after the definition of
88        INVALID_FILE_ATTRIBUTES (patch from David Byron).
90    17. Specifying a possessive quantifier with a specific limit for a Unicode
91        character property caused pcre_compile() to compile bad code, which led at
92        runtime to PCRE_ERROR_INTERNAL (-14). Examples of patterns that caused this
93        are: /\p{Zl}{2,3}+/8 and /\p{Cc}{2}+/8. It was the possessive "+" that
94        caused the error; without that there was no problem.
96    18. Added --enable-pcregrep-libz and --enable-pcregrep-libbz2.
98    19. Added --enable-pcretest-libreadline.
100    20. In pcrecpp.cc, the variable 'count' was incremented twice in
101        RE::GlobalReplace(). As a result, the number of replacements returned was
102        double what it should be. I have removed one of the increments.
105    Version 7.4 21-Sep-07
106    ---------------------
108    1.  Change 7.3/28 was implemented for classes by looking at the bitmap. This
109        means that a class such as [\s] counted as "explicit reference to CR or
110        LF". That isn't really right - the whole point of the change was to try to
111        help when there was an actual mention of one of the two characters. So now
112        the change happens only if \r or \n (or a literal CR or LF) character is
113        encountered.
115    2.  The 32-bit options word was also used for 6 internal flags, but the numbers
116        of both had grown to the point where there were only 3 bits left.
117        Fortunately, there was spare space in the data structure, and so I have
118        moved the internal flags into a new 16-bit field to free up more option
119        bits.
121    3.  The appearance of (?J) at the start of a pattern set the DUPNAMES option,
122        but did not set the internal JCHANGED flag - either of these is enough to
123        control the way the "get" function works - but the PCRE_INFO_JCHANGED
124        facility is supposed to tell if (?J) was ever used, so now (?J) at the
125        start sets both bits.
127    4.  Added options (at build time, compile time, exec time) to change \R from
128        matching any Unicode line ending sequence to just matching CR, LF, or CRLF.
130    5.  doc/pcresyntax.html was missing from the distribution.
132    6.  Put back the definition of PCRE_ERROR_NULLWSLIMIT, for backward
133        compatibility, even though it is no longer used.
135    7.  Added macro for snprintf to pcrecpp_unittest.cc and also for strtoll and
136        strtoull to pcrecpp.cc to select the available functions in WIN32 when the
137        windows.h file is present (where different names are used). [This was
138        reversed later after testing - see 16 below.]
140    8.  Changed all #include <config.h> to #include "config.h". There were also
141        some further <pcre.h> cases that I changed to "pcre.h".
143    9.  When pcregrep was used with the --colour option, it missed the line ending
144        sequence off the lines that it output.
146    10. It was pointed out to me that arrays of string pointers cause lots of
147        relocations when a shared library is dynamically loaded. A technique of
148        using a single long string with a table of offsets can drastically reduce
149        these. I have refactored PCRE in four places to do this. The result is
150        dramatic:
152          Originally:                          290
153          After changing UCP table:            187
154          After changing error message table:   43
155          After changing table of "verbs"       36
156          After changing table of Posix names   22
158        Thanks to the folks working on Gregex for glib for this insight.
160    11. --disable-stack-for-recursion caused compiling to fail unless -enable-
161        unicode-properties was also set.
163    12. Updated the tests so that they work when \R is defaulted to ANYCRLF.
165    13. Added checks for ANY and ANYCRLF to pcrecpp.cc where it previously
166        checked only for CRLF.
168    14. Added casts to pcretest.c to avoid compiler warnings.
170    15. Added Craig's patch to various pcrecpp modules to avoid compiler warnings.
172    16. Added Craig's patch to remove the WINDOWS_H tests, that were not working,
173        and instead check for _strtoi64 explicitly, and avoid the use of snprintf()
174        entirely. This removes changes made in 7 above.
176    17. The CMake files have been updated, and there is now more information about
177        building with CMake in the NON-UNIX-USE document.
180    Version 7.3 28-Aug-07
181    ---------------------
183     1. In the rejigging of the build system that eventually resulted in 7.1, the
184        line "#include <pcre.h>" was included in pcre_internal.h. The use of angle
185        brackets there is not right, since it causes compilers to look for an
186        installed pcre.h, not the version that is in the source that is being
187        compiled (which of course may be different). I have changed it back to:
189          #include "pcre.h"
191        I have a vague recollection that the change was concerned with compiling in
192        different directories, but in the new build system, that is taken care of
193        by the VPATH setting the Makefile.
195     2. The pattern .*$ when run in not-DOTALL UTF-8 mode with newline=any failed
196        when the subject happened to end in the byte 0x85 (e.g. if the last
197        character was \x{1ec5}). *Character* 0x85 is one of the "any" newline
198        characters but of course it shouldn't be taken as a newline when it is part
199        of another character. The bug was that, for an unlimited repeat of . in
200        not-DOTALL UTF-8 mode, PCRE was advancing by bytes rather than by
201        characters when looking for a newline.
203     3. A small performance improvement in the DOTALL UTF-8 mode .* case.
205     4. Debugging: adjusted the names of opcodes for different kinds of parentheses
206        in debug output.
208     5. Arrange to use "%I64d" instead of "%lld" and "%I64u" instead of "%llu" for
209        long printing in the pcrecpp unittest when running under MinGW.
211     6. ESC_K was left out of the EBCDIC table.
213     7. Change 7.0/38 introduced a new limit on the number of nested non-capturing
214        parentheses; I made it 1000, which seemed large enough. Unfortunately, the
215        limit also applies to "virtual nesting" when a pattern is recursive, and in
216        this case 1000 isn't so big. I have been able to remove this limit at the
217        expense of backing off one optimization in certain circumstances. Normally,
218        when pcre_exec() would call its internal match() function recursively and
219        immediately return the result unconditionally, it uses a "tail recursion"
220        feature to save stack. However, when a subpattern that can match an empty
221        string has an unlimited repetition quantifier, it no longer makes this
222        optimization. That gives it a stack frame in which to save the data for
223        checking that an empty string has been matched. Previously this was taken
224        from the 1000-entry workspace that had been reserved. So now there is no
225        explicit limit, but more stack is used.
227     8. Applied Daniel's patches to solve problems with the import/export magic
228        syntax that is required for Windows, and which was going wrong for the
229        pcreposix and pcrecpp parts of the library. These were overlooked when this
230        problem was solved for the main library.
232     9. There were some crude static tests to avoid integer overflow when computing
233        the size of patterns that contain repeated groups with explicit upper
234        limits. As the maximum quantifier is 65535, the maximum group length was
235        set at 30,000 so that the product of these two numbers did not overflow a
236        32-bit integer. However, it turns out that people want to use groups that
237        are longer than 30,000 bytes (though not repeat them that many times).
238        Change 7.0/17 (the refactoring of the way the pattern size is computed) has
239        made it possible to implement the integer overflow checks in a much more
240        dynamic way, which I have now done. The artificial limitation on group
241        length has been removed - we now have only the limit on the total length of
242        the compiled pattern, which depends on the LINK_SIZE setting.
244    10. Fixed a bug in the documentation for get/copy named substring when
245        duplicate names are permitted. If none of the named substrings are set, the
246        functions return PCRE_ERROR_NOSUBSTRING (7); the doc said they returned an
247        empty string.
249    11. Because Perl interprets \Q...\E at a high level, and ignores orphan \E
250        instances, patterns such as [\Q\E] or [\E] or even [^\E] cause an error,
251        because the ] is interpreted as the first data character and the
252        terminating ] is not found. PCRE has been made compatible with Perl in this
253        regard. Previously, it interpreted [\Q\E] as an empty class, and [\E] could
254        cause memory overwriting.
256    10. Like Perl, PCRE automatically breaks an unlimited repeat after an empty
257        string has been matched (to stop an infinite loop). It was not recognizing
258        a conditional subpattern that could match an empty string if that
259        subpattern was within another subpattern. For example, it looped when
260        trying to match  (((?(1)X|))*)  but it was OK with  ((?(1)X|)*)  where the
261        condition was not nested. This bug has been fixed.
263    12. A pattern like \X?\d or \P{L}?\d in non-UTF-8 mode could cause a backtrack
264        past the start of the subject in the presence of bytes with the top bit
265        set, for example "\x8aBCD".
267    13. Added Perl 5.10 experimental backtracking controls (*FAIL), (*F), (*PRUNE),
268        (*SKIP), (*THEN), (*COMMIT), and (*ACCEPT).
270    14. Optimized (?!) to (*FAIL).
272    15. Updated the test for a valid UTF-8 string to conform to the later RFC 3629.
273        This restricts code points to be within the range 0 to 0x10FFFF, excluding
274        the "low surrogate" sequence 0xD800 to 0xDFFF. Previously, PCRE allowed the
275        full range 0 to 0x7FFFFFFF, as defined by RFC 2279. Internally, it still
276        does: it's just the validity check that is more restrictive.
278    16. Inserted checks for integer overflows during escape sequence (backslash)
279        processing, and also fixed erroneous offset values for syntax errors during
280        backslash processing.
282    17. Fixed another case of looking too far back in non-UTF-8 mode (cf 12 above)
283        for patterns like [\PPP\x8a]{1,}\x80 with the subject "A\x80".
285    18. An unterminated class in a pattern like (?1)\c[ with a "forward reference"
286        caused an overrun.
288    19. A pattern like (?:[\PPa*]*){8,} which had an "extended class" (one with
289        something other than just ASCII characters) inside a group that had an
290        unlimited repeat caused a loop at compile time (while checking to see
291        whether the group could match an empty string).
293    20. Debugging a pattern containing \p or \P could cause a crash. For example,
294        [\P{Any}] did so. (Error in the code for printing property names.)
296    21. An orphan \E inside a character class could cause a crash.
298    22. A repeated capturing bracket such as (A)? could cause a wild memory
299        reference during compilation.
301    23. There are several functions in pcre_compile() that scan along a compiled
302        expression for various reasons (e.g. to see if it's fixed length for look
303        behind). There were bugs in these functions when a repeated \p or \P was
304        present in the pattern. These operators have additional parameters compared
305        with \d, etc, and these were not being taken into account when moving along
306        the compiled data. Specifically:
308        (a) A item such as \p{Yi}{3} in a lookbehind was not treated as fixed
309            length.
311        (b) An item such as \pL+ within a repeated group could cause crashes or
312            loops.
314        (c) A pattern such as \p{Yi}+(\P{Yi}+)(?1) could give an incorrect
315            "reference to non-existent subpattern" error.
317        (d) A pattern like (\P{Yi}{2}\277)? could loop at compile time.
319    24. A repeated \S or \W in UTF-8 mode could give wrong answers when multibyte
320        characters were involved (for example /\S{2}/8g with "A\x{a3}BC").
322    25. Using pcregrep in multiline, inverted mode (-Mv) caused it to loop.
324    26. Patterns such as [\P{Yi}A] which include \p or \P and just one other
325        character were causing crashes (broken optimization).
327    27. Patterns such as (\P{Yi}*\277)* (group with possible zero repeat containing
328        \p or \P) caused a compile-time loop.
330    28. More problems have arisen in unanchored patterns when CRLF is a valid line
331        break. For example, the unstudied pattern [\r\n]A does not match the string
332        "\r\nA" because change 7.0/46 below moves the current point on by two
333        characters after failing to match at the start. However, the pattern \nA
334        *does* match, because it doesn't start till \n, and if [\r\n]A is studied,
335        the same is true. There doesn't seem any very clean way out of this, but
336        what I have chosen to do makes the common cases work: PCRE now takes note
337        of whether there can be an explicit match for \r or \n anywhere in the
338        pattern, and if so, 7.0/46 no longer applies. As part of this change,
339        there's a new PCRE_INFO_HASCRORLF option for finding out whether a compiled
340        pattern has explicit CR or LF references.
342    29. Added (*CR) etc for changing newline setting at start of pattern.
345    Version 7.2 19-Jun-07
346    ---------------------
348     1. If the fr_FR locale cannot be found for test 3, try the "french" locale,
349        which is apparently normally available under Windows.
351     2. Re-jig the pcregrep tests with different newline settings in an attempt
352        to make them independent of the local environment's newline setting.
354     3. Add code to configure.ac to remove -g from the CFLAGS default settings.
356     4. Some of the "internals" tests were previously cut out when the link size
357        was not 2, because the output contained actual offsets. The recent new
358        "Z" feature of pcretest means that these can be cut out, making the tests
359        usable with all link sizes.
361     5. Implemented Stan Switzer's goto replacement for longjmp() when not using
362        stack recursion. This gives a massive performance boost under BSD, but just
363        a small improvement under Linux. However, it saves one field in the frame
364        in all cases.
366     6. Added more features from the forthcoming Perl 5.10:
368        (a) (?-n) (where n is a string of digits) is a relative subroutine or
369            recursion call. It refers to the nth most recently opened parentheses.
371        (b) (?+n) is also a relative subroutine call; it refers to the nth next
372            to be opened parentheses.
374        (c) Conditions that refer to capturing parentheses can be specified
375            relatively, for example, (?(-2)... or (?(+3)...
377        (d) \K resets the start of the current match so that everything before
378            is not part of it.
380        (e) \k{name} is synonymous with \k<name> and \k'name' (.NET compatible).
382        (f) \g{name} is another synonym - part of Perl 5.10's unification of
383            reference syntax.
385        (g) (?| introduces a group in which the numbering of parentheses in each
386            alternative starts with the same number.
388        (h) \h, \H, \v, and \V match horizontal and vertical whitespace.
390     7. Added two new calls to pcre_fullinfo(): PCRE_INFO_OKPARTIAL and
393     8. A pattern such as  (.*(.)?)*  caused pcre_exec() to fail by either not
394        terminating or by crashing. Diagnosed by Viktor Griph; it was in the code
395        for detecting groups that can match an empty string.
397     9. A pattern with a very large number of alternatives (more than several
398        hundred) was running out of internal workspace during the pre-compile
399        phase, where pcre_compile() figures out how much memory will be needed. A
400        bit of new cunning has reduced the workspace needed for groups with
401        alternatives. The 1000-alternative test pattern now uses 12 bytes of
402        workspace instead of running out of the 4096 that are available.
404    10. Inserted some missing (unsigned int) casts to get rid of compiler warnings.
406    11. Applied patch from Google to remove an optimization that didn't quite work.
407        The report of the bug said:
409          pcrecpp::RE("a*").FullMatch("aaa") matches, while
410          pcrecpp::RE("a*?").FullMatch("aaa") does not, and
411          pcrecpp::RE("a*?\\z").FullMatch("aaa") does again.
413    12. If \p or \P was used in non-UTF-8 mode on a character greater than 127
414        it matched the wrong number of bytes.
417    Version 7.1 24-Apr-07
418    ---------------------
420     1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
421        that is more "standard", making use of automake and other Autotools. There
422        is some re-arrangement of the files and adjustment of comments consequent
423        on this.
425     2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
426        for recursive directory scanning broke on some systems because the files
427        are not scanned in any specific order and on different systems the order
428        was different. A call to "sort" has been inserted into RunGrepTest for the
429        approprate test as a short-term fix. In the longer term there may be an
430        alternative.
432     3. I had an email from Eric Raymond about problems translating some of PCRE's
433        man pages to HTML (despite the fact that I distribute HTML pages, some
434        people do their own conversions for various reasons). The problems
435        concerned the use of low-level troff macros .br and .in. I have therefore
436        removed all such uses from the man pages (some were redundant, some could
437        be replaced by .nf/.fi pairs). The 132html script that I use to generate
438        HTML has been updated to handle .nf/.fi and to complain if it encounters
439        .br or .in.
441     4. Updated comments in configure.ac that get placed in config.h.in and also
442        arranged for config.h to be included in the distribution, with the name
443        config.h.generic, for the benefit of those who have to compile without
444        Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
446     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
447        Weber: (1) pcre_internal.h was missing some function renames; (2) updated
448        makevp.bat for the current PCRE, using the additional files
449        makevp_c.txt, makevp_l.txt, and pcregexp.pas.
451     6. A Windows user reported a minor discrepancy with test 2, which turned out
452        to be caused by a trailing space on an input line that had got lost in his
453        copy. The trailing space was an accident, so I've just removed it.
455     7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
456        that is needed.
458     8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
459        as "const" (a) because they are and (b) because it helps the PHP
460        maintainers who have recently made a script to detect big data structures
461        in the php code that should be moved to the .rodata section. I remembered
462        to update Builducptable as well, so it won't revert if ucptable.h is ever
463        re-created.
465     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
466        pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
467        order to be able to cut out the UTF-8 tables in the latter when UTF-8
468        support is not required. This saves 1.5-2K of code, which is important in
469        some applications.
471        Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
472        so as not to refer to the tables, even though these functions will never be
473        called when UTF-8 support is disabled. Otherwise there are problems with a
474        shared library.
476    10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
478        (a) It was defining its arguments as char * instead of void *.
480        (b) It was assuming that all moves were upwards in memory; this was true
481            a long time ago when I wrote it, but is no longer the case.
483        The emulated memove() is provided for those environments that have neither
484        memmove() nor bcopy(). I didn't think anyone used it these days, but that
485        is clearly not the case, as these two bugs were recently reported.
487    11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
488        and Detrail to create the HTML documentation, the .txt form of the man
489        pages, and it removes trailing spaces from listed files. It also creates
490        pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
491        case, it wraps all the #defines with #ifndefs. This script should be run
492        before "make dist".
494    12. Fixed two fairly obscure bugs concerned with quantified caseless matching
495        with Unicode property support.
497        (a) For a maximizing quantifier, if the two different cases of the
498            character were of different lengths in their UTF-8 codings (there are
499            some cases like this - I found 11), and the matching function had to
500            back up over a mixture of the two cases, it incorrectly assumed they
501            were both the same length.
503        (b) When PCRE was configured to use the heap rather than the stack for
504            recursion during matching, it was not correctly preserving the data for
505            the other case of a UTF-8 character when checking ahead for a match
506            while processing a minimizing repeat. If the check also involved
507            matching a wide character, but failed, corruption could cause an
508            erroneous result when trying to check for a repeat of the original
509            character.
511    13. Some tidying changes to the testing mechanism:
513        (a) The RunTest script now detects the internal link size and whether there
514            is UTF-8 and UCP support by running ./pcretest -C instead of relying on
515            values substituted by "configure". (The RunGrepTest script already did
516            this for UTF-8.) The configure.ac script no longer substitutes the
517            relevant variables.
519        (b) The debugging options /B and /D in pcretest show the compiled bytecode
520            with length and offset values. This means that the output is different
521            for different internal link sizes. Test 2 is skipped for link sizes
522            other than 2 because of this, bypassing the problem. Unfortunately,
523            there was also a test in test 3 (the locale tests) that used /B and
524            failed for link sizes other than 2. Rather than cut the whole test out,
525            I have added a new /Z option to pcretest that replaces the length and
526            offset values with spaces. This is now used to make test 3 independent
527            of link size. (Test 2 will be tidied up later.)
529    14. If erroroffset was passed as NULL to pcre_compile, it provoked a
530        segmentation fault instead of returning the appropriate error message.
532    15. In multiline mode when the newline sequence was set to "any", the pattern
533        ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
534        This doesn't seem right; it now treats the CRLF combination as the line
535        ending, and so does not match in that case. It's only a pattern such as ^$
536        that would hit this one: something like ^ABC$ would have failed after \r
537        and then tried again after \r\n.
539    16. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
540        in an attempt to make files that differ only in their line terminators
541        compare equal. This works on Linux.
543    17. Under certain error circumstances pcregrep might try to free random memory
544        as it exited. This is now fixed, thanks to valgrind.
546    19. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
547        "abc\r\n\r\n", it found an unwanted second match after the second \r. This
548        was because its rules for how to advance for /g after matching an empty
549        string at the end of a line did not allow for this case. They now check for
550        it specially.
552    20. pcretest is supposed to handle patterns and data of any length, by
553        extending its buffers when necessary. It was getting this wrong when the
554        buffer for a data line had to be extended.
556    21. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or
557        CRLF as a newline sequence.
559    22. Code for handling Unicode properties in pcre_dfa_exec() wasn't being cut
560        out by #ifdef SUPPORT_UCP. This did no harm, as it could never be used, but
561        I have nevertheless tidied it up.
563    23. Added some casts to kill warnings from HP-UX ia64 compiler.
565    24. Added a man page for pcre-config.
568    Version 7.0 19-Dec-06
569    ---------------------
571     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
572        moving to gcc 4.1.1.
574     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
575        sys/time.h, which is documented as needed for this function. It doesn't
576        seem to matter on Linux, but it showed up on some releases of OS X.
578     3. It seems that there are systems where bytes whose values are greater than
579        127 match isprint() in the "C" locale. The "C" locale should be the
580        default when a C program starts up. In most systems, only ASCII printing
581        characters match isprint(). This difference caused the output from pcretest
582        to vary, making some of the tests fail. I have changed pcretest so that:
584        (a) When it is outputting text in the compiled version of a pattern, bytes
585            other than 32-126 are always shown as hex escapes.
587        (b) When it is outputting text that is a matched part of a subject string,
588            it does the same, unless a different locale has been set for the match
589            (using the /L modifier). In this case, it uses isprint() to decide.
591     4. Fixed a major bug that caused incorrect computation of the amount of memory
592        required for a compiled pattern when options that changed within the
593        pattern affected the logic of the preliminary scan that determines the
594        length. The relevant options are -x, and -i in UTF-8 mode. The result was
595        that the computed length was too small. The symptoms of this bug were
596        either the PCRE error "internal error: code overflow" from pcre_compile(),
597        or a glibc crash with a message such as "pcretest: free(): invalid next
598        size (fast)". Examples of patterns that provoked this bug (shown in
599        pcretest format) are:
601          /(?-x: )/x
602          /(?x)(?-x: \s*#\s*)/
603          /((?i)[\x{c0}])/8
604          /(?i:[\x{c0}])/8
606        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
607        is now done differently.
609     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
610        wrapper classes; (b) implement a new function in the C++ scanner that is
611        more efficient than the old way of doing things because it avoids levels of
612        recursion in the regex matching; (c) add a paragraph to the documentation
613        for the FullMatch() function.
615     6. The escape sequence \n was being treated as whatever was defined as
616        "newline". Not only was this contrary to the documentation, which states
617        that \n is character 10 (hex 0A), but it also went horribly wrong when
618        "newline" was defined as CRLF. This has been fixed.
620     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
621        was being set to -1 for the "end of line" case (supposedly a value that no
622        character can have). Though this value is never used (the check for end of
623        line is "zero bytes in current character"), it caused compiler complaints.
624        I've changed it to 0xffffffff.
626     8. In pcre_version.c, the version string was being built by a sequence of
627        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
628        string (as it is for production releases) called a macro with an empty
629        argument. The C standard says the result of this is undefined. The gcc
630        compiler treats it as an empty string (which was what was wanted) but it is
631        reported that Visual C gives an error. The source has been hacked around to
632        avoid this problem.
634     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
635        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
636        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
637        of them did).
639    10. Originally, pcretest opened its input and output without "b"; then I was
640        told that "b" was needed in some environments, so it was added for release
641        5.0 to both the input and output. (It makes no difference on Unix-like
642        systems.) Later I was told that it is wrong for the input on Windows. I've
643        now abstracted the modes into two macros, to make it easier to fiddle with
644        them, and removed "b" from the input mode under Windows.
646    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
648    12. Added -help and --help to pcretest as an official way of being reminded
649        of the options.
651    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
652        and pcrecpp.cc because they annoy compilers at high warning levels.
654    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
656    15. Fixed an occurrence of == in configure.ac that should have been = (shell
657        scripts are not C programs :-) and which was not noticed because it works
658        on Linux.
660    16. pcretest is supposed to handle any length of pattern and data line (as one
661        line or as a continued sequence of lines) by extending its input buffer if
662        necessary. This feature was broken for very long pattern lines, leading to
663        a string of junk being passed to pcre_compile() if the pattern was longer
664        than about 50K.
666    17. I have done a major re-factoring of the way pcre_compile() computes the
667        amount of memory needed for a compiled pattern. Previously, there was code
668        that made a preliminary scan of the pattern in order to do this. That was
669        OK when PCRE was new, but as the facilities have expanded, it has become
670        harder and harder to keep it in step with the real compile phase, and there
671        have been a number of bugs (see for example, 4 above). I have now found a
672        cunning way of running the real compile function in a "fake" mode that
673        enables it to compute how much memory it would need, while actually only
674        ever using a few hundred bytes of working memory and without too many
675        tests of the mode. This should make future maintenance and development
676        easier. A side effect of this work is that the limit of 200 on the nesting
677        depth of parentheses has been removed (though this was never a serious
678        limitation, I suspect). However, there is a downside: pcre_compile() now
679        runs more slowly than before (30% or more, depending on the pattern). I
680        hope this isn't a big issue. There is no effect on runtime performance.
682    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
683        newline (only possible for the last line of a file) and it was a
684        pattern that set a locale (followed by /Lsomething), pcretest crashed.
686    19. Added additional timing features to pcretest. (1) The -tm option now times
687        matching only, not compiling. (2) Both -t and -tm can be followed, as a
688        separate command line item, by a number that specifies the number of
689        repeats to use when timing. The default is 50000; this gives better
690        precision, but takes uncomfortably long for very large patterns.
692    20. Extended pcre_study() to be more clever in cases where a branch of a
693        subpattern has no definite first character. For example, (a*|b*)[cd] would
694        previously give no result from pcre_study(). Now it recognizes that the
695        first character must be a, b, c, or d.
697    21. There was an incorrect error "recursive call could loop indefinitely" if
698        a subpattern (or the entire pattern) that was being tested for matching an
699        empty string contained only one non-empty item after a nested subpattern.
700        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
701        incorrectly, because the \d was being skipped in the check.
703    22. The pcretest program now has a new pattern option /B and a command line
704        option -b, which is equivalent to adding /B to every pattern. This causes
705        it to show the compiled bytecode, without the additional information that
706        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
707        is the same as /B/I).
709    23. A new optimization is now able automatically to treat some sequences such
710        as a*b as a*+b. More specifically, if something simple (such as a character
711        or a simple class like \d) has an unlimited quantifier, and is followed by
712        something that cannot possibly match the quantified thing, the quantifier
713        is automatically "possessified".
715    24. A recursive reference to a subpattern whose number was greater than 39
716        went wrong under certain circumstances in UTF-8 mode. This bug could also
717        have affected the operation of pcre_study().
719    25. Realized that a little bit of performance could be had by replacing
720        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
722    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
724    27. Possessive quantifiers such as a++ were previously implemented by turning
725        them into atomic groups such as ($>a+). Now they have their own opcodes,
726        which improves performance. This includes the automatically created ones
727        from 23 above.
729    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
730        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
731        the first matched character to be a colon. This applied both to named and
732        numbered groups.
734    29. The ucpinternal.h header file was missing its idempotency #ifdef.
736    30. I was sent a "project" file called libpcre.a.dev which I understand makes
737        building PCRE on Windows easier, so I have included it in the distribution.
739    31. There is now a check in pcretest against a ridiculously large number being
740        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
741        loop, the loop is abandoned.
743    32. Forward references to subpatterns in conditions such as (?(2)...) where
744        subpattern 2 is defined later cause pcre_compile() to search forwards in
745        the pattern for the relevant set of parentheses. This search went wrong
746        when there were unescaped parentheses in a character class, parentheses
747        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
749    33. "Subroutine" calls and backreferences were previously restricted to
750        referencing subpatterns earlier in the regex. This restriction has now
751        been removed.
753    34. Added a number of extra features that are going to be in Perl 5.10. On the
754        whole, these are just syntactic alternatives for features that PCRE had
755        previously implemented using the Python syntax or my own invention. The
756        other formats are all retained for compatibility.
758        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
759            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
760            also .NET compatible.
762        (b) A recursion or subroutine call to a named group can now be defined as
763            (?&name) as well as (?P>name).
765        (c) A backreference to a named group can now be defined as \k<name> or
766            \k'name' as well as (?P=name). The new forms, as well as being in Perl
767            5.10, are also .NET compatible.
769        (d) A conditional reference to a named group can now use the syntax
770            (?(<name>) or (?('name') as well as (?(name).
772        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
773            groups (named and numbered) that are never evaluated inline, but can be
774            called as "subroutines" from elsewhere. In effect, the DEFINE condition
775            is always false. There may be only one alternative in such a group.
777        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
778            as the simple (?(R). The condition is true only if the most recent
779            recursion is that of the given number or name. It does not search out
780            through the entire recursion stack.
782        (g) The escape \gN or \g{N} has been added, where N is a positive or
783            negative number, specifying an absolute or relative reference.
785    35. Tidied to get rid of some further signed/unsigned compiler warnings and
786        some "unreachable code" warnings.
788    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
789        things, this adds five new scripts.
791    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
792        There were also incompatibilities regarding the handling of \Q..\E inside
793        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
794        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
796    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
797        matches an empty string, and forcibly breaks the loop. There were bugs in
798        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
799        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
800        separate and independent bugs (that affected different cases) have been
801        fixed.
803    39. Refactored the code to abolish the use of different opcodes for small
804        capturing bracket numbers. This is a tidy that I avoided doing when I
805        removed the limit on the number of capturing brackets for 3.5 back in 2001.
806        The new approach is not only tidier, it makes it possible to reduce the
807        memory needed to fix the previous bug (38).
809    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
810        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
811        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
812        mode.
814    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
815        report.
817    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
818        copy construction and assignment in the C++ wrapper.
820    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
821        couple of bugs that could have given wrong results in the "--newline=crlf"
822        case.
824    44. Added a number of casts and did some reorganization of signed/unsigned int
825        variables following suggestions from Dair Grant. Also renamed the variable
826        "this" as "item" because it is a C++ keyword.
828    45. Arranged for dftables to add
830          #include "pcre_internal.h"
832        to pcre_chartables.c because without it, gcc 4.x may remove the array
833        definition from the final binary if PCRE is built into a static library and
834        dead code stripping is activated.
836    46. For an unanchored pattern, if a match attempt fails at the start of a
837        newline sequence, and the newline setting is CRLF or ANY, and the next two
838        characters are CRLF, advance by two characters instead of one.
841    Version 6.7 04-Jul-06
842    ---------------------
844     1. In order to handle tests when input lines are enormously long, pcretest has
845        been re-factored so that it automatically extends its buffers when
846        necessary. The code is crude, but this _is_ just a test program. The
847        default size has been increased from 32K to 50K.
849     2. The code in pcre_study() was using the value of the re argument before
850        testing it for NULL. (Of course, in any sensible call of the function, it
851        won't be NULL.)
853     3. The memmove() emulation function in pcre_internal.h, which is used on
854        systems that lack both memmove() and bcopy() - that is, hardly ever -
855        was missing a "static" storage class specifier.
857     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
858        containing an extended class (one that cannot be represented by a bitmap
859        because it contains high-valued characters or Unicode property items, e.g.
860        [\pZ]). Almost always one would set UTF-8 mode when processing such a
861        pattern, but PCRE should not loop if you do not (it no longer does).
862        [Detail: two cases were found: (a) a repeated subpattern containing an
863        extended class; (b) a recursive reference to a subpattern that followed a
864        previous extended class. It wasn't skipping over the extended class
865        correctly when UTF-8 mode was not set.]
867     5. A negated single-character class was not being recognized as fixed-length
868        in lookbehind assertions such as (?<=[^f]), leading to an incorrect
869        compile error "lookbehind assertion is not fixed length".
871     6. The RunPerlTest auxiliary script was showing an unexpected difference
872        between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
873        write a Perl script that can interpret lines of an input file either as
874        byte characters or as UTF-8, which is what "perltest" was being required to
875        do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
876        can't do is switch easily at run time between having the "use utf8;" pragma
877        or not. In the end, I fudged it by using the RunPerlTest script to insert
878        "use utf8;" explicitly for the UTF-8 tests.
880     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
881        the end of the subject string, contrary to the documentation and to what
882        Perl does. This was true of both matching functions. Now it matches only at
883        the start of the subject and immediately after *internal* newlines.
885     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
886        a pointer to an int instead of a pointer to an unsigned long int. This
887        caused problems on 64-bit systems.
889     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
890        instance of the 'standard' template library not being so standard".
892    10. There was no check on the number of named subpatterns nor the maximum
893        length of a subpattern name. The product of these values is used to compute
894        the size of the memory block for a compiled pattern. By supplying a very
895        long subpattern name and a large number of named subpatterns, the size
896        computation could be caused to overflow. This is now prevented by limiting
897        the length of names to 32 characters, and the number of named subpatterns
898        to 10,000.
900    11. Subpatterns that are repeated with specific counts have to be replicated in
901        the compiled pattern. The size of memory for this was computed from the
902        length of the subpattern and the repeat count. The latter is limited to
903        65535, but there was no limit on the former, meaning that integer overflow
904        could in principle occur. The compiled length of a repeated subpattern is
905        now limited to 30,000 bytes in order to prevent this.
907    12. Added the optional facility to have named substrings with the same name.
909    13. Added the ability to use a named substring as a condition, using the
910        Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
911        are numbers (not recommended). Forward references are permitted.
913    14. Added forward references in named backreferences (if you see what I mean).
915    15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
916        pattern could run off the end of the subject. For example, the pattern
917        "(?s)(.{1,5})"8 did this with the subject "ab".
919    16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
920        PCRE_CASELESS was set when matching characters that were quantified with ?
921        or *.
923    17. A character class other than a single negated character that had a minimum
924        but no maximum quantifier - for example [ab]{6,} - was not handled
925        correctly by pce_dfa_exec(). It would match only one character.
927    18. A valid (though odd) pattern that looked like a POSIX character
928        class but used an invalid character after [ (for example [[,abc,]]) caused
929        pcre_compile() to give the error "Failed: internal error: code overflow" or
930        in some cases to crash with a glibc free() error. This could even happen if
931        the pattern terminated after [[ but there just happened to be a sequence of
932        letters, a binary zero, and a closing ] in the memory that followed.
934    19. Perl's treatment of octal escapes in the range \400 to \777 has changed
935        over the years. Originally (before any Unicode support), just the bottom 8
936        bits were taken. Thus, for example, \500 really meant \100. Nowadays the
937        output from "man perlunicode" includes this:
939          The regular expression compiler produces polymorphic opcodes.  That
940          is, the pattern adapts to the data and automatically switches to
941          the Unicode character scheme when presented with Unicode data--or
942          instead uses a traditional byte scheme when presented with byte
943          data.
945        Sadly, a wide octal escape does not cause a switch, and in a string with
946        no other multibyte characters, these octal escapes are treated as before.
947        Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
948        /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
949        Unicode string.
951        I have not perpetrated such confusion in PCRE. Up till now, it took just
952        the bottom 8 bits, as in old Perl. I have now made octal escapes with
953        values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
954        translate to the appropriate multibyte character.
956    29. Applied some refactoring to reduce the number of warnings from Microsoft
957        and Borland compilers. This has included removing the fudge introduced
958        seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
959        a warning about an unused variable.
961    21. PCRE has not included VT (character 0x0b) in the set of whitespace
962        characters since release 4.0, because Perl (from release 5.004) does not.
963        [Or at least, is documented not to: some releases seem to be in conflict
964        with the documentation.] However, when a pattern was studied with
965        pcre_study() and all its branches started with \s, PCRE still included VT
966        as a possible starting character. Of course, this did no harm; it just
967        caused an unnecessary match attempt.
969    22. Removed a now-redundant internal flag bit that recorded the fact that case
970        dependency changed within the pattern. This was once needed for "required
971        byte" processing, but is no longer used. This recovers a now-scarce options
972        bit. Also moved the least significant internal flag bit to the most-
973        significant bit of the word, which was not previously used (hangover from
974        the days when it was an int rather than a uint) to free up another bit for
975        the future.
977    23. Added support for CRLF line endings as well as CR and LF. As well as the
978        default being selectable at build time, it can now be changed at runtime
979        via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
980        specify that it is scanning data with non-default line endings.
982    24. Changed the definition of CXXLINK to make it agree with the definition of
983        LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
985    25. Applied Ian Taylor's patches to avoid using another stack frame for tail
986        recursions. This makes a big different to stack usage for some patterns.
988    26. If a subpattern containing a named recursion or subroutine reference such
989        as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
990        the space required for the compiled pattern went wrong and gave too small a
991        value. Depending on the environment, this could lead to "Failed: internal
992        error: code overflow at offset 49" or "glibc detected double free or
993        corruption" errors.
995    27. Applied patches from Google (a) to support the new newline modes and (b) to
996        advance over multibyte UTF-8 characters in GlobalReplace.
998    28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
999        difference for some implementation of PCRE in some Windows version.
1001    29. Added some extra testing facilities to pcretest:
1003        \q<number>   in a data line sets the "match limit" value
1004        \Q<number>   in a data line sets the "match recursion limt" value
1005        -S <number>  sets the stack size, where <number> is in megabytes
1007        The -S option isn't available for Windows.
1010    Version 6.6 06-Feb-06
1011    ---------------------
1013     1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
1014        in pcreposix.h. I have copied the definition from pcre.h.
1016     2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
1017        because pcre.h is no longer a built file.
1019     3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
1020        not normally included in the compiled code.
1023    Version 6.5 01-Feb-06
1024    ---------------------
1026     1. When using the partial match feature with pcre_dfa_exec(), it was not
1027        anchoring the second and subsequent partial matches at the new starting
1028        point. This could lead to incorrect results. For example, with the pattern
1029        /1234/, partially matching against "123" and then "a4" gave a match.
1031     2. Changes to pcregrep:
1033        (a) All non-match returns from pcre_exec() were being treated as failures
1034            to match the line. Now, unless the error is PCRE_ERROR_NOMATCH, an
1035            error message is output. Some extra information is given for the
1036            PCRE_ERROR_MATCHLIMIT and PCRE_ERROR_RECURSIONLIMIT errors, which are
1037            probably the only errors that are likely to be caused by users (by
1038            specifying a regex that has nested indefinite repeats, for instance).
1039            If there are more than 20 of these errors, pcregrep is abandoned.
1041        (b) A binary zero was treated as data while matching, but terminated the
1042            output line if it was written out. This has been fixed: binary zeroes
1043            are now no different to any other data bytes.
1045        (c) Whichever of the LC_ALL or LC_CTYPE environment variables is set is
1046            used to set a locale for matching. The --locale=xxxx long option has
1047            been added (no short equivalent) to specify a locale explicitly on the
1048            pcregrep command, overriding the environment variables.
1050        (d) When -B was used with -n, some line numbers in the output were one less
1051            than they should have been.
1053        (e) Added the -o (--only-matching) option.
1055        (f) If -A or -C was used with -c (count only), some lines of context were
1056            accidentally printed for the final match.
1058        (g) Added the -H (--with-filename) option.
1060        (h) The combination of options -rh failed to suppress file names for files
1061            that were found from directory arguments.
1063        (i) Added the -D (--devices) and -d (--directories) options.
1065        (j) Added the -F (--fixed-strings) option.
1067        (k) Allow "-" to be used as a file name for -f as well as for a data file.
1069        (l) Added the --colo(u)r option.
1071        (m) Added Jeffrey Friedl's -S testing option, but within #ifdefs so that it
1072            is not present by default.
1074     3. A nasty bug was discovered in the handling of recursive patterns, that is,
1075        items such as (?R) or (?1), when the recursion could match a number of
1076        alternatives. If it matched one of the alternatives, but subsequently,
1077        outside the recursion, there was a failure, the code tried to back up into
1078        the recursion. However, because of the way PCRE is implemented, this is not
1079        possible, and the result was an incorrect result from the match.
1081        In order to prevent this happening, the specification of recursion has
1082        been changed so that all such subpatterns are automatically treated as
1083        atomic groups. Thus, for example, (?R) is treated as if it were (?>(?R)).
1085     4. I had overlooked the fact that, in some locales, there are characters for
1086        which isalpha() is true but neither isupper() nor islower() are true. In
1087        the fr_FR locale, for instance, the \xAA and \xBA characters (ordmasculine
1088        and ordfeminine) are like this. This affected the treatment of \w and \W
1089        when they appeared in character classes, but not when they appeared outside
1090        a character class. The bit map for "word" characters is now created
1091        separately from the results of isalnum() instead of just taking it from the
1092        upper, lower, and digit maps. (Plus the underscore character, of course.)
1094     5. The above bug also affected the handling of POSIX character classes such as
1095        [[:alpha:]] and [[:alnum:]]. These do not have their own bit maps in PCRE's
1096        permanent tables. Instead, the bit maps for such a class were previously
1097        created as the appropriate unions of the upper, lower, and digit bitmaps.
1098        Now they are created by subtraction from the [[:word:]] class, which has
1099        its own bitmap.
1101     6. The [[:blank:]] character class matches horizontal, but not vertical space.
1102        It is created by subtracting the vertical space characters (\x09, \x0a,
1103        \x0b, \x0c) from the [[:space:]] bitmap. Previously, however, the
1104        subtraction was done in the overall bitmap for a character class, meaning
1105        that a class such as [\x0c[:blank:]] was incorrect because \x0c would not
1106        be recognized. This bug has been fixed.
1108     7. Patches from the folks at Google:
1110          (a) pcrecpp.cc: "to handle a corner case that may or may not happen in
1111          real life, but is still worth protecting against".
1113          (b) pcrecpp.cc: "corrects a bug when negative radixes are used with
1114          regular expressions".
1116          (c) pcre_scanner.cc: avoid use of std::count() because not all systems
1117          have it.
1119          (d) Split off pcrecpparg.h from pcrecpp.h and had the former built by
1120          "configure" and the latter not, in order to fix a problem somebody had
1121          with compiling the Arg class on HP-UX.
1123          (e) Improve the error-handling of the C++ wrapper a little bit.
1125          (f) New tests for checking recursion limiting.
1127     8. The pcre_memmove() function, which is used only if the environment does not
1128        have a standard memmove() function (and is therefore rarely compiled),
1129        contained two bugs: (a) use of int instead of size_t, and (b) it was not
1130        returning a result (though PCRE never actually uses the result).
1132     9. In the POSIX regexec() interface, if nmatch is specified as a ridiculously
1133        large number - greater than INT_MAX/(3*sizeof(int)) - REG_ESPACE is
1134        returned instead of calling malloc() with an overflowing number that would
1135        most likely cause subsequent chaos.
1137    10. The debugging option of pcretest was not showing the NO_AUTO_CAPTURE flag.
1139    11. The POSIX flag REG_NOSUB is now supported. When a pattern that was compiled
1140        with this option is matched, the nmatch and pmatch options of regexec() are
1141        ignored.
1143    12. Added REG_UTF8 to the POSIX interface. This is not defined by POSIX, but is
1144        provided in case anyone wants to the the POSIX interface with UTF-8
1145        strings.
1147    13. Added CXXLDFLAGS to the Makefile parameters to provide settings only on the
1148        C++ linking (needed for some HP-UX environments).
1150    14. Avoid compiler warnings in get_ucpname() when compiled without UCP support
1151        (unused parameter) and in the pcre_printint() function (omitted "default"
1152        switch label when the default is to do nothing).
1154    15. Added some code to make it possible, when PCRE is compiled as a C++
1155        library, to replace subject pointers for pcre_exec() with a smart pointer
1156        class, thus making it possible to process discontinuous strings.
1158    16. The two macros PCRE_EXPORT and PCRE_DATA_SCOPE are confusing, and perform
1159        much the same function. They were added by different people who were trying
1160        to make PCRE easy to compile on non-Unix systems. It has been suggested
1161        that PCRE_EXPORT be abolished now that there is more automatic apparatus
1162        for compiling on Windows systems. I have therefore replaced it with
1163        PCRE_DATA_SCOPE. This is set automatically for Windows; if not set it
1164        defaults to "extern" for C or "extern C" for C++, which works fine on
1165        Unix-like systems. It is now possible to override the value of PCRE_DATA_
1166        SCOPE with something explicit in config.h. In addition:
1168        (a) pcreposix.h still had just "extern" instead of either of these macros;
1169            I have replaced it with PCRE_DATA_SCOPE.
1171        (b) Functions such as _pcre_xclass(), which are internal to the library,
1172            but external in the C sense, all had PCRE_EXPORT in their definitions.
1173            This is apparently wrong for the Windows case, so I have removed it.
1174            (It makes no difference on Unix-like systems.)
1176    17. Added a new limit, MATCH_LIMIT_RECURSION, which limits the depth of nesting
1177        of recursive calls to match(). This is different to MATCH_LIMIT because
1178        that limits the total number of calls to match(), not all of which increase
1179        the depth of recursion. Limiting the recursion depth limits the amount of
1180        stack (or heap if NO_RECURSE is set) that is used. The default can be set
1181        when PCRE is compiled, and changed at run time. A patch from Google adds
1182        this functionality to the C++ interface.
1184    18. Changes to the handling of Unicode character properties:
1186        (a) Updated the table to Unicode 4.1.0.
1188        (b) Recognize characters that are not in the table as "Cn" (undefined).
1190        (c) I revised the way the table is implemented to a much improved format
1191            which includes recognition of ranges. It now supports the ranges that
1192            are defined in UnicodeData.txt, and it also amalgamates other
1193            characters into ranges. This has reduced the number of entries in the
1194            table from around 16,000 to around 3,000, thus reducing its size
1195            considerably. I realized I did not need to use a tree structure after
1196            all - a binary chop search is just as efficient. Having reduced the
1197            number of entries, I extended their size from 6 bytes to 8 bytes to
1198            allow for more data.
1200        (d) Added support for Unicode script names via properties such as \p{Han}.
1202    19. In UTF-8 mode, a backslash followed by a non-Ascii character was not
1203        matching that character.
1205    20. When matching a repeated Unicode property with a minimum greater than zero,
1206        (for example \pL{2,}), PCRE could look past the end of the subject if it
1207        reached it while seeking the minimum number of characters. This could
1208        happen only if some of the characters were more than one byte long, because
1209        there is a check for at least the minimum number of bytes.
1211    21. Refactored the implementation of \p and \P so as to be more general, to
1212        allow for more different types of property in future. This has changed the
1213        compiled form incompatibly. Anybody with saved compiled patterns that use
1214        \p or \P will have to recompile them.
1216    22. Added "Any" and "L&" to the supported property types.
1218    23. Recognize \x{...} as a code point specifier, even when not in UTF-8 mode,
1219        but give a compile time error if the value is greater than 0xff.
1221    24. The man pages for pcrepartial, pcreprecompile, and pcre_compile2 were
1222        accidentally not being installed or uninstalled.
1224    25. The pcre.h file was built from pcre.h.in, but the only changes that were
1225        made were to insert the current release number. This seemed silly, because
1226        it made things harder for people building PCRE on systems that don't run
1227        "configure". I have turned pcre.h into a distributed file, no longer built
1228        by "configure", with the version identification directly included. There is
1229        no longer a pcre.h.in file.
1231        However, this change necessitated a change to the pcre-config script as
1232        well. It is built from pcre-config.in, and one of the substitutions was the
1233        release number. I have updated configure.ac so that ./configure now finds
1234        the release number by grepping pcre.h.
1236    26. Added the ability to run the tests under valgrind.
1239    Version 6.4 05-Sep-05
1240    ---------------------
1242     1. Change 6.0/10/(l) to pcregrep introduced a bug that caused separator lines
1243        "--" to be printed when multiple files were scanned, even when none of the
1244        -A, -B, or -C options were used. This is not compatible with Gnu grep, so I
1245        consider it to be a bug, and have restored the previous behaviour.
1247     2. A couple of code tidies to get rid of compiler warnings.
1249     3. The pcretest program used to cheat by referring to symbols in the library
1250        whose names begin with _pcre_. These are internal symbols that are not
1251        really supposed to be visible externally, and in some environments it is
1252        possible to suppress them. The cheating is now confined to including
1253        certain files from the library's source, which is a bit cleaner.
1255     4. Renamed pcre.in as pcre.h.in to go with pcrecpp.h.in; it also makes the
1256        file's purpose clearer.
1258     5. Reorganized pcre_ucp_findchar().
1261    Version 6.3 15-Aug-05
1262    ---------------------
1264     1. The file libpcre.pc.in did not have general read permission in the tarball.
1266     2. There were some problems when building without C++ support:
1268        (a) If C++ support was not built, "make install" and "make test" still
1269            tried to test it.
1271        (b) There were problems when the value of CXX was explicitly set. Some
1272            changes have been made to try to fix these, and ...
1274        (c) --disable-cpp can now be used to explicitly disable C++ support.
1276        (d) The use of @CPP_OBJ@ directly caused a blank line preceded by a
1277            backslash in a target when C++ was disabled. This confuses some
1278            versions of "make", apparently. Using an intermediate variable solves
1279            this. (Same for CPP_LOBJ.)
1281     3. $(LINK_FOR_BUILD) now includes $(CFLAGS_FOR_BUILD) and $(LINK)
1282        (non-Windows) now includes $(CFLAGS) because these flags are sometimes
1283        necessary on certain architectures.
1285     4. Added a setting of -export-symbols-regex to the link command to remove
1286        those symbols that are exported in the C sense, but actually are local
1287        within the library, and not documented. Their names all begin with
1288        "_pcre_". This is not a perfect job, because (a) we have to except some
1289        symbols that pcretest ("illegally") uses, and (b) the facility isn't always
1290        available (and never for static libraries). I have made a note to try to
1291        find a way round (a) in the future.
1294    Version 6.2 01-Aug-05
1295    ---------------------
1297     1. There was no test for integer overflow of quantifier values. A construction
1298        such as {1111111111111111} would give undefined results. What is worse, if
1299        a minimum quantifier for a parenthesized subpattern overflowed and became
1300        negative, the calculation of the memory size went wrong. This could have
1301        led to memory overwriting.
1303     2. Building PCRE using VPATH was broken. Hopefully it is now fixed.
1305     3. Added "b" to the 2nd argument of fopen() in dftables.c, for non-Unix-like
1306        operating environments where this matters.
1308     4. Applied Giuseppe Maxia's patch to add additional features for controlling
1309        PCRE options from within the C++ wrapper.
1311     5. Named capturing subpatterns were not being correctly counted when a pattern
1312        was compiled. This caused two problems: (a) If there were more than 100
1313        such subpatterns, the calculation of the memory needed for the whole
1314        compiled pattern went wrong, leading to an overflow error. (b) Numerical
1315        back references of the form \12, where the number was greater than 9, were
1316        not recognized as back references, even though there were sufficient
1317        previous subpatterns.
1319     6. Two minor patches to pcrecpp.cc in order to allow it to compile on older
1320        versions of gcc, e.g. 2.95.4.
1323    Version 6.1 21-Jun-05
1324    ---------------------
1326     1. There was one reference to the variable "posix" in pcretest.c that was not
1327        surrounded by "#if !defined NOPOSIX".
1329     2. Make it possible to compile pcretest without DFA support, UTF8 support, or
1330        the cross-check on the old pcre_info() function, for the benefit of the
1331        cut-down version of PCRE that is currently imported into Exim.
1333     3. A (silly) pattern starting with (?i)(?-i) caused an internal space
1334        allocation error. I've done the easy fix, which wastes 2 bytes for sensible
1335        patterns that start (?i) but I don't think that matters. The use of (?i) is
1336        just an example; this all applies to the other options as well.
1338     4. Since libtool seems to echo the compile commands it is issuing, the output
1339        from "make" can be reduced a bit by putting "@" in front of each libtool
1340        compile command.
1342     5. Patch from the folks at Google for configure.in to be a bit more thorough
1343        in checking for a suitable C++ installation before trying to compile the
1344        C++ stuff. This should fix a reported problem when a compiler was present,
1345        but no suitable headers.
1347     6. The man pages all had just "PCRE" as their title. I have changed them to
1348        be the relevant file name. I have also arranged that these names are
1349        retained in the file doc/pcre.txt, which is a concatenation in text format
1350        of all the man pages except the little individual ones for each function.
1352     7. The NON-UNIX-USE file had not been updated for the different set of source
1353        files that come with release 6. I also added a few comments about the C++
1354        wrapper.
1357    Version 6.0 07-Jun-05
1358    ---------------------
1360     1. Some minor internal re-organization to help with my DFA experiments.
1362     2. Some missing #ifdef SUPPORT_UCP conditionals in pcretest and printint that
1363        didn't matter for the library itself when fully configured, but did matter
1364        when compiling without UCP support, or within Exim, where the ucp files are
1365        not imported.
1367     3. Refactoring of the library code to split up the various functions into
1368        different source modules. The addition of the new DFA matching code (see
1369        below) to a single monolithic source would have made it really too
1370        unwieldy, quite apart from causing all the code to be include in a
1371        statically linked application, when only some functions are used. This is
1372        relevant even without the DFA addition now that patterns can be compiled in
1373        one application and matched in another.
1375        The downside of splitting up is that there have to be some external
1376        functions and data tables that are used internally in different modules of
1377        the library but which are not part of the API. These have all had their
1378        names changed to start with "_pcre_" so that they are unlikely to clash
1379        with other external names.
1381     4. Added an alternate matching function, pcre_dfa_exec(), which matches using
1382        a different (DFA) algorithm. Although it is slower than the original
1383        function, it does have some advantages for certain types of matching
1384        problem.
1386     5. Upgrades to pcretest in order to test the features of pcre_dfa_exec(),
1387        including restarting after a partial match.
1389     6. A patch for pcregrep that defines INVALID_FILE_ATTRIBUTES if it is not
1390        defined when compiling for Windows was sent to me. I have put it into the
1391        code, though I have no means of testing or verifying it.
1393     7. Added the pcre_refcount() auxiliary function.
1395     8. Added the PCRE_FIRSTLINE option. This constrains an unanchored pattern to
1396        match before or at the first newline in the subject string. In pcretest,
1397        the /f option on a pattern can be used to set this.
1399     9. A repeated \w when used in UTF-8 mode with characters greater than 256
1400        would behave wrongly. This has been present in PCRE since release 4.0.
1402    10. A number of changes to the pcregrep command:
1404        (a) Refactored how -x works; insert ^(...)$ instead of setting
1405            PCRE_ANCHORED and checking the length, in preparation for adding
1406            something similar for -w.
1408        (b) Added the -w (match as a word) option.
1410        (c) Refactored the way lines are read and buffered so as to have more
1411            than one at a time available.
1413        (d) Implemented a pcregrep test script.
1415        (e) Added the -M (multiline match) option. This allows patterns to match
1416            over several lines of the subject. The buffering ensures that at least
1417            8K, or the rest of the document (whichever is the shorter) is available
1418            for matching (and similarly the previous 8K for lookbehind assertions).
1420        (f) Changed the --help output so that it now says
1422              -w, --word-regex(p)
1424            instead of two lines, one with "regex" and the other with "regexp"
1425            because that confused at least one person since the short forms are the
1426            same. (This required a bit of code, as the output is generated
1427            automatically from a table. It wasn't just a text change.)
1429        (g) -- can be used to terminate pcregrep options if the next thing isn't an
1430            option but starts with a hyphen. Could be a pattern or a path name
1431            starting with a hyphen, for instance.
1433        (h) "-" can be given as a file name to represent stdin.
1435        (i) When file names are being printed, "(standard input)" is used for
1436            the standard input, for compatibility with GNU grep. Previously
1437            "<stdin>" was used.
1439        (j) The option --label=xxx can be used to supply a name to be used for
1440            stdin when file names are being printed. There is no short form.
1442        (k) Re-factored the options decoding logic because we are going to add
1443            two more options that take data. Such options can now be given in four
1444            different ways, e.g. "-fname", "-f name", "--file=name", "--file name".
1446        (l) Added the -A, -B, and -C options for requesting that lines of context
1447            around matches be printed.
1449        (m) Added the -L option to print the names of files that do not contain
1450            any matching lines, that is, the complement of -l.
1452        (n) The return code is 2 if any file cannot be opened, but pcregrep does
1453            continue to scan other files.
1455        (o) The -s option was incorrectly implemented. For compatibility with other
1456            greps, it now suppresses the error message for a non-existent or non-
1457            accessible file (but not the return code). There is a new option called
1458            -q that suppresses the output of matching lines, which was what -s was
1459            previously doing.
1461        (p) Added --include and --exclude options to specify files for inclusion
1462            and exclusion when recursing.
1464    11. The Makefile was not using the Autoconf-supported LDFLAGS macro properly.
1465        Hopefully, it now does.
1467    12. Missing cast in pcre_study().
1469    13. Added an "uninstall" target to the makefile.
1471    14. Replaced "extern" in the function prototypes in Makefile.in with
1472        "PCRE_DATA_SCOPE", which defaults to 'extern' or 'extern "C"' in the Unix
1473        world, but is set differently for Windows.
1475    15. Added a second compiling function called pcre_compile2(). The only
1476        difference is that it has an extra argument, which is a pointer to an
1477        integer error code. When there is a compile-time failure, this is set
1478        non-zero, in addition to the error test pointer being set to point to an
1479        error message. The new argument may be NULL if no error number is required
1480        (but then you may as well call pcre_compile(), which is now just a
1481        wrapper). This facility is provided because some applications need a
1482        numeric error indication, but it has also enabled me to tidy up the way
1483        compile-time errors are handled in the POSIX wrapper.
1485    16. Added VPATH=.libs to the makefile; this should help when building with one
1486        prefix path and installing with another. (Or so I'm told by someone who
1487        knows more about this stuff than I do.)
1489    17. Added a new option, REG_DOTALL, to the POSIX function regcomp(). This
1490        passes PCRE_DOTALL to the pcre_compile() function, making the "." character
1491        match everything, including newlines. This is not POSIX-compatible, but
1492        somebody wanted the feature. From pcretest it can be activated by using
1493        both the P and the s flags.
1495    18. AC_PROG_LIBTOOL appeared twice in Makefile.in. Removed one.
1497    19. libpcre.pc was being incorrectly installed as executable.
1499    20. A couple of places in pcretest check for end-of-line by looking for '\n';
1500        it now also looks for '\r' so that it will work unmodified on Windows.
1502    21. Added Google's contributed C++ wrapper to the distribution.
1504    22. Added some untidy missing memory free() calls in pcretest, to keep
1505        Electric Fence happy when testing.
1509    Version 5.0 13-Sep-04
1510    ---------------------
1512     1. Internal change: literal characters are no longer packed up into items
1513        containing multiple characters in a single byte-string. Each character
1514        is now matched using a separate opcode. However, there may be more than one
1515        byte in the character in UTF-8 mode.
1517     2. The pcre_callout_block structure has two new fields: pattern_position and
1518        next_item_length. These contain the offset in the pattern to the next match
1519        item, and its length, respectively.
1521     3. The PCRE_AUTO_CALLOUT option for pcre_compile() requests the automatic
1522        insertion of callouts before each pattern item. Added the /C option to
1523        pcretest to make use of this.
1525     4. On the advice of a Windows user, the lines
1527          #if defined(_WIN32) || defined(WIN32)
1528          _setmode( _fileno( stdout ), 0x8000 );
1529          #endif  /* defined(_WIN32) || defined(WIN32) */
1531        have been added to the source of pcretest. This apparently does useful
1532        magic in relation to line terminators.
1534     5. Changed "r" and "w" in the calls to fopen() in pcretest to "rb" and "wb"
1535        for the benefit of those environments where the "b" makes a difference.
1537     6. The icc compiler has the same options as gcc, but "configure" doesn't seem
1538        to know about it. I have put a hack into configure.in that adds in code
1539        to set GCC=yes if CC=icc. This seems to end up at a point in the
1540        generated configure script that is early enough to affect the setting of
1541        compiler options, which is what is needed, but I have no means of testing
1542        whether it really works. (The user who reported this had patched the
1543        generated configure script, which of course I cannot do.)
1545        LATER: After change 22 below (new libtool files), the configure script
1546        seems to know about icc (and also ecc). Therefore, I have commented out
1547        this hack in configure.in.
1549     7. Added support for pkg-config (2 patches were sent in).
1551     8. Negated POSIX character classes that used a combination of internal tables
1552        were completely broken. These were [[:^alpha:]], [[:^alnum:]], and
1553        [[:^ascii]]. Typically, they would match almost any characters. The other
1554        POSIX classes were not broken in this way.
1556     9. Matching the pattern "\b.*?" against "ab cd", starting at offset 1, failed
1557        to find the match, as PCRE was deluded into thinking that the match had to
1558        start at the start point or following a newline. The same bug applied to
1559        patterns with negative forward assertions or any backward assertions
1560        preceding ".*" at the start, unless the pattern required a fixed first
1561        character. This was a failing pattern: "(?!.bcd).*". The bug is now fixed.
1563    10. In UTF-8 mode, when moving forwards in the subject after a failed match
1564        starting at the last subject character, bytes beyond the end of the subject
1565        string were read.
1567    11. Renamed the variable "class" as "classbits" to make life easier for C++
1568        users. (Previously there was a macro definition, but it apparently wasn't
1569        enough.)
1571    12. Added the new field "tables" to the extra data so that tables can be passed
1572        in at exec time, or the internal tables can be re-selected. This allows
1573        a compiled regex to be saved and re-used at a later time by a different
1574        program that might have everything at different addresses.
1576    13. Modified the pcre-config script so that, when run on Solaris, it shows a
1577        -R library as well as a -L library.
1579    14. The debugging options of pcretest (-d on the command line or D on a
1580        pattern) showed incorrect output for anything following an extended class
1581        that contained multibyte characters and which was followed by a quantifier.
1583    15. Added optional support for general category Unicode character properties
1584        via the \p, \P, and \X escapes. Unicode property support implies UTF-8
1585        support. It adds about 90K to the size of the library. The meanings of the
1586        inbuilt class escapes such as \d and \s have NOT been changed.
1588    16. Updated pcredemo.c to include calls to free() to release the memory for the
1589        compiled pattern.
1591    17. The generated file chartables.c was being created in the source directory
1592        instead of in the building directory. This caused the build to fail if the
1593        source directory was different from the building directory, and was
1594        read-only.
1596    18. Added some sample Win commands from Mark Tetrode into the NON-UNIX-USE
1597        file. No doubt somebody will tell me if they don't make sense... Also added
1598        Dan Mooney's comments about building on OpenVMS.
1600    19. Added support for partial matching via the PCRE_PARTIAL option for
1601        pcre_exec() and the \P data escape in pcretest.
1603    20. Extended pcretest with 3 new pattern features:
1605        (i)   A pattern option of the form ">rest-of-line" causes pcretest to
1606              write the compiled pattern to the file whose name is "rest-of-line".
1607              This is a straight binary dump of the data, with the saved pointer to
1608              the character tables forced to be NULL. The study data, if any, is
1609              written too. After writing, pcretest reads a new pattern.
1611        (ii)  If, instead of a pattern, "<rest-of-line" is given, pcretest reads a
1612              compiled pattern from the given file. There must not be any
1613              occurrences of "<" in the file name (pretty unlikely); if there are,
1614              pcretest will instead treat the initial "<" as a pattern delimiter.
1615              After reading in the pattern, pcretest goes on to read data lines as
1616              usual.
1618        (iii) The F pattern option causes pcretest to flip the bytes in the 32-bit
1619              and 16-bit fields in a compiled pattern, to simulate a pattern that
1620              was compiled on a host of opposite endianness.
1622    21. The pcre-exec() function can now cope with patterns that were compiled on
1623        hosts of opposite endianness, with this restriction:
1625          As for any compiled expression that is saved and used later, the tables
1626          pointer field cannot be preserved; the extra_data field in the arguments
1627          to pcre_exec() should be used to pass in a tables address if a value
1628          other than the default internal tables were used at compile time.
1630    22. Calling pcre_exec() with a negative value of the "ovecsize" parameter is
1631        now diagnosed as an error. Previously, most of the time, a negative number
1632        would have been treated as zero, but if in addition "ovector" was passed as
1633        NULL, a crash could occur.
1635    23. Updated the files ltmain.sh, config.sub, config.guess, and aclocal.m4 with
1636        new versions from the libtool 1.5 distribution (the last one is a copy of
1637        a file called libtool.m4). This seems to have fixed the need to patch
1638        "configure" to support Darwin 1.3 (which I used to do). However, I still
1639        had to patch ltmain.sh to ensure that ${SED} is set (it isn't on my
1640        workstation).
1642    24. Changed the PCRE licence to be the more standard "BSD" licence.
1645    Version 4.5 01-Dec-03
1646    ---------------------
1648     1. There has been some re-arrangement of the code for the match() function so
1649        that it can be compiled in a version that does not call itself recursively.
1650        Instead, it keeps those local variables that need separate instances for
1651        each "recursion" in a frame on the heap, and gets/frees frames whenever it
1652        needs to "recurse". Keeping track of where control must go is done by means
1653        of setjmp/longjmp. The whole thing is implemented by a set of macros that
1654        hide most of the details from the main code, and operates only if
1655        NO_RECURSE is defined while compiling pcre.c. If PCRE is built using the
1656        "configure" mechanism, "--disable-stack-for-recursion" turns on this way of
1657        operating.
1659        To make it easier for callers to provide specially tailored get/free
1660        functions for this usage, two new functions, pcre_stack_malloc, and
1661        pcre_stack_free, are used. They are always called in strict stacking order,
1662        and the size of block requested is always the same.
1664        The PCRE_CONFIG_STACKRECURSE info parameter can be used to find out whether
1665        PCRE has been compiled to use the stack or the heap for recursion. The
1666        -C option of pcretest uses this to show which version is compiled.
1668        A new data escape \S, is added to pcretest; it causes the amounts of store
1669        obtained and freed by both kinds of malloc/free at match time to be added
1670        to the output.
1672     2. Changed the locale test to use "fr_FR" instead of "fr" because that's
1673        what's available on my current Linux desktop machine.
1675     3. When matching a UTF-8 string, the test for a valid string at the start has
1676        been extended. If start_offset is not zero, PCRE now checks that it points
1677        to a byte that is the start of a UTF-8 character. If not, it returns
1678        PCRE_ERROR_BADUTF8_OFFSET (-11). Note: the whole string is still checked;
1679        this is necessary because there may be backward assertions in the pattern.
1680        When matching the same subject several times, it may save resources to use
1681        PCRE_NO_UTF8_CHECK on all but the first call if the string is long.
1683     4. The code for checking the validity of UTF-8 strings has been tightened so
1684        that it rejects (a) strings containing 0xfe or 0xff bytes and (b) strings
1685        containing "overlong sequences".
1687     5. Fixed a bug (appearing twice) that I could not find any way of exploiting!
1688        I had written "if ((digitab[*p++] && chtab_digit) == 0)" where the "&&"
1689        should have been "&", but it just so happened that all the cases this let
1690        through by mistake were picked up later in the function.
1692     6. I had used a variable called "isblank" - this is a C99 function, causing
1693        some compilers to warn. To avoid this, I renamed it (as "blankclass").
1695     7. Cosmetic: (a) only output another newline at the end of pcretest if it is
1696        prompting; (b) run "./pcretest /dev/null" at the start of the test script
1697        so the version is shown; (c) stop "make test" echoing "./RunTest".
1699     8. Added patches from David Burgess to enable PCRE to run on EBCDIC systems.
1701     9. The prototype for memmove() for systems that don't have it was using
1702        size_t, but the inclusion of the header that defines size_t was later. I've
1703        moved the #includes for the C headers earlier to avoid this.
1705    10. Added some adjustments to the code to make it easier to compiler on certain
1706        special systems:
1708          (a) Some "const" qualifiers were missing.
1709          (b) Added the macro EXPORT before all exported functions; by default this
1710              is defined to be empty.
1711          (c) Changed the dftables auxiliary program (that builds chartables.c) so
1712              that it reads its output file name as an argument instead of writing
1713              to the standard output and assuming this can be redirected.
1715    11. In UTF-8 mode, if a recursive reference (e.g. (?1)) followed a character
1716        class containing characters with values greater than 255, PCRE compilation
1717        went into a loop.
1719    12. A recursive reference to a subpattern that was within another subpattern
1720        that had a minimum quantifier of zero caused PCRE to crash. For example,
1721        (x(y(?2))z)? provoked this bug with a subject that got as far as the
1722        recursion. If the recursively-called subpattern itself had a zero repeat,
1723        that was OK.
1725    13. In pcretest, the buffer for reading a data line was set at 30K, but the
1726        buffer into which it was copied (for escape processing) was still set at
1727        1024, so long lines caused crashes.
1729    14. A pattern such as /[ab]{1,3}+/ failed to compile, giving the error
1730        "internal error: code overflow...". This applied to any character class
1731        that was followed by a possessive quantifier.
1733    15. Modified the Makefile to add libpcre.la as a prerequisite for
1734        libpcreposix.la because I was told this is needed for a parallel build to
1735        work.
1737    16. If a pattern that contained .* following optional items at the start was
1738        studied, the wrong optimizing data was generated, leading to matching
1739        errors. For example, studying /[ab]*.*c/ concluded, erroneously, that any
1740        matching string must start with a or b or c. The correct conclusion for
1741        this pattern is that a match can start with any character.
1744    Version 4.4 13-Aug-03
1745    ---------------------
1747     1. In UTF-8 mode, a character class containing characters with values between
1748        127 and 255 was not handled correctly if the compiled pattern was studied.
1749        In fixing this, I have also improved the studying algorithm for such
1750        classes (slightly).
1752     2. Three internal functions had redundant arguments passed to them. Removal
1753        might give a very teeny performance improvement.
1755     3. Documentation bug: the value of the capture_top field in a callout is *one
1756        more than* the number of the hightest numbered captured substring.
1758     4. The Makefile linked pcretest and pcregrep with -lpcre, which could result
1759        in incorrectly linking with a previously installed version. They now link
1760        explicitly with libpcre.la.
1762     5. configure.in no longer needs to recognize Cygwin specially.
1764     6. A problem in pcre.in for Windows platforms is fixed.
1766     7. If a pattern was successfully studied, and the -d (or /D) flag was given to
1767        pcretest, it used to include the size of the study block as part of its
1768        output. Unfortunately, the structure contains a field that has a different
1769        size on different hardware architectures. This meant that the tests that
1770        showed this size failed. As the block is currently always of a fixed size,
1771        this information isn't actually particularly useful in pcretest output, so
1772        I have just removed it.
1774     8. Three pre-processor statements accidentally did not start in column 1.
1775        Sadly, there are *still* compilers around that complain, even though
1776        standard C has not required this for well over a decade. Sigh.
1778     9. In pcretest, the code for checking callouts passed small integers in the
1779        callout_data field, which is a void * field. However, some picky compilers
1780        complained about the casts involved for this on 64-bit systems. Now
1781        pcretest passes the address of the small integer instead, which should get
1782        rid of the warnings.
1784    10. By default, when in UTF-8 mode, PCRE now checks for valid UTF-8 strings at
1785        both compile and run time, and gives an error if an invalid UTF-8 sequence
1786        is found. There is a option for disabling this check in cases where the
1787        string is known to be correct and/or the maximum performance is wanted.
1789    11. In response to a bug report, I changed one line in Makefile.in from
1791            -Wl,--out-implib,.libs/lib@WIN_PREFIX@pcreposix.dll.a \
1792        to
1793            -Wl,--out-implib,.libs/@WIN_PREFIX@libpcreposix.dll.a \
1795        to look similar to other lines, but I have no way of telling whether this
1796        is the right thing to do, as I do not use Windows. No doubt I'll get told
1797        if it's wrong...
1800    Version 4.3 21-May-03
1801    ---------------------
1803    1. Two instances of @WIN_PREFIX@ omitted from the Windows targets in the
1804       Makefile.
1806    2. Some refactoring to improve the quality of the code:
1808       (i)   The utf8_table... variables are now declared "const".
1810       (ii)  The code for \cx, which used the "case flipping" table to upper case
1811             lower case letters, now just substracts 32. This is ASCII-specific,
1812             but the whole concept of \cx is ASCII-specific, so it seems
1813             reasonable.
1815       (iii) PCRE was using its character types table to recognize decimal and
1816             hexadecimal digits in the pattern. This is silly, because it handles
1817             only 0-9, a-f, and A-F, but the character types table is locale-
1818             specific, which means strange things might happen. A private
1819             table is now used for this - though it costs 256 bytes, a table is
1820             much faster than multiple explicit tests. Of course, the standard
1821             character types table is still used for matching digits in subject
1822             strings against \d.
1824       (iv)  Strictly, the identifier ESC_t is reserved by POSIX (all identifiers
1825             ending in _t are). So I've renamed it as ESC_tee.
1827    3. The first argument for regexec() in the POSIX wrapper should have been
1828       defined as "const".
1830    4. Changed pcretest to use malloc() for its buffers so that they can be
1831       Electric Fenced for debugging.
1833    5. There were several places in the code where, in UTF-8 mode, PCRE would try
1834       to read one or more bytes before the start of the subject string. Often this
1835       had no effect on PCRE's behaviour, but in some circumstances it could
1836       provoke a segmentation fault.
1838    6. A lookbehind at the start of a pattern in UTF-8 mode could also cause PCRE
1839       to try to read one or more bytes before the start of the subject string.
1841    7. A lookbehind in a pattern matched in non-UTF-8 mode on a PCRE compiled with
1842       UTF-8 support could misbehave in various ways if the subject string
1843       contained bytes with the 0x80 bit set and the 0x40 bit unset in a lookbehind
1844       area. (PCRE was not checking for the UTF-8 mode flag, and trying to move
1845       back over UTF-8 characters.)
1848    Version 4.2 14-Apr-03
1849    ---------------------
1851    1. Typo "#if SUPPORT_UTF8" instead of "#ifdef SUPPORT_UTF8" fixed.
1853    2. Changes to the building process, supplied by Ronald Landheer-Cieslak
1854         [ON_WINDOWS]: new variable, "#" on non-Windows platforms
1855         [NOT_ON_WINDOWS]: new variable, "#" on Windows platforms
1856         [WIN_PREFIX]: new variable, "cyg" for Cygwin
1857         * Makefile.in: use autoconf substitution for OBJEXT, EXEEXT, BUILD_OBJEXT
1858           and BUILD_EXEEXT
1859         Note: automatic setting of the BUILD variables is not yet working
1860         set CPPFLAGS and BUILD_CPPFLAGS (but don't use yet) - should be used at
1861           compile-time but not at link-time
1862         [LINK]: use for linking executables only
1863         make different versions for Windows and non-Windows
1864         [LINKLIB]: new variable, copy of UNIX-style LINK, used for linking
1865           libraries
1866         [LINK_FOR_BUILD]: new variable
1867         [OBJEXT]: use throughout
1868         [EXEEXT]: use throughout
1869         <winshared>: new target
1870         <wininstall>: new target
1871         <dftables.o>: use native compiler
1872         <dftables>: use native linker
1873         <install>: handle Windows platform correctly
1874         <clean>: ditto
1875         <check>: ditto
1876         copy DLL to top builddir before testing
1878       As part of these changes, -no-undefined was removed again. This was reported
1879       to give trouble on HP-UX 11.0, so getting rid of it seems like a good idea
1880       in any case.
1882    3. Some tidies to get rid of compiler warnings:
1884       . In the match_data structure, match_limit was an unsigned long int, whereas
1885         match_call_count was an int. I've made them both unsigned long ints.
1887       . In pcretest the fact that a const uschar * doesn't automatically cast to
1888         a void * provoked a warning.
1890       . Turning on some more compiler warnings threw up some "shadow" variables
1891         and a few more missing casts.
1893    4. If PCRE was complied with UTF-8 support, but called without the PCRE_UTF8
1894       option, a class that contained a single character with a value between 128
1895       and 255 (e.g. /[\xFF]/) caused PCRE to crash.
1897    5. If PCRE was compiled with UTF-8 support, but called without the PCRE_UTF8
1898       option, a class that contained several characters, but with at least one
1899       whose value was between 128 and 255 caused PCRE to crash.
1902    Version 4.1 12-Mar-03
1903    ---------------------
1905    1. Compiling with gcc -pedantic found a couple of places where casts were
1906    needed, and a string in dftables.c that was longer than standard compilers are
1907    required to support.
1909    2. Compiling with Sun's compiler found a few more places where the code could
1910    be tidied up in order to avoid warnings.
1912    3. The variables for cross-compiling were called HOST_CC and HOST_CFLAGS; the
1913    first of these names is deprecated in the latest Autoconf in favour of the name
1914    CC_FOR_BUILD, because "host" is typically used to mean the system on which the
1915    compiled code will be run. I can't find a reference for HOST_CFLAGS, but by
1916    analogy I have changed it to CFLAGS_FOR_BUILD.
1918    4. Added -no-undefined to the linking command in the Makefile, because this is
1919    apparently helpful for Windows. To make it work, also added "-L. -lpcre" to the
1920    linking step for the pcreposix library.
1922    5. PCRE was failing to diagnose the case of two named groups with the same
1923    name.
1925    6. A problem with one of PCRE's optimizations was discovered. PCRE remembers a
1926    literal character that is needed in the subject for a match, and scans along to
1927    ensure that it is present before embarking on the full matching process. This
1928    saves time in cases of nested unlimited repeats that are never going to match.
1929    Problem: the scan can take a lot of time if the subject is very long (e.g.
1930    megabytes), thus penalizing straightforward matches. It is now done only if the
1931    amount of subject to be scanned is less than 1000 bytes.
1933    7. A lesser problem with the same optimization is that it was recording the
1934    first character of an anchored pattern as "needed", thus provoking a search
1935    right along the subject, even when the first match of the pattern was going to
1936    fail. The "needed" character is now not set for anchored patterns, unless it
1937    follows something in the pattern that is of non-fixed length. Thus, it still
1938    fulfils its original purpose of finding quick non-matches in cases of nested
1939    unlimited repeats, but isn't used for simple anchored patterns such as /^abc/.
1942    Version 4.0 17-Feb-03
1943    ---------------------
1945    1. If a comment in an extended regex that started immediately after a meta-item
1946    extended to the end of string, PCRE compiled incorrect data. This could lead to
1947    all kinds of weird effects. Example: /#/ was bad; /()#/ was bad; /a#/ was not.
1949    2. Moved to autoconf 2.53 and libtool 1.4.2.
1951    3. Perl 5.8 no longer needs "use utf8" for doing UTF-8 things. Consequently,
1952    the special perltest8 script is no longer needed - all the tests can be run
1953    from a single perltest script.
1955    4. From 5.004, Perl has not included the VT character (0x0b) in the set defined
1956    by \s. It has now been removed in PCRE. This means it isn't recognized as
1957    whitespace in /x regexes too, which is the same as Perl. Note that the POSIX
1958    class [:space:] *does* include VT, thereby creating a mess.
1960    5. Added the class [:blank:] (a GNU extension from Perl 5.8) to match only
1961    space and tab.
1963    6. Perl 5.005 was a long time ago. It's time to amalgamate the tests that use
1964    its new features into the main test script, reducing the number of scripts.
1966    7. Perl 5.8 has changed the meaning of patterns like /a(?i)b/. Earlier versions
1967    were backward compatible, and made the (?i) apply to the whole pattern, as if
1968    /i were given. Now it behaves more logically, and applies the option setting
1969    only to what follows. PCRE has been changed to follow suit. However, if it
1970    finds options settings right at the start of the pattern, it extracts them into
1971    the global options, as before. Thus, they show up in the info data.
1973    8. Added support for the \Q...\E escape sequence. Characters in between are
1974    treated as literals. This is slightly different from Perl in that $ and @ are
1975    also handled as literals inside the quotes. In Perl, they will cause variable
1976    interpolation. Note the following examples:
1978        Pattern            PCRE matches      Perl matches
1980        \Qabc$xyz\E        abc$xyz           abc followed by the contents of $xyz
1981        \Qabc\$xyz\E       abc\$xyz          abc\$xyz
1982        \Qabc\E\$\Qxyz\E   abc$xyz           abc$xyz
1984    For compatibility with Perl, \Q...\E sequences are recognized inside character
1985    classes as well as outside them.
1987    9. Re-organized 3 code statements in pcretest to avoid "overflow in
1988    floating-point constant arithmetic" warnings from a Microsoft compiler. Added a
1989    (size_t) cast to one statement in pcretest and one in pcreposix to avoid
1990    signed/unsigned warnings.
1992    10. SunOS4 doesn't have strtoul(). This was used only for unpicking the -o
1993    option for pcretest, so I've replaced it by a simple function that does just
1994    that job.
1996    11. pcregrep was ending with code 0 instead of 2 for the commands "pcregrep" or
1997    "pcregrep -".
1999    12. Added "possessive quantifiers" ?+, *+, ++, and {,}+ which come from Sun's
2000    Java package. This provides some syntactic sugar for simple cases of what my
2001    documentation calls "once-only subpatterns". A pattern such as x*+ is the same
2002    as (?>x*). In other words, if what is inside (?>...) is just a single repeated
2003    item, you can use this simplified notation. Note that only makes sense with
2004    greedy quantifiers. Consequently, the use of the possessive quantifier forces
2005    greediness, whatever the setting of the PCRE_UNGREEDY option.
2007    13. A change of greediness default within a pattern was not taking effect at
2008    the current level for patterns like /(b+(?U)a+)/. It did apply to parenthesized
2009    subpatterns that followed. Patterns like /b+(?U)a+/ worked because the option
2010    was abstracted outside.
2012    14. PCRE now supports the \G assertion. It is true when the current matching
2013    position is at the start point of the match. This differs from \A when the
2014    starting offset is non-zero. Used with the /g option of pcretest (or similar
2015    code), it works in the same way as it does for Perl's /g option. If all
2016    alternatives of a regex begin with \G, the expression is anchored to the start
2017    match position, and the "anchored" flag is set in the compiled expression.
2019    15. Some bugs concerning the handling of certain option changes within patterns
2020    have been fixed. These applied to options other than (?ims). For example,
2021    "a(?x: b c )d" did not match "XabcdY" but did match "Xa b c dY". It should have
2022    been the other way round. Some of this was related to change 7 above.
2024    16. PCRE now gives errors for /[.x.]/ and /[=x=]/ as unsupported POSIX
2025    features, as Perl does. Previously, PCRE gave the warnings only for /[[.x.]]/
2026    and /[[=x=]]/. PCRE now also gives an error for /[:name:]/ because it supports
2027    POSIX classes only within a class (e.g. /[[:alpha:]]/).
2029    17. Added support for Perl's \C escape. This matches one byte, even in UTF8
2030    mode. Unlike ".", it always matches newline, whatever the setting of
2031    PCRE_DOTALL. However, PCRE does not permit \C to appear in lookbehind
2032    assertions. Perl allows it, but it doesn't (in general) work because it can't
2033    calculate the length of the lookbehind. At least, that's the case for Perl
2034    5.8.0 - I've been told they are going to document that it doesn't work in
2035    future.
2037    18. Added an error diagnosis for escapes that PCRE does not support: these are
2038    \L, \l, \N, \P, \p, \U, \u, and \X.
2040    19. Although correctly diagnosing a missing ']' in a character class, PCRE was
2041    reading past the end of the pattern in cases such as /[abcd/.
2043    20. PCRE was getting more memory than necessary for patterns with classes that
2044    contained both POSIX named classes and other characters, e.g. /[[:space:]abc/.
2046    21. Added some code, conditional on #ifdef VPCOMPAT, to make life easier for
2047    compiling PCRE for use with Virtual Pascal.
2049    22. Small fix to the Makefile to make it work properly if the build is done
2050    outside the source tree.
2052    23. Added a new extension: a condition to go with recursion. If a conditional
2053    subpattern starts with (?(R) the "true" branch is used if recursion has
2054    happened, whereas the "false" branch is used only at the top level.
2056    24. When there was a very long string of literal characters (over 255 bytes
2057    without UTF support, over 250 bytes with UTF support), the computation of how
2058    much memory was required could be incorrect, leading to segfaults or other
2059    strange effects.
2061    25. PCRE was incorrectly assuming anchoring (either to start of subject or to
2062    start of line for a non-DOTALL pattern) when a pattern started with (.*) and
2063    there was a subsequent back reference to those brackets. This meant that, for
2064    example, /(.*)\d+\1/ failed to match "abc123bc". Unfortunately, it isn't
2065    possible to check for precisely this case. All we can do is abandon the
2066    optimization if .* occurs inside capturing brackets when there are any back
2067    references whatsoever. (See below for a better fix that came later.)
2069    26. The handling of the optimization for finding the first character of a
2070    non-anchored pattern, and for finding a character that is required later in the
2071    match were failing in some cases. This didn't break the matching; it just
2072    failed to optimize when it could. The way this is done has been re-implemented.
2074    27. Fixed typo in error message for invalid (?R item (it said "(?p").
2076    28. Added a new feature that provides some of the functionality that Perl
2077    provides with (?{...}). The facility is termed a "callout". The way it is done
2078    in PCRE is for the caller to provide an optional function, by setting
2079    pcre_callout to its entry point. Like pcre_malloc and pcre_free, this is a
2080    global variable. By default it is unset, which disables all calling out. To get
2081    the function called, the regex must include (?C) at appropriate points. This
2082    is, in fact, equivalent to (?C0), and any number <= 255 may be given with (?C).
2083    This provides a means of identifying different callout points. When PCRE
2084    reaches such a point in the regex, if pcre_callout has been set, the external
2085    function is called. It is provided with data in a structure called
2086    pcre_callout_block, which is defined in pcre.h. If the function returns 0,
2087    matching continues; if it returns a non-zero value, the match at the current
2088    point fails. However, backtracking will occur if possible. [This was changed
2089    later and other features added - see item 49 below.]
2091    29. pcretest is upgraded to test the callout functionality. It provides a
2092    callout function that displays information. By default, it shows the start of
2093    the match and the current position in the text. There are some new data escapes
2094    to vary what happens:
2096        \C+         in addition, show current contents of captured substrings
2097        \C-         do not supply a callout function
2098        \C!n        return 1 when callout number n is reached
2099        \C!n!m      return 1 when callout number n is reached for the mth time
2101    30. If pcregrep was called with the -l option and just a single file name, it
2102    output "<stdin>" if a match was found, instead of the file name.
2104    31. Improve the efficiency of the POSIX API to PCRE. If the number of capturing
2105    slots is less than POSIX_MALLOC_THRESHOLD, use a block on the stack to pass to
2106    pcre_exec(). This saves a malloc/free per call. The default value of
2107    POSIX_MALLOC_THRESHOLD is 10; it can be changed by --with-posix-malloc-threshold
2108    when configuring.
2110    32. The default maximum size of a compiled pattern is 64K. There have been a
2111    few cases of people hitting this limit. The code now uses macros to handle the
2112    storing of links as offsets within the compiled pattern. It defaults to 2-byte
2113    links, but this can be changed to 3 or 4 bytes by --with-link-size when
2114    configuring. Tests 2 and 5 work only with 2-byte links because they output
2115    debugging information about compiled patterns.
2117    33. Internal code re-arrangements:
2119    (a) Moved the debugging function for printing out a compiled regex into
2120        its own source file (printint.c) and used #include to pull it into
2121        pcretest.c and, when DEBUG is defined, into pcre.c, instead of having two
2122        separate copies.
2124    (b) Defined the list of op-code names for debugging as a macro in
2125        internal.h so that it is next to the definition of the opcodes.
2127    (c) Defined a table of op-code lengths for simpler skipping along compiled
2128        code. This is again a macro in internal.h so that it is next to the
2129        definition of the opcodes.
2131    34. Added support for recursive calls to individual subpatterns, along the
2132    lines of Robin Houston's patch (but implemented somewhat differently).
2134    35. Further mods to the Makefile to help Win32. Also, added code to pcregrep to
2135    allow it to read and process whole directories in Win32. This code was
2136    contributed by Lionel Fourquaux; it has not been tested by me.
2138    36. Added support for named subpatterns. The Python syntax (?P<name>...) is
2139    used to name a group. Names consist of alphanumerics and underscores, and must
2140    be unique. Back references use the syntax (?P=name) and recursive calls use
2141    (?P>name) which is a PCRE extension to the Python extension. Groups still have
2142    numbers. The function pcre_fullinfo() can be used after compilation to extract
2143    a name/number map. There are three relevant calls:
2145      PCRE_INFO_NAMEENTRYSIZE        yields the size of each entry in the map
2146      PCRE_INFO_NAMECOUNT            yields the number of entries
2147      PCRE_INFO_NAMETABLE            yields a pointer to the map.
2149    The map is a vector of fixed-size entries. The size of each entry depends on
2150    the length of the longest name used. The first two bytes of each entry are the
2151    group number, most significant byte first. There follows the corresponding
2152    name, zero terminated. The names are in alphabetical order.
2154    37. Make the maximum literal string in the compiled code 250 for the non-UTF-8
2155    case instead of 255. Making it the same both with and without UTF-8 support
2156    means that the same test output works with both.
2158    38. There was a case of malloc(0) in the POSIX testing code in pcretest. Avoid
2159    calling malloc() with a zero argument.
2161    39. Change 25 above had to resort to a heavy-handed test for the .* anchoring
2162    optimization. I've improved things by keeping a bitmap of backreferences with
2163    numbers 1-31 so that if .* occurs inside capturing brackets that are not in
2164    fact referenced, the optimization can be applied. It is unlikely that a
2165    relevant occurrence of .* (i.e. one which might indicate anchoring or forcing
2166    the match to follow \n) will appear inside brackets with a number greater than
2167    31, but if it does, any back reference > 31 suppresses the optimization.
2169    40. Added a new compile-time option PCRE_NO_AUTO_CAPTURE. This has the effect
2170    of disabling numbered capturing parentheses. Any opening parenthesis that is
2171    not followed by ? behaves as if it were followed by ?: but named parentheses
2172    can still be used for capturing (and they will acquire numbers in the usual
2173    way).
2175    41. Redesigned the return codes from the match() function into yes/no/error so
2176    that errors can be passed back from deep inside the nested calls. A malloc
2177    failure while inside a recursive subpattern call now causes the
2178    PCRE_ERROR_NOMEMORY return instead of quietly going wrong.
2180    42. It is now possible to set a limit on the number of times the match()
2181    function is called in a call to pcre_exec(). This facility makes it possible to
2182    limit the amount of recursion and backtracking, though not in a directly
2183    obvious way, because the match() function is used in a number of different
2184    circumstances. The count starts from zero for each position in the subject
2185    string (for non-anchored patterns). The default limit is, for compatibility, a
2186    large number, namely 10 000 000. You can change this in two ways:
2188    (a) When configuring PCRE before making, you can use --with-match-limit=n
2189        to set a default value for the compiled library.
2191    (b) For each call to pcre_exec(), you can pass a pcre_extra block in which
2192        a different value is set. See 45 below.
2194    If the limit is exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT.
2196    43. Added a new function pcre_config(int, void *) to enable run-time extraction
2197    of things that can be changed at compile time. The first argument specifies
2198    what is wanted and the second points to where the information is to be placed.
2199    The current list of available information is:
2201      PCRE_CONFIG_UTF8
2203    The output is an integer that is set to one if UTF-8 support is available;
2204    otherwise it is set to zero.
2208    The output is an integer that it set to the value of the code that is used for
2209    newline. It is either LF (10) or CR (13).
2213    The output is an integer that contains the number of bytes used for internal
2214    linkage in compiled expressions. The value is 2, 3, or 4. See item 32 above.
2218    The output is an integer that contains the threshold above which the POSIX
2219    interface uses malloc() for output vectors. See item 31 above.
2223    The output is an unsigned integer that contains the default limit of the number
2224    of match() calls in a pcre_exec() execution. See 42 above.
2226    44. pcretest has been upgraded by the addition of the -C option. This causes it
2227    to extract all the available output from the new pcre_config() function, and to
2228    output it. The program then exits immediately.
2230    45. A need has arisen to pass over additional data with calls to pcre_exec() in
2231    order to support additional features. One way would have been to define
2232    pcre_exec2() (for example) with extra arguments, but this would not have been
2233    extensible, and would also have required all calls to the original function to
2234    be mapped to the new one. Instead, I have chosen to extend the mechanism that
2235    is used for passing in "extra" data from pcre_study().
2237    The pcre_extra structure is now exposed and defined in pcre.h. It currently
2238    contains the following fields:
2240      flags         a bitmap indicating which of the following fields are set
2241      study_data    opaque data from pcre_study()
2242      match_limit   a way of specifying a limit on match() calls for a specific
2243                      call to pcre_exec()
2244      callout_data  data for callouts (see 49 below)
2246    The flag bits are also defined in pcre.h, and are
2252    The pcre_study() function now returns one of these new pcre_extra blocks, with
2253    the actual study data pointed to by the study_data field, and the
2254    PCRE_EXTRA_STUDY_DATA flag set. This can be passed directly to pcre_exec() as
2255    before. That is, this change is entirely upwards-compatible and requires no
2256    change to existing code.
2258    If you want to pass in additional data to pcre_exec(), you can either place it
2259    in a pcre_extra block provided by pcre_study(), or create your own pcre_extra
2260    block.
2262    46. pcretest has been extended to test the PCRE_EXTRA_MATCH_LIMIT feature. If a
2263    data string contains the escape sequence \M, pcretest calls pcre_exec() several
2264    times with different match limits, until it finds the minimum value needed for
2265    pcre_exec() to complete. The value is then output. This can be instructive; for
2266    most simple matches the number is quite small, but for pathological cases it
2267    gets very large very quickly.
2269    47. There's a new option for pcre_fullinfo() called PCRE_INFO_STUDYSIZE. It
2270    returns the size of the data block pointed to by the study_data field in a
2271    pcre_extra block, that is, the value that was passed as the argument to
2272    pcre_malloc() when PCRE was getting memory in which to place the information
2273    created by pcre_study(). The fourth argument should point to a size_t variable.
2274    pcretest has been extended so that this information is shown after a successful
2275    pcre_study() call when information about the compiled regex is being displayed.
2277    48. Cosmetic change to Makefile: there's no need to have / after $(DESTDIR)
2278    because what follows is always an absolute path. (Later: it turns out that this
2279    is more than cosmetic for MinGW, because it doesn't like empty path
2280    components.)
2282    49. Some changes have been made to the callout feature (see 28 above):
2284    (i)  A callout function now has three choices for what it returns:
2286           0  =>  success, carry on matching
2287         > 0  =>  failure at this point, but backtrack if possible
2288         < 0  =>  serious error, return this value from pcre_exec()
2290         Negative values should normally be chosen from the set of PCRE_ERROR_xxx
2291         values. In particular, returning PCRE_ERROR_NOMATCH forces a standard
2292         "match failed" error. The error number PCRE_ERROR_CALLOUT is reserved for
2293         use by callout functions. It will never be used by PCRE itself.
2295    (ii) The pcre_extra structure (see 45 above) has a void * field called
2296         callout_data, with corresponding flag bit PCRE_EXTRA_CALLOUT_DATA. The
2297         pcre_callout_block structure has a field of the same name. The contents of
2298         the field passed in the pcre_extra structure are passed to the callout
2299         function in the corresponding field in the callout block. This makes it
2300         easier to use the same callout-containing regex from multiple threads. For
2301         testing, the pcretest program has a new data escape
2303           \C*n        pass the number n (may be negative) as callout_data
2305         If the callout function in pcretest receives a non-zero value as
2306         callout_data, it returns that value.
2308    50. Makefile wasn't handling CFLAGS properly when compiling dftables. Also,
2309    there were some redundant $(CFLAGS) in commands that are now specified as
2310    $(LINK), which already includes $(CFLAGS).
2312    51. Extensions to UTF-8 support are listed below. These all apply when (a) PCRE
2313    has been compiled with UTF-8 support *and* pcre_compile() has been compiled
2314    with the PCRE_UTF8 flag. Patterns that are compiled without that flag assume
2315    one-byte characters throughout. Note that case-insensitive matching applies
2316    only to characters whose values are less than 256. PCRE doesn't support the
2317    notion of cases for higher-valued characters.
2319    (i)   A character class whose characters are all within 0-255 is handled as
2320          a bit map, and the map is inverted for negative classes. Previously, a
2321          character > 255 always failed to match such a class; however it should
2322          match if the class was a negative one (e.g. [^ab]). This has been fixed.
2324    (ii)  A negated character class with a single character < 255 is coded as
2325          "not this character" (OP_NOT). This wasn't working properly when the test
2326          character was multibyte, either singly or repeated.
2328    (iii) Repeats of multibyte characters are now handled correctly in UTF-8
2329          mode, for example: \x{100}{2,3}.
2331    (iv)  The character escapes \b, \B, \d, \D, \s, \S, \w, and \W (either
2332          singly or repeated) now correctly test multibyte characters. However,
2333          PCRE doesn't recognize any characters with values greater than 255 as
2334          digits, spaces, or word characters. Such characters always match \D, \S,
2335          and \W, and never match \d, \s, or \w.
2337    (v)   Classes may now contain characters and character ranges with values
2338          greater than 255. For example: [ab\x{100}-\x{400}].
2340    (vi)  pcregrep now has a --utf-8 option (synonym -u) which makes it call
2341          PCRE in UTF-8 mode.
2343    52. The info request value PCRE_INFO_FIRSTCHAR has been renamed
2344    PCRE_INFO_FIRSTBYTE because it is a byte value. However, the old name is
2345    retained for backwards compatibility. (Note that LASTLITERAL is also a byte
2346    value.)
2348    53. The single man page has become too large. I have therefore split it up into
2349    a number of separate man pages. These also give rise to individual HTML pages;
2350    these are now put in a separate directory, and there is an index.html page that
2351    lists them all. Some hyperlinking between the pages has been installed.
2353    54. Added convenience functions for handling named capturing parentheses.
2355    55. Unknown escapes inside character classes (e.g. [\M]) and escapes that
2356    aren't interpreted therein (e.g. [\C]) are literals in Perl. This is now also
2357    true in PCRE, except when the PCRE_EXTENDED option is set, in which case they
2358    are faulted.
2360    56. Introduced HOST_CC and HOST_CFLAGS which can be set in the environment when
2361    calling configure. These values are used when compiling the dftables.c program
2362    which is run to generate the source of the default character tables. They
2363    default to the values of CC and CFLAGS. If you are cross-compiling PCRE,
2364    you will need to set these values.
2366    57. Updated the building process for Windows DLL, as provided by Fred Cox.
2369    Version 3.9 02-Jan-02
2370    ---------------------
2372    1. A bit of extraneous text had somehow crept into the pcregrep documentation.
2374    2. If --disable-static was given, the building process failed when trying to
2375    build pcretest and pcregrep. (For some reason it was using libtool to compile
2376    them, which is not right, as they aren't part of the library.)
2379    Version 3.8 18-Dec-01
2380    ---------------------
2382    1. The experimental UTF-8 code was completely screwed up. It was packing the
2383    bytes in the wrong order. How dumb can you get?
2386    Version 3.7 29-Oct-01
2387    ---------------------
2389    1. In updating pcretest to check change 1 of version 3.6, I screwed up.
2390    This caused pcretest, when used on the test data, to segfault. Unfortunately,
2391    this didn't happen under Solaris 8, where I normally test things.
2393    2. The Makefile had to be changed to make it work on BSD systems, where 'make'
2394    doesn't seem to recognize that ./xxx and xxx are the same file. (This entry
2395    isn't in ChangeLog distributed with 3.7 because I forgot when I hastily made
2396    this fix an hour or so after the initial 3.7 release.)
2399    Version 3.6 23-Oct-01
2400    ---------------------
2402    1. Crashed with /(sens|respons)e and \1ibility/ and "sense and sensibility" if
2403    offsets passed as NULL with zero offset count.
2405    2. The config.guess and config.sub files had not been updated when I moved to
2406    the latest autoconf.
2409    Version 3.5 15-Aug-01
2410    ---------------------
2412    1. Added some missing #if !defined NOPOSIX conditionals in pcretest.c that
2413    had been forgotten.
2415    2. By using declared but undefined structures, we can avoid using "void"
2416    definitions in pcre.h while keeping the internal definitions of the structures
2417    private.
2419    3. The distribution is now built using autoconf 2.50 and libtool 1.4. From a
2420    user point of view, this means that both static and shared libraries are built
2421    by default, but this can be individually controlled. More of the work of
2422    handling this static/shared cases is now inside libtool instead of PCRE's make
2423    file.
2425    4. The pcretest utility is now installed along with pcregrep because it is
2426    useful for users (to test regexs) and by doing this, it automatically gets
2427    relinked by libtool. The documentation has been turned into a man page, so
2428    there are now .1, .txt, and .html versions in /doc.
2430    5. Upgrades to pcregrep:
2431       (i)   Added long-form option names like gnu grep.
2432       (ii)  Added --help to list all options with an explanatory phrase.
2433       (iii) Added -r, --recursive to recurse into sub-directories.
2434       (iv)  Added -f, --file to read patterns from a file.
2436    6. pcre_exec() was referring to its "code" argument before testing that
2437    argument for NULL (and giving an error if it was NULL).
2439    7. Upgraded Makefile.in to allow for compiling in a different directory from
2440    the source directory.
2442    8. Tiny buglet in pcretest: when pcre_fullinfo() was called to retrieve the
2443    options bits, the pointer it was passed was to an int instead of to an unsigned
2444    long int. This mattered only on 64-bit systems.
2446    9. Fixed typo (3.4/1) in pcre.h again. Sigh. I had changed pcre.h (which is
2447    generated) instead of pcre.in, which it its source. Also made the same change
2448    in several of the .c files.
2450    10. A new release of gcc defines printf() as a macro, which broke pcretest
2451    because it had an ifdef in the middle of a string argument for printf(). Fixed
2452    by using separate calls to printf().
2454    11. Added --enable-newline-is-cr and --enable-newline-is-lf to the configure
2455    script, to force use of CR or LF instead of \n in the source. On non-Unix
2456    systems, the value can be set in config.h.
2458    12. The limit of 200 on non-capturing parentheses is a _nesting_ limit, not an
2459    absolute limit. Changed the text of the error message to make this clear, and
2460    likewise updated the man page.
2462    13. The limit of 99 on the number of capturing subpatterns has been removed.
2463    The new limit is 65535, which I hope will not be a "real" limit.
2466    Version 3.4 22-Aug-00
2467    ---------------------
2469    1. Fixed typo in pcre.h: unsigned const char * changed to const unsigned char *.
2471    2. Diagnose condition (?(0) as an error instead of crashing on matching.
2474    Version 3.3 01-Aug-00
2475    ---------------------
2477    1. If an octal character was given, but the value was greater than \377, it
2478    was not getting masked to the least significant bits, as documented. This could
2479    lead to crashes in some systems.
2481    2. Perl 5.6 (if not earlier versions) accepts classes like [a-\d] and treats
2482    the hyphen as a literal. PCRE used to give an error; it now behaves like Perl.
2484    3. Added the functions pcre_free_substring() and pcre_free_substring_list().
2485    These just pass their arguments on to (pcre_free)(), but they are provided
2486    because some uses of PCRE bind it to non-C systems that can call its functions,
2487    but cannot call free() or pcre_free() directly.
2489    4. Add "make test" as a synonym for "make check". Corrected some comments in
2490    the Makefile.
2492    5. Add $(DESTDIR)/ in front of all the paths in the "install" target in the
2493    Makefile.
2495    6. Changed the name of pgrep to pcregrep, because Solaris has introduced a
2496    command called pgrep for grepping around the active processes.
2498    7. Added the beginnings of support for UTF-8 character strings.
2500    8. Arranged for the Makefile to pass over the settings of CC, CFLAGS, and
2501    RANLIB to ./ltconfig so that they are used by libtool. I think these are all
2502    the relevant ones. (AR is not passed because ./ltconfig does its own figuring
2503    out for the ar command.)
2506    Version 3.2 12-May-00
2507    ---------------------
2509    This is purely a bug fixing release.
2511    1. If the pattern /((Z)+|A)*/ was matched agained ZABCDEFG it matched Z instead
2512    of ZA. This was just one example of several cases that could provoke this bug,
2513    which was introduced by change 9 of version 2.00. The code for breaking
2514    infinite loops after an iteration that matches an empty string was't working
2515    correctly.
2517    2. The pcretest program was not imitating Perl correctly for the pattern /a*/g
2518    when matched against abbab (for example). After matching an empty string, it
2519    wasn't forcing anchoring when setting PCRE_NOTEMPTY for the next attempt; this
2520    caused it to match further down the string than it should.
2522    3. The code contained an inclusion of sys/types.h. It isn't clear why this
2523    was there because it doesn't seem to be needed, and it causes trouble on some
2524    systems, as it is not a Standard C header. It has been removed.
2526    4. Made 4 silly changes to the source to avoid stupid compiler warnings that
2527    were reported on the Macintosh. The changes were from
2529      while ((c = *(++ptr)) != 0 && c != '\n');
2530    to
2531      while ((c = *(++ptr)) != 0 && c != '\n') ;
2533    Totally extraordinary, but if that's what it takes...
2535    5. PCRE is being used in one environment where neither memmove() nor bcopy() is
2536    available. Added HAVE_BCOPY and an autoconf test for it; if neither
2537    HAVE_MEMMOVE nor HAVE_BCOPY is set, use a built-in emulation function which
2538    assumes the way PCRE uses memmove() (always moving upwards).
2540    6. PCRE is being used in one environment where strchr() is not available. There
2541    was only one use in pcre.c, and writing it out to avoid strchr() probably gives
2542    faster code anyway.
2545    Version 3.1 09-Feb-00
2546    ---------------------
2548    The only change in this release is the fixing of some bugs in Makefile.in for
2549    the "install" target:
2551    (1) It was failing to install pcreposix.h.
2553    (2) It was overwriting the pcre.3 man page with the pcreposix.3 man page.
2556    Version 3.0 01-Feb-00
2557    ---------------------
2559  1. Add support for the /+ modifier to perltest (to output $` like it does in  1. Add support for the /+ modifier to perltest (to output $` like it does in
2560  pcretest).  pcretest).
# Line 23  captured string vector to pcre_exec(), b Line 2574  captured string vector to pcre_exec(), b
2574  required a bigger vector, with some working space on the end. This means that  required a bigger vector, with some working space on the end. This means that
2575  the POSIX wrapper now has to get and free some memory, and copy the results.  the POSIX wrapper now has to get and free some memory, and copy the results.
2577    6. Added some simple autoconf support, placing the test data and the
2578    documentation in separate directories, re-organizing some of the
2579    information files, and making it build pcre-config (a GNU standard). Also added
2580    libtool support for building PCRE as a shared library, which is now the
2581    default.
2583    7. Got rid of the leading zero in the definition of PCRE_MINOR because 08 and
2584    09 are not valid octal constants. Single digits will be used for minor values
2585    less than 10.
2587    8. Defined REG_EXTENDED and REG_NOSUB as zero in the POSIX header, so that
2588    existing programs that set these in the POSIX interface can use PCRE without
2589    modification.
2591    9. Added a new function, pcre_fullinfo() with an extensible interface. It can
2592    return all that pcre_info() returns, plus additional data. The pcre_info()
2593    function is retained for compatibility, but is considered to be obsolete.
2595    10. Added experimental recursion feature (?R) to handle one common case that
2596    Perl 5.6 will be able to do with (?p{...}).
2598    11. Added support for POSIX character classes like [:alpha:], which Perl is
2599    adopting.
2602  Version 2.08 31-Aug-99  Version 2.08 31-Aug-99
2603  ----------------------  ----------------------

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