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revision 49 by nigel, Sat Feb 24 21:39:33 2007 UTC revision 295 by ph10, Mon Dec 31 17:00:24 2007 UTC
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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
4    Version 7.5 31-Dec-07
5    ---------------------
7    1.  Applied a patch from Craig: "This patch makes it possible to 'ignore'
8        values in parens when parsing an RE using the C++ wrapper."
10    2.  Negative specials like \S did not work in character classes in UTF-8 mode.
11        Characters greater than 255 were excluded from the class instead of being
12        included.
14    3.  The same bug as (2) above applied to negated POSIX classes such as
15        [:^space:].
17    4.  PCRECPP_STATIC was referenced in pcrecpp_internal.h, but nowhere was it
18        defined or documented. It seems to have been a typo for PCRE_STATIC, so
19        I have changed it.
21    5.  The construct (?&) was not diagnosed as a syntax error (it referenced the
22        first named subpattern) and a construct such as (?&a) would reference the
23        first named subpattern whose name started with "a" (in other words, the
24        length check was missing). Both these problems are fixed. "Subpattern name
25        expected" is now given for (?&) (a zero-length name), and this patch also
26        makes it give the same error for \k'' (previously it complained that that
27        was a reference to a non-existent subpattern).
29    6.  The erroneous patterns (?+-a) and (?-+a) give different error messages;
30        this is right because (?- can be followed by option settings as well as by
31        digits. I have, however, made the messages clearer.
33    7.  Patterns such as (?(1)a|b) (a pattern that contains fewer subpatterns
34        than the number used in the conditional) now cause a compile-time error.
35        This is actually not compatible with Perl, which accepts such patterns, but
36        treats the conditional as always being FALSE (as PCRE used to), but it
37        seems to me that giving a diagnostic is better.
39    8.  Change "alphameric" to the more common word "alphanumeric" in comments
40        and messages.
42    9.  Fix two occurrences of "backslash" in comments that should have been
43        "backspace".
45    10. Remove two redundant lines of code that can never be obeyed (their function
46        was moved elsewhere).
48    11. The program that makes PCRE's Unicode character property table had a bug
49        which caused it to generate incorrect table entries for sequences of
50        characters that have the same character type, but are in different scripts.
51        It amalgamated them into a single range, with the script of the first of
52        them. In other words, some characters were in the wrong script. There were
53        thirteen such cases, affecting characters in the following ranges:
55          U+002b0 - U+002c1
56          U+0060c - U+0060d
57          U+0061e - U+00612
58          U+0064b - U+0065e
59          U+0074d - U+0076d
60          U+01800 - U+01805
61          U+01d00 - U+01d77
62          U+01d9b - U+01dbf
63          U+0200b - U+0200f
64          U+030fc - U+030fe
65          U+03260 - U+0327f
66          U+0fb46 - U+0fbb1
67          U+10450 - U+1049d
69    12. The -o option (show only the matching part of a line) for pcregrep was not
70        compatible with GNU grep in that, if there was more than one match in a
71        line, it showed only the first of them. It now behaves in the same way as
72        GNU grep.
74    13. If the -o and -v options were combined for pcregrep, it printed a blank
75        line for every non-matching line. GNU grep prints nothing, and pcregrep now
76        does the same. The return code can be used to tell if there were any
77        non-matching lines.
79    14. 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.
104    21. Several CMake things:
106        (1) Arranged that, when cmake is used on Unix, the libraries end up with
107            the names libpcre and libpcreposix, not just pcre and pcreposix.
109        (2) The above change means that pcretest and pcregrep are now correctly
110            linked with the newly-built libraries, not previously installed ones.
114    22. In UTF-8 mode, with newline set to "any", a pattern such as .*a.*=.b.*
115        crashed when matching a string such as a\x{2029}b (note that \x{2029} is a
116        UTF-8 newline character). The key issue is that the pattern starts .*;
117        this means that the match must be either at the beginning, or after a
118        newline. The bug was in the code for advancing after a failed match and
119        checking that the new position followed a newline. It was not taking
120        account of UTF-8 characters correctly.
122    23. PCRE was behaving differently from Perl in the way it recognized POSIX
123        character classes. PCRE was not treating the sequence [:...:] as a
124        character class unless the ... were all letters. Perl, however, seems to
125        allow any characters between [: and :], though of course it rejects as
126        unknown any "names" that contain non-letters, because all the known class
127        names consist only of letters. Thus, Perl gives an error for [[:1234:]],
128        for example, whereas PCRE did not - it did not recognize a POSIX character
129        class. This seemed a bit dangerous, so the code has been changed to be
130        closer to Perl. The behaviour is not identical to Perl, because PCRE will
131        diagnose an unknown class for, for example, [[:l\ower:]] where Perl will
132        treat it as [[:lower:]]. However, PCRE does now give "unknown" errors where
133        Perl does, and where it didn't before.
136    Version 7.4 21-Sep-07
137    ---------------------
139    1.  Change 7.3/28 was implemented for classes by looking at the bitmap. This
140        means that a class such as [\s] counted as "explicit reference to CR or
141        LF". That isn't really right - the whole point of the change was to try to
142        help when there was an actual mention of one of the two characters. So now
143        the change happens only if \r or \n (or a literal CR or LF) character is
144        encountered.
146    2.  The 32-bit options word was also used for 6 internal flags, but the numbers
147        of both had grown to the point where there were only 3 bits left.
148        Fortunately, there was spare space in the data structure, and so I have
149        moved the internal flags into a new 16-bit field to free up more option
150        bits.
152    3.  The appearance of (?J) at the start of a pattern set the DUPNAMES option,
153        but did not set the internal JCHANGED flag - either of these is enough to
154        control the way the "get" function works - but the PCRE_INFO_JCHANGED
155        facility is supposed to tell if (?J) was ever used, so now (?J) at the
156        start sets both bits.
158    4.  Added options (at build time, compile time, exec time) to change \R from
159        matching any Unicode line ending sequence to just matching CR, LF, or CRLF.
161    5.  doc/pcresyntax.html was missing from the distribution.
163    6.  Put back the definition of PCRE_ERROR_NULLWSLIMIT, for backward
164        compatibility, even though it is no longer used.
166    7.  Added macro for snprintf to pcrecpp_unittest.cc and also for strtoll and
167        strtoull to pcrecpp.cc to select the available functions in WIN32 when the
168        windows.h file is present (where different names are used). [This was
169        reversed later after testing - see 16 below.]
171    8.  Changed all #include <config.h> to #include "config.h". There were also
172        some further <pcre.h> cases that I changed to "pcre.h".
174    9.  When pcregrep was used with the --colour option, it missed the line ending
175        sequence off the lines that it output.
177    10. It was pointed out to me that arrays of string pointers cause lots of
178        relocations when a shared library is dynamically loaded. A technique of
179        using a single long string with a table of offsets can drastically reduce
180        these. I have refactored PCRE in four places to do this. The result is
181        dramatic:
183          Originally:                          290
184          After changing UCP table:            187
185          After changing error message table:   43
186          After changing table of "verbs"       36
187          After changing table of Posix names   22
189        Thanks to the folks working on Gregex for glib for this insight.
191    11. --disable-stack-for-recursion caused compiling to fail unless -enable-
192        unicode-properties was also set.
194    12. Updated the tests so that they work when \R is defaulted to ANYCRLF.
196    13. Added checks for ANY and ANYCRLF to pcrecpp.cc where it previously
197        checked only for CRLF.
199    14. Added casts to pcretest.c to avoid compiler warnings.
201    15. Added Craig's patch to various pcrecpp modules to avoid compiler warnings.
203    16. Added Craig's patch to remove the WINDOWS_H tests, that were not working,
204        and instead check for _strtoi64 explicitly, and avoid the use of snprintf()
205        entirely. This removes changes made in 7 above.
207    17. The CMake files have been updated, and there is now more information about
208        building with CMake in the NON-UNIX-USE document.
211    Version 7.3 28-Aug-07
212    ---------------------
214     1. In the rejigging of the build system that eventually resulted in 7.1, the
215        line "#include <pcre.h>" was included in pcre_internal.h. The use of angle
216        brackets there is not right, since it causes compilers to look for an
217        installed pcre.h, not the version that is in the source that is being
218        compiled (which of course may be different). I have changed it back to:
220          #include "pcre.h"
222        I have a vague recollection that the change was concerned with compiling in
223        different directories, but in the new build system, that is taken care of
224        by the VPATH setting the Makefile.
226     2. The pattern .*$ when run in not-DOTALL UTF-8 mode with newline=any failed
227        when the subject happened to end in the byte 0x85 (e.g. if the last
228        character was \x{1ec5}). *Character* 0x85 is one of the "any" newline
229        characters but of course it shouldn't be taken as a newline when it is part
230        of another character. The bug was that, for an unlimited repeat of . in
231        not-DOTALL UTF-8 mode, PCRE was advancing by bytes rather than by
232        characters when looking for a newline.
234     3. A small performance improvement in the DOTALL UTF-8 mode .* case.
236     4. Debugging: adjusted the names of opcodes for different kinds of parentheses
237        in debug output.
239     5. Arrange to use "%I64d" instead of "%lld" and "%I64u" instead of "%llu" for
240        long printing in the pcrecpp unittest when running under MinGW.
242     6. ESC_K was left out of the EBCDIC table.
244     7. Change 7.0/38 introduced a new limit on the number of nested non-capturing
245        parentheses; I made it 1000, which seemed large enough. Unfortunately, the
246        limit also applies to "virtual nesting" when a pattern is recursive, and in
247        this case 1000 isn't so big. I have been able to remove this limit at the
248        expense of backing off one optimization in certain circumstances. Normally,
249        when pcre_exec() would call its internal match() function recursively and
250        immediately return the result unconditionally, it uses a "tail recursion"
251        feature to save stack. However, when a subpattern that can match an empty
252        string has an unlimited repetition quantifier, it no longer makes this
253        optimization. That gives it a stack frame in which to save the data for
254        checking that an empty string has been matched. Previously this was taken
255        from the 1000-entry workspace that had been reserved. So now there is no
256        explicit limit, but more stack is used.
258     8. Applied Daniel's patches to solve problems with the import/export magic
259        syntax that is required for Windows, and which was going wrong for the
260        pcreposix and pcrecpp parts of the library. These were overlooked when this
261        problem was solved for the main library.
263     9. There were some crude static tests to avoid integer overflow when computing
264        the size of patterns that contain repeated groups with explicit upper
265        limits. As the maximum quantifier is 65535, the maximum group length was
266        set at 30,000 so that the product of these two numbers did not overflow a
267        32-bit integer. However, it turns out that people want to use groups that
268        are longer than 30,000 bytes (though not repeat them that many times).
269        Change 7.0/17 (the refactoring of the way the pattern size is computed) has
270        made it possible to implement the integer overflow checks in a much more
271        dynamic way, which I have now done. The artificial limitation on group
272        length has been removed - we now have only the limit on the total length of
273        the compiled pattern, which depends on the LINK_SIZE setting.
275    10. Fixed a bug in the documentation for get/copy named substring when
276        duplicate names are permitted. If none of the named substrings are set, the
277        functions return PCRE_ERROR_NOSUBSTRING (7); the doc said they returned an
278        empty string.
280    11. Because Perl interprets \Q...\E at a high level, and ignores orphan \E
281        instances, patterns such as [\Q\E] or [\E] or even [^\E] cause an error,
282        because the ] is interpreted as the first data character and the
283        terminating ] is not found. PCRE has been made compatible with Perl in this
284        regard. Previously, it interpreted [\Q\E] as an empty class, and [\E] could
285        cause memory overwriting.
287    10. Like Perl, PCRE automatically breaks an unlimited repeat after an empty
288        string has been matched (to stop an infinite loop). It was not recognizing
289        a conditional subpattern that could match an empty string if that
290        subpattern was within another subpattern. For example, it looped when
291        trying to match  (((?(1)X|))*)  but it was OK with  ((?(1)X|)*)  where the
292        condition was not nested. This bug has been fixed.
294    12. A pattern like \X?\d or \P{L}?\d in non-UTF-8 mode could cause a backtrack
295        past the start of the subject in the presence of bytes with the top bit
296        set, for example "\x8aBCD".
298    13. Added Perl 5.10 experimental backtracking controls (*FAIL), (*F), (*PRUNE),
299        (*SKIP), (*THEN), (*COMMIT), and (*ACCEPT).
301    14. Optimized (?!) to (*FAIL).
303    15. Updated the test for a valid UTF-8 string to conform to the later RFC 3629.
304        This restricts code points to be within the range 0 to 0x10FFFF, excluding
305        the "low surrogate" sequence 0xD800 to 0xDFFF. Previously, PCRE allowed the
306        full range 0 to 0x7FFFFFFF, as defined by RFC 2279. Internally, it still
307        does: it's just the validity check that is more restrictive.
309    16. Inserted checks for integer overflows during escape sequence (backslash)
310        processing, and also fixed erroneous offset values for syntax errors during
311        backslash processing.
313    17. Fixed another case of looking too far back in non-UTF-8 mode (cf 12 above)
314        for patterns like [\PPP\x8a]{1,}\x80 with the subject "A\x80".
316    18. An unterminated class in a pattern like (?1)\c[ with a "forward reference"
317        caused an overrun.
319    19. A pattern like (?:[\PPa*]*){8,} which had an "extended class" (one with
320        something other than just ASCII characters) inside a group that had an
321        unlimited repeat caused a loop at compile time (while checking to see
322        whether the group could match an empty string).
324    20. Debugging a pattern containing \p or \P could cause a crash. For example,
325        [\P{Any}] did so. (Error in the code for printing property names.)
327    21. An orphan \E inside a character class could cause a crash.
329    22. A repeated capturing bracket such as (A)? could cause a wild memory
330        reference during compilation.
332    23. There are several functions in pcre_compile() that scan along a compiled
333        expression for various reasons (e.g. to see if it's fixed length for look
334        behind). There were bugs in these functions when a repeated \p or \P was
335        present in the pattern. These operators have additional parameters compared
336        with \d, etc, and these were not being taken into account when moving along
337        the compiled data. Specifically:
339        (a) A item such as \p{Yi}{3} in a lookbehind was not treated as fixed
340            length.
342        (b) An item such as \pL+ within a repeated group could cause crashes or
343            loops.
345        (c) A pattern such as \p{Yi}+(\P{Yi}+)(?1) could give an incorrect
346            "reference to non-existent subpattern" error.
348        (d) A pattern like (\P{Yi}{2}\277)? could loop at compile time.
350    24. A repeated \S or \W in UTF-8 mode could give wrong answers when multibyte
351        characters were involved (for example /\S{2}/8g with "A\x{a3}BC").
353    25. Using pcregrep in multiline, inverted mode (-Mv) caused it to loop.
355    26. Patterns such as [\P{Yi}A] which include \p or \P and just one other
356        character were causing crashes (broken optimization).
358    27. Patterns such as (\P{Yi}*\277)* (group with possible zero repeat containing
359        \p or \P) caused a compile-time loop.
361    28. More problems have arisen in unanchored patterns when CRLF is a valid line
362        break. For example, the unstudied pattern [\r\n]A does not match the string
363        "\r\nA" because change 7.0/46 below moves the current point on by two
364        characters after failing to match at the start. However, the pattern \nA
365        *does* match, because it doesn't start till \n, and if [\r\n]A is studied,
366        the same is true. There doesn't seem any very clean way out of this, but
367        what I have chosen to do makes the common cases work: PCRE now takes note
368        of whether there can be an explicit match for \r or \n anywhere in the
369        pattern, and if so, 7.0/46 no longer applies. As part of this change,
370        there's a new PCRE_INFO_HASCRORLF option for finding out whether a compiled
371        pattern has explicit CR or LF references.
373    29. Added (*CR) etc for changing newline setting at start of pattern.
376    Version 7.2 19-Jun-07
377    ---------------------
379     1. If the fr_FR locale cannot be found for test 3, try the "french" locale,
380        which is apparently normally available under Windows.
382     2. Re-jig the pcregrep tests with different newline settings in an attempt
383        to make them independent of the local environment's newline setting.
385     3. Add code to configure.ac to remove -g from the CFLAGS default settings.
387     4. Some of the "internals" tests were previously cut out when the link size
388        was not 2, because the output contained actual offsets. The recent new
389        "Z" feature of pcretest means that these can be cut out, making the tests
390        usable with all link sizes.
392     5. Implemented Stan Switzer's goto replacement for longjmp() when not using
393        stack recursion. This gives a massive performance boost under BSD, but just
394        a small improvement under Linux. However, it saves one field in the frame
395        in all cases.
397     6. Added more features from the forthcoming Perl 5.10:
399        (a) (?-n) (where n is a string of digits) is a relative subroutine or
400            recursion call. It refers to the nth most recently opened parentheses.
402        (b) (?+n) is also a relative subroutine call; it refers to the nth next
403            to be opened parentheses.
405        (c) Conditions that refer to capturing parentheses can be specified
406            relatively, for example, (?(-2)... or (?(+3)...
408        (d) \K resets the start of the current match so that everything before
409            is not part of it.
411        (e) \k{name} is synonymous with \k<name> and \k'name' (.NET compatible).
413        (f) \g{name} is another synonym - part of Perl 5.10's unification of
414            reference syntax.
416        (g) (?| introduces a group in which the numbering of parentheses in each
417            alternative starts with the same number.
419        (h) \h, \H, \v, and \V match horizontal and vertical whitespace.
421     7. Added two new calls to pcre_fullinfo(): PCRE_INFO_OKPARTIAL and
424     8. A pattern such as  (.*(.)?)*  caused pcre_exec() to fail by either not
425        terminating or by crashing. Diagnosed by Viktor Griph; it was in the code
426        for detecting groups that can match an empty string.
428     9. A pattern with a very large number of alternatives (more than several
429        hundred) was running out of internal workspace during the pre-compile
430        phase, where pcre_compile() figures out how much memory will be needed. A
431        bit of new cunning has reduced the workspace needed for groups with
432        alternatives. The 1000-alternative test pattern now uses 12 bytes of
433        workspace instead of running out of the 4096 that are available.
435    10. Inserted some missing (unsigned int) casts to get rid of compiler warnings.
437    11. Applied patch from Google to remove an optimization that didn't quite work.
438        The report of the bug said:
440          pcrecpp::RE("a*").FullMatch("aaa") matches, while
441          pcrecpp::RE("a*?").FullMatch("aaa") does not, and
442          pcrecpp::RE("a*?\\z").FullMatch("aaa") does again.
444    12. If \p or \P was used in non-UTF-8 mode on a character greater than 127
445        it matched the wrong number of bytes.
448    Version 7.1 24-Apr-07
449    ---------------------
451     1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
452        that is more "standard", making use of automake and other Autotools. There
453        is some re-arrangement of the files and adjustment of comments consequent
454        on this.
456     2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
457        for recursive directory scanning broke on some systems because the files
458        are not scanned in any specific order and on different systems the order
459        was different. A call to "sort" has been inserted into RunGrepTest for the
460        approprate test as a short-term fix. In the longer term there may be an
461        alternative.
463     3. I had an email from Eric Raymond about problems translating some of PCRE's
464        man pages to HTML (despite the fact that I distribute HTML pages, some
465        people do their own conversions for various reasons). The problems
466        concerned the use of low-level troff macros .br and .in. I have therefore
467        removed all such uses from the man pages (some were redundant, some could
468        be replaced by .nf/.fi pairs). The 132html script that I use to generate
469        HTML has been updated to handle .nf/.fi and to complain if it encounters
470        .br or .in.
472     4. Updated comments in configure.ac that get placed in config.h.in and also
473        arranged for config.h to be included in the distribution, with the name
474        config.h.generic, for the benefit of those who have to compile without
475        Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
477     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
478        Weber: (1) pcre_internal.h was missing some function renames; (2) updated
479        makevp.bat for the current PCRE, using the additional files
480        makevp_c.txt, makevp_l.txt, and pcregexp.pas.
482     6. A Windows user reported a minor discrepancy with test 2, which turned out
483        to be caused by a trailing space on an input line that had got lost in his
484        copy. The trailing space was an accident, so I've just removed it.
486     7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
487        that is needed.
489     8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
490        as "const" (a) because they are and (b) because it helps the PHP
491        maintainers who have recently made a script to detect big data structures
492        in the php code that should be moved to the .rodata section. I remembered
493        to update Builducptable as well, so it won't revert if ucptable.h is ever
494        re-created.
496     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
497        pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
498        order to be able to cut out the UTF-8 tables in the latter when UTF-8
499        support is not required. This saves 1.5-2K of code, which is important in
500        some applications.
502        Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
503        so as not to refer to the tables, even though these functions will never be
504        called when UTF-8 support is disabled. Otherwise there are problems with a
505        shared library.
507    10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
509        (a) It was defining its arguments as char * instead of void *.
511        (b) It was assuming that all moves were upwards in memory; this was true
512            a long time ago when I wrote it, but is no longer the case.
514        The emulated memove() is provided for those environments that have neither
515        memmove() nor bcopy(). I didn't think anyone used it these days, but that
516        is clearly not the case, as these two bugs were recently reported.
518    11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
519        and Detrail to create the HTML documentation, the .txt form of the man
520        pages, and it removes trailing spaces from listed files. It also creates
521        pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
522        case, it wraps all the #defines with #ifndefs. This script should be run
523        before "make dist".
525    12. Fixed two fairly obscure bugs concerned with quantified caseless matching
526        with Unicode property support.
528        (a) For a maximizing quantifier, if the two different cases of the
529            character were of different lengths in their UTF-8 codings (there are
530            some cases like this - I found 11), and the matching function had to
531            back up over a mixture of the two cases, it incorrectly assumed they
532            were both the same length.
534        (b) When PCRE was configured to use the heap rather than the stack for
535            recursion during matching, it was not correctly preserving the data for
536            the other case of a UTF-8 character when checking ahead for a match
537            while processing a minimizing repeat. If the check also involved
538            matching a wide character, but failed, corruption could cause an
539            erroneous result when trying to check for a repeat of the original
540            character.
542    13. Some tidying changes to the testing mechanism:
544        (a) The RunTest script now detects the internal link size and whether there
545            is UTF-8 and UCP support by running ./pcretest -C instead of relying on
546            values substituted by "configure". (The RunGrepTest script already did
547            this for UTF-8.) The configure.ac script no longer substitutes the
548            relevant variables.
550        (b) The debugging options /B and /D in pcretest show the compiled bytecode
551            with length and offset values. This means that the output is different
552            for different internal link sizes. Test 2 is skipped for link sizes
553            other than 2 because of this, bypassing the problem. Unfortunately,
554            there was also a test in test 3 (the locale tests) that used /B and
555            failed for link sizes other than 2. Rather than cut the whole test out,
556            I have added a new /Z option to pcretest that replaces the length and
557            offset values with spaces. This is now used to make test 3 independent
558            of link size. (Test 2 will be tidied up later.)
560    14. If erroroffset was passed as NULL to pcre_compile, it provoked a
561        segmentation fault instead of returning the appropriate error message.
563    15. In multiline mode when the newline sequence was set to "any", the pattern
564        ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
565        This doesn't seem right; it now treats the CRLF combination as the line
566        ending, and so does not match in that case. It's only a pattern such as ^$
567        that would hit this one: something like ^ABC$ would have failed after \r
568        and then tried again after \r\n.
570    16. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
571        in an attempt to make files that differ only in their line terminators
572        compare equal. This works on Linux.
574    17. Under certain error circumstances pcregrep might try to free random memory
575        as it exited. This is now fixed, thanks to valgrind.
577    19. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
578        "abc\r\n\r\n", it found an unwanted second match after the second \r. This
579        was because its rules for how to advance for /g after matching an empty
580        string at the end of a line did not allow for this case. They now check for
581        it specially.
583    20. pcretest is supposed to handle patterns and data of any length, by
584        extending its buffers when necessary. It was getting this wrong when the
585        buffer for a data line had to be extended.
587    21. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or
588        CRLF as a newline sequence.
590    22. Code for handling Unicode properties in pcre_dfa_exec() wasn't being cut
591        out by #ifdef SUPPORT_UCP. This did no harm, as it could never be used, but
592        I have nevertheless tidied it up.
594    23. Added some casts to kill warnings from HP-UX ia64 compiler.
596    24. Added a man page for pcre-config.
599    Version 7.0 19-Dec-06
600    ---------------------
602     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
603        moving to gcc 4.1.1.
605     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
606        sys/time.h, which is documented as needed for this function. It doesn't
607        seem to matter on Linux, but it showed up on some releases of OS X.
609     3. It seems that there are systems where bytes whose values are greater than
610        127 match isprint() in the "C" locale. The "C" locale should be the
611        default when a C program starts up. In most systems, only ASCII printing
612        characters match isprint(). This difference caused the output from pcretest
613        to vary, making some of the tests fail. I have changed pcretest so that:
615        (a) When it is outputting text in the compiled version of a pattern, bytes
616            other than 32-126 are always shown as hex escapes.
618        (b) When it is outputting text that is a matched part of a subject string,
619            it does the same, unless a different locale has been set for the match
620            (using the /L modifier). In this case, it uses isprint() to decide.
622     4. Fixed a major bug that caused incorrect computation of the amount of memory
623        required for a compiled pattern when options that changed within the
624        pattern affected the logic of the preliminary scan that determines the
625        length. The relevant options are -x, and -i in UTF-8 mode. The result was
626        that the computed length was too small. The symptoms of this bug were
627        either the PCRE error "internal error: code overflow" from pcre_compile(),
628        or a glibc crash with a message such as "pcretest: free(): invalid next
629        size (fast)". Examples of patterns that provoked this bug (shown in
630        pcretest format) are:
632          /(?-x: )/x
633          /(?x)(?-x: \s*#\s*)/
634          /((?i)[\x{c0}])/8
635          /(?i:[\x{c0}])/8
637        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
638        is now done differently.
640     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
641        wrapper classes; (b) implement a new function in the C++ scanner that is
642        more efficient than the old way of doing things because it avoids levels of
643        recursion in the regex matching; (c) add a paragraph to the documentation
644        for the FullMatch() function.
646     6. The escape sequence \n was being treated as whatever was defined as
647        "newline". Not only was this contrary to the documentation, which states
648        that \n is character 10 (hex 0A), but it also went horribly wrong when
649        "newline" was defined as CRLF. This has been fixed.
651     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
652        was being set to -1 for the "end of line" case (supposedly a value that no
653        character can have). Though this value is never used (the check for end of
654        line is "zero bytes in current character"), it caused compiler complaints.
655        I've changed it to 0xffffffff.
657     8. In pcre_version.c, the version string was being built by a sequence of
658        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
659        string (as it is for production releases) called a macro with an empty
660        argument. The C standard says the result of this is undefined. The gcc
661        compiler treats it as an empty string (which was what was wanted) but it is
662        reported that Visual C gives an error. The source has been hacked around to
663        avoid this problem.
665     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
666        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
667        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
668        of them did).
670    10. Originally, pcretest opened its input and output without "b"; then I was
671        told that "b" was needed in some environments, so it was added for release
672        5.0 to both the input and output. (It makes no difference on Unix-like
673        systems.) Later I was told that it is wrong for the input on Windows. I've
674        now abstracted the modes into two macros, to make it easier to fiddle with
675        them, and removed "b" from the input mode under Windows.
677    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
679    12. Added -help and --help to pcretest as an official way of being reminded
680        of the options.
682    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
683        and pcrecpp.cc because they annoy compilers at high warning levels.
685    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
687    15. Fixed an occurrence of == in configure.ac that should have been = (shell
688        scripts are not C programs :-) and which was not noticed because it works
689        on Linux.
691    16. pcretest is supposed to handle any length of pattern and data line (as one
692        line or as a continued sequence of lines) by extending its input buffer if
693        necessary. This feature was broken for very long pattern lines, leading to
694        a string of junk being passed to pcre_compile() if the pattern was longer
695        than about 50K.
697    17. I have done a major re-factoring of the way pcre_compile() computes the
698        amount of memory needed for a compiled pattern. Previously, there was code
699        that made a preliminary scan of the pattern in order to do this. That was
700        OK when PCRE was new, but as the facilities have expanded, it has become
701        harder and harder to keep it in step with the real compile phase, and there
702        have been a number of bugs (see for example, 4 above). I have now found a
703        cunning way of running the real compile function in a "fake" mode that
704        enables it to compute how much memory it would need, while actually only
705        ever using a few hundred bytes of working memory and without too many
706        tests of the mode. This should make future maintenance and development
707        easier. A side effect of this work is that the limit of 200 on the nesting
708        depth of parentheses has been removed (though this was never a serious
709        limitation, I suspect). However, there is a downside: pcre_compile() now
710        runs more slowly than before (30% or more, depending on the pattern). I
711        hope this isn't a big issue. There is no effect on runtime performance.
713    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
714        newline (only possible for the last line of a file) and it was a
715        pattern that set a locale (followed by /Lsomething), pcretest crashed.
717    19. Added additional timing features to pcretest. (1) The -tm option now times
718        matching only, not compiling. (2) Both -t and -tm can be followed, as a
719        separate command line item, by a number that specifies the number of
720        repeats to use when timing. The default is 50000; this gives better
721        precision, but takes uncomfortably long for very large patterns.
723    20. Extended pcre_study() to be more clever in cases where a branch of a
724        subpattern has no definite first character. For example, (a*|b*)[cd] would
725        previously give no result from pcre_study(). Now it recognizes that the
726        first character must be a, b, c, or d.
728    21. There was an incorrect error "recursive call could loop indefinitely" if
729        a subpattern (or the entire pattern) that was being tested for matching an
730        empty string contained only one non-empty item after a nested subpattern.
731        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
732        incorrectly, because the \d was being skipped in the check.
734    22. The pcretest program now has a new pattern option /B and a command line
735        option -b, which is equivalent to adding /B to every pattern. This causes
736        it to show the compiled bytecode, without the additional information that
737        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
738        is the same as /B/I).
740    23. A new optimization is now able automatically to treat some sequences such
741        as a*b as a*+b. More specifically, if something simple (such as a character
742        or a simple class like \d) has an unlimited quantifier, and is followed by
743        something that cannot possibly match the quantified thing, the quantifier
744        is automatically "possessified".
746    24. A recursive reference to a subpattern whose number was greater than 39
747        went wrong under certain circumstances in UTF-8 mode. This bug could also
748        have affected the operation of pcre_study().
750    25. Realized that a little bit of performance could be had by replacing
751        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
753    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
755    27. Possessive quantifiers such as a++ were previously implemented by turning
756        them into atomic groups such as ($>a+). Now they have their own opcodes,
757        which improves performance. This includes the automatically created ones
758        from 23 above.
760    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
761        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
762        the first matched character to be a colon. This applied both to named and
763        numbered groups.
765    29. The ucpinternal.h header file was missing its idempotency #ifdef.
767    30. I was sent a "project" file called libpcre.a.dev which I understand makes
768        building PCRE on Windows easier, so I have included it in the distribution.
770    31. There is now a check in pcretest against a ridiculously large number being
771        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
772        loop, the loop is abandoned.
774    32. Forward references to subpatterns in conditions such as (?(2)...) where
775        subpattern 2 is defined later cause pcre_compile() to search forwards in
776        the pattern for the relevant set of parentheses. This search went wrong
777        when there were unescaped parentheses in a character class, parentheses
778        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
780    33. "Subroutine" calls and backreferences were previously restricted to
781        referencing subpatterns earlier in the regex. This restriction has now
782        been removed.
784    34. Added a number of extra features that are going to be in Perl 5.10. On the
785        whole, these are just syntactic alternatives for features that PCRE had
786        previously implemented using the Python syntax or my own invention. The
787        other formats are all retained for compatibility.
789        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
790            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
791            also .NET compatible.
793        (b) A recursion or subroutine call to a named group can now be defined as
794            (?&name) as well as (?P>name).
796        (c) A backreference to a named group can now be defined as \k<name> or
797            \k'name' as well as (?P=name). The new forms, as well as being in Perl
798            5.10, are also .NET compatible.
800        (d) A conditional reference to a named group can now use the syntax
801            (?(<name>) or (?('name') as well as (?(name).
803        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
804            groups (named and numbered) that are never evaluated inline, but can be
805            called as "subroutines" from elsewhere. In effect, the DEFINE condition
806            is always false. There may be only one alternative in such a group.
808        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
809            as the simple (?(R). The condition is true only if the most recent
810            recursion is that of the given number or name. It does not search out
811            through the entire recursion stack.
813        (g) The escape \gN or \g{N} has been added, where N is a positive or
814            negative number, specifying an absolute or relative reference.
816    35. Tidied to get rid of some further signed/unsigned compiler warnings and
817        some "unreachable code" warnings.
819    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
820        things, this adds five new scripts.
822    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
823        There were also incompatibilities regarding the handling of \Q..\E inside
824        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
825        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
827    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
828        matches an empty string, and forcibly breaks the loop. There were bugs in
829        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
830        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
831        separate and independent bugs (that affected different cases) have been
832        fixed.
834    39. Refactored the code to abolish the use of different opcodes for small
835        capturing bracket numbers. This is a tidy that I avoided doing when I
836        removed the limit on the number of capturing brackets for 3.5 back in 2001.
837        The new approach is not only tidier, it makes it possible to reduce the
838        memory needed to fix the previous bug (38).
840    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
841        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
842        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
843        mode.
845    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
846        report.
848    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
849        copy construction and assignment in the C++ wrapper.
851    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
852        couple of bugs that could have given wrong results in the "--newline=crlf"
853        case.
855    44. Added a number of casts and did some reorganization of signed/unsigned int
856        variables following suggestions from Dair Grant. Also renamed the variable
857        "this" as "item" because it is a C++ keyword.
859    45. Arranged for dftables to add
861          #include "pcre_internal.h"
863        to pcre_chartables.c because without it, gcc 4.x may remove the array
864        definition from the final binary if PCRE is built into a static library and
865        dead code stripping is activated.
867    46. For an unanchored pattern, if a match attempt fails at the start of a
868        newline sequence, and the newline setting is CRLF or ANY, and the next two
869        characters are CRLF, advance by two characters instead of one.
872    Version 6.7 04-Jul-06
873    ---------------------
875     1. In order to handle tests when input lines are enormously long, pcretest has
876        been re-factored so that it automatically extends its buffers when
877        necessary. The code is crude, but this _is_ just a test program. The
878        default size has been increased from 32K to 50K.
880     2. The code in pcre_study() was using the value of the re argument before
881        testing it for NULL. (Of course, in any sensible call of the function, it
882        won't be NULL.)
884     3. The memmove() emulation function in pcre_internal.h, which is used on
885        systems that lack both memmove() and bcopy() - that is, hardly ever -
886        was missing a "static" storage class specifier.
888     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
889        containing an extended class (one that cannot be represented by a bitmap
890        because it contains high-valued characters or Unicode property items, e.g.
891        [\pZ]). Almost always one would set UTF-8 mode when processing such a
892        pattern, but PCRE should not loop if you do not (it no longer does).
893        [Detail: two cases were found: (a) a repeated subpattern containing an
894        extended class; (b) a recursive reference to a subpattern that followed a
895        previous extended class. It wasn't skipping over the extended class
896        correctly when UTF-8 mode was not set.]
898     5. A negated single-character class was not being recognized as fixed-length
899        in lookbehind assertions such as (?<=[^f]), leading to an incorrect
900        compile error "lookbehind assertion is not fixed length".
902     6. The RunPerlTest auxiliary script was showing an unexpected difference
903        between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
904        write a Perl script that can interpret lines of an input file either as
905        byte characters or as UTF-8, which is what "perltest" was being required to
906        do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
907        can't do is switch easily at run time between having the "use utf8;" pragma
908        or not. In the end, I fudged it by using the RunPerlTest script to insert
909        "use utf8;" explicitly for the UTF-8 tests.
911     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
912        the end of the subject string, contrary to the documentation and to what
913        Perl does. This was true of both matching functions. Now it matches only at
914        the start of the subject and immediately after *internal* newlines.
916     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
917        a pointer to an int instead of a pointer to an unsigned long int. This
918        caused problems on 64-bit systems.
920     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
921        instance of the 'standard' template library not being so standard".
923    10. There was no check on the number of named subpatterns nor the maximum
924        length of a subpattern name. The product of these values is used to compute
925        the size of the memory block for a compiled pattern. By supplying a very
926        long subpattern name and a large number of named subpatterns, the size
927        computation could be caused to overflow. This is now prevented by limiting
928        the length of names to 32 characters, and the number of named subpatterns
929        to 10,000.
931    11. Subpatterns that are repeated with specific counts have to be replicated in
932        the compiled pattern. The size of memory for this was computed from the
933        length of the subpattern and the repeat count. The latter is limited to
934        65535, but there was no limit on the former, meaning that integer overflow
935        could in principle occur. The compiled length of a repeated subpattern is
936        now limited to 30,000 bytes in order to prevent this.
938    12. Added the optional facility to have named substrings with the same name.
940    13. Added the ability to use a named substring as a condition, using the
941        Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
942        are numbers (not recommended). Forward references are permitted.
944    14. Added forward references in named backreferences (if you see what I mean).
946    15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
947        pattern could run off the end of the subject. For example, the pattern
948        "(?s)(.{1,5})"8 did this with the subject "ab".
950    16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
951        PCRE_CASELESS was set when matching characters that were quantified with ?
952        or *.
954    17. A character class other than a single negated character that had a minimum
955        but no maximum quantifier - for example [ab]{6,} - was not handled
956        correctly by pce_dfa_exec(). It would match only one character.
958    18. A valid (though odd) pattern that looked like a POSIX character
959        class but used an invalid character after [ (for example [[,abc,]]) caused
960        pcre_compile() to give the error "Failed: internal error: code overflow" or
961        in some cases to crash with a glibc free() error. This could even happen if
962        the pattern terminated after [[ but there just happened to be a sequence of
963        letters, a binary zero, and a closing ] in the memory that followed.
965    19. Perl's treatment of octal escapes in the range \400 to \777 has changed
966        over the years. Originally (before any Unicode support), just the bottom 8
967        bits were taken. Thus, for example, \500 really meant \100. Nowadays the
968        output from "man perlunicode" includes this:
970          The regular expression compiler produces polymorphic opcodes.  That
971          is, the pattern adapts to the data and automatically switches to
972          the Unicode character scheme when presented with Unicode data--or
973          instead uses a traditional byte scheme when presented with byte
974          data.
976        Sadly, a wide octal escape does not cause a switch, and in a string with
977        no other multibyte characters, these octal escapes are treated as before.
978        Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
979        /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
980        Unicode string.
982        I have not perpetrated such confusion in PCRE. Up till now, it took just
983        the bottom 8 bits, as in old Perl. I have now made octal escapes with
984        values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
985        translate to the appropriate multibyte character.
987    29. Applied some refactoring to reduce the number of warnings from Microsoft
988        and Borland compilers. This has included removing the fudge introduced
989        seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
990        a warning about an unused variable.
992    21. PCRE has not included VT (character 0x0b) in the set of whitespace
993        characters since release 4.0, because Perl (from release 5.004) does not.
994        [Or at least, is documented not to: some releases seem to be in conflict
995        with the documentation.] However, when a pattern was studied with
996        pcre_study() and all its branches started with \s, PCRE still included VT
997        as a possible starting character. Of course, this did no harm; it just
998        caused an unnecessary match attempt.
1000    22. Removed a now-redundant internal flag bit that recorded the fact that case
1001        dependency changed within the pattern. This was once needed for "required
1002        byte" processing, but is no longer used. This recovers a now-scarce options
1003        bit. Also moved the least significant internal flag bit to the most-
1004        significant bit of the word, which was not previously used (hangover from
1005        the days when it was an int rather than a uint) to free up another bit for
1006        the future.
1008    23. Added support for CRLF line endings as well as CR and LF. As well as the
1009        default being selectable at build time, it can now be changed at runtime
1010        via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
1011        specify that it is scanning data with non-default line endings.
1013    24. Changed the definition of CXXLINK to make it agree with the definition of
1014        LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
1016    25. Applied Ian Taylor's patches to avoid using another stack frame for tail
1017        recursions. This makes a big different to stack usage for some patterns.
1019    26. If a subpattern containing a named recursion or subroutine reference such
1020        as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
1021        the space required for the compiled pattern went wrong and gave too small a
1022        value. Depending on the environment, this could lead to "Failed: internal
1023        error: code overflow at offset 49" or "glibc detected double free or
1024        corruption" errors.
1026    27. Applied patches from Google (a) to support the new newline modes and (b) to
1027        advance over multibyte UTF-8 characters in GlobalReplace.
1029    28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
1030        difference for some implementation of PCRE in some Windows version.
1032    29. Added some extra testing facilities to pcretest:
1034        \q<number>   in a data line sets the "match limit" value
1035        \Q<number>   in a data line sets the "match recursion limt" value
1036        -S <number>  sets the stack size, where <number> is in megabytes
1038        The -S option isn't available for Windows.
1041    Version 6.6 06-Feb-06
1042    ---------------------
1044     1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
1045        in pcreposix.h. I have copied the definition from pcre.h.
1047     2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
1048        because pcre.h is no longer a built file.
1050     3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
1051        not normally included in the compiled code.
1054    Version 6.5 01-Feb-06
1055    ---------------------
1057     1. When using the partial match feature with pcre_dfa_exec(), it was not
1058        anchoring the second and subsequent partial matches at the new starting
1059        point. This could lead to incorrect results. For example, with the pattern
1060        /1234/, partially matching against "123" and then "a4" gave a match.
1062     2. Changes to pcregrep:
1064        (a) All non-match returns from pcre_exec() were being treated as failures
1065            to match the line. Now, unless the error is PCRE_ERROR_NOMATCH, an
1066            error message is output. Some extra information is given for the
1067            PCRE_ERROR_MATCHLIMIT and PCRE_ERROR_RECURSIONLIMIT errors, which are
1068            probably the only errors that are likely to be caused by users (by
1069            specifying a regex that has nested indefinite repeats, for instance).
1070            If there are more than 20 of these errors, pcregrep is abandoned.
1072        (b) A binary zero was treated as data while matching, but terminated the
1073            output line if it was written out. This has been fixed: binary zeroes
1074            are now no different to any other data bytes.
1076        (c) Whichever of the LC_ALL or LC_CTYPE environment variables is set is
1077            used to set a locale for matching. The --locale=xxxx long option has
1078            been added (no short equivalent) to specify a locale explicitly on the
1079            pcregrep command, overriding the environment variables.
1081        (d) When -B was used with -n, some line numbers in the output were one less
1082            than they should have been.
1084        (e) Added the -o (--only-matching) option.
1086        (f) If -A or -C was used with -c (count only), some lines of context were
1087            accidentally printed for the final match.
1089        (g) Added the -H (--with-filename) option.
1091        (h) The combination of options -rh failed to suppress file names for files
1092            that were found from directory arguments.
1094        (i) Added the -D (--devices) and -d (--directories) options.
1096        (j) Added the -F (--fixed-strings) option.
1098        (k) Allow "-" to be used as a file name for -f as well as for a data file.
1100        (l) Added the --colo(u)r option.
1102        (m) Added Jeffrey Friedl's -S testing option, but within #ifdefs so that it
1103            is not present by default.
1105     3. A nasty bug was discovered in the handling of recursive patterns, that is,
1106        items such as (?R) or (?1), when the recursion could match a number of
1107        alternatives. If it matched one of the alternatives, but subsequently,
1108        outside the recursion, there was a failure, the code tried to back up into
1109        the recursion. However, because of the way PCRE is implemented, this is not
1110        possible, and the result was an incorrect result from the match.
1112        In order to prevent this happening, the specification of recursion has
1113        been changed so that all such subpatterns are automatically treated as
1114        atomic groups. Thus, for example, (?R) is treated as if it were (?>(?R)).
1116     4. I had overlooked the fact that, in some locales, there are characters for
1117        which isalpha() is true but neither isupper() nor islower() are true. In
1118        the fr_FR locale, for instance, the \xAA and \xBA characters (ordmasculine
1119        and ordfeminine) are like this. This affected the treatment of \w and \W
1120        when they appeared in character classes, but not when they appeared outside
1121        a character class. The bit map for "word" characters is now created
1122        separately from the results of isalnum() instead of just taking it from the
1123        upper, lower, and digit maps. (Plus the underscore character, of course.)
1125     5. The above bug also affected the handling of POSIX character classes such as
1126        [[:alpha:]] and [[:alnum:]]. These do not have their own bit maps in PCRE's
1127        permanent tables. Instead, the bit maps for such a class were previously
1128        created as the appropriate unions of the upper, lower, and digit bitmaps.
1129        Now they are created by subtraction from the [[:word:]] class, which has
1130        its own bitmap.
1132     6. The [[:blank:]] character class matches horizontal, but not vertical space.
1133        It is created by subtracting the vertical space characters (\x09, \x0a,
1134        \x0b, \x0c) from the [[:space:]] bitmap. Previously, however, the
1135        subtraction was done in the overall bitmap for a character class, meaning
1136        that a class such as [\x0c[:blank:]] was incorrect because \x0c would not
1137        be recognized. This bug has been fixed.
1139     7. Patches from the folks at Google:
1141          (a) pcrecpp.cc: "to handle a corner case that may or may not happen in
1142          real life, but is still worth protecting against".
1144          (b) pcrecpp.cc: "corrects a bug when negative radixes are used with
1145          regular expressions".
1147          (c) pcre_scanner.cc: avoid use of std::count() because not all systems
1148          have it.
1150          (d) Split off pcrecpparg.h from pcrecpp.h and had the former built by
1151          "configure" and the latter not, in order to fix a problem somebody had
1152          with compiling the Arg class on HP-UX.
1154          (e) Improve the error-handling of the C++ wrapper a little bit.
1156          (f) New tests for checking recursion limiting.
1158     8. The pcre_memmove() function, which is used only if the environment does not
1159        have a standard memmove() function (and is therefore rarely compiled),
1160        contained two bugs: (a) use of int instead of size_t, and (b) it was not
1161        returning a result (though PCRE never actually uses the result).
1163     9. In the POSIX regexec() interface, if nmatch is specified as a ridiculously
1164        large number - greater than INT_MAX/(3*sizeof(int)) - REG_ESPACE is
1165        returned instead of calling malloc() with an overflowing number that would
1166        most likely cause subsequent chaos.
1168    10. The debugging option of pcretest was not showing the NO_AUTO_CAPTURE flag.
1170    11. The POSIX flag REG_NOSUB is now supported. When a pattern that was compiled
1171        with this option is matched, the nmatch and pmatch options of regexec() are
1172        ignored.
1174    12. Added REG_UTF8 to the POSIX interface. This is not defined by POSIX, but is
1175        provided in case anyone wants to the the POSIX interface with UTF-8
1176        strings.
1178    13. Added CXXLDFLAGS to the Makefile parameters to provide settings only on the
1179        C++ linking (needed for some HP-UX environments).
1181    14. Avoid compiler warnings in get_ucpname() when compiled without UCP support
1182        (unused parameter) and in the pcre_printint() function (omitted "default"
1183        switch label when the default is to do nothing).
1185    15. Added some code to make it possible, when PCRE is compiled as a C++
1186        library, to replace subject pointers for pcre_exec() with a smart pointer
1187        class, thus making it possible to process discontinuous strings.
1189    16. The two macros PCRE_EXPORT and PCRE_DATA_SCOPE are confusing, and perform
1190        much the same function. They were added by different people who were trying
1191        to make PCRE easy to compile on non-Unix systems. It has been suggested
1192        that PCRE_EXPORT be abolished now that there is more automatic apparatus
1193        for compiling on Windows systems. I have therefore replaced it with
1194        PCRE_DATA_SCOPE. This is set automatically for Windows; if not set it
1195        defaults to "extern" for C or "extern C" for C++, which works fine on
1196        Unix-like systems. It is now possible to override the value of PCRE_DATA_
1197        SCOPE with something explicit in config.h. In addition:
1199        (a) pcreposix.h still had just "extern" instead of either of these macros;
1200            I have replaced it with PCRE_DATA_SCOPE.
1202        (b) Functions such as _pcre_xclass(), which are internal to the library,
1203            but external in the C sense, all had PCRE_EXPORT in their definitions.
1204            This is apparently wrong for the Windows case, so I have removed it.
1205            (It makes no difference on Unix-like systems.)
1207    17. Added a new limit, MATCH_LIMIT_RECURSION, which limits the depth of nesting
1208        of recursive calls to match(). This is different to MATCH_LIMIT because
1209        that limits the total number of calls to match(), not all of which increase
1210        the depth of recursion. Limiting the recursion depth limits the amount of
1211        stack (or heap if NO_RECURSE is set) that is used. The default can be set
1212        when PCRE is compiled, and changed at run time. A patch from Google adds
1213        this functionality to the C++ interface.
1215    18. Changes to the handling of Unicode character properties:
1217        (a) Updated the table to Unicode 4.1.0.
1219        (b) Recognize characters that are not in the table as "Cn" (undefined).
1221        (c) I revised the way the table is implemented to a much improved format
1222            which includes recognition of ranges. It now supports the ranges that
1223            are defined in UnicodeData.txt, and it also amalgamates other
1224            characters into ranges. This has reduced the number of entries in the
1225            table from around 16,000 to around 3,000, thus reducing its size
1226            considerably. I realized I did not need to use a tree structure after
1227            all - a binary chop search is just as efficient. Having reduced the
1228            number of entries, I extended their size from 6 bytes to 8 bytes to
1229            allow for more data.
1231        (d) Added support for Unicode script names via properties such as \p{Han}.
1233    19. In UTF-8 mode, a backslash followed by a non-Ascii character was not
1234        matching that character.
1236    20. When matching a repeated Unicode property with a minimum greater than zero,
1237        (for example \pL{2,}), PCRE could look past the end of the subject if it
1238        reached it while seeking the minimum number of characters. This could
1239        happen only if some of the characters were more than one byte long, because
1240        there is a check for at least the minimum number of bytes.
1242    21. Refactored the implementation of \p and \P so as to be more general, to
1243        allow for more different types of property in future. This has changed the
1244        compiled form incompatibly. Anybody with saved compiled patterns that use
1245        \p or \P will have to recompile them.
1247    22. Added "Any" and "L&" to the supported property types.
1249    23. Recognize \x{...} as a code point specifier, even when not in UTF-8 mode,
1250        but give a compile time error if the value is greater than 0xff.
1252    24. The man pages for pcrepartial, pcreprecompile, and pcre_compile2 were
1253        accidentally not being installed or uninstalled.
1255    25. The pcre.h file was built from pcre.h.in, but the only changes that were
1256        made were to insert the current release number. This seemed silly, because
1257        it made things harder for people building PCRE on systems that don't run
1258        "configure". I have turned pcre.h into a distributed file, no longer built
1259        by "configure", with the version identification directly included. There is
1260        no longer a pcre.h.in file.
1262        However, this change necessitated a change to the pcre-config script as
1263        well. It is built from pcre-config.in, and one of the substitutions was the
1264        release number. I have updated configure.ac so that ./configure now finds
1265        the release number by grepping pcre.h.
1267    26. Added the ability to run the tests under valgrind.
1270    Version 6.4 05-Sep-05
1271    ---------------------
1273     1. Change 6.0/10/(l) to pcregrep introduced a bug that caused separator lines
1274        "--" to be printed when multiple files were scanned, even when none of the
1275        -A, -B, or -C options were used. This is not compatible with Gnu grep, so I
1276        consider it to be a bug, and have restored the previous behaviour.
1278     2. A couple of code tidies to get rid of compiler warnings.
1280     3. The pcretest program used to cheat by referring to symbols in the library
1281        whose names begin with _pcre_. These are internal symbols that are not
1282        really supposed to be visible externally, and in some environments it is
1283        possible to suppress them. The cheating is now confined to including
1284        certain files from the library's source, which is a bit cleaner.
1286     4. Renamed pcre.in as pcre.h.in to go with pcrecpp.h.in; it also makes the
1287        file's purpose clearer.
1289     5. Reorganized pcre_ucp_findchar().
1292    Version 6.3 15-Aug-05
1293    ---------------------
1295     1. The file libpcre.pc.in did not have general read permission in the tarball.
1297     2. There were some problems when building without C++ support:
1299        (a) If C++ support was not built, "make install" and "make test" still
1300            tried to test it.
1302        (b) There were problems when the value of CXX was explicitly set. Some
1303            changes have been made to try to fix these, and ...
1305        (c) --disable-cpp can now be used to explicitly disable C++ support.
1307        (d) The use of @CPP_OBJ@ directly caused a blank line preceded by a
1308            backslash in a target when C++ was disabled. This confuses some
1309            versions of "make", apparently. Using an intermediate variable solves
1310            this. (Same for CPP_LOBJ.)
1312     3. $(LINK_FOR_BUILD) now includes $(CFLAGS_FOR_BUILD) and $(LINK)
1313        (non-Windows) now includes $(CFLAGS) because these flags are sometimes
1314        necessary on certain architectures.
1316     4. Added a setting of -export-symbols-regex to the link command to remove
1317        those symbols that are exported in the C sense, but actually are local
1318        within the library, and not documented. Their names all begin with
1319        "_pcre_". This is not a perfect job, because (a) we have to except some
1320        symbols that pcretest ("illegally") uses, and (b) the facility isn't always
1321        available (and never for static libraries). I have made a note to try to
1322        find a way round (a) in the future.
1325    Version 6.2 01-Aug-05
1326    ---------------------
1328     1. There was no test for integer overflow of quantifier values. A construction
1329        such as {1111111111111111} would give undefined results. What is worse, if
1330        a minimum quantifier for a parenthesized subpattern overflowed and became
1331        negative, the calculation of the memory size went wrong. This could have
1332        led to memory overwriting.
1334     2. Building PCRE using VPATH was broken. Hopefully it is now fixed.
1336     3. Added "b" to the 2nd argument of fopen() in dftables.c, for non-Unix-like
1337        operating environments where this matters.
1339     4. Applied Giuseppe Maxia's patch to add additional features for controlling
1340        PCRE options from within the C++ wrapper.
1342     5. Named capturing subpatterns were not being correctly counted when a pattern
1343        was compiled. This caused two problems: (a) If there were more than 100
1344        such subpatterns, the calculation of the memory needed for the whole
1345        compiled pattern went wrong, leading to an overflow error. (b) Numerical
1346        back references of the form \12, where the number was greater than 9, were
1347        not recognized as back references, even though there were sufficient
1348        previous subpatterns.
1350     6. Two minor patches to pcrecpp.cc in order to allow it to compile on older
1351        versions of gcc, e.g. 2.95.4.
1354    Version 6.1 21-Jun-05
1355    ---------------------
1357     1. There was one reference to the variable "posix" in pcretest.c that was not
1358        surrounded by "#if !defined NOPOSIX".
1360     2. Make it possible to compile pcretest without DFA support, UTF8 support, or
1361        the cross-check on the old pcre_info() function, for the benefit of the
1362        cut-down version of PCRE that is currently imported into Exim.
1364     3. A (silly) pattern starting with (?i)(?-i) caused an internal space
1365        allocation error. I've done the easy fix, which wastes 2 bytes for sensible
1366        patterns that start (?i) but I don't think that matters. The use of (?i) is
1367        just an example; this all applies to the other options as well.
1369     4. Since libtool seems to echo the compile commands it is issuing, the output
1370        from "make" can be reduced a bit by putting "@" in front of each libtool
1371        compile command.
1373     5. Patch from the folks at Google for configure.in to be a bit more thorough
1374        in checking for a suitable C++ installation before trying to compile the
1375        C++ stuff. This should fix a reported problem when a compiler was present,
1376        but no suitable headers.
1378     6. The man pages all had just "PCRE" as their title. I have changed them to
1379        be the relevant file name. I have also arranged that these names are
1380        retained in the file doc/pcre.txt, which is a concatenation in text format
1381        of all the man pages except the little individual ones for each function.
1383     7. The NON-UNIX-USE file had not been updated for the different set of source
1384        files that come with release 6. I also added a few comments about the C++
1385        wrapper.
1388    Version 6.0 07-Jun-05
1389    ---------------------
1391     1. Some minor internal re-organization to help with my DFA experiments.
1393     2. Some missing #ifdef SUPPORT_UCP conditionals in pcretest and printint that
1394        didn't matter for the library itself when fully configured, but did matter
1395        when compiling without UCP support, or within Exim, where the ucp files are
1396        not imported.
1398     3. Refactoring of the library code to split up the various functions into
1399        different source modules. The addition of the new DFA matching code (see
1400        below) to a single monolithic source would have made it really too
1401        unwieldy, quite apart from causing all the code to be include in a
1402        statically linked application, when only some functions are used. This is
1403        relevant even without the DFA addition now that patterns can be compiled in
1404        one application and matched in another.
1406        The downside of splitting up is that there have to be some external
1407        functions and data tables that are used internally in different modules of
1408        the library but which are not part of the API. These have all had their
1409        names changed to start with "_pcre_" so that they are unlikely to clash
1410        with other external names.
1412     4. Added an alternate matching function, pcre_dfa_exec(), which matches using
1413        a different (DFA) algorithm. Although it is slower than the original
1414        function, it does have some advantages for certain types of matching
1415        problem.
1417     5. Upgrades to pcretest in order to test the features of pcre_dfa_exec(),
1418        including restarting after a partial match.
1420     6. A patch for pcregrep that defines INVALID_FILE_ATTRIBUTES if it is not
1421        defined when compiling for Windows was sent to me. I have put it into the
1422        code, though I have no means of testing or verifying it.
1424     7. Added the pcre_refcount() auxiliary function.
1426     8. Added the PCRE_FIRSTLINE option. This constrains an unanchored pattern to
1427        match before or at the first newline in the subject string. In pcretest,
1428        the /f option on a pattern can be used to set this.
1430     9. A repeated \w when used in UTF-8 mode with characters greater than 256
1431        would behave wrongly. This has been present in PCRE since release 4.0.
1433    10. A number of changes to the pcregrep command:
1435        (a) Refactored how -x works; insert ^(...)$ instead of setting
1436            PCRE_ANCHORED and checking the length, in preparation for adding
1437            something similar for -w.
1439        (b) Added the -w (match as a word) option.
1441        (c) Refactored the way lines are read and buffered so as to have more
1442            than one at a time available.
1444        (d) Implemented a pcregrep test script.
1446        (e) Added the -M (multiline match) option. This allows patterns to match
1447            over several lines of the subject. The buffering ensures that at least
1448            8K, or the rest of the document (whichever is the shorter) is available
1449            for matching (and similarly the previous 8K for lookbehind assertions).
1451        (f) Changed the --help output so that it now says
1453              -w, --word-regex(p)
1455            instead of two lines, one with "regex" and the other with "regexp"
1456            because that confused at least one person since the short forms are the
1457            same. (This required a bit of code, as the output is generated
1458            automatically from a table. It wasn't just a text change.)
1460        (g) -- can be used to terminate pcregrep options if the next thing isn't an
1461            option but starts with a hyphen. Could be a pattern or a path name
1462            starting with a hyphen, for instance.
1464        (h) "-" can be given as a file name to represent stdin.
1466        (i) When file names are being printed, "(standard input)" is used for
1467            the standard input, for compatibility with GNU grep. Previously
1468            "<stdin>" was used.
1470        (j) The option --label=xxx can be used to supply a name to be used for
1471            stdin when file names are being printed. There is no short form.
1473        (k) Re-factored the options decoding logic because we are going to add
1474            two more options that take data. Such options can now be given in four
1475            different ways, e.g. "-fname", "-f name", "--file=name", "--file name".
1477        (l) Added the -A, -B, and -C options for requesting that lines of context
1478            around matches be printed.
1480        (m) Added the -L option to print the names of files that do not contain
1481            any matching lines, that is, the complement of -l.
1483        (n) The return code is 2 if any file cannot be opened, but pcregrep does
1484            continue to scan other files.
1486        (o) The -s option was incorrectly implemented. For compatibility with other
1487            greps, it now suppresses the error message for a non-existent or non-
1488            accessible file (but not the return code). There is a new option called
1489            -q that suppresses the output of matching lines, which was what -s was
1490            previously doing.
1492        (p) Added --include and --exclude options to specify files for inclusion
1493            and exclusion when recursing.
1495    11. The Makefile was not using the Autoconf-supported LDFLAGS macro properly.
1496        Hopefully, it now does.
1498    12. Missing cast in pcre_study().
1500    13. Added an "uninstall" target to the makefile.
1502    14. Replaced "extern" in the function prototypes in Makefile.in with
1503        "PCRE_DATA_SCOPE", which defaults to 'extern' or 'extern "C"' in the Unix
1504        world, but is set differently for Windows.
1506    15. Added a second compiling function called pcre_compile2(). The only
1507        difference is that it has an extra argument, which is a pointer to an
1508        integer error code. When there is a compile-time failure, this is set
1509        non-zero, in addition to the error test pointer being set to point to an
1510        error message. The new argument may be NULL if no error number is required
1511        (but then you may as well call pcre_compile(), which is now just a
1512        wrapper). This facility is provided because some applications need a
1513        numeric error indication, but it has also enabled me to tidy up the way
1514        compile-time errors are handled in the POSIX wrapper.
1516    16. Added VPATH=.libs to the makefile; this should help when building with one
1517        prefix path and installing with another. (Or so I'm told by someone who
1518        knows more about this stuff than I do.)
1520    17. Added a new option, REG_DOTALL, to the POSIX function regcomp(). This
1521        passes PCRE_DOTALL to the pcre_compile() function, making the "." character
1522        match everything, including newlines. This is not POSIX-compatible, but
1523        somebody wanted the feature. From pcretest it can be activated by using
1524        both the P and the s flags.
1526    18. AC_PROG_LIBTOOL appeared twice in Makefile.in. Removed one.
1528    19. libpcre.pc was being incorrectly installed as executable.
1530    20. A couple of places in pcretest check for end-of-line by looking for '\n';
1531        it now also looks for '\r' so that it will work unmodified on Windows.
1533    21. Added Google's contributed C++ wrapper to the distribution.
1535    22. Added some untidy missing memory free() calls in pcretest, to keep
1536        Electric Fence happy when testing.
1540    Version 5.0 13-Sep-04
1541    ---------------------
1543     1. Internal change: literal characters are no longer packed up into items
1544        containing multiple characters in a single byte-string. Each character
1545        is now matched using a separate opcode. However, there may be more than one
1546        byte in the character in UTF-8 mode.
1548     2. The pcre_callout_block structure has two new fields: pattern_position and
1549        next_item_length. These contain the offset in the pattern to the next match
1550        item, and its length, respectively.
1552     3. The PCRE_AUTO_CALLOUT option for pcre_compile() requests the automatic
1553        insertion of callouts before each pattern item. Added the /C option to
1554        pcretest to make use of this.
1556     4. On the advice of a Windows user, the lines
1558          #if defined(_WIN32) || defined(WIN32)
1559          _setmode( _fileno( stdout ), 0x8000 );
1560          #endif  /* defined(_WIN32) || defined(WIN32) */
1562        have been added to the source of pcretest. This apparently does useful
1563        magic in relation to line terminators.
1565     5. Changed "r" and "w" in the calls to fopen() in pcretest to "rb" and "wb"
1566        for the benefit of those environments where the "b" makes a difference.
1568     6. The icc compiler has the same options as gcc, but "configure" doesn't seem
1569        to know about it. I have put a hack into configure.in that adds in code
1570        to set GCC=yes if CC=icc. This seems to end up at a point in the
1571        generated configure script that is early enough to affect the setting of
1572        compiler options, which is what is needed, but I have no means of testing
1573        whether it really works. (The user who reported this had patched the
1574        generated configure script, which of course I cannot do.)
1576        LATER: After change 22 below (new libtool files), the configure script
1577        seems to know about icc (and also ecc). Therefore, I have commented out
1578        this hack in configure.in.
1580     7. Added support for pkg-config (2 patches were sent in).
1582     8. Negated POSIX character classes that used a combination of internal tables
1583        were completely broken. These were [[:^alpha:]], [[:^alnum:]], and
1584        [[:^ascii]]. Typically, they would match almost any characters. The other
1585        POSIX classes were not broken in this way.
1587     9. Matching the pattern "\b.*?" against "ab cd", starting at offset 1, failed
1588        to find the match, as PCRE was deluded into thinking that the match had to
1589        start at the start point or following a newline. The same bug applied to
1590        patterns with negative forward assertions or any backward assertions
1591        preceding ".*" at the start, unless the pattern required a fixed first
1592        character. This was a failing pattern: "(?!.bcd).*". The bug is now fixed.
1594    10. In UTF-8 mode, when moving forwards in the subject after a failed match
1595        starting at the last subject character, bytes beyond the end of the subject
1596        string were read.
1598    11. Renamed the variable "class" as "classbits" to make life easier for C++
1599        users. (Previously there was a macro definition, but it apparently wasn't
1600        enough.)
1602    12. Added the new field "tables" to the extra data so that tables can be passed
1603        in at exec time, or the internal tables can be re-selected. This allows
1604        a compiled regex to be saved and re-used at a later time by a different
1605        program that might have everything at different addresses.
1607    13. Modified the pcre-config script so that, when run on Solaris, it shows a
1608        -R library as well as a -L library.
1610    14. The debugging options of pcretest (-d on the command line or D on a
1611        pattern) showed incorrect output for anything following an extended class
1612        that contained multibyte characters and which was followed by a quantifier.
1614    15. Added optional support for general category Unicode character properties
1615        via the \p, \P, and \X escapes. Unicode property support implies UTF-8
1616        support. It adds about 90K to the size of the library. The meanings of the
1617        inbuilt class escapes such as \d and \s have NOT been changed.
1619    16. Updated pcredemo.c to include calls to free() to release the memory for the
1620        compiled pattern.
1622    17. The generated file chartables.c was being created in the source directory
1623        instead of in the building directory. This caused the build to fail if the
1624        source directory was different from the building directory, and was
1625        read-only.
1627    18. Added some sample Win commands from Mark Tetrode into the NON-UNIX-USE
1628        file. No doubt somebody will tell me if they don't make sense... Also added
1629        Dan Mooney's comments about building on OpenVMS.
1631    19. Added support for partial matching via the PCRE_PARTIAL option for
1632        pcre_exec() and the \P data escape in pcretest.
1634    20. Extended pcretest with 3 new pattern features:
1636        (i)   A pattern option of the form ">rest-of-line" causes pcretest to
1637              write the compiled pattern to the file whose name is "rest-of-line".
1638              This is a straight binary dump of the data, with the saved pointer to
1639              the character tables forced to be NULL. The study data, if any, is
1640              written too. After writing, pcretest reads a new pattern.
1642        (ii)  If, instead of a pattern, "<rest-of-line" is given, pcretest reads a
1643              compiled pattern from the given file. There must not be any
1644              occurrences of "<" in the file name (pretty unlikely); if there are,
1645              pcretest will instead treat the initial "<" as a pattern delimiter.
1646              After reading in the pattern, pcretest goes on to read data lines as
1647              usual.
1649        (iii) The F pattern option causes pcretest to flip the bytes in the 32-bit
1650              and 16-bit fields in a compiled pattern, to simulate a pattern that
1651              was compiled on a host of opposite endianness.
1653    21. The pcre-exec() function can now cope with patterns that were compiled on
1654        hosts of opposite endianness, with this restriction:
1656          As for any compiled expression that is saved and used later, the tables
1657          pointer field cannot be preserved; the extra_data field in the arguments
1658          to pcre_exec() should be used to pass in a tables address if a value
1659          other than the default internal tables were used at compile time.
1661    22. Calling pcre_exec() with a negative value of the "ovecsize" parameter is
1662        now diagnosed as an error. Previously, most of the time, a negative number
1663        would have been treated as zero, but if in addition "ovector" was passed as
1664        NULL, a crash could occur.
1666    23. Updated the files ltmain.sh, config.sub, config.guess, and aclocal.m4 with
1667        new versions from the libtool 1.5 distribution (the last one is a copy of
1668        a file called libtool.m4). This seems to have fixed the need to patch
1669        "configure" to support Darwin 1.3 (which I used to do). However, I still
1670        had to patch ltmain.sh to ensure that ${SED} is set (it isn't on my
1671        workstation).
1673    24. Changed the PCRE licence to be the more standard "BSD" licence.
1676    Version 4.5 01-Dec-03
1677    ---------------------
1679     1. There has been some re-arrangement of the code for the match() function so
1680        that it can be compiled in a version that does not call itself recursively.
1681        Instead, it keeps those local variables that need separate instances for
1682        each "recursion" in a frame on the heap, and gets/frees frames whenever it
1683        needs to "recurse". Keeping track of where control must go is done by means
1684        of setjmp/longjmp. The whole thing is implemented by a set of macros that
1685        hide most of the details from the main code, and operates only if
1686        NO_RECURSE is defined while compiling pcre.c. If PCRE is built using the
1687        "configure" mechanism, "--disable-stack-for-recursion" turns on this way of
1688        operating.
1690        To make it easier for callers to provide specially tailored get/free
1691        functions for this usage, two new functions, pcre_stack_malloc, and
1692        pcre_stack_free, are used. They are always called in strict stacking order,
1693        and the size of block requested is always the same.
1695        The PCRE_CONFIG_STACKRECURSE info parameter can be used to find out whether
1696        PCRE has been compiled to use the stack or the heap for recursion. The
1697        -C option of pcretest uses this to show which version is compiled.
1699        A new data escape \S, is added to pcretest; it causes the amounts of store
1700        obtained and freed by both kinds of malloc/free at match time to be added
1701        to the output.
1703     2. Changed the locale test to use "fr_FR" instead of "fr" because that's
1704        what's available on my current Linux desktop machine.
1706     3. When matching a UTF-8 string, the test for a valid string at the start has
1707        been extended. If start_offset is not zero, PCRE now checks that it points
1708        to a byte that is the start of a UTF-8 character. If not, it returns
1709        PCRE_ERROR_BADUTF8_OFFSET (-11). Note: the whole string is still checked;
1710        this is necessary because there may be backward assertions in the pattern.
1711        When matching the same subject several times, it may save resources to use
1712        PCRE_NO_UTF8_CHECK on all but the first call if the string is long.
1714     4. The code for checking the validity of UTF-8 strings has been tightened so
1715        that it rejects (a) strings containing 0xfe or 0xff bytes and (b) strings
1716        containing "overlong sequences".
1718     5. Fixed a bug (appearing twice) that I could not find any way of exploiting!
1719        I had written "if ((digitab[*p++] && chtab_digit) == 0)" where the "&&"
1720        should have been "&", but it just so happened that all the cases this let
1721        through by mistake were picked up later in the function.
1723     6. I had used a variable called "isblank" - this is a C99 function, causing
1724        some compilers to warn. To avoid this, I renamed it (as "blankclass").
1726     7. Cosmetic: (a) only output another newline at the end of pcretest if it is
1727        prompting; (b) run "./pcretest /dev/null" at the start of the test script
1728        so the version is shown; (c) stop "make test" echoing "./RunTest".
1730     8. Added patches from David Burgess to enable PCRE to run on EBCDIC systems.
1732     9. The prototype for memmove() for systems that don't have it was using
1733        size_t, but the inclusion of the header that defines size_t was later. I've
1734        moved the #includes for the C headers earlier to avoid this.
1736    10. Added some adjustments to the code to make it easier to compiler on certain
1737        special systems:
1739          (a) Some "const" qualifiers were missing.
1740          (b) Added the macro EXPORT before all exported functions; by default this
1741              is defined to be empty.
1742          (c) Changed the dftables auxiliary program (that builds chartables.c) so
1743              that it reads its output file name as an argument instead of writing
1744              to the standard output and assuming this can be redirected.
1746    11. In UTF-8 mode, if a recursive reference (e.g. (?1)) followed a character
1747        class containing characters with values greater than 255, PCRE compilation
1748        went into a loop.
1750    12. A recursive reference to a subpattern that was within another subpattern
1751        that had a minimum quantifier of zero caused PCRE to crash. For example,
1752        (x(y(?2))z)? provoked this bug with a subject that got as far as the
1753        recursion. If the recursively-called subpattern itself had a zero repeat,
1754        that was OK.
1756    13. In pcretest, the buffer for reading a data line was set at 30K, but the
1757        buffer into which it was copied (for escape processing) was still set at
1758        1024, so long lines caused crashes.
1760    14. A pattern such as /[ab]{1,3}+/ failed to compile, giving the error
1761        "internal error: code overflow...". This applied to any character class
1762        that was followed by a possessive quantifier.
1764    15. Modified the Makefile to add libpcre.la as a prerequisite for
1765        libpcreposix.la because I was told this is needed for a parallel build to
1766        work.
1768    16. If a pattern that contained .* following optional items at the start was
1769        studied, the wrong optimizing data was generated, leading to matching
1770        errors. For example, studying /[ab]*.*c/ concluded, erroneously, that any
1771        matching string must start with a or b or c. The correct conclusion for
1772        this pattern is that a match can start with any character.
1775    Version 4.4 13-Aug-03
1776    ---------------------
1778     1. In UTF-8 mode, a character class containing characters with values between
1779        127 and 255 was not handled correctly if the compiled pattern was studied.
1780        In fixing this, I have also improved the studying algorithm for such
1781        classes (slightly).
1783     2. Three internal functions had redundant arguments passed to them. Removal
1784        might give a very teeny performance improvement.
1786     3. Documentation bug: the value of the capture_top field in a callout is *one
1787        more than* the number of the hightest numbered captured substring.
1789     4. The Makefile linked pcretest and pcregrep with -lpcre, which could result
1790        in incorrectly linking with a previously installed version. They now link
1791        explicitly with libpcre.la.
1793     5. configure.in no longer needs to recognize Cygwin specially.
1795     6. A problem in pcre.in for Windows platforms is fixed.
1797     7. If a pattern was successfully studied, and the -d (or /D) flag was given to
1798        pcretest, it used to include the size of the study block as part of its
1799        output. Unfortunately, the structure contains a field that has a different
1800        size on different hardware architectures. This meant that the tests that
1801        showed this size failed. As the block is currently always of a fixed size,
1802        this information isn't actually particularly useful in pcretest output, so
1803        I have just removed it.
1805     8. Three pre-processor statements accidentally did not start in column 1.
1806        Sadly, there are *still* compilers around that complain, even though
1807        standard C has not required this for well over a decade. Sigh.
1809     9. In pcretest, the code for checking callouts passed small integers in the
1810        callout_data field, which is a void * field. However, some picky compilers
1811        complained about the casts involved for this on 64-bit systems. Now
1812        pcretest passes the address of the small integer instead, which should get
1813        rid of the warnings.
1815    10. By default, when in UTF-8 mode, PCRE now checks for valid UTF-8 strings at
1816        both compile and run time, and gives an error if an invalid UTF-8 sequence
1817        is found. There is a option for disabling this check in cases where the
1818        string is known to be correct and/or the maximum performance is wanted.
1820    11. In response to a bug report, I changed one line in Makefile.in from
1822            -Wl,--out-implib,.libs/lib@WIN_PREFIX@pcreposix.dll.a \
1823        to
1824            -Wl,--out-implib,.libs/@WIN_PREFIX@libpcreposix.dll.a \
1826        to look similar to other lines, but I have no way of telling whether this
1827        is the right thing to do, as I do not use Windows. No doubt I'll get told
1828        if it's wrong...
1831    Version 4.3 21-May-03
1832    ---------------------
1834    1. Two instances of @WIN_PREFIX@ omitted from the Windows targets in the
1835       Makefile.
1837    2. Some refactoring to improve the quality of the code:
1839       (i)   The utf8_table... variables are now declared "const".
1841       (ii)  The code for \cx, which used the "case flipping" table to upper case
1842             lower case letters, now just substracts 32. This is ASCII-specific,
1843             but the whole concept of \cx is ASCII-specific, so it seems
1844             reasonable.
1846       (iii) PCRE was using its character types table to recognize decimal and
1847             hexadecimal digits in the pattern. This is silly, because it handles
1848             only 0-9, a-f, and A-F, but the character types table is locale-
1849             specific, which means strange things might happen. A private
1850             table is now used for this - though it costs 256 bytes, a table is
1851             much faster than multiple explicit tests. Of course, the standard
1852             character types table is still used for matching digits in subject
1853             strings against \d.
1855       (iv)  Strictly, the identifier ESC_t is reserved by POSIX (all identifiers
1856             ending in _t are). So I've renamed it as ESC_tee.
1858    3. The first argument for regexec() in the POSIX wrapper should have been
1859       defined as "const".
1861    4. Changed pcretest to use malloc() for its buffers so that they can be
1862       Electric Fenced for debugging.
1864    5. There were several places in the code where, in UTF-8 mode, PCRE would try
1865       to read one or more bytes before the start of the subject string. Often this
1866       had no effect on PCRE's behaviour, but in some circumstances it could
1867       provoke a segmentation fault.
1869    6. A lookbehind at the start of a pattern in UTF-8 mode could also cause PCRE
1870       to try to read one or more bytes before the start of the subject string.
1872    7. A lookbehind in a pattern matched in non-UTF-8 mode on a PCRE compiled with
1873       UTF-8 support could misbehave in various ways if the subject string
1874       contained bytes with the 0x80 bit set and the 0x40 bit unset in a lookbehind
1875       area. (PCRE was not checking for the UTF-8 mode flag, and trying to move
1876       back over UTF-8 characters.)
1879    Version 4.2 14-Apr-03
1880    ---------------------
1882    1. Typo "#if SUPPORT_UTF8" instead of "#ifdef SUPPORT_UTF8" fixed.
1884    2. Changes to the building process, supplied by Ronald Landheer-Cieslak
1885         [ON_WINDOWS]: new variable, "#" on non-Windows platforms
1886         [NOT_ON_WINDOWS]: new variable, "#" on Windows platforms
1887         [WIN_PREFIX]: new variable, "cyg" for Cygwin
1888         * Makefile.in: use autoconf substitution for OBJEXT, EXEEXT, BUILD_OBJEXT
1889           and BUILD_EXEEXT
1890         Note: automatic setting of the BUILD variables is not yet working
1891         set CPPFLAGS and BUILD_CPPFLAGS (but don't use yet) - should be used at
1892           compile-time but not at link-time
1893         [LINK]: use for linking executables only
1894         make different versions for Windows and non-Windows
1895         [LINKLIB]: new variable, copy of UNIX-style LINK, used for linking
1896           libraries
1897         [LINK_FOR_BUILD]: new variable
1898         [OBJEXT]: use throughout
1899         [EXEEXT]: use throughout
1900         <winshared>: new target
1901         <wininstall>: new target
1902         <dftables.o>: use native compiler
1903         <dftables>: use native linker
1904         <install>: handle Windows platform correctly
1905         <clean>: ditto
1906         <check>: ditto
1907         copy DLL to top builddir before testing
1909       As part of these changes, -no-undefined was removed again. This was reported
1910       to give trouble on HP-UX 11.0, so getting rid of it seems like a good idea
1911       in any case.
1913    3. Some tidies to get rid of compiler warnings:
1915       . In the match_data structure, match_limit was an unsigned long int, whereas
1916         match_call_count was an int. I've made them both unsigned long ints.
1918       . In pcretest the fact that a const uschar * doesn't automatically cast to
1919         a void * provoked a warning.
1921       . Turning on some more compiler warnings threw up some "shadow" variables
1922         and a few more missing casts.
1924    4. If PCRE was complied with UTF-8 support, but called without the PCRE_UTF8
1925       option, a class that contained a single character with a value between 128
1926       and 255 (e.g. /[\xFF]/) caused PCRE to crash.
1928    5. If PCRE was compiled with UTF-8 support, but called without the PCRE_UTF8
1929       option, a class that contained several characters, but with at least one
1930       whose value was between 128 and 255 caused PCRE to crash.
1933    Version 4.1 12-Mar-03
1934    ---------------------
1936    1. Compiling with gcc -pedantic found a couple of places where casts were
1937    needed, and a string in dftables.c that was longer than standard compilers are
1938    required to support.
1940    2. Compiling with Sun's compiler found a few more places where the code could
1941    be tidied up in order to avoid warnings.
1943    3. The variables for cross-compiling were called HOST_CC and HOST_CFLAGS; the
1944    first of these names is deprecated in the latest Autoconf in favour of the name
1945    CC_FOR_BUILD, because "host" is typically used to mean the system on which the
1946    compiled code will be run. I can't find a reference for HOST_CFLAGS, but by
1947    analogy I have changed it to CFLAGS_FOR_BUILD.
1949    4. Added -no-undefined to the linking command in the Makefile, because this is
1950    apparently helpful for Windows. To make it work, also added "-L. -lpcre" to the
1951    linking step for the pcreposix library.
1953    5. PCRE was failing to diagnose the case of two named groups with the same
1954    name.
1956    6. A problem with one of PCRE's optimizations was discovered. PCRE remembers a
1957    literal character that is needed in the subject for a match, and scans along to
1958    ensure that it is present before embarking on the full matching process. This
1959    saves time in cases of nested unlimited repeats that are never going to match.
1960    Problem: the scan can take a lot of time if the subject is very long (e.g.
1961    megabytes), thus penalizing straightforward matches. It is now done only if the
1962    amount of subject to be scanned is less than 1000 bytes.
1964    7. A lesser problem with the same optimization is that it was recording the
1965    first character of an anchored pattern as "needed", thus provoking a search
1966    right along the subject, even when the first match of the pattern was going to
1967    fail. The "needed" character is now not set for anchored patterns, unless it
1968    follows something in the pattern that is of non-fixed length. Thus, it still
1969    fulfils its original purpose of finding quick non-matches in cases of nested
1970    unlimited repeats, but isn't used for simple anchored patterns such as /^abc/.
1973    Version 4.0 17-Feb-03
1974    ---------------------
1976    1. If a comment in an extended regex that started immediately after a meta-item
1977    extended to the end of string, PCRE compiled incorrect data. This could lead to
1978    all kinds of weird effects. Example: /#/ was bad; /()#/ was bad; /a#/ was not.
1980    2. Moved to autoconf 2.53 and libtool 1.4.2.
1982    3. Perl 5.8 no longer needs "use utf8" for doing UTF-8 things. Consequently,
1983    the special perltest8 script is no longer needed - all the tests can be run
1984    from a single perltest script.
1986    4. From 5.004, Perl has not included the VT character (0x0b) in the set defined
1987    by \s. It has now been removed in PCRE. This means it isn't recognized as
1988    whitespace in /x regexes too, which is the same as Perl. Note that the POSIX
1989    class [:space:] *does* include VT, thereby creating a mess.
1991    5. Added the class [:blank:] (a GNU extension from Perl 5.8) to match only
1992    space and tab.
1994    6. Perl 5.005 was a long time ago. It's time to amalgamate the tests that use
1995    its new features into the main test script, reducing the number of scripts.
1997    7. Perl 5.8 has changed the meaning of patterns like /a(?i)b/. Earlier versions
1998    were backward compatible, and made the (?i) apply to the whole pattern, as if
1999    /i were given. Now it behaves more logically, and applies the option setting
2000    only to what follows. PCRE has been changed to follow suit. However, if it
2001    finds options settings right at the start of the pattern, it extracts them into
2002    the global options, as before. Thus, they show up in the info data.
2004    8. Added support for the \Q...\E escape sequence. Characters in between are
2005    treated as literals. This is slightly different from Perl in that $ and @ are
2006    also handled as literals inside the quotes. In Perl, they will cause variable
2007    interpolation. Note the following examples:
2009        Pattern            PCRE matches      Perl matches
2011        \Qabc$xyz\E        abc$xyz           abc followed by the contents of $xyz
2012        \Qabc\$xyz\E       abc\$xyz          abc\$xyz
2013        \Qabc\E\$\Qxyz\E   abc$xyz           abc$xyz
2015    For compatibility with Perl, \Q...\E sequences are recognized inside character
2016    classes as well as outside them.
2018    9. Re-organized 3 code statements in pcretest to avoid "overflow in
2019    floating-point constant arithmetic" warnings from a Microsoft compiler. Added a
2020    (size_t) cast to one statement in pcretest and one in pcreposix to avoid
2021    signed/unsigned warnings.
2023    10. SunOS4 doesn't have strtoul(). This was used only for unpicking the -o
2024    option for pcretest, so I've replaced it by a simple function that does just
2025    that job.
2027    11. pcregrep was ending with code 0 instead of 2 for the commands "pcregrep" or
2028    "pcregrep -".
2030    12. Added "possessive quantifiers" ?+, *+, ++, and {,}+ which come from Sun's
2031    Java package. This provides some syntactic sugar for simple cases of what my
2032    documentation calls "once-only subpatterns". A pattern such as x*+ is the same
2033    as (?>x*). In other words, if what is inside (?>...) is just a single repeated
2034    item, you can use this simplified notation. Note that only makes sense with
2035    greedy quantifiers. Consequently, the use of the possessive quantifier forces
2036    greediness, whatever the setting of the PCRE_UNGREEDY option.
2038    13. A change of greediness default within a pattern was not taking effect at
2039    the current level for patterns like /(b+(?U)a+)/. It did apply to parenthesized
2040    subpatterns that followed. Patterns like /b+(?U)a+/ worked because the option
2041    was abstracted outside.
2043    14. PCRE now supports the \G assertion. It is true when the current matching
2044    position is at the start point of the match. This differs from \A when the
2045    starting offset is non-zero. Used with the /g option of pcretest (or similar
2046    code), it works in the same way as it does for Perl's /g option. If all
2047    alternatives of a regex begin with \G, the expression is anchored to the start
2048    match position, and the "anchored" flag is set in the compiled expression.
2050    15. Some bugs concerning the handling of certain option changes within patterns
2051    have been fixed. These applied to options other than (?ims). For example,
2052    "a(?x: b c )d" did not match "XabcdY" but did match "Xa b c dY". It should have
2053    been the other way round. Some of this was related to change 7 above.
2055    16. PCRE now gives errors for /[.x.]/ and /[=x=]/ as unsupported POSIX
2056    features, as Perl does. Previously, PCRE gave the warnings only for /[[.x.]]/
2057    and /[[=x=]]/. PCRE now also gives an error for /[:name:]/ because it supports
2058    POSIX classes only within a class (e.g. /[[:alpha:]]/).
2060    17. Added support for Perl's \C escape. This matches one byte, even in UTF8
2061    mode. Unlike ".", it always matches newline, whatever the setting of
2062    PCRE_DOTALL. However, PCRE does not permit \C to appear in lookbehind
2063    assertions. Perl allows it, but it doesn't (in general) work because it can't
2064    calculate the length of the lookbehind. At least, that's the case for Perl
2065    5.8.0 - I've been told they are going to document that it doesn't work in
2066    future.
2068    18. Added an error diagnosis for escapes that PCRE does not support: these are
2069    \L, \l, \N, \P, \p, \U, \u, and \X.
2071    19. Although correctly diagnosing a missing ']' in a character class, PCRE was
2072    reading past the end of the pattern in cases such as /[abcd/.
2074    20. PCRE was getting more memory than necessary for patterns with classes that
2075    contained both POSIX named classes and other characters, e.g. /[[:space:]abc/.
2077    21. Added some code, conditional on #ifdef VPCOMPAT, to make life easier for
2078    compiling PCRE for use with Virtual Pascal.
2080    22. Small fix to the Makefile to make it work properly if the build is done
2081    outside the source tree.
2083    23. Added a new extension: a condition to go with recursion. If a conditional
2084    subpattern starts with (?(R) the "true" branch is used if recursion has
2085    happened, whereas the "false" branch is used only at the top level.
2087    24. When there was a very long string of literal characters (over 255 bytes
2088    without UTF support, over 250 bytes with UTF support), the computation of how
2089    much memory was required could be incorrect, leading to segfaults or other
2090    strange effects.
2092    25. PCRE was incorrectly assuming anchoring (either to start of subject or to
2093    start of line for a non-DOTALL pattern) when a pattern started with (.*) and
2094    there was a subsequent back reference to those brackets. This meant that, for
2095    example, /(.*)\d+\1/ failed to match "abc123bc". Unfortunately, it isn't
2096    possible to check for precisely this case. All we can do is abandon the
2097    optimization if .* occurs inside capturing brackets when there are any back
2098    references whatsoever. (See below for a better fix that came later.)
2100    26. The handling of the optimization for finding the first character of a
2101    non-anchored pattern, and for finding a character that is required later in the
2102    match were failing in some cases. This didn't break the matching; it just
2103    failed to optimize when it could. The way this is done has been re-implemented.
2105    27. Fixed typo in error message for invalid (?R item (it said "(?p").
2107    28. Added a new feature that provides some of the functionality that Perl
2108    provides with (?{...}). The facility is termed a "callout". The way it is done
2109    in PCRE is for the caller to provide an optional function, by setting
2110    pcre_callout to its entry point. Like pcre_malloc and pcre_free, this is a
2111    global variable. By default it is unset, which disables all calling out. To get
2112    the function called, the regex must include (?C) at appropriate points. This
2113    is, in fact, equivalent to (?C0), and any number <= 255 may be given with (?C).
2114    This provides a means of identifying different callout points. When PCRE
2115    reaches such a point in the regex, if pcre_callout has been set, the external
2116    function is called. It is provided with data in a structure called
2117    pcre_callout_block, which is defined in pcre.h. If the function returns 0,
2118    matching continues; if it returns a non-zero value, the match at the current
2119    point fails. However, backtracking will occur if possible. [This was changed
2120    later and other features added - see item 49 below.]
2122    29. pcretest is upgraded to test the callout functionality. It provides a
2123    callout function that displays information. By default, it shows the start of
2124    the match and the current position in the text. There are some new data escapes
2125    to vary what happens:
2127        \C+         in addition, show current contents of captured substrings
2128        \C-         do not supply a callout function
2129        \C!n        return 1 when callout number n is reached
2130        \C!n!m      return 1 when callout number n is reached for the mth time
2132    30. If pcregrep was called with the -l option and just a single file name, it
2133    output "<stdin>" if a match was found, instead of the file name.
2135    31. Improve the efficiency of the POSIX API to PCRE. If the number of capturing
2136    slots is less than POSIX_MALLOC_THRESHOLD, use a block on the stack to pass to
2137    pcre_exec(). This saves a malloc/free per call. The default value of
2138    POSIX_MALLOC_THRESHOLD is 10; it can be changed by --with-posix-malloc-threshold
2139    when configuring.
2141    32. The default maximum size of a compiled pattern is 64K. There have been a
2142    few cases of people hitting this limit. The code now uses macros to handle the
2143    storing of links as offsets within the compiled pattern. It defaults to 2-byte
2144    links, but this can be changed to 3 or 4 bytes by --with-link-size when
2145    configuring. Tests 2 and 5 work only with 2-byte links because they output
2146    debugging information about compiled patterns.
2148    33. Internal code re-arrangements:
2150    (a) Moved the debugging function for printing out a compiled regex into
2151        its own source file (printint.c) and used #include to pull it into
2152        pcretest.c and, when DEBUG is defined, into pcre.c, instead of having two
2153        separate copies.
2155    (b) Defined the list of op-code names for debugging as a macro in
2156        internal.h so that it is next to the definition of the opcodes.
2158    (c) Defined a table of op-code lengths for simpler skipping along compiled
2159        code. This is again a macro in internal.h so that it is next to the
2160        definition of the opcodes.
2162    34. Added support for recursive calls to individual subpatterns, along the
2163    lines of Robin Houston's patch (but implemented somewhat differently).
2165    35. Further mods to the Makefile to help Win32. Also, added code to pcregrep to
2166    allow it to read and process whole directories in Win32. This code was
2167    contributed by Lionel Fourquaux; it has not been tested by me.
2169    36. Added support for named subpatterns. The Python syntax (?P<name>...) is
2170    used to name a group. Names consist of alphanumerics and underscores, and must
2171    be unique. Back references use the syntax (?P=name) and recursive calls use
2172    (?P>name) which is a PCRE extension to the Python extension. Groups still have
2173    numbers. The function pcre_fullinfo() can be used after compilation to extract
2174    a name/number map. There are three relevant calls:
2176      PCRE_INFO_NAMEENTRYSIZE        yields the size of each entry in the map
2177      PCRE_INFO_NAMECOUNT            yields the number of entries
2178      PCRE_INFO_NAMETABLE            yields a pointer to the map.
2180    The map is a vector of fixed-size entries. The size of each entry depends on
2181    the length of the longest name used. The first two bytes of each entry are the
2182    group number, most significant byte first. There follows the corresponding
2183    name, zero terminated. The names are in alphabetical order.
2185    37. Make the maximum literal string in the compiled code 250 for the non-UTF-8
2186    case instead of 255. Making it the same both with and without UTF-8 support
2187    means that the same test output works with both.
2189    38. There was a case of malloc(0) in the POSIX testing code in pcretest. Avoid
2190    calling malloc() with a zero argument.
2192    39. Change 25 above had to resort to a heavy-handed test for the .* anchoring
2193    optimization. I've improved things by keeping a bitmap of backreferences with
2194    numbers 1-31 so that if .* occurs inside capturing brackets that are not in
2195    fact referenced, the optimization can be applied. It is unlikely that a
2196    relevant occurrence of .* (i.e. one which might indicate anchoring or forcing
2197    the match to follow \n) will appear inside brackets with a number greater than
2198    31, but if it does, any back reference > 31 suppresses the optimization.
2200    40. Added a new compile-time option PCRE_NO_AUTO_CAPTURE. This has the effect
2201    of disabling numbered capturing parentheses. Any opening parenthesis that is
2202    not followed by ? behaves as if it were followed by ?: but named parentheses
2203    can still be used for capturing (and they will acquire numbers in the usual
2204    way).
2206    41. Redesigned the return codes from the match() function into yes/no/error so
2207    that errors can be passed back from deep inside the nested calls. A malloc
2208    failure while inside a recursive subpattern call now causes the
2209    PCRE_ERROR_NOMEMORY return instead of quietly going wrong.
2211    42. It is now possible to set a limit on the number of times the match()
2212    function is called in a call to pcre_exec(). This facility makes it possible to
2213    limit the amount of recursion and backtracking, though not in a directly
2214    obvious way, because the match() function is used in a number of different
2215    circumstances. The count starts from zero for each position in the subject
2216    string (for non-anchored patterns). The default limit is, for compatibility, a
2217    large number, namely 10 000 000. You can change this in two ways:
2219    (a) When configuring PCRE before making, you can use --with-match-limit=n
2220        to set a default value for the compiled library.
2222    (b) For each call to pcre_exec(), you can pass a pcre_extra block in which
2223        a different value is set. See 45 below.
2225    If the limit is exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT.
2227    43. Added a new function pcre_config(int, void *) to enable run-time extraction
2228    of things that can be changed at compile time. The first argument specifies
2229    what is wanted and the second points to where the information is to be placed.
2230    The current list of available information is:
2232      PCRE_CONFIG_UTF8
2234    The output is an integer that is set to one if UTF-8 support is available;
2235    otherwise it is set to zero.
2239    The output is an integer that it set to the value of the code that is used for
2240    newline. It is either LF (10) or CR (13).
2244    The output is an integer that contains the number of bytes used for internal
2245    linkage in compiled expressions. The value is 2, 3, or 4. See item 32 above.
2249    The output is an integer that contains the threshold above which the POSIX
2250    interface uses malloc() for output vectors. See item 31 above.
2254    The output is an unsigned integer that contains the default limit of the number
2255    of match() calls in a pcre_exec() execution. See 42 above.
2257    44. pcretest has been upgraded by the addition of the -C option. This causes it
2258    to extract all the available output from the new pcre_config() function, and to
2259    output it. The program then exits immediately.
2261    45. A need has arisen to pass over additional data with calls to pcre_exec() in
2262    order to support additional features. One way would have been to define
2263    pcre_exec2() (for example) with extra arguments, but this would not have been
2264    extensible, and would also have required all calls to the original function to
2265    be mapped to the new one. Instead, I have chosen to extend the mechanism that
2266    is used for passing in "extra" data from pcre_study().
2268    The pcre_extra structure is now exposed and defined in pcre.h. It currently
2269    contains the following fields:
2271      flags         a bitmap indicating which of the following fields are set
2272      study_data    opaque data from pcre_study()
2273      match_limit   a way of specifying a limit on match() calls for a specific
2274                      call to pcre_exec()
2275      callout_data  data for callouts (see 49 below)
2277    The flag bits are also defined in pcre.h, and are
2283    The pcre_study() function now returns one of these new pcre_extra blocks, with
2284    the actual study data pointed to by the study_data field, and the
2285    PCRE_EXTRA_STUDY_DATA flag set. This can be passed directly to pcre_exec() as
2286    before. That is, this change is entirely upwards-compatible and requires no
2287    change to existing code.
2289    If you want to pass in additional data to pcre_exec(), you can either place it
2290    in a pcre_extra block provided by pcre_study(), or create your own pcre_extra
2291    block.
2293    46. pcretest has been extended to test the PCRE_EXTRA_MATCH_LIMIT feature. If a
2294    data string contains the escape sequence \M, pcretest calls pcre_exec() several
2295    times with different match limits, until it finds the minimum value needed for
2296    pcre_exec() to complete. The value is then output. This can be instructive; for
2297    most simple matches the number is quite small, but for pathological cases it
2298    gets very large very quickly.
2300    47. There's a new option for pcre_fullinfo() called PCRE_INFO_STUDYSIZE. It
2301    returns the size of the data block pointed to by the study_data field in a
2302    pcre_extra block, that is, the value that was passed as the argument to
2303    pcre_malloc() when PCRE was getting memory in which to place the information
2304    created by pcre_study(). The fourth argument should point to a size_t variable.
2305    pcretest has been extended so that this information is shown after a successful
2306    pcre_study() call when information about the compiled regex is being displayed.
2308    48. Cosmetic change to Makefile: there's no need to have / after $(DESTDIR)
2309    because what follows is always an absolute path. (Later: it turns out that this
2310    is more than cosmetic for MinGW, because it doesn't like empty path
2311    components.)
2313    49. Some changes have been made to the callout feature (see 28 above):
2315    (i)  A callout function now has three choices for what it returns:
2317           0  =>  success, carry on matching
2318         > 0  =>  failure at this point, but backtrack if possible
2319         < 0  =>  serious error, return this value from pcre_exec()
2321         Negative values should normally be chosen from the set of PCRE_ERROR_xxx
2322         values. In particular, returning PCRE_ERROR_NOMATCH forces a standard
2323         "match failed" error. The error number PCRE_ERROR_CALLOUT is reserved for
2324         use by callout functions. It will never be used by PCRE itself.
2326    (ii) The pcre_extra structure (see 45 above) has a void * field called
2327         callout_data, with corresponding flag bit PCRE_EXTRA_CALLOUT_DATA. The
2328         pcre_callout_block structure has a field of the same name. The contents of
2329         the field passed in the pcre_extra structure are passed to the callout
2330         function in the corresponding field in the callout block. This makes it
2331         easier to use the same callout-containing regex from multiple threads. For
2332         testing, the pcretest program has a new data escape
2334           \C*n        pass the number n (may be negative) as callout_data
2336         If the callout function in pcretest receives a non-zero value as
2337         callout_data, it returns that value.
2339    50. Makefile wasn't handling CFLAGS properly when compiling dftables. Also,
2340    there were some redundant $(CFLAGS) in commands that are now specified as
2341    $(LINK), which already includes $(CFLAGS).
2343    51. Extensions to UTF-8 support are listed below. These all apply when (a) PCRE
2344    has been compiled with UTF-8 support *and* pcre_compile() has been compiled
2345    with the PCRE_UTF8 flag. Patterns that are compiled without that flag assume
2346    one-byte characters throughout. Note that case-insensitive matching applies
2347    only to characters whose values are less than 256. PCRE doesn't support the
2348    notion of cases for higher-valued characters.
2350    (i)   A character class whose characters are all within 0-255 is handled as
2351          a bit map, and the map is inverted for negative classes. Previously, a
2352          character > 255 always failed to match such a class; however it should
2353          match if the class was a negative one (e.g. [^ab]). This has been fixed.
2355    (ii)  A negated character class with a single character < 255 is coded as
2356          "not this character" (OP_NOT). This wasn't working properly when the test
2357          character was multibyte, either singly or repeated.
2359    (iii) Repeats of multibyte characters are now handled correctly in UTF-8
2360          mode, for example: \x{100}{2,3}.
2362    (iv)  The character escapes \b, \B, \d, \D, \s, \S, \w, and \W (either
2363          singly or repeated) now correctly test multibyte characters. However,
2364          PCRE doesn't recognize any characters with values greater than 255 as
2365          digits, spaces, or word characters. Such characters always match \D, \S,
2366          and \W, and never match \d, \s, or \w.
2368    (v)   Classes may now contain characters and character ranges with values
2369          greater than 255. For example: [ab\x{100}-\x{400}].
2371    (vi)  pcregrep now has a --utf-8 option (synonym -u) which makes it call
2372          PCRE in UTF-8 mode.
2374    52. The info request value PCRE_INFO_FIRSTCHAR has been renamed
2375    PCRE_INFO_FIRSTBYTE because it is a byte value. However, the old name is
2376    retained for backwards compatibility. (Note that LASTLITERAL is also a byte
2377    value.)
2379    53. The single man page has become too large. I have therefore split it up into
2380    a number of separate man pages. These also give rise to individual HTML pages;
2381    these are now put in a separate directory, and there is an index.html page that
2382    lists them all. Some hyperlinking between the pages has been installed.
2384    54. Added convenience functions for handling named capturing parentheses.
2386    55. Unknown escapes inside character classes (e.g. [\M]) and escapes that
2387    aren't interpreted therein (e.g. [\C]) are literals in Perl. This is now also
2388    true in PCRE, except when the PCRE_EXTENDED option is set, in which case they
2389    are faulted.
2391    56. Introduced HOST_CC and HOST_CFLAGS which can be set in the environment when
2392    calling configure. These values are used when compiling the dftables.c program
2393    which is run to generate the source of the default character tables. They
2394    default to the values of CC and CFLAGS. If you are cross-compiling PCRE,
2395    you will need to set these values.
2397    57. Updated the building process for Windows DLL, as provided by Fred Cox.
2400    Version 3.9 02-Jan-02
2401    ---------------------
2403    1. A bit of extraneous text had somehow crept into the pcregrep documentation.
2405    2. If --disable-static was given, the building process failed when trying to
2406    build pcretest and pcregrep. (For some reason it was using libtool to compile
2407    them, which is not right, as they aren't part of the library.)
2410    Version 3.8 18-Dec-01
2411    ---------------------
2413    1. The experimental UTF-8 code was completely screwed up. It was packing the
2414    bytes in the wrong order. How dumb can you get?
2417    Version 3.7 29-Oct-01
2418    ---------------------
2420    1. In updating pcretest to check change 1 of version 3.6, I screwed up.
2421    This caused pcretest, when used on the test data, to segfault. Unfortunately,
2422    this didn't happen under Solaris 8, where I normally test things.
2424    2. The Makefile had to be changed to make it work on BSD systems, where 'make'
2425    doesn't seem to recognize that ./xxx and xxx are the same file. (This entry
2426    isn't in ChangeLog distributed with 3.7 because I forgot when I hastily made
2427    this fix an hour or so after the initial 3.7 release.)
2430    Version 3.6 23-Oct-01
2431    ---------------------
2433    1. Crashed with /(sens|respons)e and \1ibility/ and "sense and sensibility" if
2434    offsets passed as NULL with zero offset count.
2436    2. The config.guess and config.sub files had not been updated when I moved to
2437    the latest autoconf.
2440    Version 3.5 15-Aug-01
2441    ---------------------
2443    1. Added some missing #if !defined NOPOSIX conditionals in pcretest.c that
2444    had been forgotten.
2446    2. By using declared but undefined structures, we can avoid using "void"
2447    definitions in pcre.h while keeping the internal definitions of the structures
2448    private.
2450    3. The distribution is now built using autoconf 2.50 and libtool 1.4. From a
2451    user point of view, this means that both static and shared libraries are built
2452    by default, but this can be individually controlled. More of the work of
2453    handling this static/shared cases is now inside libtool instead of PCRE's make
2454    file.
2456    4. The pcretest utility is now installed along with pcregrep because it is
2457    useful for users (to test regexs) and by doing this, it automatically gets
2458    relinked by libtool. The documentation has been turned into a man page, so
2459    there are now .1, .txt, and .html versions in /doc.
2461    5. Upgrades to pcregrep:
2462       (i)   Added long-form option names like gnu grep.
2463       (ii)  Added --help to list all options with an explanatory phrase.
2464       (iii) Added -r, --recursive to recurse into sub-directories.
2465       (iv)  Added -f, --file to read patterns from a file.
2467    6. pcre_exec() was referring to its "code" argument before testing that
2468    argument for NULL (and giving an error if it was NULL).
2470    7. Upgraded Makefile.in to allow for compiling in a different directory from
2471    the source directory.
2473    8. Tiny buglet in pcretest: when pcre_fullinfo() was called to retrieve the
2474    options bits, the pointer it was passed was to an int instead of to an unsigned
2475    long int. This mattered only on 64-bit systems.
2477    9. Fixed typo (3.4/1) in pcre.h again. Sigh. I had changed pcre.h (which is
2478    generated) instead of pcre.in, which it its source. Also made the same change
2479    in several of the .c files.
2481    10. A new release of gcc defines printf() as a macro, which broke pcretest
2482    because it had an ifdef in the middle of a string argument for printf(). Fixed
2483    by using separate calls to printf().
2485    11. Added --enable-newline-is-cr and --enable-newline-is-lf to the configure
2486    script, to force use of CR or LF instead of \n in the source. On non-Unix
2487    systems, the value can be set in config.h.
2489    12. The limit of 200 on non-capturing parentheses is a _nesting_ limit, not an
2490    absolute limit. Changed the text of the error message to make this clear, and
2491    likewise updated the man page.
2493    13. The limit of 99 on the number of capturing subpatterns has been removed.
2494    The new limit is 65535, which I hope will not be a "real" limit.
2497    Version 3.4 22-Aug-00
2498    ---------------------
2500    1. Fixed typo in pcre.h: unsigned const char * changed to const unsigned char *.
2502    2. Diagnose condition (?(0) as an error instead of crashing on matching.
2505  Version 3.3 01-Aug-00  Version 3.3 01-Aug-00
2506  ---------------------  ---------------------

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