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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
3    
4    Version 7.6 19-Jan-08
5    ---------------------
6    
7    1.  A character class containing a very large number of characters with
8        codepoints greater than 255 (in UTF-8 mode, of course) caused a buffer
9        overflow.
10    
11    2.  Patch to cut out the "long long" test in pcrecpp_unittest when
12        HAVE_LONG_LONG is not defined.
13    
14    3.  Applied Christian Ehrlicher's patch to update the CMake build files to
15        bring them up to date and include new features. This patch includes:
16    
17        - Fixed PH's badly added libz and libbz2 support.
18        - Fixed a problem with static linking.
19        - Added pcredemo.
20        - Fixed dftables problem and added an option.
21        - Added a number of HAVE_XXX tests, including HAVE_WINDOWS_H and
22            HAVE_LONG_LONG.
23        - Added readline support for pcretest.
24        - Added an listing of the option settings after cmake has run.
25    
26    
27    Version 7.5 10-Jan-08
28    ---------------------
29    
30    1.  Applied a patch from Craig: "This patch makes it possible to 'ignore'
31        values in parens when parsing an RE using the C++ wrapper."
32    
33    2.  Negative specials like \S did not work in character classes in UTF-8 mode.
34        Characters greater than 255 were excluded from the class instead of being
35        included.
36    
37    3.  The same bug as (2) above applied to negated POSIX classes such as
38        [:^space:].
39    
40    4.  PCRECPP_STATIC was referenced in pcrecpp_internal.h, but nowhere was it
41        defined or documented. It seems to have been a typo for PCRE_STATIC, so
42        I have changed it.
43    
44    5.  The construct (?&) was not diagnosed as a syntax error (it referenced the
45        first named subpattern) and a construct such as (?&a) would reference the
46        first named subpattern whose name started with "a" (in other words, the
47        length check was missing). Both these problems are fixed. "Subpattern name
48        expected" is now given for (?&) (a zero-length name), and this patch also
49        makes it give the same error for \k'' (previously it complained that that
50        was a reference to a non-existent subpattern).
51    
52    6.  The erroneous patterns (?+-a) and (?-+a) give different error messages;
53        this is right because (?- can be followed by option settings as well as by
54        digits. I have, however, made the messages clearer.
55    
56    7.  Patterns such as (?(1)a|b) (a pattern that contains fewer subpatterns
57        than the number used in the conditional) now cause a compile-time error.
58        This is actually not compatible with Perl, which accepts such patterns, but
59        treats the conditional as always being FALSE (as PCRE used to), but it
60        seems to me that giving a diagnostic is better.
61    
62    8.  Change "alphameric" to the more common word "alphanumeric" in comments
63        and messages.
64    
65    9.  Fix two occurrences of "backslash" in comments that should have been
66        "backspace".
67    
68    10. Remove two redundant lines of code that can never be obeyed (their function
69        was moved elsewhere).
70    
71    11. The program that makes PCRE's Unicode character property table had a bug
72        which caused it to generate incorrect table entries for sequences of
73        characters that have the same character type, but are in different scripts.
74        It amalgamated them into a single range, with the script of the first of
75        them. In other words, some characters were in the wrong script. There were
76        thirteen such cases, affecting characters in the following ranges:
77    
78          U+002b0 - U+002c1
79          U+0060c - U+0060d
80          U+0061e - U+00612
81          U+0064b - U+0065e
82          U+0074d - U+0076d
83          U+01800 - U+01805
84          U+01d00 - U+01d77
85          U+01d9b - U+01dbf
86          U+0200b - U+0200f
87          U+030fc - U+030fe
88          U+03260 - U+0327f
89          U+0fb46 - U+0fbb1
90          U+10450 - U+1049d
91    
92    12. The -o option (show only the matching part of a line) for pcregrep was not
93        compatible with GNU grep in that, if there was more than one match in a
94        line, it showed only the first of them. It now behaves in the same way as
95        GNU grep.
96    
97    13. If the -o and -v options were combined for pcregrep, it printed a blank
98        line for every non-matching line. GNU grep prints nothing, and pcregrep now
99        does the same. The return code can be used to tell if there were any
100        non-matching lines.
101    
102    14. Added --file-offsets and --line-offsets to pcregrep.
103    
104    15. The pattern (?=something)(?R) was not being diagnosed as a potentially
105        infinitely looping recursion. The bug was that positive lookaheads were not
106        being skipped when checking for a possible empty match (negative lookaheads
107        and both kinds of lookbehind were skipped).
108    
109    16. Fixed two typos in the Windows-only code in pcregrep.c, and moved the
110        inclusion of <windows.h> to before rather than after the definition of
111        INVALID_FILE_ATTRIBUTES (patch from David Byron).
112    
113    17. Specifying a possessive quantifier with a specific limit for a Unicode
114        character property caused pcre_compile() to compile bad code, which led at
115        runtime to PCRE_ERROR_INTERNAL (-14). Examples of patterns that caused this
116        are: /\p{Zl}{2,3}+/8 and /\p{Cc}{2}+/8. It was the possessive "+" that
117        caused the error; without that there was no problem.
118    
119    18. Added --enable-pcregrep-libz and --enable-pcregrep-libbz2.
120    
121    19. Added --enable-pcretest-libreadline.
122    
123    20. In pcrecpp.cc, the variable 'count' was incremented twice in
124        RE::GlobalReplace(). As a result, the number of replacements returned was
125        double what it should be. I removed one of the increments, but Craig sent a
126        later patch that removed the other one (the right fix) and added unit tests
127        that check the return values (which was not done before).
128    
129    21. Several CMake things:
130    
131        (1) Arranged that, when cmake is used on Unix, the libraries end up with
132            the names libpcre and libpcreposix, not just pcre and pcreposix.
133    
134        (2) The above change means that pcretest and pcregrep are now correctly
135            linked with the newly-built libraries, not previously installed ones.
136    
137        (3) Added PCRE_SUPPORT_LIBREADLINE, PCRE_SUPPORT_LIBZ, PCRE_SUPPORT_LIBBZ2.
138    
139    22. In UTF-8 mode, with newline set to "any", a pattern such as .*a.*=.b.*
140        crashed when matching a string such as a\x{2029}b (note that \x{2029} is a
141        UTF-8 newline character). The key issue is that the pattern starts .*;
142        this means that the match must be either at the beginning, or after a
143        newline. The bug was in the code for advancing after a failed match and
144        checking that the new position followed a newline. It was not taking
145        account of UTF-8 characters correctly.
146    
147    23. PCRE was behaving differently from Perl in the way it recognized POSIX
148        character classes. PCRE was not treating the sequence [:...:] as a
149        character class unless the ... were all letters. Perl, however, seems to
150        allow any characters between [: and :], though of course it rejects as
151        unknown any "names" that contain non-letters, because all the known class
152        names consist only of letters. Thus, Perl gives an error for [[:1234:]],
153        for example, whereas PCRE did not - it did not recognize a POSIX character
154        class. This seemed a bit dangerous, so the code has been changed to be
155        closer to Perl. The behaviour is not identical to Perl, because PCRE will
156        diagnose an unknown class for, for example, [[:l\ower:]] where Perl will
157        treat it as [[:lower:]]. However, PCRE does now give "unknown" errors where
158        Perl does, and where it didn't before.
159    
160    24. Rewrite so as to remove the single use of %n from pcregrep because in some
161        Windows environments %n is disabled by default.
162    
163    
164    Version 7.4 21-Sep-07
165    ---------------------
166    
167    1.  Change 7.3/28 was implemented for classes by looking at the bitmap. This
168        means that a class such as [\s] counted as "explicit reference to CR or
169        LF". That isn't really right - the whole point of the change was to try to
170        help when there was an actual mention of one of the two characters. So now
171        the change happens only if \r or \n (or a literal CR or LF) character is
172        encountered.
173    
174    2.  The 32-bit options word was also used for 6 internal flags, but the numbers
175        of both had grown to the point where there were only 3 bits left.
176        Fortunately, there was spare space in the data structure, and so I have
177        moved the internal flags into a new 16-bit field to free up more option
178        bits.
179    
180    3.  The appearance of (?J) at the start of a pattern set the DUPNAMES option,
181        but did not set the internal JCHANGED flag - either of these is enough to
182        control the way the "get" function works - but the PCRE_INFO_JCHANGED
183        facility is supposed to tell if (?J) was ever used, so now (?J) at the
184        start sets both bits.
185    
186    4.  Added options (at build time, compile time, exec time) to change \R from
187        matching any Unicode line ending sequence to just matching CR, LF, or CRLF.
188    
189    5.  doc/pcresyntax.html was missing from the distribution.
190    
191    6.  Put back the definition of PCRE_ERROR_NULLWSLIMIT, for backward
192        compatibility, even though it is no longer used.
193    
194    7.  Added macro for snprintf to pcrecpp_unittest.cc and also for strtoll and
195        strtoull to pcrecpp.cc to select the available functions in WIN32 when the
196        windows.h file is present (where different names are used). [This was
197        reversed later after testing - see 16 below.]
198    
199    8.  Changed all #include <config.h> to #include "config.h". There were also
200        some further <pcre.h> cases that I changed to "pcre.h".
201    
202    9.  When pcregrep was used with the --colour option, it missed the line ending
203        sequence off the lines that it output.
204    
205    10. It was pointed out to me that arrays of string pointers cause lots of
206        relocations when a shared library is dynamically loaded. A technique of
207        using a single long string with a table of offsets can drastically reduce
208        these. I have refactored PCRE in four places to do this. The result is
209        dramatic:
210    
211          Originally:                          290
212          After changing UCP table:            187
213          After changing error message table:   43
214          After changing table of "verbs"       36
215          After changing table of Posix names   22
216    
217        Thanks to the folks working on Gregex for glib for this insight.
218    
219    11. --disable-stack-for-recursion caused compiling to fail unless -enable-
220        unicode-properties was also set.
221    
222    12. Updated the tests so that they work when \R is defaulted to ANYCRLF.
223    
224    13. Added checks for ANY and ANYCRLF to pcrecpp.cc where it previously
225        checked only for CRLF.
226    
227    14. Added casts to pcretest.c to avoid compiler warnings.
228    
229    15. Added Craig's patch to various pcrecpp modules to avoid compiler warnings.
230    
231    16. Added Craig's patch to remove the WINDOWS_H tests, that were not working,
232        and instead check for _strtoi64 explicitly, and avoid the use of snprintf()
233        entirely. This removes changes made in 7 above.
234    
235    17. The CMake files have been updated, and there is now more information about
236        building with CMake in the NON-UNIX-USE document.
237    
238    
239    Version 7.3 28-Aug-07
240    ---------------------
241    
242     1. In the rejigging of the build system that eventually resulted in 7.1, the
243        line "#include <pcre.h>" was included in pcre_internal.h. The use of angle
244        brackets there is not right, since it causes compilers to look for an
245        installed pcre.h, not the version that is in the source that is being
246        compiled (which of course may be different). I have changed it back to:
247    
248          #include "pcre.h"
249    
250        I have a vague recollection that the change was concerned with compiling in
251        different directories, but in the new build system, that is taken care of
252        by the VPATH setting the Makefile.
253    
254     2. The pattern .*$ when run in not-DOTALL UTF-8 mode with newline=any failed
255        when the subject happened to end in the byte 0x85 (e.g. if the last
256        character was \x{1ec5}). *Character* 0x85 is one of the "any" newline
257        characters but of course it shouldn't be taken as a newline when it is part
258        of another character. The bug was that, for an unlimited repeat of . in
259        not-DOTALL UTF-8 mode, PCRE was advancing by bytes rather than by
260        characters when looking for a newline.
261    
262     3. A small performance improvement in the DOTALL UTF-8 mode .* case.
263    
264     4. Debugging: adjusted the names of opcodes for different kinds of parentheses
265        in debug output.
266    
267     5. Arrange to use "%I64d" instead of "%lld" and "%I64u" instead of "%llu" for
268        long printing in the pcrecpp unittest when running under MinGW.
269    
270     6. ESC_K was left out of the EBCDIC table.
271    
272     7. Change 7.0/38 introduced a new limit on the number of nested non-capturing
273        parentheses; I made it 1000, which seemed large enough. Unfortunately, the
274        limit also applies to "virtual nesting" when a pattern is recursive, and in
275        this case 1000 isn't so big. I have been able to remove this limit at the
276        expense of backing off one optimization in certain circumstances. Normally,
277        when pcre_exec() would call its internal match() function recursively and
278        immediately return the result unconditionally, it uses a "tail recursion"
279        feature to save stack. However, when a subpattern that can match an empty
280        string has an unlimited repetition quantifier, it no longer makes this
281        optimization. That gives it a stack frame in which to save the data for
282        checking that an empty string has been matched. Previously this was taken
283        from the 1000-entry workspace that had been reserved. So now there is no
284        explicit limit, but more stack is used.
285    
286     8. Applied Daniel's patches to solve problems with the import/export magic
287        syntax that is required for Windows, and which was going wrong for the
288        pcreposix and pcrecpp parts of the library. These were overlooked when this
289        problem was solved for the main library.
290    
291     9. There were some crude static tests to avoid integer overflow when computing
292        the size of patterns that contain repeated groups with explicit upper
293        limits. As the maximum quantifier is 65535, the maximum group length was
294        set at 30,000 so that the product of these two numbers did not overflow a
295        32-bit integer. However, it turns out that people want to use groups that
296        are longer than 30,000 bytes (though not repeat them that many times).
297        Change 7.0/17 (the refactoring of the way the pattern size is computed) has
298        made it possible to implement the integer overflow checks in a much more
299        dynamic way, which I have now done. The artificial limitation on group
300        length has been removed - we now have only the limit on the total length of
301        the compiled pattern, which depends on the LINK_SIZE setting.
302    
303    10. Fixed a bug in the documentation for get/copy named substring when
304        duplicate names are permitted. If none of the named substrings are set, the
305        functions return PCRE_ERROR_NOSUBSTRING (7); the doc said they returned an
306        empty string.
307    
308    11. Because Perl interprets \Q...\E at a high level, and ignores orphan \E
309        instances, patterns such as [\Q\E] or [\E] or even [^\E] cause an error,
310        because the ] is interpreted as the first data character and the
311        terminating ] is not found. PCRE has been made compatible with Perl in this
312        regard. Previously, it interpreted [\Q\E] as an empty class, and [\E] could
313        cause memory overwriting.
314    
315    10. Like Perl, PCRE automatically breaks an unlimited repeat after an empty
316        string has been matched (to stop an infinite loop). It was not recognizing
317        a conditional subpattern that could match an empty string if that
318        subpattern was within another subpattern. For example, it looped when
319        trying to match  (((?(1)X|))*)  but it was OK with  ((?(1)X|)*)  where the
320        condition was not nested. This bug has been fixed.
321    
322    12. A pattern like \X?\d or \P{L}?\d in non-UTF-8 mode could cause a backtrack
323        past the start of the subject in the presence of bytes with the top bit
324        set, for example "\x8aBCD".
325    
326    13. Added Perl 5.10 experimental backtracking controls (*FAIL), (*F), (*PRUNE),
327        (*SKIP), (*THEN), (*COMMIT), and (*ACCEPT).
328    
329    14. Optimized (?!) to (*FAIL).
330    
331    15. Updated the test for a valid UTF-8 string to conform to the later RFC 3629.
332        This restricts code points to be within the range 0 to 0x10FFFF, excluding
333        the "low surrogate" sequence 0xD800 to 0xDFFF. Previously, PCRE allowed the
334        full range 0 to 0x7FFFFFFF, as defined by RFC 2279. Internally, it still
335        does: it's just the validity check that is more restrictive.
336    
337    16. Inserted checks for integer overflows during escape sequence (backslash)
338        processing, and also fixed erroneous offset values for syntax errors during
339        backslash processing.
340    
341    17. Fixed another case of looking too far back in non-UTF-8 mode (cf 12 above)
342        for patterns like [\PPP\x8a]{1,}\x80 with the subject "A\x80".
343    
344    18. An unterminated class in a pattern like (?1)\c[ with a "forward reference"
345        caused an overrun.
346    
347    19. A pattern like (?:[\PPa*]*){8,} which had an "extended class" (one with
348        something other than just ASCII characters) inside a group that had an
349        unlimited repeat caused a loop at compile time (while checking to see
350        whether the group could match an empty string).
351    
352    20. Debugging a pattern containing \p or \P could cause a crash. For example,
353        [\P{Any}] did so. (Error in the code for printing property names.)
354    
355    21. An orphan \E inside a character class could cause a crash.
356    
357    22. A repeated capturing bracket such as (A)? could cause a wild memory
358        reference during compilation.
359    
360    23. There are several functions in pcre_compile() that scan along a compiled
361        expression for various reasons (e.g. to see if it's fixed length for look
362        behind). There were bugs in these functions when a repeated \p or \P was
363        present in the pattern. These operators have additional parameters compared
364        with \d, etc, and these were not being taken into account when moving along
365        the compiled data. Specifically:
366    
367        (a) A item such as \p{Yi}{3} in a lookbehind was not treated as fixed
368            length.
369    
370        (b) An item such as \pL+ within a repeated group could cause crashes or
371            loops.
372    
373        (c) A pattern such as \p{Yi}+(\P{Yi}+)(?1) could give an incorrect
374            "reference to non-existent subpattern" error.
375    
376        (d) A pattern like (\P{Yi}{2}\277)? could loop at compile time.
377    
378    24. A repeated \S or \W in UTF-8 mode could give wrong answers when multibyte
379        characters were involved (for example /\S{2}/8g with "A\x{a3}BC").
380    
381    25. Using pcregrep in multiline, inverted mode (-Mv) caused it to loop.
382    
383    26. Patterns such as [\P{Yi}A] which include \p or \P and just one other
384        character were causing crashes (broken optimization).
385    
386    27. Patterns such as (\P{Yi}*\277)* (group with possible zero repeat containing
387        \p or \P) caused a compile-time loop.
388    
389    28. More problems have arisen in unanchored patterns when CRLF is a valid line
390        break. For example, the unstudied pattern [\r\n]A does not match the string
391        "\r\nA" because change 7.0/46 below moves the current point on by two
392        characters after failing to match at the start. However, the pattern \nA
393        *does* match, because it doesn't start till \n, and if [\r\n]A is studied,
394        the same is true. There doesn't seem any very clean way out of this, but
395        what I have chosen to do makes the common cases work: PCRE now takes note
396        of whether there can be an explicit match for \r or \n anywhere in the
397        pattern, and if so, 7.0/46 no longer applies. As part of this change,
398        there's a new PCRE_INFO_HASCRORLF option for finding out whether a compiled
399        pattern has explicit CR or LF references.
400    
401    29. Added (*CR) etc for changing newline setting at start of pattern.
402    
403    
404    Version 7.2 19-Jun-07
405    ---------------------
406    
407     1. If the fr_FR locale cannot be found for test 3, try the "french" locale,
408        which is apparently normally available under Windows.
409    
410     2. Re-jig the pcregrep tests with different newline settings in an attempt
411        to make them independent of the local environment's newline setting.
412    
413     3. Add code to configure.ac to remove -g from the CFLAGS default settings.
414    
415     4. Some of the "internals" tests were previously cut out when the link size
416        was not 2, because the output contained actual offsets. The recent new
417        "Z" feature of pcretest means that these can be cut out, making the tests
418        usable with all link sizes.
419    
420     5. Implemented Stan Switzer's goto replacement for longjmp() when not using
421        stack recursion. This gives a massive performance boost under BSD, but just
422        a small improvement under Linux. However, it saves one field in the frame
423        in all cases.
424    
425     6. Added more features from the forthcoming Perl 5.10:
426    
427        (a) (?-n) (where n is a string of digits) is a relative subroutine or
428            recursion call. It refers to the nth most recently opened parentheses.
429    
430        (b) (?+n) is also a relative subroutine call; it refers to the nth next
431            to be opened parentheses.
432    
433        (c) Conditions that refer to capturing parentheses can be specified
434            relatively, for example, (?(-2)... or (?(+3)...
435    
436        (d) \K resets the start of the current match so that everything before
437            is not part of it.
438    
439        (e) \k{name} is synonymous with \k<name> and \k'name' (.NET compatible).
440    
441        (f) \g{name} is another synonym - part of Perl 5.10's unification of
442            reference syntax.
443    
444        (g) (?| introduces a group in which the numbering of parentheses in each
445            alternative starts with the same number.
446    
447        (h) \h, \H, \v, and \V match horizontal and vertical whitespace.
448    
449     7. Added two new calls to pcre_fullinfo(): PCRE_INFO_OKPARTIAL and
450        PCRE_INFO_JCHANGED.
451    
452     8. A pattern such as  (.*(.)?)*  caused pcre_exec() to fail by either not
453        terminating or by crashing. Diagnosed by Viktor Griph; it was in the code
454        for detecting groups that can match an empty string.
455    
456     9. A pattern with a very large number of alternatives (more than several
457        hundred) was running out of internal workspace during the pre-compile
458        phase, where pcre_compile() figures out how much memory will be needed. A
459        bit of new cunning has reduced the workspace needed for groups with
460        alternatives. The 1000-alternative test pattern now uses 12 bytes of
461        workspace instead of running out of the 4096 that are available.
462    
463    10. Inserted some missing (unsigned int) casts to get rid of compiler warnings.
464    
465    11. Applied patch from Google to remove an optimization that didn't quite work.
466        The report of the bug said:
467    
468          pcrecpp::RE("a*").FullMatch("aaa") matches, while
469          pcrecpp::RE("a*?").FullMatch("aaa") does not, and
470          pcrecpp::RE("a*?\\z").FullMatch("aaa") does again.
471    
472    12. If \p or \P was used in non-UTF-8 mode on a character greater than 127
473        it matched the wrong number of bytes.
474    
475    
476    Version 7.1 24-Apr-07
477    ---------------------
478    
479     1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
480        that is more "standard", making use of automake and other Autotools. There
481        is some re-arrangement of the files and adjustment of comments consequent
482        on this.
483    
484     2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
485        for recursive directory scanning broke on some systems because the files
486        are not scanned in any specific order and on different systems the order
487        was different. A call to "sort" has been inserted into RunGrepTest for the
488        approprate test as a short-term fix. In the longer term there may be an
489        alternative.
490    
491     3. I had an email from Eric Raymond about problems translating some of PCRE's
492        man pages to HTML (despite the fact that I distribute HTML pages, some
493        people do their own conversions for various reasons). The problems
494        concerned the use of low-level troff macros .br and .in. I have therefore
495        removed all such uses from the man pages (some were redundant, some could
496        be replaced by .nf/.fi pairs). The 132html script that I use to generate
497        HTML has been updated to handle .nf/.fi and to complain if it encounters
498        .br or .in.
499    
500     4. Updated comments in configure.ac that get placed in config.h.in and also
501        arranged for config.h to be included in the distribution, with the name
502        config.h.generic, for the benefit of those who have to compile without
503        Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
504    
505     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
506        Weber: (1) pcre_internal.h was missing some function renames; (2) updated
507        makevp.bat for the current PCRE, using the additional files
508        makevp_c.txt, makevp_l.txt, and pcregexp.pas.
509    
510     6. A Windows user reported a minor discrepancy with test 2, which turned out
511        to be caused by a trailing space on an input line that had got lost in his
512        copy. The trailing space was an accident, so I've just removed it.
513    
514     7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
515        that is needed.
516    
517     8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
518        as "const" (a) because they are and (b) because it helps the PHP
519        maintainers who have recently made a script to detect big data structures
520        in the php code that should be moved to the .rodata section. I remembered
521        to update Builducptable as well, so it won't revert if ucptable.h is ever
522        re-created.
523    
524     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
525        pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
526        order to be able to cut out the UTF-8 tables in the latter when UTF-8
527        support is not required. This saves 1.5-2K of code, which is important in
528        some applications.
529    
530        Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
531        so as not to refer to the tables, even though these functions will never be
532        called when UTF-8 support is disabled. Otherwise there are problems with a
533        shared library.
534    
535    10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
536    
537        (a) It was defining its arguments as char * instead of void *.
538    
539        (b) It was assuming that all moves were upwards in memory; this was true
540            a long time ago when I wrote it, but is no longer the case.
541    
542        The emulated memove() is provided for those environments that have neither
543        memmove() nor bcopy(). I didn't think anyone used it these days, but that
544        is clearly not the case, as these two bugs were recently reported.
545    
546    11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
547        and Detrail to create the HTML documentation, the .txt form of the man
548        pages, and it removes trailing spaces from listed files. It also creates
549        pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
550        case, it wraps all the #defines with #ifndefs. This script should be run
551        before "make dist".
552    
553    12. Fixed two fairly obscure bugs concerned with quantified caseless matching
554        with Unicode property support.
555    
556        (a) For a maximizing quantifier, if the two different cases of the
557            character were of different lengths in their UTF-8 codings (there are
558            some cases like this - I found 11), and the matching function had to
559            back up over a mixture of the two cases, it incorrectly assumed they
560            were both the same length.
561    
562        (b) When PCRE was configured to use the heap rather than the stack for
563            recursion during matching, it was not correctly preserving the data for
564            the other case of a UTF-8 character when checking ahead for a match
565            while processing a minimizing repeat. If the check also involved
566            matching a wide character, but failed, corruption could cause an
567            erroneous result when trying to check for a repeat of the original
568            character.
569    
570    13. Some tidying changes to the testing mechanism:
571    
572        (a) The RunTest script now detects the internal link size and whether there
573            is UTF-8 and UCP support by running ./pcretest -C instead of relying on
574            values substituted by "configure". (The RunGrepTest script already did
575            this for UTF-8.) The configure.ac script no longer substitutes the
576            relevant variables.
577    
578        (b) The debugging options /B and /D in pcretest show the compiled bytecode
579            with length and offset values. This means that the output is different
580            for different internal link sizes. Test 2 is skipped for link sizes
581            other than 2 because of this, bypassing the problem. Unfortunately,
582            there was also a test in test 3 (the locale tests) that used /B and
583            failed for link sizes other than 2. Rather than cut the whole test out,
584            I have added a new /Z option to pcretest that replaces the length and
585            offset values with spaces. This is now used to make test 3 independent
586            of link size. (Test 2 will be tidied up later.)
587    
588    14. If erroroffset was passed as NULL to pcre_compile, it provoked a
589        segmentation fault instead of returning the appropriate error message.
590    
591    15. In multiline mode when the newline sequence was set to "any", the pattern
592        ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
593        This doesn't seem right; it now treats the CRLF combination as the line
594        ending, and so does not match in that case. It's only a pattern such as ^$
595        that would hit this one: something like ^ABC$ would have failed after \r
596        and then tried again after \r\n.
597    
598    16. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
599        in an attempt to make files that differ only in their line terminators
600        compare equal. This works on Linux.
601    
602    17. Under certain error circumstances pcregrep might try to free random memory
603        as it exited. This is now fixed, thanks to valgrind.
604    
605    19. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
606        "abc\r\n\r\n", it found an unwanted second match after the second \r. This
607        was because its rules for how to advance for /g after matching an empty
608        string at the end of a line did not allow for this case. They now check for
609        it specially.
610    
611    20. pcretest is supposed to handle patterns and data of any length, by
612        extending its buffers when necessary. It was getting this wrong when the
613        buffer for a data line had to be extended.
614    
615    21. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or
616        CRLF as a newline sequence.
617    
618    22. Code for handling Unicode properties in pcre_dfa_exec() wasn't being cut
619        out by #ifdef SUPPORT_UCP. This did no harm, as it could never be used, but
620        I have nevertheless tidied it up.
621    
622    23. Added some casts to kill warnings from HP-UX ia64 compiler.
623    
624    24. Added a man page for pcre-config.
625    
626    
627    Version 7.0 19-Dec-06
628    ---------------------
629    
630     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
631        moving to gcc 4.1.1.
632    
633     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
634        sys/time.h, which is documented as needed for this function. It doesn't
635        seem to matter on Linux, but it showed up on some releases of OS X.
636    
637     3. It seems that there are systems where bytes whose values are greater than
638        127 match isprint() in the "C" locale. The "C" locale should be the
639        default when a C program starts up. In most systems, only ASCII printing
640        characters match isprint(). This difference caused the output from pcretest
641        to vary, making some of the tests fail. I have changed pcretest so that:
642    
643        (a) When it is outputting text in the compiled version of a pattern, bytes
644            other than 32-126 are always shown as hex escapes.
645    
646        (b) When it is outputting text that is a matched part of a subject string,
647            it does the same, unless a different locale has been set for the match
648            (using the /L modifier). In this case, it uses isprint() to decide.
649    
650     4. Fixed a major bug that caused incorrect computation of the amount of memory
651        required for a compiled pattern when options that changed within the
652        pattern affected the logic of the preliminary scan that determines the
653        length. The relevant options are -x, and -i in UTF-8 mode. The result was
654        that the computed length was too small. The symptoms of this bug were
655        either the PCRE error "internal error: code overflow" from pcre_compile(),
656        or a glibc crash with a message such as "pcretest: free(): invalid next
657        size (fast)". Examples of patterns that provoked this bug (shown in
658        pcretest format) are:
659    
660          /(?-x: )/x
661          /(?x)(?-x: \s*#\s*)/
662          /((?i)[\x{c0}])/8
663          /(?i:[\x{c0}])/8
664    
665        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
666        is now done differently.
667    
668     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
669        wrapper classes; (b) implement a new function in the C++ scanner that is
670        more efficient than the old way of doing things because it avoids levels of
671        recursion in the regex matching; (c) add a paragraph to the documentation
672        for the FullMatch() function.
673    
674     6. The escape sequence \n was being treated as whatever was defined as
675        "newline". Not only was this contrary to the documentation, which states
676        that \n is character 10 (hex 0A), but it also went horribly wrong when
677        "newline" was defined as CRLF. This has been fixed.
678    
679     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
680        was being set to -1 for the "end of line" case (supposedly a value that no
681        character can have). Though this value is never used (the check for end of
682        line is "zero bytes in current character"), it caused compiler complaints.
683        I've changed it to 0xffffffff.
684    
685     8. In pcre_version.c, the version string was being built by a sequence of
686        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
687        string (as it is for production releases) called a macro with an empty
688        argument. The C standard says the result of this is undefined. The gcc
689        compiler treats it as an empty string (which was what was wanted) but it is
690        reported that Visual C gives an error. The source has been hacked around to
691        avoid this problem.
692    
693     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
694        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
695        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
696        of them did).
697    
698    10. Originally, pcretest opened its input and output without "b"; then I was
699        told that "b" was needed in some environments, so it was added for release
700        5.0 to both the input and output. (It makes no difference on Unix-like
701        systems.) Later I was told that it is wrong for the input on Windows. I've
702        now abstracted the modes into two macros, to make it easier to fiddle with
703        them, and removed "b" from the input mode under Windows.
704    
705    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
706    
707    12. Added -help and --help to pcretest as an official way of being reminded
708        of the options.
709    
710    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
711        and pcrecpp.cc because they annoy compilers at high warning levels.
712    
713    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
714    
715    15. Fixed an occurrence of == in configure.ac that should have been = (shell
716        scripts are not C programs :-) and which was not noticed because it works
717        on Linux.
718    
719    16. pcretest is supposed to handle any length of pattern and data line (as one
720        line or as a continued sequence of lines) by extending its input buffer if
721        necessary. This feature was broken for very long pattern lines, leading to
722        a string of junk being passed to pcre_compile() if the pattern was longer
723        than about 50K.
724    
725    17. I have done a major re-factoring of the way pcre_compile() computes the
726        amount of memory needed for a compiled pattern. Previously, there was code
727        that made a preliminary scan of the pattern in order to do this. That was
728        OK when PCRE was new, but as the facilities have expanded, it has become
729        harder and harder to keep it in step with the real compile phase, and there
730        have been a number of bugs (see for example, 4 above). I have now found a
731        cunning way of running the real compile function in a "fake" mode that
732        enables it to compute how much memory it would need, while actually only
733        ever using a few hundred bytes of working memory and without too many
734        tests of the mode. This should make future maintenance and development
735        easier. A side effect of this work is that the limit of 200 on the nesting
736        depth of parentheses has been removed (though this was never a serious
737        limitation, I suspect). However, there is a downside: pcre_compile() now
738        runs more slowly than before (30% or more, depending on the pattern). I
739        hope this isn't a big issue. There is no effect on runtime performance.
740    
741    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
742        newline (only possible for the last line of a file) and it was a
743        pattern that set a locale (followed by /Lsomething), pcretest crashed.
744    
745    19. Added additional timing features to pcretest. (1) The -tm option now times
746        matching only, not compiling. (2) Both -t and -tm can be followed, as a
747        separate command line item, by a number that specifies the number of
748        repeats to use when timing. The default is 50000; this gives better
749        precision, but takes uncomfortably long for very large patterns.
750    
751    20. Extended pcre_study() to be more clever in cases where a branch of a
752        subpattern has no definite first character. For example, (a*|b*)[cd] would
753        previously give no result from pcre_study(). Now it recognizes that the
754        first character must be a, b, c, or d.
755    
756    21. There was an incorrect error "recursive call could loop indefinitely" if
757        a subpattern (or the entire pattern) that was being tested for matching an
758        empty string contained only one non-empty item after a nested subpattern.
759        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
760        incorrectly, because the \d was being skipped in the check.
761    
762    22. The pcretest program now has a new pattern option /B and a command line
763        option -b, which is equivalent to adding /B to every pattern. This causes
764        it to show the compiled bytecode, without the additional information that
765        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
766        is the same as /B/I).
767    
768    23. A new optimization is now able automatically to treat some sequences such
769        as a*b as a*+b. More specifically, if something simple (such as a character
770        or a simple class like \d) has an unlimited quantifier, and is followed by
771        something that cannot possibly match the quantified thing, the quantifier
772        is automatically "possessified".
773    
774    24. A recursive reference to a subpattern whose number was greater than 39
775        went wrong under certain circumstances in UTF-8 mode. This bug could also
776        have affected the operation of pcre_study().
777    
778    25. Realized that a little bit of performance could be had by replacing
779        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
780    
781    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
782    
783    27. Possessive quantifiers such as a++ were previously implemented by turning
784        them into atomic groups such as ($>a+). Now they have their own opcodes,
785        which improves performance. This includes the automatically created ones
786        from 23 above.
787    
788    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
789        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
790        the first matched character to be a colon. This applied both to named and
791        numbered groups.
792    
793    29. The ucpinternal.h header file was missing its idempotency #ifdef.
794    
795    30. I was sent a "project" file called libpcre.a.dev which I understand makes
796        building PCRE on Windows easier, so I have included it in the distribution.
797    
798    31. There is now a check in pcretest against a ridiculously large number being
799        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
800        loop, the loop is abandoned.
801    
802    32. Forward references to subpatterns in conditions such as (?(2)...) where
803        subpattern 2 is defined later cause pcre_compile() to search forwards in
804        the pattern for the relevant set of parentheses. This search went wrong
805        when there were unescaped parentheses in a character class, parentheses
806        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
807    
808    33. "Subroutine" calls and backreferences were previously restricted to
809        referencing subpatterns earlier in the regex. This restriction has now
810        been removed.
811    
812    34. Added a number of extra features that are going to be in Perl 5.10. On the
813        whole, these are just syntactic alternatives for features that PCRE had
814        previously implemented using the Python syntax or my own invention. The
815        other formats are all retained for compatibility.
816    
817        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
818            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
819            also .NET compatible.
820    
821        (b) A recursion or subroutine call to a named group can now be defined as
822            (?&name) as well as (?P>name).
823    
824        (c) A backreference to a named group can now be defined as \k<name> or
825            \k'name' as well as (?P=name). The new forms, as well as being in Perl
826            5.10, are also .NET compatible.
827    
828        (d) A conditional reference to a named group can now use the syntax
829            (?(<name>) or (?('name') as well as (?(name).
830    
831        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
832            groups (named and numbered) that are never evaluated inline, but can be
833            called as "subroutines" from elsewhere. In effect, the DEFINE condition
834            is always false. There may be only one alternative in such a group.
835    
836        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
837            as the simple (?(R). The condition is true only if the most recent
838            recursion is that of the given number or name. It does not search out
839            through the entire recursion stack.
840    
841        (g) The escape \gN or \g{N} has been added, where N is a positive or
842            negative number, specifying an absolute or relative reference.
843    
844    35. Tidied to get rid of some further signed/unsigned compiler warnings and
845        some "unreachable code" warnings.
846    
847    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
848        things, this adds five new scripts.
849    
850    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
851        There were also incompatibilities regarding the handling of \Q..\E inside
852        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
853        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
854    
855    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
856        matches an empty string, and forcibly breaks the loop. There were bugs in
857        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
858        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
859        separate and independent bugs (that affected different cases) have been
860        fixed.
861    
862    39. Refactored the code to abolish the use of different opcodes for small
863        capturing bracket numbers. This is a tidy that I avoided doing when I
864        removed the limit on the number of capturing brackets for 3.5 back in 2001.
865        The new approach is not only tidier, it makes it possible to reduce the
866        memory needed to fix the previous bug (38).
867    
868    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
869        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
870        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
871        mode.
872    
873    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
874        report.
875    
876    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
877        copy construction and assignment in the C++ wrapper.
878    
879    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
880        couple of bugs that could have given wrong results in the "--newline=crlf"
881        case.
882    
883    44. Added a number of casts and did some reorganization of signed/unsigned int
884        variables following suggestions from Dair Grant. Also renamed the variable
885        "this" as "item" because it is a C++ keyword.
886    
887    45. Arranged for dftables to add
888    
889          #include "pcre_internal.h"
890    
891        to pcre_chartables.c because without it, gcc 4.x may remove the array
892        definition from the final binary if PCRE is built into a static library and
893        dead code stripping is activated.
894    
895    46. For an unanchored pattern, if a match attempt fails at the start of a
896        newline sequence, and the newline setting is CRLF or ANY, and the next two
897        characters are CRLF, advance by two characters instead of one.
898    
899    
900    Version 6.7 04-Jul-06
901    ---------------------
902    
903     1. In order to handle tests when input lines are enormously long, pcretest has
904        been re-factored so that it automatically extends its buffers when
905        necessary. The code is crude, but this _is_ just a test program. The
906        default size has been increased from 32K to 50K.
907    
908     2. The code in pcre_study() was using the value of the re argument before
909        testing it for NULL. (Of course, in any sensible call of the function, it
910        won't be NULL.)
911    
912     3. The memmove() emulation function in pcre_internal.h, which is used on
913        systems that lack both memmove() and bcopy() - that is, hardly ever -
914        was missing a "static" storage class specifier.
915    
916     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
917        containing an extended class (one that cannot be represented by a bitmap
918        because it contains high-valued characters or Unicode property items, e.g.
919        [\pZ]). Almost always one would set UTF-8 mode when processing such a
920        pattern, but PCRE should not loop if you do not (it no longer does).
921        [Detail: two cases were found: (a) a repeated subpattern containing an
922        extended class; (b) a recursive reference to a subpattern that followed a
923        previous extended class. It wasn't skipping over the extended class
924        correctly when UTF-8 mode was not set.]
925    
926     5. A negated single-character class was not being recognized as fixed-length
927        in lookbehind assertions such as (?<=[^f]), leading to an incorrect
928        compile error "lookbehind assertion is not fixed length".
929    
930     6. The RunPerlTest auxiliary script was showing an unexpected difference
931        between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
932        write a Perl script that can interpret lines of an input file either as
933        byte characters or as UTF-8, which is what "perltest" was being required to
934        do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
935        can't do is switch easily at run time between having the "use utf8;" pragma
936        or not. In the end, I fudged it by using the RunPerlTest script to insert
937        "use utf8;" explicitly for the UTF-8 tests.
938    
939     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
940        the end of the subject string, contrary to the documentation and to what
941        Perl does. This was true of both matching functions. Now it matches only at
942        the start of the subject and immediately after *internal* newlines.
943    
944     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
945        a pointer to an int instead of a pointer to an unsigned long int. This
946        caused problems on 64-bit systems.
947    
948     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
949        instance of the 'standard' template library not being so standard".
950    
951    10. There was no check on the number of named subpatterns nor the maximum
952        length of a subpattern name. The product of these values is used to compute
953        the size of the memory block for a compiled pattern. By supplying a very
954        long subpattern name and a large number of named subpatterns, the size
955        computation could be caused to overflow. This is now prevented by limiting
956        the length of names to 32 characters, and the number of named subpatterns
957        to 10,000.
958    
959    11. Subpatterns that are repeated with specific counts have to be replicated in
960        the compiled pattern. The size of memory for this was computed from the
961        length of the subpattern and the repeat count. The latter is limited to
962        65535, but there was no limit on the former, meaning that integer overflow
963        could in principle occur. The compiled length of a repeated subpattern is
964        now limited to 30,000 bytes in order to prevent this.
965    
966    12. Added the optional facility to have named substrings with the same name.
967    
968    13. Added the ability to use a named substring as a condition, using the
969        Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
970        are numbers (not recommended). Forward references are permitted.
971    
972    14. Added forward references in named backreferences (if you see what I mean).
973    
974    15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
975        pattern could run off the end of the subject. For example, the pattern
976        "(?s)(.{1,5})"8 did this with the subject "ab".
977    
978    16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
979        PCRE_CASELESS was set when matching characters that were quantified with ?
980        or *.
981    
982    17. A character class other than a single negated character that had a minimum
983        but no maximum quantifier - for example [ab]{6,} - was not handled
984        correctly by pce_dfa_exec(). It would match only one character.
985    
986    18. A valid (though odd) pattern that looked like a POSIX character
987        class but used an invalid character after [ (for example [[,abc,]]) caused
988        pcre_compile() to give the error "Failed: internal error: code overflow" or
989        in some cases to crash with a glibc free() error. This could even happen if
990        the pattern terminated after [[ but there just happened to be a sequence of
991        letters, a binary zero, and a closing ] in the memory that followed.
992    
993    19. Perl's treatment of octal escapes in the range \400 to \777 has changed
994        over the years. Originally (before any Unicode support), just the bottom 8
995        bits were taken. Thus, for example, \500 really meant \100. Nowadays the
996        output from "man perlunicode" includes this:
997    
998          The regular expression compiler produces polymorphic opcodes.  That
999          is, the pattern adapts to the data and automatically switches to
1000          the Unicode character scheme when presented with Unicode data--or
1001          instead uses a traditional byte scheme when presented with byte
1002          data.
1003    
1004        Sadly, a wide octal escape does not cause a switch, and in a string with
1005        no other multibyte characters, these octal escapes are treated as before.
1006        Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
1007        /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
1008        Unicode string.
1009    
1010        I have not perpetrated such confusion in PCRE. Up till now, it took just
1011        the bottom 8 bits, as in old Perl. I have now made octal escapes with
1012        values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
1013        translate to the appropriate multibyte character.
1014    
1015    29. Applied some refactoring to reduce the number of warnings from Microsoft
1016        and Borland compilers. This has included removing the fudge introduced
1017        seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
1018        a warning about an unused variable.
1019    
1020    21. PCRE has not included VT (character 0x0b) in the set of whitespace
1021        characters since release 4.0, because Perl (from release 5.004) does not.
1022        [Or at least, is documented not to: some releases seem to be in conflict
1023        with the documentation.] However, when a pattern was studied with
1024        pcre_study() and all its branches started with \s, PCRE still included VT
1025        as a possible starting character. Of course, this did no harm; it just
1026        caused an unnecessary match attempt.
1027    
1028    22. Removed a now-redundant internal flag bit that recorded the fact that case
1029        dependency changed within the pattern. This was once needed for "required
1030        byte" processing, but is no longer used. This recovers a now-scarce options
1031        bit. Also moved the least significant internal flag bit to the most-
1032        significant bit of the word, which was not previously used (hangover from
1033        the days when it was an int rather than a uint) to free up another bit for
1034        the future.
1035    
1036    23. Added support for CRLF line endings as well as CR and LF. As well as the
1037        default being selectable at build time, it can now be changed at runtime
1038        via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
1039        specify that it is scanning data with non-default line endings.
1040    
1041    24. Changed the definition of CXXLINK to make it agree with the definition of
1042        LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
1043    
1044    25. Applied Ian Taylor's patches to avoid using another stack frame for tail
1045        recursions. This makes a big different to stack usage for some patterns.
1046    
1047    26. If a subpattern containing a named recursion or subroutine reference such
1048        as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
1049        the space required for the compiled pattern went wrong and gave too small a
1050        value. Depending on the environment, this could lead to "Failed: internal
1051        error: code overflow at offset 49" or "glibc detected double free or
1052        corruption" errors.
1053    
1054    27. Applied patches from Google (a) to support the new newline modes and (b) to
1055        advance over multibyte UTF-8 characters in GlobalReplace.
1056    
1057    28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
1058        difference for some implementation of PCRE in some Windows version.
1059    
1060    29. Added some extra testing facilities to pcretest:
1061    
1062        \q<number>   in a data line sets the "match limit" value
1063        \Q<number>   in a data line sets the "match recursion limt" value
1064        -S <number>  sets the stack size, where <number> is in megabytes
1065    
1066        The -S option isn't available for Windows.
1067    
1068    
1069    Version 6.6 06-Feb-06
1070    ---------------------
1071    
1072     1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
1073        in pcreposix.h. I have copied the definition from pcre.h.
1074    
1075     2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
1076        because pcre.h is no longer a built file.
1077    
1078     3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
1079        not normally included in the compiled code.
1080    
1081    
1082    Version 6.5 01-Feb-06
1083    ---------------------
1084    
1085     1. When using the partial match feature with pcre_dfa_exec(), it was not
1086        anchoring the second and subsequent partial matches at the new starting
1087        point. This could lead to incorrect results. For example, with the pattern
1088        /1234/, partially matching against "123" and then "a4" gave a match.
1089    
1090     2. Changes to pcregrep:
1091    
1092        (a) All non-match returns from pcre_exec() were being treated as failures
1093            to match the line. Now, unless the error is PCRE_ERROR_NOMATCH, an
1094            error message is output. Some extra information is given for the
1095            PCRE_ERROR_MATCHLIMIT and PCRE_ERROR_RECURSIONLIMIT errors, which are
1096            probably the only errors that are likely to be caused by users (by
1097            specifying a regex that has nested indefinite repeats, for instance).
1098            If there are more than 20 of these errors, pcregrep is abandoned.
1099    
1100        (b) A binary zero was treated as data while matching, but terminated the
1101            output line if it was written out. This has been fixed: binary zeroes
1102            are now no different to any other data bytes.
1103    
1104        (c) Whichever of the LC_ALL or LC_CTYPE environment variables is set is
1105            used to set a locale for matching. The --locale=xxxx long option has
1106            been added (no short equivalent) to specify a locale explicitly on the
1107            pcregrep command, overriding the environment variables.
1108    
1109        (d) When -B was used with -n, some line numbers in the output were one less
1110            than they should have been.
1111    
1112        (e) Added the -o (--only-matching) option.
1113    
1114        (f) If -A or -C was used with -c (count only), some lines of context were
1115            accidentally printed for the final match.
1116    
1117        (g) Added the -H (--with-filename) option.
1118    
1119        (h) The combination of options -rh failed to suppress file names for files
1120            that were found from directory arguments.
1121    
1122        (i) Added the -D (--devices) and -d (--directories) options.
1123    
1124        (j) Added the -F (--fixed-strings) option.
1125    
1126        (k) Allow "-" to be used as a file name for -f as well as for a data file.
1127    
1128        (l) Added the --colo(u)r option.
1129    
1130        (m) Added Jeffrey Friedl's -S testing option, but within #ifdefs so that it
1131            is not present by default.
1132    
1133     3. A nasty bug was discovered in the handling of recursive patterns, that is,
1134        items such as (?R) or (?1), when the recursion could match a number of
1135        alternatives. If it matched one of the alternatives, but subsequently,
1136        outside the recursion, there was a failure, the code tried to back up into
1137        the recursion. However, because of the way PCRE is implemented, this is not
1138        possible, and the result was an incorrect result from the match.
1139    
1140        In order to prevent this happening, the specification of recursion has
1141        been changed so that all such subpatterns are automatically treated as
1142        atomic groups. Thus, for example, (?R) is treated as if it were (?>(?R)).
1143    
1144     4. I had overlooked the fact that, in some locales, there are characters for
1145        which isalpha() is true but neither isupper() nor islower() are true. In
1146        the fr_FR locale, for instance, the \xAA and \xBA characters (ordmasculine
1147        and ordfeminine) are like this. This affected the treatment of \w and \W
1148        when they appeared in character classes, but not when they appeared outside
1149        a character class. The bit map for "word" characters is now created
1150        separately from the results of isalnum() instead of just taking it from the
1151        upper, lower, and digit maps. (Plus the underscore character, of course.)
1152    
1153     5. The above bug also affected the handling of POSIX character classes such as
1154        [[:alpha:]] and [[:alnum:]]. These do not have their own bit maps in PCRE's
1155        permanent tables. Instead, the bit maps for such a class were previously
1156        created as the appropriate unions of the upper, lower, and digit bitmaps.
1157        Now they are created by subtraction from the [[:word:]] class, which has
1158        its own bitmap.
1159    
1160     6. The [[:blank:]] character class matches horizontal, but not vertical space.
1161        It is created by subtracting the vertical space characters (\x09, \x0a,
1162        \x0b, \x0c) from the [[:space:]] bitmap. Previously, however, the
1163        subtraction was done in the overall bitmap for a character class, meaning
1164        that a class such as [\x0c[:blank:]] was incorrect because \x0c would not
1165        be recognized. This bug has been fixed.
1166    
1167     7. Patches from the folks at Google:
1168    
1169          (a) pcrecpp.cc: "to handle a corner case that may or may not happen in
1170          real life, but is still worth protecting against".
1171    
1172          (b) pcrecpp.cc: "corrects a bug when negative radixes are used with
1173          regular expressions".
1174    
1175          (c) pcre_scanner.cc: avoid use of std::count() because not all systems
1176          have it.
1177    
1178          (d) Split off pcrecpparg.h from pcrecpp.h and had the former built by
1179          "configure" and the latter not, in order to fix a problem somebody had
1180          with compiling the Arg class on HP-UX.
1181    
1182          (e) Improve the error-handling of the C++ wrapper a little bit.
1183    
1184          (f) New tests for checking recursion limiting.
1185    
1186     8. The pcre_memmove() function, which is used only if the environment does not
1187        have a standard memmove() function (and is therefore rarely compiled),
1188        contained two bugs: (a) use of int instead of size_t, and (b) it was not
1189        returning a result (though PCRE never actually uses the result).
1190    
1191     9. In the POSIX regexec() interface, if nmatch is specified as a ridiculously
1192        large number - greater than INT_MAX/(3*sizeof(int)) - REG_ESPACE is
1193        returned instead of calling malloc() with an overflowing number that would
1194        most likely cause subsequent chaos.
1195    
1196    10. The debugging option of pcretest was not showing the NO_AUTO_CAPTURE flag.
1197    
1198    11. The POSIX flag REG_NOSUB is now supported. When a pattern that was compiled
1199        with this option is matched, the nmatch and pmatch options of regexec() are
1200        ignored.
1201    
1202    12. Added REG_UTF8 to the POSIX interface. This is not defined by POSIX, but is
1203        provided in case anyone wants to the the POSIX interface with UTF-8
1204        strings.
1205    
1206    13. Added CXXLDFLAGS to the Makefile parameters to provide settings only on the
1207        C++ linking (needed for some HP-UX environments).
1208    
1209    14. Avoid compiler warnings in get_ucpname() when compiled without UCP support
1210        (unused parameter) and in the pcre_printint() function (omitted "default"
1211        switch label when the default is to do nothing).
1212    
1213    15. Added some code to make it possible, when PCRE is compiled as a C++
1214        library, to replace subject pointers for pcre_exec() with a smart pointer
1215        class, thus making it possible to process discontinuous strings.
1216    
1217    16. The two macros PCRE_EXPORT and PCRE_DATA_SCOPE are confusing, and perform
1218        much the same function. They were added by different people who were trying
1219        to make PCRE easy to compile on non-Unix systems. It has been suggested
1220        that PCRE_EXPORT be abolished now that there is more automatic apparatus
1221        for compiling on Windows systems. I have therefore replaced it with
1222        PCRE_DATA_SCOPE. This is set automatically for Windows; if not set it
1223        defaults to "extern" for C or "extern C" for C++, which works fine on
1224        Unix-like systems. It is now possible to override the value of PCRE_DATA_
1225        SCOPE with something explicit in config.h. In addition:
1226    
1227        (a) pcreposix.h still had just "extern" instead of either of these macros;
1228            I have replaced it with PCRE_DATA_SCOPE.
1229    
1230        (b) Functions such as _pcre_xclass(), which are internal to the library,
1231            but external in the C sense, all had PCRE_EXPORT in their definitions.
1232            This is apparently wrong for the Windows case, so I have removed it.
1233            (It makes no difference on Unix-like systems.)
1234    
1235    17. Added a new limit, MATCH_LIMIT_RECURSION, which limits the depth of nesting
1236        of recursive calls to match(). This is different to MATCH_LIMIT because
1237        that limits the total number of calls to match(), not all of which increase
1238        the depth of recursion. Limiting the recursion depth limits the amount of
1239        stack (or heap if NO_RECURSE is set) that is used. The default can be set
1240        when PCRE is compiled, and changed at run time. A patch from Google adds
1241        this functionality to the C++ interface.
1242    
1243    18. Changes to the handling of Unicode character properties:
1244    
1245        (a) Updated the table to Unicode 4.1.0.
1246    
1247        (b) Recognize characters that are not in the table as "Cn" (undefined).
1248    
1249        (c) I revised the way the table is implemented to a much improved format
1250            which includes recognition of ranges. It now supports the ranges that
1251            are defined in UnicodeData.txt, and it also amalgamates other
1252            characters into ranges. This has reduced the number of entries in the
1253            table from around 16,000 to around 3,000, thus reducing its size
1254            considerably. I realized I did not need to use a tree structure after
1255            all - a binary chop search is just as efficient. Having reduced the
1256            number of entries, I extended their size from 6 bytes to 8 bytes to
1257            allow for more data.
1258    
1259        (d) Added support for Unicode script names via properties such as \p{Han}.
1260    
1261    19. In UTF-8 mode, a backslash followed by a non-Ascii character was not
1262        matching that character.
1263    
1264    20. When matching a repeated Unicode property with a minimum greater than zero,
1265        (for example \pL{2,}), PCRE could look past the end of the subject if it
1266        reached it while seeking the minimum number of characters. This could
1267        happen only if some of the characters were more than one byte long, because
1268        there is a check for at least the minimum number of bytes.
1269    
1270    21. Refactored the implementation of \p and \P so as to be more general, to
1271        allow for more different types of property in future. This has changed the
1272        compiled form incompatibly. Anybody with saved compiled patterns that use
1273        \p or \P will have to recompile them.
1274    
1275    22. Added "Any" and "L&" to the supported property types.
1276    
1277    23. Recognize \x{...} as a code point specifier, even when not in UTF-8 mode,
1278        but give a compile time error if the value is greater than 0xff.
1279    
1280    24. The man pages for pcrepartial, pcreprecompile, and pcre_compile2 were
1281        accidentally not being installed or uninstalled.
1282    
1283    25. The pcre.h file was built from pcre.h.in, but the only changes that were
1284        made were to insert the current release number. This seemed silly, because
1285        it made things harder for people building PCRE on systems that don't run
1286        "configure". I have turned pcre.h into a distributed file, no longer built
1287        by "configure", with the version identification directly included. There is
1288        no longer a pcre.h.in file.
1289    
1290        However, this change necessitated a change to the pcre-config script as
1291        well. It is built from pcre-config.in, and one of the substitutions was the
1292        release number. I have updated configure.ac so that ./configure now finds
1293        the release number by grepping pcre.h.
1294    
1295    26. Added the ability to run the tests under valgrind.
1296    
1297    
1298    Version 6.4 05-Sep-05
1299    ---------------------
1300    
1301     1. Change 6.0/10/(l) to pcregrep introduced a bug that caused separator lines
1302        "--" to be printed when multiple files were scanned, even when none of the
1303        -A, -B, or -C options were used. This is not compatible with Gnu grep, so I
1304        consider it to be a bug, and have restored the previous behaviour.
1305    
1306     2. A couple of code tidies to get rid of compiler warnings.
1307    
1308     3. The pcretest program used to cheat by referring to symbols in the library
1309        whose names begin with _pcre_. These are internal symbols that are not
1310        really supposed to be visible externally, and in some environments it is
1311        possible to suppress them. The cheating is now confined to including
1312        certain files from the library's source, which is a bit cleaner.
1313    
1314     4. Renamed pcre.in as pcre.h.in to go with pcrecpp.h.in; it also makes the
1315        file's purpose clearer.
1316    
1317     5. Reorganized pcre_ucp_findchar().
1318    
1319    
1320    Version 6.3 15-Aug-05
1321    ---------------------
1322    
1323     1. The file libpcre.pc.in did not have general read permission in the tarball.
1324    
1325     2. There were some problems when building without C++ support:
1326    
1327        (a) If C++ support was not built, "make install" and "make test" still
1328            tried to test it.
1329    
1330        (b) There were problems when the value of CXX was explicitly set. Some
1331            changes have been made to try to fix these, and ...
1332    
1333        (c) --disable-cpp can now be used to explicitly disable C++ support.
1334    
1335        (d) The use of @CPP_OBJ@ directly caused a blank line preceded by a
1336            backslash in a target when C++ was disabled. This confuses some
1337            versions of "make", apparently. Using an intermediate variable solves
1338            this. (Same for CPP_LOBJ.)
1339    
1340     3. $(LINK_FOR_BUILD) now includes $(CFLAGS_FOR_BUILD) and $(LINK)
1341        (non-Windows) now includes $(CFLAGS) because these flags are sometimes
1342        necessary on certain architectures.
1343    
1344     4. Added a setting of -export-symbols-regex to the link command to remove
1345        those symbols that are exported in the C sense, but actually are local
1346        within the library, and not documented. Their names all begin with
1347        "_pcre_". This is not a perfect job, because (a) we have to except some
1348        symbols that pcretest ("illegally") uses, and (b) the facility isn't always
1349        available (and never for static libraries). I have made a note to try to
1350        find a way round (a) in the future.
1351    
1352    
1353    Version 6.2 01-Aug-05
1354    ---------------------
1355    
1356     1. There was no test for integer overflow of quantifier values. A construction
1357        such as {1111111111111111} would give undefined results. What is worse, if
1358        a minimum quantifier for a parenthesized subpattern overflowed and became
1359        negative, the calculation of the memory size went wrong. This could have
1360        led to memory overwriting.
1361    
1362     2. Building PCRE using VPATH was broken. Hopefully it is now fixed.
1363    
1364     3. Added "b" to the 2nd argument of fopen() in dftables.c, for non-Unix-like
1365        operating environments where this matters.
1366    
1367     4. Applied Giuseppe Maxia's patch to add additional features for controlling
1368        PCRE options from within the C++ wrapper.
1369    
1370     5. Named capturing subpatterns were not being correctly counted when a pattern
1371        was compiled. This caused two problems: (a) If there were more than 100
1372        such subpatterns, the calculation of the memory needed for the whole
1373        compiled pattern went wrong, leading to an overflow error. (b) Numerical
1374        back references of the form \12, where the number was greater than 9, were
1375        not recognized as back references, even though there were sufficient
1376        previous subpatterns.
1377    
1378     6. Two minor patches to pcrecpp.cc in order to allow it to compile on older
1379        versions of gcc, e.g. 2.95.4.
1380    
1381    
1382    Version 6.1 21-Jun-05
1383    ---------------------
1384    
1385     1. There was one reference to the variable "posix" in pcretest.c that was not
1386        surrounded by "#if !defined NOPOSIX".
1387    
1388     2. Make it possible to compile pcretest without DFA support, UTF8 support, or
1389        the cross-check on the old pcre_info() function, for the benefit of the
1390        cut-down version of PCRE that is currently imported into Exim.
1391    
1392     3. A (silly) pattern starting with (?i)(?-i) caused an internal space
1393        allocation error. I've done the easy fix, which wastes 2 bytes for sensible
1394        patterns that start (?i) but I don't think that matters. The use of (?i) is
1395        just an example; this all applies to the other options as well.
1396    
1397     4. Since libtool seems to echo the compile commands it is issuing, the output
1398        from "make" can be reduced a bit by putting "@" in front of each libtool
1399        compile command.
1400    
1401     5. Patch from the folks at Google for configure.in to be a bit more thorough
1402        in checking for a suitable C++ installation before trying to compile the
1403        C++ stuff. This should fix a reported problem when a compiler was present,
1404        but no suitable headers.
1405    
1406     6. The man pages all had just "PCRE" as their title. I have changed them to
1407        be the relevant file name. I have also arranged that these names are
1408        retained in the file doc/pcre.txt, which is a concatenation in text format
1409        of all the man pages except the little individual ones for each function.
1410    
1411     7. The NON-UNIX-USE file had not been updated for the different set of source
1412        files that come with release 6. I also added a few comments about the C++
1413        wrapper.
1414    
1415    
1416    Version 6.0 07-Jun-05
1417    ---------------------
1418    
1419     1. Some minor internal re-organization to help with my DFA experiments.
1420    
1421     2. Some missing #ifdef SUPPORT_UCP conditionals in pcretest and printint that
1422        didn't matter for the library itself when fully configured, but did matter
1423        when compiling without UCP support, or within Exim, where the ucp files are
1424        not imported.
1425    
1426     3. Refactoring of the library code to split up the various functions into
1427        different source modules. The addition of the new DFA matching code (see
1428        below) to a single monolithic source would have made it really too
1429        unwieldy, quite apart from causing all the code to be include in a
1430        statically linked application, when only some functions are used. This is
1431        relevant even without the DFA addition now that patterns can be compiled in
1432        one application and matched in another.
1433    
1434        The downside of splitting up is that there have to be some external
1435        functions and data tables that are used internally in different modules of
1436        the library but which are not part of the API. These have all had their
1437        names changed to start with "_pcre_" so that they are unlikely to clash
1438        with other external names.
1439    
1440     4. Added an alternate matching function, pcre_dfa_exec(), which matches using
1441        a different (DFA) algorithm. Although it is slower than the original
1442        function, it does have some advantages for certain types of matching
1443        problem.
1444    
1445     5. Upgrades to pcretest in order to test the features of pcre_dfa_exec(),
1446        including restarting after a partial match.
1447    
1448     6. A patch for pcregrep that defines INVALID_FILE_ATTRIBUTES if it is not
1449        defined when compiling for Windows was sent to me. I have put it into the
1450        code, though I have no means of testing or verifying it.
1451    
1452     7. Added the pcre_refcount() auxiliary function.
1453    
1454     8. Added the PCRE_FIRSTLINE option. This constrains an unanchored pattern to
1455        match before or at the first newline in the subject string. In pcretest,
1456        the /f option on a pattern can be used to set this.
1457    
1458     9. A repeated \w when used in UTF-8 mode with characters greater than 256
1459        would behave wrongly. This has been present in PCRE since release 4.0.
1460    
1461    10. A number of changes to the pcregrep command:
1462    
1463        (a) Refactored how -x works; insert ^(...)$ instead of setting
1464            PCRE_ANCHORED and checking the length, in preparation for adding
1465            something similar for -w.
1466    
1467        (b) Added the -w (match as a word) option.
1468    
1469        (c) Refactored the way lines are read and buffered so as to have more
1470            than one at a time available.
1471    
1472        (d) Implemented a pcregrep test script.
1473    
1474        (e) Added the -M (multiline match) option. This allows patterns to match
1475            over several lines of the subject. The buffering ensures that at least
1476            8K, or the rest of the document (whichever is the shorter) is available
1477            for matching (and similarly the previous 8K for lookbehind assertions).
1478    
1479        (f) Changed the --help output so that it now says
1480    
1481              -w, --word-regex(p)
1482    
1483            instead of two lines, one with "regex" and the other with "regexp"
1484            because that confused at least one person since the short forms are the
1485            same. (This required a bit of code, as the output is generated
1486            automatically from a table. It wasn't just a text change.)
1487    
1488        (g) -- can be used to terminate pcregrep options if the next thing isn't an
1489            option but starts with a hyphen. Could be a pattern or a path name
1490            starting with a hyphen, for instance.
1491    
1492        (h) "-" can be given as a file name to represent stdin.
1493    
1494        (i) When file names are being printed, "(standard input)" is used for
1495            the standard input, for compatibility with GNU grep. Previously
1496            "<stdin>" was used.
1497    
1498        (j) The option --label=xxx can be used to supply a name to be used for
1499            stdin when file names are being printed. There is no short form.
1500    
1501        (k) Re-factored the options decoding logic because we are going to add
1502            two more options that take data. Such options can now be given in four
1503            different ways, e.g. "-fname", "-f name", "--file=name", "--file name".
1504    
1505        (l) Added the -A, -B, and -C options for requesting that lines of context
1506            around matches be printed.
1507    
1508        (m) Added the -L option to print the names of files that do not contain
1509            any matching lines, that is, the complement of -l.
1510    
1511        (n) The return code is 2 if any file cannot be opened, but pcregrep does
1512            continue to scan other files.
1513    
1514        (o) The -s option was incorrectly implemented. For compatibility with other
1515            greps, it now suppresses the error message for a non-existent or non-
1516            accessible file (but not the return code). There is a new option called
1517            -q that suppresses the output of matching lines, which was what -s was
1518            previously doing.
1519    
1520        (p) Added --include and --exclude options to specify files for inclusion
1521            and exclusion when recursing.
1522    
1523    11. The Makefile was not using the Autoconf-supported LDFLAGS macro properly.
1524        Hopefully, it now does.
1525    
1526    12. Missing cast in pcre_study().
1527    
1528    13. Added an "uninstall" target to the makefile.
1529    
1530    14. Replaced "extern" in the function prototypes in Makefile.in with
1531        "PCRE_DATA_SCOPE", which defaults to 'extern' or 'extern "C"' in the Unix
1532        world, but is set differently for Windows.
1533    
1534    15. Added a second compiling function called pcre_compile2(). The only
1535        difference is that it has an extra argument, which is a pointer to an
1536        integer error code. When there is a compile-time failure, this is set
1537        non-zero, in addition to the error test pointer being set to point to an
1538        error message. The new argument may be NULL if no error number is required
1539        (but then you may as well call pcre_compile(), which is now just a
1540        wrapper). This facility is provided because some applications need a
1541        numeric error indication, but it has also enabled me to tidy up the way
1542        compile-time errors are handled in the POSIX wrapper.
1543    
1544    16. Added VPATH=.libs to the makefile; this should help when building with one
1545        prefix path and installing with another. (Or so I'm told by someone who
1546        knows more about this stuff than I do.)
1547    
1548    17. Added a new option, REG_DOTALL, to the POSIX function regcomp(). This
1549        passes PCRE_DOTALL to the pcre_compile() function, making the "." character
1550        match everything, including newlines. This is not POSIX-compatible, but
1551        somebody wanted the feature. From pcretest it can be activated by using
1552        both the P and the s flags.
1553    
1554    18. AC_PROG_LIBTOOL appeared twice in Makefile.in. Removed one.
1555    
1556    19. libpcre.pc was being incorrectly installed as executable.
1557    
1558    20. A couple of places in pcretest check for end-of-line by looking for '\n';
1559        it now also looks for '\r' so that it will work unmodified on Windows.
1560    
1561    21. Added Google's contributed C++ wrapper to the distribution.
1562    
1563    22. Added some untidy missing memory free() calls in pcretest, to keep
1564        Electric Fence happy when testing.
1565    
1566    
1567    
1568    Version 5.0 13-Sep-04
1569    ---------------------
1570    
1571     1. Internal change: literal characters are no longer packed up into items
1572        containing multiple characters in a single byte-string. Each character
1573        is now matched using a separate opcode. However, there may be more than one
1574        byte in the character in UTF-8 mode.
1575    
1576     2. The pcre_callout_block structure has two new fields: pattern_position and
1577        next_item_length. These contain the offset in the pattern to the next match
1578        item, and its length, respectively.
1579    
1580     3. The PCRE_AUTO_CALLOUT option for pcre_compile() requests the automatic
1581        insertion of callouts before each pattern item. Added the /C option to
1582        pcretest to make use of this.
1583    
1584     4. On the advice of a Windows user, the lines
1585    
1586          #if defined(_WIN32) || defined(WIN32)
1587          _setmode( _fileno( stdout ), 0x8000 );
1588          #endif  /* defined(_WIN32) || defined(WIN32) */
1589    
1590        have been added to the source of pcretest. This apparently does useful
1591        magic in relation to line terminators.
1592    
1593     5. Changed "r" and "w" in the calls to fopen() in pcretest to "rb" and "wb"
1594        for the benefit of those environments where the "b" makes a difference.
1595    
1596     6. The icc compiler has the same options as gcc, but "configure" doesn't seem
1597        to know about it. I have put a hack into configure.in that adds in code
1598        to set GCC=yes if CC=icc. This seems to end up at a point in the
1599        generated configure script that is early enough to affect the setting of
1600        compiler options, which is what is needed, but I have no means of testing
1601        whether it really works. (The user who reported this had patched the
1602        generated configure script, which of course I cannot do.)
1603    
1604        LATER: After change 22 below (new libtool files), the configure script
1605        seems to know about icc (and also ecc). Therefore, I have commented out
1606        this hack in configure.in.
1607    
1608     7. Added support for pkg-config (2 patches were sent in).
1609    
1610     8. Negated POSIX character classes that used a combination of internal tables
1611        were completely broken. These were [[:^alpha:]], [[:^alnum:]], and
1612        [[:^ascii]]. Typically, they would match almost any characters. The other
1613        POSIX classes were not broken in this way.
1614    
1615     9. Matching the pattern "\b.*?" against "ab cd", starting at offset 1, failed
1616        to find the match, as PCRE was deluded into thinking that the match had to
1617        start at the start point or following a newline. The same bug applied to
1618        patterns with negative forward assertions or any backward assertions
1619        preceding ".*" at the start, unless the pattern required a fixed first
1620        character. This was a failing pattern: "(?!.bcd).*". The bug is now fixed.
1621    
1622    10. In UTF-8 mode, when moving forwards in the subject after a failed match
1623        starting at the last subject character, bytes beyond the end of the subject
1624        string were read.
1625    
1626    11. Renamed the variable "class" as "classbits" to make life easier for C++
1627        users. (Previously there was a macro definition, but it apparently wasn't
1628        enough.)
1629    
1630    12. Added the new field "tables" to the extra data so that tables can be passed
1631        in at exec time, or the internal tables can be re-selected. This allows
1632        a compiled regex to be saved and re-used at a later time by a different
1633        program that might have everything at different addresses.
1634    
1635    13. Modified the pcre-config script so that, when run on Solaris, it shows a
1636        -R library as well as a -L library.
1637    
1638    14. The debugging options of pcretest (-d on the command line or D on a
1639        pattern) showed incorrect output for anything following an extended class
1640        that contained multibyte characters and which was followed by a quantifier.
1641    
1642    15. Added optional support for general category Unicode character properties
1643        via the \p, \P, and \X escapes. Unicode property support implies UTF-8
1644        support. It adds about 90K to the size of the library. The meanings of the
1645        inbuilt class escapes such as \d and \s have NOT been changed.
1646    
1647    16. Updated pcredemo.c to include calls to free() to release the memory for the
1648        compiled pattern.
1649    
1650    17. The generated file chartables.c was being created in the source directory
1651        instead of in the building directory. This caused the build to fail if the
1652        source directory was different from the building directory, and was
1653        read-only.
1654    
1655    18. Added some sample Win commands from Mark Tetrode into the NON-UNIX-USE
1656        file. No doubt somebody will tell me if they don't make sense... Also added
1657        Dan Mooney's comments about building on OpenVMS.
1658    
1659    19. Added support for partial matching via the PCRE_PARTIAL option for
1660        pcre_exec() and the \P data escape in pcretest.
1661    
1662    20. Extended pcretest with 3 new pattern features:
1663    
1664        (i)   A pattern option of the form ">rest-of-line" causes pcretest to
1665              write the compiled pattern to the file whose name is "rest-of-line".
1666              This is a straight binary dump of the data, with the saved pointer to
1667              the character tables forced to be NULL. The study data, if any, is
1668              written too. After writing, pcretest reads a new pattern.
1669    
1670        (ii)  If, instead of a pattern, "<rest-of-line" is given, pcretest reads a
1671              compiled pattern from the given file. There must not be any
1672              occurrences of "<" in the file name (pretty unlikely); if there are,
1673              pcretest will instead treat the initial "<" as a pattern delimiter.
1674              After reading in the pattern, pcretest goes on to read data lines as
1675              usual.
1676    
1677        (iii) The F pattern option causes pcretest to flip the bytes in the 32-bit
1678              and 16-bit fields in a compiled pattern, to simulate a pattern that
1679              was compiled on a host of opposite endianness.
1680    
1681    21. The pcre-exec() function can now cope with patterns that were compiled on
1682        hosts of opposite endianness, with this restriction:
1683    
1684          As for any compiled expression that is saved and used later, the tables
1685          pointer field cannot be preserved; the extra_data field in the arguments
1686          to pcre_exec() should be used to pass in a tables address if a value
1687          other than the default internal tables were used at compile time.
1688    
1689    22. Calling pcre_exec() with a negative value of the "ovecsize" parameter is
1690        now diagnosed as an error. Previously, most of the time, a negative number
1691        would have been treated as zero, but if in addition "ovector" was passed as
1692        NULL, a crash could occur.
1693    
1694    23. Updated the files ltmain.sh, config.sub, config.guess, and aclocal.m4 with
1695        new versions from the libtool 1.5 distribution (the last one is a copy of
1696        a file called libtool.m4). This seems to have fixed the need to patch
1697        "configure" to support Darwin 1.3 (which I used to do). However, I still
1698        had to patch ltmain.sh to ensure that ${SED} is set (it isn't on my
1699        workstation).
1700    
1701    24. Changed the PCRE licence to be the more standard "BSD" licence.
1702    
1703    
1704    Version 4.5 01-Dec-03
1705    ---------------------
1706    
1707     1. There has been some re-arrangement of the code for the match() function so
1708        that it can be compiled in a version that does not call itself recursively.
1709        Instead, it keeps those local variables that need separate instances for
1710        each "recursion" in a frame on the heap, and gets/frees frames whenever it
1711        needs to "recurse". Keeping track of where control must go is done by means
1712        of setjmp/longjmp. The whole thing is implemented by a set of macros that
1713        hide most of the details from the main code, and operates only if
1714        NO_RECURSE is defined while compiling pcre.c. If PCRE is built using the
1715        "configure" mechanism, "--disable-stack-for-recursion" turns on this way of
1716        operating.
1717    
1718        To make it easier for callers to provide specially tailored get/free
1719        functions for this usage, two new functions, pcre_stack_malloc, and
1720        pcre_stack_free, are used. They are always called in strict stacking order,
1721        and the size of block requested is always the same.
1722    
1723        The PCRE_CONFIG_STACKRECURSE info parameter can be used to find out whether
1724        PCRE has been compiled to use the stack or the heap for recursion. The
1725        -C option of pcretest uses this to show which version is compiled.
1726    
1727        A new data escape \S, is added to pcretest; it causes the amounts of store
1728        obtained and freed by both kinds of malloc/free at match time to be added
1729        to the output.
1730    
1731     2. Changed the locale test to use "fr_FR" instead of "fr" because that's
1732        what's available on my current Linux desktop machine.
1733    
1734     3. When matching a UTF-8 string, the test for a valid string at the start has
1735        been extended. If start_offset is not zero, PCRE now checks that it points
1736        to a byte that is the start of a UTF-8 character. If not, it returns
1737        PCRE_ERROR_BADUTF8_OFFSET (-11). Note: the whole string is still checked;
1738        this is necessary because there may be backward assertions in the pattern.
1739        When matching the same subject several times, it may save resources to use
1740        PCRE_NO_UTF8_CHECK on all but the first call if the string is long.
1741    
1742     4. The code for checking the validity of UTF-8 strings has been tightened so
1743        that it rejects (a) strings containing 0xfe or 0xff bytes and (b) strings
1744        containing "overlong sequences".
1745    
1746     5. Fixed a bug (appearing twice) that I could not find any way of exploiting!
1747        I had written "if ((digitab[*p++] && chtab_digit) == 0)" where the "&&"
1748        should have been "&", but it just so happened that all the cases this let
1749        through by mistake were picked up later in the function.
1750    
1751     6. I had used a variable called "isblank" - this is a C99 function, causing
1752        some compilers to warn. To avoid this, I renamed it (as "blankclass").
1753    
1754     7. Cosmetic: (a) only output another newline at the end of pcretest if it is
1755        prompting; (b) run "./pcretest /dev/null" at the start of the test script
1756        so the version is shown; (c) stop "make test" echoing "./RunTest".
1757    
1758     8. Added patches from David Burgess to enable PCRE to run on EBCDIC systems.
1759    
1760     9. The prototype for memmove() for systems that don't have it was using
1761        size_t, but the inclusion of the header that defines size_t was later. I've
1762        moved the #includes for the C headers earlier to avoid this.
1763    
1764    10. Added some adjustments to the code to make it easier to compiler on certain
1765        special systems:
1766    
1767          (a) Some "const" qualifiers were missing.
1768          (b) Added the macro EXPORT before all exported functions; by default this
1769              is defined to be empty.
1770          (c) Changed the dftables auxiliary program (that builds chartables.c) so
1771              that it reads its output file name as an argument instead of writing
1772              to the standard output and assuming this can be redirected.
1773    
1774    11. In UTF-8 mode, if a recursive reference (e.g. (?1)) followed a character
1775        class containing characters with values greater than 255, PCRE compilation
1776        went into a loop.
1777    
1778    12. A recursive reference to a subpattern that was within another subpattern
1779        that had a minimum quantifier of zero caused PCRE to crash. For example,
1780        (x(y(?2))z)? provoked this bug with a subject that got as far as the
1781        recursion. If the recursively-called subpattern itself had a zero repeat,
1782        that was OK.
1783    
1784    13. In pcretest, the buffer for reading a data line was set at 30K, but the
1785        buffer into which it was copied (for escape processing) was still set at
1786        1024, so long lines caused crashes.
1787    
1788    14. A pattern such as /[ab]{1,3}+/ failed to compile, giving the error
1789        "internal error: code overflow...". This applied to any character class
1790        that was followed by a possessive quantifier.
1791    
1792    15. Modified the Makefile to add libpcre.la as a prerequisite for
1793        libpcreposix.la because I was told this is needed for a parallel build to
1794        work.
1795    
1796    16. If a pattern that contained .* following optional items at the start was
1797        studied, the wrong optimizing data was generated, leading to matching
1798        errors. For example, studying /[ab]*.*c/ concluded, erroneously, that any
1799        matching string must start with a or b or c. The correct conclusion for
1800        this pattern is that a match can start with any character.
1801    
1802    
1803    Version 4.4 13-Aug-03
1804    ---------------------
1805    
1806     1. In UTF-8 mode, a character class containing characters with values between
1807        127 and 255 was not handled correctly if the compiled pattern was studied.
1808        In fixing this, I have also improved the studying algorithm for such
1809        classes (slightly).
1810    
1811     2. Three internal functions had redundant arguments passed to them. Removal
1812        might give a very teeny performance improvement.
1813    
1814     3. Documentation bug: the value of the capture_top field in a callout is *one
1815        more than* the number of the hightest numbered captured substring.
1816    
1817     4. The Makefile linked pcretest and pcregrep with -lpcre, which could result
1818        in incorrectly linking with a previously installed version. They now link
1819        explicitly with libpcre.la.
1820    
1821     5. configure.in no longer needs to recognize Cygwin specially.
1822    
1823     6. A problem in pcre.in for Windows platforms is fixed.
1824    
1825     7. If a pattern was successfully studied, and the -d (or /D) flag was given to
1826        pcretest, it used to include the size of the study block as part of its
1827        output. Unfortunately, the structure contains a field that has a different
1828        size on different hardware architectures. This meant that the tests that
1829        showed this size failed. As the block is currently always of a fixed size,
1830        this information isn't actually particularly useful in pcretest output, so
1831        I have just removed it.
1832    
1833     8. Three pre-processor statements accidentally did not start in column 1.
1834        Sadly, there are *still* compilers around that complain, even though
1835        standard C has not required this for well over a decade. Sigh.
1836    
1837     9. In pcretest, the code for checking callouts passed small integers in the
1838        callout_data field, which is a void * field. However, some picky compilers
1839        complained about the casts involved for this on 64-bit systems. Now
1840        pcretest passes the address of the small integer instead, which should get
1841        rid of the warnings.
1842    
1843    10. By default, when in UTF-8 mode, PCRE now checks for valid UTF-8 strings at
1844        both compile and run time, and gives an error if an invalid UTF-8 sequence
1845        is found. There is a option for disabling this check in cases where the
1846        string is known to be correct and/or the maximum performance is wanted.
1847    
1848    11. In response to a bug report, I changed one line in Makefile.in from
1849    
1850            -Wl,--out-implib,.libs/lib@WIN_PREFIX@pcreposix.dll.a \
1851        to
1852            -Wl,--out-implib,.libs/@WIN_PREFIX@libpcreposix.dll.a \
1853    
1854        to look similar to other lines, but I have no way of telling whether this
1855        is the right thing to do, as I do not use Windows. No doubt I'll get told
1856        if it's wrong...
1857    
1858    
1859    Version 4.3 21-May-03
1860    ---------------------
1861    
1862    1. Two instances of @WIN_PREFIX@ omitted from the Windows targets in the
1863       Makefile.
1864    
1865    2. Some refactoring to improve the quality of the code:
1866    
1867       (i)   The utf8_table... variables are now declared "const".
1868    
1869       (ii)  The code for \cx, which used the "case flipping" table to upper case
1870             lower case letters, now just substracts 32. This is ASCII-specific,
1871             but the whole concept of \cx is ASCII-specific, so it seems
1872             reasonable.
1873    
1874       (iii) PCRE was using its character types table to recognize decimal and
1875             hexadecimal digits in the pattern. This is silly, because it handles
1876             only 0-9, a-f, and A-F, but the character types table is locale-
1877             specific, which means strange things might happen. A private
1878             table is now used for this - though it costs 256 bytes, a table is
1879             much faster than multiple explicit tests. Of course, the standard
1880             character types table is still used for matching digits in subject
1881             strings against \d.
1882    
1883       (iv)  Strictly, the identifier ESC_t is reserved by POSIX (all identifiers
1884             ending in _t are). So I've renamed it as ESC_tee.
1885    
1886    3. The first argument for regexec() in the POSIX wrapper should have been
1887       defined as "const".
1888    
1889    4. Changed pcretest to use malloc() for its buffers so that they can be
1890       Electric Fenced for debugging.
1891    
1892    5. There were several places in the code where, in UTF-8 mode, PCRE would try
1893       to read one or more bytes before the start of the subject string. Often this
1894       had no effect on PCRE's behaviour, but in some circumstances it could
1895       provoke a segmentation fault.
1896    
1897    6. A lookbehind at the start of a pattern in UTF-8 mode could also cause PCRE
1898       to try to read one or more bytes before the start of the subject string.
1899    
1900    7. A lookbehind in a pattern matched in non-UTF-8 mode on a PCRE compiled with
1901       UTF-8 support could misbehave in various ways if the subject string
1902       contained bytes with the 0x80 bit set and the 0x40 bit unset in a lookbehind
1903       area. (PCRE was not checking for the UTF-8 mode flag, and trying to move
1904       back over UTF-8 characters.)
1905    
1906    
1907    Version 4.2 14-Apr-03
1908    ---------------------
1909    
1910    1. Typo "#if SUPPORT_UTF8" instead of "#ifdef SUPPORT_UTF8" fixed.
1911    
1912    2. Changes to the building process, supplied by Ronald Landheer-Cieslak
1913         [ON_WINDOWS]: new variable, "#" on non-Windows platforms
1914         [NOT_ON_WINDOWS]: new variable, "#" on Windows platforms
1915         [WIN_PREFIX]: new variable, "cyg" for Cygwin
1916         * Makefile.in: use autoconf substitution for OBJEXT, EXEEXT, BUILD_OBJEXT
1917           and BUILD_EXEEXT
1918         Note: automatic setting of the BUILD variables is not yet working
1919         set CPPFLAGS and BUILD_CPPFLAGS (but don't use yet) - should be used at
1920           compile-time but not at link-time
1921         [LINK]: use for linking executables only
1922         make different versions for Windows and non-Windows
1923         [LINKLIB]: new variable, copy of UNIX-style LINK, used for linking
1924           libraries
1925         [LINK_FOR_BUILD]: new variable
1926         [OBJEXT]: use throughout
1927         [EXEEXT]: use throughout
1928         <winshared>: new target
1929         <wininstall>: new target
1930         <dftables.o>: use native compiler
1931         <dftables>: use native linker
1932         <install>: handle Windows platform correctly
1933         <clean>: ditto
1934         <check>: ditto
1935         copy DLL to top builddir before testing
1936    
1937       As part of these changes, -no-undefined was removed again. This was reported
1938       to give trouble on HP-UX 11.0, so getting rid of it seems like a good idea
1939       in any case.
1940    
1941    3. Some tidies to get rid of compiler warnings:
1942    
1943       . In the match_data structure, match_limit was an unsigned long int, whereas
1944         match_call_count was an int. I've made them both unsigned long ints.
1945    
1946       . In pcretest the fact that a const uschar * doesn't automatically cast to
1947         a void * provoked a warning.
1948    
1949       . Turning on some more compiler warnings threw up some "shadow" variables
1950         and a few more missing casts.
1951    
1952    4. If PCRE was complied with UTF-8 support, but called without the PCRE_UTF8
1953       option, a class that contained a single character with a value between 128
1954       and 255 (e.g. /[\xFF]/) caused PCRE to crash.
1955    
1956    5. If PCRE was compiled with UTF-8 support, but called without the PCRE_UTF8
1957       option, a class that contained several characters, but with at least one
1958       whose value was between 128 and 255 caused PCRE to crash.
1959    
1960    
1961    Version 4.1 12-Mar-03
1962    ---------------------
1963    
1964    1. Compiling with gcc -pedantic found a couple of places where casts were
1965    needed, and a string in dftables.c that was longer than standard compilers are
1966    required to support.
1967    
1968    2. Compiling with Sun's compiler found a few more places where the code could
1969    be tidied up in order to avoid warnings.
1970    
1971    3. The variables for cross-compiling were called HOST_CC and HOST_CFLAGS; the
1972    first of these names is deprecated in the latest Autoconf in favour of the name
1973    CC_FOR_BUILD, because "host" is typically used to mean the system on which the
1974    compiled code will be run. I can't find a reference for HOST_CFLAGS, but by
1975    analogy I have changed it to CFLAGS_FOR_BUILD.
1976    
1977    4. Added -no-undefined to the linking command in the Makefile, because this is
1978    apparently helpful for Windows. To make it work, also added "-L. -lpcre" to the
1979    linking step for the pcreposix library.
1980    
1981    5. PCRE was failing to diagnose the case of two named groups with the same
1982    name.
1983    
1984    6. A problem with one of PCRE's optimizations was discovered. PCRE remembers a
1985    literal character that is needed in the subject for a match, and scans along to
1986    ensure that it is present before embarking on the full matching process. This
1987    saves time in cases of nested unlimited repeats that are never going to match.
1988    Problem: the scan can take a lot of time if the subject is very long (e.g.
1989    megabytes), thus penalizing straightforward matches. It is now done only if the
1990    amount of subject to be scanned is less than 1000 bytes.
1991    
1992    7. A lesser problem with the same optimization is that it was recording the
1993    first character of an anchored pattern as "needed", thus provoking a search
1994    right along the subject, even when the first match of the pattern was going to
1995    fail. The "needed" character is now not set for anchored patterns, unless it
1996    follows something in the pattern that is of non-fixed length. Thus, it still
1997    fulfils its original purpose of finding quick non-matches in cases of nested
1998    unlimited repeats, but isn't used for simple anchored patterns such as /^abc/.
1999    
2000    
2001    Version 4.0 17-Feb-03
2002    ---------------------
2003    
2004    1. If a comment in an extended regex that started immediately after a meta-item
2005    extended to the end of string, PCRE compiled incorrect data. This could lead to
2006    all kinds of weird effects. Example: /#/ was bad; /()#/ was bad; /a#/ was not.
2007    
2008    2. Moved to autoconf 2.53 and libtool 1.4.2.
2009    
2010    3. Perl 5.8 no longer needs "use utf8" for doing UTF-8 things. Consequently,
2011    the special perltest8 script is no longer needed - all the tests can be run
2012    from a single perltest script.
2013    
2014    4. From 5.004, Perl has not included the VT character (0x0b) in the set defined
2015    by \s. It has now been removed in PCRE. This means it isn't recognized as
2016    whitespace in /x regexes too, which is the same as Perl. Note that the POSIX
2017    class [:space:] *does* include VT, thereby creating a mess.
2018    
2019    5. Added the class [:blank:] (a GNU extension from Perl 5.8) to match only
2020    space and tab.
2021    
2022    6. Perl 5.005 was a long time ago. It's time to amalgamate the tests that use
2023    its new features into the main test script, reducing the number of scripts.
2024    
2025    7. Perl 5.8 has changed the meaning of patterns like /a(?i)b/. Earlier versions
2026    were backward compatible, and made the (?i) apply to the whole pattern, as if
2027    /i were given. Now it behaves more logically, and applies the option setting
2028    only to what follows. PCRE has been changed to follow suit. However, if it
2029    finds options settings right at the start of the pattern, it extracts them into
2030    the global options, as before. Thus, they show up in the info data.
2031    
2032    8. Added support for the \Q...\E escape sequence. Characters in between are
2033    treated as literals. This is slightly different from Perl in that $ and @ are
2034    also handled as literals inside the quotes. In Perl, they will cause variable
2035    interpolation. Note the following examples:
2036    
2037        Pattern            PCRE matches      Perl matches
2038    
2039        \Qabc$xyz\E        abc$xyz           abc followed by the contents of $xyz
2040        \Qabc\$xyz\E       abc\$xyz          abc\$xyz
2041        \Qabc\E\$\Qxyz\E   abc$xyz           abc$xyz
2042    
2043    For compatibility with Perl, \Q...\E sequences are recognized inside character
2044    classes as well as outside them.
2045    
2046    9. Re-organized 3 code statements in pcretest to avoid "overflow in
2047    floating-point constant arithmetic" warnings from a Microsoft compiler. Added a
2048    (size_t) cast to one statement in pcretest and one in pcreposix to avoid
2049    signed/unsigned warnings.
2050    
2051    10. SunOS4 doesn't have strtoul(). This was used only for unpicking the -o
2052    option for pcretest, so I've replaced it by a simple function that does just
2053    that job.
2054    
2055    11. pcregrep was ending with code 0 instead of 2 for the commands "pcregrep" or
2056    "pcregrep -".
2057    
2058    12. Added "possessive quantifiers" ?+, *+, ++, and {,}+ which come from Sun's
2059    Java package. This provides some syntactic sugar for simple cases of what my
2060    documentation calls "once-only subpatterns". A pattern such as x*+ is the same
2061    as (?>x*). In other words, if what is inside (?>...) is just a single repeated
2062    item, you can use this simplified notation. Note that only makes sense with
2063    greedy quantifiers. Consequently, the use of the possessive quantifier forces
2064    greediness, whatever the setting of the PCRE_UNGREEDY option.
2065    
2066    13. A change of greediness default within a pattern was not taking effect at
2067    the current level for patterns like /(b+(?U)a+)/. It did apply to parenthesized
2068    subpatterns that followed. Patterns like /b+(?U)a+/ worked because the option
2069    was abstracted outside.
2070    
2071    14. PCRE now supports the \G assertion. It is true when the current matching
2072    position is at the start point of the match. This differs from \A when the
2073    starting offset is non-zero. Used with the /g option of pcretest (or similar
2074    code), it works in the same way as it does for Perl's /g option. If all
2075    alternatives of a regex begin with \G, the expression is anchored to the start
2076    match position, and the "anchored" flag is set in the compiled expression.
2077    
2078    15. Some bugs concerning the handling of certain option changes within patterns
2079    have been fixed. These applied to options other than (?ims). For example,
2080    "a(?x: b c )d" did not match "XabcdY" but did match "Xa b c dY". It should have
2081    been the other way round. Some of this was related to change 7 above.
2082    
2083    16. PCRE now gives errors for /[.x.]/ and /[=x=]/ as unsupported POSIX
2084    features, as Perl does. Previously, PCRE gave the warnings only for /[[.x.]]/
2085    and /[[=x=]]/. PCRE now also gives an error for /[:name:]/ because it supports
2086    POSIX classes only within a class (e.g. /[[:alpha:]]/).
2087    
2088    17. Added support for Perl's \C escape. This matches one byte, even in UTF8
2089    mode. Unlike ".", it always matches newline, whatever the setting of
2090    PCRE_DOTALL. However, PCRE does not permit \C to appear in lookbehind
2091    assertions. Perl allows it, but it doesn't (in general) work because it can't
2092    calculate the length of the lookbehind. At least, that's the case for Perl
2093    5.8.0 - I've been told they are going to document that it doesn't work in
2094    future.
2095    
2096    18. Added an error diagnosis for escapes that PCRE does not support: these are
2097    \L, \l, \N, \P, \p, \U, \u, and \X.
2098    
2099    19. Although correctly diagnosing a missing ']' in a character class, PCRE was
2100    reading past the end of the pattern in cases such as /[abcd/.
2101    
2102    20. PCRE was getting more memory than necessary for patterns with classes that
2103    contained both POSIX named classes and other characters, e.g. /[[:space:]abc/.
2104    
2105    21. Added some code, conditional on #ifdef VPCOMPAT, to make life easier for
2106    compiling PCRE for use with Virtual Pascal.
2107    
2108    22. Small fix to the Makefile to make it work properly if the build is done
2109    outside the source tree.
2110    
2111    23. Added a new extension: a condition to go with recursion. If a conditional
2112    subpattern starts with (?(R) the "true" branch is used if recursion has
2113    happened, whereas the "false" branch is used only at the top level.
2114    
2115    24. When there was a very long string of literal characters (over 255 bytes
2116    without UTF support, over 250 bytes with UTF support), the computation of how
2117    much memory was required could be incorrect, leading to segfaults or other
2118    strange effects.
2119    
2120    25. PCRE was incorrectly assuming anchoring (either to start of subject or to
2121    start of line for a non-DOTALL pattern) when a pattern started with (.*) and
2122    there was a subsequent back reference to those brackets. This meant that, for
2123    example, /(.*)\d+\1/ failed to match "abc123bc". Unfortunately, it isn't
2124    possible to check for precisely this case. All we can do is abandon the
2125    optimization if .* occurs inside capturing brackets when there are any back
2126    references whatsoever. (See below for a better fix that came later.)
2127    
2128    26. The handling of the optimization for finding the first character of a
2129    non-anchored pattern, and for finding a character that is required later in the
2130    match were failing in some cases. This didn't break the matching; it just
2131    failed to optimize when it could. The way this is done has been re-implemented.
2132    
2133    27. Fixed typo in error message for invalid (?R item (it said "(?p").
2134    
2135    28. Added a new feature that provides some of the functionality that Perl
2136    provides with (?{...}). The facility is termed a "callout". The way it is done
2137    in PCRE is for the caller to provide an optional function, by setting
2138    pcre_callout to its entry point. Like pcre_malloc and pcre_free, this is a
2139    global variable. By default it is unset, which disables all calling out. To get
2140    the function called, the regex must include (?C) at appropriate points. This
2141    is, in fact, equivalent to (?C0), and any number <= 255 may be given with (?C).
2142    This provides a means of identifying different callout points. When PCRE
2143    reaches such a point in the regex, if pcre_callout has been set, the external
2144    function is called. It is provided with data in a structure called
2145    pcre_callout_block, which is defined in pcre.h. If the function returns 0,
2146    matching continues; if it returns a non-zero value, the match at the current
2147    point fails. However, backtracking will occur if possible. [This was changed
2148    later and other features added - see item 49 below.]
2149    
2150    29. pcretest is upgraded to test the callout functionality. It provides a
2151    callout function that displays information. By default, it shows the start of
2152    the match and the current position in the text. There are some new data escapes
2153    to vary what happens:
2154    
2155        \C+         in addition, show current contents of captured substrings
2156        \C-         do not supply a callout function
2157        \C!n        return 1 when callout number n is reached
2158        \C!n!m      return 1 when callout number n is reached for the mth time
2159    
2160    30. If pcregrep was called with the -l option and just a single file name, it
2161    output "<stdin>" if a match was found, instead of the file name.
2162    
2163    31. Improve the efficiency of the POSIX API to PCRE. If the number of capturing
2164    slots is less than POSIX_MALLOC_THRESHOLD, use a block on the stack to pass to
2165    pcre_exec(). This saves a malloc/free per call. The default value of
2166    POSIX_MALLOC_THRESHOLD is 10; it can be changed by --with-posix-malloc-threshold
2167    when configuring.
2168    
2169    32. The default maximum size of a compiled pattern is 64K. There have been a
2170    few cases of people hitting this limit. The code now uses macros to handle the
2171    storing of links as offsets within the compiled pattern. It defaults to 2-byte
2172    links, but this can be changed to 3 or 4 bytes by --with-link-size when
2173    configuring. Tests 2 and 5 work only with 2-byte links because they output
2174    debugging information about compiled patterns.
2175    
2176    33. Internal code re-arrangements:
2177    
2178    (a) Moved the debugging function for printing out a compiled regex into
2179        its own source file (printint.c) and used #include to pull it into
2180        pcretest.c and, when DEBUG is defined, into pcre.c, instead of having two
2181        separate copies.
2182    
2183    (b) Defined the list of op-code names for debugging as a macro in
2184        internal.h so that it is next to the definition of the opcodes.
2185    
2186    (c) Defined a table of op-code lengths for simpler skipping along compiled
2187        code. This is again a macro in internal.h so that it is next to the
2188        definition of the opcodes.
2189    
2190    34. Added support for recursive calls to individual subpatterns, along the
2191    lines of Robin Houston's patch (but implemented somewhat differently).
2192    
2193    35. Further mods to the Makefile to help Win32. Also, added code to pcregrep to
2194    allow it to read and process whole directories in Win32. This code was
2195    contributed by Lionel Fourquaux; it has not been tested by me.
2196    
2197    36. Added support for named subpatterns. The Python syntax (?P<name>...) is
2198    used to name a group. Names consist of alphanumerics and underscores, and must
2199    be unique. Back references use the syntax (?P=name) and recursive calls use
2200    (?P>name) which is a PCRE extension to the Python extension. Groups still have
2201    numbers. The function pcre_fullinfo() can be used after compilation to extract
2202    a name/number map. There are three relevant calls:
2203    
2204      PCRE_INFO_NAMEENTRYSIZE        yields the size of each entry in the map
2205      PCRE_INFO_NAMECOUNT            yields the number of entries
2206      PCRE_INFO_NAMETABLE            yields a pointer to the map.
2207    
2208    The map is a vector of fixed-size entries. The size of each entry depends on
2209    the length of the longest name used. The first two bytes of each entry are the
2210    group number, most significant byte first. There follows the corresponding
2211    name, zero terminated. The names are in alphabetical order.
2212    
2213    37. Make the maximum literal string in the compiled code 250 for the non-UTF-8
2214    case instead of 255. Making it the same both with and without UTF-8 support
2215    means that the same test output works with both.
2216    
2217    38. There was a case of malloc(0) in the POSIX testing code in pcretest. Avoid
2218    calling malloc() with a zero argument.
2219    
2220    39. Change 25 above had to resort to a heavy-handed test for the .* anchoring
2221    optimization. I've improved things by keeping a bitmap of backreferences with
2222    numbers 1-31 so that if .* occurs inside capturing brackets that are not in
2223    fact referenced, the optimization can be applied. It is unlikely that a
2224    relevant occurrence of .* (i.e. one which might indicate anchoring or forcing
2225    the match to follow \n) will appear inside brackets with a number greater than
2226    31, but if it does, any back reference > 31 suppresses the optimization.
2227    
2228    40. Added a new compile-time option PCRE_NO_AUTO_CAPTURE. This has the effect
2229    of disabling numbered capturing parentheses. Any opening parenthesis that is
2230    not followed by ? behaves as if it were followed by ?: but named parentheses
2231    can still be used for capturing (and they will acquire numbers in the usual
2232    way).
2233    
2234    41. Redesigned the return codes from the match() function into yes/no/error so
2235    that errors can be passed back from deep inside the nested calls. A malloc
2236    failure while inside a recursive subpattern call now causes the
2237    PCRE_ERROR_NOMEMORY return instead of quietly going wrong.
2238    
2239    42. It is now possible to set a limit on the number of times the match()
2240    function is called in a call to pcre_exec(). This facility makes it possible to
2241    limit the amount of recursion and backtracking, though not in a directly
2242    obvious way, because the match() function is used in a number of different
2243    circumstances. The count starts from zero for each position in the subject
2244    string (for non-anchored patterns). The default limit is, for compatibility, a
2245    large number, namely 10 000 000. You can change this in two ways:
2246    
2247    (a) When configuring PCRE before making, you can use --with-match-limit=n
2248        to set a default value for the compiled library.
2249    
2250    (b) For each call to pcre_exec(), you can pass a pcre_extra block in which
2251        a different value is set. See 45 below.
2252    
2253    If the limit is exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT.
2254    
2255    43. Added a new function pcre_config(int, void *) to enable run-time extraction
2256    of things that can be changed at compile time. The first argument specifies
2257    what is wanted and the second points to where the information is to be placed.
2258    The current list of available information is:
2259    
2260      PCRE_CONFIG_UTF8
2261    
2262    The output is an integer that is set to one if UTF-8 support is available;
2263    otherwise it is set to zero.
2264    
2265      PCRE_CONFIG_NEWLINE
2266    
2267    The output is an integer that it set to the value of the code that is used for
2268    newline. It is either LF (10) or CR (13).
2269    
2270      PCRE_CONFIG_LINK_SIZE
2271    
2272    The output is an integer that contains the number of bytes used for internal
2273    linkage in compiled expressions. The value is 2, 3, or 4. See item 32 above.
2274    
2275      PCRE_CONFIG_POSIX_MALLOC_THRESHOLD
2276    
2277    The output is an integer that contains the threshold above which the POSIX
2278    interface uses malloc() for output vectors. See item 31 above.
2279    
2280      PCRE_CONFIG_MATCH_LIMIT
2281    
2282    The output is an unsigned integer that contains the default limit of the number
2283    of match() calls in a pcre_exec() execution. See 42 above.
2284    
2285    44. pcretest has been upgraded by the addition of the -C option. This causes it
2286    to extract all the available output from the new pcre_config() function, and to
2287    output it. The program then exits immediately.
2288    
2289    45. A need has arisen to pass over additional data with calls to pcre_exec() in
2290    order to support additional features. One way would have been to define
2291    pcre_exec2() (for example) with extra arguments, but this would not have been
2292    extensible, and would also have required all calls to the original function to
2293    be mapped to the new one. Instead, I have chosen to extend the mechanism that
2294    is used for passing in "extra" data from pcre_study().
2295    
2296    The pcre_extra structure is now exposed and defined in pcre.h. It currently
2297    contains the following fields:
2298    
2299      flags         a bitmap indicating which of the following fields are set
2300      study_data    opaque data from pcre_study()
2301      match_limit   a way of specifying a limit on match() calls for a specific
2302                      call to pcre_exec()
2303      callout_data  data for callouts (see 49 below)
2304    
2305    The flag bits are also defined in pcre.h, and are
2306    
2307      PCRE_EXTRA_STUDY_DATA
2308      PCRE_EXTRA_MATCH_LIMIT
2309      PCRE_EXTRA_CALLOUT_DATA
2310    
2311    The pcre_study() function now returns one of these new pcre_extra blocks, with
2312    the actual study data pointed to by the study_data field, and the
2313    PCRE_EXTRA_STUDY_DATA flag set. This can be passed directly to pcre_exec() as
2314    before. That is, this change is entirely upwards-compatible and requires no
2315    change to existing code.
2316    
2317    If you want to pass in additional data to pcre_exec(), you can either place it
2318    in a pcre_extra block provided by pcre_study(), or create your own pcre_extra
2319    block.
2320    
2321    46. pcretest has been extended to test the PCRE_EXTRA_MATCH_LIMIT feature. If a
2322    data string contains the escape sequence \M, pcretest calls pcre_exec() several
2323    times with different match limits, until it finds the minimum value needed for
2324    pcre_exec() to complete. The value is then output. This can be instructive; for
2325    most simple matches the number is quite small, but for pathological cases it
2326    gets very large very quickly.
2327    
2328    47. There's a new option for pcre_fullinfo() called PCRE_INFO_STUDYSIZE. It
2329    returns the size of the data block pointed to by the study_data field in a
2330    pcre_extra block, that is, the value that was passed as the argument to
2331    pcre_malloc() when PCRE was getting memory in which to place the information
2332    created by pcre_study(). The fourth argument should point to a size_t variable.
2333    pcretest has been extended so that this information is shown after a successful
2334    pcre_study() call when information about the compiled regex is being displayed.
2335    
2336    48. Cosmetic change to Makefile: there's no need to have / after $(DESTDIR)
2337    because what follows is always an absolute path. (Later: it turns out that this
2338    is more than cosmetic for MinGW, because it doesn't like empty path
2339    components.)
2340    
2341    49. Some changes have been made to the callout feature (see 28 above):
2342    
2343    (i)  A callout function now has three choices for what it returns:
2344    
2345           0  =>  success, carry on matching
2346         > 0  =>  failure at this point, but backtrack if possible
2347         < 0  =>  serious error, return this value from pcre_exec()
2348    
2349         Negative values should normally be chosen from the set of PCRE_ERROR_xxx
2350         values. In particular, returning PCRE_ERROR_NOMATCH forces a standard
2351         "match failed" error. The error number PCRE_ERROR_CALLOUT is reserved for
2352         use by callout functions. It will never be used by PCRE itself.
2353    
2354    (ii) The pcre_extra structure (see 45 above) has a void * field called
2355         callout_data, with corresponding flag bit PCRE_EXTRA_CALLOUT_DATA. The
2356         pcre_callout_block structure has a field of the same name. The contents of
2357         the field passed in the pcre_extra structure are passed to the callout
2358         function in the corresponding field in the callout block. This makes it
2359         easier to use the same callout-containing regex from multiple threads. For
2360         testing, the pcretest program has a new data escape
2361    
2362           \C*n        pass the number n (may be negative) as callout_data
2363    
2364         If the callout function in pcretest receives a non-zero value as
2365         callout_data, it returns that value.
2366    
2367    50. Makefile wasn't handling CFLAGS properly when compiling dftables. Also,
2368    there were some redundant $(CFLAGS) in commands that are now specified as
2369    $(LINK), which already includes $(CFLAGS).
2370    
2371    51. Extensions to UTF-8 support are listed below. These all apply when (a) PCRE
2372    has been compiled with UTF-8 support *and* pcre_compile() has been compiled
2373    with the PCRE_UTF8 flag. Patterns that are compiled without that flag assume
2374    one-byte characters throughout. Note that case-insensitive matching applies
2375    only to characters whose values are less than 256. PCRE doesn't support the
2376    notion of cases for higher-valued characters.
2377    
2378    (i)   A character class whose characters are all within 0-255 is handled as
2379          a bit map, and the map is inverted for negative classes. Previously, a
2380          character > 255 always failed to match such a class; however it should
2381          match if the class was a negative one (e.g. [^ab]). This has been fixed.
2382    
2383    (ii)  A negated character class with a single character < 255 is coded as
2384          "not this character" (OP_NOT). This wasn't working properly when the test
2385          character was multibyte, either singly or repeated.
2386    
2387    (iii) Repeats of multibyte characters are now handled correctly in UTF-8
2388          mode, for example: \x{100}{2,3}.
2389    
2390    (iv)  The character escapes \b, \B, \d, \D, \s, \S, \w, and \W (either
2391          singly or repeated) now correctly test multibyte characters. However,
2392          PCRE doesn't recognize any characters with values greater than 255 as
2393          digits, spaces, or word characters. Such characters always match \D, \S,
2394          and \W, and never match \d, \s, or \w.
2395    
2396    (v)   Classes may now contain characters and character ranges with values
2397          greater than 255. For example: [ab\x{100}-\x{400}].
2398    
2399    (vi)  pcregrep now has a --utf-8 option (synonym -u) which makes it call
2400          PCRE in UTF-8 mode.
2401    
2402    52. The info request value PCRE_INFO_FIRSTCHAR has been renamed
2403    PCRE_INFO_FIRSTBYTE because it is a byte value. However, the old name is
2404    retained for backwards compatibility. (Note that LASTLITERAL is also a byte
2405    value.)
2406    
2407    53. The single man page has become too large. I have therefore split it up into
2408    a number of separate man pages. These also give rise to individual HTML pages;
2409    these are now put in a separate directory, and there is an index.html page that
2410    lists them all. Some hyperlinking between the pages has been installed.
2411    
2412    54. Added convenience functions for handling named capturing parentheses.
2413    
2414    55. Unknown escapes inside character classes (e.g. [\M]) and escapes that
2415    aren't interpreted therein (e.g. [\C]) are literals in Perl. This is now also
2416    true in PCRE, except when the PCRE_EXTENDED option is set, in which case they
2417    are faulted.
2418    
2419    56. Introduced HOST_CC and HOST_CFLAGS which can be set in the environment when
2420    calling configure. These values are used when compiling the dftables.c program
2421    which is run to generate the source of the default character tables. They
2422    default to the values of CC and CFLAGS. If you are cross-compiling PCRE,
2423    you will need to set these values.
2424    
2425    57. Updated the building process for Windows DLL, as provided by Fred Cox.
2426    
2427    
2428    Version 3.9 02-Jan-02
2429    ---------------------
2430    
2431    1. A bit of extraneous text had somehow crept into the pcregrep documentation.
2432    
2433    2. If --disable-static was given, the building process failed when trying to
2434    build pcretest and pcregrep. (For some reason it was using libtool to compile
2435    them, which is not right, as they aren't part of the library.)
2436    
2437    
2438    Version 3.8 18-Dec-01
2439    ---------------------
2440    
2441    1. The experimental UTF-8 code was completely screwed up. It was packing the
2442    bytes in the wrong order. How dumb can you get?
2443    
2444    
2445    Version 3.7 29-Oct-01
2446    ---------------------
2447    
2448    1. In updating pcretest to check change 1 of version 3.6, I screwed up.
2449    This caused pcretest, when used on the test data, to segfault. Unfortunately,
2450    this didn't happen under Solaris 8, where I normally test things.
2451    
2452    2. The Makefile had to be changed to make it work on BSD systems, where 'make'
2453    doesn't seem to recognize that ./xxx and xxx are the same file. (This entry
2454    isn't in ChangeLog distributed with 3.7 because I forgot when I hastily made
2455    this fix an hour or so after the initial 3.7 release.)
2456    
2457    
2458    Version 3.6 23-Oct-01
2459    ---------------------
2460    
2461    1. Crashed with /(sens|respons)e and \1ibility/ and "sense and sensibility" if
2462    offsets passed as NULL with zero offset count.
2463    
2464    2. The config.guess and config.sub files had not been updated when I moved to
2465    the latest autoconf.
2466    
2467    
2468    Version 3.5 15-Aug-01
2469    ---------------------
2470    
2471    1. Added some missing #if !defined NOPOSIX conditionals in pcretest.c that
2472    had been forgotten.
2473    
2474    2. By using declared but undefined structures, we can avoid using "void"
2475    definitions in pcre.h while keeping the internal definitions of the structures
2476    private.
2477    
2478    3. The distribution is now built using autoconf 2.50 and libtool 1.4. From a
2479    user point of view, this means that both static and shared libraries are built
2480    by default, but this can be individually controlled. More of the work of
2481    handling this static/shared cases is now inside libtool instead of PCRE's make
2482    file.
2483    
2484    4. The pcretest utility is now installed along with pcregrep because it is
2485    useful for users (to test regexs) and by doing this, it automatically gets
2486    relinked by libtool. The documentation has been turned into a man page, so
2487    there are now .1, .txt, and .html versions in /doc.
2488    
2489    5. Upgrades to pcregrep:
2490       (i)   Added long-form option names like gnu grep.
2491       (ii)  Added --help to list all options with an explanatory phrase.
2492       (iii) Added -r, --recursive to recurse into sub-directories.
2493       (iv)  Added -f, --file to read patterns from a file.
2494    
2495    6. pcre_exec() was referring to its "code" argument before testing that
2496    argument for NULL (and giving an error if it was NULL).
2497    
2498    7. Upgraded Makefile.in to allow for compiling in a different directory from
2499    the source directory.
2500    
2501    8. Tiny buglet in pcretest: when pcre_fullinfo() was called to retrieve the
2502    options bits, the pointer it was passed was to an int instead of to an unsigned
2503    long int. This mattered only on 64-bit systems.
2504    
2505    9. Fixed typo (3.4/1) in pcre.h again. Sigh. I had changed pcre.h (which is
2506    generated) instead of pcre.in, which it its source. Also made the same change
2507    in several of the .c files.
2508    
2509    10. A new release of gcc defines printf() as a macro, which broke pcretest
2510    because it had an ifdef in the middle of a string argument for printf(). Fixed
2511    by using separate calls to printf().
2512    
2513    11. Added --enable-newline-is-cr and --enable-newline-is-lf to the configure
2514    script, to force use of CR or LF instead of \n in the source. On non-Unix
2515    systems, the value can be set in config.h.
2516    
2517    12. The limit of 200 on non-capturing parentheses is a _nesting_ limit, not an
2518    absolute limit. Changed the text of the error message to make this clear, and
2519    likewise updated the man page.
2520    
2521    13. The limit of 99 on the number of capturing subpatterns has been removed.
2522    The new limit is 65535, which I hope will not be a "real" limit.
2523    
2524    
2525    Version 3.4 22-Aug-00
2526    ---------------------
2527    
2528    1. Fixed typo in pcre.h: unsigned const char * changed to const unsigned char *.
2529    
2530    2. Diagnose condition (?(0) as an error instead of crashing on matching.
2531    
2532    
2533    Version 3.3 01-Aug-00
2534    ---------------------
2535    
2536    1. If an octal character was given, but the value was greater than \377, it
2537    was not getting masked to the least significant bits, as documented. This could
2538    lead to crashes in some systems.
2539    
2540    2. Perl 5.6 (if not earlier versions) accepts classes like [a-\d] and treats
2541    the hyphen as a literal. PCRE used to give an error; it now behaves like Perl.
2542    
2543    3. Added the functions pcre_free_substring() and pcre_free_substring_list().
2544    These just pass their arguments on to (pcre_free)(), but they are provided
2545    because some uses of PCRE bind it to non-C systems that can call its functions,
2546    but cannot call free() or pcre_free() directly.
2547    
2548    4. Add "make test" as a synonym for "make check". Corrected some comments in
2549    the Makefile.
2550    
2551    5. Add $(DESTDIR)/ in front of all the paths in the "install" target in the
2552    Makefile.
2553    
2554    6. Changed the name of pgrep to pcregrep, because Solaris has introduced a
2555    command called pgrep for grepping around the active processes.
2556    
2557    7. Added the beginnings of support for UTF-8 character strings.
2558    
2559    8. Arranged for the Makefile to pass over the settings of CC, CFLAGS, and
2560    RANLIB to ./ltconfig so that they are used by libtool. I think these are all
2561    the relevant ones. (AR is not passed because ./ltconfig does its own figuring
2562    out for the ar command.)
2563    
2564    
2565    Version 3.2 12-May-00
2566    ---------------------
2567    
2568    This is purely a bug fixing release.
2569    
2570    1. If the pattern /((Z)+|A)*/ was matched agained ZABCDEFG it matched Z instead
2571    of ZA. This was just one example of several cases that could provoke this bug,
2572    which was introduced by change 9 of version 2.00. The code for breaking
2573    infinite loops after an iteration that matches an empty string was't working
2574    correctly.
2575    
2576    2. The pcretest program was not imitating Perl correctly for the pattern /a*/g
2577    when matched against abbab (for example). After matching an empty string, it
2578    wasn't forcing anchoring when setting PCRE_NOTEMPTY for the next attempt; this
2579    caused it to match further down the string than it should.
2580    
2581    3. The code contained an inclusion of sys/types.h. It isn't clear why this
2582    was there because it doesn't seem to be needed, and it causes trouble on some
2583    systems, as it is not a Standard C header. It has been removed.
2584    
2585    4. Made 4 silly changes to the source to avoid stupid compiler warnings that
2586    were reported on the Macintosh. The changes were from
2587    
2588      while ((c = *(++ptr)) != 0 && c != '\n');
2589    to
2590      while ((c = *(++ptr)) != 0 && c != '\n') ;
2591    
2592    Totally extraordinary, but if that's what it takes...
2593    
2594    5. PCRE is being used in one environment where neither memmove() nor bcopy() is
2595    available. Added HAVE_BCOPY and an autoconf test for it; if neither
2596    HAVE_MEMMOVE nor HAVE_BCOPY is set, use a built-in emulation function which
2597    assumes the way PCRE uses memmove() (always moving upwards).
2598    
2599    6. PCRE is being used in one environment where strchr() is not available. There
2600    was only one use in pcre.c, and writing it out to avoid strchr() probably gives
2601    faster code anyway.
2602    
2603    
2604    Version 3.1 09-Feb-00
2605    ---------------------
2606    
2607    The only change in this release is the fixing of some bugs in Makefile.in for
2608    the "install" target:
2609    
2610    (1) It was failing to install pcreposix.h.
2611    
2612    (2) It was overwriting the pcre.3 man page with the pcreposix.3 man page.
2613    
2614    
2615    Version 3.0 01-Feb-00
2616    ---------------------
2617    
2618    1. Add support for the /+ modifier to perltest (to output $` like it does in
2619    pcretest).
2620    
2621    2. Add support for the /g modifier to perltest.
2622    
2623    3. Fix pcretest so that it behaves even more like Perl for /g when the pattern
2624    matches null strings.
2625    
2626    4. Fix perltest so that it doesn't do unwanted things when fed an empty
2627    pattern. Perl treats empty patterns specially - it reuses the most recent
2628    pattern, which is not what we want. Replace // by /(?#)/ in order to avoid this
2629    effect.
2630    
2631    5. The POSIX interface was broken in that it was just handing over the POSIX
2632    captured string vector to pcre_exec(), but (since release 2.00) PCRE has
2633    required a bigger vector, with some working space on the end. This means that
2634    the POSIX wrapper now has to get and free some memory, and copy the results.
2635    
2636    6. Added some simple autoconf support, placing the test data and the
2637    documentation in separate directories, re-organizing some of the
2638    information files, and making it build pcre-config (a GNU standard). Also added
2639    libtool support for building PCRE as a shared library, which is now the
2640    default.
2641    
2642    7. Got rid of the leading zero in the definition of PCRE_MINOR because 08 and
2643    09 are not valid octal constants. Single digits will be used for minor values
2644    less than 10.
2645    
2646    8. Defined REG_EXTENDED and REG_NOSUB as zero in the POSIX header, so that
2647    existing programs that set these in the POSIX interface can use PCRE without
2648    modification.
2649    
2650    9. Added a new function, pcre_fullinfo() with an extensible interface. It can
2651    return all that pcre_info() returns, plus additional data. The pcre_info()
2652    function is retained for compatibility, but is considered to be obsolete.
2653    
2654    10. Added experimental recursion feature (?R) to handle one common case that
2655    Perl 5.6 will be able to do with (?p{...}).
2656    
2657    11. Added support for POSIX character classes like [:alpha:], which Perl is
2658    adopting.
2659    
2660    
2661    Version 2.08 31-Aug-99
2662    ----------------------
2663    
2664    1. When startoffset was not zero and the pattern began with ".*", PCRE was not
2665    trying to match at the startoffset position, but instead was moving forward to
2666    the next newline as if a previous match had failed.
2667    
2668    2. pcretest was not making use of PCRE_NOTEMPTY when repeating for /g and /G,
2669    and could get into a loop if a null string was matched other than at the start
2670    of the subject.
2671    
2672    3. Added definitions of PCRE_MAJOR and PCRE_MINOR to pcre.h so the version can
2673    be distinguished at compile time, and for completeness also added PCRE_DATE.
2674    
2675    5. Added Paul Sokolovsky's minor changes to make it easy to compile a Win32 DLL
2676    in GnuWin32 environments.
2677    
2678    
2679    Version 2.07 29-Jul-99
2680    ----------------------
2681    
2682    1. The documentation is now supplied in plain text form and HTML as well as in
2683    the form of man page sources.
2684    
2685    2. C++ compilers don't like assigning (void *) values to other pointer types.
2686    In particular this affects malloc(). Although there is no problem in Standard
2687    C, I've put in casts to keep C++ compilers happy.
2688    
2689    3. Typo on pcretest.c; a cast of (unsigned char *) in the POSIX regexec() call
2690    should be (const char *).
2691    
2692    4. If NOPOSIX is defined, pcretest.c compiles without POSIX support. This may
2693    be useful for non-Unix systems who don't want to bother with the POSIX stuff.
2694    However, I haven't made this a standard facility. The documentation doesn't
2695    mention it, and the Makefile doesn't support it.
2696    
2697    5. The Makefile now contains an "install" target, with editable destinations at
2698    the top of the file. The pcretest program is not installed.
2699    
2700    6. pgrep -V now gives the PCRE version number and date.
2701    
2702    7. Fixed bug: a zero repetition after a literal string (e.g. /abcde{0}/) was
2703    causing the entire string to be ignored, instead of just the last character.
2704    
2705    8. If a pattern like /"([^\\"]+|\\.)*"/ is applied in the normal way to a
2706    non-matching string, it can take a very, very long time, even for strings of
2707    quite modest length, because of the nested recursion. PCRE now does better in
2708    some of these cases. It does this by remembering the last required literal
2709    character in the pattern, and pre-searching the subject to ensure it is present
2710    before running the real match. In other words, it applies a heuristic to detect
2711    some types of certain failure quickly, and in the above example, if presented
2712    with a string that has no trailing " it gives "no match" very quickly.
2713    
2714    9. A new runtime option PCRE_NOTEMPTY causes null string matches to be ignored;
2715    other alternatives are tried instead.
2716    
2717    
2718    Version 2.06 09-Jun-99
2719    ----------------------
2720    
2721    1. Change pcretest's output for amount of store used to show just the code
2722    space, because the remainder (the data block) varies in size between 32-bit and
2723    64-bit systems.
2724    
2725    2. Added an extra argument to pcre_exec() to supply an offset in the subject to
2726    start matching at. This allows lookbehinds to work when searching for multiple
2727    occurrences in a string.
2728    
2729    3. Added additional options to pcretest for testing multiple occurrences:
2730    
2731       /+   outputs the rest of the string that follows a match
2732       /g   loops for multiple occurrences, using the new startoffset argument
2733       /G   loops for multiple occurrences by passing an incremented pointer
2734    
2735    4. PCRE wasn't doing the "first character" optimization for patterns starting
2736    with \b or \B, though it was doing it for other lookbehind assertions. That is,
2737    it wasn't noticing that a match for a pattern such as /\bxyz/ has to start with
2738    the letter 'x'. On long subject strings, this gives a significant speed-up.
2739    
2740    
2741    Version 2.05 21-Apr-99
2742    ----------------------
2743    
2744    1. Changed the type of magic_number from int to long int so that it works
2745    properly on 16-bit systems.
2746    
2747    2. Fixed a bug which caused patterns starting with .* not to work correctly
2748    when the subject string contained newline characters. PCRE was assuming
2749    anchoring for such patterns in all cases, which is not correct because .* will
2750    not pass a newline unless PCRE_DOTALL is set. It now assumes anchoring only if
2751    DOTALL is set at top level; otherwise it knows that patterns starting with .*
2752    must be retried after every newline in the subject.
2753    
2754    
2755    Version 2.04 18-Feb-99
2756    ----------------------
2757    
2758    1. For parenthesized subpatterns with repeats whose minimum was zero, the
2759    computation of the store needed to hold the pattern was incorrect (too large).
2760    If such patterns were nested a few deep, this could multiply and become a real
2761    problem.
2762    
2763    2. Added /M option to pcretest to show the memory requirement of a specific
2764    pattern. Made -m a synonym of -s (which does this globally) for compatibility.
2765    
2766    3. Subpatterns of the form (regex){n,m} (i.e. limited maximum) were being
2767    compiled in such a way that the backtracking after subsequent failure was
2768    pessimal. Something like (a){0,3} was compiled as (a)?(a)?(a)? instead of
2769    ((a)((a)(a)?)?)? with disastrous performance if the maximum was of any size.
2770    
2771    
2772    Version 2.03 02-Feb-99
2773    ----------------------
2774    
2775    1. Fixed typo and small mistake in man page.
2776    
2777    2. Added 4th condition (GPL supersedes if conflict) and created separate
2778    LICENCE file containing the conditions.
2779    
2780    3. Updated pcretest so that patterns such as /abc\/def/ work like they do in
2781    Perl, that is the internal \ allows the delimiter to be included in the
2782    pattern. Locked out the use of \ as a delimiter. If \ immediately follows
2783    the final delimiter, add \ to the end of the pattern (to test the error).
2784    
2785    4. Added the convenience functions for extracting substrings after a successful
2786    match. Updated pcretest to make it able to test these functions.
2787    
2788    
2789    Version 2.02 14-Jan-99
2790    ----------------------
2791    
2792    1. Initialized the working variables associated with each extraction so that
2793    their saving and restoring doesn't refer to uninitialized store.
2794    
2795    2. Put dummy code into study.c in order to trick the optimizer of the IBM C
2796    compiler for OS/2 into generating correct code. Apparently IBM isn't going to
2797    fix the problem.
2798    
2799    3. Pcretest: the timing code wasn't using LOOPREPEAT for timing execution
2800    calls, and wasn't printing the correct value for compiling calls. Increased the
2801    default value of LOOPREPEAT, and the number of significant figures in the
2802    times.
2803    
2804    4. Changed "/bin/rm" in the Makefile to "-rm" so it works on Windows NT.
2805    
2806    5. Renamed "deftables" as "dftables" to get it down to 8 characters, to avoid
2807    a building problem on Windows NT with a FAT file system.
2808    
2809    
2810    Version 2.01 21-Oct-98
2811    ----------------------
2812    
2813    1. Changed the API for pcre_compile() to allow for the provision of a pointer
2814    to character tables built by pcre_maketables() in the current locale. If NULL
2815    is passed, the default tables are used.
2816    
2817    
2818    Version 2.00 24-Sep-98
2819    ----------------------
2820    
2821    1. Since the (>?) facility is in Perl 5.005, don't require PCRE_EXTRA to enable
2822    it any more.
2823    
2824    2. Allow quantification of (?>) groups, and make it work correctly.
2825    
2826    3. The first character computation wasn't working for (?>) groups.
2827    
2828    4. Correct the implementation of \Z (it is permitted to match on the \n at the
2829    end of the subject) and add 5.005's \z, which really does match only at the
2830    very end of the subject.
2831    
2832    5. Remove the \X "cut" facility; Perl doesn't have it, and (?> is neater.
2833    
2834    6. Remove the ability to specify CASELESS, MULTILINE, DOTALL, and
2835    DOLLAR_END_ONLY at runtime, to make it possible to implement the Perl 5.005
2836    localized options. All options to pcre_study() were also removed.
2837    
2838    7. Add other new features from 5.005:
2839    
2840       $(?<=           positive lookbehind
2841       $(?<!           negative lookbehind
2842       (?imsx-imsx)    added the unsetting capability
2843                       such a setting is global if at outer level; local otherwise
2844       (?imsx-imsx:)   non-capturing groups with option setting
2845       (?(cond)re|re)  conditional pattern matching
2846    
2847       A backreference to itself in a repeated group matches the previous
2848       captured string.
2849    
2850    8. General tidying up of studying (both automatic and via "study")
2851    consequential on the addition of new assertions.
2852    
2853    9. As in 5.005, unlimited repeated groups that could match an empty substring
2854    are no longer faulted at compile time. Instead, the loop is forcibly broken at
2855    runtime if any iteration does actually match an empty substring.
2856    
2857    10. Include the RunTest script in the distribution.
2858    
2859    11. Added tests from the Perl 5.005_02 distribution. This showed up a few
2860    discrepancies, some of which were old and were also with respect to 5.004. They
2861    have now been fixed.
2862    
2863    
2864    Version 1.09 28-Apr-98
2865    ----------------------
2866    
2867    1. A negated single character class followed by a quantifier with a minimum
2868    value of one (e.g.  [^x]{1,6}  ) was not compiled correctly. This could lead to
2869    program crashes, or just wrong answers. This did not apply to negated classes
2870    containing more than one character, or to minima other than one.
2871    
2872    
2873    Version 1.08 27-Mar-98
2874    ----------------------
2875    
2876    1. Add PCRE_UNGREEDY to invert the greediness of quantifiers.
2877    
2878    2. Add (?U) and (?X) to set PCRE_UNGREEDY and PCRE_EXTRA respectively. The
2879    latter must appear before anything that relies on it in the pattern.
2880    
2881    
2882    Version 1.07 16-Feb-98
2883    ----------------------
2884    
2885    1. A pattern such as /((a)*)*/ was not being diagnosed as in error (unlimited
2886    repeat of a potentially empty string).
2887    
2888    
2889    Version 1.06 23-Jan-98
2890    ----------------------
2891    
2892    1. Added Markus Oberhumer's little patches for C++.
2893    
2894    2. Literal strings longer than 255 characters were broken.
2895    
2896    
2897    Version 1.05 23-Dec-97
2898    ----------------------
2899    
2900    1. Negated character classes containing more than one character were failing if
2901    PCRE_CASELESS was set at run time.
2902    
2903    
2904    Version 1.04 19-Dec-97
2905    ----------------------
2906    
2907    1. Corrected the man page, where some "const" qualifiers had been omitted.
2908    
2909    2. Made debugging output print "{0,xxx}" instead of just "{,xxx}" to agree with
2910    input syntax.
2911    
2912    3. Fixed memory leak which occurred when a regex with back references was
2913    matched with an offsets vector that wasn't big enough. The temporary memory
2914    that is used in this case wasn't being freed if the match failed.
2915    
2916    4. Tidied pcretest to ensure it frees memory that it gets.
2917    
2918    5. Temporary memory was being obtained in the case where the passed offsets
2919    vector was exactly big enough.
2920    
2921    6. Corrected definition of offsetof() from change 5 below.
2922    
2923    7. I had screwed up change 6 below and broken the rules for the use of
2924    setjmp(). Now fixed.
2925    
2926    
2927    Version 1.03 18-Dec-97
2928    ----------------------
2929    
2930    1. A erroneous regex with a missing opening parenthesis was correctly
2931    diagnosed, but PCRE attempted to access brastack[-1], which could cause crashes
2932    on some systems.
2933    
2934    2. Replaced offsetof(real_pcre, code) by offsetof(real_pcre, code[0]) because
2935    it was reported that one broken compiler failed on the former because "code" is
2936    also an independent variable.
2937    
2938    3. The erroneous regex a[]b caused an array overrun reference.
2939    
2940    4. A regex ending with a one-character negative class (e.g. /[^k]$/) did not
2941    fail on data ending with that character. (It was going on too far, and checking
2942    the next character, typically a binary zero.) This was specific to the
2943    optimized code for single-character negative classes.
2944    
2945    5. Added a contributed patch from the TIN world which does the following:
2946    
2947      + Add an undef for memmove, in case the the system defines a macro for it.
2948    
2949      + Add a definition of offsetof(), in case there isn't one. (I don't know
2950        the reason behind this - offsetof() is part of the ANSI standard - but
2951        it does no harm).
2952    
2953      + Reduce the ifdef's in pcre.c using macro DPRINTF, thereby eliminating
2954        most of the places where whitespace preceded '#'. I have given up and
2955        allowed the remaining 2 cases to be at the margin.
2956    
2957      + Rename some variables in pcre to eliminate shadowing. This seems very
2958        pedantic, but does no harm, of course.
2959    
2960    6. Moved the call to setjmp() into its own function, to get rid of warnings
2961    from gcc -Wall, and avoided calling it at all unless PCRE_EXTRA is used.
2962    
2963    7. Constructs such as \d{8,} were compiling into the equivalent of
2964    \d{8}\d{0,65527} instead of \d{8}\d* which didn't make much difference to the
2965    outcome, but in this particular case used more store than had been allocated,
2966    which caused the bug to be discovered because it threw up an internal error.
2967    
2968    8. The debugging code in both pcre and pcretest for outputting the compiled
2969    form of a regex was going wrong in the case of back references followed by
2970    curly-bracketed repeats.
2971    
2972    
2973    Version 1.02 12-Dec-97
2974    ----------------------
2975    
2976    1. Typos in pcre.3 and comments in the source fixed.
2977    
2978    2. Applied a contributed patch to get rid of places where it used to remove
2979    'const' from variables, and fixed some signed/unsigned and uninitialized
2980    variable warnings.
2981    
2982    3. Added the "runtest" target to Makefile.
2983    
2984    4. Set default compiler flag to -O2 rather than just -O.
2985    
2986    
2987    Version 1.01 19-Nov-97
2988    ----------------------
2989    
2990    1. PCRE was failing to diagnose unlimited repeat of empty string for patterns
2991    like /([ab]*)*/, that is, for classes with more than one character in them.
2992    
2993    2. Likewise, it wasn't diagnosing patterns with "once-only" subpatterns, such
2994    as /((?>a*))*/ (a PCRE_EXTRA facility).
2995    
2996    
2997    Version 1.00 18-Nov-97
2998    ----------------------
2999    
3000    1. Added compile-time macros to support systems such as SunOS4 which don't have
3001    memmove() or strerror() but have other things that can be used instead.
3002    
3003    2. Arranged that "make clean" removes the executables.
3004    
3005    
3006  Version 0.99 27-Oct-97  Version 0.99 27-Oct-97
3007  ----------------------  ----------------------
3008    

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