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revision 79 by nigel, Sat Feb 24 21:40:52 2007 UTC revision 277 by ph10, Mon Nov 26 17:03:45 2007 UTC
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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
3    
4    Version 7.5 12-Nov-07
5    ---------------------
6    
7    1.  Applied a patch from Craig: "This patch makes it possible to 'ignore'
8        values in parens when parsing an RE using the C++ wrapper."
9    
10    2.  Negative specials like \S did not work in character classes in UTF-8 mode.
11        Characters greater than 255 were excluded from the class instead of being
12        included.
13    
14    3.  The same bug as (2) above applied to negated POSIX classes such as
15        [:^space:].
16    
17    4.  PCRECPP_STATIC was referenced in pcrecpp_internal.h, but nowhere was it
18        defined or documented. It seems to have been a typo for PCRE_STATIC, so
19        I have changed it.
20    
21    5.  The construct (?&) was not diagnosed as a syntax error (it referenced the
22        first named subpattern) and a construct such as (?&a) would reference the
23        first named subpattern whose name started with "a" (in other words, the
24        length check was missing). Both these problems are fixed. "Subpattern name
25        expected" is now given for (?&) (a zero-length name), and this patch also
26        makes it give the same error for \k'' (previously it complained that that
27        was a reference to a non-existent subpattern).
28    
29    6.  The erroneous patterns (?+-a) and (?-+a) give different error messages;
30        this is right because (?- can be followed by option settings as well as by
31        digits. I have, however, made the messages clearer.
32    
33    7.  Patterns such as (?(1)a|b) (a pattern that contains fewer subpatterns
34        than the number used in the conditional) now cause a compile-time error.
35        This is actually not compatible with Perl, which accepts such patterns, but
36        treats the conditional as always being FALSE (as PCRE used to), but it
37        seems to me that giving a diagnostic is better.
38    
39    8.  Change "alphameric" to the more common word "alphanumeric" in comments
40        and messages.
41    
42    9.  Fix two occurrences of "backslash" in comments that should have been
43        "backspace".
44    
45    10. Remove two redundant lines of code that can never be obeyed (their function
46        was moved elsewhere).
47    
48    11. The program that makes PCRE's Unicode character property table had a bug
49        which caused it to generate incorrect table entries for sequences of
50        characters that have the same character type, but are in different scripts.
51        It amalgamated them into a single range, with the script of the first of
52        them. In other words, some characters were in the wrong script. There were
53        thirteen such cases, affecting characters in the following ranges:
54    
55          U+002b0 - U+002c1
56          U+0060c - U+0060d
57          U+0061e - U+00612
58          U+0064b - U+0065e
59          U+0074d - U+0076d
60          U+01800 - U+01805
61          U+01d00 - U+01d77
62          U+01d9b - U+01dbf
63          U+0200b - U+0200f
64          U+030fc - U+030fe
65          U+03260 - U+0327f
66          U+0fb46 - U+0fbb1
67          U+10450 - U+1049d
68    
69    
70    Version 7.4 21-Sep-07
71    ---------------------
72    
73    1.  Change 7.3/28 was implemented for classes by looking at the bitmap. This
74        means that a class such as [\s] counted as "explicit reference to CR or
75        LF". That isn't really right - the whole point of the change was to try to
76        help when there was an actual mention of one of the two characters. So now
77        the change happens only if \r or \n (or a literal CR or LF) character is
78        encountered.
79    
80    2.  The 32-bit options word was also used for 6 internal flags, but the numbers
81        of both had grown to the point where there were only 3 bits left.
82        Fortunately, there was spare space in the data structure, and so I have
83        moved the internal flags into a new 16-bit field to free up more option
84        bits.
85    
86    3.  The appearance of (?J) at the start of a pattern set the DUPNAMES option,
87        but did not set the internal JCHANGED flag - either of these is enough to
88        control the way the "get" function works - but the PCRE_INFO_JCHANGED
89        facility is supposed to tell if (?J) was ever used, so now (?J) at the
90        start sets both bits.
91    
92    4.  Added options (at build time, compile time, exec time) to change \R from
93        matching any Unicode line ending sequence to just matching CR, LF, or CRLF.
94    
95    5.  doc/pcresyntax.html was missing from the distribution.
96    
97    6.  Put back the definition of PCRE_ERROR_NULLWSLIMIT, for backward
98        compatibility, even though it is no longer used.
99    
100    7.  Added macro for snprintf to pcrecpp_unittest.cc and also for strtoll and
101        strtoull to pcrecpp.cc to select the available functions in WIN32 when the
102        windows.h file is present (where different names are used). [This was
103        reversed later after testing - see 16 below.]
104    
105    8.  Changed all #include <config.h> to #include "config.h". There were also
106        some further <pcre.h> cases that I changed to "pcre.h".
107    
108    9.  When pcregrep was used with the --colour option, it missed the line ending
109        sequence off the lines that it output.
110    
111    10. It was pointed out to me that arrays of string pointers cause lots of
112        relocations when a shared library is dynamically loaded. A technique of
113        using a single long string with a table of offsets can drastically reduce
114        these. I have refactored PCRE in four places to do this. The result is
115        dramatic:
116    
117          Originally:                          290
118          After changing UCP table:            187
119          After changing error message table:   43
120          After changing table of "verbs"       36
121          After changing table of Posix names   22
122    
123        Thanks to the folks working on Gregex for glib for this insight.
124    
125    11. --disable-stack-for-recursion caused compiling to fail unless -enable-
126        unicode-properties was also set.
127    
128    12. Updated the tests so that they work when \R is defaulted to ANYCRLF.
129    
130    13. Added checks for ANY and ANYCRLF to pcrecpp.cc where it previously
131        checked only for CRLF.
132    
133    14. Added casts to pcretest.c to avoid compiler warnings.
134    
135    15. Added Craig's patch to various pcrecpp modules to avoid compiler warnings.
136    
137    16. Added Craig's patch to remove the WINDOWS_H tests, that were not working,
138        and instead check for _strtoi64 explicitly, and avoid the use of snprintf()
139        entirely. This removes changes made in 7 above.
140    
141    17. The CMake files have been updated, and there is now more information about
142        building with CMake in the NON-UNIX-USE document.
143    
144    
145    Version 7.3 28-Aug-07
146    ---------------------
147    
148     1. In the rejigging of the build system that eventually resulted in 7.1, the
149        line "#include <pcre.h>" was included in pcre_internal.h. The use of angle
150        brackets there is not right, since it causes compilers to look for an
151        installed pcre.h, not the version that is in the source that is being
152        compiled (which of course may be different). I have changed it back to:
153    
154          #include "pcre.h"
155    
156        I have a vague recollection that the change was concerned with compiling in
157        different directories, but in the new build system, that is taken care of
158        by the VPATH setting the Makefile.
159    
160     2. The pattern .*$ when run in not-DOTALL UTF-8 mode with newline=any failed
161        when the subject happened to end in the byte 0x85 (e.g. if the last
162        character was \x{1ec5}). *Character* 0x85 is one of the "any" newline
163        characters but of course it shouldn't be taken as a newline when it is part
164        of another character. The bug was that, for an unlimited repeat of . in
165        not-DOTALL UTF-8 mode, PCRE was advancing by bytes rather than by
166        characters when looking for a newline.
167    
168     3. A small performance improvement in the DOTALL UTF-8 mode .* case.
169    
170     4. Debugging: adjusted the names of opcodes for different kinds of parentheses
171        in debug output.
172    
173     5. Arrange to use "%I64d" instead of "%lld" and "%I64u" instead of "%llu" for
174        long printing in the pcrecpp unittest when running under MinGW.
175    
176     6. ESC_K was left out of the EBCDIC table.
177    
178     7. Change 7.0/38 introduced a new limit on the number of nested non-capturing
179        parentheses; I made it 1000, which seemed large enough. Unfortunately, the
180        limit also applies to "virtual nesting" when a pattern is recursive, and in
181        this case 1000 isn't so big. I have been able to remove this limit at the
182        expense of backing off one optimization in certain circumstances. Normally,
183        when pcre_exec() would call its internal match() function recursively and
184        immediately return the result unconditionally, it uses a "tail recursion"
185        feature to save stack. However, when a subpattern that can match an empty
186        string has an unlimited repetition quantifier, it no longer makes this
187        optimization. That gives it a stack frame in which to save the data for
188        checking that an empty string has been matched. Previously this was taken
189        from the 1000-entry workspace that had been reserved. So now there is no
190        explicit limit, but more stack is used.
191    
192     8. Applied Daniel's patches to solve problems with the import/export magic
193        syntax that is required for Windows, and which was going wrong for the
194        pcreposix and pcrecpp parts of the library. These were overlooked when this
195        problem was solved for the main library.
196    
197     9. There were some crude static tests to avoid integer overflow when computing
198        the size of patterns that contain repeated groups with explicit upper
199        limits. As the maximum quantifier is 65535, the maximum group length was
200        set at 30,000 so that the product of these two numbers did not overflow a
201        32-bit integer. However, it turns out that people want to use groups that
202        are longer than 30,000 bytes (though not repeat them that many times).
203        Change 7.0/17 (the refactoring of the way the pattern size is computed) has
204        made it possible to implement the integer overflow checks in a much more
205        dynamic way, which I have now done. The artificial limitation on group
206        length has been removed - we now have only the limit on the total length of
207        the compiled pattern, which depends on the LINK_SIZE setting.
208    
209    10. Fixed a bug in the documentation for get/copy named substring when
210        duplicate names are permitted. If none of the named substrings are set, the
211        functions return PCRE_ERROR_NOSUBSTRING (7); the doc said they returned an
212        empty string.
213    
214    11. Because Perl interprets \Q...\E at a high level, and ignores orphan \E
215        instances, patterns such as [\Q\E] or [\E] or even [^\E] cause an error,
216        because the ] is interpreted as the first data character and the
217        terminating ] is not found. PCRE has been made compatible with Perl in this
218        regard. Previously, it interpreted [\Q\E] as an empty class, and [\E] could
219        cause memory overwriting.
220    
221    10. Like Perl, PCRE automatically breaks an unlimited repeat after an empty
222        string has been matched (to stop an infinite loop). It was not recognizing
223        a conditional subpattern that could match an empty string if that
224        subpattern was within another subpattern. For example, it looped when
225        trying to match  (((?(1)X|))*)  but it was OK with  ((?(1)X|)*)  where the
226        condition was not nested. This bug has been fixed.
227    
228    12. A pattern like \X?\d or \P{L}?\d in non-UTF-8 mode could cause a backtrack
229        past the start of the subject in the presence of bytes with the top bit
230        set, for example "\x8aBCD".
231    
232    13. Added Perl 5.10 experimental backtracking controls (*FAIL), (*F), (*PRUNE),
233        (*SKIP), (*THEN), (*COMMIT), and (*ACCEPT).
234    
235    14. Optimized (?!) to (*FAIL).
236    
237    15. Updated the test for a valid UTF-8 string to conform to the later RFC 3629.
238        This restricts code points to be within the range 0 to 0x10FFFF, excluding
239        the "low surrogate" sequence 0xD800 to 0xDFFF. Previously, PCRE allowed the
240        full range 0 to 0x7FFFFFFF, as defined by RFC 2279. Internally, it still
241        does: it's just the validity check that is more restrictive.
242    
243    16. Inserted checks for integer overflows during escape sequence (backslash)
244        processing, and also fixed erroneous offset values for syntax errors during
245        backslash processing.
246    
247    17. Fixed another case of looking too far back in non-UTF-8 mode (cf 12 above)
248        for patterns like [\PPP\x8a]{1,}\x80 with the subject "A\x80".
249    
250    18. An unterminated class in a pattern like (?1)\c[ with a "forward reference"
251        caused an overrun.
252    
253    19. A pattern like (?:[\PPa*]*){8,} which had an "extended class" (one with
254        something other than just ASCII characters) inside a group that had an
255        unlimited repeat caused a loop at compile time (while checking to see
256        whether the group could match an empty string).
257    
258    20. Debugging a pattern containing \p or \P could cause a crash. For example,
259        [\P{Any}] did so. (Error in the code for printing property names.)
260    
261    21. An orphan \E inside a character class could cause a crash.
262    
263    22. A repeated capturing bracket such as (A)? could cause a wild memory
264        reference during compilation.
265    
266    23. There are several functions in pcre_compile() that scan along a compiled
267        expression for various reasons (e.g. to see if it's fixed length for look
268        behind). There were bugs in these functions when a repeated \p or \P was
269        present in the pattern. These operators have additional parameters compared
270        with \d, etc, and these were not being taken into account when moving along
271        the compiled data. Specifically:
272    
273        (a) A item such as \p{Yi}{3} in a lookbehind was not treated as fixed
274            length.
275    
276        (b) An item such as \pL+ within a repeated group could cause crashes or
277            loops.
278    
279        (c) A pattern such as \p{Yi}+(\P{Yi}+)(?1) could give an incorrect
280            "reference to non-existent subpattern" error.
281    
282        (d) A pattern like (\P{Yi}{2}\277)? could loop at compile time.
283    
284    24. A repeated \S or \W in UTF-8 mode could give wrong answers when multibyte
285        characters were involved (for example /\S{2}/8g with "A\x{a3}BC").
286    
287    25. Using pcregrep in multiline, inverted mode (-Mv) caused it to loop.
288    
289    26. Patterns such as [\P{Yi}A] which include \p or \P and just one other
290        character were causing crashes (broken optimization).
291    
292    27. Patterns such as (\P{Yi}*\277)* (group with possible zero repeat containing
293        \p or \P) caused a compile-time loop.
294    
295    28. More problems have arisen in unanchored patterns when CRLF is a valid line
296        break. For example, the unstudied pattern [\r\n]A does not match the string
297        "\r\nA" because change 7.0/46 below moves the current point on by two
298        characters after failing to match at the start. However, the pattern \nA
299        *does* match, because it doesn't start till \n, and if [\r\n]A is studied,
300        the same is true. There doesn't seem any very clean way out of this, but
301        what I have chosen to do makes the common cases work: PCRE now takes note
302        of whether there can be an explicit match for \r or \n anywhere in the
303        pattern, and if so, 7.0/46 no longer applies. As part of this change,
304        there's a new PCRE_INFO_HASCRORLF option for finding out whether a compiled
305        pattern has explicit CR or LF references.
306    
307    29. Added (*CR) etc for changing newline setting at start of pattern.
308    
309    
310    Version 7.2 19-Jun-07
311    ---------------------
312    
313     1. If the fr_FR locale cannot be found for test 3, try the "french" locale,
314        which is apparently normally available under Windows.
315    
316     2. Re-jig the pcregrep tests with different newline settings in an attempt
317        to make them independent of the local environment's newline setting.
318    
319     3. Add code to configure.ac to remove -g from the CFLAGS default settings.
320    
321     4. Some of the "internals" tests were previously cut out when the link size
322        was not 2, because the output contained actual offsets. The recent new
323        "Z" feature of pcretest means that these can be cut out, making the tests
324        usable with all link sizes.
325    
326     5. Implemented Stan Switzer's goto replacement for longjmp() when not using
327        stack recursion. This gives a massive performance boost under BSD, but just
328        a small improvement under Linux. However, it saves one field in the frame
329        in all cases.
330    
331     6. Added more features from the forthcoming Perl 5.10:
332    
333        (a) (?-n) (where n is a string of digits) is a relative subroutine or
334            recursion call. It refers to the nth most recently opened parentheses.
335    
336        (b) (?+n) is also a relative subroutine call; it refers to the nth next
337            to be opened parentheses.
338    
339        (c) Conditions that refer to capturing parentheses can be specified
340            relatively, for example, (?(-2)... or (?(+3)...
341    
342        (d) \K resets the start of the current match so that everything before
343            is not part of it.
344    
345        (e) \k{name} is synonymous with \k<name> and \k'name' (.NET compatible).
346    
347        (f) \g{name} is another synonym - part of Perl 5.10's unification of
348            reference syntax.
349    
350        (g) (?| introduces a group in which the numbering of parentheses in each
351            alternative starts with the same number.
352    
353        (h) \h, \H, \v, and \V match horizontal and vertical whitespace.
354    
355     7. Added two new calls to pcre_fullinfo(): PCRE_INFO_OKPARTIAL and
356        PCRE_INFO_JCHANGED.
357    
358     8. A pattern such as  (.*(.)?)*  caused pcre_exec() to fail by either not
359        terminating or by crashing. Diagnosed by Viktor Griph; it was in the code
360        for detecting groups that can match an empty string.
361    
362     9. A pattern with a very large number of alternatives (more than several
363        hundred) was running out of internal workspace during the pre-compile
364        phase, where pcre_compile() figures out how much memory will be needed. A
365        bit of new cunning has reduced the workspace needed for groups with
366        alternatives. The 1000-alternative test pattern now uses 12 bytes of
367        workspace instead of running out of the 4096 that are available.
368    
369    10. Inserted some missing (unsigned int) casts to get rid of compiler warnings.
370    
371    11. Applied patch from Google to remove an optimization that didn't quite work.
372        The report of the bug said:
373    
374          pcrecpp::RE("a*").FullMatch("aaa") matches, while
375          pcrecpp::RE("a*?").FullMatch("aaa") does not, and
376          pcrecpp::RE("a*?\\z").FullMatch("aaa") does again.
377    
378    12. If \p or \P was used in non-UTF-8 mode on a character greater than 127
379        it matched the wrong number of bytes.
380    
381    
382    Version 7.1 24-Apr-07
383    ---------------------
384    
385     1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
386        that is more "standard", making use of automake and other Autotools. There
387        is some re-arrangement of the files and adjustment of comments consequent
388        on this.
389    
390     2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
391        for recursive directory scanning broke on some systems because the files
392        are not scanned in any specific order and on different systems the order
393        was different. A call to "sort" has been inserted into RunGrepTest for the
394        approprate test as a short-term fix. In the longer term there may be an
395        alternative.
396    
397     3. I had an email from Eric Raymond about problems translating some of PCRE's
398        man pages to HTML (despite the fact that I distribute HTML pages, some
399        people do their own conversions for various reasons). The problems
400        concerned the use of low-level troff macros .br and .in. I have therefore
401        removed all such uses from the man pages (some were redundant, some could
402        be replaced by .nf/.fi pairs). The 132html script that I use to generate
403        HTML has been updated to handle .nf/.fi and to complain if it encounters
404        .br or .in.
405    
406     4. Updated comments in configure.ac that get placed in config.h.in and also
407        arranged for config.h to be included in the distribution, with the name
408        config.h.generic, for the benefit of those who have to compile without
409        Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
410    
411     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
412        Weber: (1) pcre_internal.h was missing some function renames; (2) updated
413        makevp.bat for the current PCRE, using the additional files
414        makevp_c.txt, makevp_l.txt, and pcregexp.pas.
415    
416     6. A Windows user reported a minor discrepancy with test 2, which turned out
417        to be caused by a trailing space on an input line that had got lost in his
418        copy. The trailing space was an accident, so I've just removed it.
419    
420     7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
421        that is needed.
422    
423     8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
424        as "const" (a) because they are and (b) because it helps the PHP
425        maintainers who have recently made a script to detect big data structures
426        in the php code that should be moved to the .rodata section. I remembered
427        to update Builducptable as well, so it won't revert if ucptable.h is ever
428        re-created.
429    
430     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
431        pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
432        order to be able to cut out the UTF-8 tables in the latter when UTF-8
433        support is not required. This saves 1.5-2K of code, which is important in
434        some applications.
435    
436        Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
437        so as not to refer to the tables, even though these functions will never be
438        called when UTF-8 support is disabled. Otherwise there are problems with a
439        shared library.
440    
441    10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
442    
443        (a) It was defining its arguments as char * instead of void *.
444    
445        (b) It was assuming that all moves were upwards in memory; this was true
446            a long time ago when I wrote it, but is no longer the case.
447    
448        The emulated memove() is provided for those environments that have neither
449        memmove() nor bcopy(). I didn't think anyone used it these days, but that
450        is clearly not the case, as these two bugs were recently reported.
451    
452    11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
453        and Detrail to create the HTML documentation, the .txt form of the man
454        pages, and it removes trailing spaces from listed files. It also creates
455        pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
456        case, it wraps all the #defines with #ifndefs. This script should be run
457        before "make dist".
458    
459    12. Fixed two fairly obscure bugs concerned with quantified caseless matching
460        with Unicode property support.
461    
462        (a) For a maximizing quantifier, if the two different cases of the
463            character were of different lengths in their UTF-8 codings (there are
464            some cases like this - I found 11), and the matching function had to
465            back up over a mixture of the two cases, it incorrectly assumed they
466            were both the same length.
467    
468        (b) When PCRE was configured to use the heap rather than the stack for
469            recursion during matching, it was not correctly preserving the data for
470            the other case of a UTF-8 character when checking ahead for a match
471            while processing a minimizing repeat. If the check also involved
472            matching a wide character, but failed, corruption could cause an
473            erroneous result when trying to check for a repeat of the original
474            character.
475    
476    13. Some tidying changes to the testing mechanism:
477    
478        (a) The RunTest script now detects the internal link size and whether there
479            is UTF-8 and UCP support by running ./pcretest -C instead of relying on
480            values substituted by "configure". (The RunGrepTest script already did
481            this for UTF-8.) The configure.ac script no longer substitutes the
482            relevant variables.
483    
484        (b) The debugging options /B and /D in pcretest show the compiled bytecode
485            with length and offset values. This means that the output is different
486            for different internal link sizes. Test 2 is skipped for link sizes
487            other than 2 because of this, bypassing the problem. Unfortunately,
488            there was also a test in test 3 (the locale tests) that used /B and
489            failed for link sizes other than 2. Rather than cut the whole test out,
490            I have added a new /Z option to pcretest that replaces the length and
491            offset values with spaces. This is now used to make test 3 independent
492            of link size. (Test 2 will be tidied up later.)
493    
494    14. If erroroffset was passed as NULL to pcre_compile, it provoked a
495        segmentation fault instead of returning the appropriate error message.
496    
497    15. In multiline mode when the newline sequence was set to "any", the pattern
498        ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
499        This doesn't seem right; it now treats the CRLF combination as the line
500        ending, and so does not match in that case. It's only a pattern such as ^$
501        that would hit this one: something like ^ABC$ would have failed after \r
502        and then tried again after \r\n.
503    
504    16. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
505        in an attempt to make files that differ only in their line terminators
506        compare equal. This works on Linux.
507    
508    17. Under certain error circumstances pcregrep might try to free random memory
509        as it exited. This is now fixed, thanks to valgrind.
510    
511    19. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
512        "abc\r\n\r\n", it found an unwanted second match after the second \r. This
513        was because its rules for how to advance for /g after matching an empty
514        string at the end of a line did not allow for this case. They now check for
515        it specially.
516    
517    20. pcretest is supposed to handle patterns and data of any length, by
518        extending its buffers when necessary. It was getting this wrong when the
519        buffer for a data line had to be extended.
520    
521    21. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or
522        CRLF as a newline sequence.
523    
524    22. Code for handling Unicode properties in pcre_dfa_exec() wasn't being cut
525        out by #ifdef SUPPORT_UCP. This did no harm, as it could never be used, but
526        I have nevertheless tidied it up.
527    
528    23. Added some casts to kill warnings from HP-UX ia64 compiler.
529    
530    24. Added a man page for pcre-config.
531    
532    
533    Version 7.0 19-Dec-06
534    ---------------------
535    
536     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
537        moving to gcc 4.1.1.
538    
539     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
540        sys/time.h, which is documented as needed for this function. It doesn't
541        seem to matter on Linux, but it showed up on some releases of OS X.
542    
543     3. It seems that there are systems where bytes whose values are greater than
544        127 match isprint() in the "C" locale. The "C" locale should be the
545        default when a C program starts up. In most systems, only ASCII printing
546        characters match isprint(). This difference caused the output from pcretest
547        to vary, making some of the tests fail. I have changed pcretest so that:
548    
549        (a) When it is outputting text in the compiled version of a pattern, bytes
550            other than 32-126 are always shown as hex escapes.
551    
552        (b) When it is outputting text that is a matched part of a subject string,
553            it does the same, unless a different locale has been set for the match
554            (using the /L modifier). In this case, it uses isprint() to decide.
555    
556     4. Fixed a major bug that caused incorrect computation of the amount of memory
557        required for a compiled pattern when options that changed within the
558        pattern affected the logic of the preliminary scan that determines the
559        length. The relevant options are -x, and -i in UTF-8 mode. The result was
560        that the computed length was too small. The symptoms of this bug were
561        either the PCRE error "internal error: code overflow" from pcre_compile(),
562        or a glibc crash with a message such as "pcretest: free(): invalid next
563        size (fast)". Examples of patterns that provoked this bug (shown in
564        pcretest format) are:
565    
566          /(?-x: )/x
567          /(?x)(?-x: \s*#\s*)/
568          /((?i)[\x{c0}])/8
569          /(?i:[\x{c0}])/8
570    
571        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
572        is now done differently.
573    
574     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
575        wrapper classes; (b) implement a new function in the C++ scanner that is
576        more efficient than the old way of doing things because it avoids levels of
577        recursion in the regex matching; (c) add a paragraph to the documentation
578        for the FullMatch() function.
579    
580     6. The escape sequence \n was being treated as whatever was defined as
581        "newline". Not only was this contrary to the documentation, which states
582        that \n is character 10 (hex 0A), but it also went horribly wrong when
583        "newline" was defined as CRLF. This has been fixed.
584    
585     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
586        was being set to -1 for the "end of line" case (supposedly a value that no
587        character can have). Though this value is never used (the check for end of
588        line is "zero bytes in current character"), it caused compiler complaints.
589        I've changed it to 0xffffffff.
590    
591     8. In pcre_version.c, the version string was being built by a sequence of
592        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
593        string (as it is for production releases) called a macro with an empty
594        argument. The C standard says the result of this is undefined. The gcc
595        compiler treats it as an empty string (which was what was wanted) but it is
596        reported that Visual C gives an error. The source has been hacked around to
597        avoid this problem.
598    
599     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
600        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
601        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
602        of them did).
603    
604    10. Originally, pcretest opened its input and output without "b"; then I was
605        told that "b" was needed in some environments, so it was added for release
606        5.0 to both the input and output. (It makes no difference on Unix-like
607        systems.) Later I was told that it is wrong for the input on Windows. I've
608        now abstracted the modes into two macros, to make it easier to fiddle with
609        them, and removed "b" from the input mode under Windows.
610    
611    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
612    
613    12. Added -help and --help to pcretest as an official way of being reminded
614        of the options.
615    
616    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
617        and pcrecpp.cc because they annoy compilers at high warning levels.
618    
619    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
620    
621    15. Fixed an occurrence of == in configure.ac that should have been = (shell
622        scripts are not C programs :-) and which was not noticed because it works
623        on Linux.
624    
625    16. pcretest is supposed to handle any length of pattern and data line (as one
626        line or as a continued sequence of lines) by extending its input buffer if
627        necessary. This feature was broken for very long pattern lines, leading to
628        a string of junk being passed to pcre_compile() if the pattern was longer
629        than about 50K.
630    
631    17. I have done a major re-factoring of the way pcre_compile() computes the
632        amount of memory needed for a compiled pattern. Previously, there was code
633        that made a preliminary scan of the pattern in order to do this. That was
634        OK when PCRE was new, but as the facilities have expanded, it has become
635        harder and harder to keep it in step with the real compile phase, and there
636        have been a number of bugs (see for example, 4 above). I have now found a
637        cunning way of running the real compile function in a "fake" mode that
638        enables it to compute how much memory it would need, while actually only
639        ever using a few hundred bytes of working memory and without too many
640        tests of the mode. This should make future maintenance and development
641        easier. A side effect of this work is that the limit of 200 on the nesting
642        depth of parentheses has been removed (though this was never a serious
643        limitation, I suspect). However, there is a downside: pcre_compile() now
644        runs more slowly than before (30% or more, depending on the pattern). I
645        hope this isn't a big issue. There is no effect on runtime performance.
646    
647    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
648        newline (only possible for the last line of a file) and it was a
649        pattern that set a locale (followed by /Lsomething), pcretest crashed.
650    
651    19. Added additional timing features to pcretest. (1) The -tm option now times
652        matching only, not compiling. (2) Both -t and -tm can be followed, as a
653        separate command line item, by a number that specifies the number of
654        repeats to use when timing. The default is 50000; this gives better
655        precision, but takes uncomfortably long for very large patterns.
656    
657    20. Extended pcre_study() to be more clever in cases where a branch of a
658        subpattern has no definite first character. For example, (a*|b*)[cd] would
659        previously give no result from pcre_study(). Now it recognizes that the
660        first character must be a, b, c, or d.
661    
662    21. There was an incorrect error "recursive call could loop indefinitely" if
663        a subpattern (or the entire pattern) that was being tested for matching an
664        empty string contained only one non-empty item after a nested subpattern.
665        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
666        incorrectly, because the \d was being skipped in the check.
667    
668    22. The pcretest program now has a new pattern option /B and a command line
669        option -b, which is equivalent to adding /B to every pattern. This causes
670        it to show the compiled bytecode, without the additional information that
671        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
672        is the same as /B/I).
673    
674    23. A new optimization is now able automatically to treat some sequences such
675        as a*b as a*+b. More specifically, if something simple (such as a character
676        or a simple class like \d) has an unlimited quantifier, and is followed by
677        something that cannot possibly match the quantified thing, the quantifier
678        is automatically "possessified".
679    
680    24. A recursive reference to a subpattern whose number was greater than 39
681        went wrong under certain circumstances in UTF-8 mode. This bug could also
682        have affected the operation of pcre_study().
683    
684    25. Realized that a little bit of performance could be had by replacing
685        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
686    
687    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
688    
689    27. Possessive quantifiers such as a++ were previously implemented by turning
690        them into atomic groups such as ($>a+). Now they have their own opcodes,
691        which improves performance. This includes the automatically created ones
692        from 23 above.
693    
694    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
695        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
696        the first matched character to be a colon. This applied both to named and
697        numbered groups.
698    
699    29. The ucpinternal.h header file was missing its idempotency #ifdef.
700    
701    30. I was sent a "project" file called libpcre.a.dev which I understand makes
702        building PCRE on Windows easier, so I have included it in the distribution.
703    
704    31. There is now a check in pcretest against a ridiculously large number being
705        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
706        loop, the loop is abandoned.
707    
708    32. Forward references to subpatterns in conditions such as (?(2)...) where
709        subpattern 2 is defined later cause pcre_compile() to search forwards in
710        the pattern for the relevant set of parentheses. This search went wrong
711        when there were unescaped parentheses in a character class, parentheses
712        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
713    
714    33. "Subroutine" calls and backreferences were previously restricted to
715        referencing subpatterns earlier in the regex. This restriction has now
716        been removed.
717    
718    34. Added a number of extra features that are going to be in Perl 5.10. On the
719        whole, these are just syntactic alternatives for features that PCRE had
720        previously implemented using the Python syntax or my own invention. The
721        other formats are all retained for compatibility.
722    
723        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
724            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
725            also .NET compatible.
726    
727        (b) A recursion or subroutine call to a named group can now be defined as
728            (?&name) as well as (?P>name).
729    
730        (c) A backreference to a named group can now be defined as \k<name> or
731            \k'name' as well as (?P=name). The new forms, as well as being in Perl
732            5.10, are also .NET compatible.
733    
734        (d) A conditional reference to a named group can now use the syntax
735            (?(<name>) or (?('name') as well as (?(name).
736    
737        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
738            groups (named and numbered) that are never evaluated inline, but can be
739            called as "subroutines" from elsewhere. In effect, the DEFINE condition
740            is always false. There may be only one alternative in such a group.
741    
742        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
743            as the simple (?(R). The condition is true only if the most recent
744            recursion is that of the given number or name. It does not search out
745            through the entire recursion stack.
746    
747        (g) The escape \gN or \g{N} has been added, where N is a positive or
748            negative number, specifying an absolute or relative reference.
749    
750    35. Tidied to get rid of some further signed/unsigned compiler warnings and
751        some "unreachable code" warnings.
752    
753    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
754        things, this adds five new scripts.
755    
756    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
757        There were also incompatibilities regarding the handling of \Q..\E inside
758        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
759        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
760    
761    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
762        matches an empty string, and forcibly breaks the loop. There were bugs in
763        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
764        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
765        separate and independent bugs (that affected different cases) have been
766        fixed.
767    
768    39. Refactored the code to abolish the use of different opcodes for small
769        capturing bracket numbers. This is a tidy that I avoided doing when I
770        removed the limit on the number of capturing brackets for 3.5 back in 2001.
771        The new approach is not only tidier, it makes it possible to reduce the
772        memory needed to fix the previous bug (38).
773    
774    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
775        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
776        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
777        mode.
778    
779    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
780        report.
781    
782    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
783        copy construction and assignment in the C++ wrapper.
784    
785    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
786        couple of bugs that could have given wrong results in the "--newline=crlf"
787        case.
788    
789    44. Added a number of casts and did some reorganization of signed/unsigned int
790        variables following suggestions from Dair Grant. Also renamed the variable
791        "this" as "item" because it is a C++ keyword.
792    
793    45. Arranged for dftables to add
794    
795          #include "pcre_internal.h"
796    
797        to pcre_chartables.c because without it, gcc 4.x may remove the array
798        definition from the final binary if PCRE is built into a static library and
799        dead code stripping is activated.
800    
801    46. For an unanchored pattern, if a match attempt fails at the start of a
802        newline sequence, and the newline setting is CRLF or ANY, and the next two
803        characters are CRLF, advance by two characters instead of one.
804    
805    
806    Version 6.7 04-Jul-06
807    ---------------------
808    
809     1. In order to handle tests when input lines are enormously long, pcretest has
810        been re-factored so that it automatically extends its buffers when
811        necessary. The code is crude, but this _is_ just a test program. The
812        default size has been increased from 32K to 50K.
813    
814     2. The code in pcre_study() was using the value of the re argument before
815        testing it for NULL. (Of course, in any sensible call of the function, it
816        won't be NULL.)
817    
818     3. The memmove() emulation function in pcre_internal.h, which is used on
819        systems that lack both memmove() and bcopy() - that is, hardly ever -
820        was missing a "static" storage class specifier.
821    
822     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
823        containing an extended class (one that cannot be represented by a bitmap
824        because it contains high-valued characters or Unicode property items, e.g.
825        [\pZ]). Almost always one would set UTF-8 mode when processing such a
826        pattern, but PCRE should not loop if you do not (it no longer does).
827        [Detail: two cases were found: (a) a repeated subpattern containing an
828        extended class; (b) a recursive reference to a subpattern that followed a
829        previous extended class. It wasn't skipping over the extended class
830        correctly when UTF-8 mode was not set.]
831    
832     5. A negated single-character class was not being recognized as fixed-length
833        in lookbehind assertions such as (?<=[^f]), leading to an incorrect
834        compile error "lookbehind assertion is not fixed length".
835    
836     6. The RunPerlTest auxiliary script was showing an unexpected difference
837        between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
838        write a Perl script that can interpret lines of an input file either as
839        byte characters or as UTF-8, which is what "perltest" was being required to
840        do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
841        can't do is switch easily at run time between having the "use utf8;" pragma
842        or not. In the end, I fudged it by using the RunPerlTest script to insert
843        "use utf8;" explicitly for the UTF-8 tests.
844    
845     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
846        the end of the subject string, contrary to the documentation and to what
847        Perl does. This was true of both matching functions. Now it matches only at
848        the start of the subject and immediately after *internal* newlines.
849    
850     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
851        a pointer to an int instead of a pointer to an unsigned long int. This
852        caused problems on 64-bit systems.
853    
854     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
855        instance of the 'standard' template library not being so standard".
856    
857    10. There was no check on the number of named subpatterns nor the maximum
858        length of a subpattern name. The product of these values is used to compute
859        the size of the memory block for a compiled pattern. By supplying a very
860        long subpattern name and a large number of named subpatterns, the size
861        computation could be caused to overflow. This is now prevented by limiting
862        the length of names to 32 characters, and the number of named subpatterns
863        to 10,000.
864    
865    11. Subpatterns that are repeated with specific counts have to be replicated in
866        the compiled pattern. The size of memory for this was computed from the
867        length of the subpattern and the repeat count. The latter is limited to
868        65535, but there was no limit on the former, meaning that integer overflow
869        could in principle occur. The compiled length of a repeated subpattern is
870        now limited to 30,000 bytes in order to prevent this.
871    
872    12. Added the optional facility to have named substrings with the same name.
873    
874    13. Added the ability to use a named substring as a condition, using the
875        Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
876        are numbers (not recommended). Forward references are permitted.
877    
878    14. Added forward references in named backreferences (if you see what I mean).
879    
880    15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
881        pattern could run off the end of the subject. For example, the pattern
882        "(?s)(.{1,5})"8 did this with the subject "ab".
883    
884    16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
885        PCRE_CASELESS was set when matching characters that were quantified with ?
886        or *.
887    
888    17. A character class other than a single negated character that had a minimum
889        but no maximum quantifier - for example [ab]{6,} - was not handled
890        correctly by pce_dfa_exec(). It would match only one character.
891    
892    18. A valid (though odd) pattern that looked like a POSIX character
893        class but used an invalid character after [ (for example [[,abc,]]) caused
894        pcre_compile() to give the error "Failed: internal error: code overflow" or
895        in some cases to crash with a glibc free() error. This could even happen if
896        the pattern terminated after [[ but there just happened to be a sequence of
897        letters, a binary zero, and a closing ] in the memory that followed.
898    
899    19. Perl's treatment of octal escapes in the range \400 to \777 has changed
900        over the years. Originally (before any Unicode support), just the bottom 8
901        bits were taken. Thus, for example, \500 really meant \100. Nowadays the
902        output from "man perlunicode" includes this:
903    
904          The regular expression compiler produces polymorphic opcodes.  That
905          is, the pattern adapts to the data and automatically switches to
906          the Unicode character scheme when presented with Unicode data--or
907          instead uses a traditional byte scheme when presented with byte
908          data.
909    
910        Sadly, a wide octal escape does not cause a switch, and in a string with
911        no other multibyte characters, these octal escapes are treated as before.
912        Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
913        /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
914        Unicode string.
915    
916        I have not perpetrated such confusion in PCRE. Up till now, it took just
917        the bottom 8 bits, as in old Perl. I have now made octal escapes with
918        values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
919        translate to the appropriate multibyte character.
920    
921    29. Applied some refactoring to reduce the number of warnings from Microsoft
922        and Borland compilers. This has included removing the fudge introduced
923        seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
924        a warning about an unused variable.
925    
926    21. PCRE has not included VT (character 0x0b) in the set of whitespace
927        characters since release 4.0, because Perl (from release 5.004) does not.
928        [Or at least, is documented not to: some releases seem to be in conflict
929        with the documentation.] However, when a pattern was studied with
930        pcre_study() and all its branches started with \s, PCRE still included VT
931        as a possible starting character. Of course, this did no harm; it just
932        caused an unnecessary match attempt.
933    
934    22. Removed a now-redundant internal flag bit that recorded the fact that case
935        dependency changed within the pattern. This was once needed for "required
936        byte" processing, but is no longer used. This recovers a now-scarce options
937        bit. Also moved the least significant internal flag bit to the most-
938        significant bit of the word, which was not previously used (hangover from
939        the days when it was an int rather than a uint) to free up another bit for
940        the future.
941    
942    23. Added support for CRLF line endings as well as CR and LF. As well as the
943        default being selectable at build time, it can now be changed at runtime
944        via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
945        specify that it is scanning data with non-default line endings.
946    
947    24. Changed the definition of CXXLINK to make it agree with the definition of
948        LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
949    
950    25. Applied Ian Taylor's patches to avoid using another stack frame for tail
951        recursions. This makes a big different to stack usage for some patterns.
952    
953    26. If a subpattern containing a named recursion or subroutine reference such
954        as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
955        the space required for the compiled pattern went wrong and gave too small a
956        value. Depending on the environment, this could lead to "Failed: internal
957        error: code overflow at offset 49" or "glibc detected double free or
958        corruption" errors.
959    
960    27. Applied patches from Google (a) to support the new newline modes and (b) to
961        advance over multibyte UTF-8 characters in GlobalReplace.
962    
963    28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
964        difference for some implementation of PCRE in some Windows version.
965    
966    29. Added some extra testing facilities to pcretest:
967    
968        \q<number>   in a data line sets the "match limit" value
969        \Q<number>   in a data line sets the "match recursion limt" value
970        -S <number>  sets the stack size, where <number> is in megabytes
971    
972        The -S option isn't available for Windows.
973    
974    
975    Version 6.6 06-Feb-06
976    ---------------------
977    
978     1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
979        in pcreposix.h. I have copied the definition from pcre.h.
980    
981     2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
982        because pcre.h is no longer a built file.
983    
984     3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
985        not normally included in the compiled code.
986    
987    
988    Version 6.5 01-Feb-06
989    ---------------------
990    
991     1. When using the partial match feature with pcre_dfa_exec(), it was not
992        anchoring the second and subsequent partial matches at the new starting
993        point. This could lead to incorrect results. For example, with the pattern
994        /1234/, partially matching against "123" and then "a4" gave a match.
995    
996     2. Changes to pcregrep:
997    
998        (a) All non-match returns from pcre_exec() were being treated as failures
999            to match the line. Now, unless the error is PCRE_ERROR_NOMATCH, an
1000            error message is output. Some extra information is given for the
1001            PCRE_ERROR_MATCHLIMIT and PCRE_ERROR_RECURSIONLIMIT errors, which are
1002            probably the only errors that are likely to be caused by users (by
1003            specifying a regex that has nested indefinite repeats, for instance).
1004            If there are more than 20 of these errors, pcregrep is abandoned.
1005    
1006        (b) A binary zero was treated as data while matching, but terminated the
1007            output line if it was written out. This has been fixed: binary zeroes
1008            are now no different to any other data bytes.
1009    
1010        (c) Whichever of the LC_ALL or LC_CTYPE environment variables is set is
1011            used to set a locale for matching. The --locale=xxxx long option has
1012            been added (no short equivalent) to specify a locale explicitly on the
1013            pcregrep command, overriding the environment variables.
1014    
1015        (d) When -B was used with -n, some line numbers in the output were one less
1016            than they should have been.
1017    
1018        (e) Added the -o (--only-matching) option.
1019    
1020        (f) If -A or -C was used with -c (count only), some lines of context were
1021            accidentally printed for the final match.
1022    
1023        (g) Added the -H (--with-filename) option.
1024    
1025        (h) The combination of options -rh failed to suppress file names for files
1026            that were found from directory arguments.
1027    
1028        (i) Added the -D (--devices) and -d (--directories) options.
1029    
1030        (j) Added the -F (--fixed-strings) option.
1031    
1032        (k) Allow "-" to be used as a file name for -f as well as for a data file.
1033    
1034        (l) Added the --colo(u)r option.
1035    
1036        (m) Added Jeffrey Friedl's -S testing option, but within #ifdefs so that it
1037            is not present by default.
1038    
1039     3. A nasty bug was discovered in the handling of recursive patterns, that is,
1040        items such as (?R) or (?1), when the recursion could match a number of
1041        alternatives. If it matched one of the alternatives, but subsequently,
1042        outside the recursion, there was a failure, the code tried to back up into
1043        the recursion. However, because of the way PCRE is implemented, this is not
1044        possible, and the result was an incorrect result from the match.
1045    
1046        In order to prevent this happening, the specification of recursion has
1047        been changed so that all such subpatterns are automatically treated as
1048        atomic groups. Thus, for example, (?R) is treated as if it were (?>(?R)).
1049    
1050     4. I had overlooked the fact that, in some locales, there are characters for
1051        which isalpha() is true but neither isupper() nor islower() are true. In
1052        the fr_FR locale, for instance, the \xAA and \xBA characters (ordmasculine
1053        and ordfeminine) are like this. This affected the treatment of \w and \W
1054        when they appeared in character classes, but not when they appeared outside
1055        a character class. The bit map for "word" characters is now created
1056        separately from the results of isalnum() instead of just taking it from the
1057        upper, lower, and digit maps. (Plus the underscore character, of course.)
1058    
1059     5. The above bug also affected the handling of POSIX character classes such as
1060        [[:alpha:]] and [[:alnum:]]. These do not have their own bit maps in PCRE's
1061        permanent tables. Instead, the bit maps for such a class were previously
1062        created as the appropriate unions of the upper, lower, and digit bitmaps.
1063        Now they are created by subtraction from the [[:word:]] class, which has
1064        its own bitmap.
1065    
1066     6. The [[:blank:]] character class matches horizontal, but not vertical space.
1067        It is created by subtracting the vertical space characters (\x09, \x0a,
1068        \x0b, \x0c) from the [[:space:]] bitmap. Previously, however, the
1069        subtraction was done in the overall bitmap for a character class, meaning
1070        that a class such as [\x0c[:blank:]] was incorrect because \x0c would not
1071        be recognized. This bug has been fixed.
1072    
1073     7. Patches from the folks at Google:
1074    
1075          (a) pcrecpp.cc: "to handle a corner case that may or may not happen in
1076          real life, but is still worth protecting against".
1077    
1078          (b) pcrecpp.cc: "corrects a bug when negative radixes are used with
1079          regular expressions".
1080    
1081          (c) pcre_scanner.cc: avoid use of std::count() because not all systems
1082          have it.
1083    
1084          (d) Split off pcrecpparg.h from pcrecpp.h and had the former built by
1085          "configure" and the latter not, in order to fix a problem somebody had
1086          with compiling the Arg class on HP-UX.
1087    
1088          (e) Improve the error-handling of the C++ wrapper a little bit.
1089    
1090          (f) New tests for checking recursion limiting.
1091    
1092     8. The pcre_memmove() function, which is used only if the environment does not
1093        have a standard memmove() function (and is therefore rarely compiled),
1094        contained two bugs: (a) use of int instead of size_t, and (b) it was not
1095        returning a result (though PCRE never actually uses the result).
1096    
1097     9. In the POSIX regexec() interface, if nmatch is specified as a ridiculously
1098        large number - greater than INT_MAX/(3*sizeof(int)) - REG_ESPACE is
1099        returned instead of calling malloc() with an overflowing number that would
1100        most likely cause subsequent chaos.
1101    
1102    10. The debugging option of pcretest was not showing the NO_AUTO_CAPTURE flag.
1103    
1104    11. The POSIX flag REG_NOSUB is now supported. When a pattern that was compiled
1105        with this option is matched, the nmatch and pmatch options of regexec() are
1106        ignored.
1107    
1108    12. Added REG_UTF8 to the POSIX interface. This is not defined by POSIX, but is
1109        provided in case anyone wants to the the POSIX interface with UTF-8
1110        strings.
1111    
1112    13. Added CXXLDFLAGS to the Makefile parameters to provide settings only on the
1113        C++ linking (needed for some HP-UX environments).
1114    
1115    14. Avoid compiler warnings in get_ucpname() when compiled without UCP support
1116        (unused parameter) and in the pcre_printint() function (omitted "default"
1117        switch label when the default is to do nothing).
1118    
1119    15. Added some code to make it possible, when PCRE is compiled as a C++
1120        library, to replace subject pointers for pcre_exec() with a smart pointer
1121        class, thus making it possible to process discontinuous strings.
1122    
1123    16. The two macros PCRE_EXPORT and PCRE_DATA_SCOPE are confusing, and perform
1124        much the same function. They were added by different people who were trying
1125        to make PCRE easy to compile on non-Unix systems. It has been suggested
1126        that PCRE_EXPORT be abolished now that there is more automatic apparatus
1127        for compiling on Windows systems. I have therefore replaced it with
1128        PCRE_DATA_SCOPE. This is set automatically for Windows; if not set it
1129        defaults to "extern" for C or "extern C" for C++, which works fine on
1130        Unix-like systems. It is now possible to override the value of PCRE_DATA_
1131        SCOPE with something explicit in config.h. In addition:
1132    
1133        (a) pcreposix.h still had just "extern" instead of either of these macros;
1134            I have replaced it with PCRE_DATA_SCOPE.
1135    
1136        (b) Functions such as _pcre_xclass(), which are internal to the library,
1137            but external in the C sense, all had PCRE_EXPORT in their definitions.
1138            This is apparently wrong for the Windows case, so I have removed it.
1139            (It makes no difference on Unix-like systems.)
1140    
1141    17. Added a new limit, MATCH_LIMIT_RECURSION, which limits the depth of nesting
1142        of recursive calls to match(). This is different to MATCH_LIMIT because
1143        that limits the total number of calls to match(), not all of which increase
1144        the depth of recursion. Limiting the recursion depth limits the amount of
1145        stack (or heap if NO_RECURSE is set) that is used. The default can be set
1146        when PCRE is compiled, and changed at run time. A patch from Google adds
1147        this functionality to the C++ interface.
1148    
1149    18. Changes to the handling of Unicode character properties:
1150    
1151        (a) Updated the table to Unicode 4.1.0.
1152    
1153        (b) Recognize characters that are not in the table as "Cn" (undefined).
1154    
1155        (c) I revised the way the table is implemented to a much improved format
1156            which includes recognition of ranges. It now supports the ranges that
1157            are defined in UnicodeData.txt, and it also amalgamates other
1158            characters into ranges. This has reduced the number of entries in the
1159            table from around 16,000 to around 3,000, thus reducing its size
1160            considerably. I realized I did not need to use a tree structure after
1161            all - a binary chop search is just as efficient. Having reduced the
1162            number of entries, I extended their size from 6 bytes to 8 bytes to
1163            allow for more data.
1164    
1165        (d) Added support for Unicode script names via properties such as \p{Han}.
1166    
1167    19. In UTF-8 mode, a backslash followed by a non-Ascii character was not
1168        matching that character.
1169    
1170    20. When matching a repeated Unicode property with a minimum greater than zero,
1171        (for example \pL{2,}), PCRE could look past the end of the subject if it
1172        reached it while seeking the minimum number of characters. This could
1173        happen only if some of the characters were more than one byte long, because
1174        there is a check for at least the minimum number of bytes.
1175    
1176    21. Refactored the implementation of \p and \P so as to be more general, to
1177        allow for more different types of property in future. This has changed the
1178        compiled form incompatibly. Anybody with saved compiled patterns that use
1179        \p or \P will have to recompile them.
1180    
1181    22. Added "Any" and "L&" to the supported property types.
1182    
1183    23. Recognize \x{...} as a code point specifier, even when not in UTF-8 mode,
1184        but give a compile time error if the value is greater than 0xff.
1185    
1186    24. The man pages for pcrepartial, pcreprecompile, and pcre_compile2 were
1187        accidentally not being installed or uninstalled.
1188    
1189    25. The pcre.h file was built from pcre.h.in, but the only changes that were
1190        made were to insert the current release number. This seemed silly, because
1191        it made things harder for people building PCRE on systems that don't run
1192        "configure". I have turned pcre.h into a distributed file, no longer built
1193        by "configure", with the version identification directly included. There is
1194        no longer a pcre.h.in file.
1195    
1196        However, this change necessitated a change to the pcre-config script as
1197        well. It is built from pcre-config.in, and one of the substitutions was the
1198        release number. I have updated configure.ac so that ./configure now finds
1199        the release number by grepping pcre.h.
1200    
1201    26. Added the ability to run the tests under valgrind.
1202    
1203    
1204    Version 6.4 05-Sep-05
1205    ---------------------
1206    
1207     1. Change 6.0/10/(l) to pcregrep introduced a bug that caused separator lines
1208        "--" to be printed when multiple files were scanned, even when none of the
1209        -A, -B, or -C options were used. This is not compatible with Gnu grep, so I
1210        consider it to be a bug, and have restored the previous behaviour.
1211    
1212     2. A couple of code tidies to get rid of compiler warnings.
1213    
1214     3. The pcretest program used to cheat by referring to symbols in the library
1215        whose names begin with _pcre_. These are internal symbols that are not
1216        really supposed to be visible externally, and in some environments it is
1217        possible to suppress them. The cheating is now confined to including
1218        certain files from the library's source, which is a bit cleaner.
1219    
1220     4. Renamed pcre.in as pcre.h.in to go with pcrecpp.h.in; it also makes the
1221        file's purpose clearer.
1222    
1223     5. Reorganized pcre_ucp_findchar().
1224    
1225    
1226    Version 6.3 15-Aug-05
1227    ---------------------
1228    
1229     1. The file libpcre.pc.in did not have general read permission in the tarball.
1230    
1231     2. There were some problems when building without C++ support:
1232    
1233        (a) If C++ support was not built, "make install" and "make test" still
1234            tried to test it.
1235    
1236        (b) There were problems when the value of CXX was explicitly set. Some
1237            changes have been made to try to fix these, and ...
1238    
1239        (c) --disable-cpp can now be used to explicitly disable C++ support.
1240    
1241        (d) The use of @CPP_OBJ@ directly caused a blank line preceded by a
1242            backslash in a target when C++ was disabled. This confuses some
1243            versions of "make", apparently. Using an intermediate variable solves
1244            this. (Same for CPP_LOBJ.)
1245    
1246     3. $(LINK_FOR_BUILD) now includes $(CFLAGS_FOR_BUILD) and $(LINK)
1247        (non-Windows) now includes $(CFLAGS) because these flags are sometimes
1248        necessary on certain architectures.
1249    
1250     4. Added a setting of -export-symbols-regex to the link command to remove
1251        those symbols that are exported in the C sense, but actually are local
1252        within the library, and not documented. Their names all begin with
1253        "_pcre_". This is not a perfect job, because (a) we have to except some
1254        symbols that pcretest ("illegally") uses, and (b) the facility isn't always
1255        available (and never for static libraries). I have made a note to try to
1256        find a way round (a) in the future.
1257    
1258    
1259    Version 6.2 01-Aug-05
1260    ---------------------
1261    
1262     1. There was no test for integer overflow of quantifier values. A construction
1263        such as {1111111111111111} would give undefined results. What is worse, if
1264        a minimum quantifier for a parenthesized subpattern overflowed and became
1265        negative, the calculation of the memory size went wrong. This could have
1266        led to memory overwriting.
1267    
1268     2. Building PCRE using VPATH was broken. Hopefully it is now fixed.
1269    
1270     3. Added "b" to the 2nd argument of fopen() in dftables.c, for non-Unix-like
1271        operating environments where this matters.
1272    
1273     4. Applied Giuseppe Maxia's patch to add additional features for controlling
1274        PCRE options from within the C++ wrapper.
1275    
1276     5. Named capturing subpatterns were not being correctly counted when a pattern
1277        was compiled. This caused two problems: (a) If there were more than 100
1278        such subpatterns, the calculation of the memory needed for the whole
1279        compiled pattern went wrong, leading to an overflow error. (b) Numerical
1280        back references of the form \12, where the number was greater than 9, were
1281        not recognized as back references, even though there were sufficient
1282        previous subpatterns.
1283    
1284     6. Two minor patches to pcrecpp.cc in order to allow it to compile on older
1285        versions of gcc, e.g. 2.95.4.
1286    
1287    
1288  Version 6.1 21-Jun-05  Version 6.1 21-Jun-05
1289  ---------------------  ---------------------
1290    

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