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revision 67 by nigel, Sat Feb 24 21:40:13 2007 UTC revision 276 by ph10, Wed Nov 21 15:39:20 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    
49    Version 7.4 21-Sep-07
50    ---------------------
51    
52    1.  Change 7.3/28 was implemented for classes by looking at the bitmap. This
53        means that a class such as [\s] counted as "explicit reference to CR or
54        LF". That isn't really right - the whole point of the change was to try to
55        help when there was an actual mention of one of the two characters. So now
56        the change happens only if \r or \n (or a literal CR or LF) character is
57        encountered.
58    
59    2.  The 32-bit options word was also used for 6 internal flags, but the numbers
60        of both had grown to the point where there were only 3 bits left.
61        Fortunately, there was spare space in the data structure, and so I have
62        moved the internal flags into a new 16-bit field to free up more option
63        bits.
64    
65    3.  The appearance of (?J) at the start of a pattern set the DUPNAMES option,
66        but did not set the internal JCHANGED flag - either of these is enough to
67        control the way the "get" function works - but the PCRE_INFO_JCHANGED
68        facility is supposed to tell if (?J) was ever used, so now (?J) at the
69        start sets both bits.
70    
71    4.  Added options (at build time, compile time, exec time) to change \R from
72        matching any Unicode line ending sequence to just matching CR, LF, or CRLF.
73    
74    5.  doc/pcresyntax.html was missing from the distribution.
75    
76    6.  Put back the definition of PCRE_ERROR_NULLWSLIMIT, for backward
77        compatibility, even though it is no longer used.
78    
79    7.  Added macro for snprintf to pcrecpp_unittest.cc and also for strtoll and
80        strtoull to pcrecpp.cc to select the available functions in WIN32 when the
81        windows.h file is present (where different names are used). [This was
82        reversed later after testing - see 16 below.]
83    
84    8.  Changed all #include <config.h> to #include "config.h". There were also
85        some further <pcre.h> cases that I changed to "pcre.h".
86    
87    9.  When pcregrep was used with the --colour option, it missed the line ending
88        sequence off the lines that it output.
89    
90    10. It was pointed out to me that arrays of string pointers cause lots of
91        relocations when a shared library is dynamically loaded. A technique of
92        using a single long string with a table of offsets can drastically reduce
93        these. I have refactored PCRE in four places to do this. The result is
94        dramatic:
95    
96          Originally:                          290
97          After changing UCP table:            187
98          After changing error message table:   43
99          After changing table of "verbs"       36
100          After changing table of Posix names   22
101    
102        Thanks to the folks working on Gregex for glib for this insight.
103    
104    11. --disable-stack-for-recursion caused compiling to fail unless -enable-
105        unicode-properties was also set.
106    
107    12. Updated the tests so that they work when \R is defaulted to ANYCRLF.
108    
109    13. Added checks for ANY and ANYCRLF to pcrecpp.cc where it previously
110        checked only for CRLF.
111    
112    14. Added casts to pcretest.c to avoid compiler warnings.
113    
114    15. Added Craig's patch to various pcrecpp modules to avoid compiler warnings.
115    
116    16. Added Craig's patch to remove the WINDOWS_H tests, that were not working,
117        and instead check for _strtoi64 explicitly, and avoid the use of snprintf()
118        entirely. This removes changes made in 7 above.
119    
120    17. The CMake files have been updated, and there is now more information about
121        building with CMake in the NON-UNIX-USE document.
122    
123    
124    Version 7.3 28-Aug-07
125    ---------------------
126    
127     1. In the rejigging of the build system that eventually resulted in 7.1, the
128        line "#include <pcre.h>" was included in pcre_internal.h. The use of angle
129        brackets there is not right, since it causes compilers to look for an
130        installed pcre.h, not the version that is in the source that is being
131        compiled (which of course may be different). I have changed it back to:
132    
133          #include "pcre.h"
134    
135        I have a vague recollection that the change was concerned with compiling in
136        different directories, but in the new build system, that is taken care of
137        by the VPATH setting the Makefile.
138    
139     2. The pattern .*$ when run in not-DOTALL UTF-8 mode with newline=any failed
140        when the subject happened to end in the byte 0x85 (e.g. if the last
141        character was \x{1ec5}). *Character* 0x85 is one of the "any" newline
142        characters but of course it shouldn't be taken as a newline when it is part
143        of another character. The bug was that, for an unlimited repeat of . in
144        not-DOTALL UTF-8 mode, PCRE was advancing by bytes rather than by
145        characters when looking for a newline.
146    
147     3. A small performance improvement in the DOTALL UTF-8 mode .* case.
148    
149     4. Debugging: adjusted the names of opcodes for different kinds of parentheses
150        in debug output.
151    
152     5. Arrange to use "%I64d" instead of "%lld" and "%I64u" instead of "%llu" for
153        long printing in the pcrecpp unittest when running under MinGW.
154    
155     6. ESC_K was left out of the EBCDIC table.
156    
157     7. Change 7.0/38 introduced a new limit on the number of nested non-capturing
158        parentheses; I made it 1000, which seemed large enough. Unfortunately, the
159        limit also applies to "virtual nesting" when a pattern is recursive, and in
160        this case 1000 isn't so big. I have been able to remove this limit at the
161        expense of backing off one optimization in certain circumstances. Normally,
162        when pcre_exec() would call its internal match() function recursively and
163        immediately return the result unconditionally, it uses a "tail recursion"
164        feature to save stack. However, when a subpattern that can match an empty
165        string has an unlimited repetition quantifier, it no longer makes this
166        optimization. That gives it a stack frame in which to save the data for
167        checking that an empty string has been matched. Previously this was taken
168        from the 1000-entry workspace that had been reserved. So now there is no
169        explicit limit, but more stack is used.
170    
171     8. Applied Daniel's patches to solve problems with the import/export magic
172        syntax that is required for Windows, and which was going wrong for the
173        pcreposix and pcrecpp parts of the library. These were overlooked when this
174        problem was solved for the main library.
175    
176     9. There were some crude static tests to avoid integer overflow when computing
177        the size of patterns that contain repeated groups with explicit upper
178        limits. As the maximum quantifier is 65535, the maximum group length was
179        set at 30,000 so that the product of these two numbers did not overflow a
180        32-bit integer. However, it turns out that people want to use groups that
181        are longer than 30,000 bytes (though not repeat them that many times).
182        Change 7.0/17 (the refactoring of the way the pattern size is computed) has
183        made it possible to implement the integer overflow checks in a much more
184        dynamic way, which I have now done. The artificial limitation on group
185        length has been removed - we now have only the limit on the total length of
186        the compiled pattern, which depends on the LINK_SIZE setting.
187    
188    10. Fixed a bug in the documentation for get/copy named substring when
189        duplicate names are permitted. If none of the named substrings are set, the
190        functions return PCRE_ERROR_NOSUBSTRING (7); the doc said they returned an
191        empty string.
192    
193    11. Because Perl interprets \Q...\E at a high level, and ignores orphan \E
194        instances, patterns such as [\Q\E] or [\E] or even [^\E] cause an error,
195        because the ] is interpreted as the first data character and the
196        terminating ] is not found. PCRE has been made compatible with Perl in this
197        regard. Previously, it interpreted [\Q\E] as an empty class, and [\E] could
198        cause memory overwriting.
199    
200    10. Like Perl, PCRE automatically breaks an unlimited repeat after an empty
201        string has been matched (to stop an infinite loop). It was not recognizing
202        a conditional subpattern that could match an empty string if that
203        subpattern was within another subpattern. For example, it looped when
204        trying to match  (((?(1)X|))*)  but it was OK with  ((?(1)X|)*)  where the
205        condition was not nested. This bug has been fixed.
206    
207    12. A pattern like \X?\d or \P{L}?\d in non-UTF-8 mode could cause a backtrack
208        past the start of the subject in the presence of bytes with the top bit
209        set, for example "\x8aBCD".
210    
211    13. Added Perl 5.10 experimental backtracking controls (*FAIL), (*F), (*PRUNE),
212        (*SKIP), (*THEN), (*COMMIT), and (*ACCEPT).
213    
214    14. Optimized (?!) to (*FAIL).
215    
216    15. Updated the test for a valid UTF-8 string to conform to the later RFC 3629.
217        This restricts code points to be within the range 0 to 0x10FFFF, excluding
218        the "low surrogate" sequence 0xD800 to 0xDFFF. Previously, PCRE allowed the
219        full range 0 to 0x7FFFFFFF, as defined by RFC 2279. Internally, it still
220        does: it's just the validity check that is more restrictive.
221    
222    16. Inserted checks for integer overflows during escape sequence (backslash)
223        processing, and also fixed erroneous offset values for syntax errors during
224        backslash processing.
225    
226    17. Fixed another case of looking too far back in non-UTF-8 mode (cf 12 above)
227        for patterns like [\PPP\x8a]{1,}\x80 with the subject "A\x80".
228    
229    18. An unterminated class in a pattern like (?1)\c[ with a "forward reference"
230        caused an overrun.
231    
232    19. A pattern like (?:[\PPa*]*){8,} which had an "extended class" (one with
233        something other than just ASCII characters) inside a group that had an
234        unlimited repeat caused a loop at compile time (while checking to see
235        whether the group could match an empty string).
236    
237    20. Debugging a pattern containing \p or \P could cause a crash. For example,
238        [\P{Any}] did so. (Error in the code for printing property names.)
239    
240    21. An orphan \E inside a character class could cause a crash.
241    
242    22. A repeated capturing bracket such as (A)? could cause a wild memory
243        reference during compilation.
244    
245    23. There are several functions in pcre_compile() that scan along a compiled
246        expression for various reasons (e.g. to see if it's fixed length for look
247        behind). There were bugs in these functions when a repeated \p or \P was
248        present in the pattern. These operators have additional parameters compared
249        with \d, etc, and these were not being taken into account when moving along
250        the compiled data. Specifically:
251    
252        (a) A item such as \p{Yi}{3} in a lookbehind was not treated as fixed
253            length.
254    
255        (b) An item such as \pL+ within a repeated group could cause crashes or
256            loops.
257    
258        (c) A pattern such as \p{Yi}+(\P{Yi}+)(?1) could give an incorrect
259            "reference to non-existent subpattern" error.
260    
261        (d) A pattern like (\P{Yi}{2}\277)? could loop at compile time.
262    
263    24. A repeated \S or \W in UTF-8 mode could give wrong answers when multibyte
264        characters were involved (for example /\S{2}/8g with "A\x{a3}BC").
265    
266    25. Using pcregrep in multiline, inverted mode (-Mv) caused it to loop.
267    
268    26. Patterns such as [\P{Yi}A] which include \p or \P and just one other
269        character were causing crashes (broken optimization).
270    
271    27. Patterns such as (\P{Yi}*\277)* (group with possible zero repeat containing
272        \p or \P) caused a compile-time loop.
273    
274    28. More problems have arisen in unanchored patterns when CRLF is a valid line
275        break. For example, the unstudied pattern [\r\n]A does not match the string
276        "\r\nA" because change 7.0/46 below moves the current point on by two
277        characters after failing to match at the start. However, the pattern \nA
278        *does* match, because it doesn't start till \n, and if [\r\n]A is studied,
279        the same is true. There doesn't seem any very clean way out of this, but
280        what I have chosen to do makes the common cases work: PCRE now takes note
281        of whether there can be an explicit match for \r or \n anywhere in the
282        pattern, and if so, 7.0/46 no longer applies. As part of this change,
283        there's a new PCRE_INFO_HASCRORLF option for finding out whether a compiled
284        pattern has explicit CR or LF references.
285    
286    29. Added (*CR) etc for changing newline setting at start of pattern.
287    
288    
289    Version 7.2 19-Jun-07
290    ---------------------
291    
292     1. If the fr_FR locale cannot be found for test 3, try the "french" locale,
293        which is apparently normally available under Windows.
294    
295     2. Re-jig the pcregrep tests with different newline settings in an attempt
296        to make them independent of the local environment's newline setting.
297    
298     3. Add code to configure.ac to remove -g from the CFLAGS default settings.
299    
300     4. Some of the "internals" tests were previously cut out when the link size
301        was not 2, because the output contained actual offsets. The recent new
302        "Z" feature of pcretest means that these can be cut out, making the tests
303        usable with all link sizes.
304    
305     5. Implemented Stan Switzer's goto replacement for longjmp() when not using
306        stack recursion. This gives a massive performance boost under BSD, but just
307        a small improvement under Linux. However, it saves one field in the frame
308        in all cases.
309    
310     6. Added more features from the forthcoming Perl 5.10:
311    
312        (a) (?-n) (where n is a string of digits) is a relative subroutine or
313            recursion call. It refers to the nth most recently opened parentheses.
314    
315        (b) (?+n) is also a relative subroutine call; it refers to the nth next
316            to be opened parentheses.
317    
318        (c) Conditions that refer to capturing parentheses can be specified
319            relatively, for example, (?(-2)... or (?(+3)...
320    
321        (d) \K resets the start of the current match so that everything before
322            is not part of it.
323    
324        (e) \k{name} is synonymous with \k<name> and \k'name' (.NET compatible).
325    
326        (f) \g{name} is another synonym - part of Perl 5.10's unification of
327            reference syntax.
328    
329        (g) (?| introduces a group in which the numbering of parentheses in each
330            alternative starts with the same number.
331    
332        (h) \h, \H, \v, and \V match horizontal and vertical whitespace.
333    
334     7. Added two new calls to pcre_fullinfo(): PCRE_INFO_OKPARTIAL and
335        PCRE_INFO_JCHANGED.
336    
337     8. A pattern such as  (.*(.)?)*  caused pcre_exec() to fail by either not
338        terminating or by crashing. Diagnosed by Viktor Griph; it was in the code
339        for detecting groups that can match an empty string.
340    
341     9. A pattern with a very large number of alternatives (more than several
342        hundred) was running out of internal workspace during the pre-compile
343        phase, where pcre_compile() figures out how much memory will be needed. A
344        bit of new cunning has reduced the workspace needed for groups with
345        alternatives. The 1000-alternative test pattern now uses 12 bytes of
346        workspace instead of running out of the 4096 that are available.
347    
348    10. Inserted some missing (unsigned int) casts to get rid of compiler warnings.
349    
350    11. Applied patch from Google to remove an optimization that didn't quite work.
351        The report of the bug said:
352    
353          pcrecpp::RE("a*").FullMatch("aaa") matches, while
354          pcrecpp::RE("a*?").FullMatch("aaa") does not, and
355          pcrecpp::RE("a*?\\z").FullMatch("aaa") does again.
356    
357    12. If \p or \P was used in non-UTF-8 mode on a character greater than 127
358        it matched the wrong number of bytes.
359    
360    
361    Version 7.1 24-Apr-07
362    ---------------------
363    
364     1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
365        that is more "standard", making use of automake and other Autotools. There
366        is some re-arrangement of the files and adjustment of comments consequent
367        on this.
368    
369     2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
370        for recursive directory scanning broke on some systems because the files
371        are not scanned in any specific order and on different systems the order
372        was different. A call to "sort" has been inserted into RunGrepTest for the
373        approprate test as a short-term fix. In the longer term there may be an
374        alternative.
375    
376     3. I had an email from Eric Raymond about problems translating some of PCRE's
377        man pages to HTML (despite the fact that I distribute HTML pages, some
378        people do their own conversions for various reasons). The problems
379        concerned the use of low-level troff macros .br and .in. I have therefore
380        removed all such uses from the man pages (some were redundant, some could
381        be replaced by .nf/.fi pairs). The 132html script that I use to generate
382        HTML has been updated to handle .nf/.fi and to complain if it encounters
383        .br or .in.
384    
385     4. Updated comments in configure.ac that get placed in config.h.in and also
386        arranged for config.h to be included in the distribution, with the name
387        config.h.generic, for the benefit of those who have to compile without
388        Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
389    
390     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
391        Weber: (1) pcre_internal.h was missing some function renames; (2) updated
392        makevp.bat for the current PCRE, using the additional files
393        makevp_c.txt, makevp_l.txt, and pcregexp.pas.
394    
395     6. A Windows user reported a minor discrepancy with test 2, which turned out
396        to be caused by a trailing space on an input line that had got lost in his
397        copy. The trailing space was an accident, so I've just removed it.
398    
399     7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
400        that is needed.
401    
402     8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
403        as "const" (a) because they are and (b) because it helps the PHP
404        maintainers who have recently made a script to detect big data structures
405        in the php code that should be moved to the .rodata section. I remembered
406        to update Builducptable as well, so it won't revert if ucptable.h is ever
407        re-created.
408    
409     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
410        pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
411        order to be able to cut out the UTF-8 tables in the latter when UTF-8
412        support is not required. This saves 1.5-2K of code, which is important in
413        some applications.
414    
415        Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
416        so as not to refer to the tables, even though these functions will never be
417        called when UTF-8 support is disabled. Otherwise there are problems with a
418        shared library.
419    
420    10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
421    
422        (a) It was defining its arguments as char * instead of void *.
423    
424        (b) It was assuming that all moves were upwards in memory; this was true
425            a long time ago when I wrote it, but is no longer the case.
426    
427        The emulated memove() is provided for those environments that have neither
428        memmove() nor bcopy(). I didn't think anyone used it these days, but that
429        is clearly not the case, as these two bugs were recently reported.
430    
431    11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
432        and Detrail to create the HTML documentation, the .txt form of the man
433        pages, and it removes trailing spaces from listed files. It also creates
434        pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
435        case, it wraps all the #defines with #ifndefs. This script should be run
436        before "make dist".
437    
438    12. Fixed two fairly obscure bugs concerned with quantified caseless matching
439        with Unicode property support.
440    
441        (a) For a maximizing quantifier, if the two different cases of the
442            character were of different lengths in their UTF-8 codings (there are
443            some cases like this - I found 11), and the matching function had to
444            back up over a mixture of the two cases, it incorrectly assumed they
445            were both the same length.
446    
447        (b) When PCRE was configured to use the heap rather than the stack for
448            recursion during matching, it was not correctly preserving the data for
449            the other case of a UTF-8 character when checking ahead for a match
450            while processing a minimizing repeat. If the check also involved
451            matching a wide character, but failed, corruption could cause an
452            erroneous result when trying to check for a repeat of the original
453            character.
454    
455    13. Some tidying changes to the testing mechanism:
456    
457        (a) The RunTest script now detects the internal link size and whether there
458            is UTF-8 and UCP support by running ./pcretest -C instead of relying on
459            values substituted by "configure". (The RunGrepTest script already did
460            this for UTF-8.) The configure.ac script no longer substitutes the
461            relevant variables.
462    
463        (b) The debugging options /B and /D in pcretest show the compiled bytecode
464            with length and offset values. This means that the output is different
465            for different internal link sizes. Test 2 is skipped for link sizes
466            other than 2 because of this, bypassing the problem. Unfortunately,
467            there was also a test in test 3 (the locale tests) that used /B and
468            failed for link sizes other than 2. Rather than cut the whole test out,
469            I have added a new /Z option to pcretest that replaces the length and
470            offset values with spaces. This is now used to make test 3 independent
471            of link size. (Test 2 will be tidied up later.)
472    
473    14. If erroroffset was passed as NULL to pcre_compile, it provoked a
474        segmentation fault instead of returning the appropriate error message.
475    
476    15. In multiline mode when the newline sequence was set to "any", the pattern
477        ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
478        This doesn't seem right; it now treats the CRLF combination as the line
479        ending, and so does not match in that case. It's only a pattern such as ^$
480        that would hit this one: something like ^ABC$ would have failed after \r
481        and then tried again after \r\n.
482    
483    16. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
484        in an attempt to make files that differ only in their line terminators
485        compare equal. This works on Linux.
486    
487    17. Under certain error circumstances pcregrep might try to free random memory
488        as it exited. This is now fixed, thanks to valgrind.
489    
490    19. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
491        "abc\r\n\r\n", it found an unwanted second match after the second \r. This
492        was because its rules for how to advance for /g after matching an empty
493        string at the end of a line did not allow for this case. They now check for
494        it specially.
495    
496    20. pcretest is supposed to handle patterns and data of any length, by
497        extending its buffers when necessary. It was getting this wrong when the
498        buffer for a data line had to be extended.
499    
500    21. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or
501        CRLF as a newline sequence.
502    
503    22. Code for handling Unicode properties in pcre_dfa_exec() wasn't being cut
504        out by #ifdef SUPPORT_UCP. This did no harm, as it could never be used, but
505        I have nevertheless tidied it up.
506    
507    23. Added some casts to kill warnings from HP-UX ia64 compiler.
508    
509    24. Added a man page for pcre-config.
510    
511    
512    Version 7.0 19-Dec-06
513    ---------------------
514    
515     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
516        moving to gcc 4.1.1.
517    
518     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
519        sys/time.h, which is documented as needed for this function. It doesn't
520        seem to matter on Linux, but it showed up on some releases of OS X.
521    
522     3. It seems that there are systems where bytes whose values are greater than
523        127 match isprint() in the "C" locale. The "C" locale should be the
524        default when a C program starts up. In most systems, only ASCII printing
525        characters match isprint(). This difference caused the output from pcretest
526        to vary, making some of the tests fail. I have changed pcretest so that:
527    
528        (a) When it is outputting text in the compiled version of a pattern, bytes
529            other than 32-126 are always shown as hex escapes.
530    
531        (b) When it is outputting text that is a matched part of a subject string,
532            it does the same, unless a different locale has been set for the match
533            (using the /L modifier). In this case, it uses isprint() to decide.
534    
535     4. Fixed a major bug that caused incorrect computation of the amount of memory
536        required for a compiled pattern when options that changed within the
537        pattern affected the logic of the preliminary scan that determines the
538        length. The relevant options are -x, and -i in UTF-8 mode. The result was
539        that the computed length was too small. The symptoms of this bug were
540        either the PCRE error "internal error: code overflow" from pcre_compile(),
541        or a glibc crash with a message such as "pcretest: free(): invalid next
542        size (fast)". Examples of patterns that provoked this bug (shown in
543        pcretest format) are:
544    
545          /(?-x: )/x
546          /(?x)(?-x: \s*#\s*)/
547          /((?i)[\x{c0}])/8
548          /(?i:[\x{c0}])/8
549    
550        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
551        is now done differently.
552    
553     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
554        wrapper classes; (b) implement a new function in the C++ scanner that is
555        more efficient than the old way of doing things because it avoids levels of
556        recursion in the regex matching; (c) add a paragraph to the documentation
557        for the FullMatch() function.
558    
559     6. The escape sequence \n was being treated as whatever was defined as
560        "newline". Not only was this contrary to the documentation, which states
561        that \n is character 10 (hex 0A), but it also went horribly wrong when
562        "newline" was defined as CRLF. This has been fixed.
563    
564     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
565        was being set to -1 for the "end of line" case (supposedly a value that no
566        character can have). Though this value is never used (the check for end of
567        line is "zero bytes in current character"), it caused compiler complaints.
568        I've changed it to 0xffffffff.
569    
570     8. In pcre_version.c, the version string was being built by a sequence of
571        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
572        string (as it is for production releases) called a macro with an empty
573        argument. The C standard says the result of this is undefined. The gcc
574        compiler treats it as an empty string (which was what was wanted) but it is
575        reported that Visual C gives an error. The source has been hacked around to
576        avoid this problem.
577    
578     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
579        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
580        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
581        of them did).
582    
583    10. Originally, pcretest opened its input and output without "b"; then I was
584        told that "b" was needed in some environments, so it was added for release
585        5.0 to both the input and output. (It makes no difference on Unix-like
586        systems.) Later I was told that it is wrong for the input on Windows. I've
587        now abstracted the modes into two macros, to make it easier to fiddle with
588        them, and removed "b" from the input mode under Windows.
589    
590    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
591    
592    12. Added -help and --help to pcretest as an official way of being reminded
593        of the options.
594    
595    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
596        and pcrecpp.cc because they annoy compilers at high warning levels.
597    
598    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
599    
600    15. Fixed an occurrence of == in configure.ac that should have been = (shell
601        scripts are not C programs :-) and which was not noticed because it works
602        on Linux.
603    
604    16. pcretest is supposed to handle any length of pattern and data line (as one
605        line or as a continued sequence of lines) by extending its input buffer if
606        necessary. This feature was broken for very long pattern lines, leading to
607        a string of junk being passed to pcre_compile() if the pattern was longer
608        than about 50K.
609    
610    17. I have done a major re-factoring of the way pcre_compile() computes the
611        amount of memory needed for a compiled pattern. Previously, there was code
612        that made a preliminary scan of the pattern in order to do this. That was
613        OK when PCRE was new, but as the facilities have expanded, it has become
614        harder and harder to keep it in step with the real compile phase, and there
615        have been a number of bugs (see for example, 4 above). I have now found a
616        cunning way of running the real compile function in a "fake" mode that
617        enables it to compute how much memory it would need, while actually only
618        ever using a few hundred bytes of working memory and without too many
619        tests of the mode. This should make future maintenance and development
620        easier. A side effect of this work is that the limit of 200 on the nesting
621        depth of parentheses has been removed (though this was never a serious
622        limitation, I suspect). However, there is a downside: pcre_compile() now
623        runs more slowly than before (30% or more, depending on the pattern). I
624        hope this isn't a big issue. There is no effect on runtime performance.
625    
626    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
627        newline (only possible for the last line of a file) and it was a
628        pattern that set a locale (followed by /Lsomething), pcretest crashed.
629    
630    19. Added additional timing features to pcretest. (1) The -tm option now times
631        matching only, not compiling. (2) Both -t and -tm can be followed, as a
632        separate command line item, by a number that specifies the number of
633        repeats to use when timing. The default is 50000; this gives better
634        precision, but takes uncomfortably long for very large patterns.
635    
636    20. Extended pcre_study() to be more clever in cases where a branch of a
637        subpattern has no definite first character. For example, (a*|b*)[cd] would
638        previously give no result from pcre_study(). Now it recognizes that the
639        first character must be a, b, c, or d.
640    
641    21. There was an incorrect error "recursive call could loop indefinitely" if
642        a subpattern (or the entire pattern) that was being tested for matching an
643        empty string contained only one non-empty item after a nested subpattern.
644        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
645        incorrectly, because the \d was being skipped in the check.
646    
647    22. The pcretest program now has a new pattern option /B and a command line
648        option -b, which is equivalent to adding /B to every pattern. This causes
649        it to show the compiled bytecode, without the additional information that
650        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
651        is the same as /B/I).
652    
653    23. A new optimization is now able automatically to treat some sequences such
654        as a*b as a*+b. More specifically, if something simple (such as a character
655        or a simple class like \d) has an unlimited quantifier, and is followed by
656        something that cannot possibly match the quantified thing, the quantifier
657        is automatically "possessified".
658    
659    24. A recursive reference to a subpattern whose number was greater than 39
660        went wrong under certain circumstances in UTF-8 mode. This bug could also
661        have affected the operation of pcre_study().
662    
663    25. Realized that a little bit of performance could be had by replacing
664        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
665    
666    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
667    
668    27. Possessive quantifiers such as a++ were previously implemented by turning
669        them into atomic groups such as ($>a+). Now they have their own opcodes,
670        which improves performance. This includes the automatically created ones
671        from 23 above.
672    
673    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
674        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
675        the first matched character to be a colon. This applied both to named and
676        numbered groups.
677    
678    29. The ucpinternal.h header file was missing its idempotency #ifdef.
679    
680    30. I was sent a "project" file called libpcre.a.dev which I understand makes
681        building PCRE on Windows easier, so I have included it in the distribution.
682    
683    31. There is now a check in pcretest against a ridiculously large number being
684        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
685        loop, the loop is abandoned.
686    
687    32. Forward references to subpatterns in conditions such as (?(2)...) where
688        subpattern 2 is defined later cause pcre_compile() to search forwards in
689        the pattern for the relevant set of parentheses. This search went wrong
690        when there were unescaped parentheses in a character class, parentheses
691        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
692    
693    33. "Subroutine" calls and backreferences were previously restricted to
694        referencing subpatterns earlier in the regex. This restriction has now
695        been removed.
696    
697    34. Added a number of extra features that are going to be in Perl 5.10. On the
698        whole, these are just syntactic alternatives for features that PCRE had
699        previously implemented using the Python syntax or my own invention. The
700        other formats are all retained for compatibility.
701    
702        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
703            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
704            also .NET compatible.
705    
706        (b) A recursion or subroutine call to a named group can now be defined as
707            (?&name) as well as (?P>name).
708    
709        (c) A backreference to a named group can now be defined as \k<name> or
710            \k'name' as well as (?P=name). The new forms, as well as being in Perl
711            5.10, are also .NET compatible.
712    
713        (d) A conditional reference to a named group can now use the syntax
714            (?(<name>) or (?('name') as well as (?(name).
715    
716        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
717            groups (named and numbered) that are never evaluated inline, but can be
718            called as "subroutines" from elsewhere. In effect, the DEFINE condition
719            is always false. There may be only one alternative in such a group.
720    
721        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
722            as the simple (?(R). The condition is true only if the most recent
723            recursion is that of the given number or name. It does not search out
724            through the entire recursion stack.
725    
726        (g) The escape \gN or \g{N} has been added, where N is a positive or
727            negative number, specifying an absolute or relative reference.
728    
729    35. Tidied to get rid of some further signed/unsigned compiler warnings and
730        some "unreachable code" warnings.
731    
732    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
733        things, this adds five new scripts.
734    
735    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
736        There were also incompatibilities regarding the handling of \Q..\E inside
737        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
738        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
739    
740    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
741        matches an empty string, and forcibly breaks the loop. There were bugs in
742        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
743        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
744        separate and independent bugs (that affected different cases) have been
745        fixed.
746    
747    39. Refactored the code to abolish the use of different opcodes for small
748        capturing bracket numbers. This is a tidy that I avoided doing when I
749        removed the limit on the number of capturing brackets for 3.5 back in 2001.
750        The new approach is not only tidier, it makes it possible to reduce the
751        memory needed to fix the previous bug (38).
752    
753    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
754        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
755        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
756        mode.
757    
758    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
759        report.
760    
761    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
762        copy construction and assignment in the C++ wrapper.
763    
764    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
765        couple of bugs that could have given wrong results in the "--newline=crlf"
766        case.
767    
768    44. Added a number of casts and did some reorganization of signed/unsigned int
769        variables following suggestions from Dair Grant. Also renamed the variable
770        "this" as "item" because it is a C++ keyword.
771    
772    45. Arranged for dftables to add
773    
774          #include "pcre_internal.h"
775    
776        to pcre_chartables.c because without it, gcc 4.x may remove the array
777        definition from the final binary if PCRE is built into a static library and
778        dead code stripping is activated.
779    
780    46. For an unanchored pattern, if a match attempt fails at the start of a
781        newline sequence, and the newline setting is CRLF or ANY, and the next two
782        characters are CRLF, advance by two characters instead of one.
783    
784    
785    Version 6.7 04-Jul-06
786    ---------------------
787    
788     1. In order to handle tests when input lines are enormously long, pcretest has
789        been re-factored so that it automatically extends its buffers when
790        necessary. The code is crude, but this _is_ just a test program. The
791        default size has been increased from 32K to 50K.
792    
793     2. The code in pcre_study() was using the value of the re argument before
794        testing it for NULL. (Of course, in any sensible call of the function, it
795        won't be NULL.)
796    
797     3. The memmove() emulation function in pcre_internal.h, which is used on
798        systems that lack both memmove() and bcopy() - that is, hardly ever -
799        was missing a "static" storage class specifier.
800    
801     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
802        containing an extended class (one that cannot be represented by a bitmap
803        because it contains high-valued characters or Unicode property items, e.g.
804        [\pZ]). Almost always one would set UTF-8 mode when processing such a
805        pattern, but PCRE should not loop if you do not (it no longer does).
806        [Detail: two cases were found: (a) a repeated subpattern containing an
807        extended class; (b) a recursive reference to a subpattern that followed a
808        previous extended class. It wasn't skipping over the extended class
809        correctly when UTF-8 mode was not set.]
810    
811     5. A negated single-character class was not being recognized as fixed-length
812        in lookbehind assertions such as (?<=[^f]), leading to an incorrect
813        compile error "lookbehind assertion is not fixed length".
814    
815     6. The RunPerlTest auxiliary script was showing an unexpected difference
816        between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
817        write a Perl script that can interpret lines of an input file either as
818        byte characters or as UTF-8, which is what "perltest" was being required to
819        do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
820        can't do is switch easily at run time between having the "use utf8;" pragma
821        or not. In the end, I fudged it by using the RunPerlTest script to insert
822        "use utf8;" explicitly for the UTF-8 tests.
823    
824     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
825        the end of the subject string, contrary to the documentation and to what
826        Perl does. This was true of both matching functions. Now it matches only at
827        the start of the subject and immediately after *internal* newlines.
828    
829     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
830        a pointer to an int instead of a pointer to an unsigned long int. This
831        caused problems on 64-bit systems.
832    
833     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
834        instance of the 'standard' template library not being so standard".
835    
836    10. There was no check on the number of named subpatterns nor the maximum
837        length of a subpattern name. The product of these values is used to compute
838        the size of the memory block for a compiled pattern. By supplying a very
839        long subpattern name and a large number of named subpatterns, the size
840        computation could be caused to overflow. This is now prevented by limiting
841        the length of names to 32 characters, and the number of named subpatterns
842        to 10,000.
843    
844    11. Subpatterns that are repeated with specific counts have to be replicated in
845        the compiled pattern. The size of memory for this was computed from the
846        length of the subpattern and the repeat count. The latter is limited to
847        65535, but there was no limit on the former, meaning that integer overflow
848        could in principle occur. The compiled length of a repeated subpattern is
849        now limited to 30,000 bytes in order to prevent this.
850    
851    12. Added the optional facility to have named substrings with the same name.
852    
853    13. Added the ability to use a named substring as a condition, using the
854        Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
855        are numbers (not recommended). Forward references are permitted.
856    
857    14. Added forward references in named backreferences (if you see what I mean).
858    
859    15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
860        pattern could run off the end of the subject. For example, the pattern
861        "(?s)(.{1,5})"8 did this with the subject "ab".
862    
863    16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
864        PCRE_CASELESS was set when matching characters that were quantified with ?
865        or *.
866    
867    17. A character class other than a single negated character that had a minimum
868        but no maximum quantifier - for example [ab]{6,} - was not handled
869        correctly by pce_dfa_exec(). It would match only one character.
870    
871    18. A valid (though odd) pattern that looked like a POSIX character
872        class but used an invalid character after [ (for example [[,abc,]]) caused
873        pcre_compile() to give the error "Failed: internal error: code overflow" or
874        in some cases to crash with a glibc free() error. This could even happen if
875        the pattern terminated after [[ but there just happened to be a sequence of
876        letters, a binary zero, and a closing ] in the memory that followed.
877    
878    19. Perl's treatment of octal escapes in the range \400 to \777 has changed
879        over the years. Originally (before any Unicode support), just the bottom 8
880        bits were taken. Thus, for example, \500 really meant \100. Nowadays the
881        output from "man perlunicode" includes this:
882    
883          The regular expression compiler produces polymorphic opcodes.  That
884          is, the pattern adapts to the data and automatically switches to
885          the Unicode character scheme when presented with Unicode data--or
886          instead uses a traditional byte scheme when presented with byte
887          data.
888    
889        Sadly, a wide octal escape does not cause a switch, and in a string with
890        no other multibyte characters, these octal escapes are treated as before.
891        Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
892        /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
893        Unicode string.
894    
895        I have not perpetrated such confusion in PCRE. Up till now, it took just
896        the bottom 8 bits, as in old Perl. I have now made octal escapes with
897        values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
898        translate to the appropriate multibyte character.
899    
900    29. Applied some refactoring to reduce the number of warnings from Microsoft
901        and Borland compilers. This has included removing the fudge introduced
902        seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
903        a warning about an unused variable.
904    
905    21. PCRE has not included VT (character 0x0b) in the set of whitespace
906        characters since release 4.0, because Perl (from release 5.004) does not.
907        [Or at least, is documented not to: some releases seem to be in conflict
908        with the documentation.] However, when a pattern was studied with
909        pcre_study() and all its branches started with \s, PCRE still included VT
910        as a possible starting character. Of course, this did no harm; it just
911        caused an unnecessary match attempt.
912    
913    22. Removed a now-redundant internal flag bit that recorded the fact that case
914        dependency changed within the pattern. This was once needed for "required
915        byte" processing, but is no longer used. This recovers a now-scarce options
916        bit. Also moved the least significant internal flag bit to the most-
917        significant bit of the word, which was not previously used (hangover from
918        the days when it was an int rather than a uint) to free up another bit for
919        the future.
920    
921    23. Added support for CRLF line endings as well as CR and LF. As well as the
922        default being selectable at build time, it can now be changed at runtime
923        via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
924        specify that it is scanning data with non-default line endings.
925    
926    24. Changed the definition of CXXLINK to make it agree with the definition of
927        LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
928    
929    25. Applied Ian Taylor's patches to avoid using another stack frame for tail
930        recursions. This makes a big different to stack usage for some patterns.
931    
932    26. If a subpattern containing a named recursion or subroutine reference such
933        as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
934        the space required for the compiled pattern went wrong and gave too small a
935        value. Depending on the environment, this could lead to "Failed: internal
936        error: code overflow at offset 49" or "glibc detected double free or
937        corruption" errors.
938    
939    27. Applied patches from Google (a) to support the new newline modes and (b) to
940        advance over multibyte UTF-8 characters in GlobalReplace.
941    
942    28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
943        difference for some implementation of PCRE in some Windows version.
944    
945    29. Added some extra testing facilities to pcretest:
946    
947        \q<number>   in a data line sets the "match limit" value
948        \Q<number>   in a data line sets the "match recursion limt" value
949        -S <number>  sets the stack size, where <number> is in megabytes
950    
951        The -S option isn't available for Windows.
952    
953    
954    Version 6.6 06-Feb-06
955    ---------------------
956    
957     1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
958        in pcreposix.h. I have copied the definition from pcre.h.
959    
960     2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
961        because pcre.h is no longer a built file.
962    
963     3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
964        not normally included in the compiled code.
965    
966    
967    Version 6.5 01-Feb-06
968    ---------------------
969    
970     1. When using the partial match feature with pcre_dfa_exec(), it was not
971        anchoring the second and subsequent partial matches at the new starting
972        point. This could lead to incorrect results. For example, with the pattern
973        /1234/, partially matching against "123" and then "a4" gave a match.
974    
975     2. Changes to pcregrep:
976    
977        (a) All non-match returns from pcre_exec() were being treated as failures
978            to match the line. Now, unless the error is PCRE_ERROR_NOMATCH, an
979            error message is output. Some extra information is given for the
980            PCRE_ERROR_MATCHLIMIT and PCRE_ERROR_RECURSIONLIMIT errors, which are
981            probably the only errors that are likely to be caused by users (by
982            specifying a regex that has nested indefinite repeats, for instance).
983            If there are more than 20 of these errors, pcregrep is abandoned.
984    
985        (b) A binary zero was treated as data while matching, but terminated the
986            output line if it was written out. This has been fixed: binary zeroes
987            are now no different to any other data bytes.
988    
989        (c) Whichever of the LC_ALL or LC_CTYPE environment variables is set is
990            used to set a locale for matching. The --locale=xxxx long option has
991            been added (no short equivalent) to specify a locale explicitly on the
992            pcregrep command, overriding the environment variables.
993    
994        (d) When -B was used with -n, some line numbers in the output were one less
995            than they should have been.
996    
997        (e) Added the -o (--only-matching) option.
998    
999        (f) If -A or -C was used with -c (count only), some lines of context were
1000            accidentally printed for the final match.
1001    
1002        (g) Added the -H (--with-filename) option.
1003    
1004        (h) The combination of options -rh failed to suppress file names for files
1005            that were found from directory arguments.
1006    
1007        (i) Added the -D (--devices) and -d (--directories) options.
1008    
1009        (j) Added the -F (--fixed-strings) option.
1010    
1011        (k) Allow "-" to be used as a file name for -f as well as for a data file.
1012    
1013        (l) Added the --colo(u)r option.
1014    
1015        (m) Added Jeffrey Friedl's -S testing option, but within #ifdefs so that it
1016            is not present by default.
1017    
1018     3. A nasty bug was discovered in the handling of recursive patterns, that is,
1019        items such as (?R) or (?1), when the recursion could match a number of
1020        alternatives. If it matched one of the alternatives, but subsequently,
1021        outside the recursion, there was a failure, the code tried to back up into
1022        the recursion. However, because of the way PCRE is implemented, this is not
1023        possible, and the result was an incorrect result from the match.
1024    
1025        In order to prevent this happening, the specification of recursion has
1026        been changed so that all such subpatterns are automatically treated as
1027        atomic groups. Thus, for example, (?R) is treated as if it were (?>(?R)).
1028    
1029     4. I had overlooked the fact that, in some locales, there are characters for
1030        which isalpha() is true but neither isupper() nor islower() are true. In
1031        the fr_FR locale, for instance, the \xAA and \xBA characters (ordmasculine
1032        and ordfeminine) are like this. This affected the treatment of \w and \W
1033        when they appeared in character classes, but not when they appeared outside
1034        a character class. The bit map for "word" characters is now created
1035        separately from the results of isalnum() instead of just taking it from the
1036        upper, lower, and digit maps. (Plus the underscore character, of course.)
1037    
1038     5. The above bug also affected the handling of POSIX character classes such as
1039        [[:alpha:]] and [[:alnum:]]. These do not have their own bit maps in PCRE's
1040        permanent tables. Instead, the bit maps for such a class were previously
1041        created as the appropriate unions of the upper, lower, and digit bitmaps.
1042        Now they are created by subtraction from the [[:word:]] class, which has
1043        its own bitmap.
1044    
1045     6. The [[:blank:]] character class matches horizontal, but not vertical space.
1046        It is created by subtracting the vertical space characters (\x09, \x0a,
1047        \x0b, \x0c) from the [[:space:]] bitmap. Previously, however, the
1048        subtraction was done in the overall bitmap for a character class, meaning
1049        that a class such as [\x0c[:blank:]] was incorrect because \x0c would not
1050        be recognized. This bug has been fixed.
1051    
1052     7. Patches from the folks at Google:
1053    
1054          (a) pcrecpp.cc: "to handle a corner case that may or may not happen in
1055          real life, but is still worth protecting against".
1056    
1057          (b) pcrecpp.cc: "corrects a bug when negative radixes are used with
1058          regular expressions".
1059    
1060          (c) pcre_scanner.cc: avoid use of std::count() because not all systems
1061          have it.
1062    
1063          (d) Split off pcrecpparg.h from pcrecpp.h and had the former built by
1064          "configure" and the latter not, in order to fix a problem somebody had
1065          with compiling the Arg class on HP-UX.
1066    
1067          (e) Improve the error-handling of the C++ wrapper a little bit.
1068    
1069          (f) New tests for checking recursion limiting.
1070    
1071     8. The pcre_memmove() function, which is used only if the environment does not
1072        have a standard memmove() function (and is therefore rarely compiled),
1073        contained two bugs: (a) use of int instead of size_t, and (b) it was not
1074        returning a result (though PCRE never actually uses the result).
1075    
1076     9. In the POSIX regexec() interface, if nmatch is specified as a ridiculously
1077        large number - greater than INT_MAX/(3*sizeof(int)) - REG_ESPACE is
1078        returned instead of calling malloc() with an overflowing number that would
1079        most likely cause subsequent chaos.
1080    
1081    10. The debugging option of pcretest was not showing the NO_AUTO_CAPTURE flag.
1082    
1083    11. The POSIX flag REG_NOSUB is now supported. When a pattern that was compiled
1084        with this option is matched, the nmatch and pmatch options of regexec() are
1085        ignored.
1086    
1087    12. Added REG_UTF8 to the POSIX interface. This is not defined by POSIX, but is
1088        provided in case anyone wants to the the POSIX interface with UTF-8
1089        strings.
1090    
1091    13. Added CXXLDFLAGS to the Makefile parameters to provide settings only on the
1092        C++ linking (needed for some HP-UX environments).
1093    
1094    14. Avoid compiler warnings in get_ucpname() when compiled without UCP support
1095        (unused parameter) and in the pcre_printint() function (omitted "default"
1096        switch label when the default is to do nothing).
1097    
1098    15. Added some code to make it possible, when PCRE is compiled as a C++
1099        library, to replace subject pointers for pcre_exec() with a smart pointer
1100        class, thus making it possible to process discontinuous strings.
1101    
1102    16. The two macros PCRE_EXPORT and PCRE_DATA_SCOPE are confusing, and perform
1103        much the same function. They were added by different people who were trying
1104        to make PCRE easy to compile on non-Unix systems. It has been suggested
1105        that PCRE_EXPORT be abolished now that there is more automatic apparatus
1106        for compiling on Windows systems. I have therefore replaced it with
1107        PCRE_DATA_SCOPE. This is set automatically for Windows; if not set it
1108        defaults to "extern" for C or "extern C" for C++, which works fine on
1109        Unix-like systems. It is now possible to override the value of PCRE_DATA_
1110        SCOPE with something explicit in config.h. In addition:
1111    
1112        (a) pcreposix.h still had just "extern" instead of either of these macros;
1113            I have replaced it with PCRE_DATA_SCOPE.
1114    
1115        (b) Functions such as _pcre_xclass(), which are internal to the library,
1116            but external in the C sense, all had PCRE_EXPORT in their definitions.
1117            This is apparently wrong for the Windows case, so I have removed it.
1118            (It makes no difference on Unix-like systems.)
1119    
1120    17. Added a new limit, MATCH_LIMIT_RECURSION, which limits the depth of nesting
1121        of recursive calls to match(). This is different to MATCH_LIMIT because
1122        that limits the total number of calls to match(), not all of which increase
1123        the depth of recursion. Limiting the recursion depth limits the amount of
1124        stack (or heap if NO_RECURSE is set) that is used. The default can be set
1125        when PCRE is compiled, and changed at run time. A patch from Google adds
1126        this functionality to the C++ interface.
1127    
1128    18. Changes to the handling of Unicode character properties:
1129    
1130        (a) Updated the table to Unicode 4.1.0.
1131    
1132        (b) Recognize characters that are not in the table as "Cn" (undefined).
1133    
1134        (c) I revised the way the table is implemented to a much improved format
1135            which includes recognition of ranges. It now supports the ranges that
1136            are defined in UnicodeData.txt, and it also amalgamates other
1137            characters into ranges. This has reduced the number of entries in the
1138            table from around 16,000 to around 3,000, thus reducing its size
1139            considerably. I realized I did not need to use a tree structure after
1140            all - a binary chop search is just as efficient. Having reduced the
1141            number of entries, I extended their size from 6 bytes to 8 bytes to
1142            allow for more data.
1143    
1144        (d) Added support for Unicode script names via properties such as \p{Han}.
1145    
1146    19. In UTF-8 mode, a backslash followed by a non-Ascii character was not
1147        matching that character.
1148    
1149    20. When matching a repeated Unicode property with a minimum greater than zero,
1150        (for example \pL{2,}), PCRE could look past the end of the subject if it
1151        reached it while seeking the minimum number of characters. This could
1152        happen only if some of the characters were more than one byte long, because
1153        there is a check for at least the minimum number of bytes.
1154    
1155    21. Refactored the implementation of \p and \P so as to be more general, to
1156        allow for more different types of property in future. This has changed the
1157        compiled form incompatibly. Anybody with saved compiled patterns that use
1158        \p or \P will have to recompile them.
1159    
1160    22. Added "Any" and "L&" to the supported property types.
1161    
1162    23. Recognize \x{...} as a code point specifier, even when not in UTF-8 mode,
1163        but give a compile time error if the value is greater than 0xff.
1164    
1165    24. The man pages for pcrepartial, pcreprecompile, and pcre_compile2 were
1166        accidentally not being installed or uninstalled.
1167    
1168    25. The pcre.h file was built from pcre.h.in, but the only changes that were
1169        made were to insert the current release number. This seemed silly, because
1170        it made things harder for people building PCRE on systems that don't run
1171        "configure". I have turned pcre.h into a distributed file, no longer built
1172        by "configure", with the version identification directly included. There is
1173        no longer a pcre.h.in file.
1174    
1175        However, this change necessitated a change to the pcre-config script as
1176        well. It is built from pcre-config.in, and one of the substitutions was the
1177        release number. I have updated configure.ac so that ./configure now finds
1178        the release number by grepping pcre.h.
1179    
1180    26. Added the ability to run the tests under valgrind.
1181    
1182    
1183    Version 6.4 05-Sep-05
1184    ---------------------
1185    
1186     1. Change 6.0/10/(l) to pcregrep introduced a bug that caused separator lines
1187        "--" to be printed when multiple files were scanned, even when none of the
1188        -A, -B, or -C options were used. This is not compatible with Gnu grep, so I
1189        consider it to be a bug, and have restored the previous behaviour.
1190    
1191     2. A couple of code tidies to get rid of compiler warnings.
1192    
1193     3. The pcretest program used to cheat by referring to symbols in the library
1194        whose names begin with _pcre_. These are internal symbols that are not
1195        really supposed to be visible externally, and in some environments it is
1196        possible to suppress them. The cheating is now confined to including
1197        certain files from the library's source, which is a bit cleaner.
1198    
1199     4. Renamed pcre.in as pcre.h.in to go with pcrecpp.h.in; it also makes the
1200        file's purpose clearer.
1201    
1202     5. Reorganized pcre_ucp_findchar().
1203    
1204    
1205    Version 6.3 15-Aug-05
1206    ---------------------
1207    
1208     1. The file libpcre.pc.in did not have general read permission in the tarball.
1209    
1210     2. There were some problems when building without C++ support:
1211    
1212        (a) If C++ support was not built, "make install" and "make test" still
1213            tried to test it.
1214    
1215        (b) There were problems when the value of CXX was explicitly set. Some
1216            changes have been made to try to fix these, and ...
1217    
1218        (c) --disable-cpp can now be used to explicitly disable C++ support.
1219    
1220        (d) The use of @CPP_OBJ@ directly caused a blank line preceded by a
1221            backslash in a target when C++ was disabled. This confuses some
1222            versions of "make", apparently. Using an intermediate variable solves
1223            this. (Same for CPP_LOBJ.)
1224    
1225     3. $(LINK_FOR_BUILD) now includes $(CFLAGS_FOR_BUILD) and $(LINK)
1226        (non-Windows) now includes $(CFLAGS) because these flags are sometimes
1227        necessary on certain architectures.
1228    
1229     4. Added a setting of -export-symbols-regex to the link command to remove
1230        those symbols that are exported in the C sense, but actually are local
1231        within the library, and not documented. Their names all begin with
1232        "_pcre_". This is not a perfect job, because (a) we have to except some
1233        symbols that pcretest ("illegally") uses, and (b) the facility isn't always
1234        available (and never for static libraries). I have made a note to try to
1235        find a way round (a) in the future.
1236    
1237    
1238    Version 6.2 01-Aug-05
1239    ---------------------
1240    
1241     1. There was no test for integer overflow of quantifier values. A construction
1242        such as {1111111111111111} would give undefined results. What is worse, if
1243        a minimum quantifier for a parenthesized subpattern overflowed and became
1244        negative, the calculation of the memory size went wrong. This could have
1245        led to memory overwriting.
1246    
1247     2. Building PCRE using VPATH was broken. Hopefully it is now fixed.
1248    
1249     3. Added "b" to the 2nd argument of fopen() in dftables.c, for non-Unix-like
1250        operating environments where this matters.
1251    
1252     4. Applied Giuseppe Maxia's patch to add additional features for controlling
1253        PCRE options from within the C++ wrapper.
1254    
1255     5. Named capturing subpatterns were not being correctly counted when a pattern
1256        was compiled. This caused two problems: (a) If there were more than 100
1257        such subpatterns, the calculation of the memory needed for the whole
1258        compiled pattern went wrong, leading to an overflow error. (b) Numerical
1259        back references of the form \12, where the number was greater than 9, were
1260        not recognized as back references, even though there were sufficient
1261        previous subpatterns.
1262    
1263     6. Two minor patches to pcrecpp.cc in order to allow it to compile on older
1264        versions of gcc, e.g. 2.95.4.
1265    
1266    
1267    Version 6.1 21-Jun-05
1268    ---------------------
1269    
1270     1. There was one reference to the variable "posix" in pcretest.c that was not
1271        surrounded by "#if !defined NOPOSIX".
1272    
1273     2. Make it possible to compile pcretest without DFA support, UTF8 support, or
1274        the cross-check on the old pcre_info() function, for the benefit of the
1275        cut-down version of PCRE that is currently imported into Exim.
1276    
1277     3. A (silly) pattern starting with (?i)(?-i) caused an internal space
1278        allocation error. I've done the easy fix, which wastes 2 bytes for sensible
1279        patterns that start (?i) but I don't think that matters. The use of (?i) is
1280        just an example; this all applies to the other options as well.
1281    
1282     4. Since libtool seems to echo the compile commands it is issuing, the output
1283        from "make" can be reduced a bit by putting "@" in front of each libtool
1284        compile command.
1285    
1286     5. Patch from the folks at Google for configure.in to be a bit more thorough
1287        in checking for a suitable C++ installation before trying to compile the
1288        C++ stuff. This should fix a reported problem when a compiler was present,
1289        but no suitable headers.
1290    
1291     6. The man pages all had just "PCRE" as their title. I have changed them to
1292        be the relevant file name. I have also arranged that these names are
1293        retained in the file doc/pcre.txt, which is a concatenation in text format
1294        of all the man pages except the little individual ones for each function.
1295    
1296     7. The NON-UNIX-USE file had not been updated for the different set of source
1297        files that come with release 6. I also added a few comments about the C++
1298        wrapper.
1299    
1300    
1301    Version 6.0 07-Jun-05
1302    ---------------------
1303    
1304     1. Some minor internal re-organization to help with my DFA experiments.
1305    
1306     2. Some missing #ifdef SUPPORT_UCP conditionals in pcretest and printint that
1307        didn't matter for the library itself when fully configured, but did matter
1308        when compiling without UCP support, or within Exim, where the ucp files are
1309        not imported.
1310    
1311     3. Refactoring of the library code to split up the various functions into
1312        different source modules. The addition of the new DFA matching code (see
1313        below) to a single monolithic source would have made it really too
1314        unwieldy, quite apart from causing all the code to be include in a
1315        statically linked application, when only some functions are used. This is
1316        relevant even without the DFA addition now that patterns can be compiled in
1317        one application and matched in another.
1318    
1319        The downside of splitting up is that there have to be some external
1320        functions and data tables that are used internally in different modules of
1321        the library but which are not part of the API. These have all had their
1322        names changed to start with "_pcre_" so that they are unlikely to clash
1323        with other external names.
1324    
1325     4. Added an alternate matching function, pcre_dfa_exec(), which matches using
1326        a different (DFA) algorithm. Although it is slower than the original
1327        function, it does have some advantages for certain types of matching
1328        problem.
1329    
1330     5. Upgrades to pcretest in order to test the features of pcre_dfa_exec(),
1331        including restarting after a partial match.
1332    
1333     6. A patch for pcregrep that defines INVALID_FILE_ATTRIBUTES if it is not
1334        defined when compiling for Windows was sent to me. I have put it into the
1335        code, though I have no means of testing or verifying it.
1336    
1337     7. Added the pcre_refcount() auxiliary function.
1338    
1339     8. Added the PCRE_FIRSTLINE option. This constrains an unanchored pattern to
1340        match before or at the first newline in the subject string. In pcretest,
1341        the /f option on a pattern can be used to set this.
1342    
1343     9. A repeated \w when used in UTF-8 mode with characters greater than 256
1344        would behave wrongly. This has been present in PCRE since release 4.0.
1345    
1346    10. A number of changes to the pcregrep command:
1347    
1348        (a) Refactored how -x works; insert ^(...)$ instead of setting
1349            PCRE_ANCHORED and checking the length, in preparation for adding
1350            something similar for -w.
1351    
1352        (b) Added the -w (match as a word) option.
1353    
1354        (c) Refactored the way lines are read and buffered so as to have more
1355            than one at a time available.
1356    
1357        (d) Implemented a pcregrep test script.
1358    
1359        (e) Added the -M (multiline match) option. This allows patterns to match
1360            over several lines of the subject. The buffering ensures that at least
1361            8K, or the rest of the document (whichever is the shorter) is available
1362            for matching (and similarly the previous 8K for lookbehind assertions).
1363    
1364        (f) Changed the --help output so that it now says
1365    
1366              -w, --word-regex(p)
1367    
1368            instead of two lines, one with "regex" and the other with "regexp"
1369            because that confused at least one person since the short forms are the
1370            same. (This required a bit of code, as the output is generated
1371            automatically from a table. It wasn't just a text change.)
1372    
1373        (g) -- can be used to terminate pcregrep options if the next thing isn't an
1374            option but starts with a hyphen. Could be a pattern or a path name
1375            starting with a hyphen, for instance.
1376    
1377        (h) "-" can be given as a file name to represent stdin.
1378    
1379        (i) When file names are being printed, "(standard input)" is used for
1380            the standard input, for compatibility with GNU grep. Previously
1381            "<stdin>" was used.
1382    
1383        (j) The option --label=xxx can be used to supply a name to be used for
1384            stdin when file names are being printed. There is no short form.
1385    
1386        (k) Re-factored the options decoding logic because we are going to add
1387            two more options that take data. Such options can now be given in four
1388            different ways, e.g. "-fname", "-f name", "--file=name", "--file name".
1389    
1390        (l) Added the -A, -B, and -C options for requesting that lines of context
1391            around matches be printed.
1392    
1393        (m) Added the -L option to print the names of files that do not contain
1394            any matching lines, that is, the complement of -l.
1395    
1396        (n) The return code is 2 if any file cannot be opened, but pcregrep does
1397            continue to scan other files.
1398    
1399        (o) The -s option was incorrectly implemented. For compatibility with other
1400            greps, it now suppresses the error message for a non-existent or non-
1401            accessible file (but not the return code). There is a new option called
1402            -q that suppresses the output of matching lines, which was what -s was
1403            previously doing.
1404    
1405        (p) Added --include and --exclude options to specify files for inclusion
1406            and exclusion when recursing.
1407    
1408    11. The Makefile was not using the Autoconf-supported LDFLAGS macro properly.
1409        Hopefully, it now does.
1410    
1411    12. Missing cast in pcre_study().
1412    
1413    13. Added an "uninstall" target to the makefile.
1414    
1415    14. Replaced "extern" in the function prototypes in Makefile.in with
1416        "PCRE_DATA_SCOPE", which defaults to 'extern' or 'extern "C"' in the Unix
1417        world, but is set differently for Windows.
1418    
1419    15. Added a second compiling function called pcre_compile2(). The only
1420        difference is that it has an extra argument, which is a pointer to an
1421        integer error code. When there is a compile-time failure, this is set
1422        non-zero, in addition to the error test pointer being set to point to an
1423        error message. The new argument may be NULL if no error number is required
1424        (but then you may as well call pcre_compile(), which is now just a
1425        wrapper). This facility is provided because some applications need a
1426        numeric error indication, but it has also enabled me to tidy up the way
1427        compile-time errors are handled in the POSIX wrapper.
1428    
1429    16. Added VPATH=.libs to the makefile; this should help when building with one
1430        prefix path and installing with another. (Or so I'm told by someone who
1431        knows more about this stuff than I do.)
1432    
1433    17. Added a new option, REG_DOTALL, to the POSIX function regcomp(). This
1434        passes PCRE_DOTALL to the pcre_compile() function, making the "." character
1435        match everything, including newlines. This is not POSIX-compatible, but
1436        somebody wanted the feature. From pcretest it can be activated by using
1437        both the P and the s flags.
1438    
1439    18. AC_PROG_LIBTOOL appeared twice in Makefile.in. Removed one.
1440    
1441    19. libpcre.pc was being incorrectly installed as executable.
1442    
1443    20. A couple of places in pcretest check for end-of-line by looking for '\n';
1444        it now also looks for '\r' so that it will work unmodified on Windows.
1445    
1446    21. Added Google's contributed C++ wrapper to the distribution.
1447    
1448    22. Added some untidy missing memory free() calls in pcretest, to keep
1449        Electric Fence happy when testing.
1450    
1451    
1452    
1453    Version 5.0 13-Sep-04
1454    ---------------------
1455    
1456     1. Internal change: literal characters are no longer packed up into items
1457        containing multiple characters in a single byte-string. Each character
1458        is now matched using a separate opcode. However, there may be more than one
1459        byte in the character in UTF-8 mode.
1460    
1461     2. The pcre_callout_block structure has two new fields: pattern_position and
1462        next_item_length. These contain the offset in the pattern to the next match
1463        item, and its length, respectively.
1464    
1465     3. The PCRE_AUTO_CALLOUT option for pcre_compile() requests the automatic
1466        insertion of callouts before each pattern item. Added the /C option to
1467        pcretest to make use of this.
1468    
1469     4. On the advice of a Windows user, the lines
1470    
1471          #if defined(_WIN32) || defined(WIN32)
1472          _setmode( _fileno( stdout ), 0x8000 );
1473          #endif  /* defined(_WIN32) || defined(WIN32) */
1474    
1475        have been added to the source of pcretest. This apparently does useful
1476        magic in relation to line terminators.
1477    
1478     5. Changed "r" and "w" in the calls to fopen() in pcretest to "rb" and "wb"
1479        for the benefit of those environments where the "b" makes a difference.
1480    
1481     6. The icc compiler has the same options as gcc, but "configure" doesn't seem
1482        to know about it. I have put a hack into configure.in that adds in code
1483        to set GCC=yes if CC=icc. This seems to end up at a point in the
1484        generated configure script that is early enough to affect the setting of
1485        compiler options, which is what is needed, but I have no means of testing
1486        whether it really works. (The user who reported this had patched the
1487        generated configure script, which of course I cannot do.)
1488    
1489        LATER: After change 22 below (new libtool files), the configure script
1490        seems to know about icc (and also ecc). Therefore, I have commented out
1491        this hack in configure.in.
1492    
1493     7. Added support for pkg-config (2 patches were sent in).
1494    
1495     8. Negated POSIX character classes that used a combination of internal tables
1496        were completely broken. These were [[:^alpha:]], [[:^alnum:]], and
1497        [[:^ascii]]. Typically, they would match almost any characters. The other
1498        POSIX classes were not broken in this way.
1499    
1500     9. Matching the pattern "\b.*?" against "ab cd", starting at offset 1, failed
1501        to find the match, as PCRE was deluded into thinking that the match had to
1502        start at the start point or following a newline. The same bug applied to
1503        patterns with negative forward assertions or any backward assertions
1504        preceding ".*" at the start, unless the pattern required a fixed first
1505        character. This was a failing pattern: "(?!.bcd).*". The bug is now fixed.
1506    
1507    10. In UTF-8 mode, when moving forwards in the subject after a failed match
1508        starting at the last subject character, bytes beyond the end of the subject
1509        string were read.
1510    
1511    11. Renamed the variable "class" as "classbits" to make life easier for C++
1512        users. (Previously there was a macro definition, but it apparently wasn't
1513        enough.)
1514    
1515    12. Added the new field "tables" to the extra data so that tables can be passed
1516        in at exec time, or the internal tables can be re-selected. This allows
1517        a compiled regex to be saved and re-used at a later time by a different
1518        program that might have everything at different addresses.
1519    
1520    13. Modified the pcre-config script so that, when run on Solaris, it shows a
1521        -R library as well as a -L library.
1522    
1523    14. The debugging options of pcretest (-d on the command line or D on a
1524        pattern) showed incorrect output for anything following an extended class
1525        that contained multibyte characters and which was followed by a quantifier.
1526    
1527    15. Added optional support for general category Unicode character properties
1528        via the \p, \P, and \X escapes. Unicode property support implies UTF-8
1529        support. It adds about 90K to the size of the library. The meanings of the
1530        inbuilt class escapes such as \d and \s have NOT been changed.
1531    
1532    16. Updated pcredemo.c to include calls to free() to release the memory for the
1533        compiled pattern.
1534    
1535    17. The generated file chartables.c was being created in the source directory
1536        instead of in the building directory. This caused the build to fail if the
1537        source directory was different from the building directory, and was
1538        read-only.
1539    
1540    18. Added some sample Win commands from Mark Tetrode into the NON-UNIX-USE
1541        file. No doubt somebody will tell me if they don't make sense... Also added
1542        Dan Mooney's comments about building on OpenVMS.
1543    
1544    19. Added support for partial matching via the PCRE_PARTIAL option for
1545        pcre_exec() and the \P data escape in pcretest.
1546    
1547    20. Extended pcretest with 3 new pattern features:
1548    
1549        (i)   A pattern option of the form ">rest-of-line" causes pcretest to
1550              write the compiled pattern to the file whose name is "rest-of-line".
1551              This is a straight binary dump of the data, with the saved pointer to
1552              the character tables forced to be NULL. The study data, if any, is
1553              written too. After writing, pcretest reads a new pattern.
1554    
1555        (ii)  If, instead of a pattern, "<rest-of-line" is given, pcretest reads a
1556              compiled pattern from the given file. There must not be any
1557              occurrences of "<" in the file name (pretty unlikely); if there are,
1558              pcretest will instead treat the initial "<" as a pattern delimiter.
1559              After reading in the pattern, pcretest goes on to read data lines as
1560              usual.
1561    
1562        (iii) The F pattern option causes pcretest to flip the bytes in the 32-bit
1563              and 16-bit fields in a compiled pattern, to simulate a pattern that
1564              was compiled on a host of opposite endianness.
1565    
1566    21. The pcre-exec() function can now cope with patterns that were compiled on
1567        hosts of opposite endianness, with this restriction:
1568    
1569          As for any compiled expression that is saved and used later, the tables
1570          pointer field cannot be preserved; the extra_data field in the arguments
1571          to pcre_exec() should be used to pass in a tables address if a value
1572          other than the default internal tables were used at compile time.
1573    
1574    22. Calling pcre_exec() with a negative value of the "ovecsize" parameter is
1575        now diagnosed as an error. Previously, most of the time, a negative number
1576        would have been treated as zero, but if in addition "ovector" was passed as
1577        NULL, a crash could occur.
1578    
1579    23. Updated the files ltmain.sh, config.sub, config.guess, and aclocal.m4 with
1580        new versions from the libtool 1.5 distribution (the last one is a copy of
1581        a file called libtool.m4). This seems to have fixed the need to patch
1582        "configure" to support Darwin 1.3 (which I used to do). However, I still
1583        had to patch ltmain.sh to ensure that ${SED} is set (it isn't on my
1584        workstation).
1585    
1586    24. Changed the PCRE licence to be the more standard "BSD" licence.
1587    
1588    
1589    Version 4.5 01-Dec-03
1590    ---------------------
1591    
1592     1. There has been some re-arrangement of the code for the match() function so
1593        that it can be compiled in a version that does not call itself recursively.
1594        Instead, it keeps those local variables that need separate instances for
1595        each "recursion" in a frame on the heap, and gets/frees frames whenever it
1596        needs to "recurse". Keeping track of where control must go is done by means
1597        of setjmp/longjmp. The whole thing is implemented by a set of macros that
1598        hide most of the details from the main code, and operates only if
1599        NO_RECURSE is defined while compiling pcre.c. If PCRE is built using the
1600        "configure" mechanism, "--disable-stack-for-recursion" turns on this way of
1601        operating.
1602    
1603        To make it easier for callers to provide specially tailored get/free
1604        functions for this usage, two new functions, pcre_stack_malloc, and
1605        pcre_stack_free, are used. They are always called in strict stacking order,
1606        and the size of block requested is always the same.
1607    
1608        The PCRE_CONFIG_STACKRECURSE info parameter can be used to find out whether
1609        PCRE has been compiled to use the stack or the heap for recursion. The
1610        -C option of pcretest uses this to show which version is compiled.
1611    
1612        A new data escape \S, is added to pcretest; it causes the amounts of store
1613        obtained and freed by both kinds of malloc/free at match time to be added
1614        to the output.
1615    
1616     2. Changed the locale test to use "fr_FR" instead of "fr" because that's
1617        what's available on my current Linux desktop machine.
1618    
1619     3. When matching a UTF-8 string, the test for a valid string at the start has
1620        been extended. If start_offset is not zero, PCRE now checks that it points
1621        to a byte that is the start of a UTF-8 character. If not, it returns
1622        PCRE_ERROR_BADUTF8_OFFSET (-11). Note: the whole string is still checked;
1623        this is necessary because there may be backward assertions in the pattern.
1624        When matching the same subject several times, it may save resources to use
1625        PCRE_NO_UTF8_CHECK on all but the first call if the string is long.
1626    
1627     4. The code for checking the validity of UTF-8 strings has been tightened so
1628        that it rejects (a) strings containing 0xfe or 0xff bytes and (b) strings
1629        containing "overlong sequences".
1630    
1631     5. Fixed a bug (appearing twice) that I could not find any way of exploiting!
1632        I had written "if ((digitab[*p++] && chtab_digit) == 0)" where the "&&"
1633        should have been "&", but it just so happened that all the cases this let
1634        through by mistake were picked up later in the function.
1635    
1636     6. I had used a variable called "isblank" - this is a C99 function, causing
1637        some compilers to warn. To avoid this, I renamed it (as "blankclass").
1638    
1639     7. Cosmetic: (a) only output another newline at the end of pcretest if it is
1640        prompting; (b) run "./pcretest /dev/null" at the start of the test script
1641        so the version is shown; (c) stop "make test" echoing "./RunTest".
1642    
1643     8. Added patches from David Burgess to enable PCRE to run on EBCDIC systems.
1644    
1645     9. The prototype for memmove() for systems that don't have it was using
1646        size_t, but the inclusion of the header that defines size_t was later. I've
1647        moved the #includes for the C headers earlier to avoid this.
1648    
1649    10. Added some adjustments to the code to make it easier to compiler on certain
1650        special systems:
1651    
1652          (a) Some "const" qualifiers were missing.
1653          (b) Added the macro EXPORT before all exported functions; by default this
1654              is defined to be empty.
1655          (c) Changed the dftables auxiliary program (that builds chartables.c) so
1656              that it reads its output file name as an argument instead of writing
1657              to the standard output and assuming this can be redirected.
1658    
1659    11. In UTF-8 mode, if a recursive reference (e.g. (?1)) followed a character
1660        class containing characters with values greater than 255, PCRE compilation
1661        went into a loop.
1662    
1663    12. A recursive reference to a subpattern that was within another subpattern
1664        that had a minimum quantifier of zero caused PCRE to crash. For example,
1665        (x(y(?2))z)? provoked this bug with a subject that got as far as the
1666        recursion. If the recursively-called subpattern itself had a zero repeat,
1667        that was OK.
1668    
1669    13. In pcretest, the buffer for reading a data line was set at 30K, but the
1670        buffer into which it was copied (for escape processing) was still set at
1671        1024, so long lines caused crashes.
1672    
1673    14. A pattern such as /[ab]{1,3}+/ failed to compile, giving the error
1674        "internal error: code overflow...". This applied to any character class
1675        that was followed by a possessive quantifier.
1676    
1677    15. Modified the Makefile to add libpcre.la as a prerequisite for
1678        libpcreposix.la because I was told this is needed for a parallel build to
1679        work.
1680    
1681    16. If a pattern that contained .* following optional items at the start was
1682        studied, the wrong optimizing data was generated, leading to matching
1683        errors. For example, studying /[ab]*.*c/ concluded, erroneously, that any
1684        matching string must start with a or b or c. The correct conclusion for
1685        this pattern is that a match can start with any character.
1686    
1687    
1688    Version 4.4 13-Aug-03
1689    ---------------------
1690    
1691     1. In UTF-8 mode, a character class containing characters with values between
1692        127 and 255 was not handled correctly if the compiled pattern was studied.
1693        In fixing this, I have also improved the studying algorithm for such
1694        classes (slightly).
1695    
1696     2. Three internal functions had redundant arguments passed to them. Removal
1697        might give a very teeny performance improvement.
1698    
1699     3. Documentation bug: the value of the capture_top field in a callout is *one
1700        more than* the number of the hightest numbered captured substring.
1701    
1702     4. The Makefile linked pcretest and pcregrep with -lpcre, which could result
1703        in incorrectly linking with a previously installed version. They now link
1704        explicitly with libpcre.la.
1705    
1706     5. configure.in no longer needs to recognize Cygwin specially.
1707    
1708     6. A problem in pcre.in for Windows platforms is fixed.
1709    
1710     7. If a pattern was successfully studied, and the -d (or /D) flag was given to
1711        pcretest, it used to include the size of the study block as part of its
1712        output. Unfortunately, the structure contains a field that has a different
1713        size on different hardware architectures. This meant that the tests that
1714        showed this size failed. As the block is currently always of a fixed size,
1715        this information isn't actually particularly useful in pcretest output, so
1716        I have just removed it.
1717    
1718     8. Three pre-processor statements accidentally did not start in column 1.
1719        Sadly, there are *still* compilers around that complain, even though
1720        standard C has not required this for well over a decade. Sigh.
1721    
1722     9. In pcretest, the code for checking callouts passed small integers in the
1723        callout_data field, which is a void * field. However, some picky compilers
1724        complained about the casts involved for this on 64-bit systems. Now
1725        pcretest passes the address of the small integer instead, which should get
1726        rid of the warnings.
1727    
1728    10. By default, when in UTF-8 mode, PCRE now checks for valid UTF-8 strings at
1729        both compile and run time, and gives an error if an invalid UTF-8 sequence
1730        is found. There is a option for disabling this check in cases where the
1731        string is known to be correct and/or the maximum performance is wanted.
1732    
1733    11. In response to a bug report, I changed one line in Makefile.in from
1734    
1735            -Wl,--out-implib,.libs/lib@WIN_PREFIX@pcreposix.dll.a \
1736        to
1737            -Wl,--out-implib,.libs/@WIN_PREFIX@libpcreposix.dll.a \
1738    
1739        to look similar to other lines, but I have no way of telling whether this
1740        is the right thing to do, as I do not use Windows. No doubt I'll get told
1741        if it's wrong...
1742    
1743    
1744    Version 4.3 21-May-03
1745    ---------------------
1746    
1747    1. Two instances of @WIN_PREFIX@ omitted from the Windows targets in the
1748       Makefile.
1749    
1750    2. Some refactoring to improve the quality of the code:
1751    
1752       (i)   The utf8_table... variables are now declared "const".
1753    
1754       (ii)  The code for \cx, which used the "case flipping" table to upper case
1755             lower case letters, now just substracts 32. This is ASCII-specific,
1756             but the whole concept of \cx is ASCII-specific, so it seems
1757             reasonable.
1758    
1759       (iii) PCRE was using its character types table to recognize decimal and
1760             hexadecimal digits in the pattern. This is silly, because it handles
1761             only 0-9, a-f, and A-F, but the character types table is locale-
1762             specific, which means strange things might happen. A private
1763             table is now used for this - though it costs 256 bytes, a table is
1764             much faster than multiple explicit tests. Of course, the standard
1765             character types table is still used for matching digits in subject
1766             strings against \d.
1767    
1768       (iv)  Strictly, the identifier ESC_t is reserved by POSIX (all identifiers
1769             ending in _t are). So I've renamed it as ESC_tee.
1770    
1771    3. The first argument for regexec() in the POSIX wrapper should have been
1772       defined as "const".
1773    
1774    4. Changed pcretest to use malloc() for its buffers so that they can be
1775       Electric Fenced for debugging.
1776    
1777    5. There were several places in the code where, in UTF-8 mode, PCRE would try
1778       to read one or more bytes before the start of the subject string. Often this
1779       had no effect on PCRE's behaviour, but in some circumstances it could
1780       provoke a segmentation fault.
1781    
1782    6. A lookbehind at the start of a pattern in UTF-8 mode could also cause PCRE
1783       to try to read one or more bytes before the start of the subject string.
1784    
1785    7. A lookbehind in a pattern matched in non-UTF-8 mode on a PCRE compiled with
1786       UTF-8 support could misbehave in various ways if the subject string
1787       contained bytes with the 0x80 bit set and the 0x40 bit unset in a lookbehind
1788       area. (PCRE was not checking for the UTF-8 mode flag, and trying to move
1789       back over UTF-8 characters.)
1790    
1791    
1792  Version 4.2 14-Apr-03  Version 4.2 14-Apr-03
1793  ---------------------  ---------------------
1794    

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