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

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