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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
3    
4  Version 7.3 05-Jul-07  Version 8.01 11-Dec-09
5    ----------------------
6    
7    1.  If a pattern contained a conditional subpattern with only one branch (in
8        particular, this includes all (DEFINE) patterns), a call to pcre_study()
9        computed the wrong minimum data length (which is of course zero for such
10        subpatterns).
11    
12    2.  For patterns such as (?i)a(?-i)b|c where an option setting at the start of
13        the pattern is reset in the first branch, pcre_compile() failed with
14        "internal error: code overflow at offset...". This happened only when
15        the reset was to the original external option setting. (An optimization
16        abstracts leading options settings into an external setting, which was the
17        cause of this.)
18    
19    3.  A pattern such as ^(?!a(*SKIP)b) where a negative assertion contained one
20        of the verbs SKIP, PRUNE, or COMMIT, did not work correctly. When the
21        assertion pattern did not match (meaning that the assertion was true), it
22        was incorrectly treated as false if the SKIP had been reached during the
23        matching. This also applied to assertions used as conditions.
24    
25    4.  If an item that is not supported by pcre_dfa_exec() was encountered in an
26        assertion subpattern, including such a pattern used as a condition,
27        unpredictable results occurred, instead of the error return
28        PCRE_ERROR_DFA_UITEM.
29    
30    5.  The C++ GlobalReplace function was not working like Perl for the special
31        situation when an empty string is matched. It now does the fancy magic
32        stuff that is necessary.
33    
34    6.  In pcre_internal.h, obsolete includes to setjmp.h and stdarg.h have been
35        removed. (These were left over from very, very early versions of PCRE.)
36    
37    7.  Some cosmetic changes to the code to make life easier when compiling it
38        as part of something else:
39    
40        (a) Change DEBUG to PCRE_DEBUG.
41    
42        (b) In pcre_compile(), rename the member of the "branch_chain" structure
43            called "current" as "current_branch", to prevent a collision with the
44            Linux macro when compiled as a kernel module.
45    
46        (c) In pcre_study(), rename the function set_bit() as set_table_bit(), to
47            prevent a collision with the Linux macro when compiled as a kernel
48            module.
49    
50    8.  In pcre_compile() there are some checks for integer overflows that used to
51        cast potentially large values to (double). This has been changed to that
52        when building, a check for int64_t is made, and if it is found, it is used
53        instead, thus avoiding the use of floating point arithmetic. (There is no
54        other use of FP in PCRE.) If int64_t is not found, the fallback is to
55        double.
56    
57    9.  Added two casts to avoid signed/unsigned warnings from VS Studio Express
58        2005 (difference between two addresses compared to an unsigned value).
59    
60    10. Change the standard AC_CHECK_LIB test for libbz2 in configure.ac to a
61        custom one, because of the following reported problem in Windows:
62    
63          - libbz2 uses the Pascal calling convention (WINAPI) for the functions
64            under Win32.
65          - The standard autoconf AC_CHECK_LIB fails to include "bzlib.h",
66            therefore missing the function definition.
67          - The compiler thus generates a "C" signature for the test function.
68          - The linker fails to find the "C" function.
69          - PCRE fails to configure if asked to do so against libbz2.
70    
71    11. When running libtoolize from libtool-2.2.6b as part of autogen.sh, these
72        messages were output:
73    
74          Consider adding `AC_CONFIG_MACRO_DIR([m4])' to configure.ac and
75          rerunning libtoolize, to keep the correct libtool macros in-tree.
76          Consider adding `-I m4' to ACLOCAL_AMFLAGS in Makefile.am.
77    
78        I have done both of these things.
79    
80    12. Although pcre_dfa_exec() does not use nearly as much stack as pcre_exec()
81        most of the time, it *can* run out if it is given a pattern that contains a
82        runaway infinite recursion. I updated the discussion in the pcrestack man
83        page.
84    
85    13. Now that we have gone to the x.xx style of version numbers, the minor
86        version may start with zero. Using 08 or 09 is a bad idea because users
87        might check the value of PCRE_MINOR in their code, and 08 or 09 may be
88        interpreted as invalid octal numbers. I've updated the previous comment in
89        configure.ac, and also added a check that gives an error if 08 or 09 are
90        used.
91    
92    14. Change 8.00/11 was not quite complete: code had been accidentally omitted,
93        causing partial matching to fail where the end of the subject matched \W.
94    
95    
96    
97    Version 8.00 19-Oct-09
98    ----------------------
99    
100    1.  The table for translating pcre_compile() error codes into POSIX error codes
101        was out-of-date, and there was no check on the pcre_compile() error code
102        being within the table. This could lead to an OK return being given in
103        error.
104    
105    2.  Changed the call to open a subject file in pcregrep from fopen(pathname,
106        "r") to fopen(pathname, "rb"), which fixed a problem with some of the tests
107        in a Windows environment.
108    
109    3.  The pcregrep --count option prints the count for each file even when it is
110        zero, as does GNU grep. However, pcregrep was also printing all files when
111        --files-with-matches was added. Now, when both options are given, it prints
112        counts only for those files that have at least one match. (GNU grep just
113        prints the file name in this circumstance, but including the count seems
114        more useful - otherwise, why use --count?) Also ensured that the
115        combination -clh just lists non-zero counts, with no names.
116    
117    4.  The long form of the pcregrep -F option was incorrectly implemented as
118        --fixed_strings instead of --fixed-strings. This is an incompatible change,
119        but it seems right to fix it, and I didn't think it was worth preserving
120        the old behaviour.
121    
122    5.  The command line items --regex=pattern and --regexp=pattern were not
123        recognized by pcregrep, which required --regex pattern or --regexp pattern
124        (with a space rather than an '='). The man page documented the '=' forms,
125        which are compatible with GNU grep; these now work.
126    
127    6.  No libpcreposix.pc file was created for pkg-config; there was just
128        libpcre.pc and libpcrecpp.pc. The omission has been rectified.
129    
130    7.  Added #ifndef SUPPORT_UCP into the pcre_ucd.c module, to reduce its size
131        when UCP support is not needed, by modifying the Python script that
132        generates it from Unicode data files. This should not matter if the module
133        is correctly used as a library, but I received one complaint about 50K of
134        unwanted data. My guess is that the person linked everything into his
135        program rather than using a library. Anyway, it does no harm.
136    
137    8.  A pattern such as /\x{123}{2,2}+/8 was incorrectly compiled; the trigger
138        was a minimum greater than 1 for a wide character in a possessive
139        repetition. The same bug could also affect patterns like /(\x{ff}{0,2})*/8
140        which had an unlimited repeat of a nested, fixed maximum repeat of a wide
141        character. Chaos in the form of incorrect output or a compiling loop could
142        result.
143    
144    9.  The restrictions on what a pattern can contain when partial matching is
145        requested for pcre_exec() have been removed. All patterns can now be
146        partially matched by this function. In addition, if there are at least two
147        slots in the offset vector, the offset of the earliest inspected character
148        for the match and the offset of the end of the subject are set in them when
149        PCRE_ERROR_PARTIAL is returned.
150    
151    10. Partial matching has been split into two forms: PCRE_PARTIAL_SOFT, which is
152        synonymous with PCRE_PARTIAL, for backwards compatibility, and
153        PCRE_PARTIAL_HARD, which causes a partial match to supersede a full match,
154        and may be more useful for multi-segment matching.
155    
156    11. Partial matching with pcre_exec() is now more intuitive. A partial match
157        used to be given if ever the end of the subject was reached; now it is
158        given only if matching could not proceed because another character was
159        needed. This makes a difference in some odd cases such as Z(*FAIL) with the
160        string "Z", which now yields "no match" instead of "partial match". In the
161        case of pcre_dfa_exec(), "no match" is given if every matching path for the
162        final character ended with (*FAIL).
163    
164    12. Restarting a match using pcre_dfa_exec() after a partial match did not work
165        if the pattern had a "must contain" character that was already found in the
166        earlier partial match, unless partial matching was again requested. For
167        example, with the pattern /dog.(body)?/, the "must contain" character is
168        "g". If the first part-match was for the string "dog", restarting with
169        "sbody" failed. This bug has been fixed.
170    
171    13. The string returned by pcre_dfa_exec() after a partial match has been
172        changed so that it starts at the first inspected character rather than the
173        first character of the match. This makes a difference only if the pattern
174        starts with a lookbehind assertion or \b or \B (\K is not supported by
175        pcre_dfa_exec()). It's an incompatible change, but it makes the two
176        matching functions compatible, and I think it's the right thing to do.
177    
178    14. Added a pcredemo man page, created automatically from the pcredemo.c file,
179        so that the demonstration program is easily available in environments where
180        PCRE has not been installed from source.
181    
182    15. Arranged to add -DPCRE_STATIC to cflags in libpcre.pc, libpcreposix.cp,
183        libpcrecpp.pc and pcre-config when PCRE is not compiled as a shared
184        library.
185    
186    16. Added REG_UNGREEDY to the pcreposix interface, at the request of a user.
187        It maps to PCRE_UNGREEDY. It is not, of course, POSIX-compatible, but it
188        is not the first non-POSIX option to be added. Clearly some people find
189        these options useful.
190    
191    17. If a caller to the POSIX matching function regexec() passes a non-zero
192        value for nmatch with a NULL value for pmatch, the value of
193        nmatch is forced to zero.
194    
195    18. RunGrepTest did not have a test for the availability of the -u option of
196        the diff command, as RunTest does. It now checks in the same way as
197        RunTest, and also checks for the -b option.
198    
199    19. If an odd number of negated classes containing just a single character
200        interposed, within parentheses, between a forward reference to a named
201        subpattern and the definition of the subpattern, compilation crashed with
202        an internal error, complaining that it could not find the referenced
203        subpattern. An example of a crashing pattern is /(?&A)(([^m])(?<A>))/.
204        [The bug was that it was starting one character too far in when skipping
205        over the character class, thus treating the ] as data rather than
206        terminating the class. This meant it could skip too much.]
207    
208    20. Added PCRE_NOTEMPTY_ATSTART in order to be able to correctly implement the
209        /g option in pcretest when the pattern contains \K, which makes it possible
210        to have an empty string match not at the start, even when the pattern is
211        anchored. Updated pcretest and pcredemo to use this option.
212    
213    21. If the maximum number of capturing subpatterns in a recursion was greater
214        than the maximum at the outer level, the higher number was returned, but
215        with unset values at the outer level. The correct (outer level) value is
216        now given.
217    
218    22. If (*ACCEPT) appeared inside capturing parentheses, previous releases of
219        PCRE did not set those parentheses (unlike Perl). I have now found a way to
220        make it do so. The string so far is captured, making this feature
221        compatible with Perl.
222    
223    23. The tests have been re-organized, adding tests 11 and 12, to make it
224        possible to check the Perl 5.10 features against Perl 5.10.
225    
226    24. Perl 5.10 allows subroutine calls in lookbehinds, as long as the subroutine
227        pattern matches a fixed length string. PCRE did not allow this; now it
228        does. Neither allows recursion.
229    
230    25. I finally figured out how to implement a request to provide the minimum
231        length of subject string that was needed in order to match a given pattern.
232        (It was back references and recursion that I had previously got hung up
233        on.) This code has now been added to pcre_study(); it finds a lower bound
234        to the length of subject needed. It is not necessarily the greatest lower
235        bound, but using it to avoid searching strings that are too short does give
236        some useful speed-ups. The value is available to calling programs via
237        pcre_fullinfo().
238    
239    26. While implementing 25, I discovered to my embarrassment that pcretest had
240        not been passing the result of pcre_study() to pcre_dfa_exec(), so the
241        study optimizations had never been tested with that matching function.
242        Oops. What is worse, even when it was passed study data, there was a bug in
243        pcre_dfa_exec() that meant it never actually used it. Double oops. There
244        were also very few tests of studied patterns with pcre_dfa_exec().
245    
246    27. If (?| is used to create subpatterns with duplicate numbers, they are now
247        allowed to have the same name, even if PCRE_DUPNAMES is not set. However,
248        on the other side of the coin, they are no longer allowed to have different
249        names, because these cannot be distinguished in PCRE, and this has caused
250        confusion. (This is a difference from Perl.)
251    
252    28. When duplicate subpattern names are present (necessarily with different
253        numbers, as required by 27 above), and a test is made by name in a
254        conditional pattern, either for a subpattern having been matched, or for
255        recursion in such a pattern, all the associated numbered subpatterns are
256        tested, and the overall condition is true if the condition is true for any
257        one of them. This is the way Perl works, and is also more like the way
258        testing by number works.
259    
260    
261    Version 7.9 11-Apr-09
262    ---------------------
263    
264    1.  When building with support for bzlib/zlib (pcregrep) and/or readline
265        (pcretest), all targets were linked against these libraries. This included
266        libpcre, libpcreposix, and libpcrecpp, even though they do not use these
267        libraries. This caused unwanted dependencies to be created. This problem
268        has been fixed, and now only pcregrep is linked with bzlib/zlib and only
269        pcretest is linked with readline.
270    
271    2.  The "typedef int BOOL" in pcre_internal.h that was included inside the
272        "#ifndef FALSE" condition by an earlier change (probably 7.8/18) has been
273        moved outside it again, because FALSE and TRUE are already defined in AIX,
274        but BOOL is not.
275    
276    3.  The pcre_config() function was treating the PCRE_MATCH_LIMIT and
277        PCRE_MATCH_LIMIT_RECURSION values as ints, when they should be long ints.
278    
279    4.  The pcregrep documentation said spaces were inserted as well as colons (or
280        hyphens) following file names and line numbers when outputting matching
281        lines. This is not true; no spaces are inserted. I have also clarified the
282        wording for the --colour (or --color) option.
283    
284    5.  In pcregrep, when --colour was used with -o, the list of matching strings
285        was not coloured; this is different to GNU grep, so I have changed it to be
286        the same.
287    
288    6.  When --colo(u)r was used in pcregrep, only the first matching substring in
289        each matching line was coloured. Now it goes on to look for further matches
290        of any of the test patterns, which is the same behaviour as GNU grep.
291    
292    7.  A pattern that could match an empty string could cause pcregrep to loop; it
293        doesn't make sense to accept an empty string match in pcregrep, so I have
294        locked it out (using PCRE's PCRE_NOTEMPTY option). By experiment, this
295        seems to be how GNU grep behaves.
296    
297    8.  The pattern (?(?=.*b)b|^) was incorrectly compiled as "match must be at
298        start or after a newline", because the conditional assertion was not being
299        correctly handled. The rule now is that both the assertion and what follows
300        in the first alternative must satisfy the test.
301    
302    9.  If auto-callout was enabled in a pattern with a conditional group whose
303        condition was an assertion, PCRE could crash during matching, both with
304        pcre_exec() and pcre_dfa_exec().
305    
306    10. The PCRE_DOLLAR_ENDONLY option was not working when pcre_dfa_exec() was
307        used for matching.
308    
309    11. Unicode property support in character classes was not working for
310        characters (bytes) greater than 127 when not in UTF-8 mode.
311    
312    12. Added the -M command line option to pcretest.
313    
314    14. Added the non-standard REG_NOTEMPTY option to the POSIX interface.
315    
316    15. Added the PCRE_NO_START_OPTIMIZE match-time option.
317    
318    16. Added comments and documentation about mis-use of no_arg in the C++
319        wrapper.
320    
321    17. Implemented support for UTF-8 encoding in EBCDIC environments, a patch
322        from Martin Jerabek that uses macro names for all relevant character and
323        string constants.
324    
325    18. Added to pcre_internal.h two configuration checks: (a) If both EBCDIC and
326        SUPPORT_UTF8 are set, give an error; (b) If SUPPORT_UCP is set without
327        SUPPORT_UTF8, define SUPPORT_UTF8. The "configure" script handles both of
328        these, but not everybody uses configure.
329    
330    19. A conditional group that had only one branch was not being correctly
331        recognized as an item that could match an empty string. This meant that an
332        enclosing group might also not be so recognized, causing infinite looping
333        (and probably a segfault) for patterns such as ^"((?(?=[a])[^"])|b)*"$
334        with the subject "ab", where knowledge that the repeated group can match
335        nothing is needed in order to break the loop.
336    
337    20. If a pattern that was compiled with callouts was matched using pcre_dfa_
338        exec(), but without supplying a callout function, matching went wrong.
339    
340    21. If PCRE_ERROR_MATCHLIMIT occurred during a recursion, there was a memory
341        leak if the size of the offset vector was greater than 30. When the vector
342        is smaller, the saved offsets during recursion go onto a local stack
343        vector, but for larger vectors malloc() is used. It was failing to free
344        when the recursion yielded PCRE_ERROR_MATCH_LIMIT (or any other "abnormal"
345        error, in fact).
346    
347    22. There was a missing #ifdef SUPPORT_UTF8 round one of the variables in the
348        heapframe that is used only when UTF-8 support is enabled. This caused no
349        problem, but was untidy.
350    
351    23. Steven Van Ingelgem's patch to CMakeLists.txt to change the name
352        CMAKE_BINARY_DIR to PROJECT_BINARY_DIR so that it works when PCRE is
353        included within another project.
354    
355    24. Steven Van Ingelgem's patches to add more options to the CMake support,
356        slightly modified by me:
357    
358          (a) PCRE_BUILD_TESTS can be set OFF not to build the tests, including
359              not building pcregrep.
360    
361          (b) PCRE_BUILD_PCREGREP can be see OFF not to build pcregrep, but only
362              if PCRE_BUILD_TESTS is also set OFF, because the tests use pcregrep.
363    
364    25. Forward references, both numeric and by name, in patterns that made use of
365        duplicate group numbers, could behave incorrectly or give incorrect errors,
366        because when scanning forward to find the reference group, PCRE was not
367        taking into account the duplicate group numbers. A pattern such as
368        ^X(?3)(a)(?|(b)|(q))(Y) is an example.
369    
370    26. Changed a few more instances of "const unsigned char *" to USPTR, making
371        the feature of a custom pointer more persuasive (as requested by a user).
372    
373    27. Wrapped the definitions of fileno and isatty for Windows, which appear in
374        pcretest.c, inside #ifndefs, because it seems they are sometimes already
375        pre-defined.
376    
377    28. Added support for (*UTF8) at the start of a pattern.
378    
379    29. Arrange for flags added by the "release type" setting in CMake to be shown
380        in the configuration summary.
381    
382    
383    Version 7.8 05-Sep-08
384    ---------------------
385    
386    1.  Replaced UCP searching code with optimized version as implemented for Ad
387        Muncher (http://www.admuncher.com/) by Peter Kankowski. This uses a two-
388        stage table and inline lookup instead of a function, giving speed ups of 2
389        to 5 times on some simple patterns that I tested. Permission was given to
390        distribute the MultiStage2.py script that generates the tables (it's not in
391        the tarball, but is in the Subversion repository).
392    
393    2.  Updated the Unicode datatables to Unicode 5.1.0. This adds yet more
394        scripts.
395    
396    3.  Change 12 for 7.7 introduced a bug in pcre_study() when a pattern contained
397        a group with a zero qualifier. The result of the study could be incorrect,
398        or the function might crash, depending on the pattern.
399    
400    4.  Caseless matching was not working for non-ASCII characters in back
401        references. For example, /(\x{de})\1/8i was not matching \x{de}\x{fe}.
402        It now works when Unicode Property Support is available.
403    
404    5.  In pcretest, an escape such as \x{de} in the data was always generating
405        a UTF-8 string, even in non-UTF-8 mode. Now it generates a single byte in
406        non-UTF-8 mode. If the value is greater than 255, it gives a warning about
407        truncation.
408    
409    6.  Minor bugfix in pcrecpp.cc (change "" == ... to NULL == ...).
410    
411    7.  Added two (int) casts to pcregrep when printing the difference of two
412        pointers, in case they are 64-bit values.
413    
414    8.  Added comments about Mac OS X stack usage to the pcrestack man page and to
415        test 2 if it fails.
416    
417    9.  Added PCRE_CALL_CONVENTION just before the names of all exported functions,
418        and a #define of that name to empty if it is not externally set. This is to
419        allow users of MSVC to set it if necessary.
420    
421    10. The PCRE_EXP_DEFN macro which precedes exported functions was missing from
422        the convenience functions in the pcre_get.c source file.
423    
424    11. An option change at the start of a pattern that had top-level alternatives
425        could cause overwriting and/or a crash. This command provoked a crash in
426        some environments:
427    
428          printf "/(?i)[\xc3\xa9\xc3\xbd]|[\xc3\xa9\xc3\xbdA]/8\n" | pcretest
429    
430        This potential security problem was recorded as CVE-2008-2371.
431    
432    12. For a pattern where the match had to start at the beginning or immediately
433        after a newline (e.g /.*anything/ without the DOTALL flag), pcre_exec() and
434        pcre_dfa_exec() could read past the end of the passed subject if there was
435        no match. To help with detecting such bugs (e.g. with valgrind), I modified
436        pcretest so that it places the subject at the end of its malloc-ed buffer.
437    
438    13. The change to pcretest in 12 above threw up a couple more cases when pcre_
439        exec() might read past the end of the data buffer in UTF-8 mode.
440    
441    14. A similar bug to 7.3/2 existed when the PCRE_FIRSTLINE option was set and
442        the data contained the byte 0x85 as part of a UTF-8 character within its
443        first line. This applied both to normal and DFA matching.
444    
445    15. Lazy qualifiers were not working in some cases in UTF-8 mode. For example,
446        /^[^d]*?$/8 failed to match "abc".
447    
448    16. Added a missing copyright notice to pcrecpp_internal.h.
449    
450    17. Make it more clear in the documentation that values returned from
451        pcre_exec() in ovector are byte offsets, not character counts.
452    
453    18. Tidied a few places to stop certain compilers from issuing warnings.
454    
455    19. Updated the Virtual Pascal + BCC files to compile the latest v7.7, as
456        supplied by Stefan Weber. I made a further small update for 7.8 because
457        there is a change of source arrangements: the pcre_searchfuncs.c module is
458        replaced by pcre_ucd.c.
459    
460    
461    Version 7.7 07-May-08
462    ---------------------
463    
464    1.  Applied Craig's patch to sort out a long long problem: "If we can't convert
465        a string to a long long, pretend we don't even have a long long." This is
466        done by checking for the strtoq, strtoll, and _strtoi64 functions.
467    
468    2.  Applied Craig's patch to pcrecpp.cc to restore ABI compatibility with
469        pre-7.6 versions, which defined a global no_arg variable instead of putting
470        it in the RE class. (See also #8 below.)
471    
472    3.  Remove a line of dead code, identified by coverity and reported by Nuno
473        Lopes.
474    
475    4.  Fixed two related pcregrep bugs involving -r with --include or --exclude:
476    
477        (1) The include/exclude patterns were being applied to the whole pathnames
478            of files, instead of just to the final components.
479    
480        (2) If there was more than one level of directory, the subdirectories were
481            skipped unless they satisfied the include/exclude conditions. This is
482            inconsistent with GNU grep (and could even be seen as contrary to the
483            pcregrep specification - which I improved to make it absolutely clear).
484            The action now is always to scan all levels of directory, and just
485            apply the include/exclude patterns to regular files.
486    
487    5.  Added the --include_dir and --exclude_dir patterns to pcregrep, and used
488        --exclude_dir in the tests to avoid scanning .svn directories.
489    
490    6.  Applied Craig's patch to the QuoteMeta function so that it escapes the
491        NUL character as backslash + 0 rather than backslash + NUL, because PCRE
492        doesn't support NULs in patterns.
493    
494    7.  Added some missing "const"s to declarations of static tables in
495        pcre_compile.c and pcre_dfa_exec.c.
496    
497    8.  Applied Craig's patch to pcrecpp.cc to fix a problem in OS X that was
498        caused by fix #2  above. (Subsequently also a second patch to fix the
499        first patch. And a third patch - this was a messy problem.)
500    
501    9.  Applied Craig's patch to remove the use of push_back().
502    
503    10. Applied Alan Lehotsky's patch to add REG_STARTEND support to the POSIX
504        matching function regexec().
505    
506    11. Added support for the Oniguruma syntax \g<name>, \g<n>, \g'name', \g'n',
507        which, however, unlike Perl's \g{...}, are subroutine calls, not back
508        references. PCRE supports relative numbers with this syntax (I don't think
509        Oniguruma does).
510    
511    12. Previously, a group with a zero repeat such as (...){0} was completely
512        omitted from the compiled regex. However, this means that if the group
513        was called as a subroutine from elsewhere in the pattern, things went wrong
514        (an internal error was given). Such groups are now left in the compiled
515        pattern, with a new opcode that causes them to be skipped at execution
516        time.
517    
518    13. Added the PCRE_JAVASCRIPT_COMPAT option. This makes the following changes
519        to the way PCRE behaves:
520    
521        (a) A lone ] character is dis-allowed (Perl treats it as data).
522    
523        (b) A back reference to an unmatched subpattern matches an empty string
524            (Perl fails the current match path).
525    
526        (c) A data ] in a character class must be notated as \] because if the
527            first data character in a class is ], it defines an empty class. (In
528            Perl it is not possible to have an empty class.) The empty class []
529            never matches; it forces failure and is equivalent to (*FAIL) or (?!).
530            The negative empty class [^] matches any one character, independently
531            of the DOTALL setting.
532    
533    14. A pattern such as /(?2)[]a()b](abc)/ which had a forward reference to a
534        non-existent subpattern following a character class starting with ']' and
535        containing () gave an internal compiling error instead of "reference to
536        non-existent subpattern". Fortunately, when the pattern did exist, the
537        compiled code was correct. (When scanning forwards to check for the
538        existencd of the subpattern, it was treating the data ']' as terminating
539        the class, so got the count wrong. When actually compiling, the reference
540        was subsequently set up correctly.)
541    
542    15. The "always fail" assertion (?!) is optimzed to (*FAIL) by pcre_compile;
543        it was being rejected as not supported by pcre_dfa_exec(), even though
544        other assertions are supported. I have made pcre_dfa_exec() support
545        (*FAIL).
546    
547    16. The implementation of 13c above involved the invention of a new opcode,
548        OP_ALLANY, which is like OP_ANY but doesn't check the /s flag. Since /s
549        cannot be changed at match time, I realized I could make a small
550        improvement to matching performance by compiling OP_ALLANY instead of
551        OP_ANY for "." when DOTALL was set, and then removing the runtime tests
552        on the OP_ANY path.
553    
554    17. Compiling pcretest on Windows with readline support failed without the
555        following two fixes: (1) Make the unistd.h include conditional on
556        HAVE_UNISTD_H; (2) #define isatty and fileno as _isatty and _fileno.
557    
558    18. Changed CMakeLists.txt and cmake/FindReadline.cmake to arrange for the
559        ncurses library to be included for pcretest when ReadLine support is
560        requested, but also to allow for it to be overridden. This patch came from
561        Daniel Bergström.
562    
563    19. There was a typo in the file ucpinternal.h where f0_rangeflag was defined
564        as 0x00f00000 instead of 0x00800000. Luckily, this would not have caused
565        any errors with the current Unicode tables. Thanks to Peter Kankowski for
566        spotting this.
567    
568    
569    Version 7.6 28-Jan-08
570    ---------------------
571    
572    1.  A character class containing a very large number of characters with
573        codepoints greater than 255 (in UTF-8 mode, of course) caused a buffer
574        overflow.
575    
576    2.  Patch to cut out the "long long" test in pcrecpp_unittest when
577        HAVE_LONG_LONG is not defined.
578    
579    3.  Applied Christian Ehrlicher's patch to update the CMake build files to
580        bring them up to date and include new features. This patch includes:
581    
582        - Fixed PH's badly added libz and libbz2 support.
583        - Fixed a problem with static linking.
584        - Added pcredemo. [But later removed - see 7 below.]
585        - Fixed dftables problem and added an option.
586        - Added a number of HAVE_XXX tests, including HAVE_WINDOWS_H and
587            HAVE_LONG_LONG.
588        - Added readline support for pcretest.
589        - Added an listing of the option settings after cmake has run.
590    
591    4.  A user submitted a patch to Makefile that makes it easy to create
592        "pcre.dll" under mingw when using Configure/Make. I added stuff to
593        Makefile.am that cause it to include this special target, without
594        affecting anything else. Note that the same mingw target plus all
595        the other distribution libraries and programs are now supported
596        when configuring with CMake (see 6 below) instead of with
597        Configure/Make.
598    
599    5.  Applied Craig's patch that moves no_arg into the RE class in the C++ code.
600        This is an attempt to solve the reported problem "pcrecpp::no_arg is not
601        exported in the Windows port". It has not yet been confirmed that the patch
602        solves the problem, but it does no harm.
603    
604    6.  Applied Sheri's patch to CMakeLists.txt to add NON_STANDARD_LIB_PREFIX and
605        NON_STANDARD_LIB_SUFFIX for dll names built with mingw when configured
606        with CMake, and also correct the comment about stack recursion.
607    
608    7.  Remove the automatic building of pcredemo from the ./configure system and
609        from CMakeLists.txt. The whole idea of pcredemo.c is that it is an example
610        of a program that users should build themselves after PCRE is installed, so
611        building it automatically is not really right. What is more, it gave
612        trouble in some build environments.
613    
614    8.  Further tidies to CMakeLists.txt from Sheri and Christian.
615    
616    
617    Version 7.5 10-Jan-08
618    ---------------------
619    
620    1.  Applied a patch from Craig: "This patch makes it possible to 'ignore'
621        values in parens when parsing an RE using the C++ wrapper."
622    
623    2.  Negative specials like \S did not work in character classes in UTF-8 mode.
624        Characters greater than 255 were excluded from the class instead of being
625        included.
626    
627    3.  The same bug as (2) above applied to negated POSIX classes such as
628        [:^space:].
629    
630    4.  PCRECPP_STATIC was referenced in pcrecpp_internal.h, but nowhere was it
631        defined or documented. It seems to have been a typo for PCRE_STATIC, so
632        I have changed it.
633    
634    5.  The construct (?&) was not diagnosed as a syntax error (it referenced the
635        first named subpattern) and a construct such as (?&a) would reference the
636        first named subpattern whose name started with "a" (in other words, the
637        length check was missing). Both these problems are fixed. "Subpattern name
638        expected" is now given for (?&) (a zero-length name), and this patch also
639        makes it give the same error for \k'' (previously it complained that that
640        was a reference to a non-existent subpattern).
641    
642    6.  The erroneous patterns (?+-a) and (?-+a) give different error messages;
643        this is right because (?- can be followed by option settings as well as by
644        digits. I have, however, made the messages clearer.
645    
646    7.  Patterns such as (?(1)a|b) (a pattern that contains fewer subpatterns
647        than the number used in the conditional) now cause a compile-time error.
648        This is actually not compatible with Perl, which accepts such patterns, but
649        treats the conditional as always being FALSE (as PCRE used to), but it
650        seems to me that giving a diagnostic is better.
651    
652    8.  Change "alphameric" to the more common word "alphanumeric" in comments
653        and messages.
654    
655    9.  Fix two occurrences of "backslash" in comments that should have been
656        "backspace".
657    
658    10. Remove two redundant lines of code that can never be obeyed (their function
659        was moved elsewhere).
660    
661    11. The program that makes PCRE's Unicode character property table had a bug
662        which caused it to generate incorrect table entries for sequences of
663        characters that have the same character type, but are in different scripts.
664        It amalgamated them into a single range, with the script of the first of
665        them. In other words, some characters were in the wrong script. There were
666        thirteen such cases, affecting characters in the following ranges:
667    
668          U+002b0 - U+002c1
669          U+0060c - U+0060d
670          U+0061e - U+00612
671          U+0064b - U+0065e
672          U+0074d - U+0076d
673          U+01800 - U+01805
674          U+01d00 - U+01d77
675          U+01d9b - U+01dbf
676          U+0200b - U+0200f
677          U+030fc - U+030fe
678          U+03260 - U+0327f
679          U+0fb46 - U+0fbb1
680          U+10450 - U+1049d
681    
682    12. The -o option (show only the matching part of a line) for pcregrep was not
683        compatible with GNU grep in that, if there was more than one match in a
684        line, it showed only the first of them. It now behaves in the same way as
685        GNU grep.
686    
687    13. If the -o and -v options were combined for pcregrep, it printed a blank
688        line for every non-matching line. GNU grep prints nothing, and pcregrep now
689        does the same. The return code can be used to tell if there were any
690        non-matching lines.
691    
692    14. Added --file-offsets and --line-offsets to pcregrep.
693    
694    15. The pattern (?=something)(?R) was not being diagnosed as a potentially
695        infinitely looping recursion. The bug was that positive lookaheads were not
696        being skipped when checking for a possible empty match (negative lookaheads
697        and both kinds of lookbehind were skipped).
698    
699    16. Fixed two typos in the Windows-only code in pcregrep.c, and moved the
700        inclusion of <windows.h> to before rather than after the definition of
701        INVALID_FILE_ATTRIBUTES (patch from David Byron).
702    
703    17. Specifying a possessive quantifier with a specific limit for a Unicode
704        character property caused pcre_compile() to compile bad code, which led at
705        runtime to PCRE_ERROR_INTERNAL (-14). Examples of patterns that caused this
706        are: /\p{Zl}{2,3}+/8 and /\p{Cc}{2}+/8. It was the possessive "+" that
707        caused the error; without that there was no problem.
708    
709    18. Added --enable-pcregrep-libz and --enable-pcregrep-libbz2.
710    
711    19. Added --enable-pcretest-libreadline.
712    
713    20. In pcrecpp.cc, the variable 'count' was incremented twice in
714        RE::GlobalReplace(). As a result, the number of replacements returned was
715        double what it should be. I removed one of the increments, but Craig sent a
716        later patch that removed the other one (the right fix) and added unit tests
717        that check the return values (which was not done before).
718    
719    21. Several CMake things:
720    
721        (1) Arranged that, when cmake is used on Unix, the libraries end up with
722            the names libpcre and libpcreposix, not just pcre and pcreposix.
723    
724        (2) The above change means that pcretest and pcregrep are now correctly
725            linked with the newly-built libraries, not previously installed ones.
726    
727        (3) Added PCRE_SUPPORT_LIBREADLINE, PCRE_SUPPORT_LIBZ, PCRE_SUPPORT_LIBBZ2.
728    
729    22. In UTF-8 mode, with newline set to "any", a pattern such as .*a.*=.b.*
730        crashed when matching a string such as a\x{2029}b (note that \x{2029} is a
731        UTF-8 newline character). The key issue is that the pattern starts .*;
732        this means that the match must be either at the beginning, or after a
733        newline. The bug was in the code for advancing after a failed match and
734        checking that the new position followed a newline. It was not taking
735        account of UTF-8 characters correctly.
736    
737    23. PCRE was behaving differently from Perl in the way it recognized POSIX
738        character classes. PCRE was not treating the sequence [:...:] as a
739        character class unless the ... were all letters. Perl, however, seems to
740        allow any characters between [: and :], though of course it rejects as
741        unknown any "names" that contain non-letters, because all the known class
742        names consist only of letters. Thus, Perl gives an error for [[:1234:]],
743        for example, whereas PCRE did not - it did not recognize a POSIX character
744        class. This seemed a bit dangerous, so the code has been changed to be
745        closer to Perl. The behaviour is not identical to Perl, because PCRE will
746        diagnose an unknown class for, for example, [[:l\ower:]] where Perl will
747        treat it as [[:lower:]]. However, PCRE does now give "unknown" errors where
748        Perl does, and where it didn't before.
749    
750    24. Rewrite so as to remove the single use of %n from pcregrep because in some
751        Windows environments %n is disabled by default.
752    
753    
754    Version 7.4 21-Sep-07
755    ---------------------
756    
757    1.  Change 7.3/28 was implemented for classes by looking at the bitmap. This
758        means that a class such as [\s] counted as "explicit reference to CR or
759        LF". That isn't really right - the whole point of the change was to try to
760        help when there was an actual mention of one of the two characters. So now
761        the change happens only if \r or \n (or a literal CR or LF) character is
762        encountered.
763    
764    2.  The 32-bit options word was also used for 6 internal flags, but the numbers
765        of both had grown to the point where there were only 3 bits left.
766        Fortunately, there was spare space in the data structure, and so I have
767        moved the internal flags into a new 16-bit field to free up more option
768        bits.
769    
770    3.  The appearance of (?J) at the start of a pattern set the DUPNAMES option,
771        but did not set the internal JCHANGED flag - either of these is enough to
772        control the way the "get" function works - but the PCRE_INFO_JCHANGED
773        facility is supposed to tell if (?J) was ever used, so now (?J) at the
774        start sets both bits.
775    
776    4.  Added options (at build time, compile time, exec time) to change \R from
777        matching any Unicode line ending sequence to just matching CR, LF, or CRLF.
778    
779    5.  doc/pcresyntax.html was missing from the distribution.
780    
781    6.  Put back the definition of PCRE_ERROR_NULLWSLIMIT, for backward
782        compatibility, even though it is no longer used.
783    
784    7.  Added macro for snprintf to pcrecpp_unittest.cc and also for strtoll and
785        strtoull to pcrecpp.cc to select the available functions in WIN32 when the
786        windows.h file is present (where different names are used). [This was
787        reversed later after testing - see 16 below.]
788    
789    8.  Changed all #include <config.h> to #include "config.h". There were also
790        some further <pcre.h> cases that I changed to "pcre.h".
791    
792    9.  When pcregrep was used with the --colour option, it missed the line ending
793        sequence off the lines that it output.
794    
795    10. It was pointed out to me that arrays of string pointers cause lots of
796        relocations when a shared library is dynamically loaded. A technique of
797        using a single long string with a table of offsets can drastically reduce
798        these. I have refactored PCRE in four places to do this. The result is
799        dramatic:
800    
801          Originally:                          290
802          After changing UCP table:            187
803          After changing error message table:   43
804          After changing table of "verbs"       36
805          After changing table of Posix names   22
806    
807        Thanks to the folks working on Gregex for glib for this insight.
808    
809    11. --disable-stack-for-recursion caused compiling to fail unless -enable-
810        unicode-properties was also set.
811    
812    12. Updated the tests so that they work when \R is defaulted to ANYCRLF.
813    
814    13. Added checks for ANY and ANYCRLF to pcrecpp.cc where it previously
815        checked only for CRLF.
816    
817    14. Added casts to pcretest.c to avoid compiler warnings.
818    
819    15. Added Craig's patch to various pcrecpp modules to avoid compiler warnings.
820    
821    16. Added Craig's patch to remove the WINDOWS_H tests, that were not working,
822        and instead check for _strtoi64 explicitly, and avoid the use of snprintf()
823        entirely. This removes changes made in 7 above.
824    
825    17. The CMake files have been updated, and there is now more information about
826        building with CMake in the NON-UNIX-USE document.
827    
828    
829    Version 7.3 28-Aug-07
830  ---------------------  ---------------------
831    
832   1. In the rejigging of the build system that eventually resulted in 7.1, the   1. In the rejigging of the build system that eventually resulted in 7.1, the
# Line 64  Version 7.3 05-Jul-07 Line 889  Version 7.3 05-Jul-07
889      dynamic way, which I have now done. The artificial limitation on group      dynamic way, which I have now done. The artificial limitation on group
890      length has been removed - we now have only the limit on the total length of      length has been removed - we now have only the limit on the total length of
891      the compiled pattern, which depends on the LINK_SIZE setting.      the compiled pattern, which depends on the LINK_SIZE setting.
892    
893  10. Fixed a bug in the documentation for get/copy named substring when  10. Fixed a bug in the documentation for get/copy named substring when
894      duplicate names are permitted. If none of the named substrings are set, the      duplicate names are permitted. If none of the named substrings are set, the
895      functions return PCRE_ERROR_NOSUBSTRING (7); the doc said they returned an      functions return PCRE_ERROR_NOSUBSTRING (7); the doc said they returned an
896      empty string.      empty string.
897    
898    11. Because Perl interprets \Q...\E at a high level, and ignores orphan \E
899        instances, patterns such as [\Q\E] or [\E] or even [^\E] cause an error,
900        because the ] is interpreted as the first data character and the
901        terminating ] is not found. PCRE has been made compatible with Perl in this
902        regard. Previously, it interpreted [\Q\E] as an empty class, and [\E] could
903        cause memory overwriting.
904    
905    10. Like Perl, PCRE automatically breaks an unlimited repeat after an empty
906        string has been matched (to stop an infinite loop). It was not recognizing
907        a conditional subpattern that could match an empty string if that
908        subpattern was within another subpattern. For example, it looped when
909        trying to match  (((?(1)X|))*)  but it was OK with  ((?(1)X|)*)  where the
910        condition was not nested. This bug has been fixed.
911    
912    12. A pattern like \X?\d or \P{L}?\d in non-UTF-8 mode could cause a backtrack
913        past the start of the subject in the presence of bytes with the top bit
914        set, for example "\x8aBCD".
915    
916    13. Added Perl 5.10 experimental backtracking controls (*FAIL), (*F), (*PRUNE),
917        (*SKIP), (*THEN), (*COMMIT), and (*ACCEPT).
918    
919    14. Optimized (?!) to (*FAIL).
920    
921    15. Updated the test for a valid UTF-8 string to conform to the later RFC 3629.
922        This restricts code points to be within the range 0 to 0x10FFFF, excluding
923        the "low surrogate" sequence 0xD800 to 0xDFFF. Previously, PCRE allowed the
924        full range 0 to 0x7FFFFFFF, as defined by RFC 2279. Internally, it still
925        does: it's just the validity check that is more restrictive.
926    
927    16. Inserted checks for integer overflows during escape sequence (backslash)
928        processing, and also fixed erroneous offset values for syntax errors during
929        backslash processing.
930    
931    17. Fixed another case of looking too far back in non-UTF-8 mode (cf 12 above)
932        for patterns like [\PPP\x8a]{1,}\x80 with the subject "A\x80".
933    
934    18. An unterminated class in a pattern like (?1)\c[ with a "forward reference"
935        caused an overrun.
936    
937    19. A pattern like (?:[\PPa*]*){8,} which had an "extended class" (one with
938        something other than just ASCII characters) inside a group that had an
939        unlimited repeat caused a loop at compile time (while checking to see
940        whether the group could match an empty string).
941    
942    20. Debugging a pattern containing \p or \P could cause a crash. For example,
943        [\P{Any}] did so. (Error in the code for printing property names.)
944    
945    21. An orphan \E inside a character class could cause a crash.
946    
947    22. A repeated capturing bracket such as (A)? could cause a wild memory
948        reference during compilation.
949    
950    23. There are several functions in pcre_compile() that scan along a compiled
951        expression for various reasons (e.g. to see if it's fixed length for look
952        behind). There were bugs in these functions when a repeated \p or \P was
953        present in the pattern. These operators have additional parameters compared
954        with \d, etc, and these were not being taken into account when moving along
955        the compiled data. Specifically:
956    
957        (a) A item such as \p{Yi}{3} in a lookbehind was not treated as fixed
958            length.
959    
960        (b) An item such as \pL+ within a repeated group could cause crashes or
961            loops.
962    
963        (c) A pattern such as \p{Yi}+(\P{Yi}+)(?1) could give an incorrect
964            "reference to non-existent subpattern" error.
965    
966        (d) A pattern like (\P{Yi}{2}\277)? could loop at compile time.
967    
968    24. A repeated \S or \W in UTF-8 mode could give wrong answers when multibyte
969        characters were involved (for example /\S{2}/8g with "A\x{a3}BC").
970    
971    25. Using pcregrep in multiline, inverted mode (-Mv) caused it to loop.
972    
973    26. Patterns such as [\P{Yi}A] which include \p or \P and just one other
974        character were causing crashes (broken optimization).
975    
976    27. Patterns such as (\P{Yi}*\277)* (group with possible zero repeat containing
977        \p or \P) caused a compile-time loop.
978    
979    28. More problems have arisen in unanchored patterns when CRLF is a valid line
980        break. For example, the unstudied pattern [\r\n]A does not match the string
981        "\r\nA" because change 7.0/46 below moves the current point on by two
982        characters after failing to match at the start. However, the pattern \nA
983        *does* match, because it doesn't start till \n, and if [\r\n]A is studied,
984        the same is true. There doesn't seem any very clean way out of this, but
985        what I have chosen to do makes the common cases work: PCRE now takes note
986        of whether there can be an explicit match for \r or \n anywhere in the
987        pattern, and if so, 7.0/46 no longer applies. As part of this change,
988        there's a new PCRE_INFO_HASCRORLF option for finding out whether a compiled
989        pattern has explicit CR or LF references.
990    
991    29. Added (*CR) etc for changing newline setting at start of pattern.
992    
993    
994  Version 7.2 19-Jun-07  Version 7.2 19-Jun-07

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