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revision 13 by nigel, Sat Feb 24 21:38:21 2007 UTC revision 402 by ph10, Sat Mar 21 17:26:03 2009 UTC
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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
3    
4    Version 7.9 xx-xxx-09
5    ---------------------
6    
7    1.  When building with support for bzlib/zlib (pcregrep) and/or readline
8        (pcretest), all targets were linked against these libraries. This included
9        libpcre, libpcreposix, and libpcrecpp, even though they do not use these
10        libraries. This caused unwanted dependencies to be created. This problem
11        has been fixed, and now only pcregrep is linked with bzlib/zlib and only
12        pcretest is linked with readline.
13    
14    2.  The "typedef int BOOL" in pcre_internal.h that was included inside the
15        "#ifndef FALSE" condition by an earlier change (probably 7.8/18) has been
16        moved outside it again, because FALSE and TRUE are already defined in AIX,
17        but BOOL is not.
18    
19    3.  The pcre_config() function was treating the PCRE_MATCH_LIMIT and
20        PCRE_MATCH_LIMIT_RETURSION values as ints, when they should be long ints.
21    
22    4.  The pcregrep documentation said spaces were inserted as well as colons (or
23        hyphens) following file names and line numbers when outputting matching
24        lines. This is not true; no spaces are inserted. I have also clarified the
25        wording for the --colour (or --color) option.
26    
27    5.  In pcregrep, when --colour was used with -o, the list of matching strings
28        was not coloured; this is different to GNU grep, so I have changed it to be
29        the same.
30    
31    6.  When --colo(u)r was used in pcregrep, only the first matching substring in
32        each matching line was coloured. Now it goes on to look for further matches
33        of any of the test patterns, which is the same behaviour as GNU grep.
34    
35    7.  A pattern that could match an empty string could cause pcregrep to loop; it
36        doesn't make sense to accept an empty string match in pcregrep, so I have
37        locked it out (using PCRE's PCRE_NOTEMPTY option). By experiment, this
38        seems to be how GNU grep behaves.
39    
40    8.  The pattern (?(?=.*b)b|^) was incorrectly compiled as "match must be at
41        start or after a newline", because the conditional assertion was not being
42        correctly handled. The rule now is that both the assertion and what follows
43        in the first alternative must satisfy the test.
44    
45    9.  If auto-callout was enabled in a pattern with a conditional group whose
46        condition was an assertion, PCRE could crash during matching, both with
47        pcre_exec() and pcre_dfa_exec().
48    
49    10. The PCRE_DOLLAR_ENDONLY option was not working when pcre_dfa_exec() was
50        used for matching.
51    
52    11. Unicode property support in character classes was not working for
53        characters (bytes) greater than 127 when not in UTF-8 mode.
54    
55    12. Added the -M command line option to pcretest.
56    
57    14. Added the non-standard REG_NOTEMPTY option to the POSIX interface.
58    
59    15. Added the PCRE_NO_START_OPTIMIZE match-time option.
60    
61    16. Added comments and documentation about mis-use of no_arg in the C++
62        wrapper.
63    
64    17. Implemented support for UTF-8 encoding in EBCDIC environments, a patch
65        from Martin Jerabek that uses macro names for all relevant character and
66        string constants.
67    
68    18. Added to pcre_internal.h two configuration checks: (a) If both EBCDIC and
69        SUPPORT_UTF8 are set, give an error; (b) If SUPPORT_UCP is set without
70        SUPPORT_UTF8, define SUPPORT_UTF8. The "configure" script handles both of
71        these, but not everybody uses configure.
72    
73    19. A conditional group that had only one branch was not being correctly
74        recognized as an item that could match an empty string. This meant that an
75        enclosing group might also not be so recognized, causing infinite looping
76        (and probably a segfault) for patterns such as ^"((?(?=[a])[^"])|b)*"$
77        with the subject "ab", where knowledge that the repeated group can match
78        nothing is needed in order to break the loop.
79    
80    20. If a pattern that was compiled with callouts was matched using pcre_dfa_
81        exec(), but without supplying a callout function, matching went wrong.
82    
83    21. If PCRE_ERROR_MATCHLIMIT occurred during a recursion, there was a memory
84        leak if the size of the offset vector was greater than 30. When the vector
85        is smaller, the saved offsets during recursion go onto a local stack
86        vector, but for larger vectors malloc() is used. It was failing to free
87        when the recursion yielded PCRE_ERROR_MATCH_LIMIT (or any other "abnormal"
88        error, in fact).
89    
90    22. There was a missing #ifdef SUPPORT_UTF8 round one of the variables in the
91        heapframe that is used only when UTF-8 support is enabled. This caused no
92        problem, but was untidy.
93    
94    
95    Version 7.8 05-Sep-08
96    ---------------------
97    
98    1.  Replaced UCP searching code with optimized version as implemented for Ad
99        Muncher (http://www.admuncher.com/) by Peter Kankowski. This uses a two-
100        stage table and inline lookup instead of a function, giving speed ups of 2
101        to 5 times on some simple patterns that I tested. Permission was given to
102        distribute the MultiStage2.py script that generates the tables (it's not in
103        the tarball, but is in the Subversion repository).
104    
105    2.  Updated the Unicode datatables to Unicode 5.1.0. This adds yet more
106        scripts.
107    
108    3.  Change 12 for 7.7 introduced a bug in pcre_study() when a pattern contained
109        a group with a zero qualifier. The result of the study could be incorrect,
110        or the function might crash, depending on the pattern.
111    
112    4.  Caseless matching was not working for non-ASCII characters in back
113        references. For example, /(\x{de})\1/8i was not matching \x{de}\x{fe}.
114        It now works when Unicode Property Support is available.
115    
116    5.  In pcretest, an escape such as \x{de} in the data was always generating
117        a UTF-8 string, even in non-UTF-8 mode. Now it generates a single byte in
118        non-UTF-8 mode. If the value is greater than 255, it gives a warning about
119        truncation.
120    
121    6.  Minor bugfix in pcrecpp.cc (change "" == ... to NULL == ...).
122    
123    7.  Added two (int) casts to pcregrep when printing the difference of two
124        pointers, in case they are 64-bit values.
125    
126    8.  Added comments about Mac OS X stack usage to the pcrestack man page and to
127        test 2 if it fails.
128    
129    9.  Added PCRE_CALL_CONVENTION just before the names of all exported functions,
130        and a #define of that name to empty if it is not externally set. This is to
131        allow users of MSVC to set it if necessary.
132    
133    10. The PCRE_EXP_DEFN macro which precedes exported functions was missing from
134        the convenience functions in the pcre_get.c source file.
135    
136    11. An option change at the start of a pattern that had top-level alternatives
137        could cause overwriting and/or a crash. This command provoked a crash in
138        some environments:
139    
140          printf "/(?i)[\xc3\xa9\xc3\xbd]|[\xc3\xa9\xc3\xbdA]/8\n" | pcretest
141    
142        This potential security problem was recorded as CVE-2008-2371.
143    
144    12. For a pattern where the match had to start at the beginning or immediately
145        after a newline (e.g /.*anything/ without the DOTALL flag), pcre_exec() and
146        pcre_dfa_exec() could read past the end of the passed subject if there was
147        no match. To help with detecting such bugs (e.g. with valgrind), I modified
148        pcretest so that it places the subject at the end of its malloc-ed buffer.
149    
150    13. The change to pcretest in 12 above threw up a couple more cases when pcre_
151        exec() might read past the end of the data buffer in UTF-8 mode.
152    
153    14. A similar bug to 7.3/2 existed when the PCRE_FIRSTLINE option was set and
154        the data contained the byte 0x85 as part of a UTF-8 character within its
155        first line. This applied both to normal and DFA matching.
156    
157    15. Lazy qualifiers were not working in some cases in UTF-8 mode. For example,
158        /^[^d]*?$/8 failed to match "abc".
159    
160    16. Added a missing copyright notice to pcrecpp_internal.h.
161    
162    17. Make it more clear in the documentation that values returned from
163        pcre_exec() in ovector are byte offsets, not character counts.
164    
165    18. Tidied a few places to stop certain compilers from issuing warnings.
166    
167    19. Updated the Virtual Pascal + BCC files to compile the latest v7.7, as
168        supplied by Stefan Weber. I made a further small update for 7.8 because
169        there is a change of source arrangements: the pcre_searchfuncs.c module is
170        replaced by pcre_ucd.c.
171    
172    
173    Version 7.7 07-May-08
174    ---------------------
175    
176    1.  Applied Craig's patch to sort out a long long problem: "If we can't convert
177        a string to a long long, pretend we don't even have a long long." This is
178        done by checking for the strtoq, strtoll, and _strtoi64 functions.
179    
180    2.  Applied Craig's patch to pcrecpp.cc to restore ABI compatibility with
181        pre-7.6 versions, which defined a global no_arg variable instead of putting
182        it in the RE class. (See also #8 below.)
183    
184    3.  Remove a line of dead code, identified by coverity and reported by Nuno
185        Lopes.
186    
187    4.  Fixed two related pcregrep bugs involving -r with --include or --exclude:
188    
189        (1) The include/exclude patterns were being applied to the whole pathnames
190            of files, instead of just to the final components.
191    
192        (2) If there was more than one level of directory, the subdirectories were
193            skipped unless they satisfied the include/exclude conditions. This is
194            inconsistent with GNU grep (and could even be seen as contrary to the
195            pcregrep specification - which I improved to make it absolutely clear).
196            The action now is always to scan all levels of directory, and just
197            apply the include/exclude patterns to regular files.
198    
199    5.  Added the --include_dir and --exclude_dir patterns to pcregrep, and used
200        --exclude_dir in the tests to avoid scanning .svn directories.
201    
202    6.  Applied Craig's patch to the QuoteMeta function so that it escapes the
203        NUL character as backslash + 0 rather than backslash + NUL, because PCRE
204        doesn't support NULs in patterns.
205    
206    7.  Added some missing "const"s to declarations of static tables in
207        pcre_compile.c and pcre_dfa_exec.c.
208    
209    8.  Applied Craig's patch to pcrecpp.cc to fix a problem in OS X that was
210        caused by fix #2  above. (Subsequently also a second patch to fix the
211        first patch. And a third patch - this was a messy problem.)
212    
213    9.  Applied Craig's patch to remove the use of push_back().
214    
215    10. Applied Alan Lehotsky's patch to add REG_STARTEND support to the POSIX
216        matching function regexec().
217    
218    11. Added support for the Oniguruma syntax \g<name>, \g<n>, \g'name', \g'n',
219        which, however, unlike Perl's \g{...}, are subroutine calls, not back
220        references. PCRE supports relative numbers with this syntax (I don't think
221        Oniguruma does).
222    
223    12. Previously, a group with a zero repeat such as (...){0} was completely
224        omitted from the compiled regex. However, this means that if the group
225        was called as a subroutine from elsewhere in the pattern, things went wrong
226        (an internal error was given). Such groups are now left in the compiled
227        pattern, with a new opcode that causes them to be skipped at execution
228        time.
229    
230    13. Added the PCRE_JAVASCRIPT_COMPAT option. This makes the following changes
231        to the way PCRE behaves:
232    
233        (a) A lone ] character is dis-allowed (Perl treats it as data).
234    
235        (b) A back reference to an unmatched subpattern matches an empty string
236            (Perl fails the current match path).
237    
238        (c) A data ] in a character class must be notated as \] because if the
239            first data character in a class is ], it defines an empty class. (In
240            Perl it is not possible to have an empty class.) The empty class []
241            never matches; it forces failure and is equivalent to (*FAIL) or (?!).
242            The negative empty class [^] matches any one character, independently
243            of the DOTALL setting.
244    
245    14. A pattern such as /(?2)[]a()b](abc)/ which had a forward reference to a
246        non-existent subpattern following a character class starting with ']' and
247        containing () gave an internal compiling error instead of "reference to
248        non-existent subpattern". Fortunately, when the pattern did exist, the
249        compiled code was correct. (When scanning forwards to check for the
250        existencd of the subpattern, it was treating the data ']' as terminating
251        the class, so got the count wrong. When actually compiling, the reference
252        was subsequently set up correctly.)
253    
254    15. The "always fail" assertion (?!) is optimzed to (*FAIL) by pcre_compile;
255        it was being rejected as not supported by pcre_dfa_exec(), even though
256        other assertions are supported. I have made pcre_dfa_exec() support
257        (*FAIL).
258    
259    16. The implementation of 13c above involved the invention of a new opcode,
260        OP_ALLANY, which is like OP_ANY but doesn't check the /s flag. Since /s
261        cannot be changed at match time, I realized I could make a small
262        improvement to matching performance by compiling OP_ALLANY instead of
263        OP_ANY for "." when DOTALL was set, and then removing the runtime tests
264        on the OP_ANY path.
265    
266    17. Compiling pcretest on Windows with readline support failed without the
267        following two fixes: (1) Make the unistd.h include conditional on
268        HAVE_UNISTD_H; (2) #define isatty and fileno as _isatty and _fileno.
269    
270    18. Changed CMakeLists.txt and cmake/FindReadline.cmake to arrange for the
271        ncurses library to be included for pcretest when ReadLine support is
272        requested, but also to allow for it to be overridden. This patch came from
273        Daniel Bergström.
274    
275    19. There was a typo in the file ucpinternal.h where f0_rangeflag was defined
276        as 0x00f00000 instead of 0x00800000. Luckily, this would not have caused
277        any errors with the current Unicode tables. Thanks to Peter Kankowski for
278        spotting this.
279    
280    
281    Version 7.6 28-Jan-08
282    ---------------------
283    
284    1.  A character class containing a very large number of characters with
285        codepoints greater than 255 (in UTF-8 mode, of course) caused a buffer
286        overflow.
287    
288    2.  Patch to cut out the "long long" test in pcrecpp_unittest when
289        HAVE_LONG_LONG is not defined.
290    
291    3.  Applied Christian Ehrlicher's patch to update the CMake build files to
292        bring them up to date and include new features. This patch includes:
293    
294        - Fixed PH's badly added libz and libbz2 support.
295        - Fixed a problem with static linking.
296        - Added pcredemo. [But later removed - see 7 below.]
297        - Fixed dftables problem and added an option.
298        - Added a number of HAVE_XXX tests, including HAVE_WINDOWS_H and
299            HAVE_LONG_LONG.
300        - Added readline support for pcretest.
301        - Added an listing of the option settings after cmake has run.
302    
303    4.  A user submitted a patch to Makefile that makes it easy to create
304        "pcre.dll" under mingw when using Configure/Make. I added stuff to
305        Makefile.am that cause it to include this special target, without
306        affecting anything else. Note that the same mingw target plus all
307        the other distribution libraries and programs are now supported
308        when configuring with CMake (see 6 below) instead of with
309        Configure/Make.
310    
311    5.  Applied Craig's patch that moves no_arg into the RE class in the C++ code.
312        This is an attempt to solve the reported problem "pcrecpp::no_arg is not
313        exported in the Windows port". It has not yet been confirmed that the patch
314        solves the problem, but it does no harm.
315    
316    6.  Applied Sheri's patch to CMakeLists.txt to add NON_STANDARD_LIB_PREFIX and
317        NON_STANDARD_LIB_SUFFIX for dll names built with mingw when configured
318        with CMake, and also correct the comment about stack recursion.
319    
320    7.  Remove the automatic building of pcredemo from the ./configure system and
321        from CMakeLists.txt. The whole idea of pcredemo.c is that it is an example
322        of a program that users should build themselves after PCRE is installed, so
323        building it automatically is not really right. What is more, it gave
324        trouble in some build environments.
325    
326    8.  Further tidies to CMakeLists.txt from Sheri and Christian.
327    
328    
329    Version 7.5 10-Jan-08
330    ---------------------
331    
332    1.  Applied a patch from Craig: "This patch makes it possible to 'ignore'
333        values in parens when parsing an RE using the C++ wrapper."
334    
335    2.  Negative specials like \S did not work in character classes in UTF-8 mode.
336        Characters greater than 255 were excluded from the class instead of being
337        included.
338    
339    3.  The same bug as (2) above applied to negated POSIX classes such as
340        [:^space:].
341    
342    4.  PCRECPP_STATIC was referenced in pcrecpp_internal.h, but nowhere was it
343        defined or documented. It seems to have been a typo for PCRE_STATIC, so
344        I have changed it.
345    
346    5.  The construct (?&) was not diagnosed as a syntax error (it referenced the
347        first named subpattern) and a construct such as (?&a) would reference the
348        first named subpattern whose name started with "a" (in other words, the
349        length check was missing). Both these problems are fixed. "Subpattern name
350        expected" is now given for (?&) (a zero-length name), and this patch also
351        makes it give the same error for \k'' (previously it complained that that
352        was a reference to a non-existent subpattern).
353    
354    6.  The erroneous patterns (?+-a) and (?-+a) give different error messages;
355        this is right because (?- can be followed by option settings as well as by
356        digits. I have, however, made the messages clearer.
357    
358    7.  Patterns such as (?(1)a|b) (a pattern that contains fewer subpatterns
359        than the number used in the conditional) now cause a compile-time error.
360        This is actually not compatible with Perl, which accepts such patterns, but
361        treats the conditional as always being FALSE (as PCRE used to), but it
362        seems to me that giving a diagnostic is better.
363    
364    8.  Change "alphameric" to the more common word "alphanumeric" in comments
365        and messages.
366    
367    9.  Fix two occurrences of "backslash" in comments that should have been
368        "backspace".
369    
370    10. Remove two redundant lines of code that can never be obeyed (their function
371        was moved elsewhere).
372    
373    11. The program that makes PCRE's Unicode character property table had a bug
374        which caused it to generate incorrect table entries for sequences of
375        characters that have the same character type, but are in different scripts.
376        It amalgamated them into a single range, with the script of the first of
377        them. In other words, some characters were in the wrong script. There were
378        thirteen such cases, affecting characters in the following ranges:
379    
380          U+002b0 - U+002c1
381          U+0060c - U+0060d
382          U+0061e - U+00612
383          U+0064b - U+0065e
384          U+0074d - U+0076d
385          U+01800 - U+01805
386          U+01d00 - U+01d77
387          U+01d9b - U+01dbf
388          U+0200b - U+0200f
389          U+030fc - U+030fe
390          U+03260 - U+0327f
391          U+0fb46 - U+0fbb1
392          U+10450 - U+1049d
393    
394    12. The -o option (show only the matching part of a line) for pcregrep was not
395        compatible with GNU grep in that, if there was more than one match in a
396        line, it showed only the first of them. It now behaves in the same way as
397        GNU grep.
398    
399    13. If the -o and -v options were combined for pcregrep, it printed a blank
400        line for every non-matching line. GNU grep prints nothing, and pcregrep now
401        does the same. The return code can be used to tell if there were any
402        non-matching lines.
403    
404    14. Added --file-offsets and --line-offsets to pcregrep.
405    
406    15. The pattern (?=something)(?R) was not being diagnosed as a potentially
407        infinitely looping recursion. The bug was that positive lookaheads were not
408        being skipped when checking for a possible empty match (negative lookaheads
409        and both kinds of lookbehind were skipped).
410    
411    16. Fixed two typos in the Windows-only code in pcregrep.c, and moved the
412        inclusion of <windows.h> to before rather than after the definition of
413        INVALID_FILE_ATTRIBUTES (patch from David Byron).
414    
415    17. Specifying a possessive quantifier with a specific limit for a Unicode
416        character property caused pcre_compile() to compile bad code, which led at
417        runtime to PCRE_ERROR_INTERNAL (-14). Examples of patterns that caused this
418        are: /\p{Zl}{2,3}+/8 and /\p{Cc}{2}+/8. It was the possessive "+" that
419        caused the error; without that there was no problem.
420    
421    18. Added --enable-pcregrep-libz and --enable-pcregrep-libbz2.
422    
423    19. Added --enable-pcretest-libreadline.
424    
425    20. In pcrecpp.cc, the variable 'count' was incremented twice in
426        RE::GlobalReplace(). As a result, the number of replacements returned was
427        double what it should be. I removed one of the increments, but Craig sent a
428        later patch that removed the other one (the right fix) and added unit tests
429        that check the return values (which was not done before).
430    
431    21. Several CMake things:
432    
433        (1) Arranged that, when cmake is used on Unix, the libraries end up with
434            the names libpcre and libpcreposix, not just pcre and pcreposix.
435    
436        (2) The above change means that pcretest and pcregrep are now correctly
437            linked with the newly-built libraries, not previously installed ones.
438    
439        (3) Added PCRE_SUPPORT_LIBREADLINE, PCRE_SUPPORT_LIBZ, PCRE_SUPPORT_LIBBZ2.
440    
441    22. In UTF-8 mode, with newline set to "any", a pattern such as .*a.*=.b.*
442        crashed when matching a string such as a\x{2029}b (note that \x{2029} is a
443        UTF-8 newline character). The key issue is that the pattern starts .*;
444        this means that the match must be either at the beginning, or after a
445        newline. The bug was in the code for advancing after a failed match and
446        checking that the new position followed a newline. It was not taking
447        account of UTF-8 characters correctly.
448    
449    23. PCRE was behaving differently from Perl in the way it recognized POSIX
450        character classes. PCRE was not treating the sequence [:...:] as a
451        character class unless the ... were all letters. Perl, however, seems to
452        allow any characters between [: and :], though of course it rejects as
453        unknown any "names" that contain non-letters, because all the known class
454        names consist only of letters. Thus, Perl gives an error for [[:1234:]],
455        for example, whereas PCRE did not - it did not recognize a POSIX character
456        class. This seemed a bit dangerous, so the code has been changed to be
457        closer to Perl. The behaviour is not identical to Perl, because PCRE will
458        diagnose an unknown class for, for example, [[:l\ower:]] where Perl will
459        treat it as [[:lower:]]. However, PCRE does now give "unknown" errors where
460        Perl does, and where it didn't before.
461    
462    24. Rewrite so as to remove the single use of %n from pcregrep because in some
463        Windows environments %n is disabled by default.
464    
465    
466    Version 7.4 21-Sep-07
467    ---------------------
468    
469    1.  Change 7.3/28 was implemented for classes by looking at the bitmap. This
470        means that a class such as [\s] counted as "explicit reference to CR or
471        LF". That isn't really right - the whole point of the change was to try to
472        help when there was an actual mention of one of the two characters. So now
473        the change happens only if \r or \n (or a literal CR or LF) character is
474        encountered.
475    
476    2.  The 32-bit options word was also used for 6 internal flags, but the numbers
477        of both had grown to the point where there were only 3 bits left.
478        Fortunately, there was spare space in the data structure, and so I have
479        moved the internal flags into a new 16-bit field to free up more option
480        bits.
481    
482    3.  The appearance of (?J) at the start of a pattern set the DUPNAMES option,
483        but did not set the internal JCHANGED flag - either of these is enough to
484        control the way the "get" function works - but the PCRE_INFO_JCHANGED
485        facility is supposed to tell if (?J) was ever used, so now (?J) at the
486        start sets both bits.
487    
488    4.  Added options (at build time, compile time, exec time) to change \R from
489        matching any Unicode line ending sequence to just matching CR, LF, or CRLF.
490    
491    5.  doc/pcresyntax.html was missing from the distribution.
492    
493    6.  Put back the definition of PCRE_ERROR_NULLWSLIMIT, for backward
494        compatibility, even though it is no longer used.
495    
496    7.  Added macro for snprintf to pcrecpp_unittest.cc and also for strtoll and
497        strtoull to pcrecpp.cc to select the available functions in WIN32 when the
498        windows.h file is present (where different names are used). [This was
499        reversed later after testing - see 16 below.]
500    
501    8.  Changed all #include <config.h> to #include "config.h". There were also
502        some further <pcre.h> cases that I changed to "pcre.h".
503    
504    9.  When pcregrep was used with the --colour option, it missed the line ending
505        sequence off the lines that it output.
506    
507    10. It was pointed out to me that arrays of string pointers cause lots of
508        relocations when a shared library is dynamically loaded. A technique of
509        using a single long string with a table of offsets can drastically reduce
510        these. I have refactored PCRE in four places to do this. The result is
511        dramatic:
512    
513          Originally:                          290
514          After changing UCP table:            187
515          After changing error message table:   43
516          After changing table of "verbs"       36
517          After changing table of Posix names   22
518    
519        Thanks to the folks working on Gregex for glib for this insight.
520    
521    11. --disable-stack-for-recursion caused compiling to fail unless -enable-
522        unicode-properties was also set.
523    
524    12. Updated the tests so that they work when \R is defaulted to ANYCRLF.
525    
526    13. Added checks for ANY and ANYCRLF to pcrecpp.cc where it previously
527        checked only for CRLF.
528    
529    14. Added casts to pcretest.c to avoid compiler warnings.
530    
531    15. Added Craig's patch to various pcrecpp modules to avoid compiler warnings.
532    
533    16. Added Craig's patch to remove the WINDOWS_H tests, that were not working,
534        and instead check for _strtoi64 explicitly, and avoid the use of snprintf()
535        entirely. This removes changes made in 7 above.
536    
537    17. The CMake files have been updated, and there is now more information about
538        building with CMake in the NON-UNIX-USE document.
539    
540    
541    Version 7.3 28-Aug-07
542    ---------------------
543    
544     1. In the rejigging of the build system that eventually resulted in 7.1, the
545        line "#include <pcre.h>" was included in pcre_internal.h. The use of angle
546        brackets there is not right, since it causes compilers to look for an
547        installed pcre.h, not the version that is in the source that is being
548        compiled (which of course may be different). I have changed it back to:
549    
550          #include "pcre.h"
551    
552        I have a vague recollection that the change was concerned with compiling in
553        different directories, but in the new build system, that is taken care of
554        by the VPATH setting the Makefile.
555    
556     2. The pattern .*$ when run in not-DOTALL UTF-8 mode with newline=any failed
557        when the subject happened to end in the byte 0x85 (e.g. if the last
558        character was \x{1ec5}). *Character* 0x85 is one of the "any" newline
559        characters but of course it shouldn't be taken as a newline when it is part
560        of another character. The bug was that, for an unlimited repeat of . in
561        not-DOTALL UTF-8 mode, PCRE was advancing by bytes rather than by
562        characters when looking for a newline.
563    
564     3. A small performance improvement in the DOTALL UTF-8 mode .* case.
565    
566     4. Debugging: adjusted the names of opcodes for different kinds of parentheses
567        in debug output.
568    
569     5. Arrange to use "%I64d" instead of "%lld" and "%I64u" instead of "%llu" for
570        long printing in the pcrecpp unittest when running under MinGW.
571    
572     6. ESC_K was left out of the EBCDIC table.
573    
574     7. Change 7.0/38 introduced a new limit on the number of nested non-capturing
575        parentheses; I made it 1000, which seemed large enough. Unfortunately, the
576        limit also applies to "virtual nesting" when a pattern is recursive, and in
577        this case 1000 isn't so big. I have been able to remove this limit at the
578        expense of backing off one optimization in certain circumstances. Normally,
579        when pcre_exec() would call its internal match() function recursively and
580        immediately return the result unconditionally, it uses a "tail recursion"
581        feature to save stack. However, when a subpattern that can match an empty
582        string has an unlimited repetition quantifier, it no longer makes this
583        optimization. That gives it a stack frame in which to save the data for
584        checking that an empty string has been matched. Previously this was taken
585        from the 1000-entry workspace that had been reserved. So now there is no
586        explicit limit, but more stack is used.
587    
588     8. Applied Daniel's patches to solve problems with the import/export magic
589        syntax that is required for Windows, and which was going wrong for the
590        pcreposix and pcrecpp parts of the library. These were overlooked when this
591        problem was solved for the main library.
592    
593     9. There were some crude static tests to avoid integer overflow when computing
594        the size of patterns that contain repeated groups with explicit upper
595        limits. As the maximum quantifier is 65535, the maximum group length was
596        set at 30,000 so that the product of these two numbers did not overflow a
597        32-bit integer. However, it turns out that people want to use groups that
598        are longer than 30,000 bytes (though not repeat them that many times).
599        Change 7.0/17 (the refactoring of the way the pattern size is computed) has
600        made it possible to implement the integer overflow checks in a much more
601        dynamic way, which I have now done. The artificial limitation on group
602        length has been removed - we now have only the limit on the total length of
603        the compiled pattern, which depends on the LINK_SIZE setting.
604    
605    10. Fixed a bug in the documentation for get/copy named substring when
606        duplicate names are permitted. If none of the named substrings are set, the
607        functions return PCRE_ERROR_NOSUBSTRING (7); the doc said they returned an
608        empty string.
609    
610    11. Because Perl interprets \Q...\E at a high level, and ignores orphan \E
611        instances, patterns such as [\Q\E] or [\E] or even [^\E] cause an error,
612        because the ] is interpreted as the first data character and the
613        terminating ] is not found. PCRE has been made compatible with Perl in this
614        regard. Previously, it interpreted [\Q\E] as an empty class, and [\E] could
615        cause memory overwriting.
616    
617    10. Like Perl, PCRE automatically breaks an unlimited repeat after an empty
618        string has been matched (to stop an infinite loop). It was not recognizing
619        a conditional subpattern that could match an empty string if that
620        subpattern was within another subpattern. For example, it looped when
621        trying to match  (((?(1)X|))*)  but it was OK with  ((?(1)X|)*)  where the
622        condition was not nested. This bug has been fixed.
623    
624    12. A pattern like \X?\d or \P{L}?\d in non-UTF-8 mode could cause a backtrack
625        past the start of the subject in the presence of bytes with the top bit
626        set, for example "\x8aBCD".
627    
628    13. Added Perl 5.10 experimental backtracking controls (*FAIL), (*F), (*PRUNE),
629        (*SKIP), (*THEN), (*COMMIT), and (*ACCEPT).
630    
631    14. Optimized (?!) to (*FAIL).
632    
633    15. Updated the test for a valid UTF-8 string to conform to the later RFC 3629.
634        This restricts code points to be within the range 0 to 0x10FFFF, excluding
635        the "low surrogate" sequence 0xD800 to 0xDFFF. Previously, PCRE allowed the
636        full range 0 to 0x7FFFFFFF, as defined by RFC 2279. Internally, it still
637        does: it's just the validity check that is more restrictive.
638    
639    16. Inserted checks for integer overflows during escape sequence (backslash)
640        processing, and also fixed erroneous offset values for syntax errors during
641        backslash processing.
642    
643    17. Fixed another case of looking too far back in non-UTF-8 mode (cf 12 above)
644        for patterns like [\PPP\x8a]{1,}\x80 with the subject "A\x80".
645    
646    18. An unterminated class in a pattern like (?1)\c[ with a "forward reference"
647        caused an overrun.
648    
649    19. A pattern like (?:[\PPa*]*){8,} which had an "extended class" (one with
650        something other than just ASCII characters) inside a group that had an
651        unlimited repeat caused a loop at compile time (while checking to see
652        whether the group could match an empty string).
653    
654    20. Debugging a pattern containing \p or \P could cause a crash. For example,
655        [\P{Any}] did so. (Error in the code for printing property names.)
656    
657    21. An orphan \E inside a character class could cause a crash.
658    
659    22. A repeated capturing bracket such as (A)? could cause a wild memory
660        reference during compilation.
661    
662    23. There are several functions in pcre_compile() that scan along a compiled
663        expression for various reasons (e.g. to see if it's fixed length for look
664        behind). There were bugs in these functions when a repeated \p or \P was
665        present in the pattern. These operators have additional parameters compared
666        with \d, etc, and these were not being taken into account when moving along
667        the compiled data. Specifically:
668    
669        (a) A item such as \p{Yi}{3} in a lookbehind was not treated as fixed
670            length.
671    
672        (b) An item such as \pL+ within a repeated group could cause crashes or
673            loops.
674    
675        (c) A pattern such as \p{Yi}+(\P{Yi}+)(?1) could give an incorrect
676            "reference to non-existent subpattern" error.
677    
678        (d) A pattern like (\P{Yi}{2}\277)? could loop at compile time.
679    
680    24. A repeated \S or \W in UTF-8 mode could give wrong answers when multibyte
681        characters were involved (for example /\S{2}/8g with "A\x{a3}BC").
682    
683    25. Using pcregrep in multiline, inverted mode (-Mv) caused it to loop.
684    
685    26. Patterns such as [\P{Yi}A] which include \p or \P and just one other
686        character were causing crashes (broken optimization).
687    
688    27. Patterns such as (\P{Yi}*\277)* (group with possible zero repeat containing
689        \p or \P) caused a compile-time loop.
690    
691    28. More problems have arisen in unanchored patterns when CRLF is a valid line
692        break. For example, the unstudied pattern [\r\n]A does not match the string
693        "\r\nA" because change 7.0/46 below moves the current point on by two
694        characters after failing to match at the start. However, the pattern \nA
695        *does* match, because it doesn't start till \n, and if [\r\n]A is studied,
696        the same is true. There doesn't seem any very clean way out of this, but
697        what I have chosen to do makes the common cases work: PCRE now takes note
698        of whether there can be an explicit match for \r or \n anywhere in the
699        pattern, and if so, 7.0/46 no longer applies. As part of this change,
700        there's a new PCRE_INFO_HASCRORLF option for finding out whether a compiled
701        pattern has explicit CR or LF references.
702    
703    29. Added (*CR) etc for changing newline setting at start of pattern.
704    
705    
706    Version 7.2 19-Jun-07
707    ---------------------
708    
709     1. If the fr_FR locale cannot be found for test 3, try the "french" locale,
710        which is apparently normally available under Windows.
711    
712     2. Re-jig the pcregrep tests with different newline settings in an attempt
713        to make them independent of the local environment's newline setting.
714    
715     3. Add code to configure.ac to remove -g from the CFLAGS default settings.
716    
717     4. Some of the "internals" tests were previously cut out when the link size
718        was not 2, because the output contained actual offsets. The recent new
719        "Z" feature of pcretest means that these can be cut out, making the tests
720        usable with all link sizes.
721    
722     5. Implemented Stan Switzer's goto replacement for longjmp() when not using
723        stack recursion. This gives a massive performance boost under BSD, but just
724        a small improvement under Linux. However, it saves one field in the frame
725        in all cases.
726    
727     6. Added more features from the forthcoming Perl 5.10:
728    
729        (a) (?-n) (where n is a string of digits) is a relative subroutine or
730            recursion call. It refers to the nth most recently opened parentheses.
731    
732        (b) (?+n) is also a relative subroutine call; it refers to the nth next
733            to be opened parentheses.
734    
735        (c) Conditions that refer to capturing parentheses can be specified
736            relatively, for example, (?(-2)... or (?(+3)...
737    
738        (d) \K resets the start of the current match so that everything before
739            is not part of it.
740    
741        (e) \k{name} is synonymous with \k<name> and \k'name' (.NET compatible).
742    
743        (f) \g{name} is another synonym - part of Perl 5.10's unification of
744            reference syntax.
745    
746        (g) (?| introduces a group in which the numbering of parentheses in each
747            alternative starts with the same number.
748    
749        (h) \h, \H, \v, and \V match horizontal and vertical whitespace.
750    
751     7. Added two new calls to pcre_fullinfo(): PCRE_INFO_OKPARTIAL and
752        PCRE_INFO_JCHANGED.
753    
754     8. A pattern such as  (.*(.)?)*  caused pcre_exec() to fail by either not
755        terminating or by crashing. Diagnosed by Viktor Griph; it was in the code
756        for detecting groups that can match an empty string.
757    
758     9. A pattern with a very large number of alternatives (more than several
759        hundred) was running out of internal workspace during the pre-compile
760        phase, where pcre_compile() figures out how much memory will be needed. A
761        bit of new cunning has reduced the workspace needed for groups with
762        alternatives. The 1000-alternative test pattern now uses 12 bytes of
763        workspace instead of running out of the 4096 that are available.
764    
765    10. Inserted some missing (unsigned int) casts to get rid of compiler warnings.
766    
767    11. Applied patch from Google to remove an optimization that didn't quite work.
768        The report of the bug said:
769    
770          pcrecpp::RE("a*").FullMatch("aaa") matches, while
771          pcrecpp::RE("a*?").FullMatch("aaa") does not, and
772          pcrecpp::RE("a*?\\z").FullMatch("aaa") does again.
773    
774    12. If \p or \P was used in non-UTF-8 mode on a character greater than 127
775        it matched the wrong number of bytes.
776    
777    
778    Version 7.1 24-Apr-07
779    ---------------------
780    
781     1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
782        that is more "standard", making use of automake and other Autotools. There
783        is some re-arrangement of the files and adjustment of comments consequent
784        on this.
785    
786     2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
787        for recursive directory scanning broke on some systems because the files
788        are not scanned in any specific order and on different systems the order
789        was different. A call to "sort" has been inserted into RunGrepTest for the
790        approprate test as a short-term fix. In the longer term there may be an
791        alternative.
792    
793     3. I had an email from Eric Raymond about problems translating some of PCRE's
794        man pages to HTML (despite the fact that I distribute HTML pages, some
795        people do their own conversions for various reasons). The problems
796        concerned the use of low-level troff macros .br and .in. I have therefore
797        removed all such uses from the man pages (some were redundant, some could
798        be replaced by .nf/.fi pairs). The 132html script that I use to generate
799        HTML has been updated to handle .nf/.fi and to complain if it encounters
800        .br or .in.
801    
802     4. Updated comments in configure.ac that get placed in config.h.in and also
803        arranged for config.h to be included in the distribution, with the name
804        config.h.generic, for the benefit of those who have to compile without
805        Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
806    
807     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
808        Weber: (1) pcre_internal.h was missing some function renames; (2) updated
809        makevp.bat for the current PCRE, using the additional files
810        makevp_c.txt, makevp_l.txt, and pcregexp.pas.
811    
812     6. A Windows user reported a minor discrepancy with test 2, which turned out
813        to be caused by a trailing space on an input line that had got lost in his
814        copy. The trailing space was an accident, so I've just removed it.
815    
816     7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
817        that is needed.
818    
819     8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
820        as "const" (a) because they are and (b) because it helps the PHP
821        maintainers who have recently made a script to detect big data structures
822        in the php code that should be moved to the .rodata section. I remembered
823        to update Builducptable as well, so it won't revert if ucptable.h is ever
824        re-created.
825    
826     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
827        pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
828        order to be able to cut out the UTF-8 tables in the latter when UTF-8
829        support is not required. This saves 1.5-2K of code, which is important in
830        some applications.
831    
832        Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
833        so as not to refer to the tables, even though these functions will never be
834        called when UTF-8 support is disabled. Otherwise there are problems with a
835        shared library.
836    
837    10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
838    
839        (a) It was defining its arguments as char * instead of void *.
840    
841        (b) It was assuming that all moves were upwards in memory; this was true
842            a long time ago when I wrote it, but is no longer the case.
843    
844        The emulated memove() is provided for those environments that have neither
845        memmove() nor bcopy(). I didn't think anyone used it these days, but that
846        is clearly not the case, as these two bugs were recently reported.
847    
848    11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
849        and Detrail to create the HTML documentation, the .txt form of the man
850        pages, and it removes trailing spaces from listed files. It also creates
851        pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
852        case, it wraps all the #defines with #ifndefs. This script should be run
853        before "make dist".
854    
855    12. Fixed two fairly obscure bugs concerned with quantified caseless matching
856        with Unicode property support.
857    
858        (a) For a maximizing quantifier, if the two different cases of the
859            character were of different lengths in their UTF-8 codings (there are
860            some cases like this - I found 11), and the matching function had to
861            back up over a mixture of the two cases, it incorrectly assumed they
862            were both the same length.
863    
864        (b) When PCRE was configured to use the heap rather than the stack for
865            recursion during matching, it was not correctly preserving the data for
866            the other case of a UTF-8 character when checking ahead for a match
867            while processing a minimizing repeat. If the check also involved
868            matching a wide character, but failed, corruption could cause an
869            erroneous result when trying to check for a repeat of the original
870            character.
871    
872    13. Some tidying changes to the testing mechanism:
873    
874        (a) The RunTest script now detects the internal link size and whether there
875            is UTF-8 and UCP support by running ./pcretest -C instead of relying on
876            values substituted by "configure". (The RunGrepTest script already did
877            this for UTF-8.) The configure.ac script no longer substitutes the
878            relevant variables.
879    
880        (b) The debugging options /B and /D in pcretest show the compiled bytecode
881            with length and offset values. This means that the output is different
882            for different internal link sizes. Test 2 is skipped for link sizes
883            other than 2 because of this, bypassing the problem. Unfortunately,
884            there was also a test in test 3 (the locale tests) that used /B and
885            failed for link sizes other than 2. Rather than cut the whole test out,
886            I have added a new /Z option to pcretest that replaces the length and
887            offset values with spaces. This is now used to make test 3 independent
888            of link size. (Test 2 will be tidied up later.)
889    
890    14. If erroroffset was passed as NULL to pcre_compile, it provoked a
891        segmentation fault instead of returning the appropriate error message.
892    
893    15. In multiline mode when the newline sequence was set to "any", the pattern
894        ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
895        This doesn't seem right; it now treats the CRLF combination as the line
896        ending, and so does not match in that case. It's only a pattern such as ^$
897        that would hit this one: something like ^ABC$ would have failed after \r
898        and then tried again after \r\n.
899    
900    16. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
901        in an attempt to make files that differ only in their line terminators
902        compare equal. This works on Linux.
903    
904    17. Under certain error circumstances pcregrep might try to free random memory
905        as it exited. This is now fixed, thanks to valgrind.
906    
907    19. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
908        "abc\r\n\r\n", it found an unwanted second match after the second \r. This
909        was because its rules for how to advance for /g after matching an empty
910        string at the end of a line did not allow for this case. They now check for
911        it specially.
912    
913    20. pcretest is supposed to handle patterns and data of any length, by
914        extending its buffers when necessary. It was getting this wrong when the
915        buffer for a data line had to be extended.
916    
917    21. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or
918        CRLF as a newline sequence.
919    
920    22. Code for handling Unicode properties in pcre_dfa_exec() wasn't being cut
921        out by #ifdef SUPPORT_UCP. This did no harm, as it could never be used, but
922        I have nevertheless tidied it up.
923    
924    23. Added some casts to kill warnings from HP-UX ia64 compiler.
925    
926    24. Added a man page for pcre-config.
927    
928    
929    Version 7.0 19-Dec-06
930    ---------------------
931    
932     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
933        moving to gcc 4.1.1.
934    
935     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
936        sys/time.h, which is documented as needed for this function. It doesn't
937        seem to matter on Linux, but it showed up on some releases of OS X.
938    
939     3. It seems that there are systems where bytes whose values are greater than
940        127 match isprint() in the "C" locale. The "C" locale should be the
941        default when a C program starts up. In most systems, only ASCII printing
942        characters match isprint(). This difference caused the output from pcretest
943        to vary, making some of the tests fail. I have changed pcretest so that:
944    
945        (a) When it is outputting text in the compiled version of a pattern, bytes
946            other than 32-126 are always shown as hex escapes.
947    
948        (b) When it is outputting text that is a matched part of a subject string,
949            it does the same, unless a different locale has been set for the match
950            (using the /L modifier). In this case, it uses isprint() to decide.
951    
952     4. Fixed a major bug that caused incorrect computation of the amount of memory
953        required for a compiled pattern when options that changed within the
954        pattern affected the logic of the preliminary scan that determines the
955        length. The relevant options are -x, and -i in UTF-8 mode. The result was
956        that the computed length was too small. The symptoms of this bug were
957        either the PCRE error "internal error: code overflow" from pcre_compile(),
958        or a glibc crash with a message such as "pcretest: free(): invalid next
959        size (fast)". Examples of patterns that provoked this bug (shown in
960        pcretest format) are:
961    
962          /(?-x: )/x
963          /(?x)(?-x: \s*#\s*)/
964          /((?i)[\x{c0}])/8
965          /(?i:[\x{c0}])/8
966    
967        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
968        is now done differently.
969    
970     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
971        wrapper classes; (b) implement a new function in the C++ scanner that is
972        more efficient than the old way of doing things because it avoids levels of
973        recursion in the regex matching; (c) add a paragraph to the documentation
974        for the FullMatch() function.
975    
976     6. The escape sequence \n was being treated as whatever was defined as
977        "newline". Not only was this contrary to the documentation, which states
978        that \n is character 10 (hex 0A), but it also went horribly wrong when
979        "newline" was defined as CRLF. This has been fixed.
980    
981     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
982        was being set to -1 for the "end of line" case (supposedly a value that no
983        character can have). Though this value is never used (the check for end of
984        line is "zero bytes in current character"), it caused compiler complaints.
985        I've changed it to 0xffffffff.
986    
987     8. In pcre_version.c, the version string was being built by a sequence of
988        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
989        string (as it is for production releases) called a macro with an empty
990        argument. The C standard says the result of this is undefined. The gcc
991        compiler treats it as an empty string (which was what was wanted) but it is
992        reported that Visual C gives an error. The source has been hacked around to
993        avoid this problem.
994    
995     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
996        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
997        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
998        of them did).
999    
1000    10. Originally, pcretest opened its input and output without "b"; then I was
1001        told that "b" was needed in some environments, so it was added for release
1002        5.0 to both the input and output. (It makes no difference on Unix-like
1003        systems.) Later I was told that it is wrong for the input on Windows. I've
1004        now abstracted the modes into two macros, to make it easier to fiddle with
1005        them, and removed "b" from the input mode under Windows.
1006    
1007    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
1008    
1009    12. Added -help and --help to pcretest as an official way of being reminded
1010        of the options.
1011    
1012    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
1013        and pcrecpp.cc because they annoy compilers at high warning levels.
1014    
1015    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
1016    
1017    15. Fixed an occurrence of == in configure.ac that should have been = (shell
1018        scripts are not C programs :-) and which was not noticed because it works
1019        on Linux.
1020    
1021    16. pcretest is supposed to handle any length of pattern and data line (as one
1022        line or as a continued sequence of lines) by extending its input buffer if
1023        necessary. This feature was broken for very long pattern lines, leading to
1024        a string of junk being passed to pcre_compile() if the pattern was longer
1025        than about 50K.
1026    
1027    17. I have done a major re-factoring of the way pcre_compile() computes the
1028        amount of memory needed for a compiled pattern. Previously, there was code
1029        that made a preliminary scan of the pattern in order to do this. That was
1030        OK when PCRE was new, but as the facilities have expanded, it has become
1031        harder and harder to keep it in step with the real compile phase, and there
1032        have been a number of bugs (see for example, 4 above). I have now found a
1033        cunning way of running the real compile function in a "fake" mode that
1034        enables it to compute how much memory it would need, while actually only
1035        ever using a few hundred bytes of working memory and without too many
1036        tests of the mode. This should make future maintenance and development
1037        easier. A side effect of this work is that the limit of 200 on the nesting
1038        depth of parentheses has been removed (though this was never a serious
1039        limitation, I suspect). However, there is a downside: pcre_compile() now
1040        runs more slowly than before (30% or more, depending on the pattern). I
1041        hope this isn't a big issue. There is no effect on runtime performance.
1042    
1043    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
1044        newline (only possible for the last line of a file) and it was a
1045        pattern that set a locale (followed by /Lsomething), pcretest crashed.
1046    
1047    19. Added additional timing features to pcretest. (1) The -tm option now times
1048        matching only, not compiling. (2) Both -t and -tm can be followed, as a
1049        separate command line item, by a number that specifies the number of
1050        repeats to use when timing. The default is 50000; this gives better
1051        precision, but takes uncomfortably long for very large patterns.
1052    
1053    20. Extended pcre_study() to be more clever in cases where a branch of a
1054        subpattern has no definite first character. For example, (a*|b*)[cd] would
1055        previously give no result from pcre_study(). Now it recognizes that the
1056        first character must be a, b, c, or d.
1057    
1058    21. There was an incorrect error "recursive call could loop indefinitely" if
1059        a subpattern (or the entire pattern) that was being tested for matching an
1060        empty string contained only one non-empty item after a nested subpattern.
1061        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
1062        incorrectly, because the \d was being skipped in the check.
1063    
1064    22. The pcretest program now has a new pattern option /B and a command line
1065        option -b, which is equivalent to adding /B to every pattern. This causes
1066        it to show the compiled bytecode, without the additional information that
1067        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
1068        is the same as /B/I).
1069    
1070    23. A new optimization is now able automatically to treat some sequences such
1071        as a*b as a*+b. More specifically, if something simple (such as a character
1072        or a simple class like \d) has an unlimited quantifier, and is followed by
1073        something that cannot possibly match the quantified thing, the quantifier
1074        is automatically "possessified".
1075    
1076    24. A recursive reference to a subpattern whose number was greater than 39
1077        went wrong under certain circumstances in UTF-8 mode. This bug could also
1078        have affected the operation of pcre_study().
1079    
1080    25. Realized that a little bit of performance could be had by replacing
1081        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
1082    
1083    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
1084    
1085    27. Possessive quantifiers such as a++ were previously implemented by turning
1086        them into atomic groups such as ($>a+). Now they have their own opcodes,
1087        which improves performance. This includes the automatically created ones
1088        from 23 above.
1089    
1090    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
1091        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
1092        the first matched character to be a colon. This applied both to named and
1093        numbered groups.
1094    
1095    29. The ucpinternal.h header file was missing its idempotency #ifdef.
1096    
1097    30. I was sent a "project" file called libpcre.a.dev which I understand makes
1098        building PCRE on Windows easier, so I have included it in the distribution.
1099    
1100    31. There is now a check in pcretest against a ridiculously large number being
1101        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
1102        loop, the loop is abandoned.
1103    
1104    32. Forward references to subpatterns in conditions such as (?(2)...) where
1105        subpattern 2 is defined later cause pcre_compile() to search forwards in
1106        the pattern for the relevant set of parentheses. This search went wrong
1107        when there were unescaped parentheses in a character class, parentheses
1108        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
1109    
1110    33. "Subroutine" calls and backreferences were previously restricted to
1111        referencing subpatterns earlier in the regex. This restriction has now
1112        been removed.
1113    
1114    34. Added a number of extra features that are going to be in Perl 5.10. On the
1115        whole, these are just syntactic alternatives for features that PCRE had
1116        previously implemented using the Python syntax or my own invention. The
1117        other formats are all retained for compatibility.
1118    
1119        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
1120            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
1121            also .NET compatible.
1122    
1123        (b) A recursion or subroutine call to a named group can now be defined as
1124            (?&name) as well as (?P>name).
1125    
1126        (c) A backreference to a named group can now be defined as \k<name> or
1127            \k'name' as well as (?P=name). The new forms, as well as being in Perl
1128            5.10, are also .NET compatible.
1129    
1130        (d) A conditional reference to a named group can now use the syntax
1131            (?(<name>) or (?('name') as well as (?(name).
1132    
1133        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
1134            groups (named and numbered) that are never evaluated inline, but can be
1135            called as "subroutines" from elsewhere. In effect, the DEFINE condition
1136            is always false. There may be only one alternative in such a group.
1137    
1138        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
1139            as the simple (?(R). The condition is true only if the most recent
1140            recursion is that of the given number or name. It does not search out
1141            through the entire recursion stack.
1142    
1143        (g) The escape \gN or \g{N} has been added, where N is a positive or
1144            negative number, specifying an absolute or relative reference.
1145    
1146    35. Tidied to get rid of some further signed/unsigned compiler warnings and
1147        some "unreachable code" warnings.
1148    
1149    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
1150        things, this adds five new scripts.
1151    
1152    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
1153        There were also incompatibilities regarding the handling of \Q..\E inside
1154        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
1155        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
1156    
1157    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
1158        matches an empty string, and forcibly breaks the loop. There were bugs in
1159        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
1160        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
1161        separate and independent bugs (that affected different cases) have been
1162        fixed.
1163    
1164    39. Refactored the code to abolish the use of different opcodes for small
1165        capturing bracket numbers. This is a tidy that I avoided doing when I
1166        removed the limit on the number of capturing brackets for 3.5 back in 2001.
1167        The new approach is not only tidier, it makes it possible to reduce the
1168        memory needed to fix the previous bug (38).
1169    
1170    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
1171        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
1172        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
1173        mode.
1174    
1175    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
1176        report.
1177    
1178    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
1179        copy construction and assignment in the C++ wrapper.
1180    
1181    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
1182        couple of bugs that could have given wrong results in the "--newline=crlf"
1183        case.
1184    
1185    44. Added a number of casts and did some reorganization of signed/unsigned int
1186        variables following suggestions from Dair Grant. Also renamed the variable
1187        "this" as "item" because it is a C++ keyword.
1188    
1189    45. Arranged for dftables to add
1190    
1191          #include "pcre_internal.h"
1192    
1193        to pcre_chartables.c because without it, gcc 4.x may remove the array
1194        definition from the final binary if PCRE is built into a static library and
1195        dead code stripping is activated.
1196    
1197    46. For an unanchored pattern, if a match attempt fails at the start of a
1198        newline sequence, and the newline setting is CRLF or ANY, and the next two
1199        characters are CRLF, advance by two characters instead of one.
1200    
1201    
1202    Version 6.7 04-Jul-06
1203    ---------------------
1204    
1205     1. In order to handle tests when input lines are enormously long, pcretest has
1206        been re-factored so that it automatically extends its buffers when
1207        necessary. The code is crude, but this _is_ just a test program. The
1208        default size has been increased from 32K to 50K.
1209    
1210     2. The code in pcre_study() was using the value of the re argument before
1211        testing it for NULL. (Of course, in any sensible call of the function, it
1212        won't be NULL.)
1213    
1214     3. The memmove() emulation function in pcre_internal.h, which is used on
1215        systems that lack both memmove() and bcopy() - that is, hardly ever -
1216        was missing a "static" storage class specifier.
1217    
1218     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
1219        containing an extended class (one that cannot be represented by a bitmap
1220        because it contains high-valued characters or Unicode property items, e.g.
1221        [\pZ]). Almost always one would set UTF-8 mode when processing such a
1222        pattern, but PCRE should not loop if you do not (it no longer does).
1223        [Detail: two cases were found: (a) a repeated subpattern containing an
1224        extended class; (b) a recursive reference to a subpattern that followed a
1225        previous extended class. It wasn't skipping over the extended class
1226        correctly when UTF-8 mode was not set.]
1227    
1228     5. A negated single-character class was not being recognized as fixed-length
1229        in lookbehind assertions such as (?<=[^f]), leading to an incorrect
1230        compile error "lookbehind assertion is not fixed length".
1231    
1232     6. The RunPerlTest auxiliary script was showing an unexpected difference
1233        between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
1234        write a Perl script that can interpret lines of an input file either as
1235        byte characters or as UTF-8, which is what "perltest" was being required to
1236        do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
1237        can't do is switch easily at run time between having the "use utf8;" pragma
1238        or not. In the end, I fudged it by using the RunPerlTest script to insert
1239        "use utf8;" explicitly for the UTF-8 tests.
1240    
1241     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
1242        the end of the subject string, contrary to the documentation and to what
1243        Perl does. This was true of both matching functions. Now it matches only at
1244        the start of the subject and immediately after *internal* newlines.
1245    
1246     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
1247        a pointer to an int instead of a pointer to an unsigned long int. This
1248        caused problems on 64-bit systems.
1249    
1250     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
1251        instance of the 'standard' template library not being so standard".
1252    
1253    10. There was no check on the number of named subpatterns nor the maximum
1254        length of a subpattern name. The product of these values is used to compute
1255        the size of the memory block for a compiled pattern. By supplying a very
1256        long subpattern name and a large number of named subpatterns, the size
1257        computation could be caused to overflow. This is now prevented by limiting
1258        the length of names to 32 characters, and the number of named subpatterns
1259        to 10,000.
1260    
1261    11. Subpatterns that are repeated with specific counts have to be replicated in
1262        the compiled pattern. The size of memory for this was computed from the
1263        length of the subpattern and the repeat count. The latter is limited to
1264        65535, but there was no limit on the former, meaning that integer overflow
1265        could in principle occur. The compiled length of a repeated subpattern is
1266        now limited to 30,000 bytes in order to prevent this.
1267    
1268    12. Added the optional facility to have named substrings with the same name.
1269    
1270    13. Added the ability to use a named substring as a condition, using the
1271        Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
1272        are numbers (not recommended). Forward references are permitted.
1273    
1274    14. Added forward references in named backreferences (if you see what I mean).
1275    
1276    15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
1277        pattern could run off the end of the subject. For example, the pattern
1278        "(?s)(.{1,5})"8 did this with the subject "ab".
1279    
1280    16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
1281        PCRE_CASELESS was set when matching characters that were quantified with ?
1282        or *.
1283    
1284    17. A character class other than a single negated character that had a minimum
1285        but no maximum quantifier - for example [ab]{6,} - was not handled
1286        correctly by pce_dfa_exec(). It would match only one character.
1287    
1288    18. A valid (though odd) pattern that looked like a POSIX character
1289        class but used an invalid character after [ (for example [[,abc,]]) caused
1290        pcre_compile() to give the error "Failed: internal error: code overflow" or
1291        in some cases to crash with a glibc free() error. This could even happen if
1292        the pattern terminated after [[ but there just happened to be a sequence of
1293        letters, a binary zero, and a closing ] in the memory that followed.
1294    
1295    19. Perl's treatment of octal escapes in the range \400 to \777 has changed
1296        over the years. Originally (before any Unicode support), just the bottom 8
1297        bits were taken. Thus, for example, \500 really meant \100. Nowadays the
1298        output from "man perlunicode" includes this:
1299    
1300          The regular expression compiler produces polymorphic opcodes.  That
1301          is, the pattern adapts to the data and automatically switches to
1302          the Unicode character scheme when presented with Unicode data--or
1303          instead uses a traditional byte scheme when presented with byte
1304          data.
1305    
1306        Sadly, a wide octal escape does not cause a switch, and in a string with
1307        no other multibyte characters, these octal escapes are treated as before.
1308        Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
1309        /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
1310        Unicode string.
1311    
1312        I have not perpetrated such confusion in PCRE. Up till now, it took just
1313        the bottom 8 bits, as in old Perl. I have now made octal escapes with
1314        values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
1315        translate to the appropriate multibyte character.
1316    
1317    29. Applied some refactoring to reduce the number of warnings from Microsoft
1318        and Borland compilers. This has included removing the fudge introduced
1319        seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
1320        a warning about an unused variable.
1321    
1322    21. PCRE has not included VT (character 0x0b) in the set of whitespace
1323        characters since release 4.0, because Perl (from release 5.004) does not.
1324        [Or at least, is documented not to: some releases seem to be in conflict
1325        with the documentation.] However, when a pattern was studied with
1326        pcre_study() and all its branches started with \s, PCRE still included VT
1327        as a possible starting character. Of course, this did no harm; it just
1328        caused an unnecessary match attempt.
1329    
1330    22. Removed a now-redundant internal flag bit that recorded the fact that case
1331        dependency changed within the pattern. This was once needed for "required
1332        byte" processing, but is no longer used. This recovers a now-scarce options
1333        bit. Also moved the least significant internal flag bit to the most-
1334        significant bit of the word, which was not previously used (hangover from
1335        the days when it was an int rather than a uint) to free up another bit for
1336        the future.
1337    
1338    23. Added support for CRLF line endings as well as CR and LF. As well as the
1339        default being selectable at build time, it can now be changed at runtime
1340        via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
1341        specify that it is scanning data with non-default line endings.
1342    
1343    24. Changed the definition of CXXLINK to make it agree with the definition of
1344        LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
1345    
1346    25. Applied Ian Taylor's patches to avoid using another stack frame for tail
1347        recursions. This makes a big different to stack usage for some patterns.
1348    
1349    26. If a subpattern containing a named recursion or subroutine reference such
1350        as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
1351        the space required for the compiled pattern went wrong and gave too small a
1352        value. Depending on the environment, this could lead to "Failed: internal
1353        error: code overflow at offset 49" or "glibc detected double free or
1354        corruption" errors.
1355    
1356    27. Applied patches from Google (a) to support the new newline modes and (b) to
1357        advance over multibyte UTF-8 characters in GlobalReplace.
1358    
1359    28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
1360        difference for some implementation of PCRE in some Windows version.
1361    
1362    29. Added some extra testing facilities to pcretest:
1363    
1364        \q<number>   in a data line sets the "match limit" value
1365        \Q<number>   in a data line sets the "match recursion limt" value
1366        -S <number>  sets the stack size, where <number> is in megabytes
1367    
1368        The -S option isn't available for Windows.
1369    
1370    
1371    Version 6.6 06-Feb-06
1372    ---------------------
1373    
1374     1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
1375        in pcreposix.h. I have copied the definition from pcre.h.
1376    
1377     2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
1378        because pcre.h is no longer a built file.
1379    
1380     3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
1381        not normally included in the compiled code.
1382    
1383    
1384    Version 6.5 01-Feb-06
1385    ---------------------
1386    
1387     1. When using the partial match feature with pcre_dfa_exec(), it was not
1388        anchoring the second and subsequent partial matches at the new starting
1389        point. This could lead to incorrect results. For example, with the pattern
1390        /1234/, partially matching against "123" and then "a4" gave a match.
1391    
1392     2. Changes to pcregrep:
1393    
1394        (a) All non-match returns from pcre_exec() were being treated as failures
1395            to match the line. Now, unless the error is PCRE_ERROR_NOMATCH, an
1396            error message is output. Some extra information is given for the
1397            PCRE_ERROR_MATCHLIMIT and PCRE_ERROR_RECURSIONLIMIT errors, which are
1398            probably the only errors that are likely to be caused by users (by
1399            specifying a regex that has nested indefinite repeats, for instance).
1400            If there are more than 20 of these errors, pcregrep is abandoned.
1401    
1402        (b) A binary zero was treated as data while matching, but terminated the
1403            output line if it was written out. This has been fixed: binary zeroes
1404            are now no different to any other data bytes.
1405    
1406        (c) Whichever of the LC_ALL or LC_CTYPE environment variables is set is
1407            used to set a locale for matching. The --locale=xxxx long option has
1408            been added (no short equivalent) to specify a locale explicitly on the
1409            pcregrep command, overriding the environment variables.
1410    
1411        (d) When -B was used with -n, some line numbers in the output were one less
1412            than they should have been.
1413    
1414        (e) Added the -o (--only-matching) option.
1415    
1416        (f) If -A or -C was used with -c (count only), some lines of context were
1417            accidentally printed for the final match.
1418    
1419        (g) Added the -H (--with-filename) option.
1420    
1421        (h) The combination of options -rh failed to suppress file names for files
1422            that were found from directory arguments.
1423    
1424        (i) Added the -D (--devices) and -d (--directories) options.
1425    
1426        (j) Added the -F (--fixed-strings) option.
1427    
1428        (k) Allow "-" to be used as a file name for -f as well as for a data file.
1429    
1430        (l) Added the --colo(u)r option.
1431    
1432        (m) Added Jeffrey Friedl's -S testing option, but within #ifdefs so that it
1433            is not present by default.
1434    
1435     3. A nasty bug was discovered in the handling of recursive patterns, that is,
1436        items such as (?R) or (?1), when the recursion could match a number of
1437        alternatives. If it matched one of the alternatives, but subsequently,
1438        outside the recursion, there was a failure, the code tried to back up into
1439        the recursion. However, because of the way PCRE is implemented, this is not
1440        possible, and the result was an incorrect result from the match.
1441    
1442        In order to prevent this happening, the specification of recursion has
1443        been changed so that all such subpatterns are automatically treated as
1444        atomic groups. Thus, for example, (?R) is treated as if it were (?>(?R)).
1445    
1446     4. I had overlooked the fact that, in some locales, there are characters for
1447        which isalpha() is true but neither isupper() nor islower() are true. In
1448        the fr_FR locale, for instance, the \xAA and \xBA characters (ordmasculine
1449        and ordfeminine) are like this. This affected the treatment of \w and \W
1450        when they appeared in character classes, but not when they appeared outside
1451        a character class. The bit map for "word" characters is now created
1452        separately from the results of isalnum() instead of just taking it from the
1453        upper, lower, and digit maps. (Plus the underscore character, of course.)
1454    
1455     5. The above bug also affected the handling of POSIX character classes such as
1456        [[:alpha:]] and [[:alnum:]]. These do not have their own bit maps in PCRE's
1457        permanent tables. Instead, the bit maps for such a class were previously
1458        created as the appropriate unions of the upper, lower, and digit bitmaps.
1459        Now they are created by subtraction from the [[:word:]] class, which has
1460        its own bitmap.
1461    
1462     6. The [[:blank:]] character class matches horizontal, but not vertical space.
1463        It is created by subtracting the vertical space characters (\x09, \x0a,
1464        \x0b, \x0c) from the [[:space:]] bitmap. Previously, however, the
1465        subtraction was done in the overall bitmap for a character class, meaning
1466        that a class such as [\x0c[:blank:]] was incorrect because \x0c would not
1467        be recognized. This bug has been fixed.
1468    
1469     7. Patches from the folks at Google:
1470    
1471          (a) pcrecpp.cc: "to handle a corner case that may or may not happen in
1472          real life, but is still worth protecting against".
1473    
1474          (b) pcrecpp.cc: "corrects a bug when negative radixes are used with
1475          regular expressions".
1476    
1477          (c) pcre_scanner.cc: avoid use of std::count() because not all systems
1478          have it.
1479    
1480          (d) Split off pcrecpparg.h from pcrecpp.h and had the former built by
1481          "configure" and the latter not, in order to fix a problem somebody had
1482          with compiling the Arg class on HP-UX.
1483    
1484          (e) Improve the error-handling of the C++ wrapper a little bit.
1485    
1486          (f) New tests for checking recursion limiting.
1487    
1488     8. The pcre_memmove() function, which is used only if the environment does not
1489        have a standard memmove() function (and is therefore rarely compiled),
1490        contained two bugs: (a) use of int instead of size_t, and (b) it was not
1491        returning a result (though PCRE never actually uses the result).
1492    
1493     9. In the POSIX regexec() interface, if nmatch is specified as a ridiculously
1494        large number - greater than INT_MAX/(3*sizeof(int)) - REG_ESPACE is
1495        returned instead of calling malloc() with an overflowing number that would
1496        most likely cause subsequent chaos.
1497    
1498    10. The debugging option of pcretest was not showing the NO_AUTO_CAPTURE flag.
1499    
1500    11. The POSIX flag REG_NOSUB is now supported. When a pattern that was compiled
1501        with this option is matched, the nmatch and pmatch options of regexec() are
1502        ignored.
1503    
1504    12. Added REG_UTF8 to the POSIX interface. This is not defined by POSIX, but is
1505        provided in case anyone wants to the the POSIX interface with UTF-8
1506        strings.
1507    
1508    13. Added CXXLDFLAGS to the Makefile parameters to provide settings only on the
1509        C++ linking (needed for some HP-UX environments).
1510    
1511    14. Avoid compiler warnings in get_ucpname() when compiled without UCP support
1512        (unused parameter) and in the pcre_printint() function (omitted "default"
1513        switch label when the default is to do nothing).
1514    
1515    15. Added some code to make it possible, when PCRE is compiled as a C++
1516        library, to replace subject pointers for pcre_exec() with a smart pointer
1517        class, thus making it possible to process discontinuous strings.
1518    
1519    16. The two macros PCRE_EXPORT and PCRE_DATA_SCOPE are confusing, and perform
1520        much the same function. They were added by different people who were trying
1521        to make PCRE easy to compile on non-Unix systems. It has been suggested
1522        that PCRE_EXPORT be abolished now that there is more automatic apparatus
1523        for compiling on Windows systems. I have therefore replaced it with
1524        PCRE_DATA_SCOPE. This is set automatically for Windows; if not set it
1525        defaults to "extern" for C or "extern C" for C++, which works fine on
1526        Unix-like systems. It is now possible to override the value of PCRE_DATA_
1527        SCOPE with something explicit in config.h. In addition:
1528    
1529        (a) pcreposix.h still had just "extern" instead of either of these macros;
1530            I have replaced it with PCRE_DATA_SCOPE.
1531    
1532        (b) Functions such as _pcre_xclass(), which are internal to the library,
1533            but external in the C sense, all had PCRE_EXPORT in their definitions.
1534            This is apparently wrong for the Windows case, so I have removed it.
1535            (It makes no difference on Unix-like systems.)
1536    
1537    17. Added a new limit, MATCH_LIMIT_RECURSION, which limits the depth of nesting
1538        of recursive calls to match(). This is different to MATCH_LIMIT because
1539        that limits the total number of calls to match(), not all of which increase
1540        the depth of recursion. Limiting the recursion depth limits the amount of
1541        stack (or heap if NO_RECURSE is set) that is used. The default can be set
1542        when PCRE is compiled, and changed at run time. A patch from Google adds
1543        this functionality to the C++ interface.
1544    
1545    18. Changes to the handling of Unicode character properties:
1546    
1547        (a) Updated the table to Unicode 4.1.0.
1548    
1549        (b) Recognize characters that are not in the table as "Cn" (undefined).
1550    
1551        (c) I revised the way the table is implemented to a much improved format
1552            which includes recognition of ranges. It now supports the ranges that
1553            are defined in UnicodeData.txt, and it also amalgamates other
1554            characters into ranges. This has reduced the number of entries in the
1555            table from around 16,000 to around 3,000, thus reducing its size
1556            considerably. I realized I did not need to use a tree structure after
1557            all - a binary chop search is just as efficient. Having reduced the
1558            number of entries, I extended their size from 6 bytes to 8 bytes to
1559            allow for more data.
1560    
1561        (d) Added support for Unicode script names via properties such as \p{Han}.
1562    
1563    19. In UTF-8 mode, a backslash followed by a non-Ascii character was not
1564        matching that character.
1565    
1566    20. When matching a repeated Unicode property with a minimum greater than zero,
1567        (for example \pL{2,}), PCRE could look past the end of the subject if it
1568        reached it while seeking the minimum number of characters. This could
1569        happen only if some of the characters were more than one byte long, because
1570        there is a check for at least the minimum number of bytes.
1571    
1572    21. Refactored the implementation of \p and \P so as to be more general, to
1573        allow for more different types of property in future. This has changed the
1574        compiled form incompatibly. Anybody with saved compiled patterns that use
1575        \p or \P will have to recompile them.
1576    
1577    22. Added "Any" and "L&" to the supported property types.
1578    
1579    23. Recognize \x{...} as a code point specifier, even when not in UTF-8 mode,
1580        but give a compile time error if the value is greater than 0xff.
1581    
1582    24. The man pages for pcrepartial, pcreprecompile, and pcre_compile2 were
1583        accidentally not being installed or uninstalled.
1584    
1585    25. The pcre.h file was built from pcre.h.in, but the only changes that were
1586        made were to insert the current release number. This seemed silly, because
1587        it made things harder for people building PCRE on systems that don't run
1588        "configure". I have turned pcre.h into a distributed file, no longer built
1589        by "configure", with the version identification directly included. There is
1590        no longer a pcre.h.in file.
1591    
1592        However, this change necessitated a change to the pcre-config script as
1593        well. It is built from pcre-config.in, and one of the substitutions was the
1594        release number. I have updated configure.ac so that ./configure now finds
1595        the release number by grepping pcre.h.
1596    
1597    26. Added the ability to run the tests under valgrind.
1598    
1599    
1600    Version 6.4 05-Sep-05
1601    ---------------------
1602    
1603     1. Change 6.0/10/(l) to pcregrep introduced a bug that caused separator lines
1604        "--" to be printed when multiple files were scanned, even when none of the
1605        -A, -B, or -C options were used. This is not compatible with Gnu grep, so I
1606        consider it to be a bug, and have restored the previous behaviour.
1607    
1608     2. A couple of code tidies to get rid of compiler warnings.
1609    
1610     3. The pcretest program used to cheat by referring to symbols in the library
1611        whose names begin with _pcre_. These are internal symbols that are not
1612        really supposed to be visible externally, and in some environments it is
1613        possible to suppress them. The cheating is now confined to including
1614        certain files from the library's source, which is a bit cleaner.
1615    
1616     4. Renamed pcre.in as pcre.h.in to go with pcrecpp.h.in; it also makes the
1617        file's purpose clearer.
1618    
1619     5. Reorganized pcre_ucp_findchar().
1620    
1621    
1622    Version 6.3 15-Aug-05
1623    ---------------------
1624    
1625     1. The file libpcre.pc.in did not have general read permission in the tarball.
1626    
1627     2. There were some problems when building without C++ support:
1628    
1629        (a) If C++ support was not built, "make install" and "make test" still
1630            tried to test it.
1631    
1632        (b) There were problems when the value of CXX was explicitly set. Some
1633            changes have been made to try to fix these, and ...
1634    
1635        (c) --disable-cpp can now be used to explicitly disable C++ support.
1636    
1637        (d) The use of @CPP_OBJ@ directly caused a blank line preceded by a
1638            backslash in a target when C++ was disabled. This confuses some
1639            versions of "make", apparently. Using an intermediate variable solves
1640            this. (Same for CPP_LOBJ.)
1641    
1642     3. $(LINK_FOR_BUILD) now includes $(CFLAGS_FOR_BUILD) and $(LINK)
1643        (non-Windows) now includes $(CFLAGS) because these flags are sometimes
1644        necessary on certain architectures.
1645    
1646     4. Added a setting of -export-symbols-regex to the link command to remove
1647        those symbols that are exported in the C sense, but actually are local
1648        within the library, and not documented. Their names all begin with
1649        "_pcre_". This is not a perfect job, because (a) we have to except some
1650        symbols that pcretest ("illegally") uses, and (b) the facility isn't always
1651        available (and never for static libraries). I have made a note to try to
1652        find a way round (a) in the future.
1653    
1654    
1655    Version 6.2 01-Aug-05
1656    ---------------------
1657    
1658     1. There was no test for integer overflow of quantifier values. A construction
1659        such as {1111111111111111} would give undefined results. What is worse, if
1660        a minimum quantifier for a parenthesized subpattern overflowed and became
1661        negative, the calculation of the memory size went wrong. This could have
1662        led to memory overwriting.
1663    
1664     2. Building PCRE using VPATH was broken. Hopefully it is now fixed.
1665    
1666     3. Added "b" to the 2nd argument of fopen() in dftables.c, for non-Unix-like
1667        operating environments where this matters.
1668    
1669     4. Applied Giuseppe Maxia's patch to add additional features for controlling
1670        PCRE options from within the C++ wrapper.
1671    
1672     5. Named capturing subpatterns were not being correctly counted when a pattern
1673        was compiled. This caused two problems: (a) If there were more than 100
1674        such subpatterns, the calculation of the memory needed for the whole
1675        compiled pattern went wrong, leading to an overflow error. (b) Numerical
1676        back references of the form \12, where the number was greater than 9, were
1677        not recognized as back references, even though there were sufficient
1678        previous subpatterns.
1679    
1680     6. Two minor patches to pcrecpp.cc in order to allow it to compile on older
1681        versions of gcc, e.g. 2.95.4.
1682    
1683    
1684    Version 6.1 21-Jun-05
1685    ---------------------
1686    
1687     1. There was one reference to the variable "posix" in pcretest.c that was not
1688        surrounded by "#if !defined NOPOSIX".
1689    
1690     2. Make it possible to compile pcretest without DFA support, UTF8 support, or
1691        the cross-check on the old pcre_info() function, for the benefit of the
1692        cut-down version of PCRE that is currently imported into Exim.
1693    
1694     3. A (silly) pattern starting with (?i)(?-i) caused an internal space
1695        allocation error. I've done the easy fix, which wastes 2 bytes for sensible
1696        patterns that start (?i) but I don't think that matters. The use of (?i) is
1697        just an example; this all applies to the other options as well.
1698    
1699     4. Since libtool seems to echo the compile commands it is issuing, the output
1700        from "make" can be reduced a bit by putting "@" in front of each libtool
1701        compile command.
1702    
1703     5. Patch from the folks at Google for configure.in to be a bit more thorough
1704        in checking for a suitable C++ installation before trying to compile the
1705        C++ stuff. This should fix a reported problem when a compiler was present,
1706        but no suitable headers.
1707    
1708     6. The man pages all had just "PCRE" as their title. I have changed them to
1709        be the relevant file name. I have also arranged that these names are
1710        retained in the file doc/pcre.txt, which is a concatenation in text format
1711        of all the man pages except the little individual ones for each function.
1712    
1713     7. The NON-UNIX-USE file had not been updated for the different set of source
1714        files that come with release 6. I also added a few comments about the C++
1715        wrapper.
1716    
1717    
1718    Version 6.0 07-Jun-05
1719    ---------------------
1720    
1721     1. Some minor internal re-organization to help with my DFA experiments.
1722    
1723     2. Some missing #ifdef SUPPORT_UCP conditionals in pcretest and printint that
1724        didn't matter for the library itself when fully configured, but did matter
1725        when compiling without UCP support, or within Exim, where the ucp files are
1726        not imported.
1727    
1728     3. Refactoring of the library code to split up the various functions into
1729        different source modules. The addition of the new DFA matching code (see
1730        below) to a single monolithic source would have made it really too
1731        unwieldy, quite apart from causing all the code to be include in a
1732        statically linked application, when only some functions are used. This is
1733        relevant even without the DFA addition now that patterns can be compiled in
1734        one application and matched in another.
1735    
1736        The downside of splitting up is that there have to be some external
1737        functions and data tables that are used internally in different modules of
1738        the library but which are not part of the API. These have all had their
1739        names changed to start with "_pcre_" so that they are unlikely to clash
1740        with other external names.
1741    
1742     4. Added an alternate matching function, pcre_dfa_exec(), which matches using
1743        a different (DFA) algorithm. Although it is slower than the original
1744        function, it does have some advantages for certain types of matching
1745        problem.
1746    
1747     5. Upgrades to pcretest in order to test the features of pcre_dfa_exec(),
1748        including restarting after a partial match.
1749    
1750     6. A patch for pcregrep that defines INVALID_FILE_ATTRIBUTES if it is not
1751        defined when compiling for Windows was sent to me. I have put it into the
1752        code, though I have no means of testing or verifying it.
1753    
1754     7. Added the pcre_refcount() auxiliary function.
1755    
1756     8. Added the PCRE_FIRSTLINE option. This constrains an unanchored pattern to
1757        match before or at the first newline in the subject string. In pcretest,
1758        the /f option on a pattern can be used to set this.
1759    
1760     9. A repeated \w when used in UTF-8 mode with characters greater than 256
1761        would behave wrongly. This has been present in PCRE since release 4.0.
1762    
1763    10. A number of changes to the pcregrep command:
1764    
1765        (a) Refactored how -x works; insert ^(...)$ instead of setting
1766            PCRE_ANCHORED and checking the length, in preparation for adding
1767            something similar for -w.
1768    
1769        (b) Added the -w (match as a word) option.
1770    
1771        (c) Refactored the way lines are read and buffered so as to have more
1772            than one at a time available.
1773    
1774        (d) Implemented a pcregrep test script.
1775    
1776        (e) Added the -M (multiline match) option. This allows patterns to match
1777            over several lines of the subject. The buffering ensures that at least
1778            8K, or the rest of the document (whichever is the shorter) is available
1779            for matching (and similarly the previous 8K for lookbehind assertions).
1780    
1781        (f) Changed the --help output so that it now says
1782    
1783              -w, --word-regex(p)
1784    
1785            instead of two lines, one with "regex" and the other with "regexp"
1786            because that confused at least one person since the short forms are the
1787            same. (This required a bit of code, as the output is generated
1788            automatically from a table. It wasn't just a text change.)
1789    
1790        (g) -- can be used to terminate pcregrep options if the next thing isn't an
1791            option but starts with a hyphen. Could be a pattern or a path name
1792            starting with a hyphen, for instance.
1793    
1794        (h) "-" can be given as a file name to represent stdin.
1795    
1796        (i) When file names are being printed, "(standard input)" is used for
1797            the standard input, for compatibility with GNU grep. Previously
1798            "<stdin>" was used.
1799    
1800        (j) The option --label=xxx can be used to supply a name to be used for
1801            stdin when file names are being printed. There is no short form.
1802    
1803        (k) Re-factored the options decoding logic because we are going to add
1804            two more options that take data. Such options can now be given in four
1805            different ways, e.g. "-fname", "-f name", "--file=name", "--file name".
1806    
1807        (l) Added the -A, -B, and -C options for requesting that lines of context
1808            around matches be printed.
1809    
1810        (m) Added the -L option to print the names of files that do not contain
1811            any matching lines, that is, the complement of -l.
1812    
1813        (n) The return code is 2 if any file cannot be opened, but pcregrep does
1814            continue to scan other files.
1815    
1816        (o) The -s option was incorrectly implemented. For compatibility with other
1817            greps, it now suppresses the error message for a non-existent or non-
1818            accessible file (but not the return code). There is a new option called
1819            -q that suppresses the output of matching lines, which was what -s was
1820            previously doing.
1821    
1822        (p) Added --include and --exclude options to specify files for inclusion
1823            and exclusion when recursing.
1824    
1825    11. The Makefile was not using the Autoconf-supported LDFLAGS macro properly.
1826        Hopefully, it now does.
1827    
1828    12. Missing cast in pcre_study().
1829    
1830    13. Added an "uninstall" target to the makefile.
1831    
1832    14. Replaced "extern" in the function prototypes in Makefile.in with
1833        "PCRE_DATA_SCOPE", which defaults to 'extern' or 'extern "C"' in the Unix
1834        world, but is set differently for Windows.
1835    
1836    15. Added a second compiling function called pcre_compile2(). The only
1837        difference is that it has an extra argument, which is a pointer to an
1838        integer error code. When there is a compile-time failure, this is set
1839        non-zero, in addition to the error test pointer being set to point to an
1840        error message. The new argument may be NULL if no error number is required
1841        (but then you may as well call pcre_compile(), which is now just a
1842        wrapper). This facility is provided because some applications need a
1843        numeric error indication, but it has also enabled me to tidy up the way
1844        compile-time errors are handled in the POSIX wrapper.
1845    
1846    16. Added VPATH=.libs to the makefile; this should help when building with one
1847        prefix path and installing with another. (Or so I'm told by someone who
1848        knows more about this stuff than I do.)
1849    
1850    17. Added a new option, REG_DOTALL, to the POSIX function regcomp(). This
1851        passes PCRE_DOTALL to the pcre_compile() function, making the "." character
1852        match everything, including newlines. This is not POSIX-compatible, but
1853        somebody wanted the feature. From pcretest it can be activated by using
1854        both the P and the s flags.
1855    
1856    18. AC_PROG_LIBTOOL appeared twice in Makefile.in. Removed one.
1857    
1858    19. libpcre.pc was being incorrectly installed as executable.
1859    
1860    20. A couple of places in pcretest check for end-of-line by looking for '\n';
1861        it now also looks for '\r' so that it will work unmodified on Windows.
1862    
1863    21. Added Google's contributed C++ wrapper to the distribution.
1864    
1865    22. Added some untidy missing memory free() calls in pcretest, to keep
1866        Electric Fence happy when testing.
1867    
1868    
1869    
1870    Version 5.0 13-Sep-04
1871    ---------------------
1872    
1873     1. Internal change: literal characters are no longer packed up into items
1874        containing multiple characters in a single byte-string. Each character
1875        is now matched using a separate opcode. However, there may be more than one
1876        byte in the character in UTF-8 mode.
1877    
1878     2. The pcre_callout_block structure has two new fields: pattern_position and
1879        next_item_length. These contain the offset in the pattern to the next match
1880        item, and its length, respectively.
1881    
1882     3. The PCRE_AUTO_CALLOUT option for pcre_compile() requests the automatic
1883        insertion of callouts before each pattern item. Added the /C option to
1884        pcretest to make use of this.
1885    
1886     4. On the advice of a Windows user, the lines
1887    
1888          #if defined(_WIN32) || defined(WIN32)
1889          _setmode( _fileno( stdout ), 0x8000 );
1890          #endif  /* defined(_WIN32) || defined(WIN32) */
1891    
1892        have been added to the source of pcretest. This apparently does useful
1893        magic in relation to line terminators.
1894    
1895     5. Changed "r" and "w" in the calls to fopen() in pcretest to "rb" and "wb"
1896        for the benefit of those environments where the "b" makes a difference.
1897    
1898     6. The icc compiler has the same options as gcc, but "configure" doesn't seem
1899        to know about it. I have put a hack into configure.in that adds in code
1900        to set GCC=yes if CC=icc. This seems to end up at a point in the
1901        generated configure script that is early enough to affect the setting of
1902        compiler options, which is what is needed, but I have no means of testing
1903        whether it really works. (The user who reported this had patched the
1904        generated configure script, which of course I cannot do.)
1905    
1906        LATER: After change 22 below (new libtool files), the configure script
1907        seems to know about icc (and also ecc). Therefore, I have commented out
1908        this hack in configure.in.
1909    
1910     7. Added support for pkg-config (2 patches were sent in).
1911    
1912     8. Negated POSIX character classes that used a combination of internal tables
1913        were completely broken. These were [[:^alpha:]], [[:^alnum:]], and
1914        [[:^ascii]]. Typically, they would match almost any characters. The other
1915        POSIX classes were not broken in this way.
1916    
1917     9. Matching the pattern "\b.*?" against "ab cd", starting at offset 1, failed
1918        to find the match, as PCRE was deluded into thinking that the match had to
1919        start at the start point or following a newline. The same bug applied to
1920        patterns with negative forward assertions or any backward assertions
1921        preceding ".*" at the start, unless the pattern required a fixed first
1922        character. This was a failing pattern: "(?!.bcd).*". The bug is now fixed.
1923    
1924    10. In UTF-8 mode, when moving forwards in the subject after a failed match
1925        starting at the last subject character, bytes beyond the end of the subject
1926        string were read.
1927    
1928    11. Renamed the variable "class" as "classbits" to make life easier for C++
1929        users. (Previously there was a macro definition, but it apparently wasn't
1930        enough.)
1931    
1932    12. Added the new field "tables" to the extra data so that tables can be passed
1933        in at exec time, or the internal tables can be re-selected. This allows
1934        a compiled regex to be saved and re-used at a later time by a different
1935        program that might have everything at different addresses.
1936    
1937    13. Modified the pcre-config script so that, when run on Solaris, it shows a
1938        -R library as well as a -L library.
1939    
1940    14. The debugging options of pcretest (-d on the command line or D on a
1941        pattern) showed incorrect output for anything following an extended class
1942        that contained multibyte characters and which was followed by a quantifier.
1943    
1944    15. Added optional support for general category Unicode character properties
1945        via the \p, \P, and \X escapes. Unicode property support implies UTF-8
1946        support. It adds about 90K to the size of the library. The meanings of the
1947        inbuilt class escapes such as \d and \s have NOT been changed.
1948    
1949    16. Updated pcredemo.c to include calls to free() to release the memory for the
1950        compiled pattern.
1951    
1952    17. The generated file chartables.c was being created in the source directory
1953        instead of in the building directory. This caused the build to fail if the
1954        source directory was different from the building directory, and was
1955        read-only.
1956    
1957    18. Added some sample Win commands from Mark Tetrode into the NON-UNIX-USE
1958        file. No doubt somebody will tell me if they don't make sense... Also added
1959        Dan Mooney's comments about building on OpenVMS.
1960    
1961    19. Added support for partial matching via the PCRE_PARTIAL option for
1962        pcre_exec() and the \P data escape in pcretest.
1963    
1964    20. Extended pcretest with 3 new pattern features:
1965    
1966        (i)   A pattern option of the form ">rest-of-line" causes pcretest to
1967              write the compiled pattern to the file whose name is "rest-of-line".
1968              This is a straight binary dump of the data, with the saved pointer to
1969              the character tables forced to be NULL. The study data, if any, is
1970              written too. After writing, pcretest reads a new pattern.
1971    
1972        (ii)  If, instead of a pattern, "<rest-of-line" is given, pcretest reads a
1973              compiled pattern from the given file. There must not be any
1974              occurrences of "<" in the file name (pretty unlikely); if there are,
1975              pcretest will instead treat the initial "<" as a pattern delimiter.
1976              After reading in the pattern, pcretest goes on to read data lines as
1977              usual.
1978    
1979        (iii) The F pattern option causes pcretest to flip the bytes in the 32-bit
1980              and 16-bit fields in a compiled pattern, to simulate a pattern that
1981              was compiled on a host of opposite endianness.
1982    
1983    21. The pcre-exec() function can now cope with patterns that were compiled on
1984        hosts of opposite endianness, with this restriction:
1985    
1986          As for any compiled expression that is saved and used later, the tables
1987          pointer field cannot be preserved; the extra_data field in the arguments
1988          to pcre_exec() should be used to pass in a tables address if a value
1989          other than the default internal tables were used at compile time.
1990    
1991    22. Calling pcre_exec() with a negative value of the "ovecsize" parameter is
1992        now diagnosed as an error. Previously, most of the time, a negative number
1993        would have been treated as zero, but if in addition "ovector" was passed as
1994        NULL, a crash could occur.
1995    
1996    23. Updated the files ltmain.sh, config.sub, config.guess, and aclocal.m4 with
1997        new versions from the libtool 1.5 distribution (the last one is a copy of
1998        a file called libtool.m4). This seems to have fixed the need to patch
1999        "configure" to support Darwin 1.3 (which I used to do). However, I still
2000        had to patch ltmain.sh to ensure that ${SED} is set (it isn't on my
2001        workstation).
2002    
2003    24. Changed the PCRE licence to be the more standard "BSD" licence.
2004    
2005    
2006    Version 4.5 01-Dec-03
2007    ---------------------
2008    
2009     1. There has been some re-arrangement of the code for the match() function so
2010        that it can be compiled in a version that does not call itself recursively.
2011        Instead, it keeps those local variables that need separate instances for
2012        each "recursion" in a frame on the heap, and gets/frees frames whenever it
2013        needs to "recurse". Keeping track of where control must go is done by means
2014        of setjmp/longjmp. The whole thing is implemented by a set of macros that
2015        hide most of the details from the main code, and operates only if
2016        NO_RECURSE is defined while compiling pcre.c. If PCRE is built using the
2017        "configure" mechanism, "--disable-stack-for-recursion" turns on this way of
2018        operating.
2019    
2020        To make it easier for callers to provide specially tailored get/free
2021        functions for this usage, two new functions, pcre_stack_malloc, and
2022        pcre_stack_free, are used. They are always called in strict stacking order,
2023        and the size of block requested is always the same.
2024    
2025        The PCRE_CONFIG_STACKRECURSE info parameter can be used to find out whether
2026        PCRE has been compiled to use the stack or the heap for recursion. The
2027        -C option of pcretest uses this to show which version is compiled.
2028    
2029        A new data escape \S, is added to pcretest; it causes the amounts of store
2030        obtained and freed by both kinds of malloc/free at match time to be added
2031        to the output.
2032    
2033     2. Changed the locale test to use "fr_FR" instead of "fr" because that's
2034        what's available on my current Linux desktop machine.
2035    
2036     3. When matching a UTF-8 string, the test for a valid string at the start has
2037        been extended. If start_offset is not zero, PCRE now checks that it points
2038        to a byte that is the start of a UTF-8 character. If not, it returns
2039        PCRE_ERROR_BADUTF8_OFFSET (-11). Note: the whole string is still checked;
2040        this is necessary because there may be backward assertions in the pattern.
2041        When matching the same subject several times, it may save resources to use
2042        PCRE_NO_UTF8_CHECK on all but the first call if the string is long.
2043    
2044     4. The code for checking the validity of UTF-8 strings has been tightened so
2045        that it rejects (a) strings containing 0xfe or 0xff bytes and (b) strings
2046        containing "overlong sequences".
2047    
2048     5. Fixed a bug (appearing twice) that I could not find any way of exploiting!
2049        I had written "if ((digitab[*p++] && chtab_digit) == 0)" where the "&&"
2050        should have been "&", but it just so happened that all the cases this let
2051        through by mistake were picked up later in the function.
2052    
2053     6. I had used a variable called "isblank" - this is a C99 function, causing
2054        some compilers to warn. To avoid this, I renamed it (as "blankclass").
2055    
2056     7. Cosmetic: (a) only output another newline at the end of pcretest if it is
2057        prompting; (b) run "./pcretest /dev/null" at the start of the test script
2058        so the version is shown; (c) stop "make test" echoing "./RunTest".
2059    
2060     8. Added patches from David Burgess to enable PCRE to run on EBCDIC systems.
2061    
2062     9. The prototype for memmove() for systems that don't have it was using
2063        size_t, but the inclusion of the header that defines size_t was later. I've
2064        moved the #includes for the C headers earlier to avoid this.
2065    
2066    10. Added some adjustments to the code to make it easier to compiler on certain
2067        special systems:
2068    
2069          (a) Some "const" qualifiers were missing.
2070          (b) Added the macro EXPORT before all exported functions; by default this
2071              is defined to be empty.
2072          (c) Changed the dftables auxiliary program (that builds chartables.c) so
2073              that it reads its output file name as an argument instead of writing
2074              to the standard output and assuming this can be redirected.
2075    
2076    11. In UTF-8 mode, if a recursive reference (e.g. (?1)) followed a character
2077        class containing characters with values greater than 255, PCRE compilation
2078        went into a loop.
2079    
2080    12. A recursive reference to a subpattern that was within another subpattern
2081        that had a minimum quantifier of zero caused PCRE to crash. For example,
2082        (x(y(?2))z)? provoked this bug with a subject that got as far as the
2083        recursion. If the recursively-called subpattern itself had a zero repeat,
2084        that was OK.
2085    
2086    13. In pcretest, the buffer for reading a data line was set at 30K, but the
2087        buffer into which it was copied (for escape processing) was still set at
2088        1024, so long lines caused crashes.
2089    
2090    14. A pattern such as /[ab]{1,3}+/ failed to compile, giving the error
2091        "internal error: code overflow...". This applied to any character class
2092        that was followed by a possessive quantifier.
2093    
2094    15. Modified the Makefile to add libpcre.la as a prerequisite for
2095        libpcreposix.la because I was told this is needed for a parallel build to
2096        work.
2097    
2098    16. If a pattern that contained .* following optional items at the start was
2099        studied, the wrong optimizing data was generated, leading to matching
2100        errors. For example, studying /[ab]*.*c/ concluded, erroneously, that any
2101        matching string must start with a or b or c. The correct conclusion for
2102        this pattern is that a match can start with any character.
2103    
2104    
2105    Version 4.4 13-Aug-03
2106    ---------------------
2107    
2108     1. In UTF-8 mode, a character class containing characters with values between
2109        127 and 255 was not handled correctly if the compiled pattern was studied.
2110        In fixing this, I have also improved the studying algorithm for such
2111        classes (slightly).
2112    
2113     2. Three internal functions had redundant arguments passed to them. Removal
2114        might give a very teeny performance improvement.
2115    
2116     3. Documentation bug: the value of the capture_top field in a callout is *one
2117        more than* the number of the hightest numbered captured substring.
2118    
2119     4. The Makefile linked pcretest and pcregrep with -lpcre, which could result
2120        in incorrectly linking with a previously installed version. They now link
2121        explicitly with libpcre.la.
2122    
2123     5. configure.in no longer needs to recognize Cygwin specially.
2124    
2125     6. A problem in pcre.in for Windows platforms is fixed.
2126    
2127     7. If a pattern was successfully studied, and the -d (or /D) flag was given to
2128        pcretest, it used to include the size of the study block as part of its
2129        output. Unfortunately, the structure contains a field that has a different
2130        size on different hardware architectures. This meant that the tests that
2131        showed this size failed. As the block is currently always of a fixed size,
2132        this information isn't actually particularly useful in pcretest output, so
2133        I have just removed it.
2134    
2135     8. Three pre-processor statements accidentally did not start in column 1.
2136        Sadly, there are *still* compilers around that complain, even though
2137        standard C has not required this for well over a decade. Sigh.
2138    
2139     9. In pcretest, the code for checking callouts passed small integers in the
2140        callout_data field, which is a void * field. However, some picky compilers
2141        complained about the casts involved for this on 64-bit systems. Now
2142        pcretest passes the address of the small integer instead, which should get
2143        rid of the warnings.
2144    
2145    10. By default, when in UTF-8 mode, PCRE now checks for valid UTF-8 strings at
2146        both compile and run time, and gives an error if an invalid UTF-8 sequence
2147        is found. There is a option for disabling this check in cases where the
2148        string is known to be correct and/or the maximum performance is wanted.
2149    
2150    11. In response to a bug report, I changed one line in Makefile.in from
2151    
2152            -Wl,--out-implib,.libs/lib@WIN_PREFIX@pcreposix.dll.a \
2153        to
2154            -Wl,--out-implib,.libs/@WIN_PREFIX@libpcreposix.dll.a \
2155    
2156        to look similar to other lines, but I have no way of telling whether this
2157        is the right thing to do, as I do not use Windows. No doubt I'll get told
2158        if it's wrong...
2159    
2160    
2161    Version 4.3 21-May-03
2162    ---------------------
2163    
2164    1. Two instances of @WIN_PREFIX@ omitted from the Windows targets in the
2165       Makefile.
2166    
2167    2. Some refactoring to improve the quality of the code:
2168    
2169       (i)   The utf8_table... variables are now declared "const".
2170    
2171       (ii)  The code for \cx, which used the "case flipping" table to upper case
2172             lower case letters, now just substracts 32. This is ASCII-specific,
2173             but the whole concept of \cx is ASCII-specific, so it seems
2174             reasonable.
2175    
2176       (iii) PCRE was using its character types table to recognize decimal and
2177             hexadecimal digits in the pattern. This is silly, because it handles
2178             only 0-9, a-f, and A-F, but the character types table is locale-
2179             specific, which means strange things might happen. A private
2180             table is now used for this - though it costs 256 bytes, a table is
2181             much faster than multiple explicit tests. Of course, the standard
2182             character types table is still used for matching digits in subject
2183             strings against \d.
2184    
2185       (iv)  Strictly, the identifier ESC_t is reserved by POSIX (all identifiers
2186             ending in _t are). So I've renamed it as ESC_tee.
2187    
2188    3. The first argument for regexec() in the POSIX wrapper should have been
2189       defined as "const".
2190    
2191    4. Changed pcretest to use malloc() for its buffers so that they can be
2192       Electric Fenced for debugging.
2193    
2194    5. There were several places in the code where, in UTF-8 mode, PCRE would try
2195       to read one or more bytes before the start of the subject string. Often this
2196       had no effect on PCRE's behaviour, but in some circumstances it could
2197       provoke a segmentation fault.
2198    
2199    6. A lookbehind at the start of a pattern in UTF-8 mode could also cause PCRE
2200       to try to read one or more bytes before the start of the subject string.
2201    
2202    7. A lookbehind in a pattern matched in non-UTF-8 mode on a PCRE compiled with
2203       UTF-8 support could misbehave in various ways if the subject string
2204       contained bytes with the 0x80 bit set and the 0x40 bit unset in a lookbehind
2205       area. (PCRE was not checking for the UTF-8 mode flag, and trying to move
2206       back over UTF-8 characters.)
2207    
2208    
2209    Version 4.2 14-Apr-03
2210    ---------------------
2211    
2212    1. Typo "#if SUPPORT_UTF8" instead of "#ifdef SUPPORT_UTF8" fixed.
2213    
2214    2. Changes to the building process, supplied by Ronald Landheer-Cieslak
2215         [ON_WINDOWS]: new variable, "#" on non-Windows platforms
2216         [NOT_ON_WINDOWS]: new variable, "#" on Windows platforms
2217         [WIN_PREFIX]: new variable, "cyg" for Cygwin
2218         * Makefile.in: use autoconf substitution for OBJEXT, EXEEXT, BUILD_OBJEXT
2219           and BUILD_EXEEXT
2220         Note: automatic setting of the BUILD variables is not yet working
2221         set CPPFLAGS and BUILD_CPPFLAGS (but don't use yet) - should be used at
2222           compile-time but not at link-time
2223         [LINK]: use for linking executables only
2224         make different versions for Windows and non-Windows
2225         [LINKLIB]: new variable, copy of UNIX-style LINK, used for linking
2226           libraries
2227         [LINK_FOR_BUILD]: new variable
2228         [OBJEXT]: use throughout
2229         [EXEEXT]: use throughout
2230         <winshared>: new target
2231         <wininstall>: new target
2232         <dftables.o>: use native compiler
2233         <dftables>: use native linker
2234         <install>: handle Windows platform correctly
2235         <clean>: ditto
2236         <check>: ditto
2237         copy DLL to top builddir before testing
2238    
2239       As part of these changes, -no-undefined was removed again. This was reported
2240       to give trouble on HP-UX 11.0, so getting rid of it seems like a good idea
2241       in any case.
2242    
2243    3. Some tidies to get rid of compiler warnings:
2244    
2245       . In the match_data structure, match_limit was an unsigned long int, whereas
2246         match_call_count was an int. I've made them both unsigned long ints.
2247    
2248       . In pcretest the fact that a const uschar * doesn't automatically cast to
2249         a void * provoked a warning.
2250    
2251       . Turning on some more compiler warnings threw up some "shadow" variables
2252         and a few more missing casts.
2253    
2254    4. If PCRE was complied with UTF-8 support, but called without the PCRE_UTF8
2255       option, a class that contained a single character with a value between 128
2256       and 255 (e.g. /[\xFF]/) caused PCRE to crash.
2257    
2258    5. If PCRE was compiled with UTF-8 support, but called without the PCRE_UTF8
2259       option, a class that contained several characters, but with at least one
2260       whose value was between 128 and 255 caused PCRE to crash.
2261    
2262    
2263    Version 4.1 12-Mar-03
2264    ---------------------
2265    
2266    1. Compiling with gcc -pedantic found a couple of places where casts were
2267    needed, and a string in dftables.c that was longer than standard compilers are
2268    required to support.
2269    
2270    2. Compiling with Sun's compiler found a few more places where the code could
2271    be tidied up in order to avoid warnings.
2272    
2273    3. The variables for cross-compiling were called HOST_CC and HOST_CFLAGS; the
2274    first of these names is deprecated in the latest Autoconf in favour of the name
2275    CC_FOR_BUILD, because "host" is typically used to mean the system on which the
2276    compiled code will be run. I can't find a reference for HOST_CFLAGS, but by
2277    analogy I have changed it to CFLAGS_FOR_BUILD.
2278    
2279    4. Added -no-undefined to the linking command in the Makefile, because this is
2280    apparently helpful for Windows. To make it work, also added "-L. -lpcre" to the
2281    linking step for the pcreposix library.
2282    
2283    5. PCRE was failing to diagnose the case of two named groups with the same
2284    name.
2285    
2286    6. A problem with one of PCRE's optimizations was discovered. PCRE remembers a
2287    literal character that is needed in the subject for a match, and scans along to
2288    ensure that it is present before embarking on the full matching process. This
2289    saves time in cases of nested unlimited repeats that are never going to match.
2290    Problem: the scan can take a lot of time if the subject is very long (e.g.
2291    megabytes), thus penalizing straightforward matches. It is now done only if the
2292    amount of subject to be scanned is less than 1000 bytes.
2293    
2294    7. A lesser problem with the same optimization is that it was recording the
2295    first character of an anchored pattern as "needed", thus provoking a search
2296    right along the subject, even when the first match of the pattern was going to
2297    fail. The "needed" character is now not set for anchored patterns, unless it
2298    follows something in the pattern that is of non-fixed length. Thus, it still
2299    fulfils its original purpose of finding quick non-matches in cases of nested
2300    unlimited repeats, but isn't used for simple anchored patterns such as /^abc/.
2301    
2302    
2303    Version 4.0 17-Feb-03
2304    ---------------------
2305    
2306    1. If a comment in an extended regex that started immediately after a meta-item
2307    extended to the end of string, PCRE compiled incorrect data. This could lead to
2308    all kinds of weird effects. Example: /#/ was bad; /()#/ was bad; /a#/ was not.
2309    
2310    2. Moved to autoconf 2.53 and libtool 1.4.2.
2311    
2312    3. Perl 5.8 no longer needs "use utf8" for doing UTF-8 things. Consequently,
2313    the special perltest8 script is no longer needed - all the tests can be run
2314    from a single perltest script.
2315    
2316    4. From 5.004, Perl has not included the VT character (0x0b) in the set defined
2317    by \s. It has now been removed in PCRE. This means it isn't recognized as
2318    whitespace in /x regexes too, which is the same as Perl. Note that the POSIX
2319    class [:space:] *does* include VT, thereby creating a mess.
2320    
2321    5. Added the class [:blank:] (a GNU extension from Perl 5.8) to match only
2322    space and tab.
2323    
2324    6. Perl 5.005 was a long time ago. It's time to amalgamate the tests that use
2325    its new features into the main test script, reducing the number of scripts.
2326    
2327    7. Perl 5.8 has changed the meaning of patterns like /a(?i)b/. Earlier versions
2328    were backward compatible, and made the (?i) apply to the whole pattern, as if
2329    /i were given. Now it behaves more logically, and applies the option setting
2330    only to what follows. PCRE has been changed to follow suit. However, if it
2331    finds options settings right at the start of the pattern, it extracts them into
2332    the global options, as before. Thus, they show up in the info data.
2333    
2334    8. Added support for the \Q...\E escape sequence. Characters in between are
2335    treated as literals. This is slightly different from Perl in that $ and @ are
2336    also handled as literals inside the quotes. In Perl, they will cause variable
2337    interpolation. Note the following examples:
2338    
2339        Pattern            PCRE matches      Perl matches
2340    
2341        \Qabc$xyz\E        abc$xyz           abc followed by the contents of $xyz
2342        \Qabc\$xyz\E       abc\$xyz          abc\$xyz
2343        \Qabc\E\$\Qxyz\E   abc$xyz           abc$xyz
2344    
2345    For compatibility with Perl, \Q...\E sequences are recognized inside character
2346    classes as well as outside them.
2347    
2348    9. Re-organized 3 code statements in pcretest to avoid "overflow in
2349    floating-point constant arithmetic" warnings from a Microsoft compiler. Added a
2350    (size_t) cast to one statement in pcretest and one in pcreposix to avoid
2351    signed/unsigned warnings.
2352    
2353    10. SunOS4 doesn't have strtoul(). This was used only for unpicking the -o
2354    option for pcretest, so I've replaced it by a simple function that does just
2355    that job.
2356    
2357    11. pcregrep was ending with code 0 instead of 2 for the commands "pcregrep" or
2358    "pcregrep -".
2359    
2360    12. Added "possessive quantifiers" ?+, *+, ++, and {,}+ which come from Sun's
2361    Java package. This provides some syntactic sugar for simple cases of what my
2362    documentation calls "once-only subpatterns". A pattern such as x*+ is the same
2363    as (?>x*). In other words, if what is inside (?>...) is just a single repeated
2364    item, you can use this simplified notation. Note that only makes sense with
2365    greedy quantifiers. Consequently, the use of the possessive quantifier forces
2366    greediness, whatever the setting of the PCRE_UNGREEDY option.
2367    
2368    13. A change of greediness default within a pattern was not taking effect at
2369    the current level for patterns like /(b+(?U)a+)/. It did apply to parenthesized
2370    subpatterns that followed. Patterns like /b+(?U)a+/ worked because the option
2371    was abstracted outside.
2372    
2373    14. PCRE now supports the \G assertion. It is true when the current matching
2374    position is at the start point of the match. This differs from \A when the
2375    starting offset is non-zero. Used with the /g option of pcretest (or similar
2376    code), it works in the same way as it does for Perl's /g option. If all
2377    alternatives of a regex begin with \G, the expression is anchored to the start
2378    match position, and the "anchored" flag is set in the compiled expression.
2379    
2380    15. Some bugs concerning the handling of certain option changes within patterns
2381    have been fixed. These applied to options other than (?ims). For example,
2382    "a(?x: b c )d" did not match "XabcdY" but did match "Xa b c dY". It should have
2383    been the other way round. Some of this was related to change 7 above.
2384    
2385    16. PCRE now gives errors for /[.x.]/ and /[=x=]/ as unsupported POSIX
2386    features, as Perl does. Previously, PCRE gave the warnings only for /[[.x.]]/
2387    and /[[=x=]]/. PCRE now also gives an error for /[:name:]/ because it supports
2388    POSIX classes only within a class (e.g. /[[:alpha:]]/).
2389    
2390    17. Added support for Perl's \C escape. This matches one byte, even in UTF8
2391    mode. Unlike ".", it always matches newline, whatever the setting of
2392    PCRE_DOTALL. However, PCRE does not permit \C to appear in lookbehind
2393    assertions. Perl allows it, but it doesn't (in general) work because it can't
2394    calculate the length of the lookbehind. At least, that's the case for Perl
2395    5.8.0 - I've been told they are going to document that it doesn't work in
2396    future.
2397    
2398    18. Added an error diagnosis for escapes that PCRE does not support: these are
2399    \L, \l, \N, \P, \p, \U, \u, and \X.
2400    
2401    19. Although correctly diagnosing a missing ']' in a character class, PCRE was
2402    reading past the end of the pattern in cases such as /[abcd/.
2403    
2404    20. PCRE was getting more memory than necessary for patterns with classes that
2405    contained both POSIX named classes and other characters, e.g. /[[:space:]abc/.
2406    
2407    21. Added some code, conditional on #ifdef VPCOMPAT, to make life easier for
2408    compiling PCRE for use with Virtual Pascal.
2409    
2410    22. Small fix to the Makefile to make it work properly if the build is done
2411    outside the source tree.
2412    
2413    23. Added a new extension: a condition to go with recursion. If a conditional
2414    subpattern starts with (?(R) the "true" branch is used if recursion has
2415    happened, whereas the "false" branch is used only at the top level.
2416    
2417    24. When there was a very long string of literal characters (over 255 bytes
2418    without UTF support, over 250 bytes with UTF support), the computation of how
2419    much memory was required could be incorrect, leading to segfaults or other
2420    strange effects.
2421    
2422    25. PCRE was incorrectly assuming anchoring (either to start of subject or to
2423    start of line for a non-DOTALL pattern) when a pattern started with (.*) and
2424    there was a subsequent back reference to those brackets. This meant that, for
2425    example, /(.*)\d+\1/ failed to match "abc123bc". Unfortunately, it isn't
2426    possible to check for precisely this case. All we can do is abandon the
2427    optimization if .* occurs inside capturing brackets when there are any back
2428    references whatsoever. (See below for a better fix that came later.)
2429    
2430    26. The handling of the optimization for finding the first character of a
2431    non-anchored pattern, and for finding a character that is required later in the
2432    match were failing in some cases. This didn't break the matching; it just
2433    failed to optimize when it could. The way this is done has been re-implemented.
2434    
2435    27. Fixed typo in error message for invalid (?R item (it said "(?p").
2436    
2437    28. Added a new feature that provides some of the functionality that Perl
2438    provides with (?{...}). The facility is termed a "callout". The way it is done
2439    in PCRE is for the caller to provide an optional function, by setting
2440    pcre_callout to its entry point. Like pcre_malloc and pcre_free, this is a
2441    global variable. By default it is unset, which disables all calling out. To get
2442    the function called, the regex must include (?C) at appropriate points. This
2443    is, in fact, equivalent to (?C0), and any number <= 255 may be given with (?C).
2444    This provides a means of identifying different callout points. When PCRE
2445    reaches such a point in the regex, if pcre_callout has been set, the external
2446    function is called. It is provided with data in a structure called
2447    pcre_callout_block, which is defined in pcre.h. If the function returns 0,
2448    matching continues; if it returns a non-zero value, the match at the current
2449    point fails. However, backtracking will occur if possible. [This was changed
2450    later and other features added - see item 49 below.]
2451    
2452    29. pcretest is upgraded to test the callout functionality. It provides a
2453    callout function that displays information. By default, it shows the start of
2454    the match and the current position in the text. There are some new data escapes
2455    to vary what happens:
2456    
2457        \C+         in addition, show current contents of captured substrings
2458        \C-         do not supply a callout function
2459        \C!n        return 1 when callout number n is reached
2460        \C!n!m      return 1 when callout number n is reached for the mth time
2461    
2462    30. If pcregrep was called with the -l option and just a single file name, it
2463    output "<stdin>" if a match was found, instead of the file name.
2464    
2465    31. Improve the efficiency of the POSIX API to PCRE. If the number of capturing
2466    slots is less than POSIX_MALLOC_THRESHOLD, use a block on the stack to pass to
2467    pcre_exec(). This saves a malloc/free per call. The default value of
2468    POSIX_MALLOC_THRESHOLD is 10; it can be changed by --with-posix-malloc-threshold
2469    when configuring.
2470    
2471    32. The default maximum size of a compiled pattern is 64K. There have been a
2472    few cases of people hitting this limit. The code now uses macros to handle the
2473    storing of links as offsets within the compiled pattern. It defaults to 2-byte
2474    links, but this can be changed to 3 or 4 bytes by --with-link-size when
2475    configuring. Tests 2 and 5 work only with 2-byte links because they output
2476    debugging information about compiled patterns.
2477    
2478    33. Internal code re-arrangements:
2479    
2480    (a) Moved the debugging function for printing out a compiled regex into
2481        its own source file (printint.c) and used #include to pull it into
2482        pcretest.c and, when DEBUG is defined, into pcre.c, instead of having two
2483        separate copies.
2484    
2485    (b) Defined the list of op-code names for debugging as a macro in
2486        internal.h so that it is next to the definition of the opcodes.
2487    
2488    (c) Defined a table of op-code lengths for simpler skipping along compiled
2489        code. This is again a macro in internal.h so that it is next to the
2490        definition of the opcodes.
2491    
2492    34. Added support for recursive calls to individual subpatterns, along the
2493    lines of Robin Houston's patch (but implemented somewhat differently).
2494    
2495    35. Further mods to the Makefile to help Win32. Also, added code to pcregrep to
2496    allow it to read and process whole directories in Win32. This code was
2497    contributed by Lionel Fourquaux; it has not been tested by me.
2498    
2499    36. Added support for named subpatterns. The Python syntax (?P<name>...) is
2500    used to name a group. Names consist of alphanumerics and underscores, and must
2501    be unique. Back references use the syntax (?P=name) and recursive calls use
2502    (?P>name) which is a PCRE extension to the Python extension. Groups still have
2503    numbers. The function pcre_fullinfo() can be used after compilation to extract
2504    a name/number map. There are three relevant calls:
2505    
2506      PCRE_INFO_NAMEENTRYSIZE        yields the size of each entry in the map
2507      PCRE_INFO_NAMECOUNT            yields the number of entries
2508      PCRE_INFO_NAMETABLE            yields a pointer to the map.
2509    
2510    The map is a vector of fixed-size entries. The size of each entry depends on
2511    the length of the longest name used. The first two bytes of each entry are the
2512    group number, most significant byte first. There follows the corresponding
2513    name, zero terminated. The names are in alphabetical order.
2514    
2515    37. Make the maximum literal string in the compiled code 250 for the non-UTF-8
2516    case instead of 255. Making it the same both with and without UTF-8 support
2517    means that the same test output works with both.
2518    
2519    38. There was a case of malloc(0) in the POSIX testing code in pcretest. Avoid
2520    calling malloc() with a zero argument.
2521    
2522    39. Change 25 above had to resort to a heavy-handed test for the .* anchoring
2523    optimization. I've improved things by keeping a bitmap of backreferences with
2524    numbers 1-31 so that if .* occurs inside capturing brackets that are not in
2525    fact referenced, the optimization can be applied. It is unlikely that a
2526    relevant occurrence of .* (i.e. one which might indicate anchoring or forcing
2527    the match to follow \n) will appear inside brackets with a number greater than
2528    31, but if it does, any back reference > 31 suppresses the optimization.
2529    
2530    40. Added a new compile-time option PCRE_NO_AUTO_CAPTURE. This has the effect
2531    of disabling numbered capturing parentheses. Any opening parenthesis that is
2532    not followed by ? behaves as if it were followed by ?: but named parentheses
2533    can still be used for capturing (and they will acquire numbers in the usual
2534    way).
2535    
2536    41. Redesigned the return codes from the match() function into yes/no/error so
2537    that errors can be passed back from deep inside the nested calls. A malloc
2538    failure while inside a recursive subpattern call now causes the
2539    PCRE_ERROR_NOMEMORY return instead of quietly going wrong.
2540    
2541    42. It is now possible to set a limit on the number of times the match()
2542    function is called in a call to pcre_exec(). This facility makes it possible to
2543    limit the amount of recursion and backtracking, though not in a directly
2544    obvious way, because the match() function is used in a number of different
2545    circumstances. The count starts from zero for each position in the subject
2546    string (for non-anchored patterns). The default limit is, for compatibility, a
2547    large number, namely 10 000 000. You can change this in two ways:
2548    
2549    (a) When configuring PCRE before making, you can use --with-match-limit=n
2550        to set a default value for the compiled library.
2551    
2552    (b) For each call to pcre_exec(), you can pass a pcre_extra block in which
2553        a different value is set. See 45 below.
2554    
2555    If the limit is exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT.
2556    
2557    43. Added a new function pcre_config(int, void *) to enable run-time extraction
2558    of things that can be changed at compile time. The first argument specifies
2559    what is wanted and the second points to where the information is to be placed.
2560    The current list of available information is:
2561    
2562      PCRE_CONFIG_UTF8
2563    
2564    The output is an integer that is set to one if UTF-8 support is available;
2565    otherwise it is set to zero.
2566    
2567      PCRE_CONFIG_NEWLINE
2568    
2569    The output is an integer that it set to the value of the code that is used for
2570    newline. It is either LF (10) or CR (13).
2571    
2572      PCRE_CONFIG_LINK_SIZE
2573    
2574    The output is an integer that contains the number of bytes used for internal
2575    linkage in compiled expressions. The value is 2, 3, or 4. See item 32 above.
2576    
2577      PCRE_CONFIG_POSIX_MALLOC_THRESHOLD
2578    
2579    The output is an integer that contains the threshold above which the POSIX
2580    interface uses malloc() for output vectors. See item 31 above.
2581    
2582      PCRE_CONFIG_MATCH_LIMIT
2583    
2584    The output is an unsigned integer that contains the default limit of the number
2585    of match() calls in a pcre_exec() execution. See 42 above.
2586    
2587    44. pcretest has been upgraded by the addition of the -C option. This causes it
2588    to extract all the available output from the new pcre_config() function, and to
2589    output it. The program then exits immediately.
2590    
2591    45. A need has arisen to pass over additional data with calls to pcre_exec() in
2592    order to support additional features. One way would have been to define
2593    pcre_exec2() (for example) with extra arguments, but this would not have been
2594    extensible, and would also have required all calls to the original function to
2595    be mapped to the new one. Instead, I have chosen to extend the mechanism that
2596    is used for passing in "extra" data from pcre_study().
2597    
2598    The pcre_extra structure is now exposed and defined in pcre.h. It currently
2599    contains the following fields:
2600    
2601      flags         a bitmap indicating which of the following fields are set
2602      study_data    opaque data from pcre_study()
2603      match_limit   a way of specifying a limit on match() calls for a specific
2604                      call to pcre_exec()
2605      callout_data  data for callouts (see 49 below)
2606    
2607    The flag bits are also defined in pcre.h, and are
2608    
2609      PCRE_EXTRA_STUDY_DATA
2610      PCRE_EXTRA_MATCH_LIMIT
2611      PCRE_EXTRA_CALLOUT_DATA
2612    
2613    The pcre_study() function now returns one of these new pcre_extra blocks, with
2614    the actual study data pointed to by the study_data field, and the
2615    PCRE_EXTRA_STUDY_DATA flag set. This can be passed directly to pcre_exec() as
2616    before. That is, this change is entirely upwards-compatible and requires no
2617    change to existing code.
2618    
2619    If you want to pass in additional data to pcre_exec(), you can either place it
2620    in a pcre_extra block provided by pcre_study(), or create your own pcre_extra
2621    block.
2622    
2623    46. pcretest has been extended to test the PCRE_EXTRA_MATCH_LIMIT feature. If a
2624    data string contains the escape sequence \M, pcretest calls pcre_exec() several
2625    times with different match limits, until it finds the minimum value needed for
2626    pcre_exec() to complete. The value is then output. This can be instructive; for
2627    most simple matches the number is quite small, but for pathological cases it
2628    gets very large very quickly.
2629    
2630    47. There's a new option for pcre_fullinfo() called PCRE_INFO_STUDYSIZE. It
2631    returns the size of the data block pointed to by the study_data field in a
2632    pcre_extra block, that is, the value that was passed as the argument to
2633    pcre_malloc() when PCRE was getting memory in which to place the information
2634    created by pcre_study(). The fourth argument should point to a size_t variable.
2635    pcretest has been extended so that this information is shown after a successful
2636    pcre_study() call when information about the compiled regex is being displayed.
2637    
2638    48. Cosmetic change to Makefile: there's no need to have / after $(DESTDIR)
2639    because what follows is always an absolute path. (Later: it turns out that this
2640    is more than cosmetic for MinGW, because it doesn't like empty path
2641    components.)
2642    
2643    49. Some changes have been made to the callout feature (see 28 above):
2644    
2645    (i)  A callout function now has three choices for what it returns:
2646    
2647           0  =>  success, carry on matching
2648         > 0  =>  failure at this point, but backtrack if possible
2649         < 0  =>  serious error, return this value from pcre_exec()
2650    
2651         Negative values should normally be chosen from the set of PCRE_ERROR_xxx
2652         values. In particular, returning PCRE_ERROR_NOMATCH forces a standard
2653         "match failed" error. The error number PCRE_ERROR_CALLOUT is reserved for
2654         use by callout functions. It will never be used by PCRE itself.
2655    
2656    (ii) The pcre_extra structure (see 45 above) has a void * field called
2657         callout_data, with corresponding flag bit PCRE_EXTRA_CALLOUT_DATA. The
2658         pcre_callout_block structure has a field of the same name. The contents of
2659         the field passed in the pcre_extra structure are passed to the callout
2660         function in the corresponding field in the callout block. This makes it
2661         easier to use the same callout-containing regex from multiple threads. For
2662         testing, the pcretest program has a new data escape
2663    
2664           \C*n        pass the number n (may be negative) as callout_data
2665    
2666         If the callout function in pcretest receives a non-zero value as
2667         callout_data, it returns that value.
2668    
2669    50. Makefile wasn't handling CFLAGS properly when compiling dftables. Also,
2670    there were some redundant $(CFLAGS) in commands that are now specified as
2671    $(LINK), which already includes $(CFLAGS).
2672    
2673    51. Extensions to UTF-8 support are listed below. These all apply when (a) PCRE
2674    has been compiled with UTF-8 support *and* pcre_compile() has been compiled
2675    with the PCRE_UTF8 flag. Patterns that are compiled without that flag assume
2676    one-byte characters throughout. Note that case-insensitive matching applies
2677    only to characters whose values are less than 256. PCRE doesn't support the
2678    notion of cases for higher-valued characters.
2679    
2680    (i)   A character class whose characters are all within 0-255 is handled as
2681          a bit map, and the map is inverted for negative classes. Previously, a
2682          character > 255 always failed to match such a class; however it should
2683          match if the class was a negative one (e.g. [^ab]). This has been fixed.
2684    
2685    (ii)  A negated character class with a single character < 255 is coded as
2686          "not this character" (OP_NOT). This wasn't working properly when the test
2687          character was multibyte, either singly or repeated.
2688    
2689    (iii) Repeats of multibyte characters are now handled correctly in UTF-8
2690          mode, for example: \x{100}{2,3}.
2691    
2692    (iv)  The character escapes \b, \B, \d, \D, \s, \S, \w, and \W (either
2693          singly or repeated) now correctly test multibyte characters. However,
2694          PCRE doesn't recognize any characters with values greater than 255 as
2695          digits, spaces, or word characters. Such characters always match \D, \S,
2696          and \W, and never match \d, \s, or \w.
2697    
2698    (v)   Classes may now contain characters and character ranges with values
2699          greater than 255. For example: [ab\x{100}-\x{400}].
2700    
2701    (vi)  pcregrep now has a --utf-8 option (synonym -u) which makes it call
2702          PCRE in UTF-8 mode.
2703    
2704    52. The info request value PCRE_INFO_FIRSTCHAR has been renamed
2705    PCRE_INFO_FIRSTBYTE because it is a byte value. However, the old name is
2706    retained for backwards compatibility. (Note that LASTLITERAL is also a byte
2707    value.)
2708    
2709    53. The single man page has become too large. I have therefore split it up into
2710    a number of separate man pages. These also give rise to individual HTML pages;
2711    these are now put in a separate directory, and there is an index.html page that
2712    lists them all. Some hyperlinking between the pages has been installed.
2713    
2714    54. Added convenience functions for handling named capturing parentheses.
2715    
2716    55. Unknown escapes inside character classes (e.g. [\M]) and escapes that
2717    aren't interpreted therein (e.g. [\C]) are literals in Perl. This is now also
2718    true in PCRE, except when the PCRE_EXTENDED option is set, in which case they
2719    are faulted.
2720    
2721    56. Introduced HOST_CC and HOST_CFLAGS which can be set in the environment when
2722    calling configure. These values are used when compiling the dftables.c program
2723    which is run to generate the source of the default character tables. They
2724    default to the values of CC and CFLAGS. If you are cross-compiling PCRE,
2725    you will need to set these values.
2726    
2727    57. Updated the building process for Windows DLL, as provided by Fred Cox.
2728    
2729    
2730    Version 3.9 02-Jan-02
2731    ---------------------
2732    
2733    1. A bit of extraneous text had somehow crept into the pcregrep documentation.
2734    
2735    2. If --disable-static was given, the building process failed when trying to
2736    build pcretest and pcregrep. (For some reason it was using libtool to compile
2737    them, which is not right, as they aren't part of the library.)
2738    
2739    
2740    Version 3.8 18-Dec-01
2741    ---------------------
2742    
2743    1. The experimental UTF-8 code was completely screwed up. It was packing the
2744    bytes in the wrong order. How dumb can you get?
2745    
2746    
2747    Version 3.7 29-Oct-01
2748    ---------------------
2749    
2750    1. In updating pcretest to check change 1 of version 3.6, I screwed up.
2751    This caused pcretest, when used on the test data, to segfault. Unfortunately,
2752    this didn't happen under Solaris 8, where I normally test things.
2753    
2754    2. The Makefile had to be changed to make it work on BSD systems, where 'make'
2755    doesn't seem to recognize that ./xxx and xxx are the same file. (This entry
2756    isn't in ChangeLog distributed with 3.7 because I forgot when I hastily made
2757    this fix an hour or so after the initial 3.7 release.)
2758    
2759    
2760    Version 3.6 23-Oct-01
2761    ---------------------
2762    
2763    1. Crashed with /(sens|respons)e and \1ibility/ and "sense and sensibility" if
2764    offsets passed as NULL with zero offset count.
2765    
2766    2. The config.guess and config.sub files had not been updated when I moved to
2767    the latest autoconf.
2768    
2769    
2770    Version 3.5 15-Aug-01
2771    ---------------------
2772    
2773    1. Added some missing #if !defined NOPOSIX conditionals in pcretest.c that
2774    had been forgotten.
2775    
2776    2. By using declared but undefined structures, we can avoid using "void"
2777    definitions in pcre.h while keeping the internal definitions of the structures
2778    private.
2779    
2780    3. The distribution is now built using autoconf 2.50 and libtool 1.4. From a
2781    user point of view, this means that both static and shared libraries are built
2782    by default, but this can be individually controlled. More of the work of
2783    handling this static/shared cases is now inside libtool instead of PCRE's make
2784    file.
2785    
2786    4. The pcretest utility is now installed along with pcregrep because it is
2787    useful for users (to test regexs) and by doing this, it automatically gets
2788    relinked by libtool. The documentation has been turned into a man page, so
2789    there are now .1, .txt, and .html versions in /doc.
2790    
2791    5. Upgrades to pcregrep:
2792       (i)   Added long-form option names like gnu grep.
2793       (ii)  Added --help to list all options with an explanatory phrase.
2794       (iii) Added -r, --recursive to recurse into sub-directories.
2795       (iv)  Added -f, --file to read patterns from a file.
2796    
2797    6. pcre_exec() was referring to its "code" argument before testing that
2798    argument for NULL (and giving an error if it was NULL).
2799    
2800    7. Upgraded Makefile.in to allow for compiling in a different directory from
2801    the source directory.
2802    
2803    8. Tiny buglet in pcretest: when pcre_fullinfo() was called to retrieve the
2804    options bits, the pointer it was passed was to an int instead of to an unsigned
2805    long int. This mattered only on 64-bit systems.
2806    
2807    9. Fixed typo (3.4/1) in pcre.h again. Sigh. I had changed pcre.h (which is
2808    generated) instead of pcre.in, which it its source. Also made the same change
2809    in several of the .c files.
2810    
2811    10. A new release of gcc defines printf() as a macro, which broke pcretest
2812    because it had an ifdef in the middle of a string argument for printf(). Fixed
2813    by using separate calls to printf().
2814    
2815    11. Added --enable-newline-is-cr and --enable-newline-is-lf to the configure
2816    script, to force use of CR or LF instead of \n in the source. On non-Unix
2817    systems, the value can be set in config.h.
2818    
2819    12. The limit of 200 on non-capturing parentheses is a _nesting_ limit, not an
2820    absolute limit. Changed the text of the error message to make this clear, and
2821    likewise updated the man page.
2822    
2823    13. The limit of 99 on the number of capturing subpatterns has been removed.
2824    The new limit is 65535, which I hope will not be a "real" limit.
2825    
2826    
2827    Version 3.4 22-Aug-00
2828    ---------------------
2829    
2830    1. Fixed typo in pcre.h: unsigned const char * changed to const unsigned char *.
2831    
2832    2. Diagnose condition (?(0) as an error instead of crashing on matching.
2833    
2834    
2835    Version 3.3 01-Aug-00
2836    ---------------------
2837    
2838    1. If an octal character was given, but the value was greater than \377, it
2839    was not getting masked to the least significant bits, as documented. This could
2840    lead to crashes in some systems.
2841    
2842    2. Perl 5.6 (if not earlier versions) accepts classes like [a-\d] and treats
2843    the hyphen as a literal. PCRE used to give an error; it now behaves like Perl.
2844    
2845    3. Added the functions pcre_free_substring() and pcre_free_substring_list().
2846    These just pass their arguments on to (pcre_free)(), but they are provided
2847    because some uses of PCRE bind it to non-C systems that can call its functions,
2848    but cannot call free() or pcre_free() directly.
2849    
2850    4. Add "make test" as a synonym for "make check". Corrected some comments in
2851    the Makefile.
2852    
2853    5. Add $(DESTDIR)/ in front of all the paths in the "install" target in the
2854    Makefile.
2855    
2856    6. Changed the name of pgrep to pcregrep, because Solaris has introduced a
2857    command called pgrep for grepping around the active processes.
2858    
2859    7. Added the beginnings of support for UTF-8 character strings.
2860    
2861    8. Arranged for the Makefile to pass over the settings of CC, CFLAGS, and
2862    RANLIB to ./ltconfig so that they are used by libtool. I think these are all
2863    the relevant ones. (AR is not passed because ./ltconfig does its own figuring
2864    out for the ar command.)
2865    
2866    
2867    Version 3.2 12-May-00
2868    ---------------------
2869    
2870    This is purely a bug fixing release.
2871    
2872    1. If the pattern /((Z)+|A)*/ was matched agained ZABCDEFG it matched Z instead
2873    of ZA. This was just one example of several cases that could provoke this bug,
2874    which was introduced by change 9 of version 2.00. The code for breaking
2875    infinite loops after an iteration that matches an empty string was't working
2876    correctly.
2877    
2878    2. The pcretest program was not imitating Perl correctly for the pattern /a*/g
2879    when matched against abbab (for example). After matching an empty string, it
2880    wasn't forcing anchoring when setting PCRE_NOTEMPTY for the next attempt; this
2881    caused it to match further down the string than it should.
2882    
2883    3. The code contained an inclusion of sys/types.h. It isn't clear why this
2884    was there because it doesn't seem to be needed, and it causes trouble on some
2885    systems, as it is not a Standard C header. It has been removed.
2886    
2887    4. Made 4 silly changes to the source to avoid stupid compiler warnings that
2888    were reported on the Macintosh. The changes were from
2889    
2890      while ((c = *(++ptr)) != 0 && c != '\n');
2891    to
2892      while ((c = *(++ptr)) != 0 && c != '\n') ;
2893    
2894    Totally extraordinary, but if that's what it takes...
2895    
2896    5. PCRE is being used in one environment where neither memmove() nor bcopy() is
2897    available. Added HAVE_BCOPY and an autoconf test for it; if neither
2898    HAVE_MEMMOVE nor HAVE_BCOPY is set, use a built-in emulation function which
2899    assumes the way PCRE uses memmove() (always moving upwards).
2900    
2901    6. PCRE is being used in one environment where strchr() is not available. There
2902    was only one use in pcre.c, and writing it out to avoid strchr() probably gives
2903    faster code anyway.
2904    
2905    
2906    Version 3.1 09-Feb-00
2907    ---------------------
2908    
2909    The only change in this release is the fixing of some bugs in Makefile.in for
2910    the "install" target:
2911    
2912    (1) It was failing to install pcreposix.h.
2913    
2914    (2) It was overwriting the pcre.3 man page with the pcreposix.3 man page.
2915    
2916    
2917    Version 3.0 01-Feb-00
2918    ---------------------
2919    
2920    1. Add support for the /+ modifier to perltest (to output $` like it does in
2921    pcretest).
2922    
2923    2. Add support for the /g modifier to perltest.
2924    
2925    3. Fix pcretest so that it behaves even more like Perl for /g when the pattern
2926    matches null strings.
2927    
2928    4. Fix perltest so that it doesn't do unwanted things when fed an empty
2929    pattern. Perl treats empty patterns specially - it reuses the most recent
2930    pattern, which is not what we want. Replace // by /(?#)/ in order to avoid this
2931    effect.
2932    
2933    5. The POSIX interface was broken in that it was just handing over the POSIX
2934    captured string vector to pcre_exec(), but (since release 2.00) PCRE has
2935    required a bigger vector, with some working space on the end. This means that
2936    the POSIX wrapper now has to get and free some memory, and copy the results.
2937    
2938    6. Added some simple autoconf support, placing the test data and the
2939    documentation in separate directories, re-organizing some of the
2940    information files, and making it build pcre-config (a GNU standard). Also added
2941    libtool support for building PCRE as a shared library, which is now the
2942    default.
2943    
2944    7. Got rid of the leading zero in the definition of PCRE_MINOR because 08 and
2945    09 are not valid octal constants. Single digits will be used for minor values
2946    less than 10.
2947    
2948    8. Defined REG_EXTENDED and REG_NOSUB as zero in the POSIX header, so that
2949    existing programs that set these in the POSIX interface can use PCRE without
2950    modification.
2951    
2952    9. Added a new function, pcre_fullinfo() with an extensible interface. It can
2953    return all that pcre_info() returns, plus additional data. The pcre_info()
2954    function is retained for compatibility, but is considered to be obsolete.
2955    
2956    10. Added experimental recursion feature (?R) to handle one common case that
2957    Perl 5.6 will be able to do with (?p{...}).
2958    
2959    11. Added support for POSIX character classes like [:alpha:], which Perl is
2960    adopting.
2961    
2962    
2963    Version 2.08 31-Aug-99
2964    ----------------------
2965    
2966    1. When startoffset was not zero and the pattern began with ".*", PCRE was not
2967    trying to match at the startoffset position, but instead was moving forward to
2968    the next newline as if a previous match had failed.
2969    
2970    2. pcretest was not making use of PCRE_NOTEMPTY when repeating for /g and /G,
2971    and could get into a loop if a null string was matched other than at the start
2972    of the subject.
2973    
2974    3. Added definitions of PCRE_MAJOR and PCRE_MINOR to pcre.h so the version can
2975    be distinguished at compile time, and for completeness also added PCRE_DATE.
2976    
2977    5. Added Paul Sokolovsky's minor changes to make it easy to compile a Win32 DLL
2978    in GnuWin32 environments.
2979    
2980    
2981    Version 2.07 29-Jul-99
2982    ----------------------
2983    
2984    1. The documentation is now supplied in plain text form and HTML as well as in
2985    the form of man page sources.
2986    
2987    2. C++ compilers don't like assigning (void *) values to other pointer types.
2988    In particular this affects malloc(). Although there is no problem in Standard
2989    C, I've put in casts to keep C++ compilers happy.
2990    
2991    3. Typo on pcretest.c; a cast of (unsigned char *) in the POSIX regexec() call
2992    should be (const char *).
2993    
2994    4. If NOPOSIX is defined, pcretest.c compiles without POSIX support. This may
2995    be useful for non-Unix systems who don't want to bother with the POSIX stuff.
2996    However, I haven't made this a standard facility. The documentation doesn't
2997    mention it, and the Makefile doesn't support it.
2998    
2999    5. The Makefile now contains an "install" target, with editable destinations at
3000    the top of the file. The pcretest program is not installed.
3001    
3002    6. pgrep -V now gives the PCRE version number and date.
3003    
3004    7. Fixed bug: a zero repetition after a literal string (e.g. /abcde{0}/) was
3005    causing the entire string to be ignored, instead of just the last character.
3006    
3007    8. If a pattern like /"([^\\"]+|\\.)*"/ is applied in the normal way to a
3008    non-matching string, it can take a very, very long time, even for strings of
3009    quite modest length, because of the nested recursion. PCRE now does better in
3010    some of these cases. It does this by remembering the last required literal
3011    character in the pattern, and pre-searching the subject to ensure it is present
3012    before running the real match. In other words, it applies a heuristic to detect
3013    some types of certain failure quickly, and in the above example, if presented
3014    with a string that has no trailing " it gives "no match" very quickly.
3015    
3016    9. A new runtime option PCRE_NOTEMPTY causes null string matches to be ignored;
3017    other alternatives are tried instead.
3018    
3019    
3020    Version 2.06 09-Jun-99
3021    ----------------------
3022    
3023    1. Change pcretest's output for amount of store used to show just the code
3024    space, because the remainder (the data block) varies in size between 32-bit and
3025    64-bit systems.
3026    
3027    2. Added an extra argument to pcre_exec() to supply an offset in the subject to
3028    start matching at. This allows lookbehinds to work when searching for multiple
3029    occurrences in a string.
3030    
3031    3. Added additional options to pcretest for testing multiple occurrences:
3032    
3033       /+   outputs the rest of the string that follows a match
3034       /g   loops for multiple occurrences, using the new startoffset argument
3035       /G   loops for multiple occurrences by passing an incremented pointer
3036    
3037    4. PCRE wasn't doing the "first character" optimization for patterns starting
3038    with \b or \B, though it was doing it for other lookbehind assertions. That is,
3039    it wasn't noticing that a match for a pattern such as /\bxyz/ has to start with
3040    the letter 'x'. On long subject strings, this gives a significant speed-up.
3041    
3042    
3043    Version 2.05 21-Apr-99
3044    ----------------------
3045    
3046    1. Changed the type of magic_number from int to long int so that it works
3047    properly on 16-bit systems.
3048    
3049    2. Fixed a bug which caused patterns starting with .* not to work correctly
3050    when the subject string contained newline characters. PCRE was assuming
3051    anchoring for such patterns in all cases, which is not correct because .* will
3052    not pass a newline unless PCRE_DOTALL is set. It now assumes anchoring only if
3053    DOTALL is set at top level; otherwise it knows that patterns starting with .*
3054    must be retried after every newline in the subject.
3055    
3056    
3057    Version 2.04 18-Feb-99
3058    ----------------------
3059    
3060    1. For parenthesized subpatterns with repeats whose minimum was zero, the
3061    computation of the store needed to hold the pattern was incorrect (too large).
3062    If such patterns were nested a few deep, this could multiply and become a real
3063    problem.
3064    
3065    2. Added /M option to pcretest to show the memory requirement of a specific
3066    pattern. Made -m a synonym of -s (which does this globally) for compatibility.
3067    
3068    3. Subpatterns of the form (regex){n,m} (i.e. limited maximum) were being
3069    compiled in such a way that the backtracking after subsequent failure was
3070    pessimal. Something like (a){0,3} was compiled as (a)?(a)?(a)? instead of
3071    ((a)((a)(a)?)?)? with disastrous performance if the maximum was of any size.
3072    
3073    
3074    Version 2.03 02-Feb-99
3075    ----------------------
3076    
3077    1. Fixed typo and small mistake in man page.
3078    
3079    2. Added 4th condition (GPL supersedes if conflict) and created separate
3080    LICENCE file containing the conditions.
3081    
3082    3. Updated pcretest so that patterns such as /abc\/def/ work like they do in
3083    Perl, that is the internal \ allows the delimiter to be included in the
3084    pattern. Locked out the use of \ as a delimiter. If \ immediately follows
3085    the final delimiter, add \ to the end of the pattern (to test the error).
3086    
3087    4. Added the convenience functions for extracting substrings after a successful
3088    match. Updated pcretest to make it able to test these functions.
3089    
3090    
3091    Version 2.02 14-Jan-99
3092    ----------------------
3093    
3094    1. Initialized the working variables associated with each extraction so that
3095    their saving and restoring doesn't refer to uninitialized store.
3096    
3097    2. Put dummy code into study.c in order to trick the optimizer of the IBM C
3098    compiler for OS/2 into generating correct code. Apparently IBM isn't going to
3099    fix the problem.
3100    
3101    3. Pcretest: the timing code wasn't using LOOPREPEAT for timing execution
3102    calls, and wasn't printing the correct value for compiling calls. Increased the
3103    default value of LOOPREPEAT, and the number of significant figures in the
3104    times.
3105    
3106    4. Changed "/bin/rm" in the Makefile to "-rm" so it works on Windows NT.
3107    
3108    5. Renamed "deftables" as "dftables" to get it down to 8 characters, to avoid
3109    a building problem on Windows NT with a FAT file system.
3110    
3111    
3112    Version 2.01 21-Oct-98
3113    ----------------------
3114    
3115    1. Changed the API for pcre_compile() to allow for the provision of a pointer
3116    to character tables built by pcre_maketables() in the current locale. If NULL
3117    is passed, the default tables are used.
3118    
3119    
3120    Version 2.00 24-Sep-98
3121    ----------------------
3122    
3123    1. Since the (>?) facility is in Perl 5.005, don't require PCRE_EXTRA to enable
3124    it any more.
3125    
3126    2. Allow quantification of (?>) groups, and make it work correctly.
3127    
3128    3. The first character computation wasn't working for (?>) groups.
3129    
3130    4. Correct the implementation of \Z (it is permitted to match on the \n at the
3131    end of the subject) and add 5.005's \z, which really does match only at the
3132    very end of the subject.
3133    
3134    5. Remove the \X "cut" facility; Perl doesn't have it, and (?> is neater.
3135    
3136    6. Remove the ability to specify CASELESS, MULTILINE, DOTALL, and
3137    DOLLAR_END_ONLY at runtime, to make it possible to implement the Perl 5.005
3138    localized options. All options to pcre_study() were also removed.
3139    
3140    7. Add other new features from 5.005:
3141    
3142       $(?<=           positive lookbehind
3143       $(?<!           negative lookbehind
3144       (?imsx-imsx)    added the unsetting capability
3145                       such a setting is global if at outer level; local otherwise
3146       (?imsx-imsx:)   non-capturing groups with option setting
3147       (?(cond)re|re)  conditional pattern matching
3148    
3149       A backreference to itself in a repeated group matches the previous
3150       captured string.
3151    
3152    8. General tidying up of studying (both automatic and via "study")
3153    consequential on the addition of new assertions.
3154    
3155    9. As in 5.005, unlimited repeated groups that could match an empty substring
3156    are no longer faulted at compile time. Instead, the loop is forcibly broken at
3157    runtime if any iteration does actually match an empty substring.
3158    
3159    10. Include the RunTest script in the distribution.
3160    
3161    11. Added tests from the Perl 5.005_02 distribution. This showed up a few
3162    discrepancies, some of which were old and were also with respect to 5.004. They
3163    have now been fixed.
3164    
3165    
3166    Version 1.09 28-Apr-98
3167    ----------------------
3168    
3169    1. A negated single character class followed by a quantifier with a minimum
3170    value of one (e.g.  [^x]{1,6}  ) was not compiled correctly. This could lead to
3171    program crashes, or just wrong answers. This did not apply to negated classes
3172    containing more than one character, or to minima other than one.
3173    
3174    
3175    Version 1.08 27-Mar-98
3176    ----------------------
3177    
3178    1. Add PCRE_UNGREEDY to invert the greediness of quantifiers.
3179    
3180    2. Add (?U) and (?X) to set PCRE_UNGREEDY and PCRE_EXTRA respectively. The
3181    latter must appear before anything that relies on it in the pattern.
3182    
3183    
3184    Version 1.07 16-Feb-98
3185    ----------------------
3186    
3187    1. A pattern such as /((a)*)*/ was not being diagnosed as in error (unlimited
3188    repeat of a potentially empty string).
3189    
3190    
3191    Version 1.06 23-Jan-98
3192    ----------------------
3193    
3194    1. Added Markus Oberhumer's little patches for C++.
3195    
3196    2. Literal strings longer than 255 characters were broken.
3197    
3198    
3199  Version 1.05 23-Dec-97  Version 1.05 23-Dec-97
3200  ----------------------  ----------------------

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