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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
3    
4    Version 6.5 01-Feb-06
5    ---------------------
6    
7     1. When using the partial match feature with pcre_dfa_exec(), it was not
8        anchoring the second and subsequent partial matches at the new starting
9        point. This could lead to incorrect results. For example, with the pattern
10        /1234/, partially matching against "123" and then "a4" gave a match.
11    
12     2. Changes to pcregrep:
13    
14        (a) All non-match returns from pcre_exec() were being treated as failures
15            to match the line. Now, unless the error is PCRE_ERROR_NOMATCH, an
16            error message is output. Some extra information is given for the
17            PCRE_ERROR_MATCHLIMIT and PCRE_ERROR_RECURSIONLIMIT errors, which are
18            probably the only errors that are likely to be caused by users (by
19            specifying a regex that has nested indefinite repeats, for instance).
20            If there are more than 20 of these errors, pcregrep is abandoned.
21    
22        (b) A binary zero was treated as data while matching, but terminated the
23            output line if it was written out. This has been fixed: binary zeroes
24            are now no different to any other data bytes.
25    
26        (c) Whichever of the LC_ALL or LC_CTYPE environment variables is set is
27            used to set a locale for matching. The --locale=xxxx long option has
28            been added (no short equivalent) to specify a locale explicitly on the
29            pcregrep command, overriding the environment variables.
30    
31        (d) When -B was used with -n, some line numbers in the output were one less
32            than they should have been.
33    
34        (e) Added the -o (--only-matching) option.
35    
36        (f) If -A or -C was used with -c (count only), some lines of context were
37            accidentally printed for the final match.
38    
39        (g) Added the -H (--with-filename) option.
40    
41        (h) The combination of options -rh failed to suppress file names for files
42            that were found from directory arguments.
43    
44        (i) Added the -D (--devices) and -d (--directories) options.
45    
46        (j) Added the -F (--fixed-strings) option.
47    
48        (k) Allow "-" to be used as a file name for -f as well as for a data file.
49    
50        (l) Added the --colo(u)r option.
51    
52        (m) Added Jeffrey Friedl's -S testing option, but within #ifdefs so that it
53            is not present by default.
54    
55     3. A nasty bug was discovered in the handling of recursive patterns, that is,
56        items such as (?R) or (?1), when the recursion could match a number of
57        alternatives. If it matched one of the alternatives, but subsequently,
58        outside the recursion, there was a failure, the code tried to back up into
59        the recursion. However, because of the way PCRE is implemented, this is not
60        possible, and the result was an incorrect result from the match.
61    
62        In order to prevent this happening, the specification of recursion has
63        been changed so that all such subpatterns are automatically treated as
64        atomic groups. Thus, for example, (?R) is treated as if it were (?>(?R)).
65    
66     4. I had overlooked the fact that, in some locales, there are characters for
67        which isalpha() is true but neither isupper() nor islower() are true. In
68        the fr_FR locale, for instance, the \xAA and \xBA characters (ordmasculine
69        and ordfeminine) are like this. This affected the treatment of \w and \W
70        when they appeared in character classes, but not when they appeared outside
71        a character class. The bit map for "word" characters is now created
72        separately from the results of isalnum() instead of just taking it from the
73        upper, lower, and digit maps. (Plus the underscore character, of course.)
74    
75     5. The above bug also affected the handling of POSIX character classes such as
76        [[:alpha:]] and [[:alnum:]]. These do not have their own bit maps in PCRE's
77        permanent tables. Instead, the bit maps for such a class were previously
78        created as the appropriate unions of the upper, lower, and digit bitmaps.
79        Now they are created by subtraction from the [[:word:]] class, which has
80        its own bitmap.
81    
82     6. The [[:blank:]] character class matches horizontal, but not vertical space.
83        It is created by subtracting the vertical space characters (\x09, \x0a,
84        \x0b, \x0c) from the [[:space:]] bitmap. Previously, however, the
85        subtraction was done in the overall bitmap for a character class, meaning
86        that a class such as [\x0c[:blank:]] was incorrect because \x0c would not
87        be recognized. This bug has been fixed.
88    
89     7. Patches from the folks at Google:
90    
91          (a) pcrecpp.cc: "to handle a corner case that may or may not happen in
92          real life, but is still worth protecting against".
93    
94          (b) pcrecpp.cc: "corrects a bug when negative radixes are used with
95          regular expressions".
96    
97          (c) pcre_scanner.cc: avoid use of std::count() because not all systems
98          have it.
99    
100          (d) Split off pcrecpparg.h from pcrecpp.h and had the former built by
101          "configure" and the latter not, in order to fix a problem somebody had
102          with compiling the Arg class on HP-UX.
103    
104          (e) Improve the error-handling of the C++ wrapper a little bit.
105    
106          (f) New tests for checking recursion limiting.
107    
108     8. The pcre_memmove() function, which is used only if the environment does not
109        have a standard memmove() function (and is therefore rarely compiled),
110        contained two bugs: (a) use of int instead of size_t, and (b) it was not
111        returning a result (though PCRE never actually uses the result).
112    
113     9. In the POSIX regexec() interface, if nmatch is specified as a ridiculously
114        large number - greater than INT_MAX/(3*sizeof(int)) - REG_ESPACE is
115        returned instead of calling malloc() with an overflowing number that would
116        most likely cause subsequent chaos.
117    
118    10. The debugging option of pcretest was not showing the NO_AUTO_CAPTURE flag.
119    
120    11. The POSIX flag REG_NOSUB is now supported. When a pattern that was compiled
121        with this option is matched, the nmatch and pmatch options of regexec() are
122        ignored.
123    
124    12. Added REG_UTF8 to the POSIX interface. This is not defined by POSIX, but is
125        provided in case anyone wants to the the POSIX interface with UTF-8
126        strings.
127    
128    13. Added CXXLDFLAGS to the Makefile parameters to provide settings only on the
129        C++ linking (needed for some HP-UX environments).
130    
131    14. Avoid compiler warnings in get_ucpname() when compiled without UCP support
132        (unused parameter) and in the pcre_printint() function (omitted "default"
133        switch label when the default is to do nothing).
134    
135    15. Added some code to make it possible, when PCRE is compiled as a C++
136        library, to replace subject pointers for pcre_exec() with a smart pointer
137        class, thus making it possible to process discontinuous strings.
138    
139    16. The two macros PCRE_EXPORT and PCRE_DATA_SCOPE are confusing, and perform
140        much the same function. They were added by different people who were trying
141        to make PCRE easy to compile on non-Unix systems. It has been suggested
142        that PCRE_EXPORT be abolished now that there is more automatic apparatus
143        for compiling on Windows systems. I have therefore replaced it with
144        PCRE_DATA_SCOPE. This is set automatically for Windows; if not set it
145        defaults to "extern" for C or "extern C" for C++, which works fine on
146        Unix-like systems. It is now possible to override the value of PCRE_DATA_
147        SCOPE with something explicit in config.h. In addition:
148    
149        (a) pcreposix.h still had just "extern" instead of either of these macros;
150            I have replaced it with PCRE_DATA_SCOPE.
151    
152        (b) Functions such as _pcre_xclass(), which are internal to the library,
153            but external in the C sense, all had PCRE_EXPORT in their definitions.
154            This is apparently wrong for the Windows case, so I have removed it.
155            (It makes no difference on Unix-like systems.)
156    
157    17. Added a new limit, MATCH_LIMIT_RECURSION, which limits the depth of nesting
158        of recursive calls to match(). This is different to MATCH_LIMIT because
159        that limits the total number of calls to match(), not all of which increase
160        the depth of recursion. Limiting the recursion depth limits the amount of
161        stack (or heap if NO_RECURSE is set) that is used. The default can be set
162        when PCRE is compiled, and changed at run time. A patch from Google adds
163        this functionality to the C++ interface.
164    
165    18. Changes to the handling of Unicode character properties:
166    
167        (a) Updated the table to Unicode 4.1.0.
168    
169        (b) Recognize characters that are not in the table as "Cn" (undefined).
170    
171        (c) I revised the way the table is implemented to a much improved format
172            which includes recognition of ranges. It now supports the ranges that
173            are defined in UnicodeData.txt, and it also amalgamates other
174            characters into ranges. This has reduced the number of entries in the
175            table from around 16,000 to around 3,000, thus reducing its size
176            considerably. I realized I did not need to use a tree structure after
177            all - a binary chop search is just as efficient. Having reduced the
178            number of entries, I extended their size from 6 bytes to 8 bytes to
179            allow for more data.
180    
181        (d) Added support for Unicode script names via properties such as \p{Han}.
182    
183    19. In UTF-8 mode, a backslash followed by a non-Ascii character was not
184        matching that character.
185    
186    20. When matching a repeated Unicode property with a minimum greater than zero,
187        (for example \pL{2,}), PCRE could look past the end of the subject if it
188        reached it while seeking the minimum number of characters. This could
189        happen only if some of the characters were more than one byte long, because
190        there is a check for at least the minimum number of bytes.
191    
192    21. Refactored the implementation of \p and \P so as to be more general, to
193        allow for more different types of property in future. This has changed the
194        compiled form incompatibly. Anybody with saved compiled patterns that use
195        \p or \P will have to recompile them.
196    
197    22. Added "Any" and "L&" to the supported property types.
198    
199    23. Recognize \x{...} as a code point specifier, even when not in UTF-8 mode,
200        but give a compile time error if the value is greater than 0xff.
201    
202    24. The man pages for pcrepartial, pcreprecompile, and pcre_compile2 were
203        accidentally not being installed or uninstalled.
204    
205    25. The pcre.h file was built from pcre.h.in, but the only changes that were
206        made were to insert the current release number. This seemed silly, because
207        it made things harder for people building PCRE on systems that don't run
208        "configure". I have turned pcre.h into a distributed file, no longer built
209        by "configure", with the version identification directly included. There is
210        no longer a pcre.h.in file.
211    
212        However, this change necessitated a change to the pcre-config script as
213        well. It is built from pcre-config.in, and one of the substitutions was the
214        release number. I have updated configure.ac so that ./configure now finds
215        the release number by grepping pcre.h.
216    
217    26. Added the ability to run the tests under valgrind.
218    
219    
220    Version 6.4 05-Sep-05
221    ---------------------
222    
223     1. Change 6.0/10/(l) to pcregrep introduced a bug that caused separator lines
224        "--" to be printed when multiple files were scanned, even when none of the
225        -A, -B, or -C options were used. This is not compatible with Gnu grep, so I
226        consider it to be a bug, and have restored the previous behaviour.
227    
228     2. A couple of code tidies to get rid of compiler warnings.
229    
230     3. The pcretest program used to cheat by referring to symbols in the library
231        whose names begin with _pcre_. These are internal symbols that are not
232        really supposed to be visible externally, and in some environments it is
233        possible to suppress them. The cheating is now confined to including
234        certain files from the library's source, which is a bit cleaner.
235    
236     4. Renamed pcre.in as pcre.h.in to go with pcrecpp.h.in; it also makes the
237        file's purpose clearer.
238    
239     5. Reorganized pcre_ucp_findchar().
240    
241    
242    Version 6.3 15-Aug-05
243    ---------------------
244    
245     1. The file libpcre.pc.in did not have general read permission in the tarball.
246    
247     2. There were some problems when building without C++ support:
248    
249        (a) If C++ support was not built, "make install" and "make test" still
250            tried to test it.
251    
252        (b) There were problems when the value of CXX was explicitly set. Some
253            changes have been made to try to fix these, and ...
254    
255        (c) --disable-cpp can now be used to explicitly disable C++ support.
256    
257        (d) The use of @CPP_OBJ@ directly caused a blank line preceded by a
258            backslash in a target when C++ was disabled. This confuses some
259            versions of "make", apparently. Using an intermediate variable solves
260            this. (Same for CPP_LOBJ.)
261    
262     3. $(LINK_FOR_BUILD) now includes $(CFLAGS_FOR_BUILD) and $(LINK)
263        (non-Windows) now includes $(CFLAGS) because these flags are sometimes
264        necessary on certain architectures.
265    
266     4. Added a setting of -export-symbols-regex to the link command to remove
267        those symbols that are exported in the C sense, but actually are local
268        within the library, and not documented. Their names all begin with
269        "_pcre_". This is not a perfect job, because (a) we have to except some
270        symbols that pcretest ("illegally") uses, and (b) the facility isn't always
271        available (and never for static libraries). I have made a note to try to
272        find a way round (a) in the future.
273    
274    
275    Version 6.2 01-Aug-05
276    ---------------------
277    
278     1. There was no test for integer overflow of quantifier values. A construction
279        such as {1111111111111111} would give undefined results. What is worse, if
280        a minimum quantifier for a parenthesized subpattern overflowed and became
281        negative, the calculation of the memory size went wrong. This could have
282        led to memory overwriting.
283    
284     2. Building PCRE using VPATH was broken. Hopefully it is now fixed.
285    
286     3. Added "b" to the 2nd argument of fopen() in dftables.c, for non-Unix-like
287        operating environments where this matters.
288    
289     4. Applied Giuseppe Maxia's patch to add additional features for controlling
290        PCRE options from within the C++ wrapper.
291    
292     5. Named capturing subpatterns were not being correctly counted when a pattern
293        was compiled. This caused two problems: (a) If there were more than 100
294        such subpatterns, the calculation of the memory needed for the whole
295        compiled pattern went wrong, leading to an overflow error. (b) Numerical
296        back references of the form \12, where the number was greater than 9, were
297        not recognized as back references, even though there were sufficient
298        previous subpatterns.
299    
300     6. Two minor patches to pcrecpp.cc in order to allow it to compile on older
301        versions of gcc, e.g. 2.95.4.
302    
303    
304    Version 6.1 21-Jun-05
305    ---------------------
306    
307     1. There was one reference to the variable "posix" in pcretest.c that was not
308        surrounded by "#if !defined NOPOSIX".
309    
310     2. Make it possible to compile pcretest without DFA support, UTF8 support, or
311        the cross-check on the old pcre_info() function, for the benefit of the
312        cut-down version of PCRE that is currently imported into Exim.
313    
314     3. A (silly) pattern starting with (?i)(?-i) caused an internal space
315        allocation error. I've done the easy fix, which wastes 2 bytes for sensible
316        patterns that start (?i) but I don't think that matters. The use of (?i) is
317        just an example; this all applies to the other options as well.
318    
319     4. Since libtool seems to echo the compile commands it is issuing, the output
320        from "make" can be reduced a bit by putting "@" in front of each libtool
321        compile command.
322    
323     5. Patch from the folks at Google for configure.in to be a bit more thorough
324        in checking for a suitable C++ installation before trying to compile the
325        C++ stuff. This should fix a reported problem when a compiler was present,
326        but no suitable headers.
327    
328     6. The man pages all had just "PCRE" as their title. I have changed them to
329        be the relevant file name. I have also arranged that these names are
330        retained in the file doc/pcre.txt, which is a concatenation in text format
331        of all the man pages except the little individual ones for each function.
332    
333     7. The NON-UNIX-USE file had not been updated for the different set of source
334        files that come with release 6. I also added a few comments about the C++
335        wrapper.
336    
337    
338    Version 6.0 07-Jun-05
339    ---------------------
340    
341     1. Some minor internal re-organization to help with my DFA experiments.
342    
343     2. Some missing #ifdef SUPPORT_UCP conditionals in pcretest and printint that
344        didn't matter for the library itself when fully configured, but did matter
345        when compiling without UCP support, or within Exim, where the ucp files are
346        not imported.
347    
348     3. Refactoring of the library code to split up the various functions into
349        different source modules. The addition of the new DFA matching code (see
350        below) to a single monolithic source would have made it really too
351        unwieldy, quite apart from causing all the code to be include in a
352        statically linked application, when only some functions are used. This is
353        relevant even without the DFA addition now that patterns can be compiled in
354        one application and matched in another.
355    
356        The downside of splitting up is that there have to be some external
357        functions and data tables that are used internally in different modules of
358        the library but which are not part of the API. These have all had their
359        names changed to start with "_pcre_" so that they are unlikely to clash
360        with other external names.
361    
362     4. Added an alternate matching function, pcre_dfa_exec(), which matches using
363        a different (DFA) algorithm. Although it is slower than the original
364        function, it does have some advantages for certain types of matching
365        problem.
366    
367     5. Upgrades to pcretest in order to test the features of pcre_dfa_exec(),
368        including restarting after a partial match.
369    
370     6. A patch for pcregrep that defines INVALID_FILE_ATTRIBUTES if it is not
371        defined when compiling for Windows was sent to me. I have put it into the
372        code, though I have no means of testing or verifying it.
373    
374     7. Added the pcre_refcount() auxiliary function.
375    
376     8. Added the PCRE_FIRSTLINE option. This constrains an unanchored pattern to
377        match before or at the first newline in the subject string. In pcretest,
378        the /f option on a pattern can be used to set this.
379    
380     9. A repeated \w when used in UTF-8 mode with characters greater than 256
381        would behave wrongly. This has been present in PCRE since release 4.0.
382    
383    10. A number of changes to the pcregrep command:
384    
385        (a) Refactored how -x works; insert ^(...)$ instead of setting
386            PCRE_ANCHORED and checking the length, in preparation for adding
387            something similar for -w.
388    
389        (b) Added the -w (match as a word) option.
390    
391        (c) Refactored the way lines are read and buffered so as to have more
392            than one at a time available.
393    
394        (d) Implemented a pcregrep test script.
395    
396        (e) Added the -M (multiline match) option. This allows patterns to match
397            over several lines of the subject. The buffering ensures that at least
398            8K, or the rest of the document (whichever is the shorter) is available
399            for matching (and similarly the previous 8K for lookbehind assertions).
400    
401        (f) Changed the --help output so that it now says
402    
403              -w, --word-regex(p)
404    
405            instead of two lines, one with "regex" and the other with "regexp"
406            because that confused at least one person since the short forms are the
407            same. (This required a bit of code, as the output is generated
408            automatically from a table. It wasn't just a text change.)
409    
410        (g) -- can be used to terminate pcregrep options if the next thing isn't an
411            option but starts with a hyphen. Could be a pattern or a path name
412            starting with a hyphen, for instance.
413    
414        (h) "-" can be given as a file name to represent stdin.
415    
416        (i) When file names are being printed, "(standard input)" is used for
417            the standard input, for compatibility with GNU grep. Previously
418            "<stdin>" was used.
419    
420        (j) The option --label=xxx can be used to supply a name to be used for
421            stdin when file names are being printed. There is no short form.
422    
423        (k) Re-factored the options decoding logic because we are going to add
424            two more options that take data. Such options can now be given in four
425            different ways, e.g. "-fname", "-f name", "--file=name", "--file name".
426    
427        (l) Added the -A, -B, and -C options for requesting that lines of context
428            around matches be printed.
429    
430        (m) Added the -L option to print the names of files that do not contain
431            any matching lines, that is, the complement of -l.
432    
433        (n) The return code is 2 if any file cannot be opened, but pcregrep does
434            continue to scan other files.
435    
436        (o) The -s option was incorrectly implemented. For compatibility with other
437            greps, it now suppresses the error message for a non-existent or non-
438            accessible file (but not the return code). There is a new option called
439            -q that suppresses the output of matching lines, which was what -s was
440            previously doing.
441    
442        (p) Added --include and --exclude options to specify files for inclusion
443            and exclusion when recursing.
444    
445    11. The Makefile was not using the Autoconf-supported LDFLAGS macro properly.
446        Hopefully, it now does.
447    
448    12. Missing cast in pcre_study().
449    
450    13. Added an "uninstall" target to the makefile.
451    
452    14. Replaced "extern" in the function prototypes in Makefile.in with
453        "PCRE_DATA_SCOPE", which defaults to 'extern' or 'extern "C"' in the Unix
454        world, but is set differently for Windows.
455    
456    15. Added a second compiling function called pcre_compile2(). The only
457        difference is that it has an extra argument, which is a pointer to an
458        integer error code. When there is a compile-time failure, this is set
459        non-zero, in addition to the error test pointer being set to point to an
460        error message. The new argument may be NULL if no error number is required
461        (but then you may as well call pcre_compile(), which is now just a
462        wrapper). This facility is provided because some applications need a
463        numeric error indication, but it has also enabled me to tidy up the way
464        compile-time errors are handled in the POSIX wrapper.
465    
466    16. Added VPATH=.libs to the makefile; this should help when building with one
467        prefix path and installing with another. (Or so I'm told by someone who
468        knows more about this stuff than I do.)
469    
470    17. Added a new option, REG_DOTALL, to the POSIX function regcomp(). This
471        passes PCRE_DOTALL to the pcre_compile() function, making the "." character
472        match everything, including newlines. This is not POSIX-compatible, but
473        somebody wanted the feature. From pcretest it can be activated by using
474        both the P and the s flags.
475    
476    18. AC_PROG_LIBTOOL appeared twice in Makefile.in. Removed one.
477    
478    19. libpcre.pc was being incorrectly installed as executable.
479    
480    20. A couple of places in pcretest check for end-of-line by looking for '\n';
481        it now also looks for '\r' so that it will work unmodified on Windows.
482    
483    21. Added Google's contributed C++ wrapper to the distribution.
484    
485    22. Added some untidy missing memory free() calls in pcretest, to keep
486        Electric Fence happy when testing.
487    
488    
489    
490    Version 5.0 13-Sep-04
491    ---------------------
492    
493     1. Internal change: literal characters are no longer packed up into items
494        containing multiple characters in a single byte-string. Each character
495        is now matched using a separate opcode. However, there may be more than one
496        byte in the character in UTF-8 mode.
497    
498     2. The pcre_callout_block structure has two new fields: pattern_position and
499        next_item_length. These contain the offset in the pattern to the next match
500        item, and its length, respectively.
501    
502     3. The PCRE_AUTO_CALLOUT option for pcre_compile() requests the automatic
503        insertion of callouts before each pattern item. Added the /C option to
504        pcretest to make use of this.
505    
506     4. On the advice of a Windows user, the lines
507    
508          #if defined(_WIN32) || defined(WIN32)
509          _setmode( _fileno( stdout ), 0x8000 );
510          #endif  /* defined(_WIN32) || defined(WIN32) */
511    
512        have been added to the source of pcretest. This apparently does useful
513        magic in relation to line terminators.
514    
515     5. Changed "r" and "w" in the calls to fopen() in pcretest to "rb" and "wb"
516        for the benefit of those environments where the "b" makes a difference.
517    
518     6. The icc compiler has the same options as gcc, but "configure" doesn't seem
519        to know about it. I have put a hack into configure.in that adds in code
520        to set GCC=yes if CC=icc. This seems to end up at a point in the
521        generated configure script that is early enough to affect the setting of
522        compiler options, which is what is needed, but I have no means of testing
523        whether it really works. (The user who reported this had patched the
524        generated configure script, which of course I cannot do.)
525    
526        LATER: After change 22 below (new libtool files), the configure script
527        seems to know about icc (and also ecc). Therefore, I have commented out
528        this hack in configure.in.
529    
530     7. Added support for pkg-config (2 patches were sent in).
531    
532     8. Negated POSIX character classes that used a combination of internal tables
533        were completely broken. These were [[:^alpha:]], [[:^alnum:]], and
534        [[:^ascii]]. Typically, they would match almost any characters. The other
535        POSIX classes were not broken in this way.
536    
537     9. Matching the pattern "\b.*?" against "ab cd", starting at offset 1, failed
538        to find the match, as PCRE was deluded into thinking that the match had to
539        start at the start point or following a newline. The same bug applied to
540        patterns with negative forward assertions or any backward assertions
541        preceding ".*" at the start, unless the pattern required a fixed first
542        character. This was a failing pattern: "(?!.bcd).*". The bug is now fixed.
543    
544    10. In UTF-8 mode, when moving forwards in the subject after a failed match
545        starting at the last subject character, bytes beyond the end of the subject
546        string were read.
547    
548    11. Renamed the variable "class" as "classbits" to make life easier for C++
549        users. (Previously there was a macro definition, but it apparently wasn't
550        enough.)
551    
552    12. Added the new field "tables" to the extra data so that tables can be passed
553        in at exec time, or the internal tables can be re-selected. This allows
554        a compiled regex to be saved and re-used at a later time by a different
555        program that might have everything at different addresses.
556    
557    13. Modified the pcre-config script so that, when run on Solaris, it shows a
558        -R library as well as a -L library.
559    
560    14. The debugging options of pcretest (-d on the command line or D on a
561        pattern) showed incorrect output for anything following an extended class
562        that contained multibyte characters and which was followed by a quantifier.
563    
564    15. Added optional support for general category Unicode character properties
565        via the \p, \P, and \X escapes. Unicode property support implies UTF-8
566        support. It adds about 90K to the size of the library. The meanings of the
567        inbuilt class escapes such as \d and \s have NOT been changed.
568    
569    16. Updated pcredemo.c to include calls to free() to release the memory for the
570        compiled pattern.
571    
572    17. The generated file chartables.c was being created in the source directory
573        instead of in the building directory. This caused the build to fail if the
574        source directory was different from the building directory, and was
575        read-only.
576    
577    18. Added some sample Win commands from Mark Tetrode into the NON-UNIX-USE
578        file. No doubt somebody will tell me if they don't make sense... Also added
579        Dan Mooney's comments about building on OpenVMS.
580    
581    19. Added support for partial matching via the PCRE_PARTIAL option for
582        pcre_exec() and the \P data escape in pcretest.
583    
584    20. Extended pcretest with 3 new pattern features:
585    
586        (i)   A pattern option of the form ">rest-of-line" causes pcretest to
587              write the compiled pattern to the file whose name is "rest-of-line".
588              This is a straight binary dump of the data, with the saved pointer to
589              the character tables forced to be NULL. The study data, if any, is
590              written too. After writing, pcretest reads a new pattern.
591    
592        (ii)  If, instead of a pattern, "<rest-of-line" is given, pcretest reads a
593              compiled pattern from the given file. There must not be any
594              occurrences of "<" in the file name (pretty unlikely); if there are,
595              pcretest will instead treat the initial "<" as a pattern delimiter.
596              After reading in the pattern, pcretest goes on to read data lines as
597              usual.
598    
599        (iii) The F pattern option causes pcretest to flip the bytes in the 32-bit
600              and 16-bit fields in a compiled pattern, to simulate a pattern that
601              was compiled on a host of opposite endianness.
602    
603    21. The pcre-exec() function can now cope with patterns that were compiled on
604        hosts of opposite endianness, with this restriction:
605    
606          As for any compiled expression that is saved and used later, the tables
607          pointer field cannot be preserved; the extra_data field in the arguments
608          to pcre_exec() should be used to pass in a tables address if a value
609          other than the default internal tables were used at compile time.
610    
611    22. Calling pcre_exec() with a negative value of the "ovecsize" parameter is
612        now diagnosed as an error. Previously, most of the time, a negative number
613        would have been treated as zero, but if in addition "ovector" was passed as
614        NULL, a crash could occur.
615    
616    23. Updated the files ltmain.sh, config.sub, config.guess, and aclocal.m4 with
617        new versions from the libtool 1.5 distribution (the last one is a copy of
618        a file called libtool.m4). This seems to have fixed the need to patch
619        "configure" to support Darwin 1.3 (which I used to do). However, I still
620        had to patch ltmain.sh to ensure that ${SED} is set (it isn't on my
621        workstation).
622    
623    24. Changed the PCRE licence to be the more standard "BSD" licence.
624    
625    
626    Version 4.5 01-Dec-03
627    ---------------------
628    
629     1. There has been some re-arrangement of the code for the match() function so
630        that it can be compiled in a version that does not call itself recursively.
631        Instead, it keeps those local variables that need separate instances for
632        each "recursion" in a frame on the heap, and gets/frees frames whenever it
633        needs to "recurse". Keeping track of where control must go is done by means
634        of setjmp/longjmp. The whole thing is implemented by a set of macros that
635        hide most of the details from the main code, and operates only if
636        NO_RECURSE is defined while compiling pcre.c. If PCRE is built using the
637        "configure" mechanism, "--disable-stack-for-recursion" turns on this way of
638        operating.
639    
640        To make it easier for callers to provide specially tailored get/free
641        functions for this usage, two new functions, pcre_stack_malloc, and
642        pcre_stack_free, are used. They are always called in strict stacking order,
643        and the size of block requested is always the same.
644    
645        The PCRE_CONFIG_STACKRECURSE info parameter can be used to find out whether
646        PCRE has been compiled to use the stack or the heap for recursion. The
647        -C option of pcretest uses this to show which version is compiled.
648    
649        A new data escape \S, is added to pcretest; it causes the amounts of store
650        obtained and freed by both kinds of malloc/free at match time to be added
651        to the output.
652    
653     2. Changed the locale test to use "fr_FR" instead of "fr" because that's
654        what's available on my current Linux desktop machine.
655    
656     3. When matching a UTF-8 string, the test for a valid string at the start has
657        been extended. If start_offset is not zero, PCRE now checks that it points
658        to a byte that is the start of a UTF-8 character. If not, it returns
659        PCRE_ERROR_BADUTF8_OFFSET (-11). Note: the whole string is still checked;
660        this is necessary because there may be backward assertions in the pattern.
661        When matching the same subject several times, it may save resources to use
662        PCRE_NO_UTF8_CHECK on all but the first call if the string is long.
663    
664     4. The code for checking the validity of UTF-8 strings has been tightened so
665        that it rejects (a) strings containing 0xfe or 0xff bytes and (b) strings
666        containing "overlong sequences".
667    
668     5. Fixed a bug (appearing twice) that I could not find any way of exploiting!
669        I had written "if ((digitab[*p++] && chtab_digit) == 0)" where the "&&"
670        should have been "&", but it just so happened that all the cases this let
671        through by mistake were picked up later in the function.
672    
673     6. I had used a variable called "isblank" - this is a C99 function, causing
674        some compilers to warn. To avoid this, I renamed it (as "blankclass").
675    
676     7. Cosmetic: (a) only output another newline at the end of pcretest if it is
677        prompting; (b) run "./pcretest /dev/null" at the start of the test script
678        so the version is shown; (c) stop "make test" echoing "./RunTest".
679    
680     8. Added patches from David Burgess to enable PCRE to run on EBCDIC systems.
681    
682     9. The prototype for memmove() for systems that don't have it was using
683        size_t, but the inclusion of the header that defines size_t was later. I've
684        moved the #includes for the C headers earlier to avoid this.
685    
686    10. Added some adjustments to the code to make it easier to compiler on certain
687        special systems:
688    
689          (a) Some "const" qualifiers were missing.
690          (b) Added the macro EXPORT before all exported functions; by default this
691              is defined to be empty.
692          (c) Changed the dftables auxiliary program (that builds chartables.c) so
693              that it reads its output file name as an argument instead of writing
694              to the standard output and assuming this can be redirected.
695    
696    11. In UTF-8 mode, if a recursive reference (e.g. (?1)) followed a character
697        class containing characters with values greater than 255, PCRE compilation
698        went into a loop.
699    
700    12. A recursive reference to a subpattern that was within another subpattern
701        that had a minimum quantifier of zero caused PCRE to crash. For example,
702        (x(y(?2))z)? provoked this bug with a subject that got as far as the
703        recursion. If the recursively-called subpattern itself had a zero repeat,
704        that was OK.
705    
706    13. In pcretest, the buffer for reading a data line was set at 30K, but the
707        buffer into which it was copied (for escape processing) was still set at
708        1024, so long lines caused crashes.
709    
710    14. A pattern such as /[ab]{1,3}+/ failed to compile, giving the error
711        "internal error: code overflow...". This applied to any character class
712        that was followed by a possessive quantifier.
713    
714    15. Modified the Makefile to add libpcre.la as a prerequisite for
715        libpcreposix.la because I was told this is needed for a parallel build to
716        work.
717    
718    16. If a pattern that contained .* following optional items at the start was
719        studied, the wrong optimizing data was generated, leading to matching
720        errors. For example, studying /[ab]*.*c/ concluded, erroneously, that any
721        matching string must start with a or b or c. The correct conclusion for
722        this pattern is that a match can start with any character.
723    
724    
725    Version 4.4 13-Aug-03
726    ---------------------
727    
728     1. In UTF-8 mode, a character class containing characters with values between
729        127 and 255 was not handled correctly if the compiled pattern was studied.
730        In fixing this, I have also improved the studying algorithm for such
731        classes (slightly).
732    
733     2. Three internal functions had redundant arguments passed to them. Removal
734        might give a very teeny performance improvement.
735    
736     3. Documentation bug: the value of the capture_top field in a callout is *one
737        more than* the number of the hightest numbered captured substring.
738    
739     4. The Makefile linked pcretest and pcregrep with -lpcre, which could result
740        in incorrectly linking with a previously installed version. They now link
741        explicitly with libpcre.la.
742    
743     5. configure.in no longer needs to recognize Cygwin specially.
744    
745     6. A problem in pcre.in for Windows platforms is fixed.
746    
747     7. If a pattern was successfully studied, and the -d (or /D) flag was given to
748        pcretest, it used to include the size of the study block as part of its
749        output. Unfortunately, the structure contains a field that has a different
750        size on different hardware architectures. This meant that the tests that
751        showed this size failed. As the block is currently always of a fixed size,
752        this information isn't actually particularly useful in pcretest output, so
753        I have just removed it.
754    
755     8. Three pre-processor statements accidentally did not start in column 1.
756        Sadly, there are *still* compilers around that complain, even though
757        standard C has not required this for well over a decade. Sigh.
758    
759     9. In pcretest, the code for checking callouts passed small integers in the
760        callout_data field, which is a void * field. However, some picky compilers
761        complained about the casts involved for this on 64-bit systems. Now
762        pcretest passes the address of the small integer instead, which should get
763        rid of the warnings.
764    
765    10. By default, when in UTF-8 mode, PCRE now checks for valid UTF-8 strings at
766        both compile and run time, and gives an error if an invalid UTF-8 sequence
767        is found. There is a option for disabling this check in cases where the
768        string is known to be correct and/or the maximum performance is wanted.
769    
770    11. In response to a bug report, I changed one line in Makefile.in from
771    
772            -Wl,--out-implib,.libs/lib@WIN_PREFIX@pcreposix.dll.a \
773        to
774            -Wl,--out-implib,.libs/@WIN_PREFIX@libpcreposix.dll.a \
775    
776        to look similar to other lines, but I have no way of telling whether this
777        is the right thing to do, as I do not use Windows. No doubt I'll get told
778        if it's wrong...
779    
780    
781    Version 4.3 21-May-03
782    ---------------------
783    
784    1. Two instances of @WIN_PREFIX@ omitted from the Windows targets in the
785       Makefile.
786    
787    2. Some refactoring to improve the quality of the code:
788    
789       (i)   The utf8_table... variables are now declared "const".
790    
791       (ii)  The code for \cx, which used the "case flipping" table to upper case
792             lower case letters, now just substracts 32. This is ASCII-specific,
793             but the whole concept of \cx is ASCII-specific, so it seems
794             reasonable.
795    
796       (iii) PCRE was using its character types table to recognize decimal and
797             hexadecimal digits in the pattern. This is silly, because it handles
798             only 0-9, a-f, and A-F, but the character types table is locale-
799             specific, which means strange things might happen. A private
800             table is now used for this - though it costs 256 bytes, a table is
801             much faster than multiple explicit tests. Of course, the standard
802             character types table is still used for matching digits in subject
803             strings against \d.
804    
805       (iv)  Strictly, the identifier ESC_t is reserved by POSIX (all identifiers
806             ending in _t are). So I've renamed it as ESC_tee.
807    
808    3. The first argument for regexec() in the POSIX wrapper should have been
809       defined as "const".
810    
811    4. Changed pcretest to use malloc() for its buffers so that they can be
812       Electric Fenced for debugging.
813    
814    5. There were several places in the code where, in UTF-8 mode, PCRE would try
815       to read one or more bytes before the start of the subject string. Often this
816       had no effect on PCRE's behaviour, but in some circumstances it could
817       provoke a segmentation fault.
818    
819    6. A lookbehind at the start of a pattern in UTF-8 mode could also cause PCRE
820       to try to read one or more bytes before the start of the subject string.
821    
822    7. A lookbehind in a pattern matched in non-UTF-8 mode on a PCRE compiled with
823       UTF-8 support could misbehave in various ways if the subject string
824       contained bytes with the 0x80 bit set and the 0x40 bit unset in a lookbehind
825       area. (PCRE was not checking for the UTF-8 mode flag, and trying to move
826       back over UTF-8 characters.)
827    
828    
829    Version 4.2 14-Apr-03
830    ---------------------
831    
832    1. Typo "#if SUPPORT_UTF8" instead of "#ifdef SUPPORT_UTF8" fixed.
833    
834    2. Changes to the building process, supplied by Ronald Landheer-Cieslak
835         [ON_WINDOWS]: new variable, "#" on non-Windows platforms
836         [NOT_ON_WINDOWS]: new variable, "#" on Windows platforms
837         [WIN_PREFIX]: new variable, "cyg" for Cygwin
838         * Makefile.in: use autoconf substitution for OBJEXT, EXEEXT, BUILD_OBJEXT
839           and BUILD_EXEEXT
840         Note: automatic setting of the BUILD variables is not yet working
841         set CPPFLAGS and BUILD_CPPFLAGS (but don't use yet) - should be used at
842           compile-time but not at link-time
843         [LINK]: use for linking executables only
844         make different versions for Windows and non-Windows
845         [LINKLIB]: new variable, copy of UNIX-style LINK, used for linking
846           libraries
847         [LINK_FOR_BUILD]: new variable
848         [OBJEXT]: use throughout
849         [EXEEXT]: use throughout
850         <winshared>: new target
851         <wininstall>: new target
852         <dftables.o>: use native compiler
853         <dftables>: use native linker
854         <install>: handle Windows platform correctly
855         <clean>: ditto
856         <check>: ditto
857         copy DLL to top builddir before testing
858    
859       As part of these changes, -no-undefined was removed again. This was reported
860       to give trouble on HP-UX 11.0, so getting rid of it seems like a good idea
861       in any case.
862    
863    3. Some tidies to get rid of compiler warnings:
864    
865       . In the match_data structure, match_limit was an unsigned long int, whereas
866         match_call_count was an int. I've made them both unsigned long ints.
867    
868       . In pcretest the fact that a const uschar * doesn't automatically cast to
869         a void * provoked a warning.
870    
871       . Turning on some more compiler warnings threw up some "shadow" variables
872         and a few more missing casts.
873    
874    4. If PCRE was complied with UTF-8 support, but called without the PCRE_UTF8
875       option, a class that contained a single character with a value between 128
876       and 255 (e.g. /[\xFF]/) caused PCRE to crash.
877    
878    5. If PCRE was compiled with UTF-8 support, but called without the PCRE_UTF8
879       option, a class that contained several characters, but with at least one
880       whose value was between 128 and 255 caused PCRE to crash.
881    
882    
883    Version 4.1 12-Mar-03
884    ---------------------
885    
886    1. Compiling with gcc -pedantic found a couple of places where casts were
887    needed, and a string in dftables.c that was longer than standard compilers are
888    required to support.
889    
890    2. Compiling with Sun's compiler found a few more places where the code could
891    be tidied up in order to avoid warnings.
892    
893    3. The variables for cross-compiling were called HOST_CC and HOST_CFLAGS; the
894    first of these names is deprecated in the latest Autoconf in favour of the name
895    CC_FOR_BUILD, because "host" is typically used to mean the system on which the
896    compiled code will be run. I can't find a reference for HOST_CFLAGS, but by
897    analogy I have changed it to CFLAGS_FOR_BUILD.
898    
899    4. Added -no-undefined to the linking command in the Makefile, because this is
900    apparently helpful for Windows. To make it work, also added "-L. -lpcre" to the
901    linking step for the pcreposix library.
902    
903    5. PCRE was failing to diagnose the case of two named groups with the same
904    name.
905    
906    6. A problem with one of PCRE's optimizations was discovered. PCRE remembers a
907    literal character that is needed in the subject for a match, and scans along to
908    ensure that it is present before embarking on the full matching process. This
909    saves time in cases of nested unlimited repeats that are never going to match.
910    Problem: the scan can take a lot of time if the subject is very long (e.g.
911    megabytes), thus penalizing straightforward matches. It is now done only if the
912    amount of subject to be scanned is less than 1000 bytes.
913    
914    7. A lesser problem with the same optimization is that it was recording the
915    first character of an anchored pattern as "needed", thus provoking a search
916    right along the subject, even when the first match of the pattern was going to
917    fail. The "needed" character is now not set for anchored patterns, unless it
918    follows something in the pattern that is of non-fixed length. Thus, it still
919    fulfils its original purpose of finding quick non-matches in cases of nested
920    unlimited repeats, but isn't used for simple anchored patterns such as /^abc/.
921    
922    
923    Version 4.0 17-Feb-03
924    ---------------------
925    
926    1. If a comment in an extended regex that started immediately after a meta-item
927    extended to the end of string, PCRE compiled incorrect data. This could lead to
928    all kinds of weird effects. Example: /#/ was bad; /()#/ was bad; /a#/ was not.
929    
930    2. Moved to autoconf 2.53 and libtool 1.4.2.
931    
932    3. Perl 5.8 no longer needs "use utf8" for doing UTF-8 things. Consequently,
933    the special perltest8 script is no longer needed - all the tests can be run
934    from a single perltest script.
935    
936    4. From 5.004, Perl has not included the VT character (0x0b) in the set defined
937    by \s. It has now been removed in PCRE. This means it isn't recognized as
938    whitespace in /x regexes too, which is the same as Perl. Note that the POSIX
939    class [:space:] *does* include VT, thereby creating a mess.
940    
941    5. Added the class [:blank:] (a GNU extension from Perl 5.8) to match only
942    space and tab.
943    
944    6. Perl 5.005 was a long time ago. It's time to amalgamate the tests that use
945    its new features into the main test script, reducing the number of scripts.
946    
947    7. Perl 5.8 has changed the meaning of patterns like /a(?i)b/. Earlier versions
948    were backward compatible, and made the (?i) apply to the whole pattern, as if
949    /i were given. Now it behaves more logically, and applies the option setting
950    only to what follows. PCRE has been changed to follow suit. However, if it
951    finds options settings right at the start of the pattern, it extracts them into
952    the global options, as before. Thus, they show up in the info data.
953    
954    8. Added support for the \Q...\E escape sequence. Characters in between are
955    treated as literals. This is slightly different from Perl in that $ and @ are
956    also handled as literals inside the quotes. In Perl, they will cause variable
957    interpolation. Note the following examples:
958    
959        Pattern            PCRE matches      Perl matches
960    
961        \Qabc$xyz\E        abc$xyz           abc followed by the contents of $xyz
962        \Qabc\$xyz\E       abc\$xyz          abc\$xyz
963        \Qabc\E\$\Qxyz\E   abc$xyz           abc$xyz
964    
965    For compatibility with Perl, \Q...\E sequences are recognized inside character
966    classes as well as outside them.
967    
968    9. Re-organized 3 code statements in pcretest to avoid "overflow in
969    floating-point constant arithmetic" warnings from a Microsoft compiler. Added a
970    (size_t) cast to one statement in pcretest and one in pcreposix to avoid
971    signed/unsigned warnings.
972    
973    10. SunOS4 doesn't have strtoul(). This was used only for unpicking the -o
974    option for pcretest, so I've replaced it by a simple function that does just
975    that job.
976    
977    11. pcregrep was ending with code 0 instead of 2 for the commands "pcregrep" or
978    "pcregrep -".
979    
980    12. Added "possessive quantifiers" ?+, *+, ++, and {,}+ which come from Sun's
981    Java package. This provides some syntactic sugar for simple cases of what my
982    documentation calls "once-only subpatterns". A pattern such as x*+ is the same
983    as (?>x*). In other words, if what is inside (?>...) is just a single repeated
984    item, you can use this simplified notation. Note that only makes sense with
985    greedy quantifiers. Consequently, the use of the possessive quantifier forces
986    greediness, whatever the setting of the PCRE_UNGREEDY option.
987    
988    13. A change of greediness default within a pattern was not taking effect at
989    the current level for patterns like /(b+(?U)a+)/. It did apply to parenthesized
990    subpatterns that followed. Patterns like /b+(?U)a+/ worked because the option
991    was abstracted outside.
992    
993    14. PCRE now supports the \G assertion. It is true when the current matching
994    position is at the start point of the match. This differs from \A when the
995    starting offset is non-zero. Used with the /g option of pcretest (or similar
996    code), it works in the same way as it does for Perl's /g option. If all
997    alternatives of a regex begin with \G, the expression is anchored to the start
998    match position, and the "anchored" flag is set in the compiled expression.
999    
1000    15. Some bugs concerning the handling of certain option changes within patterns
1001    have been fixed. These applied to options other than (?ims). For example,
1002    "a(?x: b c )d" did not match "XabcdY" but did match "Xa b c dY". It should have
1003    been the other way round. Some of this was related to change 7 above.
1004    
1005    16. PCRE now gives errors for /[.x.]/ and /[=x=]/ as unsupported POSIX
1006    features, as Perl does. Previously, PCRE gave the warnings only for /[[.x.]]/
1007    and /[[=x=]]/. PCRE now also gives an error for /[:name:]/ because it supports
1008    POSIX classes only within a class (e.g. /[[:alpha:]]/).
1009    
1010    17. Added support for Perl's \C escape. This matches one byte, even in UTF8
1011    mode. Unlike ".", it always matches newline, whatever the setting of
1012    PCRE_DOTALL. However, PCRE does not permit \C to appear in lookbehind
1013    assertions. Perl allows it, but it doesn't (in general) work because it can't
1014    calculate the length of the lookbehind. At least, that's the case for Perl
1015    5.8.0 - I've been told they are going to document that it doesn't work in
1016    future.
1017    
1018    18. Added an error diagnosis for escapes that PCRE does not support: these are
1019    \L, \l, \N, \P, \p, \U, \u, and \X.
1020    
1021    19. Although correctly diagnosing a missing ']' in a character class, PCRE was
1022    reading past the end of the pattern in cases such as /[abcd/.
1023    
1024    20. PCRE was getting more memory than necessary for patterns with classes that
1025    contained both POSIX named classes and other characters, e.g. /[[:space:]abc/.
1026    
1027    21. Added some code, conditional on #ifdef VPCOMPAT, to make life easier for
1028    compiling PCRE for use with Virtual Pascal.
1029    
1030    22. Small fix to the Makefile to make it work properly if the build is done
1031    outside the source tree.
1032    
1033    23. Added a new extension: a condition to go with recursion. If a conditional
1034    subpattern starts with (?(R) the "true" branch is used if recursion has
1035    happened, whereas the "false" branch is used only at the top level.
1036    
1037    24. When there was a very long string of literal characters (over 255 bytes
1038    without UTF support, over 250 bytes with UTF support), the computation of how
1039    much memory was required could be incorrect, leading to segfaults or other
1040    strange effects.
1041    
1042    25. PCRE was incorrectly assuming anchoring (either to start of subject or to
1043    start of line for a non-DOTALL pattern) when a pattern started with (.*) and
1044    there was a subsequent back reference to those brackets. This meant that, for
1045    example, /(.*)\d+\1/ failed to match "abc123bc". Unfortunately, it isn't
1046    possible to check for precisely this case. All we can do is abandon the
1047    optimization if .* occurs inside capturing brackets when there are any back
1048    references whatsoever. (See below for a better fix that came later.)
1049    
1050    26. The handling of the optimization for finding the first character of a
1051    non-anchored pattern, and for finding a character that is required later in the
1052    match were failing in some cases. This didn't break the matching; it just
1053    failed to optimize when it could. The way this is done has been re-implemented.
1054    
1055    27. Fixed typo in error message for invalid (?R item (it said "(?p").
1056    
1057    28. Added a new feature that provides some of the functionality that Perl
1058    provides with (?{...}). The facility is termed a "callout". The way it is done
1059    in PCRE is for the caller to provide an optional function, by setting
1060    pcre_callout to its entry point. Like pcre_malloc and pcre_free, this is a
1061    global variable. By default it is unset, which disables all calling out. To get
1062    the function called, the regex must include (?C) at appropriate points. This
1063    is, in fact, equivalent to (?C0), and any number <= 255 may be given with (?C).
1064    This provides a means of identifying different callout points. When PCRE
1065    reaches such a point in the regex, if pcre_callout has been set, the external
1066    function is called. It is provided with data in a structure called
1067    pcre_callout_block, which is defined in pcre.h. If the function returns 0,
1068    matching continues; if it returns a non-zero value, the match at the current
1069    point fails. However, backtracking will occur if possible. [This was changed
1070    later and other features added - see item 49 below.]
1071    
1072    29. pcretest is upgraded to test the callout functionality. It provides a
1073    callout function that displays information. By default, it shows the start of
1074    the match and the current position in the text. There are some new data escapes
1075    to vary what happens:
1076    
1077        \C+         in addition, show current contents of captured substrings
1078        \C-         do not supply a callout function
1079        \C!n        return 1 when callout number n is reached
1080        \C!n!m      return 1 when callout number n is reached for the mth time
1081    
1082    30. If pcregrep was called with the -l option and just a single file name, it
1083    output "<stdin>" if a match was found, instead of the file name.
1084    
1085    31. Improve the efficiency of the POSIX API to PCRE. If the number of capturing
1086    slots is less than POSIX_MALLOC_THRESHOLD, use a block on the stack to pass to
1087    pcre_exec(). This saves a malloc/free per call. The default value of
1088    POSIX_MALLOC_THRESHOLD is 10; it can be changed by --with-posix-malloc-threshold
1089    when configuring.
1090    
1091    32. The default maximum size of a compiled pattern is 64K. There have been a
1092    few cases of people hitting this limit. The code now uses macros to handle the
1093    storing of links as offsets within the compiled pattern. It defaults to 2-byte
1094    links, but this can be changed to 3 or 4 bytes by --with-link-size when
1095    configuring. Tests 2 and 5 work only with 2-byte links because they output
1096    debugging information about compiled patterns.
1097    
1098    33. Internal code re-arrangements:
1099    
1100    (a) Moved the debugging function for printing out a compiled regex into
1101        its own source file (printint.c) and used #include to pull it into
1102        pcretest.c and, when DEBUG is defined, into pcre.c, instead of having two
1103        separate copies.
1104    
1105    (b) Defined the list of op-code names for debugging as a macro in
1106        internal.h so that it is next to the definition of the opcodes.
1107    
1108    (c) Defined a table of op-code lengths for simpler skipping along compiled
1109        code. This is again a macro in internal.h so that it is next to the
1110        definition of the opcodes.
1111    
1112    34. Added support for recursive calls to individual subpatterns, along the
1113    lines of Robin Houston's patch (but implemented somewhat differently).
1114    
1115    35. Further mods to the Makefile to help Win32. Also, added code to pcregrep to
1116    allow it to read and process whole directories in Win32. This code was
1117    contributed by Lionel Fourquaux; it has not been tested by me.
1118    
1119    36. Added support for named subpatterns. The Python syntax (?P<name>...) is
1120    used to name a group. Names consist of alphanumerics and underscores, and must
1121    be unique. Back references use the syntax (?P=name) and recursive calls use
1122    (?P>name) which is a PCRE extension to the Python extension. Groups still have
1123    numbers. The function pcre_fullinfo() can be used after compilation to extract
1124    a name/number map. There are three relevant calls:
1125    
1126      PCRE_INFO_NAMEENTRYSIZE        yields the size of each entry in the map
1127      PCRE_INFO_NAMECOUNT            yields the number of entries
1128      PCRE_INFO_NAMETABLE            yields a pointer to the map.
1129    
1130    The map is a vector of fixed-size entries. The size of each entry depends on
1131    the length of the longest name used. The first two bytes of each entry are the
1132    group number, most significant byte first. There follows the corresponding
1133    name, zero terminated. The names are in alphabetical order.
1134    
1135    37. Make the maximum literal string in the compiled code 250 for the non-UTF-8
1136    case instead of 255. Making it the same both with and without UTF-8 support
1137    means that the same test output works with both.
1138    
1139    38. There was a case of malloc(0) in the POSIX testing code in pcretest. Avoid
1140    calling malloc() with a zero argument.
1141    
1142    39. Change 25 above had to resort to a heavy-handed test for the .* anchoring
1143    optimization. I've improved things by keeping a bitmap of backreferences with
1144    numbers 1-31 so that if .* occurs inside capturing brackets that are not in
1145    fact referenced, the optimization can be applied. It is unlikely that a
1146    relevant occurrence of .* (i.e. one which might indicate anchoring or forcing
1147    the match to follow \n) will appear inside brackets with a number greater than
1148    31, but if it does, any back reference > 31 suppresses the optimization.
1149    
1150    40. Added a new compile-time option PCRE_NO_AUTO_CAPTURE. This has the effect
1151    of disabling numbered capturing parentheses. Any opening parenthesis that is
1152    not followed by ? behaves as if it were followed by ?: but named parentheses
1153    can still be used for capturing (and they will acquire numbers in the usual
1154    way).
1155    
1156    41. Redesigned the return codes from the match() function into yes/no/error so
1157    that errors can be passed back from deep inside the nested calls. A malloc
1158    failure while inside a recursive subpattern call now causes the
1159    PCRE_ERROR_NOMEMORY return instead of quietly going wrong.
1160    
1161    42. It is now possible to set a limit on the number of times the match()
1162    function is called in a call to pcre_exec(). This facility makes it possible to
1163    limit the amount of recursion and backtracking, though not in a directly
1164    obvious way, because the match() function is used in a number of different
1165    circumstances. The count starts from zero for each position in the subject
1166    string (for non-anchored patterns). The default limit is, for compatibility, a
1167    large number, namely 10 000 000. You can change this in two ways:
1168    
1169    (a) When configuring PCRE before making, you can use --with-match-limit=n
1170        to set a default value for the compiled library.
1171    
1172    (b) For each call to pcre_exec(), you can pass a pcre_extra block in which
1173        a different value is set. See 45 below.
1174    
1175    If the limit is exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT.
1176    
1177    43. Added a new function pcre_config(int, void *) to enable run-time extraction
1178    of things that can be changed at compile time. The first argument specifies
1179    what is wanted and the second points to where the information is to be placed.
1180    The current list of available information is:
1181    
1182      PCRE_CONFIG_UTF8
1183    
1184    The output is an integer that is set to one if UTF-8 support is available;
1185    otherwise it is set to zero.
1186    
1187      PCRE_CONFIG_NEWLINE
1188    
1189    The output is an integer that it set to the value of the code that is used for
1190    newline. It is either LF (10) or CR (13).
1191    
1192      PCRE_CONFIG_LINK_SIZE
1193    
1194    The output is an integer that contains the number of bytes used for internal
1195    linkage in compiled expressions. The value is 2, 3, or 4. See item 32 above.
1196    
1197      PCRE_CONFIG_POSIX_MALLOC_THRESHOLD
1198    
1199    The output is an integer that contains the threshold above which the POSIX
1200    interface uses malloc() for output vectors. See item 31 above.
1201    
1202      PCRE_CONFIG_MATCH_LIMIT
1203    
1204    The output is an unsigned integer that contains the default limit of the number
1205    of match() calls in a pcre_exec() execution. See 42 above.
1206    
1207    44. pcretest has been upgraded by the addition of the -C option. This causes it
1208    to extract all the available output from the new pcre_config() function, and to
1209    output it. The program then exits immediately.
1210    
1211    45. A need has arisen to pass over additional data with calls to pcre_exec() in
1212    order to support additional features. One way would have been to define
1213    pcre_exec2() (for example) with extra arguments, but this would not have been
1214    extensible, and would also have required all calls to the original function to
1215    be mapped to the new one. Instead, I have chosen to extend the mechanism that
1216    is used for passing in "extra" data from pcre_study().
1217    
1218    The pcre_extra structure is now exposed and defined in pcre.h. It currently
1219    contains the following fields:
1220    
1221      flags         a bitmap indicating which of the following fields are set
1222      study_data    opaque data from pcre_study()
1223      match_limit   a way of specifying a limit on match() calls for a specific
1224                      call to pcre_exec()
1225      callout_data  data for callouts (see 49 below)
1226    
1227    The flag bits are also defined in pcre.h, and are
1228    
1229      PCRE_EXTRA_STUDY_DATA
1230      PCRE_EXTRA_MATCH_LIMIT
1231      PCRE_EXTRA_CALLOUT_DATA
1232    
1233    The pcre_study() function now returns one of these new pcre_extra blocks, with
1234    the actual study data pointed to by the study_data field, and the
1235    PCRE_EXTRA_STUDY_DATA flag set. This can be passed directly to pcre_exec() as
1236    before. That is, this change is entirely upwards-compatible and requires no
1237    change to existing code.
1238    
1239    If you want to pass in additional data to pcre_exec(), you can either place it
1240    in a pcre_extra block provided by pcre_study(), or create your own pcre_extra
1241    block.
1242    
1243    46. pcretest has been extended to test the PCRE_EXTRA_MATCH_LIMIT feature. If a
1244    data string contains the escape sequence \M, pcretest calls pcre_exec() several
1245    times with different match limits, until it finds the minimum value needed for
1246    pcre_exec() to complete. The value is then output. This can be instructive; for
1247    most simple matches the number is quite small, but for pathological cases it
1248    gets very large very quickly.
1249    
1250    47. There's a new option for pcre_fullinfo() called PCRE_INFO_STUDYSIZE. It
1251    returns the size of the data block pointed to by the study_data field in a
1252    pcre_extra block, that is, the value that was passed as the argument to
1253    pcre_malloc() when PCRE was getting memory in which to place the information
1254    created by pcre_study(). The fourth argument should point to a size_t variable.
1255    pcretest has been extended so that this information is shown after a successful
1256    pcre_study() call when information about the compiled regex is being displayed.
1257    
1258    48. Cosmetic change to Makefile: there's no need to have / after $(DESTDIR)
1259    because what follows is always an absolute path. (Later: it turns out that this
1260    is more than cosmetic for MinGW, because it doesn't like empty path
1261    components.)
1262    
1263    49. Some changes have been made to the callout feature (see 28 above):
1264    
1265    (i)  A callout function now has three choices for what it returns:
1266    
1267           0  =>  success, carry on matching
1268         > 0  =>  failure at this point, but backtrack if possible
1269         < 0  =>  serious error, return this value from pcre_exec()
1270    
1271         Negative values should normally be chosen from the set of PCRE_ERROR_xxx
1272         values. In particular, returning PCRE_ERROR_NOMATCH forces a standard
1273         "match failed" error. The error number PCRE_ERROR_CALLOUT is reserved for
1274         use by callout functions. It will never be used by PCRE itself.
1275    
1276    (ii) The pcre_extra structure (see 45 above) has a void * field called
1277         callout_data, with corresponding flag bit PCRE_EXTRA_CALLOUT_DATA. The
1278         pcre_callout_block structure has a field of the same name. The contents of
1279         the field passed in the pcre_extra structure are passed to the callout
1280         function in the corresponding field in the callout block. This makes it
1281         easier to use the same callout-containing regex from multiple threads. For
1282         testing, the pcretest program has a new data escape
1283    
1284           \C*n        pass the number n (may be negative) as callout_data
1285    
1286         If the callout function in pcretest receives a non-zero value as
1287         callout_data, it returns that value.
1288    
1289    50. Makefile wasn't handling CFLAGS properly when compiling dftables. Also,
1290    there were some redundant $(CFLAGS) in commands that are now specified as
1291    $(LINK), which already includes $(CFLAGS).
1292    
1293    51. Extensions to UTF-8 support are listed below. These all apply when (a) PCRE
1294    has been compiled with UTF-8 support *and* pcre_compile() has been compiled
1295    with the PCRE_UTF8 flag. Patterns that are compiled without that flag assume
1296    one-byte characters throughout. Note that case-insensitive matching applies
1297    only to characters whose values are less than 256. PCRE doesn't support the
1298    notion of cases for higher-valued characters.
1299    
1300    (i)   A character class whose characters are all within 0-255 is handled as
1301          a bit map, and the map is inverted for negative classes. Previously, a
1302          character > 255 always failed to match such a class; however it should
1303          match if the class was a negative one (e.g. [^ab]). This has been fixed.
1304    
1305    (ii)  A negated character class with a single character < 255 is coded as
1306          "not this character" (OP_NOT). This wasn't working properly when the test
1307          character was multibyte, either singly or repeated.
1308    
1309    (iii) Repeats of multibyte characters are now handled correctly in UTF-8
1310          mode, for example: \x{100}{2,3}.
1311    
1312    (iv)  The character escapes \b, \B, \d, \D, \s, \S, \w, and \W (either
1313          singly or repeated) now correctly test multibyte characters. However,
1314          PCRE doesn't recognize any characters with values greater than 255 as
1315          digits, spaces, or word characters. Such characters always match \D, \S,
1316          and \W, and never match \d, \s, or \w.
1317    
1318    (v)   Classes may now contain characters and character ranges with values
1319          greater than 255. For example: [ab\x{100}-\x{400}].
1320    
1321    (vi)  pcregrep now has a --utf-8 option (synonym -u) which makes it call
1322          PCRE in UTF-8 mode.
1323    
1324    52. The info request value PCRE_INFO_FIRSTCHAR has been renamed
1325    PCRE_INFO_FIRSTBYTE because it is a byte value. However, the old name is
1326    retained for backwards compatibility. (Note that LASTLITERAL is also a byte
1327    value.)
1328    
1329    53. The single man page has become too large. I have therefore split it up into
1330    a number of separate man pages. These also give rise to individual HTML pages;
1331    these are now put in a separate directory, and there is an index.html page that
1332    lists them all. Some hyperlinking between the pages has been installed.
1333    
1334    54. Added convenience functions for handling named capturing parentheses.
1335    
1336    55. Unknown escapes inside character classes (e.g. [\M]) and escapes that
1337    aren't interpreted therein (e.g. [\C]) are literals in Perl. This is now also
1338    true in PCRE, except when the PCRE_EXTENDED option is set, in which case they
1339    are faulted.
1340    
1341    56. Introduced HOST_CC and HOST_CFLAGS which can be set in the environment when
1342    calling configure. These values are used when compiling the dftables.c program
1343    which is run to generate the source of the default character tables. They
1344    default to the values of CC and CFLAGS. If you are cross-compiling PCRE,
1345    you will need to set these values.
1346    
1347    57. Updated the building process for Windows DLL, as provided by Fred Cox.
1348    
1349    
1350    Version 3.9 02-Jan-02
1351    ---------------------
1352    
1353    1. A bit of extraneous text had somehow crept into the pcregrep documentation.
1354    
1355    2. If --disable-static was given, the building process failed when trying to
1356    build pcretest and pcregrep. (For some reason it was using libtool to compile
1357    them, which is not right, as they aren't part of the library.)
1358    
1359    
1360    Version 3.8 18-Dec-01
1361    ---------------------
1362    
1363    1. The experimental UTF-8 code was completely screwed up. It was packing the
1364    bytes in the wrong order. How dumb can you get?
1365    
1366    
1367    Version 3.7 29-Oct-01
1368    ---------------------
1369    
1370    1. In updating pcretest to check change 1 of version 3.6, I screwed up.
1371    This caused pcretest, when used on the test data, to segfault. Unfortunately,
1372    this didn't happen under Solaris 8, where I normally test things.
1373    
1374    2. The Makefile had to be changed to make it work on BSD systems, where 'make'
1375    doesn't seem to recognize that ./xxx and xxx are the same file. (This entry
1376    isn't in ChangeLog distributed with 3.7 because I forgot when I hastily made
1377    this fix an hour or so after the initial 3.7 release.)
1378    
1379    
1380    Version 3.6 23-Oct-01
1381    ---------------------
1382    
1383    1. Crashed with /(sens|respons)e and \1ibility/ and "sense and sensibility" if
1384    offsets passed as NULL with zero offset count.
1385    
1386    2. The config.guess and config.sub files had not been updated when I moved to
1387    the latest autoconf.
1388    
1389    
1390    Version 3.5 15-Aug-01
1391    ---------------------
1392    
1393    1. Added some missing #if !defined NOPOSIX conditionals in pcretest.c that
1394    had been forgotten.
1395    
1396    2. By using declared but undefined structures, we can avoid using "void"
1397    definitions in pcre.h while keeping the internal definitions of the structures
1398    private.
1399    
1400    3. The distribution is now built using autoconf 2.50 and libtool 1.4. From a
1401    user point of view, this means that both static and shared libraries are built
1402    by default, but this can be individually controlled. More of the work of
1403    handling this static/shared cases is now inside libtool instead of PCRE's make
1404    file.
1405    
1406    4. The pcretest utility is now installed along with pcregrep because it is
1407    useful for users (to test regexs) and by doing this, it automatically gets
1408    relinked by libtool. The documentation has been turned into a man page, so
1409    there are now .1, .txt, and .html versions in /doc.
1410    
1411    5. Upgrades to pcregrep:
1412       (i)   Added long-form option names like gnu grep.
1413       (ii)  Added --help to list all options with an explanatory phrase.
1414       (iii) Added -r, --recursive to recurse into sub-directories.
1415       (iv)  Added -f, --file to read patterns from a file.
1416    
1417    6. pcre_exec() was referring to its "code" argument before testing that
1418    argument for NULL (and giving an error if it was NULL).
1419    
1420    7. Upgraded Makefile.in to allow for compiling in a different directory from
1421    the source directory.
1422    
1423    8. Tiny buglet in pcretest: when pcre_fullinfo() was called to retrieve the
1424    options bits, the pointer it was passed was to an int instead of to an unsigned
1425    long int. This mattered only on 64-bit systems.
1426    
1427    9. Fixed typo (3.4/1) in pcre.h again. Sigh. I had changed pcre.h (which is
1428    generated) instead of pcre.in, which it its source. Also made the same change
1429    in several of the .c files.
1430    
1431    10. A new release of gcc defines printf() as a macro, which broke pcretest
1432    because it had an ifdef in the middle of a string argument for printf(). Fixed
1433    by using separate calls to printf().
1434    
1435    11. Added --enable-newline-is-cr and --enable-newline-is-lf to the configure
1436    script, to force use of CR or LF instead of \n in the source. On non-Unix
1437    systems, the value can be set in config.h.
1438    
1439    12. The limit of 200 on non-capturing parentheses is a _nesting_ limit, not an
1440    absolute limit. Changed the text of the error message to make this clear, and
1441    likewise updated the man page.
1442    
1443    13. The limit of 99 on the number of capturing subpatterns has been removed.
1444    The new limit is 65535, which I hope will not be a "real" limit.
1445    
1446    
1447    Version 3.4 22-Aug-00
1448    ---------------------
1449    
1450    1. Fixed typo in pcre.h: unsigned const char * changed to const unsigned char *.
1451    
1452    2. Diagnose condition (?(0) as an error instead of crashing on matching.
1453    
1454    
1455    Version 3.3 01-Aug-00
1456    ---------------------
1457    
1458    1. If an octal character was given, but the value was greater than \377, it
1459    was not getting masked to the least significant bits, as documented. This could
1460    lead to crashes in some systems.
1461    
1462    2. Perl 5.6 (if not earlier versions) accepts classes like [a-\d] and treats
1463    the hyphen as a literal. PCRE used to give an error; it now behaves like Perl.
1464    
1465    3. Added the functions pcre_free_substring() and pcre_free_substring_list().
1466    These just pass their arguments on to (pcre_free)(), but they are provided
1467    because some uses of PCRE bind it to non-C systems that can call its functions,
1468    but cannot call free() or pcre_free() directly.
1469    
1470    4. Add "make test" as a synonym for "make check". Corrected some comments in
1471    the Makefile.
1472    
1473    5. Add $(DESTDIR)/ in front of all the paths in the "install" target in the
1474    Makefile.
1475    
1476    6. Changed the name of pgrep to pcregrep, because Solaris has introduced a
1477    command called pgrep for grepping around the active processes.
1478    
1479    7. Added the beginnings of support for UTF-8 character strings.
1480    
1481    8. Arranged for the Makefile to pass over the settings of CC, CFLAGS, and
1482    RANLIB to ./ltconfig so that they are used by libtool. I think these are all
1483    the relevant ones. (AR is not passed because ./ltconfig does its own figuring
1484    out for the ar command.)
1485    
1486    
1487    Version 3.2 12-May-00
1488    ---------------------
1489    
1490    This is purely a bug fixing release.
1491    
1492    1. If the pattern /((Z)+|A)*/ was matched agained ZABCDEFG it matched Z instead
1493    of ZA. This was just one example of several cases that could provoke this bug,
1494    which was introduced by change 9 of version 2.00. The code for breaking
1495    infinite loops after an iteration that matches an empty string was't working
1496    correctly.
1497    
1498    2. The pcretest program was not imitating Perl correctly for the pattern /a*/g
1499    when matched against abbab (for example). After matching an empty string, it
1500    wasn't forcing anchoring when setting PCRE_NOTEMPTY for the next attempt; this
1501    caused it to match further down the string than it should.
1502    
1503    3. The code contained an inclusion of sys/types.h. It isn't clear why this
1504    was there because it doesn't seem to be needed, and it causes trouble on some
1505    systems, as it is not a Standard C header. It has been removed.
1506    
1507    4. Made 4 silly changes to the source to avoid stupid compiler warnings that
1508    were reported on the Macintosh. The changes were from
1509    
1510      while ((c = *(++ptr)) != 0 && c != '\n');
1511    to
1512      while ((c = *(++ptr)) != 0 && c != '\n') ;
1513    
1514    Totally extraordinary, but if that's what it takes...
1515    
1516    5. PCRE is being used in one environment where neither memmove() nor bcopy() is
1517    available. Added HAVE_BCOPY and an autoconf test for it; if neither
1518    HAVE_MEMMOVE nor HAVE_BCOPY is set, use a built-in emulation function which
1519    assumes the way PCRE uses memmove() (always moving upwards).
1520    
1521    6. PCRE is being used in one environment where strchr() is not available. There
1522    was only one use in pcre.c, and writing it out to avoid strchr() probably gives
1523    faster code anyway.
1524    
1525    
1526    Version 3.1 09-Feb-00
1527    ---------------------
1528    
1529    The only change in this release is the fixing of some bugs in Makefile.in for
1530    the "install" target:
1531    
1532    (1) It was failing to install pcreposix.h.
1533    
1534    (2) It was overwriting the pcre.3 man page with the pcreposix.3 man page.
1535    
1536    
1537    Version 3.0 01-Feb-00
1538    ---------------------
1539    
1540    1. Add support for the /+ modifier to perltest (to output $` like it does in
1541    pcretest).
1542    
1543    2. Add support for the /g modifier to perltest.
1544    
1545    3. Fix pcretest so that it behaves even more like Perl for /g when the pattern
1546    matches null strings.
1547    
1548    4. Fix perltest so that it doesn't do unwanted things when fed an empty
1549    pattern. Perl treats empty patterns specially - it reuses the most recent
1550    pattern, which is not what we want. Replace // by /(?#)/ in order to avoid this
1551    effect.
1552    
1553    5. The POSIX interface was broken in that it was just handing over the POSIX
1554    captured string vector to pcre_exec(), but (since release 2.00) PCRE has
1555    required a bigger vector, with some working space on the end. This means that
1556    the POSIX wrapper now has to get and free some memory, and copy the results.
1557    
1558    6. Added some simple autoconf support, placing the test data and the
1559    documentation in separate directories, re-organizing some of the
1560    information files, and making it build pcre-config (a GNU standard). Also added
1561    libtool support for building PCRE as a shared library, which is now the
1562    default.
1563    
1564    7. Got rid of the leading zero in the definition of PCRE_MINOR because 08 and
1565    09 are not valid octal constants. Single digits will be used for minor values
1566    less than 10.
1567    
1568    8. Defined REG_EXTENDED and REG_NOSUB as zero in the POSIX header, so that
1569    existing programs that set these in the POSIX interface can use PCRE without
1570    modification.
1571    
1572    9. Added a new function, pcre_fullinfo() with an extensible interface. It can
1573    return all that pcre_info() returns, plus additional data. The pcre_info()
1574    function is retained for compatibility, but is considered to be obsolete.
1575    
1576    10. Added experimental recursion feature (?R) to handle one common case that
1577    Perl 5.6 will be able to do with (?p{...}).
1578    
1579    11. Added support for POSIX character classes like [:alpha:], which Perl is
1580    adopting.
1581    
1582    
1583    Version 2.08 31-Aug-99
1584    ----------------------
1585    
1586    1. When startoffset was not zero and the pattern began with ".*", PCRE was not
1587    trying to match at the startoffset position, but instead was moving forward to
1588    the next newline as if a previous match had failed.
1589    
1590    2. pcretest was not making use of PCRE_NOTEMPTY when repeating for /g and /G,
1591    and could get into a loop if a null string was matched other than at the start
1592    of the subject.
1593    
1594    3. Added definitions of PCRE_MAJOR and PCRE_MINOR to pcre.h so the version can
1595    be distinguished at compile time, and for completeness also added PCRE_DATE.
1596    
1597    5. Added Paul Sokolovsky's minor changes to make it easy to compile a Win32 DLL
1598    in GnuWin32 environments.
1599    
1600    
1601    Version 2.07 29-Jul-99
1602    ----------------------
1603    
1604    1. The documentation is now supplied in plain text form and HTML as well as in
1605    the form of man page sources.
1606    
1607    2. C++ compilers don't like assigning (void *) values to other pointer types.
1608    In particular this affects malloc(). Although there is no problem in Standard
1609    C, I've put in casts to keep C++ compilers happy.
1610    
1611    3. Typo on pcretest.c; a cast of (unsigned char *) in the POSIX regexec() call
1612    should be (const char *).
1613    
1614    4. If NOPOSIX is defined, pcretest.c compiles without POSIX support. This may
1615    be useful for non-Unix systems who don't want to bother with the POSIX stuff.
1616    However, I haven't made this a standard facility. The documentation doesn't
1617    mention it, and the Makefile doesn't support it.
1618    
1619    5. The Makefile now contains an "install" target, with editable destinations at
1620    the top of the file. The pcretest program is not installed.
1621    
1622    6. pgrep -V now gives the PCRE version number and date.
1623    
1624    7. Fixed bug: a zero repetition after a literal string (e.g. /abcde{0}/) was
1625    causing the entire string to be ignored, instead of just the last character.
1626    
1627    8. If a pattern like /"([^\\"]+|\\.)*"/ is applied in the normal way to a
1628    non-matching string, it can take a very, very long time, even for strings of
1629    quite modest length, because of the nested recursion. PCRE now does better in
1630    some of these cases. It does this by remembering the last required literal
1631    character in the pattern, and pre-searching the subject to ensure it is present
1632    before running the real match. In other words, it applies a heuristic to detect
1633    some types of certain failure quickly, and in the above example, if presented
1634    with a string that has no trailing " it gives "no match" very quickly.
1635    
1636    9. A new runtime option PCRE_NOTEMPTY causes null string matches to be ignored;
1637    other alternatives are tried instead.
1638    
1639    
1640    Version 2.06 09-Jun-99
1641    ----------------------
1642    
1643    1. Change pcretest's output for amount of store used to show just the code
1644    space, because the remainder (the data block) varies in size between 32-bit and
1645    64-bit systems.
1646    
1647    2. Added an extra argument to pcre_exec() to supply an offset in the subject to
1648    start matching at. This allows lookbehinds to work when searching for multiple
1649    occurrences in a string.
1650    
1651    3. Added additional options to pcretest for testing multiple occurrences:
1652    
1653       /+   outputs the rest of the string that follows a match
1654       /g   loops for multiple occurrences, using the new startoffset argument
1655       /G   loops for multiple occurrences by passing an incremented pointer
1656    
1657    4. PCRE wasn't doing the "first character" optimization for patterns starting
1658    with \b or \B, though it was doing it for other lookbehind assertions. That is,
1659    it wasn't noticing that a match for a pattern such as /\bxyz/ has to start with
1660    the letter 'x'. On long subject strings, this gives a significant speed-up.
1661    
1662    
1663    Version 2.05 21-Apr-99
1664    ----------------------
1665    
1666    1. Changed the type of magic_number from int to long int so that it works
1667    properly on 16-bit systems.
1668    
1669    2. Fixed a bug which caused patterns starting with .* not to work correctly
1670    when the subject string contained newline characters. PCRE was assuming
1671    anchoring for such patterns in all cases, which is not correct because .* will
1672    not pass a newline unless PCRE_DOTALL is set. It now assumes anchoring only if
1673    DOTALL is set at top level; otherwise it knows that patterns starting with .*
1674    must be retried after every newline in the subject.
1675    
1676    
1677    Version 2.04 18-Feb-99
1678    ----------------------
1679    
1680    1. For parenthesized subpatterns with repeats whose minimum was zero, the
1681    computation of the store needed to hold the pattern was incorrect (too large).
1682    If such patterns were nested a few deep, this could multiply and become a real
1683    problem.
1684    
1685    2. Added /M option to pcretest to show the memory requirement of a specific
1686    pattern. Made -m a synonym of -s (which does this globally) for compatibility.
1687    
1688    3. Subpatterns of the form (regex){n,m} (i.e. limited maximum) were being
1689    compiled in such a way that the backtracking after subsequent failure was
1690    pessimal. Something like (a){0,3} was compiled as (a)?(a)?(a)? instead of
1691    ((a)((a)(a)?)?)? with disastrous performance if the maximum was of any size.
1692    
1693    
1694    Version 2.03 02-Feb-99
1695    ----------------------
1696    
1697    1. Fixed typo and small mistake in man page.
1698    
1699    2. Added 4th condition (GPL supersedes if conflict) and created separate
1700    LICENCE file containing the conditions.
1701    
1702    3. Updated pcretest so that patterns such as /abc\/def/ work like they do in
1703    Perl, that is the internal \ allows the delimiter to be included in the
1704    pattern. Locked out the use of \ as a delimiter. If \ immediately follows
1705    the final delimiter, add \ to the end of the pattern (to test the error).
1706    
1707    4. Added the convenience functions for extracting substrings after a successful
1708    match. Updated pcretest to make it able to test these functions.
1709    
1710    
1711    Version 2.02 14-Jan-99
1712    ----------------------
1713    
1714    1. Initialized the working variables associated with each extraction so that
1715    their saving and restoring doesn't refer to uninitialized store.
1716    
1717    2. Put dummy code into study.c in order to trick the optimizer of the IBM C
1718    compiler for OS/2 into generating correct code. Apparently IBM isn't going to
1719    fix the problem.
1720    
1721    3. Pcretest: the timing code wasn't using LOOPREPEAT for timing execution
1722    calls, and wasn't printing the correct value for compiling calls. Increased the
1723    default value of LOOPREPEAT, and the number of significant figures in the
1724    times.
1725    
1726    4. Changed "/bin/rm" in the Makefile to "-rm" so it works on Windows NT.
1727    
1728    5. Renamed "deftables" as "dftables" to get it down to 8 characters, to avoid
1729    a building problem on Windows NT with a FAT file system.
1730    
1731    
1732    Version 2.01 21-Oct-98
1733    ----------------------
1734    
1735    1. Changed the API for pcre_compile() to allow for the provision of a pointer
1736    to character tables built by pcre_maketables() in the current locale. If NULL
1737    is passed, the default tables are used.
1738    
1739    
1740    Version 2.00 24-Sep-98
1741    ----------------------
1742    
1743    1. Since the (>?) facility is in Perl 5.005, don't require PCRE_EXTRA to enable
1744    it any more.
1745    
1746    2. Allow quantification of (?>) groups, and make it work correctly.
1747    
1748    3. The first character computation wasn't working for (?>) groups.
1749    
1750    4. Correct the implementation of \Z (it is permitted to match on the \n at the
1751    end of the subject) and add 5.005's \z, which really does match only at the
1752    very end of the subject.
1753    
1754    5. Remove the \X "cut" facility; Perl doesn't have it, and (?> is neater.
1755    
1756    6. Remove the ability to specify CASELESS, MULTILINE, DOTALL, and
1757    DOLLAR_END_ONLY at runtime, to make it possible to implement the Perl 5.005
1758    localized options. All options to pcre_study() were also removed.
1759    
1760    7. Add other new features from 5.005:
1761    
1762       $(?<=           positive lookbehind
1763       $(?<!           negative lookbehind
1764       (?imsx-imsx)    added the unsetting capability
1765                       such a setting is global if at outer level; local otherwise
1766       (?imsx-imsx:)   non-capturing groups with option setting
1767       (?(cond)re|re)  conditional pattern matching
1768    
1769       A backreference to itself in a repeated group matches the previous
1770       captured string.
1771    
1772    8. General tidying up of studying (both automatic and via "study")
1773    consequential on the addition of new assertions.
1774    
1775    9. As in 5.005, unlimited repeated groups that could match an empty substring
1776    are no longer faulted at compile time. Instead, the loop is forcibly broken at
1777    runtime if any iteration does actually match an empty substring.
1778    
1779    10. Include the RunTest script in the distribution.
1780    
1781    11. Added tests from the Perl 5.005_02 distribution. This showed up a few
1782    discrepancies, some of which were old and were also with respect to 5.004. They
1783    have now been fixed.
1784    
1785    
1786    Version 1.09 28-Apr-98
1787    ----------------------
1788    
1789    1. A negated single character class followed by a quantifier with a minimum
1790    value of one (e.g.  [^x]{1,6}  ) was not compiled correctly. This could lead to
1791    program crashes, or just wrong answers. This did not apply to negated classes
1792    containing more than one character, or to minima other than one.
1793    
1794    
1795    Version 1.08 27-Mar-98
1796    ----------------------
1797    
1798    1. Add PCRE_UNGREEDY to invert the greediness of quantifiers.
1799    
1800    2. Add (?U) and (?X) to set PCRE_UNGREEDY and PCRE_EXTRA respectively. The
1801    latter must appear before anything that relies on it in the pattern.
1802    
1803    
1804    Version 1.07 16-Feb-98
1805    ----------------------
1806    
1807    1. A pattern such as /((a)*)*/ was not being diagnosed as in error (unlimited
1808    repeat of a potentially empty string).
1809    
1810    
1811  Version 1.06 23-Jan-98  Version 1.06 23-Jan-98
1812  ----------------------  ----------------------

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