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revision 61 by nigel, Sat Feb 24 21:39:58 2007 UTC revision 361 by ph10, Thu Jul 10 16:03:28 2008 UTC
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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
4  Version 3.0 02-Jan-02  Version 8.0 02 Jul-08
5    ---------------------
7    1.  Replaced UCP searching code with optimized version as implemented for Ad
8        Muncher (http://www.admuncher.com/) by Peter Kankowski. This uses a two-
9        stage table and inline lookup instead of a function, giving speed ups of 2
10        to 5 times on some simple patterns that I tested. Permission was given to
11        distribute the MultiStage2.py script that generates the tables (it's not in
12        the tarball, but is in the Subversion repository).
14    2.  Updated the Unicode datatables to Unicode 5.1.0. This adds yet more
15        scripts.
17    3.  Change 12 for 7.7 introduced a bug in pcre_study() when a pattern contained
18        a group with a zero qualifier. The result of the study could be incorrect,
19        or the function might crash, depending on the pattern.
21    4.  Caseless matching was not working for non-ASCII characters in back
22        references. For example, /(\x{de})\1/8i was not matching \x{de}\x{fe}.
23        It now works when Unicode Property Support is available.
25    5.  In pcretest, an escape such as \x{de} in the data was always generating
26        a UTF-8 string, even in non-UTF-8 mode. Now it generates a single byte in
27        non-UTF-8 mode. If the value is greater than 255, it gives a warning about
28        truncation.
30    6.  Minor bugfix in pcrecpp.cc (change "" == ... to NULL == ...).
32    7.  Added two (int) casts to pcregrep when printing the difference of two
33        pointers, in case they are 64-bit values.
35    8.  Added comments about Mac OS X stack usage to the pcrestack man page and to
36        test 2 if it fails.
38    9.  Added PCRE_CALL_CONVENTION just before the names of all exported functions,
39        and a #define of that name to empty if it is not externally set. This is to
40        allow users of MSVC to set it if necessary.
42    10. The PCRE_EXP_DEFN macro which precedes exported functions was missing from
43        the convenience functions in the pcre_get.c source file.
45    11. An option change at the start of a pattern that had top-level alternatives
46        could cause overwriting and/or a crash. This command provoked a crash in
47        some environments:
49          printf "/(?i)[\xc3\xa9\xc3\xbd]|[\xc3\xa9\xc3\xbdA]/8\n" | pcretest
51        This potential security problem was recorded as CVE-2008-2371.
53    12. For a pattern where the match had to start at the beginning or immediately
54        after a newline (e.g /.*anything/ without the DOTALL flag), pcre_exec() and
55        pcre_dfa_exec() could read past the end of the passed subject if there was
56        no match. To help with detecting such bugs (e.g. with valgrind), I modified
57        pcretest so that it places the subject at the end of its malloc-ed buffer.
60    Version 7.7 07-May-08
61    ---------------------
63    1.  Applied Craig's patch to sort out a long long problem: "If we can't convert
64        a string to a long long, pretend we don't even have a long long." This is
65        done by checking for the strtoq, strtoll, and _strtoi64 functions.
67    2.  Applied Craig's patch to pcrecpp.cc to restore ABI compatibility with
68        pre-7.6 versions, which defined a global no_arg variable instead of putting
69        it in the RE class. (See also #8 below.)
71    3.  Remove a line of dead code, identified by coverity and reported by Nuno
72        Lopes.
74    4.  Fixed two related pcregrep bugs involving -r with --include or --exclude:
76        (1) The include/exclude patterns were being applied to the whole pathnames
77            of files, instead of just to the final components.
79        (2) If there was more than one level of directory, the subdirectories were
80            skipped unless they satisfied the include/exclude conditions. This is
81            inconsistent with GNU grep (and could even be seen as contrary to the
82            pcregrep specification - which I improved to make it absolutely clear).
83            The action now is always to scan all levels of directory, and just
84            apply the include/exclude patterns to regular files.
86    5.  Added the --include_dir and --exclude_dir patterns to pcregrep, and used
87        --exclude_dir in the tests to avoid scanning .svn directories.
89    6.  Applied Craig's patch to the QuoteMeta function so that it escapes the
90        NUL character as backslash + 0 rather than backslash + NUL, because PCRE
91        doesn't support NULs in patterns.
93    7.  Added some missing "const"s to declarations of static tables in
94        pcre_compile.c and pcre_dfa_exec.c.
96    8.  Applied Craig's patch to pcrecpp.cc to fix a problem in OS X that was
97        caused by fix #2  above. (Subsequently also a second patch to fix the
98        first patch. And a third patch - this was a messy problem.)
100    9.  Applied Craig's patch to remove the use of push_back().
102    10. Applied Alan Lehotsky's patch to add REG_STARTEND support to the POSIX
103        matching function regexec().
105    11. Added support for the Oniguruma syntax \g<name>, \g<n>, \g'name', \g'n',
106        which, however, unlike Perl's \g{...}, are subroutine calls, not back
107        references. PCRE supports relative numbers with this syntax (I don't think
108        Oniguruma does).
110    12. Previously, a group with a zero repeat such as (...){0} was completely
111        omitted from the compiled regex. However, this means that if the group
112        was called as a subroutine from elsewhere in the pattern, things went wrong
113        (an internal error was given). Such groups are now left in the compiled
114        pattern, with a new opcode that causes them to be skipped at execution
115        time.
117    13. Added the PCRE_JAVASCRIPT_COMPAT option. This makes the following changes
118        to the way PCRE behaves:
120        (a) A lone ] character is dis-allowed (Perl treats it as data).
122        (b) A back reference to an unmatched subpattern matches an empty string
123            (Perl fails the current match path).
125        (c) A data ] in a character class must be notated as \] because if the
126            first data character in a class is ], it defines an empty class. (In
127            Perl it is not possible to have an empty class.) The empty class []
128            never matches; it forces failure and is equivalent to (*FAIL) or (?!).
129            The negative empty class [^] matches any one character, independently
130            of the DOTALL setting.
132    14. A pattern such as /(?2)[]a()b](abc)/ which had a forward reference to a
133        non-existent subpattern following a character class starting with ']' and
134        containing () gave an internal compiling error instead of "reference to
135        non-existent subpattern". Fortunately, when the pattern did exist, the
136        compiled code was correct. (When scanning forwards to check for the
137        existencd of the subpattern, it was treating the data ']' as terminating
138        the class, so got the count wrong. When actually compiling, the reference
139        was subsequently set up correctly.)
141    15. The "always fail" assertion (?!) is optimzed to (*FAIL) by pcre_compile;
142        it was being rejected as not supported by pcre_dfa_exec(), even though
143        other assertions are supported. I have made pcre_dfa_exec() support
144        (*FAIL).
146    16. The implementation of 13c above involved the invention of a new opcode,
147        OP_ALLANY, which is like OP_ANY but doesn't check the /s flag. Since /s
148        cannot be changed at match time, I realized I could make a small
149        improvement to matching performance by compiling OP_ALLANY instead of
150        OP_ANY for "." when DOTALL was set, and then removing the runtime tests
151        on the OP_ANY path.
153    17. Compiling pcretest on Windows with readline support failed without the
154        following two fixes: (1) Make the unistd.h include conditional on
155        HAVE_UNISTD_H; (2) #define isatty and fileno as _isatty and _fileno.
157    18. Changed CMakeLists.txt and cmake/FindReadline.cmake to arrange for the
158        ncurses library to be included for pcretest when ReadLine support is
159        requested, but also to allow for it to be overridden. This patch came from
160        Daniel Bergström.
162    19. There was a typo in the file ucpinternal.h where f0_rangeflag was defined
163        as 0x00f00000 instead of 0x00800000. Luckily, this would not have caused
164        any errors with the current Unicode tables. Thanks to Peter Kankowski for
165        spotting this.
168    Version 7.6 28-Jan-08
169    ---------------------
171    1.  A character class containing a very large number of characters with
172        codepoints greater than 255 (in UTF-8 mode, of course) caused a buffer
173        overflow.
175    2.  Patch to cut out the "long long" test in pcrecpp_unittest when
176        HAVE_LONG_LONG is not defined.
178    3.  Applied Christian Ehrlicher's patch to update the CMake build files to
179        bring them up to date and include new features. This patch includes:
181        - Fixed PH's badly added libz and libbz2 support.
182        - Fixed a problem with static linking.
183        - Added pcredemo. [But later removed - see 7 below.]
184        - Fixed dftables problem and added an option.
185        - Added a number of HAVE_XXX tests, including HAVE_WINDOWS_H and
186            HAVE_LONG_LONG.
187        - Added readline support for pcretest.
188        - Added an listing of the option settings after cmake has run.
190    4.  A user submitted a patch to Makefile that makes it easy to create
191        "pcre.dll" under mingw when using Configure/Make. I added stuff to
192        Makefile.am that cause it to include this special target, without
193        affecting anything else. Note that the same mingw target plus all
194        the other distribution libraries and programs are now supported
195        when configuring with CMake (see 6 below) instead of with
196        Configure/Make.
198    5.  Applied Craig's patch that moves no_arg into the RE class in the C++ code.
199        This is an attempt to solve the reported problem "pcrecpp::no_arg is not
200        exported in the Windows port". It has not yet been confirmed that the patch
201        solves the problem, but it does no harm.
203    6.  Applied Sheri's patch to CMakeLists.txt to add NON_STANDARD_LIB_PREFIX and
204        NON_STANDARD_LIB_SUFFIX for dll names built with mingw when configured
205        with CMake, and also correct the comment about stack recursion.
207    7.  Remove the automatic building of pcredemo from the ./configure system and
208        from CMakeLists.txt. The whole idea of pcredemo.c is that it is an example
209        of a program that users should build themselves after PCRE is installed, so
210        building it automatically is not really right. What is more, it gave
211        trouble in some build environments.
213    8.  Further tidies to CMakeLists.txt from Sheri and Christian.
216    Version 7.5 10-Jan-08
217    ---------------------
219    1.  Applied a patch from Craig: "This patch makes it possible to 'ignore'
220        values in parens when parsing an RE using the C++ wrapper."
222    2.  Negative specials like \S did not work in character classes in UTF-8 mode.
223        Characters greater than 255 were excluded from the class instead of being
224        included.
226    3.  The same bug as (2) above applied to negated POSIX classes such as
227        [:^space:].
229    4.  PCRECPP_STATIC was referenced in pcrecpp_internal.h, but nowhere was it
230        defined or documented. It seems to have been a typo for PCRE_STATIC, so
231        I have changed it.
233    5.  The construct (?&) was not diagnosed as a syntax error (it referenced the
234        first named subpattern) and a construct such as (?&a) would reference the
235        first named subpattern whose name started with "a" (in other words, the
236        length check was missing). Both these problems are fixed. "Subpattern name
237        expected" is now given for (?&) (a zero-length name), and this patch also
238        makes it give the same error for \k'' (previously it complained that that
239        was a reference to a non-existent subpattern).
241    6.  The erroneous patterns (?+-a) and (?-+a) give different error messages;
242        this is right because (?- can be followed by option settings as well as by
243        digits. I have, however, made the messages clearer.
245    7.  Patterns such as (?(1)a|b) (a pattern that contains fewer subpatterns
246        than the number used in the conditional) now cause a compile-time error.
247        This is actually not compatible with Perl, which accepts such patterns, but
248        treats the conditional as always being FALSE (as PCRE used to), but it
249        seems to me that giving a diagnostic is better.
251    8.  Change "alphameric" to the more common word "alphanumeric" in comments
252        and messages.
254    9.  Fix two occurrences of "backslash" in comments that should have been
255        "backspace".
257    10. Remove two redundant lines of code that can never be obeyed (their function
258        was moved elsewhere).
260    11. The program that makes PCRE's Unicode character property table had a bug
261        which caused it to generate incorrect table entries for sequences of
262        characters that have the same character type, but are in different scripts.
263        It amalgamated them into a single range, with the script of the first of
264        them. In other words, some characters were in the wrong script. There were
265        thirteen such cases, affecting characters in the following ranges:
267          U+002b0 - U+002c1
268          U+0060c - U+0060d
269          U+0061e - U+00612
270          U+0064b - U+0065e
271          U+0074d - U+0076d
272          U+01800 - U+01805
273          U+01d00 - U+01d77
274          U+01d9b - U+01dbf
275          U+0200b - U+0200f
276          U+030fc - U+030fe
277          U+03260 - U+0327f
278          U+0fb46 - U+0fbb1
279          U+10450 - U+1049d
281    12. The -o option (show only the matching part of a line) for pcregrep was not
282        compatible with GNU grep in that, if there was more than one match in a
283        line, it showed only the first of them. It now behaves in the same way as
284        GNU grep.
286    13. If the -o and -v options were combined for pcregrep, it printed a blank
287        line for every non-matching line. GNU grep prints nothing, and pcregrep now
288        does the same. The return code can be used to tell if there were any
289        non-matching lines.
291    14. Added --file-offsets and --line-offsets to pcregrep.
293    15. The pattern (?=something)(?R) was not being diagnosed as a potentially
294        infinitely looping recursion. The bug was that positive lookaheads were not
295        being skipped when checking for a possible empty match (negative lookaheads
296        and both kinds of lookbehind were skipped).
298    16. Fixed two typos in the Windows-only code in pcregrep.c, and moved the
299        inclusion of <windows.h> to before rather than after the definition of
300        INVALID_FILE_ATTRIBUTES (patch from David Byron).
302    17. Specifying a possessive quantifier with a specific limit for a Unicode
303        character property caused pcre_compile() to compile bad code, which led at
304        runtime to PCRE_ERROR_INTERNAL (-14). Examples of patterns that caused this
305        are: /\p{Zl}{2,3}+/8 and /\p{Cc}{2}+/8. It was the possessive "+" that
306        caused the error; without that there was no problem.
308    18. Added --enable-pcregrep-libz and --enable-pcregrep-libbz2.
310    19. Added --enable-pcretest-libreadline.
312    20. In pcrecpp.cc, the variable 'count' was incremented twice in
313        RE::GlobalReplace(). As a result, the number of replacements returned was
314        double what it should be. I removed one of the increments, but Craig sent a
315        later patch that removed the other one (the right fix) and added unit tests
316        that check the return values (which was not done before).
318    21. Several CMake things:
320        (1) Arranged that, when cmake is used on Unix, the libraries end up with
321            the names libpcre and libpcreposix, not just pcre and pcreposix.
323        (2) The above change means that pcretest and pcregrep are now correctly
324            linked with the newly-built libraries, not previously installed ones.
328    22. In UTF-8 mode, with newline set to "any", a pattern such as .*a.*=.b.*
329        crashed when matching a string such as a\x{2029}b (note that \x{2029} is a
330        UTF-8 newline character). The key issue is that the pattern starts .*;
331        this means that the match must be either at the beginning, or after a
332        newline. The bug was in the code for advancing after a failed match and
333        checking that the new position followed a newline. It was not taking
334        account of UTF-8 characters correctly.
336    23. PCRE was behaving differently from Perl in the way it recognized POSIX
337        character classes. PCRE was not treating the sequence [:...:] as a
338        character class unless the ... were all letters. Perl, however, seems to
339        allow any characters between [: and :], though of course it rejects as
340        unknown any "names" that contain non-letters, because all the known class
341        names consist only of letters. Thus, Perl gives an error for [[:1234:]],
342        for example, whereas PCRE did not - it did not recognize a POSIX character
343        class. This seemed a bit dangerous, so the code has been changed to be
344        closer to Perl. The behaviour is not identical to Perl, because PCRE will
345        diagnose an unknown class for, for example, [[:l\ower:]] where Perl will
346        treat it as [[:lower:]]. However, PCRE does now give "unknown" errors where
347        Perl does, and where it didn't before.
349    24. Rewrite so as to remove the single use of %n from pcregrep because in some
350        Windows environments %n is disabled by default.
353    Version 7.4 21-Sep-07
354    ---------------------
356    1.  Change 7.3/28 was implemented for classes by looking at the bitmap. This
357        means that a class such as [\s] counted as "explicit reference to CR or
358        LF". That isn't really right - the whole point of the change was to try to
359        help when there was an actual mention of one of the two characters. So now
360        the change happens only if \r or \n (or a literal CR or LF) character is
361        encountered.
363    2.  The 32-bit options word was also used for 6 internal flags, but the numbers
364        of both had grown to the point where there were only 3 bits left.
365        Fortunately, there was spare space in the data structure, and so I have
366        moved the internal flags into a new 16-bit field to free up more option
367        bits.
369    3.  The appearance of (?J) at the start of a pattern set the DUPNAMES option,
370        but did not set the internal JCHANGED flag - either of these is enough to
371        control the way the "get" function works - but the PCRE_INFO_JCHANGED
372        facility is supposed to tell if (?J) was ever used, so now (?J) at the
373        start sets both bits.
375    4.  Added options (at build time, compile time, exec time) to change \R from
376        matching any Unicode line ending sequence to just matching CR, LF, or CRLF.
378    5.  doc/pcresyntax.html was missing from the distribution.
380    6.  Put back the definition of PCRE_ERROR_NULLWSLIMIT, for backward
381        compatibility, even though it is no longer used.
383    7.  Added macro for snprintf to pcrecpp_unittest.cc and also for strtoll and
384        strtoull to pcrecpp.cc to select the available functions in WIN32 when the
385        windows.h file is present (where different names are used). [This was
386        reversed later after testing - see 16 below.]
388    8.  Changed all #include <config.h> to #include "config.h". There were also
389        some further <pcre.h> cases that I changed to "pcre.h".
391    9.  When pcregrep was used with the --colour option, it missed the line ending
392        sequence off the lines that it output.
394    10. It was pointed out to me that arrays of string pointers cause lots of
395        relocations when a shared library is dynamically loaded. A technique of
396        using a single long string with a table of offsets can drastically reduce
397        these. I have refactored PCRE in four places to do this. The result is
398        dramatic:
400          Originally:                          290
401          After changing UCP table:            187
402          After changing error message table:   43
403          After changing table of "verbs"       36
404          After changing table of Posix names   22
406        Thanks to the folks working on Gregex for glib for this insight.
408    11. --disable-stack-for-recursion caused compiling to fail unless -enable-
409        unicode-properties was also set.
411    12. Updated the tests so that they work when \R is defaulted to ANYCRLF.
413    13. Added checks for ANY and ANYCRLF to pcrecpp.cc where it previously
414        checked only for CRLF.
416    14. Added casts to pcretest.c to avoid compiler warnings.
418    15. Added Craig's patch to various pcrecpp modules to avoid compiler warnings.
420    16. Added Craig's patch to remove the WINDOWS_H tests, that were not working,
421        and instead check for _strtoi64 explicitly, and avoid the use of snprintf()
422        entirely. This removes changes made in 7 above.
424    17. The CMake files have been updated, and there is now more information about
425        building with CMake in the NON-UNIX-USE document.
428    Version 7.3 28-Aug-07
429    ---------------------
431     1. In the rejigging of the build system that eventually resulted in 7.1, the
432        line "#include <pcre.h>" was included in pcre_internal.h. The use of angle
433        brackets there is not right, since it causes compilers to look for an
434        installed pcre.h, not the version that is in the source that is being
435        compiled (which of course may be different). I have changed it back to:
437          #include "pcre.h"
439        I have a vague recollection that the change was concerned with compiling in
440        different directories, but in the new build system, that is taken care of
441        by the VPATH setting the Makefile.
443     2. The pattern .*$ when run in not-DOTALL UTF-8 mode with newline=any failed
444        when the subject happened to end in the byte 0x85 (e.g. if the last
445        character was \x{1ec5}). *Character* 0x85 is one of the "any" newline
446        characters but of course it shouldn't be taken as a newline when it is part
447        of another character. The bug was that, for an unlimited repeat of . in
448        not-DOTALL UTF-8 mode, PCRE was advancing by bytes rather than by
449        characters when looking for a newline.
451     3. A small performance improvement in the DOTALL UTF-8 mode .* case.
453     4. Debugging: adjusted the names of opcodes for different kinds of parentheses
454        in debug output.
456     5. Arrange to use "%I64d" instead of "%lld" and "%I64u" instead of "%llu" for
457        long printing in the pcrecpp unittest when running under MinGW.
459     6. ESC_K was left out of the EBCDIC table.
461     7. Change 7.0/38 introduced a new limit on the number of nested non-capturing
462        parentheses; I made it 1000, which seemed large enough. Unfortunately, the
463        limit also applies to "virtual nesting" when a pattern is recursive, and in
464        this case 1000 isn't so big. I have been able to remove this limit at the
465        expense of backing off one optimization in certain circumstances. Normally,
466        when pcre_exec() would call its internal match() function recursively and
467        immediately return the result unconditionally, it uses a "tail recursion"
468        feature to save stack. However, when a subpattern that can match an empty
469        string has an unlimited repetition quantifier, it no longer makes this
470        optimization. That gives it a stack frame in which to save the data for
471        checking that an empty string has been matched. Previously this was taken
472        from the 1000-entry workspace that had been reserved. So now there is no
473        explicit limit, but more stack is used.
475     8. Applied Daniel's patches to solve problems with the import/export magic
476        syntax that is required for Windows, and which was going wrong for the
477        pcreposix and pcrecpp parts of the library. These were overlooked when this
478        problem was solved for the main library.
480     9. There were some crude static tests to avoid integer overflow when computing
481        the size of patterns that contain repeated groups with explicit upper
482        limits. As the maximum quantifier is 65535, the maximum group length was
483        set at 30,000 so that the product of these two numbers did not overflow a
484        32-bit integer. However, it turns out that people want to use groups that
485        are longer than 30,000 bytes (though not repeat them that many times).
486        Change 7.0/17 (the refactoring of the way the pattern size is computed) has
487        made it possible to implement the integer overflow checks in a much more
488        dynamic way, which I have now done. The artificial limitation on group
489        length has been removed - we now have only the limit on the total length of
490        the compiled pattern, which depends on the LINK_SIZE setting.
492    10. Fixed a bug in the documentation for get/copy named substring when
493        duplicate names are permitted. If none of the named substrings are set, the
494        functions return PCRE_ERROR_NOSUBSTRING (7); the doc said they returned an
495        empty string.
497    11. Because Perl interprets \Q...\E at a high level, and ignores orphan \E
498        instances, patterns such as [\Q\E] or [\E] or even [^\E] cause an error,
499        because the ] is interpreted as the first data character and the
500        terminating ] is not found. PCRE has been made compatible with Perl in this
501        regard. Previously, it interpreted [\Q\E] as an empty class, and [\E] could
502        cause memory overwriting.
504    10. Like Perl, PCRE automatically breaks an unlimited repeat after an empty
505        string has been matched (to stop an infinite loop). It was not recognizing
506        a conditional subpattern that could match an empty string if that
507        subpattern was within another subpattern. For example, it looped when
508        trying to match  (((?(1)X|))*)  but it was OK with  ((?(1)X|)*)  where the
509        condition was not nested. This bug has been fixed.
511    12. A pattern like \X?\d or \P{L}?\d in non-UTF-8 mode could cause a backtrack
512        past the start of the subject in the presence of bytes with the top bit
513        set, for example "\x8aBCD".
515    13. Added Perl 5.10 experimental backtracking controls (*FAIL), (*F), (*PRUNE),
516        (*SKIP), (*THEN), (*COMMIT), and (*ACCEPT).
518    14. Optimized (?!) to (*FAIL).
520    15. Updated the test for a valid UTF-8 string to conform to the later RFC 3629.
521        This restricts code points to be within the range 0 to 0x10FFFF, excluding
522        the "low surrogate" sequence 0xD800 to 0xDFFF. Previously, PCRE allowed the
523        full range 0 to 0x7FFFFFFF, as defined by RFC 2279. Internally, it still
524        does: it's just the validity check that is more restrictive.
526    16. Inserted checks for integer overflows during escape sequence (backslash)
527        processing, and also fixed erroneous offset values for syntax errors during
528        backslash processing.
530    17. Fixed another case of looking too far back in non-UTF-8 mode (cf 12 above)
531        for patterns like [\PPP\x8a]{1,}\x80 with the subject "A\x80".
533    18. An unterminated class in a pattern like (?1)\c[ with a "forward reference"
534        caused an overrun.
536    19. A pattern like (?:[\PPa*]*){8,} which had an "extended class" (one with
537        something other than just ASCII characters) inside a group that had an
538        unlimited repeat caused a loop at compile time (while checking to see
539        whether the group could match an empty string).
541    20. Debugging a pattern containing \p or \P could cause a crash. For example,
542        [\P{Any}] did so. (Error in the code for printing property names.)
544    21. An orphan \E inside a character class could cause a crash.
546    22. A repeated capturing bracket such as (A)? could cause a wild memory
547        reference during compilation.
549    23. There are several functions in pcre_compile() that scan along a compiled
550        expression for various reasons (e.g. to see if it's fixed length for look
551        behind). There were bugs in these functions when a repeated \p or \P was
552        present in the pattern. These operators have additional parameters compared
553        with \d, etc, and these were not being taken into account when moving along
554        the compiled data. Specifically:
556        (a) A item such as \p{Yi}{3} in a lookbehind was not treated as fixed
557            length.
559        (b) An item such as \pL+ within a repeated group could cause crashes or
560            loops.
562        (c) A pattern such as \p{Yi}+(\P{Yi}+)(?1) could give an incorrect
563            "reference to non-existent subpattern" error.
565        (d) A pattern like (\P{Yi}{2}\277)? could loop at compile time.
567    24. A repeated \S or \W in UTF-8 mode could give wrong answers when multibyte
568        characters were involved (for example /\S{2}/8g with "A\x{a3}BC").
570    25. Using pcregrep in multiline, inverted mode (-Mv) caused it to loop.
572    26. Patterns such as [\P{Yi}A] which include \p or \P and just one other
573        character were causing crashes (broken optimization).
575    27. Patterns such as (\P{Yi}*\277)* (group with possible zero repeat containing
576        \p or \P) caused a compile-time loop.
578    28. More problems have arisen in unanchored patterns when CRLF is a valid line
579        break. For example, the unstudied pattern [\r\n]A does not match the string
580        "\r\nA" because change 7.0/46 below moves the current point on by two
581        characters after failing to match at the start. However, the pattern \nA
582        *does* match, because it doesn't start till \n, and if [\r\n]A is studied,
583        the same is true. There doesn't seem any very clean way out of this, but
584        what I have chosen to do makes the common cases work: PCRE now takes note
585        of whether there can be an explicit match for \r or \n anywhere in the
586        pattern, and if so, 7.0/46 no longer applies. As part of this change,
587        there's a new PCRE_INFO_HASCRORLF option for finding out whether a compiled
588        pattern has explicit CR or LF references.
590    29. Added (*CR) etc for changing newline setting at start of pattern.
593    Version 7.2 19-Jun-07
594    ---------------------
596     1. If the fr_FR locale cannot be found for test 3, try the "french" locale,
597        which is apparently normally available under Windows.
599     2. Re-jig the pcregrep tests with different newline settings in an attempt
600        to make them independent of the local environment's newline setting.
602     3. Add code to configure.ac to remove -g from the CFLAGS default settings.
604     4. Some of the "internals" tests were previously cut out when the link size
605        was not 2, because the output contained actual offsets. The recent new
606        "Z" feature of pcretest means that these can be cut out, making the tests
607        usable with all link sizes.
609     5. Implemented Stan Switzer's goto replacement for longjmp() when not using
610        stack recursion. This gives a massive performance boost under BSD, but just
611        a small improvement under Linux. However, it saves one field in the frame
612        in all cases.
614     6. Added more features from the forthcoming Perl 5.10:
616        (a) (?-n) (where n is a string of digits) is a relative subroutine or
617            recursion call. It refers to the nth most recently opened parentheses.
619        (b) (?+n) is also a relative subroutine call; it refers to the nth next
620            to be opened parentheses.
622        (c) Conditions that refer to capturing parentheses can be specified
623            relatively, for example, (?(-2)... or (?(+3)...
625        (d) \K resets the start of the current match so that everything before
626            is not part of it.
628        (e) \k{name} is synonymous with \k<name> and \k'name' (.NET compatible).
630        (f) \g{name} is another synonym - part of Perl 5.10's unification of
631            reference syntax.
633        (g) (?| introduces a group in which the numbering of parentheses in each
634            alternative starts with the same number.
636        (h) \h, \H, \v, and \V match horizontal and vertical whitespace.
638     7. Added two new calls to pcre_fullinfo(): PCRE_INFO_OKPARTIAL and
641     8. A pattern such as  (.*(.)?)*  caused pcre_exec() to fail by either not
642        terminating or by crashing. Diagnosed by Viktor Griph; it was in the code
643        for detecting groups that can match an empty string.
645     9. A pattern with a very large number of alternatives (more than several
646        hundred) was running out of internal workspace during the pre-compile
647        phase, where pcre_compile() figures out how much memory will be needed. A
648        bit of new cunning has reduced the workspace needed for groups with
649        alternatives. The 1000-alternative test pattern now uses 12 bytes of
650        workspace instead of running out of the 4096 that are available.
652    10. Inserted some missing (unsigned int) casts to get rid of compiler warnings.
654    11. Applied patch from Google to remove an optimization that didn't quite work.
655        The report of the bug said:
657          pcrecpp::RE("a*").FullMatch("aaa") matches, while
658          pcrecpp::RE("a*?").FullMatch("aaa") does not, and
659          pcrecpp::RE("a*?\\z").FullMatch("aaa") does again.
661    12. If \p or \P was used in non-UTF-8 mode on a character greater than 127
662        it matched the wrong number of bytes.
665    Version 7.1 24-Apr-07
666    ---------------------
668     1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
669        that is more "standard", making use of automake and other Autotools. There
670        is some re-arrangement of the files and adjustment of comments consequent
671        on this.
673     2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
674        for recursive directory scanning broke on some systems because the files
675        are not scanned in any specific order and on different systems the order
676        was different. A call to "sort" has been inserted into RunGrepTest for the
677        approprate test as a short-term fix. In the longer term there may be an
678        alternative.
680     3. I had an email from Eric Raymond about problems translating some of PCRE's
681        man pages to HTML (despite the fact that I distribute HTML pages, some
682        people do their own conversions for various reasons). The problems
683        concerned the use of low-level troff macros .br and .in. I have therefore
684        removed all such uses from the man pages (some were redundant, some could
685        be replaced by .nf/.fi pairs). The 132html script that I use to generate
686        HTML has been updated to handle .nf/.fi and to complain if it encounters
687        .br or .in.
689     4. Updated comments in configure.ac that get placed in config.h.in and also
690        arranged for config.h to be included in the distribution, with the name
691        config.h.generic, for the benefit of those who have to compile without
692        Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
694     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
695        Weber: (1) pcre_internal.h was missing some function renames; (2) updated
696        makevp.bat for the current PCRE, using the additional files
697        makevp_c.txt, makevp_l.txt, and pcregexp.pas.
699     6. A Windows user reported a minor discrepancy with test 2, which turned out
700        to be caused by a trailing space on an input line that had got lost in his
701        copy. The trailing space was an accident, so I've just removed it.
703     7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
704        that is needed.
706     8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
707        as "const" (a) because they are and (b) because it helps the PHP
708        maintainers who have recently made a script to detect big data structures
709        in the php code that should be moved to the .rodata section. I remembered
710        to update Builducptable as well, so it won't revert if ucptable.h is ever
711        re-created.
713     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
714        pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
715        order to be able to cut out the UTF-8 tables in the latter when UTF-8
716        support is not required. This saves 1.5-2K of code, which is important in
717        some applications.
719        Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
720        so as not to refer to the tables, even though these functions will never be
721        called when UTF-8 support is disabled. Otherwise there are problems with a
722        shared library.
724    10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
726        (a) It was defining its arguments as char * instead of void *.
728        (b) It was assuming that all moves were upwards in memory; this was true
729            a long time ago when I wrote it, but is no longer the case.
731        The emulated memove() is provided for those environments that have neither
732        memmove() nor bcopy(). I didn't think anyone used it these days, but that
733        is clearly not the case, as these two bugs were recently reported.
735    11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
736        and Detrail to create the HTML documentation, the .txt form of the man
737        pages, and it removes trailing spaces from listed files. It also creates
738        pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
739        case, it wraps all the #defines with #ifndefs. This script should be run
740        before "make dist".
742    12. Fixed two fairly obscure bugs concerned with quantified caseless matching
743        with Unicode property support.
745        (a) For a maximizing quantifier, if the two different cases of the
746            character were of different lengths in their UTF-8 codings (there are
747            some cases like this - I found 11), and the matching function had to
748            back up over a mixture of the two cases, it incorrectly assumed they
749            were both the same length.
751        (b) When PCRE was configured to use the heap rather than the stack for
752            recursion during matching, it was not correctly preserving the data for
753            the other case of a UTF-8 character when checking ahead for a match
754            while processing a minimizing repeat. If the check also involved
755            matching a wide character, but failed, corruption could cause an
756            erroneous result when trying to check for a repeat of the original
757            character.
759    13. Some tidying changes to the testing mechanism:
761        (a) The RunTest script now detects the internal link size and whether there
762            is UTF-8 and UCP support by running ./pcretest -C instead of relying on
763            values substituted by "configure". (The RunGrepTest script already did
764            this for UTF-8.) The configure.ac script no longer substitutes the
765            relevant variables.
767        (b) The debugging options /B and /D in pcretest show the compiled bytecode
768            with length and offset values. This means that the output is different
769            for different internal link sizes. Test 2 is skipped for link sizes
770            other than 2 because of this, bypassing the problem. Unfortunately,
771            there was also a test in test 3 (the locale tests) that used /B and
772            failed for link sizes other than 2. Rather than cut the whole test out,
773            I have added a new /Z option to pcretest that replaces the length and
774            offset values with spaces. This is now used to make test 3 independent
775            of link size. (Test 2 will be tidied up later.)
777    14. If erroroffset was passed as NULL to pcre_compile, it provoked a
778        segmentation fault instead of returning the appropriate error message.
780    15. In multiline mode when the newline sequence was set to "any", the pattern
781        ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
782        This doesn't seem right; it now treats the CRLF combination as the line
783        ending, and so does not match in that case. It's only a pattern such as ^$
784        that would hit this one: something like ^ABC$ would have failed after \r
785        and then tried again after \r\n.
787    16. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
788        in an attempt to make files that differ only in their line terminators
789        compare equal. This works on Linux.
791    17. Under certain error circumstances pcregrep might try to free random memory
792        as it exited. This is now fixed, thanks to valgrind.
794    19. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
795        "abc\r\n\r\n", it found an unwanted second match after the second \r. This
796        was because its rules for how to advance for /g after matching an empty
797        string at the end of a line did not allow for this case. They now check for
798        it specially.
800    20. pcretest is supposed to handle patterns and data of any length, by
801        extending its buffers when necessary. It was getting this wrong when the
802        buffer for a data line had to be extended.
804    21. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or
805        CRLF as a newline sequence.
807    22. Code for handling Unicode properties in pcre_dfa_exec() wasn't being cut
808        out by #ifdef SUPPORT_UCP. This did no harm, as it could never be used, but
809        I have nevertheless tidied it up.
811    23. Added some casts to kill warnings from HP-UX ia64 compiler.
813    24. Added a man page for pcre-config.
816    Version 7.0 19-Dec-06
817    ---------------------
819     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
820        moving to gcc 4.1.1.
822     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
823        sys/time.h, which is documented as needed for this function. It doesn't
824        seem to matter on Linux, but it showed up on some releases of OS X.
826     3. It seems that there are systems where bytes whose values are greater than
827        127 match isprint() in the "C" locale. The "C" locale should be the
828        default when a C program starts up. In most systems, only ASCII printing
829        characters match isprint(). This difference caused the output from pcretest
830        to vary, making some of the tests fail. I have changed pcretest so that:
832        (a) When it is outputting text in the compiled version of a pattern, bytes
833            other than 32-126 are always shown as hex escapes.
835        (b) When it is outputting text that is a matched part of a subject string,
836            it does the same, unless a different locale has been set for the match
837            (using the /L modifier). In this case, it uses isprint() to decide.
839     4. Fixed a major bug that caused incorrect computation of the amount of memory
840        required for a compiled pattern when options that changed within the
841        pattern affected the logic of the preliminary scan that determines the
842        length. The relevant options are -x, and -i in UTF-8 mode. The result was
843        that the computed length was too small. The symptoms of this bug were
844        either the PCRE error "internal error: code overflow" from pcre_compile(),
845        or a glibc crash with a message such as "pcretest: free(): invalid next
846        size (fast)". Examples of patterns that provoked this bug (shown in
847        pcretest format) are:
849          /(?-x: )/x
850          /(?x)(?-x: \s*#\s*)/
851          /((?i)[\x{c0}])/8
852          /(?i:[\x{c0}])/8
854        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
855        is now done differently.
857     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
858        wrapper classes; (b) implement a new function in the C++ scanner that is
859        more efficient than the old way of doing things because it avoids levels of
860        recursion in the regex matching; (c) add a paragraph to the documentation
861        for the FullMatch() function.
863     6. The escape sequence \n was being treated as whatever was defined as
864        "newline". Not only was this contrary to the documentation, which states
865        that \n is character 10 (hex 0A), but it also went horribly wrong when
866        "newline" was defined as CRLF. This has been fixed.
868     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
869        was being set to -1 for the "end of line" case (supposedly a value that no
870        character can have). Though this value is never used (the check for end of
871        line is "zero bytes in current character"), it caused compiler complaints.
872        I've changed it to 0xffffffff.
874     8. In pcre_version.c, the version string was being built by a sequence of
875        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
876        string (as it is for production releases) called a macro with an empty
877        argument. The C standard says the result of this is undefined. The gcc
878        compiler treats it as an empty string (which was what was wanted) but it is
879        reported that Visual C gives an error. The source has been hacked around to
880        avoid this problem.
882     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
883        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
884        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
885        of them did).
887    10. Originally, pcretest opened its input and output without "b"; then I was
888        told that "b" was needed in some environments, so it was added for release
889        5.0 to both the input and output. (It makes no difference on Unix-like
890        systems.) Later I was told that it is wrong for the input on Windows. I've
891        now abstracted the modes into two macros, to make it easier to fiddle with
892        them, and removed "b" from the input mode under Windows.
894    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
896    12. Added -help and --help to pcretest as an official way of being reminded
897        of the options.
899    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
900        and pcrecpp.cc because they annoy compilers at high warning levels.
902    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
904    15. Fixed an occurrence of == in configure.ac that should have been = (shell
905        scripts are not C programs :-) and which was not noticed because it works
906        on Linux.
908    16. pcretest is supposed to handle any length of pattern and data line (as one
909        line or as a continued sequence of lines) by extending its input buffer if
910        necessary. This feature was broken for very long pattern lines, leading to
911        a string of junk being passed to pcre_compile() if the pattern was longer
912        than about 50K.
914    17. I have done a major re-factoring of the way pcre_compile() computes the
915        amount of memory needed for a compiled pattern. Previously, there was code
916        that made a preliminary scan of the pattern in order to do this. That was
917        OK when PCRE was new, but as the facilities have expanded, it has become
918        harder and harder to keep it in step with the real compile phase, and there
919        have been a number of bugs (see for example, 4 above). I have now found a
920        cunning way of running the real compile function in a "fake" mode that
921        enables it to compute how much memory it would need, while actually only
922        ever using a few hundred bytes of working memory and without too many
923        tests of the mode. This should make future maintenance and development
924        easier. A side effect of this work is that the limit of 200 on the nesting
925        depth of parentheses has been removed (though this was never a serious
926        limitation, I suspect). However, there is a downside: pcre_compile() now
927        runs more slowly than before (30% or more, depending on the pattern). I
928        hope this isn't a big issue. There is no effect on runtime performance.
930    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
931        newline (only possible for the last line of a file) and it was a
932        pattern that set a locale (followed by /Lsomething), pcretest crashed.
934    19. Added additional timing features to pcretest. (1) The -tm option now times
935        matching only, not compiling. (2) Both -t and -tm can be followed, as a
936        separate command line item, by a number that specifies the number of
937        repeats to use when timing. The default is 50000; this gives better
938        precision, but takes uncomfortably long for very large patterns.
940    20. Extended pcre_study() to be more clever in cases where a branch of a
941        subpattern has no definite first character. For example, (a*|b*)[cd] would
942        previously give no result from pcre_study(). Now it recognizes that the
943        first character must be a, b, c, or d.
945    21. There was an incorrect error "recursive call could loop indefinitely" if
946        a subpattern (or the entire pattern) that was being tested for matching an
947        empty string contained only one non-empty item after a nested subpattern.
948        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
949        incorrectly, because the \d was being skipped in the check.
951    22. The pcretest program now has a new pattern option /B and a command line
952        option -b, which is equivalent to adding /B to every pattern. This causes
953        it to show the compiled bytecode, without the additional information that
954        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
955        is the same as /B/I).
957    23. A new optimization is now able automatically to treat some sequences such
958        as a*b as a*+b. More specifically, if something simple (such as a character
959        or a simple class like \d) has an unlimited quantifier, and is followed by
960        something that cannot possibly match the quantified thing, the quantifier
961        is automatically "possessified".
963    24. A recursive reference to a subpattern whose number was greater than 39
964        went wrong under certain circumstances in UTF-8 mode. This bug could also
965        have affected the operation of pcre_study().
967    25. Realized that a little bit of performance could be had by replacing
968        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
970    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
972    27. Possessive quantifiers such as a++ were previously implemented by turning
973        them into atomic groups such as ($>a+). Now they have their own opcodes,
974        which improves performance. This includes the automatically created ones
975        from 23 above.
977    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
978        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
979        the first matched character to be a colon. This applied both to named and
980        numbered groups.
982    29. The ucpinternal.h header file was missing its idempotency #ifdef.
984    30. I was sent a "project" file called libpcre.a.dev which I understand makes
985        building PCRE on Windows easier, so I have included it in the distribution.
987    31. There is now a check in pcretest against a ridiculously large number being
988        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
989        loop, the loop is abandoned.
991    32. Forward references to subpatterns in conditions such as (?(2)...) where
992        subpattern 2 is defined later cause pcre_compile() to search forwards in
993        the pattern for the relevant set of parentheses. This search went wrong
994        when there were unescaped parentheses in a character class, parentheses
995        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
997    33. "Subroutine" calls and backreferences were previously restricted to
998        referencing subpatterns earlier in the regex. This restriction has now
999        been removed.
1001    34. Added a number of extra features that are going to be in Perl 5.10. On the
1002        whole, these are just syntactic alternatives for features that PCRE had
1003        previously implemented using the Python syntax or my own invention. The
1004        other formats are all retained for compatibility.
1006        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
1007            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
1008            also .NET compatible.
1010        (b) A recursion or subroutine call to a named group can now be defined as
1011            (?&name) as well as (?P>name).
1013        (c) A backreference to a named group can now be defined as \k<name> or
1014            \k'name' as well as (?P=name). The new forms, as well as being in Perl
1015            5.10, are also .NET compatible.
1017        (d) A conditional reference to a named group can now use the syntax
1018            (?(<name>) or (?('name') as well as (?(name).
1020        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
1021            groups (named and numbered) that are never evaluated inline, but can be
1022            called as "subroutines" from elsewhere. In effect, the DEFINE condition
1023            is always false. There may be only one alternative in such a group.
1025        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
1026            as the simple (?(R). The condition is true only if the most recent
1027            recursion is that of the given number or name. It does not search out
1028            through the entire recursion stack.
1030        (g) The escape \gN or \g{N} has been added, where N is a positive or
1031            negative number, specifying an absolute or relative reference.
1033    35. Tidied to get rid of some further signed/unsigned compiler warnings and
1034        some "unreachable code" warnings.
1036    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
1037        things, this adds five new scripts.
1039    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
1040        There were also incompatibilities regarding the handling of \Q..\E inside
1041        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
1042        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
1044    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
1045        matches an empty string, and forcibly breaks the loop. There were bugs in
1046        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
1047        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
1048        separate and independent bugs (that affected different cases) have been
1049        fixed.
1051    39. Refactored the code to abolish the use of different opcodes for small
1052        capturing bracket numbers. This is a tidy that I avoided doing when I
1053        removed the limit on the number of capturing brackets for 3.5 back in 2001.
1054        The new approach is not only tidier, it makes it possible to reduce the
1055        memory needed to fix the previous bug (38).
1057    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
1058        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
1059        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
1060        mode.
1062    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
1063        report.
1065    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
1066        copy construction and assignment in the C++ wrapper.
1068    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
1069        couple of bugs that could have given wrong results in the "--newline=crlf"
1070        case.
1072    44. Added a number of casts and did some reorganization of signed/unsigned int
1073        variables following suggestions from Dair Grant. Also renamed the variable
1074        "this" as "item" because it is a C++ keyword.
1076    45. Arranged for dftables to add
1078          #include "pcre_internal.h"
1080        to pcre_chartables.c because without it, gcc 4.x may remove the array
1081        definition from the final binary if PCRE is built into a static library and
1082        dead code stripping is activated.
1084    46. For an unanchored pattern, if a match attempt fails at the start of a
1085        newline sequence, and the newline setting is CRLF or ANY, and the next two
1086        characters are CRLF, advance by two characters instead of one.
1089    Version 6.7 04-Jul-06
1090    ---------------------
1092     1. In order to handle tests when input lines are enormously long, pcretest has
1093        been re-factored so that it automatically extends its buffers when
1094        necessary. The code is crude, but this _is_ just a test program. The
1095        default size has been increased from 32K to 50K.
1097     2. The code in pcre_study() was using the value of the re argument before
1098        testing it for NULL. (Of course, in any sensible call of the function, it
1099        won't be NULL.)
1101     3. The memmove() emulation function in pcre_internal.h, which is used on
1102        systems that lack both memmove() and bcopy() - that is, hardly ever -
1103        was missing a "static" storage class specifier.
1105     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
1106        containing an extended class (one that cannot be represented by a bitmap
1107        because it contains high-valued characters or Unicode property items, e.g.
1108        [\pZ]). Almost always one would set UTF-8 mode when processing such a
1109        pattern, but PCRE should not loop if you do not (it no longer does).
1110        [Detail: two cases were found: (a) a repeated subpattern containing an
1111        extended class; (b) a recursive reference to a subpattern that followed a
1112        previous extended class. It wasn't skipping over the extended class
1113        correctly when UTF-8 mode was not set.]
1115     5. A negated single-character class was not being recognized as fixed-length
1116        in lookbehind assertions such as (?<=[^f]), leading to an incorrect
1117        compile error "lookbehind assertion is not fixed length".
1119     6. The RunPerlTest auxiliary script was showing an unexpected difference
1120        between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
1121        write a Perl script that can interpret lines of an input file either as
1122        byte characters or as UTF-8, which is what "perltest" was being required to
1123        do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
1124        can't do is switch easily at run time between having the "use utf8;" pragma
1125        or not. In the end, I fudged it by using the RunPerlTest script to insert
1126        "use utf8;" explicitly for the UTF-8 tests.
1128     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
1129        the end of the subject string, contrary to the documentation and to what
1130        Perl does. This was true of both matching functions. Now it matches only at
1131        the start of the subject and immediately after *internal* newlines.
1133     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
1134        a pointer to an int instead of a pointer to an unsigned long int. This
1135        caused problems on 64-bit systems.
1137     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
1138        instance of the 'standard' template library not being so standard".
1140    10. There was no check on the number of named subpatterns nor the maximum
1141        length of a subpattern name. The product of these values is used to compute
1142        the size of the memory block for a compiled pattern. By supplying a very
1143        long subpattern name and a large number of named subpatterns, the size
1144        computation could be caused to overflow. This is now prevented by limiting
1145        the length of names to 32 characters, and the number of named subpatterns
1146        to 10,000.
1148    11. Subpatterns that are repeated with specific counts have to be replicated in
1149        the compiled pattern. The size of memory for this was computed from the
1150        length of the subpattern and the repeat count. The latter is limited to
1151        65535, but there was no limit on the former, meaning that integer overflow
1152        could in principle occur. The compiled length of a repeated subpattern is
1153        now limited to 30,000 bytes in order to prevent this.
1155    12. Added the optional facility to have named substrings with the same name.
1157    13. Added the ability to use a named substring as a condition, using the
1158        Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
1159        are numbers (not recommended). Forward references are permitted.
1161    14. Added forward references in named backreferences (if you see what I mean).
1163    15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
1164        pattern could run off the end of the subject. For example, the pattern
1165        "(?s)(.{1,5})"8 did this with the subject "ab".
1167    16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
1168        PCRE_CASELESS was set when matching characters that were quantified with ?
1169        or *.
1171    17. A character class other than a single negated character that had a minimum
1172        but no maximum quantifier - for example [ab]{6,} - was not handled
1173        correctly by pce_dfa_exec(). It would match only one character.
1175    18. A valid (though odd) pattern that looked like a POSIX character
1176        class but used an invalid character after [ (for example [[,abc,]]) caused
1177        pcre_compile() to give the error "Failed: internal error: code overflow" or
1178        in some cases to crash with a glibc free() error. This could even happen if
1179        the pattern terminated after [[ but there just happened to be a sequence of
1180        letters, a binary zero, and a closing ] in the memory that followed.
1182    19. Perl's treatment of octal escapes in the range \400 to \777 has changed
1183        over the years. Originally (before any Unicode support), just the bottom 8
1184        bits were taken. Thus, for example, \500 really meant \100. Nowadays the
1185        output from "man perlunicode" includes this:
1187          The regular expression compiler produces polymorphic opcodes.  That
1188          is, the pattern adapts to the data and automatically switches to
1189          the Unicode character scheme when presented with Unicode data--or
1190          instead uses a traditional byte scheme when presented with byte
1191          data.
1193        Sadly, a wide octal escape does not cause a switch, and in a string with
1194        no other multibyte characters, these octal escapes are treated as before.
1195        Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
1196        /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
1197        Unicode string.
1199        I have not perpetrated such confusion in PCRE. Up till now, it took just
1200        the bottom 8 bits, as in old Perl. I have now made octal escapes with
1201        values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
1202        translate to the appropriate multibyte character.
1204    29. Applied some refactoring to reduce the number of warnings from Microsoft
1205        and Borland compilers. This has included removing the fudge introduced
1206        seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
1207        a warning about an unused variable.
1209    21. PCRE has not included VT (character 0x0b) in the set of whitespace
1210        characters since release 4.0, because Perl (from release 5.004) does not.
1211        [Or at least, is documented not to: some releases seem to be in conflict
1212        with the documentation.] However, when a pattern was studied with
1213        pcre_study() and all its branches started with \s, PCRE still included VT
1214        as a possible starting character. Of course, this did no harm; it just
1215        caused an unnecessary match attempt.
1217    22. Removed a now-redundant internal flag bit that recorded the fact that case
1218        dependency changed within the pattern. This was once needed for "required
1219        byte" processing, but is no longer used. This recovers a now-scarce options
1220        bit. Also moved the least significant internal flag bit to the most-
1221        significant bit of the word, which was not previously used (hangover from
1222        the days when it was an int rather than a uint) to free up another bit for
1223        the future.
1225    23. Added support for CRLF line endings as well as CR and LF. As well as the
1226        default being selectable at build time, it can now be changed at runtime
1227        via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
1228        specify that it is scanning data with non-default line endings.
1230    24. Changed the definition of CXXLINK to make it agree with the definition of
1231        LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
1233    25. Applied Ian Taylor's patches to avoid using another stack frame for tail
1234        recursions. This makes a big different to stack usage for some patterns.
1236    26. If a subpattern containing a named recursion or subroutine reference such
1237        as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
1238        the space required for the compiled pattern went wrong and gave too small a
1239        value. Depending on the environment, this could lead to "Failed: internal
1240        error: code overflow at offset 49" or "glibc detected double free or
1241        corruption" errors.
1243    27. Applied patches from Google (a) to support the new newline modes and (b) to
1244        advance over multibyte UTF-8 characters in GlobalReplace.
1246    28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
1247        difference for some implementation of PCRE in some Windows version.
1249    29. Added some extra testing facilities to pcretest:
1251        \q<number>   in a data line sets the "match limit" value
1252        \Q<number>   in a data line sets the "match recursion limt" value
1253        -S <number>  sets the stack size, where <number> is in megabytes
1255        The -S option isn't available for Windows.
1258    Version 6.6 06-Feb-06
1259    ---------------------
1261     1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
1262        in pcreposix.h. I have copied the definition from pcre.h.
1264     2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
1265        because pcre.h is no longer a built file.
1267     3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
1268        not normally included in the compiled code.
1271    Version 6.5 01-Feb-06
1272    ---------------------
1274     1. When using the partial match feature with pcre_dfa_exec(), it was not
1275        anchoring the second and subsequent partial matches at the new starting
1276        point. This could lead to incorrect results. For example, with the pattern
1277        /1234/, partially matching against "123" and then "a4" gave a match.
1279     2. Changes to pcregrep:
1281        (a) All non-match returns from pcre_exec() were being treated as failures
1282            to match the line. Now, unless the error is PCRE_ERROR_NOMATCH, an
1283            error message is output. Some extra information is given for the
1284            PCRE_ERROR_MATCHLIMIT and PCRE_ERROR_RECURSIONLIMIT errors, which are
1285            probably the only errors that are likely to be caused by users (by
1286            specifying a regex that has nested indefinite repeats, for instance).
1287            If there are more than 20 of these errors, pcregrep is abandoned.
1289        (b) A binary zero was treated as data while matching, but terminated the
1290            output line if it was written out. This has been fixed: binary zeroes
1291            are now no different to any other data bytes.
1293        (c) Whichever of the LC_ALL or LC_CTYPE environment variables is set is
1294            used to set a locale for matching. The --locale=xxxx long option has
1295            been added (no short equivalent) to specify a locale explicitly on the
1296            pcregrep command, overriding the environment variables.
1298        (d) When -B was used with -n, some line numbers in the output were one less
1299            than they should have been.
1301        (e) Added the -o (--only-matching) option.
1303        (f) If -A or -C was used with -c (count only), some lines of context were
1304            accidentally printed for the final match.
1306        (g) Added the -H (--with-filename) option.
1308        (h) The combination of options -rh failed to suppress file names for files
1309            that were found from directory arguments.
1311        (i) Added the -D (--devices) and -d (--directories) options.
1313        (j) Added the -F (--fixed-strings) option.
1315        (k) Allow "-" to be used as a file name for -f as well as for a data file.
1317        (l) Added the --colo(u)r option.
1319        (m) Added Jeffrey Friedl's -S testing option, but within #ifdefs so that it
1320            is not present by default.
1322     3. A nasty bug was discovered in the handling of recursive patterns, that is,
1323        items such as (?R) or (?1), when the recursion could match a number of
1324        alternatives. If it matched one of the alternatives, but subsequently,
1325        outside the recursion, there was a failure, the code tried to back up into
1326        the recursion. However, because of the way PCRE is implemented, this is not
1327        possible, and the result was an incorrect result from the match.
1329        In order to prevent this happening, the specification of recursion has
1330        been changed so that all such subpatterns are automatically treated as
1331        atomic groups. Thus, for example, (?R) is treated as if it were (?>(?R)).
1333     4. I had overlooked the fact that, in some locales, there are characters for
1334        which isalpha() is true but neither isupper() nor islower() are true. In
1335        the fr_FR locale, for instance, the \xAA and \xBA characters (ordmasculine
1336        and ordfeminine) are like this. This affected the treatment of \w and \W
1337        when they appeared in character classes, but not when they appeared outside
1338        a character class. The bit map for "word" characters is now created
1339        separately from the results of isalnum() instead of just taking it from the
1340        upper, lower, and digit maps. (Plus the underscore character, of course.)
1342     5. The above bug also affected the handling of POSIX character classes such as
1343        [[:alpha:]] and [[:alnum:]]. These do not have their own bit maps in PCRE's
1344        permanent tables. Instead, the bit maps for such a class were previously
1345        created as the appropriate unions of the upper, lower, and digit bitmaps.
1346        Now they are created by subtraction from the [[:word:]] class, which has
1347        its own bitmap.
1349     6. The [[:blank:]] character class matches horizontal, but not vertical space.
1350        It is created by subtracting the vertical space characters (\x09, \x0a,
1351        \x0b, \x0c) from the [[:space:]] bitmap. Previously, however, the
1352        subtraction was done in the overall bitmap for a character class, meaning
1353        that a class such as [\x0c[:blank:]] was incorrect because \x0c would not
1354        be recognized. This bug has been fixed.
1356     7. Patches from the folks at Google:
1358          (a) pcrecpp.cc: "to handle a corner case that may or may not happen in
1359          real life, but is still worth protecting against".
1361          (b) pcrecpp.cc: "corrects a bug when negative radixes are used with
1362          regular expressions".
1364          (c) pcre_scanner.cc: avoid use of std::count() because not all systems
1365          have it.
1367          (d) Split off pcrecpparg.h from pcrecpp.h and had the former built by
1368          "configure" and the latter not, in order to fix a problem somebody had
1369          with compiling the Arg class on HP-UX.
1371          (e) Improve the error-handling of the C++ wrapper a little bit.
1373          (f) New tests for checking recursion limiting.
1375     8. The pcre_memmove() function, which is used only if the environment does not
1376        have a standard memmove() function (and is therefore rarely compiled),
1377        contained two bugs: (a) use of int instead of size_t, and (b) it was not
1378        returning a result (though PCRE never actually uses the result).
1380     9. In the POSIX regexec() interface, if nmatch is specified as a ridiculously
1381        large number - greater than INT_MAX/(3*sizeof(int)) - REG_ESPACE is
1382        returned instead of calling malloc() with an overflowing number that would
1383        most likely cause subsequent chaos.
1385    10. The debugging option of pcretest was not showing the NO_AUTO_CAPTURE flag.
1387    11. The POSIX flag REG_NOSUB is now supported. When a pattern that was compiled
1388        with this option is matched, the nmatch and pmatch options of regexec() are
1389        ignored.
1391    12. Added REG_UTF8 to the POSIX interface. This is not defined by POSIX, but is
1392        provided in case anyone wants to the the POSIX interface with UTF-8
1393        strings.
1395    13. Added CXXLDFLAGS to the Makefile parameters to provide settings only on the
1396        C++ linking (needed for some HP-UX environments).
1398    14. Avoid compiler warnings in get_ucpname() when compiled without UCP support
1399        (unused parameter) and in the pcre_printint() function (omitted "default"
1400        switch label when the default is to do nothing).
1402    15. Added some code to make it possible, when PCRE is compiled as a C++
1403        library, to replace subject pointers for pcre_exec() with a smart pointer
1404        class, thus making it possible to process discontinuous strings.
1406    16. The two macros PCRE_EXPORT and PCRE_DATA_SCOPE are confusing, and perform
1407        much the same function. They were added by different people who were trying
1408        to make PCRE easy to compile on non-Unix systems. It has been suggested
1409        that PCRE_EXPORT be abolished now that there is more automatic apparatus
1410        for compiling on Windows systems. I have therefore replaced it with
1411        PCRE_DATA_SCOPE. This is set automatically for Windows; if not set it
1412        defaults to "extern" for C or "extern C" for C++, which works fine on
1413        Unix-like systems. It is now possible to override the value of PCRE_DATA_
1414        SCOPE with something explicit in config.h. In addition:
1416        (a) pcreposix.h still had just "extern" instead of either of these macros;
1417            I have replaced it with PCRE_DATA_SCOPE.
1419        (b) Functions such as _pcre_xclass(), which are internal to the library,
1420            but external in the C sense, all had PCRE_EXPORT in their definitions.
1421            This is apparently wrong for the Windows case, so I have removed it.
1422            (It makes no difference on Unix-like systems.)
1424    17. Added a new limit, MATCH_LIMIT_RECURSION, which limits the depth of nesting
1425        of recursive calls to match(). This is different to MATCH_LIMIT because
1426        that limits the total number of calls to match(), not all of which increase
1427        the depth of recursion. Limiting the recursion depth limits the amount of
1428        stack (or heap if NO_RECURSE is set) that is used. The default can be set
1429        when PCRE is compiled, and changed at run time. A patch from Google adds
1430        this functionality to the C++ interface.
1432    18. Changes to the handling of Unicode character properties:
1434        (a) Updated the table to Unicode 4.1.0.
1436        (b) Recognize characters that are not in the table as "Cn" (undefined).
1438        (c) I revised the way the table is implemented to a much improved format
1439            which includes recognition of ranges. It now supports the ranges that
1440            are defined in UnicodeData.txt, and it also amalgamates other
1441            characters into ranges. This has reduced the number of entries in the
1442            table from around 16,000 to around 3,000, thus reducing its size
1443            considerably. I realized I did not need to use a tree structure after
1444            all - a binary chop search is just as efficient. Having reduced the
1445            number of entries, I extended their size from 6 bytes to 8 bytes to
1446            allow for more data.
1448        (d) Added support for Unicode script names via properties such as \p{Han}.
1450    19. In UTF-8 mode, a backslash followed by a non-Ascii character was not
1451        matching that character.
1453    20. When matching a repeated Unicode property with a minimum greater than zero,
1454        (for example \pL{2,}), PCRE could look past the end of the subject if it
1455        reached it while seeking the minimum number of characters. This could
1456        happen only if some of the characters were more than one byte long, because
1457        there is a check for at least the minimum number of bytes.
1459    21. Refactored the implementation of \p and \P so as to be more general, to
1460        allow for more different types of property in future. This has changed the
1461        compiled form incompatibly. Anybody with saved compiled patterns that use
1462        \p or \P will have to recompile them.
1464    22. Added "Any" and "L&" to the supported property types.
1466    23. Recognize \x{...} as a code point specifier, even when not in UTF-8 mode,
1467        but give a compile time error if the value is greater than 0xff.
1469    24. The man pages for pcrepartial, pcreprecompile, and pcre_compile2 were
1470        accidentally not being installed or uninstalled.
1472    25. The pcre.h file was built from pcre.h.in, but the only changes that were
1473        made were to insert the current release number. This seemed silly, because
1474        it made things harder for people building PCRE on systems that don't run
1475        "configure". I have turned pcre.h into a distributed file, no longer built
1476        by "configure", with the version identification directly included. There is
1477        no longer a pcre.h.in file.
1479        However, this change necessitated a change to the pcre-config script as
1480        well. It is built from pcre-config.in, and one of the substitutions was the
1481        release number. I have updated configure.ac so that ./configure now finds
1482        the release number by grepping pcre.h.
1484    26. Added the ability to run the tests under valgrind.
1487    Version 6.4 05-Sep-05
1488    ---------------------
1490     1. Change 6.0/10/(l) to pcregrep introduced a bug that caused separator lines
1491        "--" to be printed when multiple files were scanned, even when none of the
1492        -A, -B, or -C options were used. This is not compatible with Gnu grep, so I
1493        consider it to be a bug, and have restored the previous behaviour.
1495     2. A couple of code tidies to get rid of compiler warnings.
1497     3. The pcretest program used to cheat by referring to symbols in the library
1498        whose names begin with _pcre_. These are internal symbols that are not
1499        really supposed to be visible externally, and in some environments it is
1500        possible to suppress them. The cheating is now confined to including
1501        certain files from the library's source, which is a bit cleaner.
1503     4. Renamed pcre.in as pcre.h.in to go with pcrecpp.h.in; it also makes the
1504        file's purpose clearer.
1506     5. Reorganized pcre_ucp_findchar().
1509    Version 6.3 15-Aug-05
1510    ---------------------
1512     1. The file libpcre.pc.in did not have general read permission in the tarball.
1514     2. There were some problems when building without C++ support:
1516        (a) If C++ support was not built, "make install" and "make test" still
1517            tried to test it.
1519        (b) There were problems when the value of CXX was explicitly set. Some
1520            changes have been made to try to fix these, and ...
1522        (c) --disable-cpp can now be used to explicitly disable C++ support.
1524        (d) The use of @CPP_OBJ@ directly caused a blank line preceded by a
1525            backslash in a target when C++ was disabled. This confuses some
1526            versions of "make", apparently. Using an intermediate variable solves
1527            this. (Same for CPP_LOBJ.)
1529     3. $(LINK_FOR_BUILD) now includes $(CFLAGS_FOR_BUILD) and $(LINK)
1530        (non-Windows) now includes $(CFLAGS) because these flags are sometimes
1531        necessary on certain architectures.
1533     4. Added a setting of -export-symbols-regex to the link command to remove
1534        those symbols that are exported in the C sense, but actually are local
1535        within the library, and not documented. Their names all begin with
1536        "_pcre_". This is not a perfect job, because (a) we have to except some
1537        symbols that pcretest ("illegally") uses, and (b) the facility isn't always
1538        available (and never for static libraries). I have made a note to try to
1539        find a way round (a) in the future.
1542    Version 6.2 01-Aug-05
1543    ---------------------
1545     1. There was no test for integer overflow of quantifier values. A construction
1546        such as {1111111111111111} would give undefined results. What is worse, if
1547        a minimum quantifier for a parenthesized subpattern overflowed and became
1548        negative, the calculation of the memory size went wrong. This could have
1549        led to memory overwriting.
1551     2. Building PCRE using VPATH was broken. Hopefully it is now fixed.
1553     3. Added "b" to the 2nd argument of fopen() in dftables.c, for non-Unix-like
1554        operating environments where this matters.
1556     4. Applied Giuseppe Maxia's patch to add additional features for controlling
1557        PCRE options from within the C++ wrapper.
1559     5. Named capturing subpatterns were not being correctly counted when a pattern
1560        was compiled. This caused two problems: (a) If there were more than 100
1561        such subpatterns, the calculation of the memory needed for the whole
1562        compiled pattern went wrong, leading to an overflow error. (b) Numerical
1563        back references of the form \12, where the number was greater than 9, were
1564        not recognized as back references, even though there were sufficient
1565        previous subpatterns.
1567     6. Two minor patches to pcrecpp.cc in order to allow it to compile on older
1568        versions of gcc, e.g. 2.95.4.
1571    Version 6.1 21-Jun-05
1572    ---------------------
1574     1. There was one reference to the variable "posix" in pcretest.c that was not
1575        surrounded by "#if !defined NOPOSIX".
1577     2. Make it possible to compile pcretest without DFA support, UTF8 support, or
1578        the cross-check on the old pcre_info() function, for the benefit of the
1579        cut-down version of PCRE that is currently imported into Exim.
1581     3. A (silly) pattern starting with (?i)(?-i) caused an internal space
1582        allocation error. I've done the easy fix, which wastes 2 bytes for sensible
1583        patterns that start (?i) but I don't think that matters. The use of (?i) is
1584        just an example; this all applies to the other options as well.
1586     4. Since libtool seems to echo the compile commands it is issuing, the output
1587        from "make" can be reduced a bit by putting "@" in front of each libtool
1588        compile command.
1590     5. Patch from the folks at Google for configure.in to be a bit more thorough
1591        in checking for a suitable C++ installation before trying to compile the
1592        C++ stuff. This should fix a reported problem when a compiler was present,
1593        but no suitable headers.
1595     6. The man pages all had just "PCRE" as their title. I have changed them to
1596        be the relevant file name. I have also arranged that these names are
1597        retained in the file doc/pcre.txt, which is a concatenation in text format
1598        of all the man pages except the little individual ones for each function.
1600     7. The NON-UNIX-USE file had not been updated for the different set of source
1601        files that come with release 6. I also added a few comments about the C++
1602        wrapper.
1605    Version 6.0 07-Jun-05
1606    ---------------------
1608     1. Some minor internal re-organization to help with my DFA experiments.
1610     2. Some missing #ifdef SUPPORT_UCP conditionals in pcretest and printint that
1611        didn't matter for the library itself when fully configured, but did matter
1612        when compiling without UCP support, or within Exim, where the ucp files are
1613        not imported.
1615     3. Refactoring of the library code to split up the various functions into
1616        different source modules. The addition of the new DFA matching code (see
1617        below) to a single monolithic source would have made it really too
1618        unwieldy, quite apart from causing all the code to be include in a
1619        statically linked application, when only some functions are used. This is
1620        relevant even without the DFA addition now that patterns can be compiled in
1621        one application and matched in another.
1623        The downside of splitting up is that there have to be some external
1624        functions and data tables that are used internally in different modules of
1625        the library but which are not part of the API. These have all had their
1626        names changed to start with "_pcre_" so that they are unlikely to clash
1627        with other external names.
1629     4. Added an alternate matching function, pcre_dfa_exec(), which matches using
1630        a different (DFA) algorithm. Although it is slower than the original
1631        function, it does have some advantages for certain types of matching
1632        problem.
1634     5. Upgrades to pcretest in order to test the features of pcre_dfa_exec(),
1635        including restarting after a partial match.
1637     6. A patch for pcregrep that defines INVALID_FILE_ATTRIBUTES if it is not
1638        defined when compiling for Windows was sent to me. I have put it into the
1639        code, though I have no means of testing or verifying it.
1641     7. Added the pcre_refcount() auxiliary function.
1643     8. Added the PCRE_FIRSTLINE option. This constrains an unanchored pattern to
1644        match before or at the first newline in the subject string. In pcretest,
1645        the /f option on a pattern can be used to set this.
1647     9. A repeated \w when used in UTF-8 mode with characters greater than 256
1648        would behave wrongly. This has been present in PCRE since release 4.0.
1650    10. A number of changes to the pcregrep command:
1652        (a) Refactored how -x works; insert ^(...)$ instead of setting
1653            PCRE_ANCHORED and checking the length, in preparation for adding
1654            something similar for -w.
1656        (b) Added the -w (match as a word) option.
1658        (c) Refactored the way lines are read and buffered so as to have more
1659            than one at a time available.
1661        (d) Implemented a pcregrep test script.
1663        (e) Added the -M (multiline match) option. This allows patterns to match
1664            over several lines of the subject. The buffering ensures that at least
1665            8K, or the rest of the document (whichever is the shorter) is available
1666            for matching (and similarly the previous 8K for lookbehind assertions).
1668        (f) Changed the --help output so that it now says
1670              -w, --word-regex(p)
1672            instead of two lines, one with "regex" and the other with "regexp"
1673            because that confused at least one person since the short forms are the
1674            same. (This required a bit of code, as the output is generated
1675            automatically from a table. It wasn't just a text change.)
1677        (g) -- can be used to terminate pcregrep options if the next thing isn't an
1678            option but starts with a hyphen. Could be a pattern or a path name
1679            starting with a hyphen, for instance.
1681        (h) "-" can be given as a file name to represent stdin.
1683        (i) When file names are being printed, "(standard input)" is used for
1684            the standard input, for compatibility with GNU grep. Previously
1685            "<stdin>" was used.
1687        (j) The option --label=xxx can be used to supply a name to be used for
1688            stdin when file names are being printed. There is no short form.
1690        (k) Re-factored the options decoding logic because we are going to add
1691            two more options that take data. Such options can now be given in four
1692            different ways, e.g. "-fname", "-f name", "--file=name", "--file name".
1694        (l) Added the -A, -B, and -C options for requesting that lines of context
1695            around matches be printed.
1697        (m) Added the -L option to print the names of files that do not contain
1698            any matching lines, that is, the complement of -l.
1700        (n) The return code is 2 if any file cannot be opened, but pcregrep does
1701            continue to scan other files.
1703        (o) The -s option was incorrectly implemented. For compatibility with other
1704            greps, it now suppresses the error message for a non-existent or non-
1705            accessible file (but not the return code). There is a new option called
1706            -q that suppresses the output of matching lines, which was what -s was
1707            previously doing.
1709        (p) Added --include and --exclude options to specify files for inclusion
1710            and exclusion when recursing.
1712    11. The Makefile was not using the Autoconf-supported LDFLAGS macro properly.
1713        Hopefully, it now does.
1715    12. Missing cast in pcre_study().
1717    13. Added an "uninstall" target to the makefile.
1719    14. Replaced "extern" in the function prototypes in Makefile.in with
1720        "PCRE_DATA_SCOPE", which defaults to 'extern' or 'extern "C"' in the Unix
1721        world, but is set differently for Windows.
1723    15. Added a second compiling function called pcre_compile2(). The only
1724        difference is that it has an extra argument, which is a pointer to an
1725        integer error code. When there is a compile-time failure, this is set
1726        non-zero, in addition to the error test pointer being set to point to an
1727        error message. The new argument may be NULL if no error number is required
1728        (but then you may as well call pcre_compile(), which is now just a
1729        wrapper). This facility is provided because some applications need a
1730        numeric error indication, but it has also enabled me to tidy up the way
1731        compile-time errors are handled in the POSIX wrapper.
1733    16. Added VPATH=.libs to the makefile; this should help when building with one
1734        prefix path and installing with another. (Or so I'm told by someone who
1735        knows more about this stuff than I do.)
1737    17. Added a new option, REG_DOTALL, to the POSIX function regcomp(). This
1738        passes PCRE_DOTALL to the pcre_compile() function, making the "." character
1739        match everything, including newlines. This is not POSIX-compatible, but
1740        somebody wanted the feature. From pcretest it can be activated by using
1741        both the P and the s flags.
1743    18. AC_PROG_LIBTOOL appeared twice in Makefile.in. Removed one.
1745    19. libpcre.pc was being incorrectly installed as executable.
1747    20. A couple of places in pcretest check for end-of-line by looking for '\n';
1748        it now also looks for '\r' so that it will work unmodified on Windows.
1750    21. Added Google's contributed C++ wrapper to the distribution.
1752    22. Added some untidy missing memory free() calls in pcretest, to keep
1753        Electric Fence happy when testing.
1757    Version 5.0 13-Sep-04
1758    ---------------------
1760     1. Internal change: literal characters are no longer packed up into items
1761        containing multiple characters in a single byte-string. Each character
1762        is now matched using a separate opcode. However, there may be more than one
1763        byte in the character in UTF-8 mode.
1765     2. The pcre_callout_block structure has two new fields: pattern_position and
1766        next_item_length. These contain the offset in the pattern to the next match
1767        item, and its length, respectively.
1769     3. The PCRE_AUTO_CALLOUT option for pcre_compile() requests the automatic
1770        insertion of callouts before each pattern item. Added the /C option to
1771        pcretest to make use of this.
1773     4. On the advice of a Windows user, the lines
1775          #if defined(_WIN32) || defined(WIN32)
1776          _setmode( _fileno( stdout ), 0x8000 );
1777          #endif  /* defined(_WIN32) || defined(WIN32) */
1779        have been added to the source of pcretest. This apparently does useful
1780        magic in relation to line terminators.
1782     5. Changed "r" and "w" in the calls to fopen() in pcretest to "rb" and "wb"
1783        for the benefit of those environments where the "b" makes a difference.
1785     6. The icc compiler has the same options as gcc, but "configure" doesn't seem
1786        to know about it. I have put a hack into configure.in that adds in code
1787        to set GCC=yes if CC=icc. This seems to end up at a point in the
1788        generated configure script that is early enough to affect the setting of
1789        compiler options, which is what is needed, but I have no means of testing
1790        whether it really works. (The user who reported this had patched the
1791        generated configure script, which of course I cannot do.)
1793        LATER: After change 22 below (new libtool files), the configure script
1794        seems to know about icc (and also ecc). Therefore, I have commented out
1795        this hack in configure.in.
1797     7. Added support for pkg-config (2 patches were sent in).
1799     8. Negated POSIX character classes that used a combination of internal tables
1800        were completely broken. These were [[:^alpha:]], [[:^alnum:]], and
1801        [[:^ascii]]. Typically, they would match almost any characters. The other
1802        POSIX classes were not broken in this way.
1804     9. Matching the pattern "\b.*?" against "ab cd", starting at offset 1, failed
1805        to find the match, as PCRE was deluded into thinking that the match had to
1806        start at the start point or following a newline. The same bug applied to
1807        patterns with negative forward assertions or any backward assertions
1808        preceding ".*" at the start, unless the pattern required a fixed first
1809        character. This was a failing pattern: "(?!.bcd).*". The bug is now fixed.
1811    10. In UTF-8 mode, when moving forwards in the subject after a failed match
1812        starting at the last subject character, bytes beyond the end of the subject
1813        string were read.
1815    11. Renamed the variable "class" as "classbits" to make life easier for C++
1816        users. (Previously there was a macro definition, but it apparently wasn't
1817        enough.)
1819    12. Added the new field "tables" to the extra data so that tables can be passed
1820        in at exec time, or the internal tables can be re-selected. This allows
1821        a compiled regex to be saved and re-used at a later time by a different
1822        program that might have everything at different addresses.
1824    13. Modified the pcre-config script so that, when run on Solaris, it shows a
1825        -R library as well as a -L library.
1827    14. The debugging options of pcretest (-d on the command line or D on a
1828        pattern) showed incorrect output for anything following an extended class
1829        that contained multibyte characters and which was followed by a quantifier.
1831    15. Added optional support for general category Unicode character properties
1832        via the \p, \P, and \X escapes. Unicode property support implies UTF-8
1833        support. It adds about 90K to the size of the library. The meanings of the
1834        inbuilt class escapes such as \d and \s have NOT been changed.
1836    16. Updated pcredemo.c to include calls to free() to release the memory for the
1837        compiled pattern.
1839    17. The generated file chartables.c was being created in the source directory
1840        instead of in the building directory. This caused the build to fail if the
1841        source directory was different from the building directory, and was
1842        read-only.
1844    18. Added some sample Win commands from Mark Tetrode into the NON-UNIX-USE
1845        file. No doubt somebody will tell me if they don't make sense... Also added
1846        Dan Mooney's comments about building on OpenVMS.
1848    19. Added support for partial matching via the PCRE_PARTIAL option for
1849        pcre_exec() and the \P data escape in pcretest.
1851    20. Extended pcretest with 3 new pattern features:
1853        (i)   A pattern option of the form ">rest-of-line" causes pcretest to
1854              write the compiled pattern to the file whose name is "rest-of-line".
1855              This is a straight binary dump of the data, with the saved pointer to
1856              the character tables forced to be NULL. The study data, if any, is
1857              written too. After writing, pcretest reads a new pattern.
1859        (ii)  If, instead of a pattern, "<rest-of-line" is given, pcretest reads a
1860              compiled pattern from the given file. There must not be any
1861              occurrences of "<" in the file name (pretty unlikely); if there are,
1862              pcretest will instead treat the initial "<" as a pattern delimiter.
1863              After reading in the pattern, pcretest goes on to read data lines as
1864              usual.
1866        (iii) The F pattern option causes pcretest to flip the bytes in the 32-bit
1867              and 16-bit fields in a compiled pattern, to simulate a pattern that
1868              was compiled on a host of opposite endianness.
1870    21. The pcre-exec() function can now cope with patterns that were compiled on
1871        hosts of opposite endianness, with this restriction:
1873          As for any compiled expression that is saved and used later, the tables
1874          pointer field cannot be preserved; the extra_data field in the arguments
1875          to pcre_exec() should be used to pass in a tables address if a value
1876          other than the default internal tables were used at compile time.
1878    22. Calling pcre_exec() with a negative value of the "ovecsize" parameter is
1879        now diagnosed as an error. Previously, most of the time, a negative number
1880        would have been treated as zero, but if in addition "ovector" was passed as
1881        NULL, a crash could occur.
1883    23. Updated the files ltmain.sh, config.sub, config.guess, and aclocal.m4 with
1884        new versions from the libtool 1.5 distribution (the last one is a copy of
1885        a file called libtool.m4). This seems to have fixed the need to patch
1886        "configure" to support Darwin 1.3 (which I used to do). However, I still
1887        had to patch ltmain.sh to ensure that ${SED} is set (it isn't on my
1888        workstation).
1890    24. Changed the PCRE licence to be the more standard "BSD" licence.
1893    Version 4.5 01-Dec-03
1894    ---------------------
1896     1. There has been some re-arrangement of the code for the match() function so
1897        that it can be compiled in a version that does not call itself recursively.
1898        Instead, it keeps those local variables that need separate instances for
1899        each "recursion" in a frame on the heap, and gets/frees frames whenever it
1900        needs to "recurse". Keeping track of where control must go is done by means
1901        of setjmp/longjmp. The whole thing is implemented by a set of macros that
1902        hide most of the details from the main code, and operates only if
1903        NO_RECURSE is defined while compiling pcre.c. If PCRE is built using the
1904        "configure" mechanism, "--disable-stack-for-recursion" turns on this way of
1905        operating.
1907        To make it easier for callers to provide specially tailored get/free
1908        functions for this usage, two new functions, pcre_stack_malloc, and
1909        pcre_stack_free, are used. They are always called in strict stacking order,
1910        and the size of block requested is always the same.
1912        The PCRE_CONFIG_STACKRECURSE info parameter can be used to find out whether
1913        PCRE has been compiled to use the stack or the heap for recursion. The
1914        -C option of pcretest uses this to show which version is compiled.
1916        A new data escape \S, is added to pcretest; it causes the amounts of store
1917        obtained and freed by both kinds of malloc/free at match time to be added
1918        to the output.
1920     2. Changed the locale test to use "fr_FR" instead of "fr" because that's
1921        what's available on my current Linux desktop machine.
1923     3. When matching a UTF-8 string, the test for a valid string at the start has
1924        been extended. If start_offset is not zero, PCRE now checks that it points
1925        to a byte that is the start of a UTF-8 character. If not, it returns
1926        PCRE_ERROR_BADUTF8_OFFSET (-11). Note: the whole string is still checked;
1927        this is necessary because there may be backward assertions in the pattern.
1928        When matching the same subject several times, it may save resources to use
1929        PCRE_NO_UTF8_CHECK on all but the first call if the string is long.
1931     4. The code for checking the validity of UTF-8 strings has been tightened so
1932        that it rejects (a) strings containing 0xfe or 0xff bytes and (b) strings
1933        containing "overlong sequences".
1935     5. Fixed a bug (appearing twice) that I could not find any way of exploiting!
1936        I had written "if ((digitab[*p++] && chtab_digit) == 0)" where the "&&"
1937        should have been "&", but it just so happened that all the cases this let
1938        through by mistake were picked up later in the function.
1940     6. I had used a variable called "isblank" - this is a C99 function, causing
1941        some compilers to warn. To avoid this, I renamed it (as "blankclass").
1943     7. Cosmetic: (a) only output another newline at the end of pcretest if it is
1944        prompting; (b) run "./pcretest /dev/null" at the start of the test script
1945        so the version is shown; (c) stop "make test" echoing "./RunTest".
1947     8. Added patches from David Burgess to enable PCRE to run on EBCDIC systems.
1949     9. The prototype for memmove() for systems that don't have it was using
1950        size_t, but the inclusion of the header that defines size_t was later. I've
1951        moved the #includes for the C headers earlier to avoid this.
1953    10. Added some adjustments to the code to make it easier to compiler on certain
1954        special systems:
1956          (a) Some "const" qualifiers were missing.
1957          (b) Added the macro EXPORT before all exported functions; by default this
1958              is defined to be empty.
1959          (c) Changed the dftables auxiliary program (that builds chartables.c) so
1960              that it reads its output file name as an argument instead of writing
1961              to the standard output and assuming this can be redirected.
1963    11. In UTF-8 mode, if a recursive reference (e.g. (?1)) followed a character
1964        class containing characters with values greater than 255, PCRE compilation
1965        went into a loop.
1967    12. A recursive reference to a subpattern that was within another subpattern
1968        that had a minimum quantifier of zero caused PCRE to crash. For example,
1969        (x(y(?2))z)? provoked this bug with a subject that got as far as the
1970        recursion. If the recursively-called subpattern itself had a zero repeat,
1971        that was OK.
1973    13. In pcretest, the buffer for reading a data line was set at 30K, but the
1974        buffer into which it was copied (for escape processing) was still set at
1975        1024, so long lines caused crashes.
1977    14. A pattern such as /[ab]{1,3}+/ failed to compile, giving the error
1978        "internal error: code overflow...". This applied to any character class
1979        that was followed by a possessive quantifier.
1981    15. Modified the Makefile to add libpcre.la as a prerequisite for
1982        libpcreposix.la because I was told this is needed for a parallel build to
1983        work.
1985    16. If a pattern that contained .* following optional items at the start was
1986        studied, the wrong optimizing data was generated, leading to matching
1987        errors. For example, studying /[ab]*.*c/ concluded, erroneously, that any
1988        matching string must start with a or b or c. The correct conclusion for
1989        this pattern is that a match can start with any character.
1992    Version 4.4 13-Aug-03
1993    ---------------------
1995     1. In UTF-8 mode, a character class containing characters with values between
1996        127 and 255 was not handled correctly if the compiled pattern was studied.
1997        In fixing this, I have also improved the studying algorithm for such
1998        classes (slightly).
2000     2. Three internal functions had redundant arguments passed to them. Removal
2001        might give a very teeny performance improvement.
2003     3. Documentation bug: the value of the capture_top field in a callout is *one
2004        more than* the number of the hightest numbered captured substring.
2006     4. The Makefile linked pcretest and pcregrep with -lpcre, which could result
2007        in incorrectly linking with a previously installed version. They now link
2008        explicitly with libpcre.la.
2010     5. configure.in no longer needs to recognize Cygwin specially.
2012     6. A problem in pcre.in for Windows platforms is fixed.
2014     7. If a pattern was successfully studied, and the -d (or /D) flag was given to
2015        pcretest, it used to include the size of the study block as part of its
2016        output. Unfortunately, the structure contains a field that has a different
2017        size on different hardware architectures. This meant that the tests that
2018        showed this size failed. As the block is currently always of a fixed size,
2019        this information isn't actually particularly useful in pcretest output, so
2020        I have just removed it.
2022     8. Three pre-processor statements accidentally did not start in column 1.
2023        Sadly, there are *still* compilers around that complain, even though
2024        standard C has not required this for well over a decade. Sigh.
2026     9. In pcretest, the code for checking callouts passed small integers in the
2027        callout_data field, which is a void * field. However, some picky compilers
2028        complained about the casts involved for this on 64-bit systems. Now
2029        pcretest passes the address of the small integer instead, which should get
2030        rid of the warnings.
2032    10. By default, when in UTF-8 mode, PCRE now checks for valid UTF-8 strings at
2033        both compile and run time, and gives an error if an invalid UTF-8 sequence
2034        is found. There is a option for disabling this check in cases where the
2035        string is known to be correct and/or the maximum performance is wanted.
2037    11. In response to a bug report, I changed one line in Makefile.in from
2039            -Wl,--out-implib,.libs/lib@WIN_PREFIX@pcreposix.dll.a \
2040        to
2041            -Wl,--out-implib,.libs/@WIN_PREFIX@libpcreposix.dll.a \
2043        to look similar to other lines, but I have no way of telling whether this
2044        is the right thing to do, as I do not use Windows. No doubt I'll get told
2045        if it's wrong...
2048    Version 4.3 21-May-03
2049    ---------------------
2051    1. Two instances of @WIN_PREFIX@ omitted from the Windows targets in the
2052       Makefile.
2054    2. Some refactoring to improve the quality of the code:
2056       (i)   The utf8_table... variables are now declared "const".
2058       (ii)  The code for \cx, which used the "case flipping" table to upper case
2059             lower case letters, now just substracts 32. This is ASCII-specific,
2060             but the whole concept of \cx is ASCII-specific, so it seems
2061             reasonable.
2063       (iii) PCRE was using its character types table to recognize decimal and
2064             hexadecimal digits in the pattern. This is silly, because it handles
2065             only 0-9, a-f, and A-F, but the character types table is locale-
2066             specific, which means strange things might happen. A private
2067             table is now used for this - though it costs 256 bytes, a table is
2068             much faster than multiple explicit tests. Of course, the standard
2069             character types table is still used for matching digits in subject
2070             strings against \d.
2072       (iv)  Strictly, the identifier ESC_t is reserved by POSIX (all identifiers
2073             ending in _t are). So I've renamed it as ESC_tee.
2075    3. The first argument for regexec() in the POSIX wrapper should have been
2076       defined as "const".
2078    4. Changed pcretest to use malloc() for its buffers so that they can be
2079       Electric Fenced for debugging.
2081    5. There were several places in the code where, in UTF-8 mode, PCRE would try
2082       to read one or more bytes before the start of the subject string. Often this
2083       had no effect on PCRE's behaviour, but in some circumstances it could
2084       provoke a segmentation fault.
2086    6. A lookbehind at the start of a pattern in UTF-8 mode could also cause PCRE
2087       to try to read one or more bytes before the start of the subject string.
2089    7. A lookbehind in a pattern matched in non-UTF-8 mode on a PCRE compiled with
2090       UTF-8 support could misbehave in various ways if the subject string
2091       contained bytes with the 0x80 bit set and the 0x40 bit unset in a lookbehind
2092       area. (PCRE was not checking for the UTF-8 mode flag, and trying to move
2093       back over UTF-8 characters.)
2096    Version 4.2 14-Apr-03
2097    ---------------------
2099    1. Typo "#if SUPPORT_UTF8" instead of "#ifdef SUPPORT_UTF8" fixed.
2101    2. Changes to the building process, supplied by Ronald Landheer-Cieslak
2102         [ON_WINDOWS]: new variable, "#" on non-Windows platforms
2103         [NOT_ON_WINDOWS]: new variable, "#" on Windows platforms
2104         [WIN_PREFIX]: new variable, "cyg" for Cygwin
2105         * Makefile.in: use autoconf substitution for OBJEXT, EXEEXT, BUILD_OBJEXT
2106           and BUILD_EXEEXT
2107         Note: automatic setting of the BUILD variables is not yet working
2108         set CPPFLAGS and BUILD_CPPFLAGS (but don't use yet) - should be used at
2109           compile-time but not at link-time
2110         [LINK]: use for linking executables only
2111         make different versions for Windows and non-Windows
2112         [LINKLIB]: new variable, copy of UNIX-style LINK, used for linking
2113           libraries
2114         [LINK_FOR_BUILD]: new variable
2115         [OBJEXT]: use throughout
2116         [EXEEXT]: use throughout
2117         <winshared>: new target
2118         <wininstall>: new target
2119         <dftables.o>: use native compiler
2120         <dftables>: use native linker
2121         <install>: handle Windows platform correctly
2122         <clean>: ditto
2123         <check>: ditto
2124         copy DLL to top builddir before testing
2126       As part of these changes, -no-undefined was removed again. This was reported
2127       to give trouble on HP-UX 11.0, so getting rid of it seems like a good idea
2128       in any case.
2130    3. Some tidies to get rid of compiler warnings:
2132       . In the match_data structure, match_limit was an unsigned long int, whereas
2133         match_call_count was an int. I've made them both unsigned long ints.
2135       . In pcretest the fact that a const uschar * doesn't automatically cast to
2136         a void * provoked a warning.
2138       . Turning on some more compiler warnings threw up some "shadow" variables
2139         and a few more missing casts.
2141    4. If PCRE was complied with UTF-8 support, but called without the PCRE_UTF8
2142       option, a class that contained a single character with a value between 128
2143       and 255 (e.g. /[\xFF]/) caused PCRE to crash.
2145    5. If PCRE was compiled with UTF-8 support, but called without the PCRE_UTF8
2146       option, a class that contained several characters, but with at least one
2147       whose value was between 128 and 255 caused PCRE to crash.
2150    Version 4.1 12-Mar-03
2151    ---------------------
2153    1. Compiling with gcc -pedantic found a couple of places where casts were
2154    needed, and a string in dftables.c that was longer than standard compilers are
2155    required to support.
2157    2. Compiling with Sun's compiler found a few more places where the code could
2158    be tidied up in order to avoid warnings.
2160    3. The variables for cross-compiling were called HOST_CC and HOST_CFLAGS; the
2161    first of these names is deprecated in the latest Autoconf in favour of the name
2162    CC_FOR_BUILD, because "host" is typically used to mean the system on which the
2163    compiled code will be run. I can't find a reference for HOST_CFLAGS, but by
2164    analogy I have changed it to CFLAGS_FOR_BUILD.
2166    4. Added -no-undefined to the linking command in the Makefile, because this is
2167    apparently helpful for Windows. To make it work, also added "-L. -lpcre" to the
2168    linking step for the pcreposix library.
2170    5. PCRE was failing to diagnose the case of two named groups with the same
2171    name.
2173    6. A problem with one of PCRE's optimizations was discovered. PCRE remembers a
2174    literal character that is needed in the subject for a match, and scans along to
2175    ensure that it is present before embarking on the full matching process. This
2176    saves time in cases of nested unlimited repeats that are never going to match.
2177    Problem: the scan can take a lot of time if the subject is very long (e.g.
2178    megabytes), thus penalizing straightforward matches. It is now done only if the
2179    amount of subject to be scanned is less than 1000 bytes.
2181    7. A lesser problem with the same optimization is that it was recording the
2182    first character of an anchored pattern as "needed", thus provoking a search
2183    right along the subject, even when the first match of the pattern was going to
2184    fail. The "needed" character is now not set for anchored patterns, unless it
2185    follows something in the pattern that is of non-fixed length. Thus, it still
2186    fulfils its original purpose of finding quick non-matches in cases of nested
2187    unlimited repeats, but isn't used for simple anchored patterns such as /^abc/.
2190    Version 4.0 17-Feb-03
2191    ---------------------
2193    1. If a comment in an extended regex that started immediately after a meta-item
2194    extended to the end of string, PCRE compiled incorrect data. This could lead to
2195    all kinds of weird effects. Example: /#/ was bad; /()#/ was bad; /a#/ was not.
2197    2. Moved to autoconf 2.53 and libtool 1.4.2.
2199    3. Perl 5.8 no longer needs "use utf8" for doing UTF-8 things. Consequently,
2200    the special perltest8 script is no longer needed - all the tests can be run
2201    from a single perltest script.
2203    4. From 5.004, Perl has not included the VT character (0x0b) in the set defined
2204    by \s. It has now been removed in PCRE. This means it isn't recognized as
2205    whitespace in /x regexes too, which is the same as Perl. Note that the POSIX
2206    class [:space:] *does* include VT, thereby creating a mess.
2208    5. Added the class [:blank:] (a GNU extension from Perl 5.8) to match only
2209    space and tab.
2211    6. Perl 5.005 was a long time ago. It's time to amalgamate the tests that use
2212    its new features into the main test script, reducing the number of scripts.
2214    7. Perl 5.8 has changed the meaning of patterns like /a(?i)b/. Earlier versions
2215    were backward compatible, and made the (?i) apply to the whole pattern, as if
2216    /i were given. Now it behaves more logically, and applies the option setting
2217    only to what follows. PCRE has been changed to follow suit. However, if it
2218    finds options settings right at the start of the pattern, it extracts them into
2219    the global options, as before. Thus, they show up in the info data.
2221    8. Added support for the \Q...\E escape sequence. Characters in between are
2222    treated as literals. This is slightly different from Perl in that $ and @ are
2223    also handled as literals inside the quotes. In Perl, they will cause variable
2224    interpolation. Note the following examples:
2226        Pattern            PCRE matches      Perl matches
2228        \Qabc$xyz\E        abc$xyz           abc followed by the contents of $xyz
2229        \Qabc\$xyz\E       abc\$xyz          abc\$xyz
2230        \Qabc\E\$\Qxyz\E   abc$xyz           abc$xyz
2232    For compatibility with Perl, \Q...\E sequences are recognized inside character
2233    classes as well as outside them.
2235    9. Re-organized 3 code statements in pcretest to avoid "overflow in
2236    floating-point constant arithmetic" warnings from a Microsoft compiler. Added a
2237    (size_t) cast to one statement in pcretest and one in pcreposix to avoid
2238    signed/unsigned warnings.
2240    10. SunOS4 doesn't have strtoul(). This was used only for unpicking the -o
2241    option for pcretest, so I've replaced it by a simple function that does just
2242    that job.
2244    11. pcregrep was ending with code 0 instead of 2 for the commands "pcregrep" or
2245    "pcregrep -".
2247    12. Added "possessive quantifiers" ?+, *+, ++, and {,}+ which come from Sun's
2248    Java package. This provides some syntactic sugar for simple cases of what my
2249    documentation calls "once-only subpatterns". A pattern such as x*+ is the same
2250    as (?>x*). In other words, if what is inside (?>...) is just a single repeated
2251    item, you can use this simplified notation. Note that only makes sense with
2252    greedy quantifiers. Consequently, the use of the possessive quantifier forces
2253    greediness, whatever the setting of the PCRE_UNGREEDY option.
2255    13. A change of greediness default within a pattern was not taking effect at
2256    the current level for patterns like /(b+(?U)a+)/. It did apply to parenthesized
2257    subpatterns that followed. Patterns like /b+(?U)a+/ worked because the option
2258    was abstracted outside.
2260    14. PCRE now supports the \G assertion. It is true when the current matching
2261    position is at the start point of the match. This differs from \A when the
2262    starting offset is non-zero. Used with the /g option of pcretest (or similar
2263    code), it works in the same way as it does for Perl's /g option. If all
2264    alternatives of a regex begin with \G, the expression is anchored to the start
2265    match position, and the "anchored" flag is set in the compiled expression.
2267    15. Some bugs concerning the handling of certain option changes within patterns
2268    have been fixed. These applied to options other than (?ims). For example,
2269    "a(?x: b c )d" did not match "XabcdY" but did match "Xa b c dY". It should have
2270    been the other way round. Some of this was related to change 7 above.
2272    16. PCRE now gives errors for /[.x.]/ and /[=x=]/ as unsupported POSIX
2273    features, as Perl does. Previously, PCRE gave the warnings only for /[[.x.]]/
2274    and /[[=x=]]/. PCRE now also gives an error for /[:name:]/ because it supports
2275    POSIX classes only within a class (e.g. /[[:alpha:]]/).
2277    17. Added support for Perl's \C escape. This matches one byte, even in UTF8
2278    mode. Unlike ".", it always matches newline, whatever the setting of
2279    PCRE_DOTALL. However, PCRE does not permit \C to appear in lookbehind
2280    assertions. Perl allows it, but it doesn't (in general) work because it can't
2281    calculate the length of the lookbehind. At least, that's the case for Perl
2282    5.8.0 - I've been told they are going to document that it doesn't work in
2283    future.
2285    18. Added an error diagnosis for escapes that PCRE does not support: these are
2286    \L, \l, \N, \P, \p, \U, \u, and \X.
2288    19. Although correctly diagnosing a missing ']' in a character class, PCRE was
2289    reading past the end of the pattern in cases such as /[abcd/.
2291    20. PCRE was getting more memory than necessary for patterns with classes that
2292    contained both POSIX named classes and other characters, e.g. /[[:space:]abc/.
2294    21. Added some code, conditional on #ifdef VPCOMPAT, to make life easier for
2295    compiling PCRE for use with Virtual Pascal.
2297    22. Small fix to the Makefile to make it work properly if the build is done
2298    outside the source tree.
2300    23. Added a new extension: a condition to go with recursion. If a conditional
2301    subpattern starts with (?(R) the "true" branch is used if recursion has
2302    happened, whereas the "false" branch is used only at the top level.
2304    24. When there was a very long string of literal characters (over 255 bytes
2305    without UTF support, over 250 bytes with UTF support), the computation of how
2306    much memory was required could be incorrect, leading to segfaults or other
2307    strange effects.
2309    25. PCRE was incorrectly assuming anchoring (either to start of subject or to
2310    start of line for a non-DOTALL pattern) when a pattern started with (.*) and
2311    there was a subsequent back reference to those brackets. This meant that, for
2312    example, /(.*)\d+\1/ failed to match "abc123bc". Unfortunately, it isn't
2313    possible to check for precisely this case. All we can do is abandon the
2314    optimization if .* occurs inside capturing brackets when there are any back
2315    references whatsoever. (See below for a better fix that came later.)
2317    26. The handling of the optimization for finding the first character of a
2318    non-anchored pattern, and for finding a character that is required later in the
2319    match were failing in some cases. This didn't break the matching; it just
2320    failed to optimize when it could. The way this is done has been re-implemented.
2322    27. Fixed typo in error message for invalid (?R item (it said "(?p").
2324    28. Added a new feature that provides some of the functionality that Perl
2325    provides with (?{...}). The facility is termed a "callout". The way it is done
2326    in PCRE is for the caller to provide an optional function, by setting
2327    pcre_callout to its entry point. Like pcre_malloc and pcre_free, this is a
2328    global variable. By default it is unset, which disables all calling out. To get
2329    the function called, the regex must include (?C) at appropriate points. This
2330    is, in fact, equivalent to (?C0), and any number <= 255 may be given with (?C).
2331    This provides a means of identifying different callout points. When PCRE
2332    reaches such a point in the regex, if pcre_callout has been set, the external
2333    function is called. It is provided with data in a structure called
2334    pcre_callout_block, which is defined in pcre.h. If the function returns 0,
2335    matching continues; if it returns a non-zero value, the match at the current
2336    point fails. However, backtracking will occur if possible. [This was changed
2337    later and other features added - see item 49 below.]
2339    29. pcretest is upgraded to test the callout functionality. It provides a
2340    callout function that displays information. By default, it shows the start of
2341    the match and the current position in the text. There are some new data escapes
2342    to vary what happens:
2344        \C+         in addition, show current contents of captured substrings
2345        \C-         do not supply a callout function
2346        \C!n        return 1 when callout number n is reached
2347        \C!n!m      return 1 when callout number n is reached for the mth time
2349    30. If pcregrep was called with the -l option and just a single file name, it
2350    output "<stdin>" if a match was found, instead of the file name.
2352    31. Improve the efficiency of the POSIX API to PCRE. If the number of capturing
2353    slots is less than POSIX_MALLOC_THRESHOLD, use a block on the stack to pass to
2354    pcre_exec(). This saves a malloc/free per call. The default value of
2355    POSIX_MALLOC_THRESHOLD is 10; it can be changed by --with-posix-malloc-threshold
2356    when configuring.
2358    32. The default maximum size of a compiled pattern is 64K. There have been a
2359    few cases of people hitting this limit. The code now uses macros to handle the
2360    storing of links as offsets within the compiled pattern. It defaults to 2-byte
2361    links, but this can be changed to 3 or 4 bytes by --with-link-size when
2362    configuring. Tests 2 and 5 work only with 2-byte links because they output
2363    debugging information about compiled patterns.
2365    33. Internal code re-arrangements:
2367    (a) Moved the debugging function for printing out a compiled regex into
2368        its own source file (printint.c) and used #include to pull it into
2369        pcretest.c and, when DEBUG is defined, into pcre.c, instead of having two
2370        separate copies.
2372    (b) Defined the list of op-code names for debugging as a macro in
2373        internal.h so that it is next to the definition of the opcodes.
2375    (c) Defined a table of op-code lengths for simpler skipping along compiled
2376        code. This is again a macro in internal.h so that it is next to the
2377        definition of the opcodes.
2379    34. Added support for recursive calls to individual subpatterns, along the
2380    lines of Robin Houston's patch (but implemented somewhat differently).
2382    35. Further mods to the Makefile to help Win32. Also, added code to pcregrep to
2383    allow it to read and process whole directories in Win32. This code was
2384    contributed by Lionel Fourquaux; it has not been tested by me.
2386    36. Added support for named subpatterns. The Python syntax (?P<name>...) is
2387    used to name a group. Names consist of alphanumerics and underscores, and must
2388    be unique. Back references use the syntax (?P=name) and recursive calls use
2389    (?P>name) which is a PCRE extension to the Python extension. Groups still have
2390    numbers. The function pcre_fullinfo() can be used after compilation to extract
2391    a name/number map. There are three relevant calls:
2393      PCRE_INFO_NAMEENTRYSIZE        yields the size of each entry in the map
2394      PCRE_INFO_NAMECOUNT            yields the number of entries
2395      PCRE_INFO_NAMETABLE            yields a pointer to the map.
2397    The map is a vector of fixed-size entries. The size of each entry depends on
2398    the length of the longest name used. The first two bytes of each entry are the
2399    group number, most significant byte first. There follows the corresponding
2400    name, zero terminated. The names are in alphabetical order.
2402    37. Make the maximum literal string in the compiled code 250 for the non-UTF-8
2403    case instead of 255. Making it the same both with and without UTF-8 support
2404    means that the same test output works with both.
2406    38. There was a case of malloc(0) in the POSIX testing code in pcretest. Avoid
2407    calling malloc() with a zero argument.
2409    39. Change 25 above had to resort to a heavy-handed test for the .* anchoring
2410    optimization. I've improved things by keeping a bitmap of backreferences with
2411    numbers 1-31 so that if .* occurs inside capturing brackets that are not in
2412    fact referenced, the optimization can be applied. It is unlikely that a
2413    relevant occurrence of .* (i.e. one which might indicate anchoring or forcing
2414    the match to follow \n) will appear inside brackets with a number greater than
2415    31, but if it does, any back reference > 31 suppresses the optimization.
2417    40. Added a new compile-time option PCRE_NO_AUTO_CAPTURE. This has the effect
2418    of disabling numbered capturing parentheses. Any opening parenthesis that is
2419    not followed by ? behaves as if it were followed by ?: but named parentheses
2420    can still be used for capturing (and they will acquire numbers in the usual
2421    way).
2423    41. Redesigned the return codes from the match() function into yes/no/error so
2424    that errors can be passed back from deep inside the nested calls. A malloc
2425    failure while inside a recursive subpattern call now causes the
2426    PCRE_ERROR_NOMEMORY return instead of quietly going wrong.
2428    42. It is now possible to set a limit on the number of times the match()
2429    function is called in a call to pcre_exec(). This facility makes it possible to
2430    limit the amount of recursion and backtracking, though not in a directly
2431    obvious way, because the match() function is used in a number of different
2432    circumstances. The count starts from zero for each position in the subject
2433    string (for non-anchored patterns). The default limit is, for compatibility, a
2434    large number, namely 10 000 000. You can change this in two ways:
2436    (a) When configuring PCRE before making, you can use --with-match-limit=n
2437        to set a default value for the compiled library.
2439    (b) For each call to pcre_exec(), you can pass a pcre_extra block in which
2440        a different value is set. See 45 below.
2442    If the limit is exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT.
2444    43. Added a new function pcre_config(int, void *) to enable run-time extraction
2445    of things that can be changed at compile time. The first argument specifies
2446    what is wanted and the second points to where the information is to be placed.
2447    The current list of available information is:
2449      PCRE_CONFIG_UTF8
2451    The output is an integer that is set to one if UTF-8 support is available;
2452    otherwise it is set to zero.
2456    The output is an integer that it set to the value of the code that is used for
2457    newline. It is either LF (10) or CR (13).
2461    The output is an integer that contains the number of bytes used for internal
2462    linkage in compiled expressions. The value is 2, 3, or 4. See item 32 above.
2466    The output is an integer that contains the threshold above which the POSIX
2467    interface uses malloc() for output vectors. See item 31 above.
2471    The output is an unsigned integer that contains the default limit of the number
2472    of match() calls in a pcre_exec() execution. See 42 above.
2474    44. pcretest has been upgraded by the addition of the -C option. This causes it
2475    to extract all the available output from the new pcre_config() function, and to
2476    output it. The program then exits immediately.
2478    45. A need has arisen to pass over additional data with calls to pcre_exec() in
2479    order to support additional features. One way would have been to define
2480    pcre_exec2() (for example) with extra arguments, but this would not have been
2481    extensible, and would also have required all calls to the original function to
2482    be mapped to the new one. Instead, I have chosen to extend the mechanism that
2483    is used for passing in "extra" data from pcre_study().
2485    The pcre_extra structure is now exposed and defined in pcre.h. It currently
2486    contains the following fields:
2488      flags         a bitmap indicating which of the following fields are set
2489      study_data    opaque data from pcre_study()
2490      match_limit   a way of specifying a limit on match() calls for a specific
2491                      call to pcre_exec()
2492      callout_data  data for callouts (see 49 below)
2494    The flag bits are also defined in pcre.h, and are
2500    The pcre_study() function now returns one of these new pcre_extra blocks, with
2501    the actual study data pointed to by the study_data field, and the
2502    PCRE_EXTRA_STUDY_DATA flag set. This can be passed directly to pcre_exec() as
2503    before. That is, this change is entirely upwards-compatible and requires no
2504    change to existing code.
2506    If you want to pass in additional data to pcre_exec(), you can either place it
2507    in a pcre_extra block provided by pcre_study(), or create your own pcre_extra
2508    block.
2510    46. pcretest has been extended to test the PCRE_EXTRA_MATCH_LIMIT feature. If a
2511    data string contains the escape sequence \M, pcretest calls pcre_exec() several
2512    times with different match limits, until it finds the minimum value needed for
2513    pcre_exec() to complete. The value is then output. This can be instructive; for
2514    most simple matches the number is quite small, but for pathological cases it
2515    gets very large very quickly.
2517    47. There's a new option for pcre_fullinfo() called PCRE_INFO_STUDYSIZE. It
2518    returns the size of the data block pointed to by the study_data field in a
2519    pcre_extra block, that is, the value that was passed as the argument to
2520    pcre_malloc() when PCRE was getting memory in which to place the information
2521    created by pcre_study(). The fourth argument should point to a size_t variable.
2522    pcretest has been extended so that this information is shown after a successful
2523    pcre_study() call when information about the compiled regex is being displayed.
2525    48. Cosmetic change to Makefile: there's no need to have / after $(DESTDIR)
2526    because what follows is always an absolute path. (Later: it turns out that this
2527    is more than cosmetic for MinGW, because it doesn't like empty path
2528    components.)
2530    49. Some changes have been made to the callout feature (see 28 above):
2532    (i)  A callout function now has three choices for what it returns:
2534           0  =>  success, carry on matching
2535         > 0  =>  failure at this point, but backtrack if possible
2536         < 0  =>  serious error, return this value from pcre_exec()
2538         Negative values should normally be chosen from the set of PCRE_ERROR_xxx
2539         values. In particular, returning PCRE_ERROR_NOMATCH forces a standard
2540         "match failed" error. The error number PCRE_ERROR_CALLOUT is reserved for
2541         use by callout functions. It will never be used by PCRE itself.
2543    (ii) The pcre_extra structure (see 45 above) has a void * field called
2544         callout_data, with corresponding flag bit PCRE_EXTRA_CALLOUT_DATA. The
2545         pcre_callout_block structure has a field of the same name. The contents of
2546         the field passed in the pcre_extra structure are passed to the callout
2547         function in the corresponding field in the callout block. This makes it
2548         easier to use the same callout-containing regex from multiple threads. For
2549         testing, the pcretest program has a new data escape
2551           \C*n        pass the number n (may be negative) as callout_data
2553         If the callout function in pcretest receives a non-zero value as
2554         callout_data, it returns that value.
2556    50. Makefile wasn't handling CFLAGS properly when compiling dftables. Also,
2557    there were some redundant $(CFLAGS) in commands that are now specified as
2558    $(LINK), which already includes $(CFLAGS).
2560    51. Extensions to UTF-8 support are listed below. These all apply when (a) PCRE
2561    has been compiled with UTF-8 support *and* pcre_compile() has been compiled
2562    with the PCRE_UTF8 flag. Patterns that are compiled without that flag assume
2563    one-byte characters throughout. Note that case-insensitive matching applies
2564    only to characters whose values are less than 256. PCRE doesn't support the
2565    notion of cases for higher-valued characters.
2567    (i)   A character class whose characters are all within 0-255 is handled as
2568          a bit map, and the map is inverted for negative classes. Previously, a
2569          character > 255 always failed to match such a class; however it should
2570          match if the class was a negative one (e.g. [^ab]). This has been fixed.
2572    (ii)  A negated character class with a single character < 255 is coded as
2573          "not this character" (OP_NOT). This wasn't working properly when the test
2574          character was multibyte, either singly or repeated.
2576    (iii) Repeats of multibyte characters are now handled correctly in UTF-8
2577          mode, for example: \x{100}{2,3}.
2579    (iv)  The character escapes \b, \B, \d, \D, \s, \S, \w, and \W (either
2580          singly or repeated) now correctly test multibyte characters. However,
2581          PCRE doesn't recognize any characters with values greater than 255 as
2582          digits, spaces, or word characters. Such characters always match \D, \S,
2583          and \W, and never match \d, \s, or \w.
2585    (v)   Classes may now contain characters and character ranges with values
2586          greater than 255. For example: [ab\x{100}-\x{400}].
2588    (vi)  pcregrep now has a --utf-8 option (synonym -u) which makes it call
2589          PCRE in UTF-8 mode.
2591    52. The info request value PCRE_INFO_FIRSTCHAR has been renamed
2592    PCRE_INFO_FIRSTBYTE because it is a byte value. However, the old name is
2593    retained for backwards compatibility. (Note that LASTLITERAL is also a byte
2594    value.)
2596    53. The single man page has become too large. I have therefore split it up into
2597    a number of separate man pages. These also give rise to individual HTML pages;
2598    these are now put in a separate directory, and there is an index.html page that
2599    lists them all. Some hyperlinking between the pages has been installed.
2601    54. Added convenience functions for handling named capturing parentheses.
2603    55. Unknown escapes inside character classes (e.g. [\M]) and escapes that
2604    aren't interpreted therein (e.g. [\C]) are literals in Perl. This is now also
2605    true in PCRE, except when the PCRE_EXTENDED option is set, in which case they
2606    are faulted.
2608    56. Introduced HOST_CC and HOST_CFLAGS which can be set in the environment when
2609    calling configure. These values are used when compiling the dftables.c program
2610    which is run to generate the source of the default character tables. They
2611    default to the values of CC and CFLAGS. If you are cross-compiling PCRE,
2612    you will need to set these values.
2614    57. Updated the building process for Windows DLL, as provided by Fred Cox.
2617    Version 3.9 02-Jan-02
2618  ---------------------  ---------------------
2620  1. A bit of extraneous text had somehow crept into the pcregrep documentation.  1. A bit of extraneous text had somehow crept into the pcregrep documentation.

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