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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
4  Version 3.0 02-Jan-02  Version 6.2 01-Aug-05
5    ---------------------
7     1. There was no test for integer overflow of quantifier values. A construction
8        such as {1111111111111111} would give undefined results. What is worse, if
9        a minimum quantifier for a parenthesized subpattern overflowed and became
10        negative, the calculation of the memory size went wrong. This could have
11        led to memory overwriting.
13     2. Building PCRE using VPATH was broken. Hopefully it is now fixed.
15     3. Added "b" to the 2nd argument of fopen() in dftables.c, for non-Unix-like
16        operating environments where this matters.
18     4. Applied Giuseppe Maxia's patch to add additional features for controlling
19        PCRE options from within the C++ wrapper.
21     5. Named capturing subpatterns were not being correctly counted when a pattern
22        was compiled. This caused two problems: (a) If there were more than 100
23        such subpatterns, the calculation of the memory needed for the whole
24        compiled pattern went wrong, leading to an overflow error. (b) Numerical
25        back references of the form \12, where the number was greater than 9, were
26        not recognized as back references, even though there were sufficient
27        previous subpatterns.
29     6. Two minor patches to pcrecpp.cc in order to allow it to compile on older
30        versions of gcc, e.g. 2.95.4.
33    Version 6.1 21-Jun-05
34    ---------------------
36     1. There was one reference to the variable "posix" in pcretest.c that was not
37        surrounded by "#if !defined NOPOSIX".
39     2. Make it possible to compile pcretest without DFA support, UTF8 support, or
40        the cross-check on the old pcre_info() function, for the benefit of the
41        cut-down version of PCRE that is currently imported into Exim.
43     3. A (silly) pattern starting with (?i)(?-i) caused an internal space
44        allocation error. I've done the easy fix, which wastes 2 bytes for sensible
45        patterns that start (?i) but I don't think that matters. The use of (?i) is
46        just an example; this all applies to the other options as well.
48     4. Since libtool seems to echo the compile commands it is issuing, the output
49        from "make" can be reduced a bit by putting "@" in front of each libtool
50        compile command.
52     5. Patch from the folks at Google for configure.in to be a bit more thorough
53        in checking for a suitable C++ installation before trying to compile the
54        C++ stuff. This should fix a reported problem when a compiler was present,
55        but no suitable headers.
57     6. The man pages all had just "PCRE" as their title. I have changed them to
58        be the relevant file name. I have also arranged that these names are
59        retained in the file doc/pcre.txt, which is a concatenation in text format
60        of all the man pages except the little individual ones for each function.
62     7. The NON-UNIX-USE file had not been updated for the different set of source
63        files that come with release 6. I also added a few comments about the C++
64        wrapper.
67    Version 6.0 07-Jun-05
68    ---------------------
70     1. Some minor internal re-organization to help with my DFA experiments.
72     2. Some missing #ifdef SUPPORT_UCP conditionals in pcretest and printint that
73        didn't matter for the library itself when fully configured, but did matter
74        when compiling without UCP support, or within Exim, where the ucp files are
75        not imported.
77     3. Refactoring of the library code to split up the various functions into
78        different source modules. The addition of the new DFA matching code (see
79        below) to a single monolithic source would have made it really too
80        unwieldy, quite apart from causing all the code to be include in a
81        statically linked application, when only some functions are used. This is
82        relevant even without the DFA addition now that patterns can be compiled in
83        one application and matched in another.
85        The downside of splitting up is that there have to be some external
86        functions and data tables that are used internally in different modules of
87        the library but which are not part of the API. These have all had their
88        names changed to start with "_pcre_" so that they are unlikely to clash
89        with other external names.
91     4. Added an alternate matching function, pcre_dfa_exec(), which matches using
92        a different (DFA) algorithm. Although it is slower than the original
93        function, it does have some advantages for certain types of matching
94        problem.
96     5. Upgrades to pcretest in order to test the features of pcre_dfa_exec(),
97        including restarting after a partial match.
99     6. A patch for pcregrep that defines INVALID_FILE_ATTRIBUTES if it is not
100        defined when compiling for Windows was sent to me. I have put it into the
101        code, though I have no means of testing or verifying it.
103     7. Added the pcre_refcount() auxiliary function.
105     8. Added the PCRE_FIRSTLINE option. This constrains an unanchored pattern to
106        match before or at the first newline in the subject string. In pcretest,
107        the /f option on a pattern can be used to set this.
109     9. A repeated \w when used in UTF-8 mode with characters greater than 256
110        would behave wrongly. This has been present in PCRE since release 4.0.
112    10. A number of changes to the pcregrep command:
114        (a) Refactored how -x works; insert ^(...)$ instead of setting
115            PCRE_ANCHORED and checking the length, in preparation for adding
116            something similar for -w.
118        (b) Added the -w (match as a word) option.
120        (c) Refactored the way lines are read and buffered so as to have more
121            than one at a time available.
123        (d) Implemented a pcregrep test script.
125        (e) Added the -M (multiline match) option. This allows patterns to match
126            over several lines of the subject. The buffering ensures that at least
127            8K, or the rest of the document (whichever is the shorter) is available
128            for matching (and similarly the previous 8K for lookbehind assertions).
130        (f) Changed the --help output so that it now says
132              -w, --word-regex(p)
134            instead of two lines, one with "regex" and the other with "regexp"
135            because that confused at least one person since the short forms are the
136            same. (This required a bit of code, as the output is generated
137            automatically from a table. It wasn't just a text change.)
139        (g) -- can be used to terminate pcregrep options if the next thing isn't an
140            option but starts with a hyphen. Could be a pattern or a path name
141            starting with a hyphen, for instance.
143        (h) "-" can be given as a file name to represent stdin.
145        (i) When file names are being printed, "(standard input)" is used for
146            the standard input, for compatibility with GNU grep. Previously
147            "<stdin>" was used.
149        (j) The option --label=xxx can be used to supply a name to be used for
150            stdin when file names are being printed. There is no short form.
152        (k) Re-factored the options decoding logic because we are going to add
153            two more options that take data. Such options can now be given in four
154            different ways, e.g. "-fname", "-f name", "--file=name", "--file name".
156        (l) Added the -A, -B, and -C options for requesting that lines of context
157            around matches be printed.
159        (m) Added the -L option to print the names of files that do not contain
160            any matching lines, that is, the complement of -l.
162        (n) The return code is 2 if any file cannot be opened, but pcregrep does
163            continue to scan other files.
165        (o) The -s option was incorrectly implemented. For compatibility with other
166            greps, it now suppresses the error message for a non-existent or non-
167            accessible file (but not the return code). There is a new option called
168            -q that suppresses the output of matching lines, which was what -s was
169            previously doing.
171        (p) Added --include and --exclude options to specify files for inclusion
172            and exclusion when recursing.
174    11. The Makefile was not using the Autoconf-supported LDFLAGS macro properly.
175        Hopefully, it now does.
177    12. Missing cast in pcre_study().
179    13. Added an "uninstall" target to the makefile.
181    14. Replaced "extern" in the function prototypes in Makefile.in with
182        "PCRE_DATA_SCOPE", which defaults to 'extern' or 'extern "C"' in the Unix
183        world, but is set differently for Windows.
185    15. Added a second compiling function called pcre_compile2(). The only
186        difference is that it has an extra argument, which is a pointer to an
187        integer error code. When there is a compile-time failure, this is set
188        non-zero, in addition to the error test pointer being set to point to an
189        error message. The new argument may be NULL if no error number is required
190        (but then you may as well call pcre_compile(), which is now just a
191        wrapper). This facility is provided because some applications need a
192        numeric error indication, but it has also enabled me to tidy up the way
193        compile-time errors are handled in the POSIX wrapper.
195    16. Added VPATH=.libs to the makefile; this should help when building with one
196        prefix path and installing with another. (Or so I'm told by someone who
197        knows more about this stuff than I do.)
199    17. Added a new option, REG_DOTALL, to the POSIX function regcomp(). This
200        passes PCRE_DOTALL to the pcre_compile() function, making the "." character
201        match everything, including newlines. This is not POSIX-compatible, but
202        somebody wanted the feature. From pcretest it can be activated by using
203        both the P and the s flags.
205    18. AC_PROG_LIBTOOL appeared twice in Makefile.in. Removed one.
207    19. libpcre.pc was being incorrectly installed as executable.
209    20. A couple of places in pcretest check for end-of-line by looking for '\n';
210        it now also looks for '\r' so that it will work unmodified on Windows.
212    21. Added Google's contributed C++ wrapper to the distribution.
214    22. Added some untidy missing memory free() calls in pcretest, to keep
215        Electric Fence happy when testing.
219    Version 5.0 13-Sep-04
220    ---------------------
222     1. Internal change: literal characters are no longer packed up into items
223        containing multiple characters in a single byte-string. Each character
224        is now matched using a separate opcode. However, there may be more than one
225        byte in the character in UTF-8 mode.
227     2. The pcre_callout_block structure has two new fields: pattern_position and
228        next_item_length. These contain the offset in the pattern to the next match
229        item, and its length, respectively.
231     3. The PCRE_AUTO_CALLOUT option for pcre_compile() requests the automatic
232        insertion of callouts before each pattern item. Added the /C option to
233        pcretest to make use of this.
235     4. On the advice of a Windows user, the lines
237          #if defined(_WIN32) || defined(WIN32)
238          _setmode( _fileno( stdout ), 0x8000 );
239          #endif  /* defined(_WIN32) || defined(WIN32) */
241        have been added to the source of pcretest. This apparently does useful
242        magic in relation to line terminators.
244     5. Changed "r" and "w" in the calls to fopen() in pcretest to "rb" and "wb"
245        for the benefit of those environments where the "b" makes a difference.
247     6. The icc compiler has the same options as gcc, but "configure" doesn't seem
248        to know about it. I have put a hack into configure.in that adds in code
249        to set GCC=yes if CC=icc. This seems to end up at a point in the
250        generated configure script that is early enough to affect the setting of
251        compiler options, which is what is needed, but I have no means of testing
252        whether it really works. (The user who reported this had patched the
253        generated configure script, which of course I cannot do.)
255        LATER: After change 22 below (new libtool files), the configure script
256        seems to know about icc (and also ecc). Therefore, I have commented out
257        this hack in configure.in.
259     7. Added support for pkg-config (2 patches were sent in).
261     8. Negated POSIX character classes that used a combination of internal tables
262        were completely broken. These were [[:^alpha:]], [[:^alnum:]], and
263        [[:^ascii]]. Typically, they would match almost any characters. The other
264        POSIX classes were not broken in this way.
266     9. Matching the pattern "\b.*?" against "ab cd", starting at offset 1, failed
267        to find the match, as PCRE was deluded into thinking that the match had to
268        start at the start point or following a newline. The same bug applied to
269        patterns with negative forward assertions or any backward assertions
270        preceding ".*" at the start, unless the pattern required a fixed first
271        character. This was a failing pattern: "(?!.bcd).*". The bug is now fixed.
273    10. In UTF-8 mode, when moving forwards in the subject after a failed match
274        starting at the last subject character, bytes beyond the end of the subject
275        string were read.
277    11. Renamed the variable "class" as "classbits" to make life easier for C++
278        users. (Previously there was a macro definition, but it apparently wasn't
279        enough.)
281    12. Added the new field "tables" to the extra data so that tables can be passed
282        in at exec time, or the internal tables can be re-selected. This allows
283        a compiled regex to be saved and re-used at a later time by a different
284        program that might have everything at different addresses.
286    13. Modified the pcre-config script so that, when run on Solaris, it shows a
287        -R library as well as a -L library.
289    14. The debugging options of pcretest (-d on the command line or D on a
290        pattern) showed incorrect output for anything following an extended class
291        that contained multibyte characters and which was followed by a quantifier.
293    15. Added optional support for general category Unicode character properties
294        via the \p, \P, and \X escapes. Unicode property support implies UTF-8
295        support. It adds about 90K to the size of the library. The meanings of the
296        inbuilt class escapes such as \d and \s have NOT been changed.
298    16. Updated pcredemo.c to include calls to free() to release the memory for the
299        compiled pattern.
301    17. The generated file chartables.c was being created in the source directory
302        instead of in the building directory. This caused the build to fail if the
303        source directory was different from the building directory, and was
304        read-only.
306    18. Added some sample Win commands from Mark Tetrode into the NON-UNIX-USE
307        file. No doubt somebody will tell me if they don't make sense... Also added
308        Dan Mooney's comments about building on OpenVMS.
310    19. Added support for partial matching via the PCRE_PARTIAL option for
311        pcre_exec() and the \P data escape in pcretest.
313    20. Extended pcretest with 3 new pattern features:
315        (i)   A pattern option of the form ">rest-of-line" causes pcretest to
316              write the compiled pattern to the file whose name is "rest-of-line".
317              This is a straight binary dump of the data, with the saved pointer to
318              the character tables forced to be NULL. The study data, if any, is
319              written too. After writing, pcretest reads a new pattern.
321        (ii)  If, instead of a pattern, "<rest-of-line" is given, pcretest reads a
322              compiled pattern from the given file. There must not be any
323              occurrences of "<" in the file name (pretty unlikely); if there are,
324              pcretest will instead treat the initial "<" as a pattern delimiter.
325              After reading in the pattern, pcretest goes on to read data lines as
326              usual.
328        (iii) The F pattern option causes pcretest to flip the bytes in the 32-bit
329              and 16-bit fields in a compiled pattern, to simulate a pattern that
330              was compiled on a host of opposite endianness.
332    21. The pcre-exec() function can now cope with patterns that were compiled on
333        hosts of opposite endianness, with this restriction:
335          As for any compiled expression that is saved and used later, the tables
336          pointer field cannot be preserved; the extra_data field in the arguments
337          to pcre_exec() should be used to pass in a tables address if a value
338          other than the default internal tables were used at compile time.
340    22. Calling pcre_exec() with a negative value of the "ovecsize" parameter is
341        now diagnosed as an error. Previously, most of the time, a negative number
342        would have been treated as zero, but if in addition "ovector" was passed as
343        NULL, a crash could occur.
345    23. Updated the files ltmain.sh, config.sub, config.guess, and aclocal.m4 with
346        new versions from the libtool 1.5 distribution (the last one is a copy of
347        a file called libtool.m4). This seems to have fixed the need to patch
348        "configure" to support Darwin 1.3 (which I used to do). However, I still
349        had to patch ltmain.sh to ensure that ${SED} is set (it isn't on my
350        workstation).
352    24. Changed the PCRE licence to be the more standard "BSD" licence.
355    Version 4.5 01-Dec-03
356    ---------------------
358     1. There has been some re-arrangement of the code for the match() function so
359        that it can be compiled in a version that does not call itself recursively.
360        Instead, it keeps those local variables that need separate instances for
361        each "recursion" in a frame on the heap, and gets/frees frames whenever it
362        needs to "recurse". Keeping track of where control must go is done by means
363        of setjmp/longjmp. The whole thing is implemented by a set of macros that
364        hide most of the details from the main code, and operates only if
365        NO_RECURSE is defined while compiling pcre.c. If PCRE is built using the
366        "configure" mechanism, "--disable-stack-for-recursion" turns on this way of
367        operating.
369        To make it easier for callers to provide specially tailored get/free
370        functions for this usage, two new functions, pcre_stack_malloc, and
371        pcre_stack_free, are used. They are always called in strict stacking order,
372        and the size of block requested is always the same.
374        The PCRE_CONFIG_STACKRECURSE info parameter can be used to find out whether
375        PCRE has been compiled to use the stack or the heap for recursion. The
376        -C option of pcretest uses this to show which version is compiled.
378        A new data escape \S, is added to pcretest; it causes the amounts of store
379        obtained and freed by both kinds of malloc/free at match time to be added
380        to the output.
382     2. Changed the locale test to use "fr_FR" instead of "fr" because that's
383        what's available on my current Linux desktop machine.
385     3. When matching a UTF-8 string, the test for a valid string at the start has
386        been extended. If start_offset is not zero, PCRE now checks that it points
387        to a byte that is the start of a UTF-8 character. If not, it returns
388        PCRE_ERROR_BADUTF8_OFFSET (-11). Note: the whole string is still checked;
389        this is necessary because there may be backward assertions in the pattern.
390        When matching the same subject several times, it may save resources to use
391        PCRE_NO_UTF8_CHECK on all but the first call if the string is long.
393     4. The code for checking the validity of UTF-8 strings has been tightened so
394        that it rejects (a) strings containing 0xfe or 0xff bytes and (b) strings
395        containing "overlong sequences".
397     5. Fixed a bug (appearing twice) that I could not find any way of exploiting!
398        I had written "if ((digitab[*p++] && chtab_digit) == 0)" where the "&&"
399        should have been "&", but it just so happened that all the cases this let
400        through by mistake were picked up later in the function.
402     6. I had used a variable called "isblank" - this is a C99 function, causing
403        some compilers to warn. To avoid this, I renamed it (as "blankclass").
405     7. Cosmetic: (a) only output another newline at the end of pcretest if it is
406        prompting; (b) run "./pcretest /dev/null" at the start of the test script
407        so the version is shown; (c) stop "make test" echoing "./RunTest".
409     8. Added patches from David Burgess to enable PCRE to run on EBCDIC systems.
411     9. The prototype for memmove() for systems that don't have it was using
412        size_t, but the inclusion of the header that defines size_t was later. I've
413        moved the #includes for the C headers earlier to avoid this.
415    10. Added some adjustments to the code to make it easier to compiler on certain
416        special systems:
418          (a) Some "const" qualifiers were missing.
419          (b) Added the macro EXPORT before all exported functions; by default this
420              is defined to be empty.
421          (c) Changed the dftables auxiliary program (that builds chartables.c) so
422              that it reads its output file name as an argument instead of writing
423              to the standard output and assuming this can be redirected.
425    11. In UTF-8 mode, if a recursive reference (e.g. (?1)) followed a character
426        class containing characters with values greater than 255, PCRE compilation
427        went into a loop.
429    12. A recursive reference to a subpattern that was within another subpattern
430        that had a minimum quantifier of zero caused PCRE to crash. For example,
431        (x(y(?2))z)? provoked this bug with a subject that got as far as the
432        recursion. If the recursively-called subpattern itself had a zero repeat,
433        that was OK.
435    13. In pcretest, the buffer for reading a data line was set at 30K, but the
436        buffer into which it was copied (for escape processing) was still set at
437        1024, so long lines caused crashes.
439    14. A pattern such as /[ab]{1,3}+/ failed to compile, giving the error
440        "internal error: code overflow...". This applied to any character class
441        that was followed by a possessive quantifier.
443    15. Modified the Makefile to add libpcre.la as a prerequisite for
444        libpcreposix.la because I was told this is needed for a parallel build to
445        work.
447    16. If a pattern that contained .* following optional items at the start was
448        studied, the wrong optimizing data was generated, leading to matching
449        errors. For example, studying /[ab]*.*c/ concluded, erroneously, that any
450        matching string must start with a or b or c. The correct conclusion for
451        this pattern is that a match can start with any character.
454    Version 4.4 13-Aug-03
455    ---------------------
457     1. In UTF-8 mode, a character class containing characters with values between
458        127 and 255 was not handled correctly if the compiled pattern was studied.
459        In fixing this, I have also improved the studying algorithm for such
460        classes (slightly).
462     2. Three internal functions had redundant arguments passed to them. Removal
463        might give a very teeny performance improvement.
465     3. Documentation bug: the value of the capture_top field in a callout is *one
466        more than* the number of the hightest numbered captured substring.
468     4. The Makefile linked pcretest and pcregrep with -lpcre, which could result
469        in incorrectly linking with a previously installed version. They now link
470        explicitly with libpcre.la.
472     5. configure.in no longer needs to recognize Cygwin specially.
474     6. A problem in pcre.in for Windows platforms is fixed.
476     7. If a pattern was successfully studied, and the -d (or /D) flag was given to
477        pcretest, it used to include the size of the study block as part of its
478        output. Unfortunately, the structure contains a field that has a different
479        size on different hardware architectures. This meant that the tests that
480        showed this size failed. As the block is currently always of a fixed size,
481        this information isn't actually particularly useful in pcretest output, so
482        I have just removed it.
484     8. Three pre-processor statements accidentally did not start in column 1.
485        Sadly, there are *still* compilers around that complain, even though
486        standard C has not required this for well over a decade. Sigh.
488     9. In pcretest, the code for checking callouts passed small integers in the
489        callout_data field, which is a void * field. However, some picky compilers
490        complained about the casts involved for this on 64-bit systems. Now
491        pcretest passes the address of the small integer instead, which should get
492        rid of the warnings.
494    10. By default, when in UTF-8 mode, PCRE now checks for valid UTF-8 strings at
495        both compile and run time, and gives an error if an invalid UTF-8 sequence
496        is found. There is a option for disabling this check in cases where the
497        string is known to be correct and/or the maximum performance is wanted.
499    11. In response to a bug report, I changed one line in Makefile.in from
501            -Wl,--out-implib,.libs/lib@WIN_PREFIX@pcreposix.dll.a \
502        to
503            -Wl,--out-implib,.libs/@WIN_PREFIX@libpcreposix.dll.a \
505        to look similar to other lines, but I have no way of telling whether this
506        is the right thing to do, as I do not use Windows. No doubt I'll get told
507        if it's wrong...
510    Version 4.3 21-May-03
511    ---------------------
513    1. Two instances of @WIN_PREFIX@ omitted from the Windows targets in the
514       Makefile.
516    2. Some refactoring to improve the quality of the code:
518       (i)   The utf8_table... variables are now declared "const".
520       (ii)  The code for \cx, which used the "case flipping" table to upper case
521             lower case letters, now just substracts 32. This is ASCII-specific,
522             but the whole concept of \cx is ASCII-specific, so it seems
523             reasonable.
525       (iii) PCRE was using its character types table to recognize decimal and
526             hexadecimal digits in the pattern. This is silly, because it handles
527             only 0-9, a-f, and A-F, but the character types table is locale-
528             specific, which means strange things might happen. A private
529             table is now used for this - though it costs 256 bytes, a table is
530             much faster than multiple explicit tests. Of course, the standard
531             character types table is still used for matching digits in subject
532             strings against \d.
534       (iv)  Strictly, the identifier ESC_t is reserved by POSIX (all identifiers
535             ending in _t are). So I've renamed it as ESC_tee.
537    3. The first argument for regexec() in the POSIX wrapper should have been
538       defined as "const".
540    4. Changed pcretest to use malloc() for its buffers so that they can be
541       Electric Fenced for debugging.
543    5. There were several places in the code where, in UTF-8 mode, PCRE would try
544       to read one or more bytes before the start of the subject string. Often this
545       had no effect on PCRE's behaviour, but in some circumstances it could
546       provoke a segmentation fault.
548    6. A lookbehind at the start of a pattern in UTF-8 mode could also cause PCRE
549       to try to read one or more bytes before the start of the subject string.
551    7. A lookbehind in a pattern matched in non-UTF-8 mode on a PCRE compiled with
552       UTF-8 support could misbehave in various ways if the subject string
553       contained bytes with the 0x80 bit set and the 0x40 bit unset in a lookbehind
554       area. (PCRE was not checking for the UTF-8 mode flag, and trying to move
555       back over UTF-8 characters.)
558    Version 4.2 14-Apr-03
559    ---------------------
561    1. Typo "#if SUPPORT_UTF8" instead of "#ifdef SUPPORT_UTF8" fixed.
563    2. Changes to the building process, supplied by Ronald Landheer-Cieslak
564         [ON_WINDOWS]: new variable, "#" on non-Windows platforms
565         [NOT_ON_WINDOWS]: new variable, "#" on Windows platforms
566         [WIN_PREFIX]: new variable, "cyg" for Cygwin
567         * Makefile.in: use autoconf substitution for OBJEXT, EXEEXT, BUILD_OBJEXT
568           and BUILD_EXEEXT
569         Note: automatic setting of the BUILD variables is not yet working
570         set CPPFLAGS and BUILD_CPPFLAGS (but don't use yet) - should be used at
571           compile-time but not at link-time
572         [LINK]: use for linking executables only
573         make different versions for Windows and non-Windows
574         [LINKLIB]: new variable, copy of UNIX-style LINK, used for linking
575           libraries
576         [LINK_FOR_BUILD]: new variable
577         [OBJEXT]: use throughout
578         [EXEEXT]: use throughout
579         <winshared>: new target
580         <wininstall>: new target
581         <dftables.o>: use native compiler
582         <dftables>: use native linker
583         <install>: handle Windows platform correctly
584         <clean>: ditto
585         <check>: ditto
586         copy DLL to top builddir before testing
588       As part of these changes, -no-undefined was removed again. This was reported
589       to give trouble on HP-UX 11.0, so getting rid of it seems like a good idea
590       in any case.
592    3. Some tidies to get rid of compiler warnings:
594       . In the match_data structure, match_limit was an unsigned long int, whereas
595         match_call_count was an int. I've made them both unsigned long ints.
597       . In pcretest the fact that a const uschar * doesn't automatically cast to
598         a void * provoked a warning.
600       . Turning on some more compiler warnings threw up some "shadow" variables
601         and a few more missing casts.
603    4. If PCRE was complied with UTF-8 support, but called without the PCRE_UTF8
604       option, a class that contained a single character with a value between 128
605       and 255 (e.g. /[\xFF]/) caused PCRE to crash.
607    5. If PCRE was compiled with UTF-8 support, but called without the PCRE_UTF8
608       option, a class that contained several characters, but with at least one
609       whose value was between 128 and 255 caused PCRE to crash.
612    Version 4.1 12-Mar-03
613    ---------------------
615    1. Compiling with gcc -pedantic found a couple of places where casts were
616    needed, and a string in dftables.c that was longer than standard compilers are
617    required to support.
619    2. Compiling with Sun's compiler found a few more places where the code could
620    be tidied up in order to avoid warnings.
622    3. The variables for cross-compiling were called HOST_CC and HOST_CFLAGS; the
623    first of these names is deprecated in the latest Autoconf in favour of the name
624    CC_FOR_BUILD, because "host" is typically used to mean the system on which the
625    compiled code will be run. I can't find a reference for HOST_CFLAGS, but by
626    analogy I have changed it to CFLAGS_FOR_BUILD.
628    4. Added -no-undefined to the linking command in the Makefile, because this is
629    apparently helpful for Windows. To make it work, also added "-L. -lpcre" to the
630    linking step for the pcreposix library.
632    5. PCRE was failing to diagnose the case of two named groups with the same
633    name.
635    6. A problem with one of PCRE's optimizations was discovered. PCRE remembers a
636    literal character that is needed in the subject for a match, and scans along to
637    ensure that it is present before embarking on the full matching process. This
638    saves time in cases of nested unlimited repeats that are never going to match.
639    Problem: the scan can take a lot of time if the subject is very long (e.g.
640    megabytes), thus penalizing straightforward matches. It is now done only if the
641    amount of subject to be scanned is less than 1000 bytes.
643    7. A lesser problem with the same optimization is that it was recording the
644    first character of an anchored pattern as "needed", thus provoking a search
645    right along the subject, even when the first match of the pattern was going to
646    fail. The "needed" character is now not set for anchored patterns, unless it
647    follows something in the pattern that is of non-fixed length. Thus, it still
648    fulfils its original purpose of finding quick non-matches in cases of nested
649    unlimited repeats, but isn't used for simple anchored patterns such as /^abc/.
652    Version 4.0 17-Feb-03
653    ---------------------
655    1. If a comment in an extended regex that started immediately after a meta-item
656    extended to the end of string, PCRE compiled incorrect data. This could lead to
657    all kinds of weird effects. Example: /#/ was bad; /()#/ was bad; /a#/ was not.
659    2. Moved to autoconf 2.53 and libtool 1.4.2.
661    3. Perl 5.8 no longer needs "use utf8" for doing UTF-8 things. Consequently,
662    the special perltest8 script is no longer needed - all the tests can be run
663    from a single perltest script.
665    4. From 5.004, Perl has not included the VT character (0x0b) in the set defined
666    by \s. It has now been removed in PCRE. This means it isn't recognized as
667    whitespace in /x regexes too, which is the same as Perl. Note that the POSIX
668    class [:space:] *does* include VT, thereby creating a mess.
670    5. Added the class [:blank:] (a GNU extension from Perl 5.8) to match only
671    space and tab.
673    6. Perl 5.005 was a long time ago. It's time to amalgamate the tests that use
674    its new features into the main test script, reducing the number of scripts.
676    7. Perl 5.8 has changed the meaning of patterns like /a(?i)b/. Earlier versions
677    were backward compatible, and made the (?i) apply to the whole pattern, as if
678    /i were given. Now it behaves more logically, and applies the option setting
679    only to what follows. PCRE has been changed to follow suit. However, if it
680    finds options settings right at the start of the pattern, it extracts them into
681    the global options, as before. Thus, they show up in the info data.
683    8. Added support for the \Q...\E escape sequence. Characters in between are
684    treated as literals. This is slightly different from Perl in that $ and @ are
685    also handled as literals inside the quotes. In Perl, they will cause variable
686    interpolation. Note the following examples:
688        Pattern            PCRE matches      Perl matches
690        \Qabc$xyz\E        abc$xyz           abc followed by the contents of $xyz
691        \Qabc\$xyz\E       abc\$xyz          abc\$xyz
692        \Qabc\E\$\Qxyz\E   abc$xyz           abc$xyz
694    For compatibility with Perl, \Q...\E sequences are recognized inside character
695    classes as well as outside them.
697    9. Re-organized 3 code statements in pcretest to avoid "overflow in
698    floating-point constant arithmetic" warnings from a Microsoft compiler. Added a
699    (size_t) cast to one statement in pcretest and one in pcreposix to avoid
700    signed/unsigned warnings.
702    10. SunOS4 doesn't have strtoul(). This was used only for unpicking the -o
703    option for pcretest, so I've replaced it by a simple function that does just
704    that job.
706    11. pcregrep was ending with code 0 instead of 2 for the commands "pcregrep" or
707    "pcregrep -".
709    12. Added "possessive quantifiers" ?+, *+, ++, and {,}+ which come from Sun's
710    Java package. This provides some syntactic sugar for simple cases of what my
711    documentation calls "once-only subpatterns". A pattern such as x*+ is the same
712    as (?>x*). In other words, if what is inside (?>...) is just a single repeated
713    item, you can use this simplified notation. Note that only makes sense with
714    greedy quantifiers. Consequently, the use of the possessive quantifier forces
715    greediness, whatever the setting of the PCRE_UNGREEDY option.
717    13. A change of greediness default within a pattern was not taking effect at
718    the current level for patterns like /(b+(?U)a+)/. It did apply to parenthesized
719    subpatterns that followed. Patterns like /b+(?U)a+/ worked because the option
720    was abstracted outside.
722    14. PCRE now supports the \G assertion. It is true when the current matching
723    position is at the start point of the match. This differs from \A when the
724    starting offset is non-zero. Used with the /g option of pcretest (or similar
725    code), it works in the same way as it does for Perl's /g option. If all
726    alternatives of a regex begin with \G, the expression is anchored to the start
727    match position, and the "anchored" flag is set in the compiled expression.
729    15. Some bugs concerning the handling of certain option changes within patterns
730    have been fixed. These applied to options other than (?ims). For example,
731    "a(?x: b c )d" did not match "XabcdY" but did match "Xa b c dY". It should have
732    been the other way round. Some of this was related to change 7 above.
734    16. PCRE now gives errors for /[.x.]/ and /[=x=]/ as unsupported POSIX
735    features, as Perl does. Previously, PCRE gave the warnings only for /[[.x.]]/
736    and /[[=x=]]/. PCRE now also gives an error for /[:name:]/ because it supports
737    POSIX classes only within a class (e.g. /[[:alpha:]]/).
739    17. Added support for Perl's \C escape. This matches one byte, even in UTF8
740    mode. Unlike ".", it always matches newline, whatever the setting of
741    PCRE_DOTALL. However, PCRE does not permit \C to appear in lookbehind
742    assertions. Perl allows it, but it doesn't (in general) work because it can't
743    calculate the length of the lookbehind. At least, that's the case for Perl
744    5.8.0 - I've been told they are going to document that it doesn't work in
745    future.
747    18. Added an error diagnosis for escapes that PCRE does not support: these are
748    \L, \l, \N, \P, \p, \U, \u, and \X.
750    19. Although correctly diagnosing a missing ']' in a character class, PCRE was
751    reading past the end of the pattern in cases such as /[abcd/.
753    20. PCRE was getting more memory than necessary for patterns with classes that
754    contained both POSIX named classes and other characters, e.g. /[[:space:]abc/.
756    21. Added some code, conditional on #ifdef VPCOMPAT, to make life easier for
757    compiling PCRE for use with Virtual Pascal.
759    22. Small fix to the Makefile to make it work properly if the build is done
760    outside the source tree.
762    23. Added a new extension: a condition to go with recursion. If a conditional
763    subpattern starts with (?(R) the "true" branch is used if recursion has
764    happened, whereas the "false" branch is used only at the top level.
766    24. When there was a very long string of literal characters (over 255 bytes
767    without UTF support, over 250 bytes with UTF support), the computation of how
768    much memory was required could be incorrect, leading to segfaults or other
769    strange effects.
771    25. PCRE was incorrectly assuming anchoring (either to start of subject or to
772    start of line for a non-DOTALL pattern) when a pattern started with (.*) and
773    there was a subsequent back reference to those brackets. This meant that, for
774    example, /(.*)\d+\1/ failed to match "abc123bc". Unfortunately, it isn't
775    possible to check for precisely this case. All we can do is abandon the
776    optimization if .* occurs inside capturing brackets when there are any back
777    references whatsoever. (See below for a better fix that came later.)
779    26. The handling of the optimization for finding the first character of a
780    non-anchored pattern, and for finding a character that is required later in the
781    match were failing in some cases. This didn't break the matching; it just
782    failed to optimize when it could. The way this is done has been re-implemented.
784    27. Fixed typo in error message for invalid (?R item (it said "(?p").
786    28. Added a new feature that provides some of the functionality that Perl
787    provides with (?{...}). The facility is termed a "callout". The way it is done
788    in PCRE is for the caller to provide an optional function, by setting
789    pcre_callout to its entry point. Like pcre_malloc and pcre_free, this is a
790    global variable. By default it is unset, which disables all calling out. To get
791    the function called, the regex must include (?C) at appropriate points. This
792    is, in fact, equivalent to (?C0), and any number <= 255 may be given with (?C).
793    This provides a means of identifying different callout points. When PCRE
794    reaches such a point in the regex, if pcre_callout has been set, the external
795    function is called. It is provided with data in a structure called
796    pcre_callout_block, which is defined in pcre.h. If the function returns 0,
797    matching continues; if it returns a non-zero value, the match at the current
798    point fails. However, backtracking will occur if possible. [This was changed
799    later and other features added - see item 49 below.]
801    29. pcretest is upgraded to test the callout functionality. It provides a
802    callout function that displays information. By default, it shows the start of
803    the match and the current position in the text. There are some new data escapes
804    to vary what happens:
806        \C+         in addition, show current contents of captured substrings
807        \C-         do not supply a callout function
808        \C!n        return 1 when callout number n is reached
809        \C!n!m      return 1 when callout number n is reached for the mth time
811    30. If pcregrep was called with the -l option and just a single file name, it
812    output "<stdin>" if a match was found, instead of the file name.
814    31. Improve the efficiency of the POSIX API to PCRE. If the number of capturing
815    slots is less than POSIX_MALLOC_THRESHOLD, use a block on the stack to pass to
816    pcre_exec(). This saves a malloc/free per call. The default value of
817    POSIX_MALLOC_THRESHOLD is 10; it can be changed by --with-posix-malloc-threshold
818    when configuring.
820    32. The default maximum size of a compiled pattern is 64K. There have been a
821    few cases of people hitting this limit. The code now uses macros to handle the
822    storing of links as offsets within the compiled pattern. It defaults to 2-byte
823    links, but this can be changed to 3 or 4 bytes by --with-link-size when
824    configuring. Tests 2 and 5 work only with 2-byte links because they output
825    debugging information about compiled patterns.
827    33. Internal code re-arrangements:
829    (a) Moved the debugging function for printing out a compiled regex into
830        its own source file (printint.c) and used #include to pull it into
831        pcretest.c and, when DEBUG is defined, into pcre.c, instead of having two
832        separate copies.
834    (b) Defined the list of op-code names for debugging as a macro in
835        internal.h so that it is next to the definition of the opcodes.
837    (c) Defined a table of op-code lengths for simpler skipping along compiled
838        code. This is again a macro in internal.h so that it is next to the
839        definition of the opcodes.
841    34. Added support for recursive calls to individual subpatterns, along the
842    lines of Robin Houston's patch (but implemented somewhat differently).
844    35. Further mods to the Makefile to help Win32. Also, added code to pcregrep to
845    allow it to read and process whole directories in Win32. This code was
846    contributed by Lionel Fourquaux; it has not been tested by me.
848    36. Added support for named subpatterns. The Python syntax (?P<name>...) is
849    used to name a group. Names consist of alphanumerics and underscores, and must
850    be unique. Back references use the syntax (?P=name) and recursive calls use
851    (?P>name) which is a PCRE extension to the Python extension. Groups still have
852    numbers. The function pcre_fullinfo() can be used after compilation to extract
853    a name/number map. There are three relevant calls:
855      PCRE_INFO_NAMEENTRYSIZE        yields the size of each entry in the map
856      PCRE_INFO_NAMECOUNT            yields the number of entries
857      PCRE_INFO_NAMETABLE            yields a pointer to the map.
859    The map is a vector of fixed-size entries. The size of each entry depends on
860    the length of the longest name used. The first two bytes of each entry are the
861    group number, most significant byte first. There follows the corresponding
862    name, zero terminated. The names are in alphabetical order.
864    37. Make the maximum literal string in the compiled code 250 for the non-UTF-8
865    case instead of 255. Making it the same both with and without UTF-8 support
866    means that the same test output works with both.
868    38. There was a case of malloc(0) in the POSIX testing code in pcretest. Avoid
869    calling malloc() with a zero argument.
871    39. Change 25 above had to resort to a heavy-handed test for the .* anchoring
872    optimization. I've improved things by keeping a bitmap of backreferences with
873    numbers 1-31 so that if .* occurs inside capturing brackets that are not in
874    fact referenced, the optimization can be applied. It is unlikely that a
875    relevant occurrence of .* (i.e. one which might indicate anchoring or forcing
876    the match to follow \n) will appear inside brackets with a number greater than
877    31, but if it does, any back reference > 31 suppresses the optimization.
879    40. Added a new compile-time option PCRE_NO_AUTO_CAPTURE. This has the effect
880    of disabling numbered capturing parentheses. Any opening parenthesis that is
881    not followed by ? behaves as if it were followed by ?: but named parentheses
882    can still be used for capturing (and they will acquire numbers in the usual
883    way).
885    41. Redesigned the return codes from the match() function into yes/no/error so
886    that errors can be passed back from deep inside the nested calls. A malloc
887    failure while inside a recursive subpattern call now causes the
888    PCRE_ERROR_NOMEMORY return instead of quietly going wrong.
890    42. It is now possible to set a limit on the number of times the match()
891    function is called in a call to pcre_exec(). This facility makes it possible to
892    limit the amount of recursion and backtracking, though not in a directly
893    obvious way, because the match() function is used in a number of different
894    circumstances. The count starts from zero for each position in the subject
895    string (for non-anchored patterns). The default limit is, for compatibility, a
896    large number, namely 10 000 000. You can change this in two ways:
898    (a) When configuring PCRE before making, you can use --with-match-limit=n
899        to set a default value for the compiled library.
901    (b) For each call to pcre_exec(), you can pass a pcre_extra block in which
902        a different value is set. See 45 below.
904    If the limit is exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT.
906    43. Added a new function pcre_config(int, void *) to enable run-time extraction
907    of things that can be changed at compile time. The first argument specifies
908    what is wanted and the second points to where the information is to be placed.
909    The current list of available information is:
913    The output is an integer that is set to one if UTF-8 support is available;
914    otherwise it is set to zero.
918    The output is an integer that it set to the value of the code that is used for
919    newline. It is either LF (10) or CR (13).
923    The output is an integer that contains the number of bytes used for internal
924    linkage in compiled expressions. The value is 2, 3, or 4. See item 32 above.
928    The output is an integer that contains the threshold above which the POSIX
929    interface uses malloc() for output vectors. See item 31 above.
933    The output is an unsigned integer that contains the default limit of the number
934    of match() calls in a pcre_exec() execution. See 42 above.
936    44. pcretest has been upgraded by the addition of the -C option. This causes it
937    to extract all the available output from the new pcre_config() function, and to
938    output it. The program then exits immediately.
940    45. A need has arisen to pass over additional data with calls to pcre_exec() in
941    order to support additional features. One way would have been to define
942    pcre_exec2() (for example) with extra arguments, but this would not have been
943    extensible, and would also have required all calls to the original function to
944    be mapped to the new one. Instead, I have chosen to extend the mechanism that
945    is used for passing in "extra" data from pcre_study().
947    The pcre_extra structure is now exposed and defined in pcre.h. It currently
948    contains the following fields:
950      flags         a bitmap indicating which of the following fields are set
951      study_data    opaque data from pcre_study()
952      match_limit   a way of specifying a limit on match() calls for a specific
953                      call to pcre_exec()
954      callout_data  data for callouts (see 49 below)
956    The flag bits are also defined in pcre.h, and are
962    The pcre_study() function now returns one of these new pcre_extra blocks, with
963    the actual study data pointed to by the study_data field, and the
964    PCRE_EXTRA_STUDY_DATA flag set. This can be passed directly to pcre_exec() as
965    before. That is, this change is entirely upwards-compatible and requires no
966    change to existing code.
968    If you want to pass in additional data to pcre_exec(), you can either place it
969    in a pcre_extra block provided by pcre_study(), or create your own pcre_extra
970    block.
972    46. pcretest has been extended to test the PCRE_EXTRA_MATCH_LIMIT feature. If a
973    data string contains the escape sequence \M, pcretest calls pcre_exec() several
974    times with different match limits, until it finds the minimum value needed for
975    pcre_exec() to complete. The value is then output. This can be instructive; for
976    most simple matches the number is quite small, but for pathological cases it
977    gets very large very quickly.
979    47. There's a new option for pcre_fullinfo() called PCRE_INFO_STUDYSIZE. It
980    returns the size of the data block pointed to by the study_data field in a
981    pcre_extra block, that is, the value that was passed as the argument to
982    pcre_malloc() when PCRE was getting memory in which to place the information
983    created by pcre_study(). The fourth argument should point to a size_t variable.
984    pcretest has been extended so that this information is shown after a successful
985    pcre_study() call when information about the compiled regex is being displayed.
987    48. Cosmetic change to Makefile: there's no need to have / after $(DESTDIR)
988    because what follows is always an absolute path. (Later: it turns out that this
989    is more than cosmetic for MinGW, because it doesn't like empty path
990    components.)
992    49. Some changes have been made to the callout feature (see 28 above):
994    (i)  A callout function now has three choices for what it returns:
996           0  =>  success, carry on matching
997         > 0  =>  failure at this point, but backtrack if possible
998         < 0  =>  serious error, return this value from pcre_exec()
1000         Negative values should normally be chosen from the set of PCRE_ERROR_xxx
1001         values. In particular, returning PCRE_ERROR_NOMATCH forces a standard
1002         "match failed" error. The error number PCRE_ERROR_CALLOUT is reserved for
1003         use by callout functions. It will never be used by PCRE itself.
1005    (ii) The pcre_extra structure (see 45 above) has a void * field called
1006         callout_data, with corresponding flag bit PCRE_EXTRA_CALLOUT_DATA. The
1007         pcre_callout_block structure has a field of the same name. The contents of
1008         the field passed in the pcre_extra structure are passed to the callout
1009         function in the corresponding field in the callout block. This makes it
1010         easier to use the same callout-containing regex from multiple threads. For
1011         testing, the pcretest program has a new data escape
1013           \C*n        pass the number n (may be negative) as callout_data
1015         If the callout function in pcretest receives a non-zero value as
1016         callout_data, it returns that value.
1018    50. Makefile wasn't handling CFLAGS properly when compiling dftables. Also,
1019    there were some redundant $(CFLAGS) in commands that are now specified as
1020    $(LINK), which already includes $(CFLAGS).
1022    51. Extensions to UTF-8 support are listed below. These all apply when (a) PCRE
1023    has been compiled with UTF-8 support *and* pcre_compile() has been compiled
1024    with the PCRE_UTF8 flag. Patterns that are compiled without that flag assume
1025    one-byte characters throughout. Note that case-insensitive matching applies
1026    only to characters whose values are less than 256. PCRE doesn't support the
1027    notion of cases for higher-valued characters.
1029    (i)   A character class whose characters are all within 0-255 is handled as
1030          a bit map, and the map is inverted for negative classes. Previously, a
1031          character > 255 always failed to match such a class; however it should
1032          match if the class was a negative one (e.g. [^ab]). This has been fixed.
1034    (ii)  A negated character class with a single character < 255 is coded as
1035          "not this character" (OP_NOT). This wasn't working properly when the test
1036          character was multibyte, either singly or repeated.
1038    (iii) Repeats of multibyte characters are now handled correctly in UTF-8
1039          mode, for example: \x{100}{2,3}.
1041    (iv)  The character escapes \b, \B, \d, \D, \s, \S, \w, and \W (either
1042          singly or repeated) now correctly test multibyte characters. However,
1043          PCRE doesn't recognize any characters with values greater than 255 as
1044          digits, spaces, or word characters. Such characters always match \D, \S,
1045          and \W, and never match \d, \s, or \w.
1047    (v)   Classes may now contain characters and character ranges with values
1048          greater than 255. For example: [ab\x{100}-\x{400}].
1050    (vi)  pcregrep now has a --utf-8 option (synonym -u) which makes it call
1051          PCRE in UTF-8 mode.
1053    52. The info request value PCRE_INFO_FIRSTCHAR has been renamed
1054    PCRE_INFO_FIRSTBYTE because it is a byte value. However, the old name is
1055    retained for backwards compatibility. (Note that LASTLITERAL is also a byte
1056    value.)
1058    53. The single man page has become too large. I have therefore split it up into
1059    a number of separate man pages. These also give rise to individual HTML pages;
1060    these are now put in a separate directory, and there is an index.html page that
1061    lists them all. Some hyperlinking between the pages has been installed.
1063    54. Added convenience functions for handling named capturing parentheses.
1065    55. Unknown escapes inside character classes (e.g. [\M]) and escapes that
1066    aren't interpreted therein (e.g. [\C]) are literals in Perl. This is now also
1067    true in PCRE, except when the PCRE_EXTENDED option is set, in which case they
1068    are faulted.
1070    56. Introduced HOST_CC and HOST_CFLAGS which can be set in the environment when
1071    calling configure. These values are used when compiling the dftables.c program
1072    which is run to generate the source of the default character tables. They
1073    default to the values of CC and CFLAGS. If you are cross-compiling PCRE,
1074    you will need to set these values.
1076    57. Updated the building process for Windows DLL, as provided by Fred Cox.
1079    Version 3.9 02-Jan-02
1080  ---------------------  ---------------------
1082  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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