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-revision 91 by nigel,
Sat Feb 24 21:41:34 2007 UTC
+revision 143 by ph10,
Mon Apr  2 10:08:14 2007 UTC
 Line 1
  ChangeLog for PCRE
  ------------------
+ Version 7.1 12-Mar-07
+ ---------------------
+. Applied Bob Rossi and Daniel G's patches to convert the build system to one
+     that is more "standard", making use of automake and other Autotools. There
+     is some re-arrangement of the files and adjustment of comments consequent
+     on this.
+. Part of the patch fixed a problem with the pcregrep tests. The test of -r
+     for recursive directory scanning broke on some systems because the files
+     are not scanned in any specific order and on different systems the order
+     was different. A call to "sort" has been inserted into RunGrepTest for the
+     approprate test as a short-term fix. In the longer term there may be an
+     alternative.
+. I had an email from Eric Raymond about problems translating some of PCRE's
+     man pages to HTML (despite the fact that I distribute HTML pages, some
+     people do their own conversions for various reasons). The problems
+     concerned the use of low-level troff macros .br and .in. I have therefore
+     removed all such uses from the man pages (some were redundant, some could
+     be replaced by .nf/.fi pairs). The 132html script that I use to generate
+     HTML has been updated to handle .nf/.fi and to complain if it encounters
+     .br or .in.
+. Updated comments in configure.ac that get placed in config.h.in and also
+     arranged for config.h to be included in the distribution, with the name
+     config.h.generic, for the benefit of those who have to compile without
+     Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
+. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
+     Weber: (1) pcre_internal.h was missing some function renames; (2) updated
+     makevp.bat for the current PCRE, using the additional files
+     makevp_c.txt, makevp_l.txt, and pcregexp.pas.
+. A Windows user reported a minor discrepancy with test 2, which turned out
+     to be caused by a trailing space on an input line that had got lost in his
+     copy. The trailing space was an accident, so I've just removed it.
+. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
+     that is needed.
+. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
+     as "const" (a) because they are and (b) because it helps the PHP
+     maintainers who have recently made a script to detect big data structures
+     in the php code that should be moved to the .rodata section. I remembered
+     to update Builducptable as well, so it won't revert if ucptable.h is ever
+     re-created.
+. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
+     pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
+     order to be able to cut out the UTF-8 tables in the latter when UTF-8
+     support is not required. This saves 1.5-2K of code, which is important in
+     some applications.
+     Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
+     so as not to refer to the tables, even though these functions will never be
+     called when UTF-8 support is disabled. Otherwise there are problems with a
+     shared library.
+. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
+     (a) It was defining its arguments as char * instead of void *.
+     (b) It was assuming that all moves were upwards in memory; this was true
+         a long time ago when I wrote it, but is no longer the case.
+     The emulated memove() is provided for those environments that have neither
+     memmove() nor bcopy(). I didn't think anyone used it these days, but that
+     is clearly not the case, as these two bugs were recently reported.
+. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
+     and Detrail to create the HTML documentation, the .txt form of the man
+     pages, and it removes trailing spaces from listed files. It also creates
+     pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
+     case, it wraps all the #defines with #ifndefs. This script should be run
+     before "make dist".
+. Fixed two fairly obscure bugs concerned with quantified caseless matching
+     with Unicode property support.
+     (a) For a maximizing quantifier, if the two different cases of the
+         character were of different lengths in their UTF-8 codings (there are
+         some cases like this - I found 11), and the matching function had to
+         back up over a mixture of the two cases, it incorrectly assumed they
+         were both the same length.
+     (b) When PCRE was configured to use the heap rather than the stack for
+         recursion during matching, it was not correctly preserving the data for
+         the other case of a UTF-8 character when checking ahead for a match
+         while processing a minimizing repeat. If the check also involved
+         matching a wide character, but failed, corruption could cause an
+         erroneous result when trying to check for a repeat of the original
+         character.
+. Some tidying changes to the testing mechanism:
+     (a) The RunTest script now detects the internal link size and whether there
+         is UTF-8 and UCP support by running ./pcretest -C instead of relying on
+         values substituted by "configure". (The RunGrepTest script already did
+         this for UTF-8.) The configure.ac script no longer substitutes the
+         relevant variables.
+     (b) The debugging options /B and /D in pcretest show the compiled bytecode
+         with length and offset values. This means that the output is different
+         for different internal link sizes. Test 2 is skipped for link sizes
+         other than 2 because of this, bypassing the problem. Unfortunately,
+         there was also a test in test 3 (the locale tests) that used /B and
+         failed for link sizes other than 2. Rather than cut the whole test out,
+         I have added a new /Z option to pcretest that replaces the length and
+         offset values with spaces. This is now used to make test 3 independent
+         of link size. (Test 2 will be tidied up later.)
+. If erroroffset was passed as NULL to pcre_compile, it provoked a
+     segmentation fault instead of returning the appropriate error message.
+. In multiline mode when the newline sequence was set to "any", the pattern
+     ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
+     This doesn't seem right; it now treats the CRLF combination as the line
+     ending, and so does not match in that case. It's only a pattern such as ^$
+     that would hit this one: something like ^ABC$ would have failed after \r
+     and then tried again after \r\n.
+. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
+     in an attempt to make files that differ only in their line terminators
+     compare equal. This works on Linux.
+. Under certain error circumstances pcregrep might try to free random memory
+     as it exited. This is now fixed, thanks to valgrind.
+. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
+     "abc\r\n\r\n", it found an unwanted second match after the second \r. This
+     was because its rules for how to advance for /g after matching an empty
+     string at the end of a line did not allow for this case. They now check for
+     it specially.
+ Version 7.0 19-Dec-06
+ ---------------------
+. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
+     moving to gcc 4.1.1.
+. The -S option for pcretest uses setrlimit(); I had omitted to #include
+     sys/time.h, which is documented as needed for this function. It doesn't
+     seem to matter on Linux, but it showed up on some releases of OS X.
+. It seems that there are systems where bytes whose values are greater than
+match isprint() in the "C" locale. The "C" locale should be the
+     default when a C program starts up. In most systems, only ASCII printing
+     characters match isprint(). This difference caused the output from pcretest
+     to vary, making some of the tests fail. I have changed pcretest so that:
+     (a) When it is outputting text in the compiled version of a pattern, bytes
+         other than 32-126 are always shown as hex escapes.
+     (b) When it is outputting text that is a matched part of a subject string,
+         it does the same, unless a different locale has been set for the match
+         (using the /L modifier). In this case, it uses isprint() to decide.
+. Fixed a major bug that caused incorrect computation of the amount of memory
+     required for a compiled pattern when options that changed within the
+     pattern affected the logic of the preliminary scan that determines the
+     length. The relevant options are -x, and -i in UTF-8 mode. The result was
+     that the computed length was too small. The symptoms of this bug were
+     either the PCRE error "internal error: code overflow" from pcre_compile(),
+     or a glibc crash with a message such as "pcretest: free(): invalid next
+     size (fast)". Examples of patterns that provoked this bug (shown in
+     pcretest format) are:
+       /(?-x: )/x
+       /(?x)(?-x: \s*#\s*)/
+       /((?i)[\x{c0}])/8
+       /(?i:[\x{c0}])/8
+     HOWEVER: Change 17 below makes this fix obsolete as the memory computation
+     is now done differently.
+. Applied patches from Google to: (a) add a QuoteMeta function to the C++
+     wrapper classes; (b) implement a new function in the C++ scanner that is
+     more efficient than the old way of doing things because it avoids levels of
+     recursion in the regex matching; (c) add a paragraph to the documentation
+     for the FullMatch() function.
+. The escape sequence \n was being treated as whatever was defined as
+     "newline". Not only was this contrary to the documentation, which states
+     that \n is character 10 (hex 0A), but it also went horribly wrong when
+     "newline" was defined as CRLF. This has been fixed.
+. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
+     was being set to -1 for the "end of line" case (supposedly a value that no
+     character can have). Though this value is never used (the check for end of
+     line is "zero bytes in current character"), it caused compiler complaints.
+     I've changed it to 0xffffffff.
+. In pcre_version.c, the version string was being built by a sequence of
+     C macros that, in the event of PCRE_PRERELEASE being defined as an empty
+     string (as it is for production releases) called a macro with an empty
+     argument. The C standard says the result of this is undefined. The gcc
+     compiler treats it as an empty string (which was what was wanted) but it is
+     reported that Visual C gives an error. The source has been hacked around to
+     avoid this problem.
+. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
+     builds of pcretest, and changed the call to _setmode() to use _O_BINARY
+     instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
+     of them did).
+. Originally, pcretest opened its input and output without "b"; then I was
+     told that "b" was needed in some environments, so it was added for release
+.0 to both the input and output. (It makes no difference on Unix-like
+     systems.) Later I was told that it is wrong for the input on Windows. I've
+     now abstracted the modes into two macros, to make it easier to fiddle with
+     them, and removed "b" from the input mode under Windows.
+. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
+. Added -help and --help to pcretest as an official way of being reminded
+     of the options.
+. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
+     and pcrecpp.cc because they annoy compilers at high warning levels.
+. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
+. Fixed an occurrence of == in configure.ac that should have been = (shell
+     scripts are not C programs :-) and which was not noticed because it works
+     on Linux.
+. pcretest is supposed to handle any length of pattern and data line (as one
+     line or as a continued sequence of lines) by extending its input buffer if
+     necessary. This feature was broken for very long pattern lines, leading to
+     a string of junk being passed to pcre_compile() if the pattern was longer
+     than about 50K.
+. I have done a major re-factoring of the way pcre_compile() computes the
+     amount of memory needed for a compiled pattern. Previously, there was code
+     that made a preliminary scan of the pattern in order to do this. That was
+     OK when PCRE was new, but as the facilities have expanded, it has become
+     harder and harder to keep it in step with the real compile phase, and there
+     have been a number of bugs (see for example, 4 above). I have now found a
+     cunning way of running the real compile function in a "fake" mode that
+     enables it to compute how much memory it would need, while actually only
+     ever using a few hundred bytes of working memory and without too many
+     tests of the mode. This should make future maintenance and development
+     easier. A side effect of this work is that the limit of 200 on the nesting
+     depth of parentheses has been removed (though this was never a serious
+     limitation, I suspect). However, there is a downside: pcre_compile() now
+     runs more slowly than before (30% or more, depending on the pattern). I
+     hope this isn't a big issue. There is no effect on runtime performance.
+. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
+     newline (only possible for the last line of a file) and it was a
+     pattern that set a locale (followed by /Lsomething), pcretest crashed.
+. Added additional timing features to pcretest. (1) The -tm option now times
+     matching only, not compiling. (2) Both -t and -tm can be followed, as a
+     separate command line item, by a number that specifies the number of
+     repeats to use when timing. The default is 50000; this gives better
+     precision, but takes uncomfortably long for very large patterns.
+. Extended pcre_study() to be more clever in cases where a branch of a
+     subpattern has no definite first character. For example, (a*|b*)[cd] would
+     previously give no result from pcre_study(). Now it recognizes that the
+     first character must be a, b, c, or d.
+. There was an incorrect error "recursive call could loop indefinitely" if
+     a subpattern (or the entire pattern) that was being tested for matching an
+     empty string contained only one non-empty item after a nested subpattern.
+     For example, the pattern (?>\x{100}*)\d(?R) provoked this error
+     incorrectly, because the \d was being skipped in the check.
+. The pcretest program now has a new pattern option /B and a command line
+     option -b, which is equivalent to adding /B to every pattern. This causes
+     it to show the compiled bytecode, without the additional information that
+     -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
+     is the same as /B/I).
+. A new optimization is now able automatically to treat some sequences such
+     as a*b as a*+b. More specifically, if something simple (such as a character
+     or a simple class like \d) has an unlimited quantifier, and is followed by
+     something that cannot possibly match the quantified thing, the quantifier
+     is automatically "possessified".
+. A recursive reference to a subpattern whose number was greater than 39
+     went wrong under certain circumstances in UTF-8 mode. This bug could also
+     have affected the operation of pcre_study().
+. Realized that a little bit of performance could be had by replacing
+     (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
+. Timing data from pcretest is now shown to 4 decimal places instead of 3.
+. Possessive quantifiers such as a++ were previously implemented by turning
+     them into atomic groups such as ($>a+). Now they have their own opcodes,
+     which improves performance. This includes the automatically created ones
+     from 23 above.
+. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
+     lookahead was broken if it was not anchored. PCRE was mistakenly expecting
+     the first matched character to be a colon. This applied both to named and
+     numbered groups.
+. The ucpinternal.h header file was missing its idempotency #ifdef.
+. I was sent a "project" file called libpcre.a.dev which I understand makes
+     building PCRE on Windows easier, so I have included it in the distribution.
+. There is now a check in pcretest against a ridiculously large number being
+     returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
+     loop, the loop is abandoned.
+. Forward references to subpatterns in conditions such as (?(2)...) where
+     subpattern 2 is defined later cause pcre_compile() to search forwards in
+     the pattern for the relevant set of parentheses. This search went wrong
+     when there were unescaped parentheses in a character class, parentheses
+     escaped with \Q...\E, or parentheses in a #-comment in /x mode.
+. "Subroutine" calls and backreferences were previously restricted to
+     referencing subpatterns earlier in the regex. This restriction has now
+     been removed.
+. Added a number of extra features that are going to be in Perl 5.10. On the
+     whole, these are just syntactic alternatives for features that PCRE had
+     previously implemented using the Python syntax or my own invention. The
+     other formats are all retained for compatibility.
+     (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
+         as (?P<name>...). The new forms, as well as being in Perl 5.10, are
+         also .NET compatible.
+     (b) A recursion or subroutine call to a named group can now be defined as
+         (?&name) as well as (?P>name).
+     (c) A backreference to a named group can now be defined as \k<name> or
+         \k'name' as well as (?P=name). The new forms, as well as being in Perl
+.10, are also .NET compatible.
+     (d) A conditional reference to a named group can now use the syntax
+         (?(<name>) or (?('name') as well as (?(name).
+     (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
+         groups (named and numbered) that are never evaluated inline, but can be
+         called as "subroutines" from elsewhere. In effect, the DEFINE condition
+         is always false. There may be only one alternative in such a group.
+     (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
+         as the simple (?(R). The condition is true only if the most recent
+         recursion is that of the given number or name. It does not search out
+         through the entire recursion stack.
+     (g) The escape \gN or \g{N} has been added, where N is a positive or
+         negative number, specifying an absolute or relative reference.
+. Tidied to get rid of some further signed/unsigned compiler warnings and
+     some "unreachable code" warnings.
+. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
+     things, this adds five new scripts.
+. Perl ignores orphaned \E escapes completely. PCRE now does the same.
+     There were also incompatibilities regarding the handling of \Q..\E inside
+     character classes, for example with patterns like [\Qa\E-\Qz\E] where the
+     hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
+. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
+     matches an empty string, and forcibly breaks the loop. There were bugs in
+     this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
+     against  aaaa  the result was just "a" rather than "aaaa", for example. Two
+     separate and independent bugs (that affected different cases) have been
+     fixed.
+. Refactored the code to abolish the use of different opcodes for small
+     capturing bracket numbers. This is a tidy that I avoided doing when I
+     removed the limit on the number of capturing brackets for 3.5 back in 2001.
+     The new approach is not only tidier, it makes it possible to reduce the
+     memory needed to fix the previous bug (38).
+. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
+     sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
+     processing dot, circumflex, or dollar metacharacters, or #-comments in /x
+     mode.
+. Add \R to match any Unicode newline sequence, as suggested in the Unicode
+     report.
+. Applied patch, originally from Ari Pollak, modified by Google, to allow
+     copy construction and assignment in the C++ wrapper.
+. Updated pcregrep to support "--newline=any". In the process, I fixed a
+     couple of bugs that could have given wrong results in the "--newline=crlf"
+     case.
+. Added a number of casts and did some reorganization of signed/unsigned int
+     variables following suggestions from Dair Grant. Also renamed the variable
+     "this" as "item" because it is a C++ keyword.
+. Arranged for dftables to add
+       #include "pcre_internal.h"
+     to pcre_chartables.c because without it, gcc 4.x may remove the array
+     definition from the final binary if PCRE is built into a static library and
+     dead code stripping is activated.
+. For an unanchored pattern, if a match attempt fails at the start of a
+     newline sequence, and the newline setting is CRLF or ANY, and the next two
+     characters are CRLF, advance by two characters instead of one.
  Version 6.7 04-Jul-06
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