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-revision 49 by nigel,
Sat Feb 24 21:39:33 2007 UTC
+revision 98 by ph10,
Mon Mar  5 15:55:02 2007 UTC
 Line 1
  ChangeLog for PCRE
  ------------------
+ Version 7.1 05-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.
+ 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
+ ---------------------
+. In order to handle tests when input lines are enormously long, pcretest has
+     been re-factored so that it automatically extends its buffers when
+     necessary. The code is crude, but this _is_ just a test program. The
+     default size has been increased from 32K to 50K.
+. The code in pcre_study() was using the value of the re argument before
+     testing it for NULL. (Of course, in any sensible call of the function, it
+     won't be NULL.)
+. The memmove() emulation function in pcre_internal.h, which is used on
+     systems that lack both memmove() and bcopy() - that is, hardly ever -
+     was missing a "static" storage class specifier.
+. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
+     containing an extended class (one that cannot be represented by a bitmap
+     because it contains high-valued characters or Unicode property items, e.g.
+     [\pZ]). Almost always one would set UTF-8 mode when processing such a
+     pattern, but PCRE should not loop if you do not (it no longer does).
+     [Detail: two cases were found: (a) a repeated subpattern containing an
+     extended class; (b) a recursive reference to a subpattern that followed a
+     previous extended class. It wasn't skipping over the extended class
+     correctly when UTF-8 mode was not set.]
+. A negated single-character class was not being recognized as fixed-length
+     in lookbehind assertions such as (?<=[^f]), leading to an incorrect
+     compile error "lookbehind assertion is not fixed length".
+. The RunPerlTest auxiliary script was showing an unexpected difference
+     between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
+     write a Perl script that can interpret lines of an input file either as
+     byte characters or as UTF-8, which is what "perltest" was being required to
+     do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
+     can't do is switch easily at run time between having the "use utf8;" pragma
+     or not. In the end, I fudged it by using the RunPerlTest script to insert
+     "use utf8;" explicitly for the UTF-8 tests.
+. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
+     the end of the subject string, contrary to the documentation and to what
+     Perl does. This was true of both matching functions. Now it matches only at
+     the start of the subject and immediately after *internal* newlines.
+. A call of pcre_fullinfo() from pcretest to get the option bits was passing
+     a pointer to an int instead of a pointer to an unsigned long int. This
+     caused problems on 64-bit systems.
+. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
+     instance of the 'standard' template library not being so standard".
+. There was no check on the number of named subpatterns nor the maximum
+     length of a subpattern name. The product of these values is used to compute
+     the size of the memory block for a compiled pattern. By supplying a very
+     long subpattern name and a large number of named subpatterns, the size
+     computation could be caused to overflow. This is now prevented by limiting
+     the length of names to 32 characters, and the number of named subpatterns
+     to 10,000.
+. Subpatterns that are repeated with specific counts have to be replicated in
+     the compiled pattern. The size of memory for this was computed from the
+     length of the subpattern and the repeat count. The latter is limited to
+, but there was no limit on the former, meaning that integer overflow
+     could in principle occur. The compiled length of a repeated subpattern is
+     now limited to 30,000 bytes in order to prevent this.
+. Added the optional facility to have named substrings with the same name.
+. Added the ability to use a named substring as a condition, using the
+     Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
+     are numbers (not recommended). Forward references are permitted.
+. Added forward references in named backreferences (if you see what I mean).
+. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
+     pattern could run off the end of the subject. For example, the pattern
+     "(?s)(.{1,5})"8 did this with the subject "ab".
+. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
+     PCRE_CASELESS was set when matching characters that were quantified with ?
+     or *.
+. A character class other than a single negated character that had a minimum
+     but no maximum quantifier - for example [ab]{6,} - was not handled
+     correctly by pce_dfa_exec(). It would match only one character.
+. A valid (though odd) pattern that looked like a POSIX character
+     class but used an invalid character after [ (for example [[,abc,]]) caused
+     pcre_compile() to give the error "Failed: internal error: code overflow" or
+     in some cases to crash with a glibc free() error. This could even happen if
+     the pattern terminated after [[ but there just happened to be a sequence of
+     letters, a binary zero, and a closing ] in the memory that followed.
+. Perl's treatment of octal escapes in the range \400 to \777 has changed
+     over the years. Originally (before any Unicode support), just the bottom 8
+     bits were taken. Thus, for example, \500 really meant \100. Nowadays the
+     output from "man perlunicode" includes this:
+       The regular expression compiler produces polymorphic opcodes.  That
+       is, the pattern adapts to the data and automatically switches to
+       the Unicode character scheme when presented with Unicode data--or
+       instead uses a traditional byte scheme when presented with byte
+       data.
+     Sadly, a wide octal escape does not cause a switch, and in a string with
+     no other multibyte characters, these octal escapes are treated as before.
+     Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
+     /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
+     Unicode string.
+     I have not perpetrated such confusion in PCRE. Up till now, it took just
+     the bottom 8 bits, as in old Perl. I have now made octal escapes with
+     values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
+     translate to the appropriate multibyte character.
+. Applied some refactoring to reduce the number of warnings from Microsoft
+     and Borland compilers. This has included removing the fudge introduced
+     seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
+     a warning about an unused variable.
+. PCRE has not included VT (character 0x0b) in the set of whitespace
+     characters since release 4.0, because Perl (from release 5.004) does not.
+     [Or at least, is documented not to: some releases seem to be in conflict
+     with the documentation.] However, when a pattern was studied with
+     pcre_study() and all its branches started with \s, PCRE still included VT
+     as a possible starting character. Of course, this did no harm; it just
+     caused an unnecessary match attempt.
+. Removed a now-redundant internal flag bit that recorded the fact that case
+     dependency changed within the pattern. This was once needed for "required
+     byte" processing, but is no longer used. This recovers a now-scarce options
+     bit. Also moved the least significant internal flag bit to the most-
+     significant bit of the word, which was not previously used (hangover from
+     the days when it was an int rather than a uint) to free up another bit for
+     the future.
+. Added support for CRLF line endings as well as CR and LF. As well as the
+     default being selectable at build time, it can now be changed at runtime
+     via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
+     specify that it is scanning data with non-default line endings.
+. Changed the definition of CXXLINK to make it agree with the definition of
+     LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
+. Applied Ian Taylor's patches to avoid using another stack frame for tail
+     recursions. This makes a big different to stack usage for some patterns.
+. If a subpattern containing a named recursion or subroutine reference such
+     as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
+     the space required for the compiled pattern went wrong and gave too small a
+     value. Depending on the environment, this could lead to "Failed: internal
+     error: code overflow at offset 49" or "glibc detected double free or
+     corruption" errors.
+. Applied patches from Google (a) to support the new newline modes and (b) to
+     advance over multibyte UTF-8 characters in GlobalReplace.
+. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
+     difference for some implementation of PCRE in some Windows version.
+. Added some extra testing facilities to pcretest:
+     \q<number>   in a data line sets the "match limit" value
+     \Q<number>   in a data line sets the "match recursion limt" value
+     -S <number>  sets the stack size, where <number> is in megabytes
+     The -S option isn't available for Windows.
+ Version 6.6 06-Feb-06
+ ---------------------
+. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
+     in pcreposix.h. I have copied the definition from pcre.h.
+. Change 25 for 6.5 broke compilation in a build directory out-of-tree
+     because pcre.h is no longer a built file.
+. Added Jeff Friedl's additional debugging patches to pcregrep. These are
+     not normally included in the compiled code.
+ Version 6.5 01-Feb-06
+ ---------------------
+. When using the partial match feature with pcre_dfa_exec(), it was not
+     anchoring the second and subsequent partial matches at the new starting
+     point. This could lead to incorrect results. For example, with the pattern
+     /1234/, partially matching against "123" and then "a4" gave a match.
+. Changes to pcregrep:
+     (a) All non-match returns from pcre_exec() were being treated as failures
+         to match the line. Now, unless the error is PCRE_ERROR_NOMATCH, an
+         error message is output. Some extra information is given for the
+         PCRE_ERROR_MATCHLIMIT and PCRE_ERROR_RECURSIONLIMIT errors, which are
+         probably the only errors that are likely to be caused by users (by
+         specifying a regex that has nested indefinite repeats, for instance).
+         If there are more than 20 of these errors, pcregrep is abandoned.
+     (b) A binary zero was treated as data while matching, but terminated the
+         output line if it was written out. This has been fixed: binary zeroes
+         are now no different to any other data bytes.
+     (c) Whichever of the LC_ALL or LC_CTYPE environment variables is set is
+         used to set a locale for matching. The --locale=xxxx long option has
+         been added (no short equivalent) to specify a locale explicitly on the
+         pcregrep command, overriding the environment variables.
+     (d) When -B was used with -n, some line numbers in the output were one less
+         than they should have been.
+     (e) Added the -o (--only-matching) option.
+     (f) If -A or -C was used with -c (count only), some lines of context were
+         accidentally printed for the final match.
+     (g) Added the -H (--with-filename) option.
+     (h) The combination of options -rh failed to suppress file names for files
+         that were found from directory arguments.
+     (i) Added the -D (--devices) and -d (--directories) options.
+     (j) Added the -F (--fixed-strings) option.
+     (k) Allow "-" to be used as a file name for -f as well as for a data file.
+     (l) Added the --colo(u)r option.
+     (m) Added Jeffrey Friedl's -S testing option, but within #ifdefs so that it
+         is not present by default.
+. A nasty bug was discovered in the handling of recursive patterns, that is,
+     items such as (?R) or (?1), when the recursion could match a number of
+     alternatives. If it matched one of the alternatives, but subsequently,
+     outside the recursion, there was a failure, the code tried to back up into
+     the recursion. However, because of the way PCRE is implemented, this is not
+     possible, and the result was an incorrect result from the match.
+     In order to prevent this happening, the specification of recursion has
+     been changed so that all such subpatterns are automatically treated as
+     atomic groups. Thus, for example, (?R) is treated as if it were (?>(?R)).
+. I had overlooked the fact that, in some locales, there are characters for
+     which isalpha() is true but neither isupper() nor islower() are true. In
+     the fr_FR locale, for instance, the \xAA and \xBA characters (ordmasculine
+     and ordfeminine) are like this. This affected the treatment of \w and \W
+     when they appeared in character classes, but not when they appeared outside
+     a character class. The bit map for "word" characters is now created
+     separately from the results of isalnum() instead of just taking it from the
+     upper, lower, and digit maps. (Plus the underscore character, of course.)
+. The above bug also affected the handling of POSIX character classes such as
+     [[:alpha:]] and [[:alnum:]]. These do not have their own bit maps in PCRE's
+     permanent tables. Instead, the bit maps for such a class were previously
+     created as the appropriate unions of the upper, lower, and digit bitmaps.
+     Now they are created by subtraction from the [[:word:]] class, which has
+     its own bitmap.
+. The [[:blank:]] character class matches horizontal, but not vertical space.
+     It is created by subtracting the vertical space characters (\x09, \x0a,
+     \x0b, \x0c) from the [[:space:]] bitmap. Previously, however, the
+     subtraction was done in the overall bitmap for a character class, meaning
+     that a class such as [\x0c[:blank:]] was incorrect because \x0c would not
+     be recognized. This bug has been fixed.
+. Patches from the folks at Google:
+       (a) pcrecpp.cc: "to handle a corner case that may or may not happen in
+       real life, but is still worth protecting against".
+       (b) pcrecpp.cc: "corrects a bug when negative radixes are used with
+       regular expressions".
+       (c) pcre_scanner.cc: avoid use of std::count() because not all systems
+       have it.
+       (d) Split off pcrecpparg.h from pcrecpp.h and had the former built by
+       "configure" and the latter not, in order to fix a problem somebody had
+       with compiling the Arg class on HP-UX.
+       (e) Improve the error-handling of the C++ wrapper a little bit.
+       (f) New tests for checking recursion limiting.
+. The pcre_memmove() function, which is used only if the environment does not
+     have a standard memmove() function (and is therefore rarely compiled),
+     contained two bugs: (a) use of int instead of size_t, and (b) it was not
+     returning a result (though PCRE never actually uses the result).
+. In the POSIX regexec() interface, if nmatch is specified as a ridiculously
+     large number - greater than INT_MAX/(3*sizeof(int)) - REG_ESPACE is
+     returned instead of calling malloc() with an overflowing number that would
+     most likely cause subsequent chaos.
+. The debugging option of pcretest was not showing the NO_AUTO_CAPTURE flag.
+. The POSIX flag REG_NOSUB is now supported. When a pattern that was compiled
+     with this option is matched, the nmatch and pmatch options of regexec() are
+     ignored.
+. Added REG_UTF8 to the POSIX interface. This is not defined by POSIX, but is
+     provided in case anyone wants to the the POSIX interface with UTF-8
+     strings.
+. Added CXXLDFLAGS to the Makefile parameters to provide settings only on the
+     C++ linking (needed for some HP-UX environments).
+. Avoid compiler warnings in get_ucpname() when compiled without UCP support
+     (unused parameter) and in the pcre_printint() function (omitted "default"
+     switch label when the default is to do nothing).
+. Added some code to make it possible, when PCRE is compiled as a C++
+     library, to replace subject pointers for pcre_exec() with a smart pointer
+     class, thus making it possible to process discontinuous strings.
+. The two macros PCRE_EXPORT and PCRE_DATA_SCOPE are confusing, and perform
+     much the same function. They were added by different people who were trying
+     to make PCRE easy to compile on non-Unix systems. It has been suggested
+     that PCRE_EXPORT be abolished now that there is more automatic apparatus
+     for compiling on Windows systems. I have therefore replaced it with
+     PCRE_DATA_SCOPE. This is set automatically for Windows; if not set it
+     defaults to "extern" for C or "extern C" for C++, which works fine on
+     Unix-like systems. It is now possible to override the value of PCRE_DATA_
+     SCOPE with something explicit in config.h. In addition:
+     (a) pcreposix.h still had just "extern" instead of either of these macros;
+         I have replaced it with PCRE_DATA_SCOPE.
+     (b) Functions such as _pcre_xclass(), which are internal to the library,
+         but external in the C sense, all had PCRE_EXPORT in their definitions.
+         This is apparently wrong for the Windows case, so I have removed it.
+         (It makes no difference on Unix-like systems.)
+. Added a new limit, MATCH_LIMIT_RECURSION, which limits the depth of nesting
+     of recursive calls to match(). This is different to MATCH_LIMIT because
+     that limits the total number of calls to match(), not all of which increase
+     the depth of recursion. Limiting the recursion depth limits the amount of
+     stack (or heap if NO_RECURSE is set) that is used. The default can be set
+     when PCRE is compiled, and changed at run time. A patch from Google adds
+     this functionality to the C++ interface.
+. Changes to the handling of Unicode character properties:
+     (a) Updated the table to Unicode 4.1.0.
+     (b) Recognize characters that are not in the table as "Cn" (undefined).
+     (c) I revised the way the table is implemented to a much improved format
+         which includes recognition of ranges. It now supports the ranges that
+         are defined in UnicodeData.txt, and it also amalgamates other
+         characters into ranges. This has reduced the number of entries in the
+         table from around 16,000 to around 3,000, thus reducing its size
+         considerably. I realized I did not need to use a tree structure after
+         all - a binary chop search is just as efficient. Having reduced the
+         number of entries, I extended their size from 6 bytes to 8 bytes to
+         allow for more data.
+     (d) Added support for Unicode script names via properties such as \p{Han}.
+. In UTF-8 mode, a backslash followed by a non-Ascii character was not
+     matching that character.
+. When matching a repeated Unicode property with a minimum greater than zero,
+     (for example \pL{2,}), PCRE could look past the end of the subject if it
+     reached it while seeking the minimum number of characters. This could
+     happen only if some of the characters were more than one byte long, because
+     there is a check for at least the minimum number of bytes.
+. Refactored the implementation of \p and \P so as to be more general, to
+     allow for more different types of property in future. This has changed the
+     compiled form incompatibly. Anybody with saved compiled patterns that use
+     \p or \P will have to recompile them.
+. Added "Any" and "L&" to the supported property types.
+. Recognize \x{...} as a code point specifier, even when not in UTF-8 mode,
+     but give a compile time error if the value is greater than 0xff.
+. The man pages for pcrepartial, pcreprecompile, and pcre_compile2 were
+     accidentally not being installed or uninstalled.
+. The pcre.h file was built from pcre.h.in, but the only changes that were
+     made were to insert the current release number. This seemed silly, because
+     it made things harder for people building PCRE on systems that don't run
+     "configure". I have turned pcre.h into a distributed file, no longer built
+     by "configure", with the version identification directly included. There is
+     no longer a pcre.h.in file.
+     However, this change necessitated a change to the pcre-config script as
+     well. It is built from pcre-config.in, and one of the substitutions was the
+     release number. I have updated configure.ac so that ./configure now finds
+     the release number by grepping pcre.h.
+. Added the ability to run the tests under valgrind.
+ Version 6.4 05-Sep-05
+ ---------------------
+. Change 6.0/10/(l) to pcregrep introduced a bug that caused separator lines
+     "--" to be printed when multiple files were scanned, even when none of the
+     -A, -B, or -C options were used. This is not compatible with Gnu grep, so I
+     consider it to be a bug, and have restored the previous behaviour.
+. A couple of code tidies to get rid of compiler warnings.
+. The pcretest program used to cheat by referring to symbols in the library
+     whose names begin with _pcre_. These are internal symbols that are not
+     really supposed to be visible externally, and in some environments it is
+     possible to suppress them. The cheating is now confined to including
+     certain files from the library's source, which is a bit cleaner.
+. Renamed pcre.in as pcre.h.in to go with pcrecpp.h.in; it also makes the
+     file's purpose clearer.
+. Reorganized pcre_ucp_findchar().
+ Version 6.3 15-Aug-05
+ ---------------------
+. The file libpcre.pc.in did not have general read permission in the tarball.
+. There were some problems when building without C++ support:
+     (a) If C++ support was not built, "make install" and "make test" still
+         tried to test it.
+     (b) There were problems when the value of CXX was explicitly set. Some
+         changes have been made to try to fix these, and ...
+     (c) --disable-cpp can now be used to explicitly disable C++ support.
+     (d) The use of @CPP_OBJ@ directly caused a blank line preceded by a
+         backslash in a target when C++ was disabled. This confuses some
+         versions of "make", apparently. Using an intermediate variable solves
+         this. (Same for CPP_LOBJ.)
+. $(LINK_FOR_BUILD) now includes $(CFLAGS_FOR_BUILD) and $(LINK)
+     (non-Windows) now includes $(CFLAGS) because these flags are sometimes
+     necessary on certain architectures.
+. Added a setting of -export-symbols-regex to the link command to remove
+     those symbols that are exported in the C sense, but actually are local
+     within the library, and not documented. Their names all begin with
+     "_pcre_". This is not a perfect job, because (a) we have to except some
+     symbols that pcretest ("illegally") uses, and (b) the facility isn't always
+     available (and never for static libraries). I have made a note to try to
+     find a way round (a) in the future.
+ Version 6.2 01-Aug-05
+ ---------------------
+. There was no test for integer overflow of quantifier values. A construction
+     such as {1111111111111111} would give undefined results. What is worse, if
+     a minimum quantifier for a parenthesized subpattern overflowed and became
+     negative, the calculation of the memory size went wrong. This could have
+     led to memory overwriting.
+. Building PCRE using VPATH was broken. Hopefully it is now fixed.
+. Added "b" to the 2nd argument of fopen() in dftables.c, for non-Unix-like
+     operating environments where this matters.
+. Applied Giuseppe Maxia's patch to add additional features for controlling
+     PCRE options from within the C++ wrapper.
+. Named capturing subpatterns were not being correctly counted when a pattern
+     was compiled. This caused two problems: (a) If there were more than 100
+     such subpatterns, the calculation of the memory needed for the whole
+     compiled pattern went wrong, leading to an overflow error. (b) Numerical
+     back references of the form \12, where the number was greater than 9, were
+     not recognized as back references, even though there were sufficient
+     previous subpatterns.
+. Two minor patches to pcrecpp.cc in order to allow it to compile on older
+     versions of gcc, e.g. 2.95.4.
+ Version 6.1 21-Jun-05
+ ---------------------
+. There was one reference to the variable "posix" in pcretest.c that was not
+     surrounded by "#if !defined NOPOSIX".
+. Make it possible to compile pcretest without DFA support, UTF8 support, or
+     the cross-check on the old pcre_info() function, for the benefit of the
+     cut-down version of PCRE that is currently imported into Exim.
+. A (silly) pattern starting with (?i)(?-i) caused an internal space
+     allocation error. I've done the easy fix, which wastes 2 bytes for sensible
+     patterns that start (?i) but I don't think that matters. The use of (?i) is
+     just an example; this all applies to the other options as well.
+. Since libtool seems to echo the compile commands it is issuing, the output
+     from "make" can be reduced a bit by putting "@" in front of each libtool
+     compile command.
+. Patch from the folks at Google for configure.in to be a bit more thorough
+     in checking for a suitable C++ installation before trying to compile the
+     C++ stuff. This should fix a reported problem when a compiler was present,
+     but no suitable headers.
+. The man pages all had just "PCRE" as their title. I have changed them to
+     be the relevant file name. I have also arranged that these names are
+     retained in the file doc/pcre.txt, which is a concatenation in text format
+     of all the man pages except the little individual ones for each function.
+. The NON-UNIX-USE file had not been updated for the different set of source
+     files that come with release 6. I also added a few comments about the C++
+     wrapper.
+ Version 6.0 07-Jun-05
+ ---------------------
+. Some minor internal re-organization to help with my DFA experiments.
+. Some missing #ifdef SUPPORT_UCP conditionals in pcretest and printint that
+     didn't matter for the library itself when fully configured, but did matter
+     when compiling without UCP support, or within Exim, where the ucp files are
+     not imported.
+. Refactoring of the library code to split up the various functions into
+     different source modules. The addition of the new DFA matching code (see
+     below) to a single monolithic source would have made it really too
+     unwieldy, quite apart from causing all the code to be include in a
+     statically linked application, when only some functions are used. This is
+     relevant even without the DFA addition now that patterns can be compiled in
+     one application and matched in another.
+     The downside of splitting up is that there have to be some external
+     functions and data tables that are used internally in different modules of
+     the library but which are not part of the API. These have all had their
+     names changed to start with "_pcre_" so that they are unlikely to clash
+     with other external names.
+. Added an alternate matching function, pcre_dfa_exec(), which matches using
+     a different (DFA) algorithm. Although it is slower than the original
+     function, it does have some advantages for certain types of matching
+     problem.
+. Upgrades to pcretest in order to test the features of pcre_dfa_exec(),
+     including restarting after a partial match.
+. A patch for pcregrep that defines INVALID_FILE_ATTRIBUTES if it is not
+     defined when compiling for Windows was sent to me. I have put it into the
+     code, though I have no means of testing or verifying it.
+. Added the pcre_refcount() auxiliary function.
+. Added the PCRE_FIRSTLINE option. This constrains an unanchored pattern to
+     match before or at the first newline in the subject string. In pcretest,
+     the /f option on a pattern can be used to set this.
+. A repeated \w when used in UTF-8 mode with characters greater than 256
+     would behave wrongly. This has been present in PCRE since release 4.0.
+. A number of changes to the pcregrep command:
+     (a) Refactored how -x works; insert ^(...)$ instead of setting
+         PCRE_ANCHORED and checking the length, in preparation for adding
+         something similar for -w.
+     (b) Added the -w (match as a word) option.
+     (c) Refactored the way lines are read and buffered so as to have more
+         than one at a time available.
+     (d) Implemented a pcregrep test script.
+     (e) Added the -M (multiline match) option. This allows patterns to match
+         over several lines of the subject. The buffering ensures that at least
+K, or the rest of the document (whichever is the shorter) is available
+         for matching (and similarly the previous 8K for lookbehind assertions).
+     (f) Changed the --help output so that it now says
+           -w, --word-regex(p)
+         instead of two lines, one with "regex" and the other with "regexp"
+         because that confused at least one person since the short forms are the
+         same. (This required a bit of code, as the output is generated
+         automatically from a table. It wasn't just a text change.)
+     (g) -- can be used to terminate pcregrep options if the next thing isn't an
+         option but starts with a hyphen. Could be a pattern or a path name
+         starting with a hyphen, for instance.
+     (h) "-" can be given as a file name to represent stdin.
+     (i) When file names are being printed, "(standard input)" is used for
+         the standard input, for compatibility with GNU grep. Previously
+         "<stdin>" was used.
+     (j) The option --label=xxx can be used to supply a name to be used for
+         stdin when file names are being printed. There is no short form.
+     (k) Re-factored the options decoding logic because we are going to add
+         two more options that take data. Such options can now be given in four
+         different ways, e.g. "-fname", "-f name", "--file=name", "--file name".
+     (l) Added the -A, -B, and -C options for requesting that lines of context
+         around matches be printed.
+     (m) Added the -L option to print the names of files that do not contain
+         any matching lines, that is, the complement of -l.
+     (n) The return code is 2 if any file cannot be opened, but pcregrep does
+         continue to scan other files.
+     (o) The -s option was incorrectly implemented. For compatibility with other
+         greps, it now suppresses the error message for a non-existent or non-
+         accessible file (but not the return code). There is a new option called
+         -q that suppresses the output of matching lines, which was what -s was
+         previously doing.
+     (p) Added --include and --exclude options to specify files for inclusion
+         and exclusion when recursing.
+. The Makefile was not using the Autoconf-supported LDFLAGS macro properly.
+     Hopefully, it now does.
+. Missing cast in pcre_study().
+. Added an "uninstall" target to the makefile.
+. Replaced "extern" in the function prototypes in Makefile.in with
+     "PCRE_DATA_SCOPE", which defaults to 'extern' or 'extern "C"' in the Unix
+     world, but is set differently for Windows.
+. Added a second compiling function called pcre_compile2(). The only
+     difference is that it has an extra argument, which is a pointer to an
+     integer error code. When there is a compile-time failure, this is set
+     non-zero, in addition to the error test pointer being set to point to an
+     error message. The new argument may be NULL if no error number is required
+     (but then you may as well call pcre_compile(), which is now just a
+     wrapper). This facility is provided because some applications need a
+     numeric error indication, but it has also enabled me to tidy up the way
+     compile-time errors are handled in the POSIX wrapper.
+. Added VPATH=.libs to the makefile; this should help when building with one
+     prefix path and installing with another. (Or so I'm told by someone who
+     knows more about this stuff than I do.)
+. Added a new option, REG_DOTALL, to the POSIX function regcomp(). This
+     passes PCRE_DOTALL to the pcre_compile() function, making the "." character
+     match everything, including newlines. This is not POSIX-compatible, but
+     somebody wanted the feature. From pcretest it can be activated by using
+     both the P and the s flags.
+. AC_PROG_LIBTOOL appeared twice in Makefile.in. Removed one.
+. libpcre.pc was being incorrectly installed as executable.
+. A couple of places in pcretest check for end-of-line by looking for '\n';
+     it now also looks for '\r' so that it will work unmodified on Windows.
+. Added Google's contributed C++ wrapper to the distribution.
+. Added some untidy missing memory free() calls in pcretest, to keep
+     Electric Fence happy when testing.
+ Version 5.0 13-Sep-04
+ ---------------------
+. Internal change: literal characters are no longer packed up into items
+     containing multiple characters in a single byte-string. Each character
+     is now matched using a separate opcode. However, there may be more than one
+     byte in the character in UTF-8 mode.
+. The pcre_callout_block structure has two new fields: pattern_position and
+     next_item_length. These contain the offset in the pattern to the next match
+     item, and its length, respectively.
+. The PCRE_AUTO_CALLOUT option for pcre_compile() requests the automatic
+     insertion of callouts before each pattern item. Added the /C option to
+     pcretest to make use of this.
+. On the advice of a Windows user, the lines
+       #if defined(_WIN32) || defined(WIN32)
+       _setmode( _fileno( stdout ), 0x8000 );
+       #endif  /* defined(_WIN32) || defined(WIN32) */
+     have been added to the source of pcretest. This apparently does useful
+     magic in relation to line terminators.
+. Changed "r" and "w" in the calls to fopen() in pcretest to "rb" and "wb"
+     for the benefit of those environments where the "b" makes a difference.
+. The icc compiler has the same options as gcc, but "configure" doesn't seem
+     to know about it. I have put a hack into configure.in that adds in code
+     to set GCC=yes if CC=icc. This seems to end up at a point in the
+     generated configure script that is early enough to affect the setting of
+     compiler options, which is what is needed, but I have no means of testing
+     whether it really works. (The user who reported this had patched the
+     generated configure script, which of course I cannot do.)
+     LATER: After change 22 below (new libtool files), the configure script
+     seems to know about icc (and also ecc). Therefore, I have commented out
+     this hack in configure.in.
+. Added support for pkg-config (2 patches were sent in).
+. Negated POSIX character classes that used a combination of internal tables
+     were completely broken. These were [[:^alpha:]], [[:^alnum:]], and
+     [[:^ascii]]. Typically, they would match almost any characters. The other
+     POSIX classes were not broken in this way.
+. Matching the pattern "\b.*?" against "ab cd", starting at offset 1, failed
+     to find the match, as PCRE was deluded into thinking that the match had to
+     start at the start point or following a newline. The same bug applied to
+     patterns with negative forward assertions or any backward assertions
+     preceding ".*" at the start, unless the pattern required a fixed first
+     character. This was a failing pattern: "(?!.bcd).*". The bug is now fixed.
+. In UTF-8 mode, when moving forwards in the subject after a failed match
+     starting at the last subject character, bytes beyond the end of the subject
+     string were read.
+. Renamed the variable "class" as "classbits" to make life easier for C++
+     users. (Previously there was a macro definition, but it apparently wasn't
+     enough.)
+. Added the new field "tables" to the extra data so that tables can be passed
+     in at exec time, or the internal tables can be re-selected. This allows
+     a compiled regex to be saved and re-used at a later time by a different
+     program that might have everything at different addresses.
+. Modified the pcre-config script so that, when run on Solaris, it shows a
+     -R library as well as a -L library.
+. The debugging options of pcretest (-d on the command line or D on a
+     pattern) showed incorrect output for anything following an extended class
+     that contained multibyte characters and which was followed by a quantifier.
+. Added optional support for general category Unicode character properties
+     via the \p, \P, and \X escapes. Unicode property support implies UTF-8
+     support. It adds about 90K to the size of the library. The meanings of the
+     inbuilt class escapes such as \d and \s have NOT been changed.
+. Updated pcredemo.c to include calls to free() to release the memory for the
+     compiled pattern.
+. The generated file chartables.c was being created in the source directory
+     instead of in the building directory. This caused the build to fail if the
+     source directory was different from the building directory, and was
+     read-only.
+. Added some sample Win commands from Mark Tetrode into the NON-UNIX-USE
+     file. No doubt somebody will tell me if they don't make sense... Also added
+     Dan Mooney's comments about building on OpenVMS.
+. Added support for partial matching via the PCRE_PARTIAL option for
+     pcre_exec() and the \P data escape in pcretest.
+. Extended pcretest with 3 new pattern features:
+     (i)   A pattern option of the form ">rest-of-line" causes pcretest to
+           write the compiled pattern to the file whose name is "rest-of-line".
+           This is a straight binary dump of the data, with the saved pointer to
+           the character tables forced to be NULL. The study data, if any, is
+           written too. After writing, pcretest reads a new pattern.
+     (ii)  If, instead of a pattern, "<rest-of-line" is given, pcretest reads a
+           compiled pattern from the given file. There must not be any
+           occurrences of "<" in the file name (pretty unlikely); if there are,
+           pcretest will instead treat the initial "<" as a pattern delimiter.
+           After reading in the pattern, pcretest goes on to read data lines as
+           usual.
+     (iii) The F pattern option causes pcretest to flip the bytes in the 32-bit
+           and 16-bit fields in a compiled pattern, to simulate a pattern that
+           was compiled on a host of opposite endianness.
+. The pcre-exec() function can now cope with patterns that were compiled on
+     hosts of opposite endianness, with this restriction:
+       As for any compiled expression that is saved and used later, the tables
+       pointer field cannot be preserved; the extra_data field in the arguments
+       to pcre_exec() should be used to pass in a tables address if a value
+       other than the default internal tables were used at compile time.
+. Calling pcre_exec() with a negative value of the "ovecsize" parameter is
+     now diagnosed as an error. Previously, most of the time, a negative number
+     would have been treated as zero, but if in addition "ovector" was passed as
+     NULL, a crash could occur.
+. Updated the files ltmain.sh, config.sub, config.guess, and aclocal.m4 with
+     new versions from the libtool 1.5 distribution (the last one is a copy of
+     a file called libtool.m4). This seems to have fixed the need to patch
+     "configure" to support Darwin 1.3 (which I used to do). However, I still
+     had to patch ltmain.sh to ensure that ${SED} is set (it isn't on my
+     workstation).
+. Changed the PCRE licence to be the more standard "BSD" licence.
+ Version 4.5 01-Dec-03
+ ---------------------
+. There has been some re-arrangement of the code for the match() function so
+     that it can be compiled in a version that does not call itself recursively.
+     Instead, it keeps those local variables that need separate instances for
+     each "recursion" in a frame on the heap, and gets/frees frames whenever it
+     needs to "recurse". Keeping track of where control must go is done by means
+     of setjmp/longjmp. The whole thing is implemented by a set of macros that
+     hide most of the details from the main code, and operates only if
+     NO_RECURSE is defined while compiling pcre.c. If PCRE is built using the
+     "configure" mechanism, "--disable-stack-for-recursion" turns on this way of
+     operating.
+     To make it easier for callers to provide specially tailored get/free
+     functions for this usage, two new functions, pcre_stack_malloc, and
+     pcre_stack_free, are used. They are always called in strict stacking order,
+     and the size of block requested is always the same.
+     The PCRE_CONFIG_STACKRECURSE info parameter can be used to find out whether
+     PCRE has been compiled to use the stack or the heap for recursion. The
+     -C option of pcretest uses this to show which version is compiled.
+     A new data escape \S, is added to pcretest; it causes the amounts of store
+     obtained and freed by both kinds of malloc/free at match time to be added
+     to the output.
+. Changed the locale test to use "fr_FR" instead of "fr" because that's
+     what's available on my current Linux desktop machine.
+. When matching a UTF-8 string, the test for a valid string at the start has
+     been extended. If start_offset is not zero, PCRE now checks that it points
+     to a byte that is the start of a UTF-8 character. If not, it returns
+     PCRE_ERROR_BADUTF8_OFFSET (-11). Note: the whole string is still checked;
+     this is necessary because there may be backward assertions in the pattern.
+     When matching the same subject several times, it may save resources to use
+     PCRE_NO_UTF8_CHECK on all but the first call if the string is long.
+. The code for checking the validity of UTF-8 strings has been tightened so
+     that it rejects (a) strings containing 0xfe or 0xff bytes and (b) strings
+     containing "overlong sequences".
+. Fixed a bug (appearing twice) that I could not find any way of exploiting!
+     I had written "if ((digitab[*p++] && chtab_digit) == 0)" where the "&&"
+     should have been "&", but it just so happened that all the cases this let
+     through by mistake were picked up later in the function.
+. I had used a variable called "isblank" - this is a C99 function, causing
+     some compilers to warn. To avoid this, I renamed it (as "blankclass").
+. Cosmetic: (a) only output another newline at the end of pcretest if it is
+     prompting; (b) run "./pcretest /dev/null" at the start of the test script
+     so the version is shown; (c) stop "make test" echoing "./RunTest".
+. Added patches from David Burgess to enable PCRE to run on EBCDIC systems.
+. The prototype for memmove() for systems that don't have it was using
+     size_t, but the inclusion of the header that defines size_t was later. I've
+     moved the #includes for the C headers earlier to avoid this.
+. Added some adjustments to the code to make it easier to compiler on certain
+     special systems:
+       (a) Some "const" qualifiers were missing.
+       (b) Added the macro EXPORT before all exported functions; by default this
+           is defined to be empty.
+       (c) Changed the dftables auxiliary program (that builds chartables.c) so
+           that it reads its output file name as an argument instead of writing
+           to the standard output and assuming this can be redirected.
+. In UTF-8 mode, if a recursive reference (e.g. (?1)) followed a character
+     class containing characters with values greater than 255, PCRE compilation
+     went into a loop.
+. A recursive reference to a subpattern that was within another subpattern
+     that had a minimum quantifier of zero caused PCRE to crash. For example,
+     (x(y(?2))z)? provoked this bug with a subject that got as far as the
+     recursion. If the recursively-called subpattern itself had a zero repeat,
+     that was OK.
+. In pcretest, the buffer for reading a data line was set at 30K, but the
+     buffer into which it was copied (for escape processing) was still set at
+, so long lines caused crashes.
+. A pattern such as /[ab]{1,3}+/ failed to compile, giving the error
+     "internal error: code overflow...". This applied to any character class
+     that was followed by a possessive quantifier.
+. Modified the Makefile to add libpcre.la as a prerequisite for
+     libpcreposix.la because I was told this is needed for a parallel build to
+     work.
+. If a pattern that contained .* following optional items at the start was
+     studied, the wrong optimizing data was generated, leading to matching
+     errors. For example, studying /[ab]*.*c/ concluded, erroneously, that any
+     matching string must start with a or b or c. The correct conclusion for
+     this pattern is that a match can start with any character.
+ Version 4.4 13-Aug-03
+ ---------------------
+. In UTF-8 mode, a character class containing characters with values between
+and 255 was not handled correctly if the compiled pattern was studied.
+     In fixing this, I have also improved the studying algorithm for such
+     classes (slightly).
+. Three internal functions had redundant arguments passed to them. Removal
+     might give a very teeny performance improvement.
+. Documentation bug: the value of the capture_top field in a callout is *one
+     more than* the number of the hightest numbered captured substring.
+. The Makefile linked pcretest and pcregrep with -lpcre, which could result
+     in incorrectly linking with a previously installed version. They now link
+     explicitly with libpcre.la.
+. configure.in no longer needs to recognize Cygwin specially.
+. A problem in pcre.in for Windows platforms is fixed.
+. If a pattern was successfully studied, and the -d (or /D) flag was given to
+     pcretest, it used to include the size of the study block as part of its
+     output. Unfortunately, the structure contains a field that has a different
+     size on different hardware architectures. This meant that the tests that
+     showed this size failed. As the block is currently always of a fixed size,
+     this information isn't actually particularly useful in pcretest output, so
+     I have just removed it.
+. Three pre-processor statements accidentally did not start in column 1.
+     Sadly, there are *still* compilers around that complain, even though
+     standard C has not required this for well over a decade. Sigh.
+. In pcretest, the code for checking callouts passed small integers in the
+     callout_data field, which is a void * field. However, some picky compilers
+     complained about the casts involved for this on 64-bit systems. Now
+     pcretest passes the address of the small integer instead, which should get
+     rid of the warnings.
+. By default, when in UTF-8 mode, PCRE now checks for valid UTF-8 strings at
+     both compile and run time, and gives an error if an invalid UTF-8 sequence
+     is found. There is a option for disabling this check in cases where the
+     string is known to be correct and/or the maximum performance is wanted.
+. In response to a bug report, I changed one line in Makefile.in from
+         -Wl,--out-implib,.libs/lib@WIN_PREFIX@pcreposix.dll.a \
+     to
+         -Wl,--out-implib,.libs/@WIN_PREFIX@libpcreposix.dll.a \
+     to look similar to other lines, but I have no way of telling whether this
+     is the right thing to do, as I do not use Windows. No doubt I'll get told
+     if it's wrong...
+ Version 4.3 21-May-03
+ ---------------------
+. Two instances of @WIN_PREFIX@ omitted from the Windows targets in the
+    Makefile.
+. Some refactoring to improve the quality of the code:
+    (i)   The utf8_table... variables are now declared "const".
+    (ii)  The code for \cx, which used the "case flipping" table to upper case
+          lower case letters, now just substracts 32. This is ASCII-specific,
+          but the whole concept of \cx is ASCII-specific, so it seems
+          reasonable.
+    (iii) PCRE was using its character types table to recognize decimal and
+          hexadecimal digits in the pattern. This is silly, because it handles
+          only 0-9, a-f, and A-F, but the character types table is locale-
+          specific, which means strange things might happen. A private
+          table is now used for this - though it costs 256 bytes, a table is
+          much faster than multiple explicit tests. Of course, the standard
+          character types table is still used for matching digits in subject
+          strings against \d.
+    (iv)  Strictly, the identifier ESC_t is reserved by POSIX (all identifiers
+          ending in _t are). So I've renamed it as ESC_tee.
+. The first argument for regexec() in the POSIX wrapper should have been
+    defined as "const".
+. Changed pcretest to use malloc() for its buffers so that they can be
+    Electric Fenced for debugging.
+. There were several places in the code where, in UTF-8 mode, PCRE would try
+    to read one or more bytes before the start of the subject string. Often this
+    had no effect on PCRE's behaviour, but in some circumstances it could
+    provoke a segmentation fault.
+. A lookbehind at the start of a pattern in UTF-8 mode could also cause PCRE
+    to try to read one or more bytes before the start of the subject string.
+. A lookbehind in a pattern matched in non-UTF-8 mode on a PCRE compiled with
+    UTF-8 support could misbehave in various ways if the subject string
+    contained bytes with the 0x80 bit set and the 0x40 bit unset in a lookbehind
+    area. (PCRE was not checking for the UTF-8 mode flag, and trying to move
+    back over UTF-8 characters.)
+ Version 4.2 14-Apr-03
+ ---------------------
+. Typo "#if SUPPORT_UTF8" instead of "#ifdef SUPPORT_UTF8" fixed.
+. Changes to the building process, supplied by Ronald Landheer-Cieslak
+      [ON_WINDOWS]: new variable, "#" on non-Windows platforms
+      [NOT_ON_WINDOWS]: new variable, "#" on Windows platforms
+      [WIN_PREFIX]: new variable, "cyg" for Cygwin
+      * Makefile.in: use autoconf substitution for OBJEXT, EXEEXT, BUILD_OBJEXT
+        and BUILD_EXEEXT
+      Note: automatic setting of the BUILD variables is not yet working
+      set CPPFLAGS and BUILD_CPPFLAGS (but don't use yet) - should be used at
+        compile-time but not at link-time
+      [LINK]: use for linking executables only
+      make different versions for Windows and non-Windows
+      [LINKLIB]: new variable, copy of UNIX-style LINK, used for linking
+        libraries
+      [LINK_FOR_BUILD]: new variable
+      [OBJEXT]: use throughout
+      [EXEEXT]: use throughout
+      <winshared>: new target
+      <wininstall>: new target
+      <dftables.o>: use native compiler
+      <dftables>: use native linker
+      <install>: handle Windows platform correctly
+      <clean>: ditto
+      <check>: ditto
+      copy DLL to top builddir before testing
+    As part of these changes, -no-undefined was removed again. This was reported
+    to give trouble on HP-UX 11.0, so getting rid of it seems like a good idea
+    in any case.
+. Some tidies to get rid of compiler warnings:
+    . In the match_data structure, match_limit was an unsigned long int, whereas
+      match_call_count was an int. I've made them both unsigned long ints.
+    . In pcretest the fact that a const uschar * doesn't automatically cast to
+      a void * provoked a warning.
+    . Turning on some more compiler warnings threw up some "shadow" variables
+      and a few more missing casts.
+. If PCRE was complied with UTF-8 support, but called without the PCRE_UTF8
+    option, a class that contained a single character with a value between 128
+    and 255 (e.g. /[\xFF]/) caused PCRE to crash.
+. If PCRE was compiled with UTF-8 support, but called without the PCRE_UTF8
+    option, a class that contained several characters, but with at least one
+    whose value was between 128 and 255 caused PCRE to crash.
+ Version 4.1 12-Mar-03
+ ---------------------
+. Compiling with gcc -pedantic found a couple of places where casts were
+ needed, and a string in dftables.c that was longer than standard compilers are
+ required to support.
+. Compiling with Sun's compiler found a few more places where the code could
+ be tidied up in order to avoid warnings.
+. The variables for cross-compiling were called HOST_CC and HOST_CFLAGS; the
+ first of these names is deprecated in the latest Autoconf in favour of the name
+ CC_FOR_BUILD, because "host" is typically used to mean the system on which the
+ compiled code will be run. I can't find a reference for HOST_CFLAGS, but by
+ analogy I have changed it to CFLAGS_FOR_BUILD.
+. Added -no-undefined to the linking command in the Makefile, because this is
+ apparently helpful for Windows. To make it work, also added "-L. -lpcre" to the
+ linking step for the pcreposix library.
+. PCRE was failing to diagnose the case of two named groups with the same
+ name.
+. A problem with one of PCRE's optimizations was discovered. PCRE remembers a
+ literal character that is needed in the subject for a match, and scans along to
+ ensure that it is present before embarking on the full matching process. This
+ saves time in cases of nested unlimited repeats that are never going to match.
+ Problem: the scan can take a lot of time if the subject is very long (e.g.
+ megabytes), thus penalizing straightforward matches. It is now done only if the
+ amount of subject to be scanned is less than 1000 bytes.
+. A lesser problem with the same optimization is that it was recording the
+ first character of an anchored pattern as "needed", thus provoking a search
+ right along the subject, even when the first match of the pattern was going to
+ fail. The "needed" character is now not set for anchored patterns, unless it
+ follows something in the pattern that is of non-fixed length. Thus, it still
+ fulfils its original purpose of finding quick non-matches in cases of nested
+ unlimited repeats, but isn't used for simple anchored patterns such as /^abc/.
+ Version 4.0 17-Feb-03
+ ---------------------
+. If a comment in an extended regex that started immediately after a meta-item
+ extended to the end of string, PCRE compiled incorrect data. This could lead to
+ all kinds of weird effects. Example: /#/ was bad; /()#/ was bad; /a#/ was not.
+. Moved to autoconf 2.53 and libtool 1.4.2.
+. Perl 5.8 no longer needs "use utf8" for doing UTF-8 things. Consequently,
+ the special perltest8 script is no longer needed - all the tests can be run
+ from a single perltest script.
+. From 5.004, Perl has not included the VT character (0x0b) in the set defined
+ by \s. It has now been removed in PCRE. This means it isn't recognized as
+ whitespace in /x regexes too, which is the same as Perl. Note that the POSIX
+ class [:space:] *does* include VT, thereby creating a mess.
+. Added the class [:blank:] (a GNU extension from Perl 5.8) to match only
+ space and tab.
+. Perl 5.005 was a long time ago. It's time to amalgamate the tests that use
+ its new features into the main test script, reducing the number of scripts.
+. Perl 5.8 has changed the meaning of patterns like /a(?i)b/. Earlier versions
+ were backward compatible, and made the (?i) apply to the whole pattern, as if
+ /i were given. Now it behaves more logically, and applies the option setting
+ only to what follows. PCRE has been changed to follow suit. However, if it
+ finds options settings right at the start of the pattern, it extracts them into
+ the global options, as before. Thus, they show up in the info data.
+. Added support for the \Q...\E escape sequence. Characters in between are
+ treated as literals. This is slightly different from Perl in that $ and @ are
+ also handled as literals inside the quotes. In Perl, they will cause variable
+ interpolation. Note the following examples:
+     Pattern            PCRE matches      Perl matches
+     \Qabc$xyz\E        abc$xyz           abc followed by the contents of $xyz
+     \Qabc\$xyz\E       abc\$xyz          abc\$xyz
+     \Qabc\E\$\Qxyz\E   abc$xyz           abc$xyz
+ For compatibility with Perl, \Q...\E sequences are recognized inside character
+ classes as well as outside them.
+. Re-organized 3 code statements in pcretest to avoid "overflow in
+ floating-point constant arithmetic" warnings from a Microsoft compiler. Added a
+ (size_t) cast to one statement in pcretest and one in pcreposix to avoid
+ signed/unsigned warnings.
+. SunOS4 doesn't have strtoul(). This was used only for unpicking the -o
+ option for pcretest, so I've replaced it by a simple function that does just
+ that job.
+. pcregrep was ending with code 0 instead of 2 for the commands "pcregrep" or
+ "pcregrep -".
+. Added "possessive quantifiers" ?+, *+, ++, and {,}+ which come from Sun's
+ Java package. This provides some syntactic sugar for simple cases of what my
+ documentation calls "once-only subpatterns". A pattern such as x*+ is the same
+ as (?>x*). In other words, if what is inside (?>...) is just a single repeated
+ item, you can use this simplified notation. Note that only makes sense with
+ greedy quantifiers. Consequently, the use of the possessive quantifier forces
+ greediness, whatever the setting of the PCRE_UNGREEDY option.
+. A change of greediness default within a pattern was not taking effect at
+ the current level for patterns like /(b+(?U)a+)/. It did apply to parenthesized
+ subpatterns that followed. Patterns like /b+(?U)a+/ worked because the option
+ was abstracted outside.
+. PCRE now supports the \G assertion. It is true when the current matching
+ position is at the start point of the match. This differs from \A when the
+ starting offset is non-zero. Used with the /g option of pcretest (or similar
+ code), it works in the same way as it does for Perl's /g option. If all
+ alternatives of a regex begin with \G, the expression is anchored to the start
+ match position, and the "anchored" flag is set in the compiled expression.
+. Some bugs concerning the handling of certain option changes within patterns
+ have been fixed. These applied to options other than (?ims). For example,
+ "a(?x: b c )d" did not match "XabcdY" but did match "Xa b c dY". It should have
+ been the other way round. Some of this was related to change 7 above.
+. PCRE now gives errors for /[.x.]/ and /[=x=]/ as unsupported POSIX
+ features, as Perl does. Previously, PCRE gave the warnings only for /[[.x.]]/
+ and /[[=x=]]/. PCRE now also gives an error for /[:name:]/ because it supports
+ POSIX classes only within a class (e.g. /[[:alpha:]]/).
+. Added support for Perl's \C escape. This matches one byte, even in UTF8
+ mode. Unlike ".", it always matches newline, whatever the setting of
+ PCRE_DOTALL. However, PCRE does not permit \C to appear in lookbehind
+ assertions. Perl allows it, but it doesn't (in general) work because it can't
+ calculate the length of the lookbehind. At least, that's the case for Perl
+.8.0 - I've been told they are going to document that it doesn't work in
+ future.
+. Added an error diagnosis for escapes that PCRE does not support: these are
+ \L, \l, \N, \P, \p, \U, \u, and \X.
+. Although correctly diagnosing a missing ']' in a character class, PCRE was
+ reading past the end of the pattern in cases such as /[abcd/.
+. PCRE was getting more memory than necessary for patterns with classes that
+ contained both POSIX named classes and other characters, e.g. /[[:space:]abc/.
+. Added some code, conditional on #ifdef VPCOMPAT, to make life easier for
+ compiling PCRE for use with Virtual Pascal.
+. Small fix to the Makefile to make it work properly if the build is done
+ outside the source tree.
+. Added a new extension: a condition to go with recursion. If a conditional
+ subpattern starts with (?(R) the "true" branch is used if recursion has
+ happened, whereas the "false" branch is used only at the top level.
+. When there was a very long string of literal characters (over 255 bytes
+ without UTF support, over 250 bytes with UTF support), the computation of how
+ much memory was required could be incorrect, leading to segfaults or other
+ strange effects.
+. PCRE was incorrectly assuming anchoring (either to start of subject or to
+ start of line for a non-DOTALL pattern) when a pattern started with (.*) and
+ there was a subsequent back reference to those brackets. This meant that, for
+ example, /(.*)\d+\1/ failed to match "abc123bc". Unfortunately, it isn't
+ possible to check for precisely this case. All we can do is abandon the
+ optimization if .* occurs inside capturing brackets when there are any back
+ references whatsoever. (See below for a better fix that came later.)
+. The handling of the optimization for finding the first character of a
+ non-anchored pattern, and for finding a character that is required later in the
+ match were failing in some cases. This didn't break the matching; it just
+ failed to optimize when it could. The way this is done has been re-implemented.
+. Fixed typo in error message for invalid (?R item (it said "(?p").
+. Added a new feature that provides some of the functionality that Perl
+ provides with (?{...}). The facility is termed a "callout". The way it is done
+ in PCRE is for the caller to provide an optional function, by setting
+ pcre_callout to its entry point. Like pcre_malloc and pcre_free, this is a
+ global variable. By default it is unset, which disables all calling out. To get
+ the function called, the regex must include (?C) at appropriate points. This
+ is, in fact, equivalent to (?C0), and any number <= 255 may be given with (?C).
+ This provides a means of identifying different callout points. When PCRE
+ reaches such a point in the regex, if pcre_callout has been set, the external
+ function is called. It is provided with data in a structure called
+ pcre_callout_block, which is defined in pcre.h. If the function returns 0,
+ matching continues; if it returns a non-zero value, the match at the current
+ point fails. However, backtracking will occur if possible. [This was changed
+ later and other features added - see item 49 below.]
+. pcretest is upgraded to test the callout functionality. It provides a
+ callout function that displays information. By default, it shows the start of
+ the match and the current position in the text. There are some new data escapes
+ to vary what happens:
+     \C+         in addition, show current contents of captured substrings
+     \C-         do not supply a callout function
+     \C!n        return 1 when callout number n is reached
+     \C!n!m      return 1 when callout number n is reached for the mth time
+. If pcregrep was called with the -l option and just a single file name, it
+ output "<stdin>" if a match was found, instead of the file name.
+. Improve the efficiency of the POSIX API to PCRE. If the number of capturing
+ slots is less than POSIX_MALLOC_THRESHOLD, use a block on the stack to pass to
+ pcre_exec(). This saves a malloc/free per call. The default value of
+ POSIX_MALLOC_THRESHOLD is 10; it can be changed by --with-posix-malloc-threshold
+ when configuring.
+. The default maximum size of a compiled pattern is 64K. There have been a
+ few cases of people hitting this limit. The code now uses macros to handle the
+ storing of links as offsets within the compiled pattern. It defaults to 2-byte
+ links, but this can be changed to 3 or 4 bytes by --with-link-size when
+ configuring. Tests 2 and 5 work only with 2-byte links because they output
+ debugging information about compiled patterns.
+. Internal code re-arrangements:
+ (a) Moved the debugging function for printing out a compiled regex into
+     its own source file (printint.c) and used #include to pull it into
+     pcretest.c and, when DEBUG is defined, into pcre.c, instead of having two
+     separate copies.
+ (b) Defined the list of op-code names for debugging as a macro in
+     internal.h so that it is next to the definition of the opcodes.
+ (c) Defined a table of op-code lengths for simpler skipping along compiled
+     code. This is again a macro in internal.h so that it is next to the
+     definition of the opcodes.
+. Added support for recursive calls to individual subpatterns, along the
+ lines of Robin Houston's patch (but implemented somewhat differently).
+. Further mods to the Makefile to help Win32. Also, added code to pcregrep to
+ allow it to read and process whole directories in Win32. This code was
+ contributed by Lionel Fourquaux; it has not been tested by me.
+. Added support for named subpatterns. The Python syntax (?P<name>...) is
+ used to name a group. Names consist of alphanumerics and underscores, and must
+ be unique. Back references use the syntax (?P=name) and recursive calls use
+ (?P>name) which is a PCRE extension to the Python extension. Groups still have
+ numbers. The function pcre_fullinfo() can be used after compilation to extract
+ a name/number map. There are three relevant calls:
+   PCRE_INFO_NAMEENTRYSIZE        yields the size of each entry in the map
+   PCRE_INFO_NAMECOUNT            yields the number of entries
+   PCRE_INFO_NAMETABLE            yields a pointer to the map.
+ The map is a vector of fixed-size entries. The size of each entry depends on
+ the length of the longest name used. The first two bytes of each entry are the
+ group number, most significant byte first. There follows the corresponding
+ name, zero terminated. The names are in alphabetical order.
+. Make the maximum literal string in the compiled code 250 for the non-UTF-8
+ case instead of 255. Making it the same both with and without UTF-8 support
+ means that the same test output works with both.
+. There was a case of malloc(0) in the POSIX testing code in pcretest. Avoid
+ calling malloc() with a zero argument.
+. Change 25 above had to resort to a heavy-handed test for the .* anchoring
+ optimization. I've improved things by keeping a bitmap of backreferences with
+ numbers 1-31 so that if .* occurs inside capturing brackets that are not in
+ fact referenced, the optimization can be applied. It is unlikely that a
+ relevant occurrence of .* (i.e. one which might indicate anchoring or forcing
+ the match to follow \n) will appear inside brackets with a number greater than
+, but if it does, any back reference > 31 suppresses the optimization.
+. Added a new compile-time option PCRE_NO_AUTO_CAPTURE. This has the effect
+ of disabling numbered capturing parentheses. Any opening parenthesis that is
+ not followed by ? behaves as if it were followed by ?: but named parentheses
+ can still be used for capturing (and they will acquire numbers in the usual
+ way).
+. Redesigned the return codes from the match() function into yes/no/error so
+ that errors can be passed back from deep inside the nested calls. A malloc
+ failure while inside a recursive subpattern call now causes the
+ PCRE_ERROR_NOMEMORY return instead of quietly going wrong.
+. It is now possible to set a limit on the number of times the match()
+ function is called in a call to pcre_exec(). This facility makes it possible to
+ limit the amount of recursion and backtracking, though not in a directly
+ obvious way, because the match() function is used in a number of different
+ circumstances. The count starts from zero for each position in the subject
+ string (for non-anchored patterns). The default limit is, for compatibility, a
+ large number, namely 10 000 000. You can change this in two ways:
+ (a) When configuring PCRE before making, you can use --with-match-limit=n
+     to set a default value for the compiled library.
+ (b) For each call to pcre_exec(), you can pass a pcre_extra block in which
+     a different value is set. See 45 below.
+ If the limit is exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT.
+. Added a new function pcre_config(int, void *) to enable run-time extraction
+ of things that can be changed at compile time. The first argument specifies
+ what is wanted and the second points to where the information is to be placed.
+ The current list of available information is:
+   PCRE_CONFIG_UTF8
+ The output is an integer that is set to one if UTF-8 support is available;
+ otherwise it is set to zero.
+   PCRE_CONFIG_NEWLINE
+ The output is an integer that it set to the value of the code that is used for
+ newline. It is either LF (10) or CR (13).
+   PCRE_CONFIG_LINK_SIZE
+ The output is an integer that contains the number of bytes used for internal
+ linkage in compiled expressions. The value is 2, 3, or 4. See item 32 above.
+   PCRE_CONFIG_POSIX_MALLOC_THRESHOLD
+ The output is an integer that contains the threshold above which the POSIX
+ interface uses malloc() for output vectors. See item 31 above.
+   PCRE_CONFIG_MATCH_LIMIT
+ The output is an unsigned integer that contains the default limit of the number
+ of match() calls in a pcre_exec() execution. See 42 above.
+. pcretest has been upgraded by the addition of the -C option. This causes it
+ to extract all the available output from the new pcre_config() function, and to
+ output it. The program then exits immediately.
+. A need has arisen to pass over additional data with calls to pcre_exec() in
+ order to support additional features. One way would have been to define
+ pcre_exec2() (for example) with extra arguments, but this would not have been
+ extensible, and would also have required all calls to the original function to
+ be mapped to the new one. Instead, I have chosen to extend the mechanism that
+ is used for passing in "extra" data from pcre_study().
+ The pcre_extra structure is now exposed and defined in pcre.h. It currently
+ contains the following fields:
+   flags         a bitmap indicating which of the following fields are set
+   study_data    opaque data from pcre_study()
+   match_limit   a way of specifying a limit on match() calls for a specific
+                   call to pcre_exec()
+   callout_data  data for callouts (see 49 below)
+ The flag bits are also defined in pcre.h, and are
+   PCRE_EXTRA_STUDY_DATA
+   PCRE_EXTRA_MATCH_LIMIT
+   PCRE_EXTRA_CALLOUT_DATA
+ The pcre_study() function now returns one of these new pcre_extra blocks, with
+ the actual study data pointed to by the study_data field, and the
+ PCRE_EXTRA_STUDY_DATA flag set. This can be passed directly to pcre_exec() as
+ before. That is, this change is entirely upwards-compatible and requires no
+ change to existing code.
+ If you want to pass in additional data to pcre_exec(), you can either place it
+ in a pcre_extra block provided by pcre_study(), or create your own pcre_extra
+ block.
+. pcretest has been extended to test the PCRE_EXTRA_MATCH_LIMIT feature. If a
+ data string contains the escape sequence \M, pcretest calls pcre_exec() several
+ times with different match limits, until it finds the minimum value needed for
+ pcre_exec() to complete. The value is then output. This can be instructive; for
+ most simple matches the number is quite small, but for pathological cases it
+ gets very large very quickly.
+. There's a new option for pcre_fullinfo() called PCRE_INFO_STUDYSIZE. It
+ returns the size of the data block pointed to by the study_data field in a
+ pcre_extra block, that is, the value that was passed as the argument to
+ pcre_malloc() when PCRE was getting memory in which to place the information
+ created by pcre_study(). The fourth argument should point to a size_t variable.
+ pcretest has been extended so that this information is shown after a successful
+ pcre_study() call when information about the compiled regex is being displayed.
+. Cosmetic change to Makefile: there's no need to have / after $(DESTDIR)
+ because what follows is always an absolute path. (Later: it turns out that this
+ is more than cosmetic for MinGW, because it doesn't like empty path
+ components.)
+. Some changes have been made to the callout feature (see 28 above):
+ (i)  A callout function now has three choices for what it returns:
+ =>  success, carry on matching
+      > 0  =>  failure at this point, but backtrack if possible
+      < 0  =>  serious error, return this value from pcre_exec()
+      Negative values should normally be chosen from the set of PCRE_ERROR_xxx
+      values. In particular, returning PCRE_ERROR_NOMATCH forces a standard
+      "match failed" error. The error number PCRE_ERROR_CALLOUT is reserved for
+      use by callout functions. It will never be used by PCRE itself.
+ (ii) The pcre_extra structure (see 45 above) has a void * field called
+      callout_data, with corresponding flag bit PCRE_EXTRA_CALLOUT_DATA. The
+      pcre_callout_block structure has a field of the same name. The contents of
+      the field passed in the pcre_extra structure are passed to the callout
+      function in the corresponding field in the callout block. This makes it
+      easier to use the same callout-containing regex from multiple threads. For
+      testing, the pcretest program has a new data escape
+        \C*n        pass the number n (may be negative) as callout_data
+      If the callout function in pcretest receives a non-zero value as
+      callout_data, it returns that value.
+. Makefile wasn't handling CFLAGS properly when compiling dftables. Also,
+ there were some redundant $(CFLAGS) in commands that are now specified as
+ $(LINK), which already includes $(CFLAGS).
+. Extensions to UTF-8 support are listed below. These all apply when (a) PCRE
+ has been compiled with UTF-8 support *and* pcre_compile() has been compiled
+ with the PCRE_UTF8 flag. Patterns that are compiled without that flag assume
+ one-byte characters throughout. Note that case-insensitive matching applies
+ only to characters whose values are less than 256. PCRE doesn't support the
+ notion of cases for higher-valued characters.
+ (i)   A character class whose characters are all within 0-255 is handled as
+       a bit map, and the map is inverted for negative classes. Previously, a
+       character > 255 always failed to match such a class; however it should
+       match if the class was a negative one (e.g. [^ab]). This has been fixed.
+ (ii)  A negated character class with a single character < 255 is coded as
+       "not this character" (OP_NOT). This wasn't working properly when the test
+       character was multibyte, either singly or repeated.
+ (iii) Repeats of multibyte characters are now handled correctly in UTF-8
+       mode, for example: \x{100}{2,3}.
+ (iv)  The character escapes \b, \B, \d, \D, \s, \S, \w, and \W (either
+       singly or repeated) now correctly test multibyte characters. However,
+       PCRE doesn't recognize any characters with values greater than 255 as
+       digits, spaces, or word characters. Such characters always match \D, \S,
+       and \W, and never match \d, \s, or \w.
+ (v)   Classes may now contain characters and character ranges with values
+       greater than 255. For example: [ab\x{100}-\x{400}].
+ (vi)  pcregrep now has a --utf-8 option (synonym -u) which makes it call
+       PCRE in UTF-8 mode.
+. The info request value PCRE_INFO_FIRSTCHAR has been renamed
+ PCRE_INFO_FIRSTBYTE because it is a byte value. However, the old name is
+ retained for backwards compatibility. (Note that LASTLITERAL is also a byte
+ value.)
+. The single man page has become too large. I have therefore split it up into
+ a number of separate man pages. These also give rise to individual HTML pages;
+ these are now put in a separate directory, and there is an index.html page that
+ lists them all. Some hyperlinking between the pages has been installed.
+. Added convenience functions for handling named capturing parentheses.
+. Unknown escapes inside character classes (e.g. [\M]) and escapes that
+ aren't interpreted therein (e.g. [\C]) are literals in Perl. This is now also
+ true in PCRE, except when the PCRE_EXTENDED option is set, in which case they
+ are faulted.
+. Introduced HOST_CC and HOST_CFLAGS which can be set in the environment when
+ calling configure. These values are used when compiling the dftables.c program
+ which is run to generate the source of the default character tables. They
+ default to the values of CC and CFLAGS. If you are cross-compiling PCRE,
+ you will need to set these values.
+. Updated the building process for Windows DLL, as provided by Fred Cox.
+ Version 3.9 02-Jan-02
+ ---------------------
+. A bit of extraneous text had somehow crept into the pcregrep documentation.
+. If --disable-static was given, the building process failed when trying to
+ build pcretest and pcregrep. (For some reason it was using libtool to compile
+ them, which is not right, as they aren't part of the library.)
+ Version 3.8 18-Dec-01
+ ---------------------
+. The experimental UTF-8 code was completely screwed up. It was packing the
+ bytes in the wrong order. How dumb can you get?
+ Version 3.7 29-Oct-01
+ ---------------------
+. In updating pcretest to check change 1 of version 3.6, I screwed up.
+ This caused pcretest, when used on the test data, to segfault. Unfortunately,
+ this didn't happen under Solaris 8, where I normally test things.
+. The Makefile had to be changed to make it work on BSD systems, where 'make'
+ doesn't seem to recognize that ./xxx and xxx are the same file. (This entry
+ isn't in ChangeLog distributed with 3.7 because I forgot when I hastily made
+ this fix an hour or so after the initial 3.7 release.)
+ Version 3.6 23-Oct-01
+ ---------------------
+. Crashed with /(sens|respons)e and \1ibility/ and "sense and sensibility" if
+ offsets passed as NULL with zero offset count.
+. The config.guess and config.sub files had not been updated when I moved to
+ the latest autoconf.
+ Version 3.5 15-Aug-01
+ ---------------------
+. Added some missing #if !defined NOPOSIX conditionals in pcretest.c that
+ had been forgotten.
+. By using declared but undefined structures, we can avoid using "void"
+ definitions in pcre.h while keeping the internal definitions of the structures
+ private.
+. The distribution is now built using autoconf 2.50 and libtool 1.4. From a
+ user point of view, this means that both static and shared libraries are built
+ by default, but this can be individually controlled. More of the work of
+ handling this static/shared cases is now inside libtool instead of PCRE's make
+ file.
+. The pcretest utility is now installed along with pcregrep because it is
+ useful for users (to test regexs) and by doing this, it automatically gets
+ relinked by libtool. The documentation has been turned into a man page, so
+ there are now .1, .txt, and .html versions in /doc.
+. Upgrades to pcregrep:
+    (i)   Added long-form option names like gnu grep.
+    (ii)  Added --help to list all options with an explanatory phrase.
+    (iii) Added -r, --recursive to recurse into sub-directories.
+    (iv)  Added -f, --file to read patterns from a file.
+. pcre_exec() was referring to its "code" argument before testing that
+ argument for NULL (and giving an error if it was NULL).
+. Upgraded Makefile.in to allow for compiling in a different directory from
+ the source directory.
+. Tiny buglet in pcretest: when pcre_fullinfo() was called to retrieve the
+ options bits, the pointer it was passed was to an int instead of to an unsigned
+ long int. This mattered only on 64-bit systems.
+. Fixed typo (3.4/1) in pcre.h again. Sigh. I had changed pcre.h (which is
+ generated) instead of pcre.in, which it its source. Also made the same change
+ in several of the .c files.
+. A new release of gcc defines printf() as a macro, which broke pcretest
+ because it had an ifdef in the middle of a string argument for printf(). Fixed
+ by using separate calls to printf().
+. Added --enable-newline-is-cr and --enable-newline-is-lf to the configure
+ script, to force use of CR or LF instead of \n in the source. On non-Unix
+ systems, the value can be set in config.h.
+. The limit of 200 on non-capturing parentheses is a _nesting_ limit, not an
+ absolute limit. Changed the text of the error message to make this clear, and
+ likewise updated the man page.
+. The limit of 99 on the number of capturing subpatterns has been removed.
+ The new limit is 65535, which I hope will not be a "real" limit.
+ Version 3.4 22-Aug-00
+ ---------------------
+. Fixed typo in pcre.h: unsigned const char * changed to const unsigned char *.
+. Diagnose condition (?(0) as an error instead of crashing on matching.
  Version 3.3 01-Aug-00
  ---------------------

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