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    1 ChangeLog for PCRE
    2 ------------------
    3 
    4 Version 7.0 19-Dec-06
    5 ---------------------
    6 
    7  1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
    8     moving to gcc 4.1.1.
    9 
   10  2. The -S option for pcretest uses setrlimit(); I had omitted to #include
   11     sys/time.h, which is documented as needed for this function. It doesn't
   12     seem to matter on Linux, but it showed up on some releases of OS X.
   13 
   14  3. It seems that there are systems where bytes whose values are greater than
   15     127 match isprint() in the "C" locale. The "C" locale should be the
   16     default when a C program starts up. In most systems, only ASCII printing
   17     characters match isprint(). This difference caused the output from pcretest
   18     to vary, making some of the tests fail. I have changed pcretest so that:
   19 
   20     (a) When it is outputting text in the compiled version of a pattern, bytes
   21         other than 32-126 are always shown as hex escapes.
   22 
   23     (b) When it is outputting text that is a matched part of a subject string,
   24         it does the same, unless a different locale has been set for the match
   25         (using the /L modifier). In this case, it uses isprint() to decide.
   26 
   27  4. Fixed a major bug that caused incorrect computation of the amount of memory
   28     required for a compiled pattern when options that changed within the
   29     pattern affected the logic of the preliminary scan that determines the
   30     length. The relevant options are -x, and -i in UTF-8 mode. The result was
   31     that the computed length was too small. The symptoms of this bug were
   32     either the PCRE error "internal error: code overflow" from pcre_compile(),
   33     or a glibc crash with a message such as "pcretest: free(): invalid next
   34     size (fast)". Examples of patterns that provoked this bug (shown in
   35     pcretest format) are:
   36 
   37       /(?-x: )/x
   38       /(?x)(?-x: \s*#\s*)/
   39       /((?i)[\x{c0}])/8
   40       /(?i:[\x{c0}])/8
   41 
   42     HOWEVER: Change 17 below makes this fix obsolete as the memory computation
   43     is now done differently.
   44 
   45  5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
   46     wrapper classes; (b) implement a new function in the C++ scanner that is
   47     more efficient than the old way of doing things because it avoids levels of
   48     recursion in the regex matching; (c) add a paragraph to the documentation
   49     for the FullMatch() function.
   50 
   51  6. The escape sequence \n was being treated as whatever was defined as
   52     "newline". Not only was this contrary to the documentation, which states
   53     that \n is character 10 (hex 0A), but it also went horribly wrong when
   54     "newline" was defined as CRLF. This has been fixed.
   55 
   56  7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
   57     was being set to -1 for the "end of line" case (supposedly a value that no
   58     character can have). Though this value is never used (the check for end of
   59     line is "zero bytes in current character"), it caused compiler complaints.
   60     I've changed it to 0xffffffff.
   61 
   62  8. In pcre_version.c, the version string was being built by a sequence of
   63     C macros that, in the event of PCRE_PRERELEASE being defined as an empty
   64     string (as it is for production releases) called a macro with an empty
   65     argument. The C standard says the result of this is undefined. The gcc
   66     compiler treats it as an empty string (which was what was wanted) but it is
   67     reported that Visual C gives an error. The source has been hacked around to
   68     avoid this problem.
   69 
   70  9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
   71     builds of pcretest, and changed the call to _setmode() to use _O_BINARY
   72     instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
   73     of them did).
   74 
   75 10. Originally, pcretest opened its input and output without "b"; then I was
   76     told that "b" was needed in some environments, so it was added for release
   77     5.0 to both the input and output. (It makes no difference on Unix-like
   78     systems.) Later I was told that it is wrong for the input on Windows. I've
   79     now abstracted the modes into two macros, to make it easier to fiddle with
   80     them, and removed "b" from the input mode under Windows.
   81 
   82 11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
   83 
   84 12. Added -help and --help to pcretest as an official way of being reminded
   85     of the options.
   86 
   87 13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
   88     and pcrecpp.cc because they annoy compilers at high warning levels.
   89 
   90 14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
   91 
   92 15. Fixed an occurrence of == in configure.ac that should have been = (shell
   93     scripts are not C programs :-) and which was not noticed because it works
   94     on Linux.
   95 
   96 16. pcretest is supposed to handle any length of pattern and data line (as one
   97     line or as a continued sequence of lines) by extending its input buffer if
   98     necessary. This feature was broken for very long pattern lines, leading to
   99     a string of junk being passed to pcre_compile() if the pattern was longer
  100     than about 50K.
  101 
  102 17. I have done a major re-factoring of the way pcre_compile() computes the
  103     amount of memory needed for a compiled pattern. Previously, there was code
  104     that made a preliminary scan of the pattern in order to do this. That was
  105     OK when PCRE was new, but as the facilities have expanded, it has become
  106     harder and harder to keep it in step with the real compile phase, and there
  107     have been a number of bugs (see for example, 4 above). I have now found a
  108     cunning way of running the real compile function in a "fake" mode that
  109     enables it to compute how much memory it would need, while actually only
  110     ever using a few hundred bytes of working memory and without too many
  111     tests of the mode. This should make future maintenance and development
  112     easier. A side effect of this work is that the limit of 200 on the nesting
  113     depth of parentheses has been removed (though this was never a serious
  114     limitation, I suspect). However, there is a downside: pcre_compile() now
  115     runs more slowly than before (30% or more, depending on the pattern). I
  116     hope this isn't a big issue. There is no effect on runtime performance.
  117 
  118 18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
  119     newline (only possible for the last line of a file) and it was a
  120     pattern that set a locale (followed by /Lsomething), pcretest crashed.
  121 
  122 19. Added additional timing features to pcretest. (1) The -tm option now times
  123     matching only, not compiling. (2) Both -t and -tm can be followed, as a
  124     separate command line item, by a number that specifies the number of
  125     repeats to use when timing. The default is 50000; this gives better
  126     precision, but takes uncomfortably long for very large patterns.
  127 
  128 20. Extended pcre_study() to be more clever in cases where a branch of a
  129     subpattern has no definite first character. For example, (a*|b*)[cd] would
  130     previously give no result from pcre_study(). Now it recognizes that the
  131     first character must be a, b, c, or d.
  132 
  133 21. There was an incorrect error "recursive call could loop indefinitely" if
  134     a subpattern (or the entire pattern) that was being tested for matching an
  135     empty string contained only one non-empty item after a nested subpattern.
  136     For example, the pattern (?>\x{100}*)\d(?R) provoked this error
  137     incorrectly, because the \d was being skipped in the check.
  138 
  139 22. The pcretest program now has a new pattern option /B and a command line
  140     option -b, which is equivalent to adding /B to every pattern. This causes
  141     it to show the compiled bytecode, without the additional information that
  142     -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
  143     is the same as /B/I).
  144 
  145 23. A new optimization is now able automatically to treat some sequences such
  146     as a*b as a*+b. More specifically, if something simple (such as a character
  147     or a simple class like \d) has an unlimited quantifier, and is followed by
  148     something that cannot possibly match the quantified thing, the quantifier
  149     is automatically "possessified".
  150 
  151 24. A recursive reference to a subpattern whose number was greater than 39
  152     went wrong under certain circumstances in UTF-8 mode. This bug could also
  153     have affected the operation of pcre_study().
  154 
  155 25. Realized that a little bit of performance could be had by replacing
  156     (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
  157 
  158 26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
  159 
  160 27. Possessive quantifiers such as a++ were previously implemented by turning
  161     them into atomic groups such as ($>a+). Now they have their own opcodes,
  162     which improves performance. This includes the automatically created ones
  163     from 23 above.
  164 
  165 28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
  166     lookahead was broken if it was not anchored. PCRE was mistakenly expecting
  167     the first matched character to be a colon. This applied both to named and
  168     numbered groups.
  169 
  170 29. The ucpinternal.h header file was missing its idempotency #ifdef.
  171 
  172 30. I was sent a "project" file called libpcre.a.dev which I understand makes
  173     building PCRE on Windows easier, so I have included it in the distribution.
  174 
  175 31. There is now a check in pcretest against a ridiculously large number being
  176     returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
  177     loop, the loop is abandoned.
  178 
  179 32. Forward references to subpatterns in conditions such as (?(2)...) where
  180     subpattern 2 is defined later cause pcre_compile() to search forwards in
  181     the pattern for the relevant set of parentheses. This search went wrong
  182     when there were unescaped parentheses in a character class, parentheses
  183     escaped with \Q...\E, or parentheses in a #-comment in /x mode.
  184 
  185 33. "Subroutine" calls and backreferences were previously restricted to
  186     referencing subpatterns earlier in the regex. This restriction has now
  187     been removed.
  188 
  189 34. Added a number of extra features that are going to be in Perl 5.10. On the
  190     whole, these are just syntactic alternatives for features that PCRE had
  191     previously implemented using the Python syntax or my own invention. The
  192     other formats are all retained for compatibility.
  193 
  194     (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
  195         as (?P<name>...). The new forms, as well as being in Perl 5.10, are
  196         also .NET compatible.
  197 
  198     (b) A recursion or subroutine call to a named group can now be defined as
  199         (?&name) as well as (?P>name).
  200 
  201     (c) A backreference to a named group can now be defined as \k<name> or
  202         \k'name' as well as (?P=name). The new forms, as well as being in Perl
  203         5.10, are also .NET compatible.
  204 
  205     (d) A conditional reference to a named group can now use the syntax
  206         (?(<name>) or (?('name') as well as (?(name).
  207 
  208     (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
  209         groups (named and numbered) that are never evaluated inline, but can be
  210         called as "subroutines" from elsewhere. In effect, the DEFINE condition
  211         is always false. There may be only one alternative in such a group.
  212 
  213     (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
  214         as the simple (?(R). The condition is true only if the most recent
  215         recursion is that of the given number or name. It does not search out
  216         through the entire recursion stack.
  217 
  218     (g) The escape \gN or \g{N} has been added, where N is a positive or
  219         negative number, specifying an absolute or relative reference.
  220 
  221 35. Tidied to get rid of some further signed/unsigned compiler warnings and
  222     some "unreachable code" warnings.
  223 
  224 36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
  225     things, this adds five new scripts.
  226 
  227 37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
  228     There were also incompatibilities regarding the handling of \Q..\E inside
  229     character classes, for example with patterns like [\Qa\E-\Qz\E] where the
  230     hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
  231 
  232 38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
  233     matches an empty string, and forcibly breaks the loop. There were bugs in
  234     this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
  235     against  aaaa  the result was just "a" rather than "aaaa", for example. Two
  236     separate and independent bugs (that affected different cases) have been
  237     fixed.
  238 
  239 39. Refactored the code to abolish the use of different opcodes for small
  240     capturing bracket numbers. This is a tidy that I avoided doing when I
  241     removed the limit on the number of capturing brackets for 3.5 back in 2001.
  242     The new approach is not only tidier, it makes it possible to reduce the
  243     memory needed to fix the previous bug (38).
  244 
  245 40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
  246     sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
  247     processing dot, circumflex, or dollar metacharacters, or #-comments in /x
  248     mode.
  249 
  250 41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
  251     report.
  252 
  253 42. Applied patch, originally from Ari Pollak, modified by Google, to allow
  254     copy construction and assignment in the C++ wrapper.
  255 
  256 43. Updated pcregrep to support "--newline=any". In the process, I fixed a
  257     couple of bugs that could have given wrong results in the "--newline=crlf"
  258     case.
  259 
  260 44. Added a number of casts and did some reorganization of signed/unsigned int
  261     variables following suggestions from Dair Grant. Also renamed the variable
  262     "this" as "item" because it is a C++ keyword.
  263 
  264 45. Arranged for dftables to add
  265 
  266       #include "pcre_internal.h"
  267 
  268     to pcre_chartables.c because without it, gcc 4.x may remove the array
  269     definition from the final binary if PCRE is built into a static library and
  270     dead code stripping is activated.
  271 
  272 46. For an unanchored pattern, if a match attempt fails at the start of a
  273     newline sequence, and the newline setting is CRLF or ANY, and the next two
  274     characters are CRLF, advance by two characters instead of one.
  275 
  276 
  277 Version 6.7 04-Jul-06
  278 ---------------------
  279 
  280  1. In order to handle tests when input lines are enormously long, pcretest has
  281     been re-factored so that it automatically extends its buffers when
  282     necessary. The code is crude, but this _is_ just a test program. The
  283     default size has been increased from 32K to 50K.
  284 
  285  2. The code in pcre_study() was using the value of the re argument before
  286     testing it for NULL. (Of course, in any sensible call of the function, it
  287     won't be NULL.)
  288 
  289  3. The memmove() emulation function in pcre_internal.h, which is used on
  290     systems that lack both memmove() and bcopy() - that is, hardly ever -
  291     was missing a "static" storage class specifier.
  292 
  293  4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
  294     containing an extended class (one that cannot be represented by a bitmap
  295     because it contains high-valued characters or Unicode property items, e.g.
  296     [\pZ]). Almost always one would set UTF-8 mode when processing such a
  297     pattern, but PCRE should not loop if you do not (it no longer does).
  298     [Detail: two cases were found: (a) a repeated subpattern containing an
  299     extended class; (b) a recursive reference to a subpattern that followed a
  300     previous extended class. It wasn't skipping over the extended class
  301     correctly when UTF-8 mode was not set.]
  302 
  303  5. A negated single-character class was not being recognized as fixed-length
  304     in lookbehind assertions such as (?<=[^f]), leading to an incorrect
  305     compile error "lookbehind assertion is not fixed length".
  306 
  307  6. The RunPerlTest auxiliary script was showing an unexpected difference
  308     between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
  309     write a Perl script that can interpret lines of an input file either as
  310     byte characters or as UTF-8, which is what "perltest" was being required to
  311     do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
  312     can't do is switch easily at run time between having the "use utf8;" pragma
  313     or not. In the end, I fudged it by using the RunPerlTest script to insert
  314     "use utf8;" explicitly for the UTF-8 tests.
  315 
  316  7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
  317     the end of the subject string, contrary to the documentation and to what
  318     Perl does. This was true of both matching functions. Now it matches only at
  319     the start of the subject and immediately after *internal* newlines.
  320 
  321  8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
  322     a pointer to an int instead of a pointer to an unsigned long int. This
  323     caused problems on 64-bit systems.
  324 
  325  9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
  326     instance of the 'standard' template library not being so standard".
  327 
  328 10. There was no check on the number of named subpatterns nor the maximum
  329     length of a subpattern name. The product of these values is used to compute
  330     the size of the memory block for a compiled pattern. By supplying a very
  331     long subpattern name and a large number of named subpatterns, the size
  332     computation could be caused to overflow. This is now prevented by limiting
  333     the length of names to 32 characters, and the number of named subpatterns
  334     to 10,000.
  335 
  336 11. Subpatterns that are repeated with specific counts have to be replicated in
  337     the compiled pattern. The size of memory for this was computed from the
  338     length of the subpattern and the repeat count. The latter is limited to
  339     65535, but there was no limit on the former, meaning that integer overflow
  340     could in principle occur. The compiled length of a repeated subpattern is
  341     now limited to 30,000 bytes in order to prevent this.
  342 
  343 12. Added the optional facility to have named substrings with the same name.
  344 
  345 13. Added the ability to use a named substring as a condition, using the
  346     Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
  347     are numbers (not recommended). Forward references are permitted.
  348 
  349 14. Added forward references in named backreferences (if you see what I mean).
  350 
  351 15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
  352     pattern could run off the end of the subject. For example, the pattern
  353     "(?s)(.{1,5})"8 did this with the subject "ab".
  354 
  355 16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
  356     PCRE_CASELESS was set when matching characters that were quantified with ?
  357     or *.
  358 
  359 17. A character class other than a single negated character that had a minimum
  360     but no maximum quantifier - for example [ab]{6,} - was not handled
  361     correctly by pce_dfa_exec(). It would match only one character.
  362 
  363 18. A valid (though odd) pattern that looked like a POSIX character
  364     class but used an invalid character after [ (for example [[,abc,]]) caused
  365     pcre_compile() to give the error "Failed: internal error: code overflow" or
  366     in some cases to crash with a glibc free() error. This could even happen if
  367     the pattern terminated after [[ but there just happened to be a sequence of
  368     letters, a binary zero, and a closing ] in the memory that followed.
  369 
  370 19. Perl's treatment of octal escapes in the range \400 to \777 has changed
  371     over the years. Originally (before any Unicode support), just the bottom 8
  372     bits were taken. Thus, for example, \500 really meant \100. Nowadays the
  373     output from "man perlunicode" includes this:
  374 
  375       The regular expression compiler produces polymorphic opcodes.  That
  376       is, the pattern adapts to the data and automatically switches to
  377       the Unicode character scheme when presented with Unicode data--or
  378       instead uses a traditional byte scheme when presented with byte
  379       data.
  380 
  381     Sadly, a wide octal escape does not cause a switch, and in a string with
  382     no other multibyte characters, these octal escapes are treated as before.
  383     Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
  384     /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
  385     Unicode string.
  386 
  387     I have not perpetrated such confusion in PCRE. Up till now, it took just
  388     the bottom 8 bits, as in old Perl. I have now made octal escapes with
  389     values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
  390     translate to the appropriate multibyte character.
  391 
  392 29. Applied some refactoring to reduce the number of warnings from Microsoft
  393     and Borland compilers. This has included removing the fudge introduced
  394     seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
  395     a warning about an unused variable.
  396 
  397 21. PCRE has not included VT (character 0x0b) in the set of whitespace
  398     characters since release 4.0, because Perl (from release 5.004) does not.
  399     [Or at least, is documented not to: some releases seem to be in conflict
  400     with the documentation.] However, when a pattern was studied with
  401     pcre_study() and all its branches started with \s, PCRE still included VT
  402     as a possible starting character. Of course, this did no harm; it just
  403     caused an unnecessary match attempt.
  404 
  405 22. Removed a now-redundant internal flag bit that recorded the fact that case
  406     dependency changed within the pattern. This was once needed for "required
  407     byte" processing, but is no longer used. This recovers a now-scarce options
  408     bit. Also moved the least significant internal flag bit to the most-
  409     significant bit of the word, which was not previously used (hangover from
  410     the days when it was an int rather than a uint) to free up another bit for
  411     the future.
  412 
  413 23. Added support for CRLF line endings as well as CR and LF. As well as the
  414     default being selectable at build time, it can now be changed at runtime
  415     via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
  416     specify that it is scanning data with non-default line endings.
  417 
  418 24. Changed the definition of CXXLINK to make it agree with the definition of
  419     LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
  420 
  421 25. Applied Ian Taylor's patches to avoid using another stack frame for tail
  422     recursions. This makes a big different to stack usage for some patterns.
  423 
  424 26. If a subpattern containing a named recursion or subroutine reference such
  425     as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
  426     the space required for the compiled pattern went wrong and gave too small a
  427     value. Depending on the environment, this could lead to "Failed: internal
  428     error: code overflow at offset 49" or "glibc detected double free or
  429     corruption" errors.
  430 
  431 27. Applied patches from Google (a) to support the new newline modes and (b) to
  432     advance over multibyte UTF-8 characters in GlobalReplace.
  433 
  434 28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
  435     difference for some implementation of PCRE in some Windows version.
  436 
  437 29. Added some extra testing facilities to pcretest:
  438 
  439     \q<number>   in a data line sets the "match limit" value
  440     \Q<number>   in a data line sets the "match recursion limt" value
  441     -S <number>  sets the stack size, where <number> is in megabytes
  442 
  443     The -S option isn't available for Windows.
  444 
  445 
  446 Version 6.6 06-Feb-06
  447 ---------------------
  448 
  449  1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
  450     in pcreposix.h. I have copied the definition from pcre.h.
  451 
  452  2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
  453     because pcre.h is no longer a built file.
  454 
  455  3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
  456     not normally included in the compiled code.
  457 
  458 
  459 Version 6.5 01-Feb-06
  460 ---------------------
  461 
  462  1. When using the partial match feature with pcre_dfa_exec(), it was not
  463     anchoring the second and subsequent partial matches at the new starting
  464     point. This could lead to incorrect results. For example, with the pattern
  465     /1234/, partially matching against "123" and then "a4" gave a match.
  466 
  467  2. Changes to pcregrep:
  468 
  469     (a) All non-match returns from pcre_exec() were being treated as failures
  470         to match the line. Now, unless the error is PCRE_ERROR_NOMATCH, an
  471         error message is output. Some extra information is given for the
  472         PCRE_ERROR_MATCHLIMIT and PCRE_ERROR_RECURSIONLIMIT errors, which are
  473         probably the only errors that are likely to be caused by users (by
  474         specifying a regex that has nested indefinite repeats, for instance).
  475         If there are more than 20 of these errors, pcregrep is abandoned.
  476 
  477     (b) A binary zero was treated as data while matching, but terminated the
  478         output line if it was written out. This has been fixed: binary zeroes
  479         are now no different to any other data bytes.
  480 
  481     (c) Whichever of the LC_ALL or LC_CTYPE environment variables is set is
  482         used to set a locale for matching. The --locale=xxxx long option has
  483         been added (no short equivalent) to specify a locale explicitly on the
  484         pcregrep command, overriding the environment variables.
  485 
  486     (d) When -B was used with -n, some line numbers in the output were one less
  487         than they should have been.
  488 
  489     (e) Added the -o (--only-matching) option.
  490 
  491     (f) If -A or -C was used with -c (count only), some lines of context were
  492         accidentally printed for the final match.
  493 
  494     (g) Added the -H (--with-filename) option.
  495 
  496     (h) The combination of options -rh failed to suppress file names for files
  497         that were found from directory arguments.
  498 
  499     (i) Added the -D (--devices) and -d (--directories) options.
  500 
  501     (j) Added the -F (--fixed-strings) option.
  502 
  503     (k) Allow "-" to be used as a file name for -f as well as for a data file.
  504 
  505     (l) Added the --colo(u)r option.
  506 
  507     (m) Added Jeffrey Friedl's -S testing option, but within #ifdefs so that it
  508         is not present by default.
  509 
  510  3. A nasty bug was discovered in the handling of recursive patterns, that is,
  511     items such as (?R) or (?1), when the recursion could match a number of
  512     alternatives. If it matched one of the alternatives, but subsequently,
  513     outside the recursion, there was a failure, the code tried to back up into
  514     the recursion. However, because of the way PCRE is implemented, this is not
  515     possible, and the result was an incorrect result from the match.
  516 
  517     In order to prevent this happening, the specification of recursion has
  518     been changed so that all such subpatterns are automatically treated as
  519     atomic groups. Thus, for example, (?R) is treated as if it were (?>(?R)).
  520 
  521  4. I had overlooked the fact that, in some locales, there are characters for
  522     which isalpha() is true but neither isupper() nor islower() are true. In
  523     the fr_FR locale, for instance, the \xAA and \xBA characters (ordmasculine
  524     and ordfeminine) are like this. This affected the treatment of \w and \W
  525     when they appeared in character classes, but not when they appeared outside
  526     a character class. The bit map for "word" characters is now created
  527     separately from the results of isalnum() instead of just taking it from the
  528     upper, lower, and digit maps. (Plus the underscore character, of course.)
  529 
  530  5. The above bug also affected the handling of POSIX character classes such as
  531     [[:alpha:]] and [[:alnum:]]. These do not have their own bit maps in PCRE's
  532     permanent tables. Instead, the bit maps for such a class were previously
  533     created as the appropriate unions of the upper, lower, and digit bitmaps.
  534     Now they are created by subtraction from the [[:word:]] class, which has
  535     its own bitmap.
  536 
  537  6. The [[:blank:]] character class matches horizontal, but not vertical space.
  538     It is created by subtracting the vertical space characters (\x09, \x0a,
  539     \x0b, \x0c) from the [[:space:]] bitmap. Previously, however, the
  540     subtraction was done in the overall bitmap for a character class, meaning
  541     that a class such as [\x0c[:blank:]] was incorrect because \x0c would not
  542     be recognized. This bug has been fixed.
  543 
  544  7. Patches from the folks at Google:
  545 
  546       (a) pcrecpp.cc: "to handle a corner case that may or may not happen in
  547       real life, but is still worth protecting against".
  548 
  549       (b) pcrecpp.cc: "corrects a bug when negative radixes are used with
  550       regular expressions".
  551 
  552       (c) pcre_scanner.cc: avoid use of std::count() because not all systems
  553       have it.
  554 
  555       (d) Split off pcrecpparg.h from pcrecpp.h and had the former built by
  556       "configure" and the latter not, in order to fix a problem somebody had
  557       with compiling the Arg class on HP-UX.
  558 
  559       (e) Improve the error-handling of the C++ wrapper a little bit.
  560 
  561       (f) New tests for checking recursion limiting.
  562 
  563  8. The pcre_memmove() function, which is used only if the environment does not
  564     have a standard memmove() function (and is therefore rarely compiled),
  565     contained two bugs: (a) use of int instead of size_t, and (b) it was not
  566     returning a result (though PCRE never actually uses the result).
  567 
  568  9. In the POSIX regexec() interface, if nmatch is specified as a ridiculously
  569     large number - greater than INT_MAX/(3*sizeof(int)) - REG_ESPACE is
  570     returned instead of calling malloc() with an overflowing number that would
  571     most likely cause subsequent chaos.
  572 
  573 10. The debugging option of pcretest was not showing the NO_AUTO_CAPTURE flag.
  574 
  575 11. The POSIX flag REG_NOSUB is now supported. When a pattern that was compiled
  576     with this option is matched, the nmatch and pmatch options of regexec() are
  577     ignored.
  578 
  579 12. Added REG_UTF8 to the POSIX interface. This is not defined by POSIX, but is
  580     provided in case anyone wants to the the POSIX interface with UTF-8
  581     strings.
  582 
  583 13. Added CXXLDFLAGS to the Makefile parameters to provide settings only on the
  584     C++ linking (needed for some HP-UX environments).
  585 
  586 14. Avoid compiler warnings in get_ucpname() when compiled without UCP support
  587     (unused parameter) and in the pcre_printint() function (omitted "default"
  588     switch label when the default is to do nothing).
  589 
  590 15. Added some code to make it possible, when PCRE is compiled as a C++
  591     library, to replace subject pointers for pcre_exec() with a smart pointer
  592     class, thus making it possible to process discontinuous strings.
  593 
  594 16. The two macros PCRE_EXPORT and PCRE_DATA_SCOPE are confusing, and perform
  595     much the same function. They were added by different people who were trying
  596     to make PCRE easy to compile on non-Unix systems. It has been suggested
  597     that PCRE_EXPORT be abolished now that there is more automatic apparatus
  598     for compiling on Windows systems. I have therefore replaced it with
  599     PCRE_DATA_SCOPE. This is set automatically for Windows; if not set it
  600     defaults to "extern" for C or "extern C" for C++, which works fine on
  601     Unix-like systems. It is now possible to override the value of PCRE_DATA_
  602     SCOPE with something explicit in config.h. In addition:
  603 
  604     (a) pcreposix.h still had just "extern" instead of either of these macros;
  605         I have replaced it with PCRE_DATA_SCOPE.
  606 
  607     (b) Functions such as _pcre_xclass(), which are internal to the library,
  608         but external in the C sense, all had PCRE_EXPORT in their definitions.
  609         This is apparently wrong for the Windows case, so I have removed it.
  610         (It makes no difference on Unix-like systems.)
  611 
  612 17. Added a new limit, MATCH_LIMIT_RECURSION, which limits the depth of nesting
  613     of recursive calls to match(). This is different to MATCH_LIMIT because
  614     that limits the total number of calls to match(), not all of which increase
  615     the depth of recursion. Limiting the recursion depth limits the amount of
  616     stack (or heap if NO_RECURSE is set) that is used. The default can be set
  617     when PCRE is compiled, and changed at run time. A patch from Google adds
  618     this functionality to the C++ interface.
  619 
  620 18. Changes to the handling of Unicode character properties:
  621 
  622     (a) Updated the table to Unicode 4.1.0.
  623 
  624     (b) Recognize characters that are not in the table as "Cn" (undefined).
  625 
  626     (c) I revised the way the table is implemented to a much improved format
  627         which includes recognition of ranges. It now supports the ranges that
  628         are defined in UnicodeData.txt, and it also amalgamates other
  629         characters into ranges. This has reduced the number of entries in the
  630         table from around 16,000 to around 3,000, thus reducing its size
  631         considerably. I realized I did not need to use a tree structure after
  632         all - a binary chop search is just as efficient. Having reduced the
  633         number of entries, I extended their size from 6 bytes to 8 bytes to
  634         allow for more data.
  635 
  636     (d) Added support for Unicode script names via properties such as \p{Han}.
  637 
  638 19. In UTF-8 mode, a backslash followed by a non-Ascii character was not
  639     matching that character.
  640 
  641 20. When matching a repeated Unicode property with a minimum greater than zero,
  642     (for example \pL{2,}), PCRE could look past the end of the subject if it
  643     reached it while seeking the minimum number of characters. This could
  644     happen only if some of the characters were more than one byte long, because
  645     there is a check for at least the minimum number of bytes.
  646 
  647 21. Refactored the implementation of \p and \P so as to be more general, to
  648     allow for more different types of property in future. This has changed the
  649     compiled form incompatibly. Anybody with saved compiled patterns that use
  650     \p or \P will have to recompile them.
  651 
  652 22. Added "Any" and "L&" to the supported property types.
  653 
  654 23. Recognize \x{...} as a code point specifier, even when not in UTF-8 mode,
  655     but give a compile time error if the value is greater than 0xff.
  656 
  657 24. The man pages for pcrepartial, pcreprecompile, and pcre_compile2 were
  658     accidentally not being installed or uninstalled.
  659 
  660 25. The pcre.h file was built from pcre.h.in, but the only changes that were
  661     made were to insert the current release number. This seemed silly, because
  662     it made things harder for people building PCRE on systems that don't run
  663     "configure". I have turned pcre.h into a distributed file, no longer built
  664     by "configure", with the version identification directly included. There is
  665     no longer a pcre.h.in file.
  666 
  667     However, this change necessitated a change to the pcre-config script as
  668     well. It is built from pcre-config.in, and one of the substitutions was the
  669     release number. I have updated configure.ac so that ./configure now finds
  670     the release number by grepping pcre.h.
  671 
  672 26. Added the ability to run the tests under valgrind.
  673 
  674 
  675 Version 6.4 05-Sep-05
  676 ---------------------
  677 
  678  1. Change 6.0/10/(l) to pcregrep introduced a bug that caused separator lines
  679     "--" to be printed when multiple files were scanned, even when none of the
  680     -A, -B, or -C options were used. This is not compatible with Gnu grep, so I
  681     consider it to be a bug, and have restored the previous behaviour.
  682 
  683  2. A couple of code tidies to get rid of compiler warnings.
  684 
  685  3. The pcretest program used to cheat by referring to symbols in the library
  686     whose names begin with _pcre_. These are internal symbols that are not
  687     really supposed to be visible externally, and in some environments it is
  688     possible to suppress them. The cheating is now confined to including
  689     certain files from the library's source, which is a bit cleaner.
  690 
  691  4. Renamed pcre.in as pcre.h.in to go with pcrecpp.h.in; it also makes the
  692     file's purpose clearer.
  693 
  694  5. Reorganized pcre_ucp_findchar().
  695 
  696 
  697 Version 6.3 15-Aug-05
  698 ---------------------
  699 
  700  1. The file libpcre.pc.in did not have general read permission in the tarball.
  701 
  702  2. There were some problems when building without C++ support:
  703 
  704     (a) If C++ support was not built, "make install" and "make test" still
  705         tried to test it.
  706 
  707     (b) There were problems when the value of CXX was explicitly set. Some
  708         changes have been made to try to fix these, and ...
  709 
  710     (c) --disable-cpp can now be used to explicitly disable C++ support.
  711 
  712     (d) The use of @CPP_OBJ@ directly caused a blank line preceded by a
  713         backslash in a target when C++ was disabled. This confuses some
  714         versions of "make", apparently. Using an intermediate variable solves
  715         this. (Same for CPP_LOBJ.)
  716 
  717  3. $(LINK_FOR_BUILD) now includes $(CFLAGS_FOR_BUILD) and $(LINK)
  718     (non-Windows) now includes $(CFLAGS) because these flags are sometimes
  719     necessary on certain architectures.
  720 
  721  4. Added a setting of -export-symbols-regex to the link command to remove
  722     those symbols that are exported in the C sense, but actually are local
  723     within the library, and not documented. Their names all begin with
  724     "_pcre_". This is not a perfect job, because (a) we have to except some
  725     symbols that pcretest ("illegally") uses, and (b) the facility isn't always
  726     available (and never for static libraries). I have made a note to try to
  727     find a way round (a) in the future.
  728 
  729 
  730 Version 6.2 01-Aug-05
  731 ---------------------
  732 
  733  1. There was no test for integer overflow of quantifier values. A construction
  734     such as {1111111111111111} would give undefined results. What is worse, if
  735     a minimum quantifier for a parenthesized subpattern overflowed and became
  736     negative, the calculation of the memory size went wrong. This could have
  737     led to memory overwriting.
  738 
  739  2. Building PCRE using VPATH was broken. Hopefully it is now fixed.
  740 
  741  3. Added "b" to the 2nd argument of fopen() in dftables.c, for non-Unix-like
  742     operating environments where this matters.
  743 
  744  4. Applied Giuseppe Maxia's patch to add additional features for controlling
  745     PCRE options from within the C++ wrapper.
  746 
  747  5. Named capturing subpatterns were not being correctly counted when a pattern
  748     was compiled. This caused two problems: (a) If there were more than 100
  749     such subpatterns, the calculation of the memory needed for the whole
  750     compiled pattern went wrong, leading to an overflow error. (b) Numerical
  751     back references of the form \12, where the number was greater than 9, were
  752     not recognized as back references, even though there were sufficient
  753     previous subpatterns.
  754 
  755  6. Two minor patches to pcrecpp.cc in order to allow it to compile on older
  756     versions of gcc, e.g. 2.95.4.
  757 
  758 
  759 Version 6.1 21-Jun-05
  760 ---------------------
  761 
  762  1. There was one reference to the variable "posix" in pcretest.c that was not
  763     surrounded by "#if !defined NOPOSIX".
  764 
  765  2. Make it possible to compile pcretest without DFA support, UTF8 support, or
  766     the cross-check on the old pcre_info() function, for the benefit of the
  767     cut-down version of PCRE that is currently imported into Exim.
  768 
  769  3. A (silly) pattern starting with (?i)(?-i) caused an internal space
  770     allocation error. I've done the easy fix, which wastes 2 bytes for sensible
  771     patterns that start (?i) but I don't think that matters. The use of (?i) is
  772     just an example; this all applies to the other options as well.
  773 
  774  4. Since libtool seems to echo the compile commands it is issuing, the output
  775     from "make" can be reduced a bit by putting "@" in front of each libtool
  776     compile command.
  777 
  778  5. Patch from the folks at Google for configure.in to be a bit more thorough
  779     in checking for a suitable C++ installation before trying to compile the
  780     C++ stuff. This should fix a reported problem when a compiler was present,
  781     but no suitable headers.
  782 
  783  6. The man pages all had just "PCRE" as their title. I have changed them to
  784     be the relevant file name. I have also arranged that these names are
  785     retained in the file doc/pcre.txt, which is a concatenation in text format
  786     of all the man pages except the little individual ones for each function.
  787 
  788  7. The NON-UNIX-USE file had not been updated for the different set of source
  789     files that come with release 6. I also added a few comments about the C++
  790     wrapper.
  791 
  792 
  793 Version 6.0 07-Jun-05
  794 ---------------------
  795 
  796  1. Some minor internal re-organization to help with my DFA experiments.
  797 
  798  2. Some missing #ifdef SUPPORT_UCP conditionals in pcretest and printint that
  799     didn't matter for the library itself when fully configured, but did matter
  800     when compiling without UCP support, or within Exim, where the ucp files are
  801     not imported.
  802 
  803  3. Refactoring of the library code to split up the various functions into
  804     different source modules. The addition of the new DFA matching code (see
  805     below) to a single monolithic source would have made it really too
  806     unwieldy, quite apart from causing all the code to be include in a
  807     statically linked application, when only some functions are used. This is
  808     relevant even without the DFA addition now that patterns can be compiled in
  809     one application and matched in another.
  810 
  811     The downside of splitting up is that there have to be some external
  812     functions and data tables that are used internally in different modules of
  813     the library but which are not part of the API. These have all had their
  814     names changed to start with "_pcre_" so that they are unlikely to clash
  815     with other external names.
  816 
  817  4. Added an alternate matching function, pcre_dfa_exec(), which matches using
  818     a different (DFA) algorithm. Although it is slower than the original
  819     function, it does have some advantages for certain types of matching
  820     problem.
  821 
  822  5. Upgrades to pcretest in order to test the features of pcre_dfa_exec(),
  823     including restarting after a partial match.
  824 
  825  6. A patch for pcregrep that defines INVALID_FILE_ATTRIBUTES if it is not
  826     defined when compiling for Windows was sent to me. I have put it into the
  827     code, though I have no means of testing or verifying it.
  828 
  829  7. Added the pcre_refcount() auxiliary function.
  830 
  831  8. Added the PCRE_FIRSTLINE option. This constrains an unanchored pattern to
  832     match before or at the first newline in the subject string. In pcretest,
  833     the /f option on a pattern can be used to set this.
  834 
  835  9. A repeated \w when used in UTF-8 mode with characters greater than 256
  836     would behave wrongly. This has been present in PCRE since release 4.0.
  837 
  838 10. A number of changes to the pcregrep command:
  839 
  840     (a) Refactored how -x works; insert ^(...)$ instead of setting
  841         PCRE_ANCHORED and checking the length, in preparation for adding
  842         something similar for -w.
  843 
  844     (b) Added the -w (match as a word) option.
  845 
  846     (c) Refactored the way lines are read and buffered so as to have more
  847         than one at a time available.
  848 
  849     (d) Implemented a pcregrep test script.
  850 
  851     (e) Added the -M (multiline match) option. This allows patterns to match
  852         over several lines of the subject. The buffering ensures that at least
  853         8K, or the rest of the document (whichever is the shorter) is available
  854         for matching (and similarly the previous 8K for lookbehind assertions).
  855 
  856     (f) Changed the --help output so that it now says
  857 
  858           -w, --word-regex(p)
  859 
  860         instead of two lines, one with "regex" and the other with "regexp"
  861         because that confused at least one person since the short forms are the
  862         same. (This required a bit of code, as the output is generated
  863         automatically from a table. It wasn't just a text change.)
  864 
  865     (g) -- can be used to terminate pcregrep options if the next thing isn't an
  866         option but starts with a hyphen. Could be a pattern or a path name
  867         starting with a hyphen, for instance.
  868 
  869     (h) "-" can be given as a file name to represent stdin.
  870 
  871     (i) When file names are being printed, "(standard input)" is used for
  872         the standard input, for compatibility with GNU grep. Previously
  873         "<stdin>" was used.
  874 
  875     (j) The option --label=xxx can be used to supply a name to be used for
  876         stdin when file names are being printed. There is no short form.
  877 
  878     (k) Re-factored the options decoding logic because we are going to add
  879         two more options that take data. Such options can now be given in four
  880         different ways, e.g. "-fname", "-f name", "--file=name", "--file name".
  881 
  882     (l) Added the -A, -B, and -C options for requesting that lines of context
  883         around matches be printed.
  884 
  885     (m) Added the -L option to print the names of files that do not contain
  886         any matching lines, that is, the complement of -l.
  887 
  888     (n) The return code is 2 if any file cannot be opened, but pcregrep does
  889         continue to scan other files.
  890 
  891     (o) The -s option was incorrectly implemented. For compatibility with other
  892         greps, it now suppresses the error message for a non-existent or non-
  893         accessible file (but not the return code). There is a new option called
  894         -q that suppresses the output of matching lines, which was what -s was
  895         previously doing.
  896 
  897     (p) Added --include and --exclude options to specify files for inclusion
  898         and exclusion when recursing.
  899 
  900 11. The Makefile was not using the Autoconf-supported LDFLAGS macro properly.
  901     Hopefully, it now does.
  902 
  903 12. Missing cast in pcre_study().
  904 
  905 13. Added an "uninstall" target to the makefile.
  906 
  907 14. Replaced "extern" in the function prototypes in Makefile.in with
  908     "PCRE_DATA_SCOPE", which defaults to 'extern' or 'extern "C"' in the Unix
  909     world, but is set differently for Windows.
  910 
  911 15. Added a second compiling function called pcre_compile2(). The only
  912     difference is that it has an extra argument, which is a pointer to an
  913     integer error code. When there is a compile-time failure, this is set
  914     non-zero, in addition to the error test pointer being set to point to an
  915     error message. The new argument may be NULL if no error number is required
  916     (but then you may as well call pcre_compile(), which is now just a
  917     wrapper). This facility is provided because some applications need a
  918     numeric error indication, but it has also enabled me to tidy up the way
  919     compile-time errors are handled in the POSIX wrapper.
  920 
  921 16. Added VPATH=.libs to the makefile; this should help when building with one
  922     prefix path and installing with another. (Or so I'm told by someone who
  923     knows more about this stuff than I do.)
  924 
  925 17. Added a new option, REG_DOTALL, to the POSIX function regcomp(). This
  926     passes PCRE_DOTALL to the pcre_compile() function, making the "." character
  927     match everything, including newlines. This is not POSIX-compatible, but
  928     somebody wanted the feature. From pcretest it can be activated by using
  929     both the P and the s flags.
  930 
  931 18. AC_PROG_LIBTOOL appeared twice in Makefile.in. Removed one.
  932 
  933 19. libpcre.pc was being incorrectly installed as executable.
  934 
  935 20. A couple of places in pcretest check for end-of-line by looking for '\n';
  936     it now also looks for '\r' so that it will work unmodified on Windows.
  937 
  938 21. Added Google's contributed C++ wrapper to the distribution.
  939 
  940 22. Added some untidy missing memory free() calls in pcretest, to keep
  941     Electric Fence happy when testing.
  942 
  943 
  944 
  945 Version 5.0 13-Sep-04
  946 ---------------------
  947 
  948  1. Internal change: literal characters are no longer packed up into items
  949     containing multiple characters in a single byte-string. Each character
  950     is now matched using a separate opcode. However, there may be more than one
  951     byte in the character in UTF-8 mode.
  952 
  953  2. The pcre_callout_block structure has two new fields: pattern_position and
  954     next_item_length. These contain the offset in the pattern to the next match
  955     item, and its length, respectively.
  956 
  957  3. The PCRE_AUTO_CALLOUT option for pcre_compile() requests the automatic
  958     insertion of callouts before each pattern item. Added the /C option to
  959     pcretest to make use of this.
  960 
  961  4. On the advice of a Windows user, the lines
  962 
  963       #if defined(_WIN32) || defined(WIN32)
  964       _setmode( _fileno( stdout ), 0x8000 );
  965       #endif  /* defined(_WIN32) || defined(WIN32) */
  966 
  967     have been added to the source of pcretest. This apparently does useful
  968     magic in relation to line terminators.
  969 
  970  5. Changed "r" and "w" in the calls to fopen() in pcretest to "rb" and "wb"
  971     for the benefit of those environments where the "b" makes a difference.
  972 
  973  6. The icc compiler has the same options as gcc, but "configure" doesn't seem
  974     to know about it. I have put a hack into configure.in that adds in code
  975     to set GCC=yes if CC=icc. This seems to end up at a point in the
  976     generated configure script that is early enough to affect the setting of
  977     compiler options, which is what is needed, but I have no means of testing
  978     whether it really works. (The user who reported this had patched the
  979     generated configure script, which of course I cannot do.)
  980 
  981     LATER: After change 22 below (new libtool files), the configure script
  982     seems to know about icc (and also ecc). Therefore, I have commented out
  983     this hack in configure.in.
  984 
  985  7. Added support for pkg-config (2 patches were sent in).
  986 
  987  8. Negated POSIX character classes that used a combination of internal tables
  988     were completely broken. These were [[:^alpha:]], [[:^alnum:]], and
  989     [[:^ascii]]. Typically, they would match almost any characters. The other
  990     POSIX classes were not broken in this way.
  991 
  992  9. Matching the pattern "\b.*?" against "ab cd", starting at offset 1, failed
  993     to find the match, as PCRE was deluded into thinking that the match had to
  994     start at the start point or following a newline. The same bug applied to
  995     patterns with negative forward assertions or any backward assertions
  996     preceding ".*" at the start, unless the pattern required a fixed first
  997     character. This was a failing pattern: "(?!.bcd).*". The bug is now fixed.
  998 
  999 10. In UTF-8 mode, when moving forwards in the subject after a failed match
 1000     starting at the last subject character, bytes beyond the end of the subject
 1001     string were read.
 1002 
 1003 11. Renamed the variable "class" as "classbits" to make life easier for C++
 1004     users. (Previously there was a macro definition, but it apparently wasn't
 1005     enough.)
 1006 
 1007 12. Added the new field "tables" to the extra data so that tables can be passed
 1008     in at exec time, or the internal tables can be re-selected. This allows
 1009     a compiled regex to be saved and re-used at a later time by a different
 1010     program that might have everything at different addresses.
 1011 
 1012 13. Modified the pcre-config script so that, when run on Solaris, it shows a
 1013     -R library as well as a -L library.
 1014 
 1015 14. The debugging options of pcretest (-d on the command line or D on a
 1016     pattern) showed incorrect output for anything following an extended class
 1017     that contained multibyte characters and which was followed by a quantifier.
 1018 
 1019 15. Added optional support for general category Unicode character properties
 1020     via the \p, \P, and \X escapes. Unicode property support implies UTF-8
 1021     support. It adds about 90K to the size of the library. The meanings of the
 1022     inbuilt class escapes such as \d and \s have NOT been changed.
 1023 
 1024 16. Updated pcredemo.c to include calls to free() to release the memory for the
 1025     compiled pattern.
 1026 
 1027 17. The generated file chartables.c was being created in the source directory
 1028     instead of in the building directory. This caused the build to fail if the
 1029     source directory was different from the building directory, and was
 1030     read-only.
 1031 
 1032 18. Added some sample Win commands from Mark Tetrode into the NON-UNIX-USE
 1033     file. No doubt somebody will tell me if they don't make sense... Also added
 1034     Dan Mooney's comments about building on OpenVMS.
 1035 
 1036 19. Added support for partial matching via the PCRE_PARTIAL option for
 1037     pcre_exec() and the \P data escape in pcretest.
 1038 
 1039 20. Extended pcretest with 3 new pattern features:
 1040 
 1041     (i)   A pattern option of the form ">rest-of-line" causes pcretest to
 1042           write the compiled pattern to the file whose name is "rest-of-line".
 1043           This is a straight binary dump of the data, with the saved pointer to
 1044           the character tables forced to be NULL. The study data, if any, is
 1045           written too. After writing, pcretest reads a new pattern.
 1046 
 1047     (ii)  If, instead of a pattern, "<rest-of-line" is given, pcretest reads a
 1048           compiled pattern from the given file. There must not be any
 1049           occurrences of "<" in the file name (pretty unlikely); if there are,
 1050           pcretest will instead treat the initial "<" as a pattern delimiter.
 1051           After reading in the pattern, pcretest goes on to read data lines as
 1052           usual.
 1053 
 1054     (iii) The F pattern option causes pcretest to flip the bytes in the 32-bit
 1055           and 16-bit fields in a compiled pattern, to simulate a pattern that
 1056           was compiled on a host of opposite endianness.
 1057 
 1058 21. The pcre-exec() function can now cope with patterns that were compiled on
 1059     hosts of opposite endianness, with this restriction:
 1060 
 1061       As for any compiled expression that is saved and used later, the tables
 1062       pointer field cannot be preserved; the extra_data field in the arguments
 1063       to pcre_exec() should be used to pass in a tables address if a value
 1064       other than the default internal tables were used at compile time.
 1065 
 1066 22. Calling pcre_exec() with a negative value of the "ovecsize" parameter is
 1067     now diagnosed as an error. Previously, most of the time, a negative number
 1068     would have been treated as zero, but if in addition "ovector" was passed as
 1069     NULL, a crash could occur.
 1070 
 1071 23. Updated the files ltmain.sh, config.sub, config.guess, and aclocal.m4 with
 1072     new versions from the libtool 1.5 distribution (the last one is a copy of
 1073     a file called libtool.m4). This seems to have fixed the need to patch
 1074     "configure" to support Darwin 1.3 (which I used to do). However, I still
 1075     had to patch ltmain.sh to ensure that ${SED} is set (it isn't on my
 1076     workstation).
 1077 
 1078 24. Changed the PCRE licence to be the more standard "BSD" licence.
 1079 
 1080 
 1081 Version 4.5 01-Dec-03
 1082 ---------------------
 1083 
 1084  1. There has been some re-arrangement of the code for the match() function so
 1085     that it can be compiled in a version that does not call itself recursively.
 1086     Instead, it keeps those local variables that need separate instances for
 1087     each "recursion" in a frame on the heap, and gets/frees frames whenever it
 1088     needs to "recurse". Keeping track of where control must go is done by means
 1089     of setjmp/longjmp. The whole thing is implemented by a set of macros that
 1090     hide most of the details from the main code, and operates only if
 1091     NO_RECURSE is defined while compiling pcre.c. If PCRE is built using the
 1092     "configure" mechanism, "--disable-stack-for-recursion" turns on this way of
 1093     operating.
 1094 
 1095     To make it easier for callers to provide specially tailored get/free
 1096     functions for this usage, two new functions, pcre_stack_malloc, and
 1097     pcre_stack_free, are used. They are always called in strict stacking order,
 1098     and the size of block requested is always the same.
 1099 
 1100     The PCRE_CONFIG_STACKRECURSE info parameter can be used to find out whether
 1101     PCRE has been compiled to use the stack or the heap for recursion. The
 1102     -C option of pcretest uses this to show which version is compiled.
 1103 
 1104     A new data escape \S, is added to pcretest; it causes the amounts of store
 1105     obtained and freed by both kinds of malloc/free at match time to be added
 1106     to the output.
 1107 
 1108  2. Changed the locale test to use "fr_FR" instead of "fr" because that's
 1109     what's available on my current Linux desktop machine.
 1110 
 1111  3. When matching a UTF-8 string, the test for a valid string at the start has
 1112     been extended. If start_offset is not zero, PCRE now checks that it points
 1113     to a byte that is the start of a UTF-8 character. If not, it returns
 1114     PCRE_ERROR_BADUTF8_OFFSET (-11). Note: the whole string is still checked;
 1115     this is necessary because there may be backward assertions in the pattern.
 1116     When matching the same subject several times, it may save resources to use
 1117     PCRE_NO_UTF8_CHECK on all but the first call if the string is long.
 1118 
 1119  4. The code for checking the validity of UTF-8 strings has been tightened so
 1120     that it rejects (a) strings containing 0xfe or 0xff bytes and (b) strings
 1121     containing "overlong sequences".
 1122 
 1123  5. Fixed a bug (appearing twice) that I could not find any way of exploiting!
 1124     I had written "if ((digitab[*p++] && chtab_digit) == 0)" where the "&&"
 1125     should have been "&", but it just so happened that all the cases this let
 1126     through by mistake were picked up later in the function.
 1127 
 1128  6. I had used a variable called "isblank" - this is a C99 function, causing
 1129     some compilers to warn. To avoid this, I renamed it (as "blankclass").
 1130 
 1131  7. Cosmetic: (a) only output another newline at the end of pcretest if it is
 1132     prompting; (b) run "./pcretest /dev/null" at the start of the test script
 1133     so the version is shown; (c) stop "make test" echoing "./RunTest".
 1134 
 1135  8. Added patches from David Burgess to enable PCRE to run on EBCDIC systems.
 1136 
 1137  9. The prototype for memmove() for systems that don't have it was using
 1138     size_t, but the inclusion of the header that defines size_t was later. I've
 1139     moved the #includes for the C headers earlier to avoid this.
 1140 
 1141 10. Added some adjustments to the code to make it easier to compiler on certain
 1142     special systems:
 1143 
 1144       (a) Some "const" qualifiers were missing.
 1145       (b) Added the macro EXPORT before all exported functions; by default this
 1146           is defined to be empty.
 1147       (c) Changed the dftables auxiliary program (that builds chartables.c) so
 1148           that it reads its output file name as an argument instead of writing
 1149           to the standard output and assuming this can be redirected.
 1150 
 1151 11. In UTF-8 mode, if a recursive reference (e.g. (?1)) followed a character
 1152     class containing characters with values greater than 255, PCRE compilation
 1153     went into a loop.
 1154 
 1155 12. A recursive reference to a subpattern that was within another subpattern
 1156     that had a minimum quantifier of zero caused PCRE to crash. For example,
 1157     (x(y(?2))z)? provoked this bug with a subject that got as far as the
 1158     recursion. If the recursively-called subpattern itself had a zero repeat,
 1159     that was OK.
 1160 
 1161 13. In pcretest, the buffer for reading a data line was set at 30K, but the
 1162     buffer into which it was copied (for escape processing) was still set at
 1163     1024, so long lines caused crashes.
 1164 
 1165 14. A pattern such as /[ab]{1,3}+/ failed to compile, giving the error
 1166     "internal error: code overflow...". This applied to any character class
 1167     that was followed by a possessive quantifier.
 1168 
 1169 15. Modified the Makefile to add libpcre.la as a prerequisite for
 1170     libpcreposix.la because I was told this is needed for a parallel build to
 1171     work.
 1172 
 1173 16. If a pattern that contained .* following optional items at the start was
 1174     studied, the wrong optimizing data was generated, leading to matching
 1175     errors. For example, studying /[ab]*.*c/ concluded, erroneously, that any
 1176     matching string must start with a or b or c. The correct conclusion for
 1177     this pattern is that a match can start with any character.
 1178 
 1179 
 1180 Version 4.4 13-Aug-03
 1181 ---------------------
 1182 
 1183  1. In UTF-8 mode, a character class containing characters with values between
 1184     127 and 255 was not handled correctly if the compiled pattern was studied.
 1185     In fixing this, I have also improved the studying algorithm for such
 1186     classes (slightly).
 1187 
 1188  2. Three internal functions had redundant arguments passed to them. Removal
 1189     might give a very teeny performance improvement.
 1190 
 1191  3. Documentation bug: the value of the capture_top field in a callout is *one
 1192     more than* the number of the hightest numbered captured substring.
 1193 
 1194  4. The Makefile linked pcretest and pcregrep with -lpcre, which could result
 1195     in incorrectly linking with a previously installed version. They now link
 1196     explicitly with libpcre.la.
 1197 
 1198  5. configure.in no longer needs to recognize Cygwin specially.
 1199 
 1200  6. A problem in pcre.in for Windows platforms is fixed.
 1201 
 1202  7. If a pattern was successfully studied, and the -d (or /D) flag was given to
 1203     pcretest, it used to include the size of the study block as part of its
 1204     output. Unfortunately, the structure contains a field that has a different
 1205     size on different hardware architectures. This meant that the tests that
 1206     showed this size failed. As the block is currently always of a fixed size,
 1207     this information isn't actually particularly useful in pcretest output, so
 1208     I have just removed it.
 1209 
 1210  8. Three pre-processor statements accidentally did not start in column 1.
 1211     Sadly, there are *still* compilers around that complain, even though
 1212     standard C has not required this for well over a decade. Sigh.
 1213 
 1214  9. In pcretest, the code for checking callouts passed small integers in the
 1215     callout_data field, which is a void * field. However, some picky compilers
 1216     complained about the casts involved for this on 64-bit systems. Now
 1217     pcretest passes the address of the small integer instead, which should get
 1218     rid of the warnings.
 1219 
 1220 10. By default, when in UTF-8 mode, PCRE now checks for valid UTF-8 strings at
 1221     both compile and run time, and gives an error if an invalid UTF-8 sequence
 1222     is found. There is a option for disabling this check in cases where the
 1223     string is known to be correct and/or the maximum performance is wanted.
 1224 
 1225 11. In response to a bug report, I changed one line in Makefile.in from
 1226 
 1227         -Wl,--out-implib,.libs/lib@WIN_PREFIX@pcreposix.dll.a \
 1228     to
 1229         -Wl,--out-implib,.libs/@WIN_PREFIX@libpcreposix.dll.a \
 1230 
 1231     to look similar to other lines, but I have no way of telling whether this
 1232     is the right thing to do, as I do not use Windows. No doubt I'll get told
 1233     if it's wrong...
 1234 
 1235 
 1236 Version 4.3 21-May-03
 1237 ---------------------
 1238 
 1239 1. Two instances of @WIN_PREFIX@ omitted from the Windows targets in the
 1240    Makefile.
 1241 
 1242 2. Some refactoring to improve the quality of the code:
 1243 
 1244    (i)   The utf8_table... variables are now declared "const".
 1245 
 1246    (ii)  The code for \cx, which used the "case flipping" table to upper case
 1247          lower case letters, now just substracts 32. This is ASCII-specific,
 1248          but the whole concept of \cx is ASCII-specific, so it seems
 1249          reasonable.
 1250 
 1251    (iii) PCRE was using its character types table to recognize decimal and
 1252          hexadecimal digits in the pattern. This is silly, because it handles
 1253          only 0-9, a-f, and A-F, but the character types table is locale-
 1254          specific, which means strange things might happen. A private
 1255          table is now used for this - though it costs 256 bytes, a table is
 1256          much faster than multiple explicit tests. Of course, the standard
 1257          character types table is still used for matching digits in subject
 1258          strings against \d.
 1259 
 1260    (iv)  Strictly, the identifier ESC_t is reserved by POSIX (all identifiers
 1261          ending in _t are). So I've renamed it as ESC_tee.
 1262 
 1263 3. The first argument for regexec() in the POSIX wrapper should have been
 1264    defined as "const".
 1265 
 1266 4. Changed pcretest to use malloc() for its buffers so that they can be
 1267    Electric Fenced for debugging.
 1268 
 1269 5. There were several places in the code where, in UTF-8 mode, PCRE would try
 1270    to read one or more bytes before the start of the subject string. Often this
 1271    had no effect on PCRE's behaviour, but in some circumstances it could
 1272    provoke a segmentation fault.
 1273 
 1274 6. A lookbehind at the start of a pattern in UTF-8 mode could also cause PCRE
 1275    to try to read one or more bytes before the start of the subject string.
 1276 
 1277 7. A lookbehind in a pattern matched in non-UTF-8 mode on a PCRE compiled with
 1278    UTF-8 support could misbehave in various ways if the subject string
 1279    contained bytes with the 0x80 bit set and the 0x40 bit unset in a lookbehind
 1280    area. (PCRE was not checking for the UTF-8 mode flag, and trying to move
 1281    back over UTF-8 characters.)
 1282 
 1283 
 1284 Version 4.2 14-Apr-03
 1285 ---------------------
 1286 
 1287 1. Typo "#if SUPPORT_UTF8" instead of "#ifdef SUPPORT_UTF8" fixed.
 1288 
 1289 2. Changes to the building process, supplied by Ronald Landheer-Cieslak
 1290      [ON_WINDOWS]: new variable, "#" on non-Windows platforms
 1291      [NOT_ON_WINDOWS]: new variable, "#" on Windows platforms
 1292      [WIN_PREFIX]: new variable, "cyg" for Cygwin
 1293      * Makefile.in: use autoconf substitution for OBJEXT, EXEEXT, BUILD_OBJEXT
 1294        and BUILD_EXEEXT
 1295      Note: automatic setting of the BUILD variables is not yet working
 1296      set CPPFLAGS and BUILD_CPPFLAGS (but don't use yet) - should be used at
 1297        compile-time but not at link-time
 1298      [LINK]: use for linking executables only
 1299      make different versions for Windows and non-Windows
 1300      [LINKLIB]: new variable, copy of UNIX-style LINK, used for linking
 1301        libraries
 1302      [LINK_FOR_BUILD]: new variable
 1303      [OBJEXT]: use throughout
 1304      [EXEEXT]: use throughout
 1305      <winshared>: new target
 1306      <wininstall>: new target
 1307      <dftables.o>: use native compiler
 1308      <dftables>: use native linker
 1309      <install>: handle Windows platform correctly
 1310      <clean>: ditto
 1311      <check>: ditto
 1312      copy DLL to top builddir before testing
 1313 
 1314    As part of these changes, -no-undefined was removed again. This was reported
 1315    to give trouble on HP-UX 11.0, so getting rid of it seems like a good idea
 1316    in any case.
 1317 
 1318 3. Some tidies to get rid of compiler warnings:
 1319 
 1320    . In the match_data structure, match_limit was an unsigned long int, whereas
 1321      match_call_count was an int. I've made them both unsigned long ints.
 1322 
 1323    . In pcretest the fact that a const uschar * doesn't automatically cast to
 1324      a void * provoked a warning.
 1325 
 1326    . Turning on some more compiler warnings threw up some "shadow" variables
 1327      and a few more missing casts.
 1328 
 1329 4. If PCRE was complied with UTF-8 support, but called without the PCRE_UTF8
 1330    option, a class that contained a single character with a value between 128
 1331    and 255 (e.g. /[\xFF]/) caused PCRE to crash.
 1332 
 1333 5. If PCRE was compiled with UTF-8 support, but called without the PCRE_UTF8
 1334    option, a class that contained several characters, but with at least one
 1335    whose value was between 128 and 255 caused PCRE to crash.
 1336 
 1337 
 1338 Version 4.1 12-Mar-03
 1339 ---------------------
 1340 
 1341 1. Compiling with gcc -pedantic found a couple of places where casts were
 1342 needed, and a string in dftables.c that was longer than standard compilers are
 1343 required to support.
 1344 
 1345 2. Compiling with Sun's compiler found a few more places where the code could
 1346 be tidied up in order to avoid warnings.
 1347 
 1348 3. The variables for cross-compiling were called HOST_CC and HOST_CFLAGS; the
 1349 first of these names is deprecated in the latest Autoconf in favour of the name
 1350 CC_FOR_BUILD, because "host" is typically used to mean the system on which the
 1351 compiled code will be run. I can't find a reference for HOST_CFLAGS, but by
 1352 analogy I have changed it to CFLAGS_FOR_BUILD.
 1353 
 1354 4. Added -no-undefined to the linking command in the Makefile, because this is
 1355 apparently helpful for Windows. To make it work, also added "-L. -lpcre" to the
 1356 linking step for the pcreposix library.
 1357 
 1358 5. PCRE was failing to diagnose the case of two named groups with the same
 1359 name.
 1360 
 1361 6. A problem with one of PCRE's optimizations was discovered. PCRE remembers a
 1362 literal character that is needed in the subject for a match, and scans along to
 1363 ensure that it is present before embarking on the full matching process. This
 1364 saves time in cases of nested unlimited repeats that are never going to match.
 1365 Problem: the scan can take a lot of time if the subject is very long (e.g.
 1366 megabytes), thus penalizing straightforward matches. It is now done only if the
 1367 amount of subject to be scanned is less than 1000 bytes.
 1368 
 1369 7. A lesser problem with the same optimization is that it was recording the
 1370 first character of an anchored pattern as "needed", thus provoking a search
 1371 right along the subject, even when the first match of the pattern was going to
 1372 fail. The "needed" character is now not set for anchored patterns, unless it
 1373 follows something in the pattern that is of non-fixed length. Thus, it still
 1374 fulfils its original purpose of finding quick non-matches in cases of nested
 1375 unlimited repeats, but isn't used for simple anchored patterns such as /^abc/.
 1376 
 1377 
 1378 Version 4.0 17-Feb-03
 1379 ---------------------
 1380 
 1381 1. If a comment in an extended regex that started immediately after a meta-item
 1382 extended to the end of string, PCRE compiled incorrect data. This could lead to
 1383 all kinds of weird effects. Example: /#/ was bad; /()#/ was bad; /a#/ was not.
 1384 
 1385 2. Moved to autoconf 2.53 and libtool 1.4.2.
 1386 
 1387 3. Perl 5.8 no longer needs "use utf8" for doing UTF-8 things. Consequently,
 1388 the special perltest8 script is no longer needed - all the tests can be run
 1389 from a single perltest script.
 1390 
 1391 4. From 5.004, Perl has not included the VT character (0x0b) in the set defined
 1392 by \s. It has now been removed in PCRE. This means it isn't recognized as
 1393 whitespace in /x regexes too, which is the same as Perl. Note that the POSIX
 1394 class [:space:] *does* include VT, thereby creating a mess.
 1395 
 1396 5. Added the class [:blank:] (a GNU extension from Perl 5.8) to match only
 1397 space and tab.
 1398 
 1399 6. Perl 5.005 was a long time ago. It's time to amalgamate the tests that use
 1400 its new features into the main test script, reducing the number of scripts.
 1401 
 1402 7. Perl 5.8 has changed the meaning of patterns like /a(?i)b/. Earlier versions
 1403 were backward compatible, and made the (?i) apply to the whole pattern, as if
 1404 /i were given. Now it behaves more logically, and applies the option setting
 1405 only to what follows. PCRE has been changed to follow suit. However, if it
 1406 finds options settings right at the start of the pattern, it extracts them into
 1407 the global options, as before. Thus, they show up in the info data.
 1408 
 1409 8. Added support for the \Q...\E escape sequence. Characters in between are
 1410 treated as literals. This is slightly different from Perl in that $ and @ are
 1411 also handled as literals inside the quotes. In Perl, they will cause variable
 1412 interpolation. Note the following examples:
 1413 
 1414     Pattern            PCRE matches      Perl matches
 1415 
 1416     \Qabc$xyz\E        abc$xyz           abc followed by the contents of $xyz
 1417     \Qabc\$xyz\E       abc\$xyz          abc\$xyz
 1418     \Qabc\E\$\Qxyz\E   abc$xyz           abc$xyz
 1419 
 1420 For compatibility with Perl, \Q...\E sequences are recognized inside character
 1421 classes as well as outside them.
 1422 
 1423 9. Re-organized 3 code statements in pcretest to avoid "overflow in
 1424 floating-point constant arithmetic" warnings from a Microsoft compiler. Added a
 1425 (size_t) cast to one statement in pcretest and one in pcreposix to avoid
 1426 signed/unsigned warnings.
 1427 
 1428 10. SunOS4 doesn't have strtoul(). This was used only for unpicking the -o
 1429 option for pcretest, so I've replaced it by a simple function that does just
 1430 that job.
 1431 
 1432 11. pcregrep was ending with code 0 instead of 2 for the commands "pcregrep" or
 1433 "pcregrep -".
 1434 
 1435 12. Added "possessive quantifiers" ?+, *+, ++, and {,}+ which come from Sun's
 1436 Java package. This provides some syntactic sugar for simple cases of what my
 1437 documentation calls "once-only subpatterns". A pattern such as x*+ is the same
 1438 as (?>x*). In other words, if what is inside (?>...) is just a single repeated
 1439 item, you can use this simplified notation. Note that only makes sense with
 1440 greedy quantifiers. Consequently, the use of the possessive quantifier forces
 1441 greediness, whatever the setting of the PCRE_UNGREEDY option.
 1442 
 1443 13. A change of greediness default within a pattern was not taking effect at
 1444 the current level for patterns like /(b+(?U)a+)/. It did apply to parenthesized
 1445 subpatterns that followed. Patterns like /b+(?U)a+/ worked because the option
 1446 was abstracted outside.
 1447 
 1448 14. PCRE now supports the \G assertion. It is true when the current matching
 1449 position is at the start point of the match. This differs from \A when the
 1450 starting offset is non-zero. Used with the /g option of pcretest (or similar
 1451 code), it works in the same way as it does for Perl's /g option. If all
 1452 alternatives of a regex begin with \G, the expression is anchored to the start
 1453 match position, and the "anchored" flag is set in the compiled expression.
 1454 
 1455 15. Some bugs concerning the handling of certain option changes within patterns
 1456 have been fixed. These applied to options other than (?ims). For example,
 1457 "a(?x: b c )d" did not match "XabcdY" but did match "Xa b c dY". It should have
 1458 been the other way round. Some of this was related to change 7 above.
 1459 
 1460 16. PCRE now gives errors for /[.x.]/ and /[=x=]/ as unsupported POSIX
 1461 features, as Perl does. Previously, PCRE gave the warnings only for /[[.x.]]/
 1462 and /[[=x=]]/. PCRE now also gives an error for /[:name:]/ because it supports
 1463 POSIX classes only within a class (e.g. /[[:alpha:]]/).
 1464 
 1465 17. Added support for Perl's \C escape. This matches one byte, even in UTF8
 1466 mode. Unlike ".", it always matches newline, whatever the setting of
 1467 PCRE_DOTALL. However, PCRE does not permit \C to appear in lookbehind
 1468 assertions. Perl allows it, but it doesn't (in general) work because it can't
 1469 calculate the length of the lookbehind. At least, that's the case for Perl
 1470 5.8.0 - I've been told they are going to document that it doesn't work in
 1471 future.
 1472 
 1473 18. Added an error diagnosis for escapes that PCRE does not support: these are
 1474 \L, \l, \N, \P, \p, \U, \u, and \X.
 1475 
 1476 19. Although correctly diagnosing a missing ']' in a character class, PCRE was
 1477 reading past the end of the pattern in cases such as /[abcd/.
 1478 
 1479 20. PCRE was getting more memory than necessary for patterns with classes that
 1480 contained both POSIX named classes and other characters, e.g. /[[:space:]abc/.
 1481 
 1482 21. Added some code, conditional on #ifdef VPCOMPAT, to make life easier for
 1483 compiling PCRE for use with Virtual Pascal.
 1484 
 1485 22. Small fix to the Makefile to make it work properly if the build is done
 1486 outside the source tree.
 1487 
 1488 23. Added a new extension: a condition to go with recursion. If a conditional
 1489 subpattern starts with (?(R) the "true" branch is used if recursion has
 1490 happened, whereas the "false" branch is used only at the top level.
 1491 
 1492 24. When there was a very long string of literal characters (over 255 bytes
 1493 without UTF support, over 250 bytes with UTF support), the computation of how
 1494 much memory was required could be incorrect, leading to segfaults or other
 1495 strange effects.
 1496 
 1497 25. PCRE was incorrectly assuming anchoring (either to start of subject or to
 1498 start of line for a non-DOTALL pattern) when a pattern started with (.*) and
 1499 there was a subsequent back reference to those brackets. This meant that, for
 1500 example, /(.*)\d+\1/ failed to match "abc123bc". Unfortunately, it isn't
 1501 possible to check for precisely this case. All we can do is abandon the
 1502 optimization if .* occurs inside capturing brackets when there are any back
 1503 references whatsoever. (See below for a better fix that came later.)
 1504 
 1505 26. The handling of the optimization for finding the first character of a
 1506 non-anchored pattern, and for finding a character that is required later in the
 1507 match were failing in some cases. This didn't break the matching; it just
 1508 failed to optimize when it could. The way this is done has been re-implemented.
 1509 
 1510 27. Fixed typo in error message for invalid (?R item (it said "(?p").
 1511 
 1512 28. Added a new feature that provides some of the functionality that Perl
 1513 provides with (?{...}). The facility is termed a "callout". The way it is done
 1514 in PCRE is for the caller to provide an optional function, by setting
 1515 pcre_callout to its entry point. Like pcre_malloc and pcre_free, this is a
 1516 global variable. By default it is unset, which disables all calling out. To get
 1517 the function called, the regex must include (?C) at appropriate points. This
 1518 is, in fact, equivalent to (?C0), and any number <= 255 may be given with (?C).
 1519 This provides a means of identifying different callout points. When PCRE
 1520 reaches such a point in the regex, if pcre_callout has been set, the external
 1521 function is called. It is provided with data in a structure called
 1522 pcre_callout_block, which is defined in pcre.h. If the function returns 0,
 1523 matching continues; if it returns a non-zero value, the match at the current
 1524 point fails. However, backtracking will occur if possible. [This was changed
 1525 later and other features added - see item 49 below.]
 1526 
 1527 29. pcretest is upgraded to test the callout functionality. It provides a
 1528 callout function that displays information. By default, it shows the start of
 1529 the match and the current position in the text. There are some new data escapes
 1530 to vary what happens:
 1531 
 1532     \C+         in addition, show current contents of captured substrings
 1533     \C-         do not supply a callout function
 1534     \C!n        return 1 when callout number n is reached
 1535     \C!n!m      return 1 when callout number n is reached for the mth time
 1536 
 1537 30. If pcregrep was called with the -l option and just a single file name, it
 1538 output "<stdin>" if a match was found, instead of the file name.
 1539 
 1540 31. Improve the efficiency of the POSIX API to PCRE. If the number of capturing
 1541 slots is less than POSIX_MALLOC_THRESHOLD, use a block on the stack to pass to
 1542 pcre_exec(). This saves a malloc/free per call. The default value of
 1543 POSIX_MALLOC_THRESHOLD is 10; it can be changed by --with-posix-malloc-threshold
 1544 when configuring.
 1545 
 1546 32. The default maximum size of a compiled pattern is 64K. There have been a
 1547 few cases of people hitting this limit. The code now uses macros to handle the
 1548 storing of links as offsets within the compiled pattern. It defaults to 2-byte
 1549 links, but this can be changed to 3 or 4 bytes by --with-link-size when
 1550 configuring. Tests 2 and 5 work only with 2-byte links because they output
 1551 debugging information about compiled patterns.
 1552 
 1553 33. Internal code re-arrangements:
 1554 
 1555 (a) Moved the debugging function for printing out a compiled regex into
 1556     its own source file (printint.c) and used #include to pull it into
 1557     pcretest.c and, when DEBUG is defined, into pcre.c, instead of having two
 1558     separate copies.
 1559 
 1560 (b) Defined the list of op-code names for debugging as a macro in
 1561     internal.h so that it is next to the definition of the opcodes.
 1562 
 1563 (c) Defined a table of op-code lengths for simpler skipping along compiled
 1564     code. This is again a macro in internal.h so that it is next to the
 1565     definition of the opcodes.
 1566 
 1567 34. Added support for recursive calls to individual subpatterns, along the
 1568 lines of Robin Houston's patch (but implemented somewhat differently).
 1569 
 1570 35. Further mods to the Makefile to help Win32. Also, added code to pcregrep to
 1571 allow it to read and process whole directories in Win32. This code was
 1572 contributed by Lionel Fourquaux; it has not been tested by me.
 1573 
 1574 36. Added support for named subpatterns. The Python syntax (?P<name>...) is
 1575 used to name a group. Names consist of alphanumerics and underscores, and must
 1576 be unique. Back references use the syntax (?P=name) and recursive calls use
 1577 (?P>name) which is a PCRE extension to the Python extension. Groups still have
 1578 numbers. The function pcre_fullinfo() can be used after compilation to extract
 1579 a name/number map. There are three relevant calls:
 1580 
 1581   PCRE_INFO_NAMEENTRYSIZE        yields the size of each entry in the map
 1582   PCRE_INFO_NAMECOUNT            yields the number of entries
 1583   PCRE_INFO_NAMETABLE            yields a pointer to the map.
 1584 
 1585 The map is a vector of fixed-size entries. The size of each entry depends on
 1586 the length of the longest name used. The first two bytes of each entry are the
 1587 group number, most significant byte first. There follows the corresponding
 1588 name, zero terminated. The names are in alphabetical order.
 1589 
 1590 37. Make the maximum literal string in the compiled code 250 for the non-UTF-8
 1591 case instead of 255. Making it the same both with and without UTF-8 support
 1592 means that the same test output works with both.
 1593 
 1594 38. There was a case of malloc(0) in the POSIX testing code in pcretest. Avoid
 1595 calling malloc() with a zero argument.
 1596 
 1597 39. Change 25 above had to resort to a heavy-handed test for the .* anchoring
 1598 optimization. I've improved things by keeping a bitmap of backreferences with
 1599 numbers 1-31 so that if .* occurs inside capturing brackets that are not in
 1600 fact referenced, the optimization can be applied. It is unlikely that a
 1601 relevant occurrence of .* (i.e. one which might indicate anchoring or forcing
 1602 the match to follow \n) will appear inside brackets with a number greater than
 1603 31, but if it does, any back reference > 31 suppresses the optimization.
 1604 
 1605 40. Added a new compile-time option PCRE_NO_AUTO_CAPTURE. This has the effect
 1606 of disabling numbered capturing parentheses. Any opening parenthesis that is
 1607 not followed by ? behaves as if it were followed by ?: but named parentheses
 1608 can still be used for capturing (and they will acquire numbers in the usual
 1609 way).
 1610 
 1611 41. Redesigned the return codes from the match() function into yes/no/error so
 1612 that errors can be passed back from deep inside the nested calls. A malloc
 1613 failure while inside a recursive subpattern call now causes the
 1614 PCRE_ERROR_NOMEMORY return instead of quietly going wrong.
 1615 
 1616 42. It is now possible to set a limit on the number of times the match()
 1617 function is called in a call to pcre_exec(). This facility makes it possible to
 1618 limit the amount of recursion and backtracking, though not in a directly
 1619 obvious way, because the match() function is used in a number of different
 1620 circumstances. The count starts from zero for each position in the subject
 1621 string (for non-anchored patterns). The default limit is, for compatibility, a
 1622 large number, namely 10 000 000. You can change this in two ways:
 1623 
 1624 (a) When configuring PCRE before making, you can use --with-match-limit=n
 1625     to set a default value for the compiled library.
 1626 
 1627 (b) For each call to pcre_exec(), you can pass a pcre_extra block in which
 1628     a different value is set. See 45 below.
 1629 
 1630 If the limit is exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT.
 1631 
 1632 43. Added a new function pcre_config(int, void *) to enable run-time extraction
 1633 of things that can be changed at compile time. The first argument specifies
 1634 what is wanted and the second points to where the information is to be placed.
 1635 The current list of available information is:
 1636 
 1637   PCRE_CONFIG_UTF8
 1638 
 1639 The output is an integer that is set to one if UTF-8 support is available;
 1640 otherwise it is set to zero.
 1641 
 1642   PCRE_CONFIG_NEWLINE
 1643 
 1644 The output is an integer that it set to the value of the code that is used for
 1645 newline. It is either LF (10) or CR (13).
 1646 
 1647   PCRE_CONFIG_LINK_SIZE
 1648 
 1649 The output is an integer that contains the number of bytes used for internal
 1650 linkage in compiled expressions. The value is 2, 3, or 4. See item 32 above.
 1651 
 1652   PCRE_CONFIG_POSIX_MALLOC_THRESHOLD
 1653 
 1654 The output is an integer that contains the threshold above which the POSIX
 1655 interface uses malloc() for output vectors. See item 31 above.
 1656 
 1657   PCRE_CONFIG_MATCH_LIMIT
 1658 
 1659 The output is an unsigned integer that contains the default limit of the number
 1660 of match() calls in a pcre_exec() execution. See 42 above.
 1661 
 1662 44. pcretest has been upgraded by the addition of the -C option. This causes it
 1663 to extract all the available output from the new pcre_config() function, and to
 1664 output it. The program then exits immediately.
 1665 
 1666 45. A need has arisen to pass over additional data with calls to pcre_exec() in
 1667 order to support additional features. One way would have been to define
 1668 pcre_exec2() (for example) with extra arguments, but this would not have been
 1669 extensible, and would also have required all calls to the original function to
 1670 be mapped to the new one. Instead, I have chosen to extend the mechanism that
 1671 is used for passing in "extra" data from pcre_study().
 1672 
 1673 The pcre_extra structure is now exposed and defined in pcre.h. It currently
 1674 contains the following fields:
 1675 
 1676   flags         a bitmap indicating which of the following fields are set
 1677   study_data    opaque data from pcre_study()
 1678   match_limit   a way of specifying a limit on match() calls for a specific
 1679                   call to pcre_exec()
 1680   callout_data  data for callouts (see 49 below)
 1681 
 1682 The flag bits are also defined in pcre.h, and are
 1683 
 1684   PCRE_EXTRA_STUDY_DATA
 1685   PCRE_EXTRA_MATCH_LIMIT
 1686   PCRE_EXTRA_CALLOUT_DATA
 1687 
 1688 The pcre_study() function now returns one of these new pcre_extra blocks, with
 1689 the actual study data pointed to by the study_data field, and the
 1690 PCRE_EXTRA_STUDY_DATA flag set. This can be passed directly to pcre_exec() as
 1691 before. That is, this change is entirely upwards-compatible and requires no
 1692 change to existing code.
 1693 
 1694 If you want to pass in additional data to pcre_exec(), you can either place it
 1695 in a pcre_extra block provided by pcre_study(), or create your own pcre_extra
 1696 block.
 1697 
 1698 46. pcretest has been extended to test the PCRE_EXTRA_MATCH_LIMIT feature. If a
 1699 data string contains the escape sequence \M, pcretest calls pcre_exec() several
 1700 times with different match limits, until it finds the minimum value needed for
 1701 pcre_exec() to complete. The value is then output. This can be instructive; for
 1702 most simple matches the number is quite small, but for pathological cases it
 1703 gets very large very quickly.
 1704 
 1705 47. There's a new option for pcre_fullinfo() called PCRE_INFO_STUDYSIZE. It
 1706 returns the size of the data block pointed to by the study_data field in a
 1707 pcre_extra block, that is, the value that was passed as the argument to
 1708 pcre_malloc() when PCRE was getting memory in which to place the information
 1709 created by pcre_study(). The fourth argument should point to a size_t variable.
 1710 pcretest has been extended so that this information is shown after a successful
 1711 pcre_study() call when information about the compiled regex is being displayed.
 1712 
 1713 48. Cosmetic change to Makefile: there's no need to have / after $(DESTDIR)
 1714 because what follows is always an absolute path. (Later: it turns out that this
 1715 is more than cosmetic for MinGW, because it doesn't like empty path
 1716 components.)
 1717 
 1718 49. Some changes have been made to the callout feature (see 28 above):
 1719 
 1720 (i)  A callout function now has three choices for what it returns:
 1721 
 1722        0  =>  success, carry on matching
 1723      > 0  =>  failure at this point, but backtrack if possible
 1724      < 0  =>  serious error, return this value from pcre_exec()
 1725 
 1726      Negative values should normally be chosen from the set of PCRE_ERROR_xxx
 1727      values. In particular, returning PCRE_ERROR_NOMATCH forces a standard
 1728      "match failed" error. The error number PCRE_ERROR_CALLOUT is reserved for
 1729      use by callout functions. It will never be used by PCRE itself.
 1730 
 1731 (ii) The pcre_extra structure (see 45 above) has a void * field called
 1732      callout_data, with corresponding flag bit PCRE_EXTRA_CALLOUT_DATA. The
 1733      pcre_callout_block structure has a field of the same name. The contents of
 1734      the field passed in the pcre_extra structure are passed to the callout
 1735      function in the corresponding field in the callout block. This makes it
 1736      easier to use the same callout-containing regex from multiple threads. For
 1737      testing, the pcretest program has a new data escape
 1738 
 1739        \C*n        pass the number n (may be negative) as callout_data
 1740 
 1741      If the callout function in pcretest receives a non-zero value as
 1742      callout_data, it returns that value.
 1743 
 1744 50. Makefile wasn't handling CFLAGS properly when compiling dftables. Also,
 1745 there were some redundant $(CFLAGS) in commands that are now specified as
 1746 $(LINK), which already includes $(CFLAGS).
 1747 
 1748 51. Extensions to UTF-8 support are listed below. These all apply when (a) PCRE
 1749 has been compiled with UTF-8 support *and* pcre_compile() has been compiled
 1750 with the PCRE_UTF8 flag. Patterns that are compiled without that flag assume
 1751 one-byte characters throughout. Note that case-insensitive matching applies
 1752 only to characters whose values are less than 256. PCRE doesn't support the
 1753 notion of cases for higher-valued characters.
 1754 
 1755 (i)   A character class whose characters are all within 0-255 is handled as
 1756       a bit map, and the map is inverted for negative classes. Previously, a
 1757       character > 255 always failed to match such a class; however it should
 1758       match if the class was a negative one (e.g. [^ab]). This has been fixed.
 1759 
 1760 (ii)  A negated character class with a single character < 255 is coded as
 1761       "not this character" (OP_NOT). This wasn't working properly when the test
 1762       character was multibyte, either singly or repeated.
 1763 
 1764 (iii) Repeats of multibyte characters are now handled correctly in UTF-8
 1765       mode, for example: \x{100}{2,3}.
 1766 
 1767 (iv)  The character escapes \b, \B, \d, \D, \s, \S, \w, and \W (either
 1768       singly or repeated) now correctly test multibyte characters. However,
 1769       PCRE doesn't recognize any characters with values greater than 255 as
 1770       digits, spaces, or word characters. Such characters always match \D, \S,
 1771       and \W, and never match \d, \s, or \w.
 1772 
 1773 (v)   Classes may now contain characters and character ranges with values
 1774       greater than 255. For example: [ab\x{100}-\x{400}].
 1775 
 1776 (vi)  pcregrep now has a --utf-8 option (synonym -u) which makes it call
 1777       PCRE in UTF-8 mode.
 1778 
 1779 52. The info request value PCRE_INFO_FIRSTCHAR has been renamed
 1780 PCRE_INFO_FIRSTBYTE because it is a byte value. However, the old name is
 1781 retained for backwards compatibility. (Note that LASTLITERAL is also a byte
 1782 value.)
 1783 
 1784 53. The single man page has become too large. I have therefore split it up into
 1785 a number of separate man pages. These also give rise to individual HTML pages;
 1786 these are now put in a separate directory, and there is an index.html page that
 1787 lists them all. Some hyperlinking between the pages has been installed.
 1788 
 1789 54. Added convenience functions for handling named capturing parentheses.
 1790 
 1791 55. Unknown escapes inside character classes (e.g. [\M]) and escapes that
 1792 aren't interpreted therein (e.g. [\C]) are literals in Perl. This is now also
 1793 true in PCRE, except when the PCRE_EXTENDED option is set, in which case they
 1794 are faulted.
 1795 
 1796 56. Introduced HOST_CC and HOST_CFLAGS which can be set in the environment when
 1797 calling configure. These values are used when compiling the dftables.c program
 1798 which is run to generate the source of the default character tables. They
 1799 default to the values of CC and CFLAGS. If you are cross-compiling PCRE,
 1800 you will need to set these values.
 1801 
 1802 57. Updated the building process for Windows DLL, as provided by Fred Cox.
 1803 
 1804 
 1805 Version 3.9 02-Jan-02
 1806 ---------------------
 1807 
 1808 1. A bit of extraneous text had somehow crept into the pcregrep documentation.
 1809 
 1810 2. If --disable-static was given, the building process failed when trying to
 1811 build pcretest and pcregrep. (For some reason it was using libtool to compile
 1812 them, which is not right, as they aren't part of the library.)
 1813 
 1814 
 1815 Version 3.8 18-Dec-01
 1816 ---------------------
 1817 
 1818 1. The experimental UTF-8 code was completely screwed up. It was packing the
 1819 bytes in the wrong order. How dumb can you get?
 1820 
 1821 
 1822 Version 3.7 29-Oct-01
 1823 ---------------------
 1824 
 1825 1. In updating pcretest to check change 1 of version 3.6, I screwed up.
 1826 This caused pcretest, when used on the test data, to segfault. Unfortunately,
 1827 this didn't happen under Solaris 8, where I normally test things.
 1828 
 1829 2. The Makefile had to be changed to make it work on BSD systems, where 'make'
 1830 doesn't seem to recognize that ./xxx and xxx are the same file. (This entry
 1831 isn't in ChangeLog distributed with 3.7 because I forgot when I hastily made
 1832 this fix an hour or so after the initial 3.7 release.)
 1833 
 1834 
 1835 Version 3.6 23-Oct-01
 1836 ---------------------
 1837 
 1838 1. Crashed with /(sens|respons)e and \1ibility/ and "sense and sensibility" if
 1839 offsets passed as NULL with zero offset count.
 1840 
 1841 2. The config.guess and config.sub files had not been updated when I moved to
 1842 the latest autoconf.
 1843 
 1844 
 1845 Version 3.5 15-Aug-01
 1846 ---------------------
 1847 
 1848 1. Added some missing #if !defined NOPOSIX conditionals in pcretest.c that
 1849 had been forgotten.
 1850 
 1851 2. By using declared but undefined structures, we can avoid using "void"
 1852 definitions in pcre.h while keeping the internal definitions of the structures
 1853 private.
 1854 
 1855 3. The distribution is now built using autoconf 2.50 and libtool 1.4. From a
 1856 user point of view, this means that both static and shared libraries are built
 1857 by default, but this can be individually controlled. More of the work of
 1858 handling this static/shared cases is now inside libtool instead of PCRE's make
 1859 file.
 1860 
 1861 4. The pcretest utility is now installed along with pcregrep because it is
 1862 useful for users (to test regexs) and by doing this, it automatically gets
 1863 relinked by libtool. The documentation has been turned into a man page, so
 1864 there are now .1, .txt, and .html versions in /doc.
 1865 
 1866 5. Upgrades to pcregrep:
 1867    (i)   Added long-form option names like gnu grep.
 1868    (ii)  Added --help to list all options with an explanatory phrase.
 1869    (iii) Added -r, --recursive to recurse into sub-directories.
 1870    (iv)  Added -f, --file to read patterns from a file.
 1871 
 1872 6. pcre_exec() was referring to its "code" argument before testing that
 1873 argument for NULL (and giving an error if it was NULL).
 1874 
 1875 7. Upgraded Makefile.in to allow for compiling in a different directory from
 1876 the source directory.
 1877 
 1878 8. Tiny buglet in pcretest: when pcre_fullinfo() was called to retrieve the
 1879 options bits, the pointer it was passed was to an int instead of to an unsigned
 1880 long int. This mattered only on 64-bit systems.
 1881 
 1882 9. Fixed typo (3.4/1) in pcre.h again. Sigh. I had changed pcre.h (which is
 1883 generated) instead of pcre.in, which it its source. Also made the same change
 1884 in several of the .c files.
 1885 
 1886 10. A new release of gcc defines printf() as a macro, which broke pcretest
 1887 because it had an ifdef in the middle of a string argument for printf(). Fixed
 1888 by using separate calls to printf().
 1889 
 1890 11. Added --enable-newline-is-cr and --enable-newline-is-lf to the configure
 1891 script, to force use of CR or LF instead of \n in the source. On non-Unix
 1892 systems, the value can be set in config.h.
 1893 
 1894 12. The limit of 200 on non-capturing parentheses is a _nesting_ limit, not an
 1895 absolute limit. Changed the text of the error message to make this clear, and
 1896 likewise updated the man page.
 1897 
 1898 13. The limit of 99 on the number of capturing subpatterns has been removed.
 1899 The new limit is 65535, which I hope will not be a "real" limit.
 1900 
 1901 
 1902 Version 3.4 22-Aug-00
 1903 ---------------------
 1904 
 1905 1. Fixed typo in pcre.h: unsigned const char * changed to const unsigned char *.
 1906 
 1907 2. Diagnose condition (?(0) as an error instead of crashing on matching.
 1908 
 1909 
 1910 Version 3.3 01-Aug-00
 1911 ---------------------
 1912 
 1913 1. If an octal character was given, but the value was greater than \377, it
 1914 was not getting masked to the least significant bits, as documented. This could
 1915 lead to crashes in some systems.
 1916 
 1917 2. Perl 5.6 (if not earlier versions) accepts classes like [a-\d] and treats
 1918 the hyphen as a literal. PCRE used to give an error; it now behaves like Perl.
 1919 
 1920 3. Added the functions pcre_free_substring() and pcre_free_substring_list().
 1921 These just pass their arguments on to (pcre_free)(), but they are provided
 1922 because some uses of PCRE bind it to non-C systems that can call its functions,
 1923 but cannot call free() or pcre_free() directly.
 1924 
 1925 4. Add "make test" as a synonym for "make check". Corrected some comments in
 1926 the Makefile.
 1927 
 1928 5. Add $(DESTDIR)/ in front of all the paths in the "install" target in the
 1929 Makefile.
 1930 
 1931 6. Changed the name of pgrep to pcregrep, because Solaris has introduced a
 1932 command called pgrep for grepping around the active processes.
 1933 
 1934 7. Added the beginnings of support for UTF-8 character strings.
 1935 
 1936 8. Arranged for the Makefile to pass over the settings of CC, CFLAGS, and
 1937 RANLIB to ./ltconfig so that they are used by libtool. I think these are all
 1938 the relevant ones. (AR is not passed because ./ltconfig does its own figuring
 1939 out for the ar command.)
 1940 
 1941 
 1942 Version 3.2 12-May-00
 1943 ---------------------
 1944 
 1945 This is purely a bug fixing release.
 1946 
 1947 1. If the pattern /((Z)+|A)*/ was matched agained ZABCDEFG it matched Z instead
 1948 of ZA. This was just one example of several cases that could provoke this bug,
 1949 which was introduced by change 9 of version 2.00. The code for breaking
 1950 infinite loops after an iteration that matches an empty string was't working
 1951 correctly.
 1952 
 1953 2. The pcretest program was not imitating Perl correctly for the pattern /a*/g
 1954 when matched against abbab (for example). After matching an empty string, it
 1955 wasn't forcing anchoring when setting PCRE_NOTEMPTY for the next attempt; this
 1956 caused it to match further down the string than it should.
 1957 
 1958 3. The code contained an inclusion of sys/types.h. It isn't clear why this
 1959 was there because it doesn't seem to be needed, and it causes trouble on some
 1960 systems, as it is not a Standard C header. It has been removed.
 1961 
 1962 4. Made 4 silly changes to the source to avoid stupid compiler warnings that
 1963 were reported on the Macintosh. The changes were from
 1964 
 1965   while ((c = *(++ptr)) != 0 && c != '\n');
 1966 to
 1967   while ((c = *(++ptr)) != 0 && c != '\n') ;
 1968 
 1969 Totally extraordinary, but if that's what it takes...
 1970 
 1971 5. PCRE is being used in one environment where neither memmove() nor bcopy() is
 1972 available. Added HAVE_BCOPY and an autoconf test for it; if neither
 1973 HAVE_MEMMOVE nor HAVE_BCOPY is set, use a built-in emulation function which
 1974 assumes the way PCRE uses memmove() (always moving upwards).
 1975 
 1976 6. PCRE is being used in one environment where strchr() is not available. There
 1977 was only one use in pcre.c, and writing it out to avoid strchr() probably gives
 1978 faster code anyway.
 1979 
 1980 
 1981 Version 3.1 09-Feb-00
 1982 ---------------------
 1983 
 1984 The only change in this release is the fixing of some bugs in Makefile.in for
 1985 the "install" target:
 1986 
 1987 (1) It was failing to install pcreposix.h.
 1988 
 1989 (2) It was overwriting the pcre.3 man page with the pcreposix.3 man page.
 1990 
 1991 
 1992 Version 3.0 01-Feb-00
 1993 ---------------------
 1994 
 1995 1. Add support for the /+ modifier to perltest (to output $` like it does in
 1996 pcretest).
 1997 
 1998 2. Add support for the /g modifier to perltest.
 1999 
 2000 3. Fix pcretest so that it behaves even more like Perl for /g when the pattern
 2001 matches null strings.
 2002 
 2003 4. Fix perltest so that it doesn't do unwanted things when fed an empty
 2004 pattern. Perl treats empty patterns specially - it reuses the most recent
 2005 pattern, which is not what we want. Replace // by /(?#)/ in order to avoid this
 2006 effect.
 2007 
 2008 5. The POSIX interface was broken in that it was just handing over the POSIX
 2009 captured string vector to pcre_exec(), but (since release 2.00) PCRE has
 2010 required a bigger vector, with some working space on the end. This means that
 2011 the POSIX wrapper now has to get and free some memory, and copy the results.
 2012 
 2013 6. Added some simple autoconf support, placing the test data and the
 2014 documentation in separate directories, re-organizing some of the
 2015 information files, and making it build pcre-config (a GNU standard). Also added
 2016 libtool support for building PCRE as a shared library, which is now the
 2017 default.
 2018 
 2019 7. Got rid of the leading zero in the definition of PCRE_MINOR because 08 and
 2020 09 are not valid octal constants. Single digits will be used for minor values
 2021 less than 10.
 2022 
 2023 8. Defined REG_EXTENDED and REG_NOSUB as zero in the POSIX header, so that
 2024 existing programs that set these in the POSIX interface can use PCRE without
 2025 modification.
 2026 
 2027 9. Added a new function, pcre_fullinfo() with an extensible interface. It can
 2028 return all that pcre_info() returns, plus additional data. The pcre_info()
 2029 function is retained for compatibility, but is considered to be obsolete.
 2030 
 2031 10. Added experimental recursion feature (?R) to handle one common case that
 2032 Perl 5.6 will be able to do with (?p{...}).
 2033 
 2034 11. Added support for POSIX character classes like [:alpha:], which Perl is
 2035 adopting.
 2036 
 2037 
 2038 Version 2.08 31-Aug-99
 2039 ----------------------
 2040 
 2041 1. When startoffset was not zero and the pattern began with ".*", PCRE was not
 2042 trying to match at the startoffset position, but instead was moving forward to
 2043 the next newline as if a previous match had failed.
 2044 
 2045 2. pcretest was not making use of PCRE_NOTEMPTY when repeating for /g and /G,
 2046 and could get into a loop if a null string was matched other than at the start
 2047 of the subject.
 2048 
 2049 3. Added definitions of PCRE_MAJOR and PCRE_MINOR to pcre.h so the version can
 2050 be distinguished at compile time, and for completeness also added PCRE_DATE.
 2051 
 2052 5. Added Paul Sokolovsky's minor changes to make it easy to compile a Win32 DLL
 2053 in GnuWin32 environments.
 2054 
 2055 
 2056 Version 2.07 29-Jul-99
 2057 ----------------------
 2058 
 2059 1. The documentation is now supplied in plain text form and HTML as well as in
 2060 the form of man page sources.
 2061 
 2062 2. C++ compilers don't like assigning (void *) values to other pointer types.
 2063 In particular this affects malloc(). Although there is no problem in Standard
 2064 C, I've put in casts to keep C++ compilers happy.
 2065 
 2066 3. Typo on pcretest.c; a cast of (unsigned char *) in the POSIX regexec() call
 2067 should be (const char *).
 2068 
 2069 4. If NOPOSIX is defined, pcretest.c compiles without POSIX support. This may
 2070 be useful for non-Unix systems who don't want to bother with the POSIX stuff.
 2071 However, I haven't made this a standard facility. The documentation doesn't
 2072 mention it, and the Makefile doesn't support it.
 2073 
 2074 5. The Makefile now contains an "install" target, with editable destinations at
 2075 the top of the file. The pcretest program is not installed.
 2076 
 2077 6. pgrep -V now gives the PCRE version number and date.
 2078 
 2079 7. Fixed bug: a zero repetition after a literal string (e.g. /abcde{0}/) was
 2080 causing the entire string to be ignored, instead of just the last character.
 2081 
 2082 8. If a pattern like /"([^\\"]+|\\.)*"/ is applied in the normal way to a
 2083 non-matching string, it can take a very, very long time, even for strings of
 2084 quite modest length, because of the nested recursion. PCRE now does better in
 2085 some of these cases. It does this by remembering the last required literal
 2086 character in the pattern, and pre-searching the subject to ensure it is present
 2087 before running the real match. In other words, it applies a heuristic to detect
 2088 some types of certain failure quickly, and in the above example, if presented
 2089 with a string that has no trailing " it gives "no match" very quickly.
 2090 
 2091 9. A new runtime option PCRE_NOTEMPTY causes null string matches to be ignored;
 2092 other alternatives are tried instead.
 2093 
 2094 
 2095 Version 2.06 09-Jun-99
 2096 ----------------------
 2097 
 2098 1. Change pcretest's output for amount of store used to show just the code
 2099 space, because the remainder (the data block) varies in size between 32-bit and
 2100 64-bit systems.
 2101 
 2102 2. Added an extra argument to pcre_exec() to supply an offset in the subject to
 2103 start matching at. This allows lookbehinds to work when searching for multiple
 2104 occurrences in a string.
 2105 
 2106 3. Added additional options to pcretest for testing multiple occurrences:
 2107 
 2108    /+   outputs the rest of the string that follows a match
 2109    /g   loops for multiple occurrences, using the new startoffset argument
 2110    /G   loops for multiple occurrences by passing an incremented pointer
 2111 
 2112 4. PCRE wasn't doing the "first character" optimization for patterns starting
 2113 with \b or \B, though it was doing it for other lookbehind assertions. That is,
 2114 it wasn't noticing that a match for a pattern such as /\bxyz/ has to start with
 2115 the letter 'x'. On long subject strings, this gives a significant speed-up.
 2116 
 2117 
 2118 Version 2.05 21-Apr-99
 2119 ----------------------
 2120 
 2121 1. Changed the type of magic_number from int to long int so that it works
 2122 properly on 16-bit systems.
 2123 
 2124 2. Fixed a bug which caused patterns starting with .* not to work correctly
 2125 when the subject string contained newline characters. PCRE was assuming
 2126 anchoring for such patterns in all cases, which is not correct because .* will
 2127 not pass a newline unless PCRE_DOTALL is set. It now assumes anchoring only if
 2128 DOTALL is set at top level; otherwise it knows that patterns starting with .*
 2129 must be retried after every newline in the subject.
 2130 
 2131 
 2132 Version 2.04 18-Feb-99
 2133 ----------------------
 2134 
 2135 1. For parenthesized subpatterns with repeats whose minimum was zero, the
 2136 computation of the store needed to hold the pattern was incorrect (too large).
 2137 If such patterns were nested a few deep, this could multiply and become a real
 2138 problem.
 2139 
 2140 2. Added /M option to pcretest to show the memory requirement of a specific
 2141 pattern. Made -m a synonym of -s (which does this globally) for compatibility.
 2142 
 2143 3. Subpatterns of the form (regex){n,m} (i.e. limited maximum) were being
 2144 compiled in such a way that the backtracking after subsequent failure was
 2145 pessimal. Something like (a){0,3} was compiled as (a)?(a)?(a)? instead of
 2146 ((a)((a)(a)?)?)? with disastrous performance if the maximum was of any size.
 2147 
 2148 
 2149 Version 2.03 02-Feb-99
 2150 ----------------------
 2151 
 2152 1. Fixed typo and small mistake in man page.
 2153 
 2154 2. Added 4th condition (GPL supersedes if conflict) and created separate
 2155 LICENCE file containing the conditions.
 2156 
 2157 3. Updated pcretest so that patterns such as /abc\/def/ work like they do in
 2158 Perl, that is the internal \ allows the delimiter to be included in the
 2159 pattern. Locked out the use of \ as a delimiter. If \ immediately follows
 2160 the final delimiter, add \ to the end of the pattern (to test the error).
 2161 
 2162 4. Added the convenience functions for extracting substrings after a successful
 2163 match. Updated pcretest to make it able to test these functions.
 2164 
 2165 
 2166 Version 2.02 14-Jan-99
 2167 ----------------------
 2168 
 2169 1. Initialized the working variables associated with each extraction so that
 2170 their saving and restoring doesn't refer to uninitialized store.
 2171 
 2172 2. Put dummy code into study.c in order to trick the optimizer of the IBM C
 2173 compiler for OS/2 into generating correct code. Apparently IBM isn't going to
 2174 fix the problem.
 2175 
 2176 3. Pcretest: the timing code wasn't using LOOPREPEAT for timing execution
 2177 calls, and wasn't printing the correct value for compiling calls. Increased the
 2178 default value of LOOPREPEAT, and the number of significant figures in the
 2179 times.
 2180 
 2181 4. Changed "/bin/rm" in the Makefile to "-rm" so it works on Windows NT.
 2182 
 2183 5. Renamed "deftables" as "dftables" to get it down to 8 characters, to avoid
 2184 a building problem on Windows NT with a FAT file system.
 2185 
 2186 
 2187 Version 2.01 21-Oct-98
 2188 ----------------------
 2189 
 2190 1. Changed the API for pcre_compile() to allow for the provision of a pointer
 2191 to character tables built by pcre_maketables() in the current locale. If NULL
 2192 is passed, the default tables are used.
 2193 
 2194 
 2195 Version 2.00 24-Sep-98
 2196 ----------------------
 2197 
 2198 1. Since the (>?) facility is in Perl 5.005, don't require PCRE_EXTRA to enable
 2199 it any more.
 2200 
 2201 2. Allow quantification of (?>) groups, and make it work correctly.
 2202 
 2203 3. The first character computation wasn't working for (?>) groups.
 2204 
 2205 4. Correct the implementation of \Z (it is permitted to match on the \n at the
 2206 end of the subject) and add 5.005's \z, which really does match only at the
 2207 very end of the subject.
 2208 
 2209 5. Remove the \X "cut" facility; Perl doesn't have it, and (?> is neater.
 2210 
 2211 6. Remove the ability to specify CASELESS, MULTILINE, DOTALL, and
 2212 DOLLAR_END_ONLY at runtime, to make it possible to implement the Perl 5.005
 2213 localized options. All options to pcre_study() were also removed.
 2214 
 2215 7. Add other new features from 5.005:
 2216 
 2217    $(?<=           positive lookbehind
 2218    $(?<!           negative lookbehind
 2219    (?imsx-imsx)    added the unsetting capability
 2220                    such a setting is global if at outer level; local otherwise
 2221    (?imsx-imsx:)   non-capturing groups with option setting
 2222    (?(cond)re|re)  conditional pattern matching
 2223 
 2224    A backreference to itself in a repeated group matches the previous
 2225    captured string.
 2226 
 2227 8. General tidying up of studying (both automatic and via "study")
 2228 consequential on the addition of new assertions.
 2229 
 2230 9. As in 5.005, unlimited repeated groups that could match an empty substring
 2231 are no longer faulted at compile time. Instead, the loop is forcibly broken at
 2232 runtime if any iteration does actually match an empty substring.
 2233 
 2234 10. Include the RunTest script in the distribution.
 2235 
 2236 11. Added tests from the Perl 5.005_02 distribution. This showed up a few
 2237 discrepancies, some of which were old and were also with respect to 5.004. They
 2238 have now been fixed.
 2239 
 2240 
 2241 Version 1.09 28-Apr-98
 2242 ----------------------
 2243 
 2244 1. A negated single character class followed by a quantifier with a minimum
 2245 value of one (e.g.  [^x]{1,6}  ) was not compiled correctly. This could lead to
 2246 program crashes, or just wrong answers. This did not apply to negated classes
 2247 containing more than one character, or to minima other than one.
 2248 
 2249 
 2250 Version 1.08 27-Mar-98
 2251 ----------------------
 2252 
 2253 1. Add PCRE_UNGREEDY to invert the greediness of quantifiers.
 2254 
 2255 2. Add (?U) and (?X) to set PCRE_UNGREEDY and PCRE_EXTRA respectively. The
 2256 latter must appear before anything that relies on it in the pattern.
 2257 
 2258 
 2259 Version 1.07 16-Feb-98
 2260 ----------------------
 2261 
 2262 1. A pattern such as /((a)*)*/ was not being diagnosed as in error (unlimited
 2263 repeat of a potentially empty string).
 2264 
 2265 
 2266 Version 1.06 23-Jan-98
 2267 ----------------------
 2268 
 2269 1. Added Markus Oberhumer's little patches for C++.
 2270 
 2271 2. Literal strings longer than 255 characters were broken.
 2272 
 2273 
 2274 Version 1.05 23-Dec-97
 2275 ----------------------
 2276 
 2277 1. Negated character classes containing more than one character were failing if
 2278 PCRE_CASELESS was set at run time.
 2279 
 2280 
 2281 Version 1.04 19-Dec-97
 2282 ----------------------
 2283 
 2284 1. Corrected the man page, where some "const" qualifiers had been omitted.
 2285 
 2286 2. Made debugging output print "{0,xxx}" instead of just "{,xxx}" to agree with
 2287 input syntax.
 2288 
 2289 3. Fixed memory leak which occurred when a regex with back references was
 2290 matched with an offsets vector that wasn't big enough. The temporary memory
 2291 that is used in this case wasn't being freed if the match failed.
 2292 
 2293 4. Tidied pcretest to ensure it frees memory that it gets.
 2294 
 2295 5. Temporary memory was being obtained in the case where the passed offsets
 2296 vector was exactly big enough.
 2297 
 2298 6. Corrected definition of offsetof() from change 5 below.
 2299 
 2300 7. I had screwed up change 6 below and broken the rules for the use of
 2301 setjmp(). Now fixed.
 2302 
 2303 
 2304 Version 1.03 18-Dec-97
 2305 ----------------------
 2306 
 2307 1. A erroneous regex with a missing opening parenthesis was correctly
 2308 diagnosed, but PCRE attempted to access brastack[-1], which could cause crashes
 2309 on some systems.
 2310 
 2311 2. Replaced offsetof(real_pcre, code) by offsetof(real_pcre, code[0]) because
 2312 it was reported that one broken compiler failed on the former because "code" is
 2313 also an independent variable.
 2314 
 2315 3. The erroneous regex a[]b caused an array overrun reference.
 2316 
 2317 4. A regex ending with a one-character negative class (e.g. /[^k]$/) did not
 2318 fail on data ending with that character. (It was going on too far, and checking
 2319 the next character, typically a binary zero.) This was specific to the
 2320 optimized code for single-character negative classes.
 2321 
 2322 5. Added a contributed patch from the TIN world which does the following:
 2323 
 2324   + Add an undef for memmove, in case the the system defines a macro for it.
 2325 
 2326   + Add a definition of offsetof(), in case there isn't one. (I don't know
 2327     the reason behind this - offsetof() is part of the ANSI standard - but
 2328     it does no harm).
 2329 
 2330   + Reduce the ifdef's in pcre.c using macro DPRINTF, thereby eliminating
 2331     most of the places where whitespace preceded '#'. I have given up and
 2332     allowed the remaining 2 cases to be at the margin.
 2333 
 2334   + Rename some variables in pcre to eliminate shadowing. This seems very
 2335     pedantic, but does no harm, of course.
 2336 
 2337 6. Moved the call to setjmp() into its own function, to get rid of warnings
 2338 from gcc -Wall, and avoided calling it at all unless PCRE_EXTRA is used.
 2339 
 2340 7. Constructs such as \d{8,} were compiling into the equivalent of
 2341 \d{8}\d{0,65527} instead of \d{8}\d* which didn't make much difference to the
 2342 outcome, but in this particular case used more store than had been allocated,
 2343 which caused the bug to be discovered because it threw up an internal error.
 2344 
 2345 8. The debugging code in both pcre and pcretest for outputting the compiled
 2346 form of a regex was going wrong in the case of back references followed by
 2347 curly-bracketed repeats.
 2348 
 2349 
 2350 Version 1.02 12-Dec-97
 2351 ----------------------
 2352 
 2353 1. Typos in pcre.3 and comments in the source fixed.
 2354 
 2355 2. Applied a contributed patch to get rid of places where it used to remove
 2356 'const' from variables, and fixed some signed/unsigned and uninitialized
 2357 variable warnings.
 2358 
 2359 3. Added the "runtest" target to Makefile.
 2360 
 2361 4. Set default compiler flag to -O2 rather than just -O.
 2362 
 2363 
 2364 Version 1.01 19-Nov-97
 2365 ----------------------
 2366 
 2367 1. PCRE was failing to diagnose unlimited repeat of empty string for patterns
 2368 like /([ab]*)*/, that is, for classes with more than one character in them.
 2369 
 2370 2. Likewise, it wasn't diagnosing patterns with "once-only" subpatterns, such
 2371 as /((?>a*))*/ (a PCRE_EXTRA facility).
 2372 
 2373 
 2374 Version 1.00 18-Nov-97
 2375 ----------------------
 2376 
 2377 1. Added compile-time macros to support systems such as SunOS4 which don't have
 2378 memmove() or strerror() but have other things that can be used instead.
 2379 
 2380 2. Arranged that "make clean" removes the executables.
 2381 
 2382 
 2383 Version 0.99 27-Oct-97
 2384 ----------------------
 2385 
 2386 1. Fixed bug in code for optimizing classes with only one character. It was
 2387 initializing a 32-byte map regardless, which could cause it to run off the end
 2388 of the memory it had got.
 2389 
 2390 2. Added, conditional on PCRE_EXTRA, the proposed (?>REGEX) construction.
 2391 
 2392 
 2393 Version 0.98 22-Oct-97
 2394 ----------------------
 2395 
 2396 1. Fixed bug in code for handling temporary memory usage when there are more
 2397 back references than supplied space in the ovector. This could cause segfaults.
 2398 
 2399 
 2400 Version 0.97 21-Oct-97
 2401 ----------------------
 2402 
 2403 1. Added the \X "cut" facility, conditional on PCRE_EXTRA.
 2404 
 2405 2. Optimized negated single characters not to use a bit map.
 2406 
 2407 3. Brought error texts together as macro definitions; clarified some of them;
 2408 fixed one that was wrong - it said "range out of order" when it meant "invalid
 2409 escape sequence".
 2410 
 2411 4. Changed some char * arguments to const char *.
 2412 
 2413 5. Added PCRE_NOTBOL and PCRE_NOTEOL (from POSIX).
 2414 
 2415 6. Added the POSIX-style API wrapper in pcreposix.a and testing facilities in
 2416 pcretest.
 2417 
 2418 
 2419 Version 0.96 16-Oct-97
 2420 ----------------------
 2421 
 2422 1. Added a simple "pgrep" utility to the distribution.
 2423 
 2424 2. Fixed an incompatibility with Perl: "{" is now treated as a normal character
 2425 unless it appears in one of the precise forms "{ddd}", "{ddd,}", or "{ddd,ddd}"
 2426 where "ddd" means "one or more decimal digits".
 2427 
 2428 3. Fixed serious bug. If a pattern had a back reference, but the call to
 2429 pcre_exec() didn't supply a large enough ovector to record the related
 2430 identifying subpattern, the match always failed. PCRE now remembers the number
 2431 of the largest back reference, and gets some temporary memory in which to save
 2432 the offsets during matching if necessary, in order to ensure that
 2433 backreferences always work.
 2434 
 2435 4. Increased the compatibility with Perl in a number of ways:
 2436 
 2437   (a) . no longer matches \n by default; an option PCRE_DOTALL is provided
 2438       to request this handling. The option can be set at compile or exec time.
 2439 
 2440   (b) $ matches before a terminating newline by default; an option
 2441       PCRE_DOLLAR_ENDONLY is provided to override this (but not in multiline
 2442       mode). The option can be set at compile or exec time.
 2443 
 2444   (c) The handling of \ followed by a digit other than 0 is now supposed to be
 2445       the same as Perl's. If the decimal number it represents is less than 10
 2446       or there aren't that many previous left capturing parentheses, an octal
 2447       escape is read. Inside a character class, it's always an octal escape,
 2448       even if it is a single digit.
 2449 
 2450   (d) An escaped but undefined alphabetic character is taken as a literal,
 2451       unless PCRE_EXTRA is set. Currently this just reserves the remaining
 2452       escapes.
 2453 
 2454   (e) {0} is now permitted. (The previous item is removed from the compiled
 2455       pattern).
 2456 
 2457 5. Changed all the names of code files so that the basic parts are no longer
 2458 than 10 characters, and abolished the teeny "globals.c" file.
 2459 
 2460 6. Changed the handling of character classes; they are now done with a 32-byte
 2461 bit map always.
 2462 
 2463 7. Added the -d and /D options to pcretest to make it possible to look at the
 2464 internals of compilation without having to recompile pcre.
 2465 
 2466 
 2467 Version 0.95 23-Sep-97
 2468 ----------------------
 2469 
 2470 1. Fixed bug in pre-pass concerning escaped "normal" characters such as \x5c or
 2471 \x20 at the start of a run of normal characters. These were being treated as
 2472 real characters, instead of the source characters being re-checked.
 2473 
 2474 
 2475 Version 0.94 18-Sep-97
 2476 ----------------------
 2477 
 2478 1. The functions are now thread-safe, with the caveat that the global variables
 2479 containing pointers to malloc() and free() or alternative functions are the
 2480 same for all threads.
 2481 
 2482 2. Get pcre_study() to generate a bitmap of initial characters for non-
 2483 anchored patterns when this is possible, and use it if passed to pcre_exec().
 2484 
 2485 
 2486 Version 0.93 15-Sep-97
 2487 ----------------------
 2488 
 2489 1. /(b)|(:+)/ was computing an incorrect first character.
 2490 
 2491 2. Add pcre_study() to the API and the passing of pcre_extra to pcre_exec(),
 2492 but not actually doing anything yet.
 2493 
 2494 3. Treat "-" characters in classes that cannot be part of ranges as literals,
 2495 as Perl does (e.g. [-az] or [az-]).
 2496 
 2497 4. Set the anchored flag if a branch starts with .* or .*? because that tests
 2498 all possible positions.
 2499 
 2500 5. Split up into different modules to avoid including unneeded functions in a
 2501 compiled binary. However, compile and exec are still in one module. The "study"
 2502 function is split off.
 2503 
 2504 6. The character tables are now in a separate module whose source is generated
 2505 by an auxiliary program - but can then be edited by hand if required. There are
 2506 now no calls to isalnum(), isspace(), isdigit(), isxdigit(), tolower() or
 2507 toupper() in the code.
 2508 
 2509 7. Turn the malloc/free funtions variables into pcre_malloc and pcre_free and
 2510 make them global. Abolish the function for setting them, as the caller can now
 2511 set them directly.
 2512 
 2513 
 2514 Version 0.92 11-Sep-97
 2515 ----------------------
 2516 
 2517 1. A repeat with a fixed maximum and a minimum of 1 for an ordinary character
 2518 (e.g. /a{1,3}/) was broken (I mis-optimized it).
 2519 
 2520 2. Caseless matching was not working in character classes if the characters in
 2521 the pattern were in upper case.
 2522 
 2523 3. Make ranges like [W-c] work in the same way as Perl for caseless matching.
 2524 
 2525 4. Make PCRE_ANCHORED public and accept as a compile option.
 2526 
 2527 5. Add an options word to pcre_exec() and accept PCRE_ANCHORED and
 2528 PCRE_CASELESS at run time. Add escapes \A and \I to pcretest to cause it to
 2529 pass them.
 2530 
 2531 6. Give an error if bad option bits passed at compile or run time.
 2532 
 2533 7. Add PCRE_MULTILINE at compile and exec time, and (?m) as well. Add \M to
 2534 pcretest to cause it to pass that flag.
 2535 
 2536 8. Add pcre_info(), to get the number of identifying subpatterns, the stored
 2537 options, and the first character, if set.
 2538 
 2539 9. Recognize C+ or C{n,m} where n >= 1 as providing a fixed starting character.
 2540 
 2541 
 2542 Version 0.91 10-Sep-97
 2543 ----------------------
 2544 
 2545 1. PCRE was failing to diagnose unlimited repeats of subpatterns that could
 2546 match the empty string as in /(a*)*/. It was looping and ultimately crashing.
 2547 
 2548 2. PCRE was looping on encountering an indefinitely repeated back reference to
 2549 a subpattern that had matched an empty string, e.g. /(a|)\1*/. It now does what
 2550 Perl does - treats the match as successful.
 2551 
 2552 ****