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-revision 57 by nigel,
Sat Feb 24 21:39:50 2007 UTC
+revision 73 by nigel,
Sat Feb 24 21:40:30 2007 UTC
 Line 1
  ChangeLog for PCRE
  ------------------
+ Version 4.5 01-Dec-03
+ ---------------------
+. There has been some re-arrangement of the code for the match() function so
+     that it can be compiled in a version that does not call itself recursively.
+     Instead, it keeps those local variables that need separate instances for
+     each "recursion" in a frame on the heap, and gets/frees frames whenever it
+     needs to "recurse". Keeping track of where control must go is done by means
+     of setjmp/longjmp. The whole thing is implemented by a set of macros that
+     hide most of the details from the main code, and operates only if
+     NO_RECURSE is defined while compiling pcre.c. If PCRE is built using the
+     "configure" mechanism, "--disable-stack-for-recursion" turns on this way of
+     operating.
+     To make it easier for callers to provide specially tailored get/free
+     functions for this usage, two new functions, pcre_stack_malloc, and
+     pcre_stack_free, are used. They are always called in strict stacking order,
+     and the size of block requested is always the same.
+     The PCRE_CONFIG_STACKRECURSE info parameter can be used to find out whether
+     PCRE has been compiled to use the stack or the heap for recursion. The
+     -C option of pcretest uses this to show which version is compiled.
+     A new data escape \S, is added to pcretest; it causes the amounts of store
+     obtained and freed by both kinds of malloc/free at match time to be added
+     to the output.
+. Changed the locale test to use "fr_FR" instead of "fr" because that's
+     what's available on my current Linux desktop machine.
+. When matching a UTF-8 string, the test for a valid string at the start has
+     been extended. If start_offset is not zero, PCRE now checks that it points
+     to a byte that is the start of a UTF-8 character. If not, it returns
+     PCRE_ERROR_BADUTF8_OFFSET (-11). Note: the whole string is still checked;
+     this is necessary because there may be backward assertions in the pattern.
+     When matching the same subject several times, it may save resources to use
+     PCRE_NO_UTF8_CHECK on all but the first call if the string is long.
+. The code for checking the validity of UTF-8 strings has been tightened so
+     that it rejects (a) strings containing 0xfe or 0xff bytes and (b) strings
+     containing "overlong sequences".
+. Fixed a bug (appearing twice) that I could not find any way of exploiting!
+     I had written "if ((digitab[*p++] && chtab_digit) == 0)" where the "&&"
+     should have been "&", but it just so happened that all the cases this let
+     through by mistake were picked up later in the function.
+. I had used a variable called "isblank" - this is a C99 function, causing
+     some compilers to warn. To avoid this, I renamed it (as "blankclass").
+. Cosmetic: (a) only output another newline at the end of pcretest if it is
+     prompting; (b) run "./pcretest /dev/null" at the start of the test script
+     so the version is shown; (c) stop "make test" echoing "./RunTest".
+. Added patches from David Burgess to enable PCRE to run on EBCDIC systems.
+. The prototype for memmove() for systems that don't have it was using
+     size_t, but the inclusion of the header that defines size_t was later. I've
+     moved the #includes for the C headers earlier to avoid this.
+. Added some adjustments to the code to make it easier to compiler on certain
+     special systems:
+       (a) Some "const" qualifiers were missing.
+       (b) Added the macro EXPORT before all exported functions; by default this
+           is defined to be empty.
+       (c) Changed the dftables auxiliary program (that builds chartables.c) so
+           that it reads its output file name as an argument instead of writing
+           to the standard output and assuming this can be redirected.
+. In UTF-8 mode, if a recursive reference (e.g. (?1)) followed a character
+     class containing characters with values greater than 255, PCRE compilation
+     went into a loop.
+. A recursive reference to a subpattern that was within another subpattern
+     that had a minimum quantifier of zero caused PCRE to crash. For example,
+     (x(y(?2))z)? provoked this bug with a subject that got as far as the
+     recursion. If the recursively-called subpattern itself had a zero repeat,
+     that was OK.
+. In pcretest, the buffer for reading a data line was set at 30K, but the
+     buffer into which it was copied (for escape processing) was still set at
+, so long lines caused crashes.
+. A pattern such as /[ab]{1,3}+/ failed to compile, giving the error
+     "internal error: code overflow...". This applied to any character class
+     that was followed by a possessive quantifier.
+. Modified the Makefile to add libpcre.la as a prerequisite for
+     libpcreposix.la because I was told this is needed for a parallel build to
+     work.
+. If a pattern that contained .* following optional items at the start was
+     studied, the wrong optimizing data was generated, leading to matching
+     errors. For example, studying /[ab]*.*c/ concluded, erroneously, that any
+     matching string must start with a or b or c. The correct conclusion for
+     this pattern is that a match can start with any character.
+ Version 4.4 13-Aug-03
+ ---------------------
+. In UTF-8 mode, a character class containing characters with values between
+and 255 was not handled correctly if the compiled pattern was studied.
+     In fixing this, I have also improved the studying algorithm for such
+     classes (slightly).
+. Three internal functions had redundant arguments passed to them. Removal
+     might give a very teeny performance improvement.
+. Documentation bug: the value of the capture_top field in a callout is *one
+     more than* the number of the hightest numbered captured substring.
+. The Makefile linked pcretest and pcregrep with -lpcre, which could result
+     in incorrectly linking with a previously installed version. They now link
+     explicitly with libpcre.la.
+. configure.in no longer needs to recognize Cygwin specially.
+. A problem in pcre.in for Windows platforms is fixed.
+. If a pattern was successfully studied, and the -d (or /D) flag was given to
+     pcretest, it used to include the size of the study block as part of its
+     output. Unfortunately, the structure contains a field that has a different
+     size on different hardware architectures. This meant that the tests that
+     showed this size failed. As the block is currently always of a fixed size,
+     this information isn't actually particularly useful in pcretest output, so
+     I have just removed it.
+. Three pre-processor statements accidentally did not start in column 1.
+     Sadly, there are *still* compilers around that complain, even though
+     standard C has not required this for well over a decade. Sigh.
+. In pcretest, the code for checking callouts passed small integers in the
+     callout_data field, which is a void * field. However, some picky compilers
+     complained about the casts involved for this on 64-bit systems. Now
+     pcretest passes the address of the small integer instead, which should get
+     rid of the warnings.
+. By default, when in UTF-8 mode, PCRE now checks for valid UTF-8 strings at
+     both compile and run time, and gives an error if an invalid UTF-8 sequence
+     is found. There is a option for disabling this check in cases where the
+     string is known to be correct and/or the maximum performance is wanted.
+. In response to a bug report, I changed one line in Makefile.in from
+         -Wl,--out-implib,.libs/lib@WIN_PREFIX@pcreposix.dll.a \
+     to
+         -Wl,--out-implib,.libs/@WIN_PREFIX@libpcreposix.dll.a \
+     to look similar to other lines, but I have no way of telling whether this
+     is the right thing to do, as I do not use Windows. No doubt I'll get told
+     if it's wrong...
+ Version 4.3 21-May-03
+ ---------------------
+. Two instances of @WIN_PREFIX@ omitted from the Windows targets in the
+    Makefile.
+. Some refactoring to improve the quality of the code:
+    (i)   The utf8_table... variables are now declared "const".
+    (ii)  The code for \cx, which used the "case flipping" table to upper case
+          lower case letters, now just substracts 32. This is ASCII-specific,
+          but the whole concept of \cx is ASCII-specific, so it seems
+          reasonable.
+    (iii) PCRE was using its character types table to recognize decimal and
+          hexadecimal digits in the pattern. This is silly, because it handles
+          only 0-9, a-f, and A-F, but the character types table is locale-
+          specific, which means strange things might happen. A private
+          table is now used for this - though it costs 256 bytes, a table is
+          much faster than multiple explicit tests. Of course, the standard
+          character types table is still used for matching digits in subject
+          strings against \d.
+    (iv)  Strictly, the identifier ESC_t is reserved by POSIX (all identifiers
+          ending in _t are). So I've renamed it as ESC_tee.
+. The first argument for regexec() in the POSIX wrapper should have been
+    defined as "const".
+. Changed pcretest to use malloc() for its buffers so that they can be
+    Electric Fenced for debugging.
+. There were several places in the code where, in UTF-8 mode, PCRE would try
+    to read one or more bytes before the start of the subject string. Often this
+    had no effect on PCRE's behaviour, but in some circumstances it could
+    provoke a segmentation fault.
+. A lookbehind at the start of a pattern in UTF-8 mode could also cause PCRE
+    to try to read one or more bytes before the start of the subject string.
+. A lookbehind in a pattern matched in non-UTF-8 mode on a PCRE compiled with
+    UTF-8 support could misbehave in various ways if the subject string
+    contained bytes with the 0x80 bit set and the 0x40 bit unset in a lookbehind
+    area. (PCRE was not checking for the UTF-8 mode flag, and trying to move
+    back over UTF-8 characters.)
+ Version 4.2 14-Apr-03
+ ---------------------
+. Typo "#if SUPPORT_UTF8" instead of "#ifdef SUPPORT_UTF8" fixed.
+. Changes to the building process, supplied by Ronald Landheer-Cieslak
+      [ON_WINDOWS]: new variable, "#" on non-Windows platforms
+      [NOT_ON_WINDOWS]: new variable, "#" on Windows platforms
+      [WIN_PREFIX]: new variable, "cyg" for Cygwin
+      * Makefile.in: use autoconf substitution for OBJEXT, EXEEXT, BUILD_OBJEXT
+        and BUILD_EXEEXT
+      Note: automatic setting of the BUILD variables is not yet working
+      set CPPFLAGS and BUILD_CPPFLAGS (but don't use yet) - should be used at
+        compile-time but not at link-time
+      [LINK]: use for linking executables only
+      make different versions for Windows and non-Windows
+      [LINKLIB]: new variable, copy of UNIX-style LINK, used for linking
+        libraries
+      [LINK_FOR_BUILD]: new variable
+      [OBJEXT]: use throughout
+      [EXEEXT]: use throughout
+      <winshared>: new target
+      <wininstall>: new target
+      <dftables.o>: use native compiler
+      <dftables>: use native linker
+      <install>: handle Windows platform correctly
+      <clean>: ditto
+      <check>: ditto
+      copy DLL to top builddir before testing
+    As part of these changes, -no-undefined was removed again. This was reported
+    to give trouble on HP-UX 11.0, so getting rid of it seems like a good idea
+    in any case.
+. Some tidies to get rid of compiler warnings:
+    . In the match_data structure, match_limit was an unsigned long int, whereas
+      match_call_count was an int. I've made them both unsigned long ints.
+    . In pcretest the fact that a const uschar * doesn't automatically cast to
+      a void * provoked a warning.
+    . Turning on some more compiler warnings threw up some "shadow" variables
+      and a few more missing casts.
+. If PCRE was complied with UTF-8 support, but called without the PCRE_UTF8
+    option, a class that contained a single character with a value between 128
+    and 255 (e.g. /[\xFF]/) caused PCRE to crash.
+. If PCRE was compiled with UTF-8 support, but called without the PCRE_UTF8
+    option, a class that contained several characters, but with at least one
+    whose value was between 128 and 255 caused PCRE to crash.
+ Version 4.1 12-Mar-03
+ ---------------------
+. Compiling with gcc -pedantic found a couple of places where casts were
+ needed, and a string in dftables.c that was longer than standard compilers are
+ required to support.
+. Compiling with Sun's compiler found a few more places where the code could
+ be tidied up in order to avoid warnings.
+. The variables for cross-compiling were called HOST_CC and HOST_CFLAGS; the
+ first of these names is deprecated in the latest Autoconf in favour of the name
+ CC_FOR_BUILD, because "host" is typically used to mean the system on which the
+ compiled code will be run. I can't find a reference for HOST_CFLAGS, but by
+ analogy I have changed it to CFLAGS_FOR_BUILD.
+. Added -no-undefined to the linking command in the Makefile, because this is
+ apparently helpful for Windows. To make it work, also added "-L. -lpcre" to the
+ linking step for the pcreposix library.
+. PCRE was failing to diagnose the case of two named groups with the same
+ name.
+. A problem with one of PCRE's optimizations was discovered. PCRE remembers a
+ literal character that is needed in the subject for a match, and scans along to
+ ensure that it is present before embarking on the full matching process. This
+ saves time in cases of nested unlimited repeats that are never going to match.
+ Problem: the scan can take a lot of time if the subject is very long (e.g.
+ megabytes), thus penalizing straightforward matches. It is now done only if the
+ amount of subject to be scanned is less than 1000 bytes.
+. A lesser problem with the same optimization is that it was recording the
+ first character of an anchored pattern as "needed", thus provoking a search
+ right along the subject, even when the first match of the pattern was going to
+ fail. The "needed" character is now not set for anchored patterns, unless it
+ follows something in the pattern that is of non-fixed length. Thus, it still
+ fulfils its original purpose of finding quick non-matches in cases of nested
+ unlimited repeats, but isn't used for simple anchored patterns such as /^abc/.
+ Version 4.0 17-Feb-03
+ ---------------------
+. If a comment in an extended regex that started immediately after a meta-item
+ extended to the end of string, PCRE compiled incorrect data. This could lead to
+ all kinds of weird effects. Example: /#/ was bad; /()#/ was bad; /a#/ was not.
+. Moved to autoconf 2.53 and libtool 1.4.2.
+. Perl 5.8 no longer needs "use utf8" for doing UTF-8 things. Consequently,
+ the special perltest8 script is no longer needed - all the tests can be run
+ from a single perltest script.
+. From 5.004, Perl has not included the VT character (0x0b) in the set defined
+ by \s. It has now been removed in PCRE. This means it isn't recognized as
+ whitespace in /x regexes too, which is the same as Perl. Note that the POSIX
+ class [:space:] *does* include VT, thereby creating a mess.
+. Added the class [:blank:] (a GNU extension from Perl 5.8) to match only
+ space and tab.
+. Perl 5.005 was a long time ago. It's time to amalgamate the tests that use
+ its new features into the main test script, reducing the number of scripts.
+. Perl 5.8 has changed the meaning of patterns like /a(?i)b/. Earlier versions
+ were backward compatible, and made the (?i) apply to the whole pattern, as if
+ /i were given. Now it behaves more logically, and applies the option setting
+ only to what follows. PCRE has been changed to follow suit. However, if it
+ finds options settings right at the start of the pattern, it extracts them into
+ the global options, as before. Thus, they show up in the info data.
+. Added support for the \Q...\E escape sequence. Characters in between are
+ treated as literals. This is slightly different from Perl in that $ and @ are
+ also handled as literals inside the quotes. In Perl, they will cause variable
+ interpolation. Note the following examples:
+     Pattern            PCRE matches      Perl matches
+     \Qabc$xyz\E        abc$xyz           abc followed by the contents of $xyz
+     \Qabc\$xyz\E       abc\$xyz          abc\$xyz
+     \Qabc\E\$\Qxyz\E   abc$xyz           abc$xyz
+ For compatibility with Perl, \Q...\E sequences are recognized inside character
+ classes as well as outside them.
+. Re-organized 3 code statements in pcretest to avoid "overflow in
+ floating-point constant arithmetic" warnings from a Microsoft compiler. Added a
+ (size_t) cast to one statement in pcretest and one in pcreposix to avoid
+ signed/unsigned warnings.
+. SunOS4 doesn't have strtoul(). This was used only for unpicking the -o
+ option for pcretest, so I've replaced it by a simple function that does just
+ that job.
+. pcregrep was ending with code 0 instead of 2 for the commands "pcregrep" or
+ "pcregrep -".
+. Added "possessive quantifiers" ?+, *+, ++, and {,}+ which come from Sun's
+ Java package. This provides some syntactic sugar for simple cases of what my
+ documentation calls "once-only subpatterns". A pattern such as x*+ is the same
+ as (?>x*). In other words, if what is inside (?>...) is just a single repeated
+ item, you can use this simplified notation. Note that only makes sense with
+ greedy quantifiers. Consequently, the use of the possessive quantifier forces
+ greediness, whatever the setting of the PCRE_UNGREEDY option.
+. A change of greediness default within a pattern was not taking effect at
+ the current level for patterns like /(b+(?U)a+)/. It did apply to parenthesized
+ subpatterns that followed. Patterns like /b+(?U)a+/ worked because the option
+ was abstracted outside.
+. PCRE now supports the \G assertion. It is true when the current matching
+ position is at the start point of the match. This differs from \A when the
+ starting offset is non-zero. Used with the /g option of pcretest (or similar
+ code), it works in the same way as it does for Perl's /g option. If all
+ alternatives of a regex begin with \G, the expression is anchored to the start
+ match position, and the "anchored" flag is set in the compiled expression.
+. Some bugs concerning the handling of certain option changes within patterns
+ have been fixed. These applied to options other than (?ims). For example,
+ "a(?x: b c )d" did not match "XabcdY" but did match "Xa b c dY". It should have
+ been the other way round. Some of this was related to change 7 above.
+. PCRE now gives errors for /[.x.]/ and /[=x=]/ as unsupported POSIX
+ features, as Perl does. Previously, PCRE gave the warnings only for /[[.x.]]/
+ and /[[=x=]]/. PCRE now also gives an error for /[:name:]/ because it supports
+ POSIX classes only within a class (e.g. /[[:alpha:]]/).
+. Added support for Perl's \C escape. This matches one byte, even in UTF8
+ mode. Unlike ".", it always matches newline, whatever the setting of
+ PCRE_DOTALL. However, PCRE does not permit \C to appear in lookbehind
+ assertions. Perl allows it, but it doesn't (in general) work because it can't
+ calculate the length of the lookbehind. At least, that's the case for Perl
+.8.0 - I've been told they are going to document that it doesn't work in
+ future.
+. Added an error diagnosis for escapes that PCRE does not support: these are
+ \L, \l, \N, \P, \p, \U, \u, and \X.
+. Although correctly diagnosing a missing ']' in a character class, PCRE was
+ reading past the end of the pattern in cases such as /[abcd/.
+. PCRE was getting more memory than necessary for patterns with classes that
+ contained both POSIX named classes and other characters, e.g. /[[:space:]abc/.
+. Added some code, conditional on #ifdef VPCOMPAT, to make life easier for
+ compiling PCRE for use with Virtual Pascal.
+. Small fix to the Makefile to make it work properly if the build is done
+ outside the source tree.
+. Added a new extension: a condition to go with recursion. If a conditional
+ subpattern starts with (?(R) the "true" branch is used if recursion has
+ happened, whereas the "false" branch is used only at the top level.
+. When there was a very long string of literal characters (over 255 bytes
+ without UTF support, over 250 bytes with UTF support), the computation of how
+ much memory was required could be incorrect, leading to segfaults or other
+ strange effects.
+. PCRE was incorrectly assuming anchoring (either to start of subject or to
+ start of line for a non-DOTALL pattern) when a pattern started with (.*) and
+ there was a subsequent back reference to those brackets. This meant that, for
+ example, /(.*)\d+\1/ failed to match "abc123bc". Unfortunately, it isn't
+ possible to check for precisely this case. All we can do is abandon the
+ optimization if .* occurs inside capturing brackets when there are any back
+ references whatsoever. (See below for a better fix that came later.)
+. The handling of the optimization for finding the first character of a
+ non-anchored pattern, and for finding a character that is required later in the
+ match were failing in some cases. This didn't break the matching; it just
+ failed to optimize when it could. The way this is done has been re-implemented.
+. Fixed typo in error message for invalid (?R item (it said "(?p").
+. Added a new feature that provides some of the functionality that Perl
+ provides with (?{...}). The facility is termed a "callout". The way it is done
+ in PCRE is for the caller to provide an optional function, by setting
+ pcre_callout to its entry point. Like pcre_malloc and pcre_free, this is a
+ global variable. By default it is unset, which disables all calling out. To get
+ the function called, the regex must include (?C) at appropriate points. This
+ is, in fact, equivalent to (?C0), and any number <= 255 may be given with (?C).
+ This provides a means of identifying different callout points. When PCRE
+ reaches such a point in the regex, if pcre_callout has been set, the external
+ function is called. It is provided with data in a structure called
+ pcre_callout_block, which is defined in pcre.h. If the function returns 0,
+ matching continues; if it returns a non-zero value, the match at the current
+ point fails. However, backtracking will occur if possible. [This was changed
+ later and other features added - see item 49 below.]
+. pcretest is upgraded to test the callout functionality. It provides a
+ callout function that displays information. By default, it shows the start of
+ the match and the current position in the text. There are some new data escapes
+ to vary what happens:
+     \C+         in addition, show current contents of captured substrings
+     \C-         do not supply a callout function
+     \C!n        return 1 when callout number n is reached
+     \C!n!m      return 1 when callout number n is reached for the mth time
+. If pcregrep was called with the -l option and just a single file name, it
+ output "<stdin>" if a match was found, instead of the file name.
+. Improve the efficiency of the POSIX API to PCRE. If the number of capturing
+ slots is less than POSIX_MALLOC_THRESHOLD, use a block on the stack to pass to
+ pcre_exec(). This saves a malloc/free per call. The default value of
+ POSIX_MALLOC_THRESHOLD is 10; it can be changed by --with-posix-malloc-threshold
+ when configuring.
+. The default maximum size of a compiled pattern is 64K. There have been a
+ few cases of people hitting this limit. The code now uses macros to handle the
+ storing of links as offsets within the compiled pattern. It defaults to 2-byte
+ links, but this can be changed to 3 or 4 bytes by --with-link-size when
+ configuring. Tests 2 and 5 work only with 2-byte links because they output
+ debugging information about compiled patterns.
+. Internal code re-arrangements:
+ (a) Moved the debugging function for printing out a compiled regex into
+     its own source file (printint.c) and used #include to pull it into
+     pcretest.c and, when DEBUG is defined, into pcre.c, instead of having two
+     separate copies.
+ (b) Defined the list of op-code names for debugging as a macro in
+     internal.h so that it is next to the definition of the opcodes.
+ (c) Defined a table of op-code lengths for simpler skipping along compiled
+     code. This is again a macro in internal.h so that it is next to the
+     definition of the opcodes.
+. Added support for recursive calls to individual subpatterns, along the
+ lines of Robin Houston's patch (but implemented somewhat differently).
+. Further mods to the Makefile to help Win32. Also, added code to pcregrep to
+ allow it to read and process whole directories in Win32. This code was
+ contributed by Lionel Fourquaux; it has not been tested by me.
+. Added support for named subpatterns. The Python syntax (?P<name>...) is
+ used to name a group. Names consist of alphanumerics and underscores, and must
+ be unique. Back references use the syntax (?P=name) and recursive calls use
+ (?P>name) which is a PCRE extension to the Python extension. Groups still have
+ numbers. The function pcre_fullinfo() can be used after compilation to extract
+ a name/number map. There are three relevant calls:
+   PCRE_INFO_NAMEENTRYSIZE        yields the size of each entry in the map
+   PCRE_INFO_NAMECOUNT            yields the number of entries
+   PCRE_INFO_NAMETABLE            yields a pointer to the map.
+ The map is a vector of fixed-size entries. The size of each entry depends on
+ the length of the longest name used. The first two bytes of each entry are the
+ group number, most significant byte first. There follows the corresponding
+ name, zero terminated. The names are in alphabetical order.
+. Make the maximum literal string in the compiled code 250 for the non-UTF-8
+ case instead of 255. Making it the same both with and without UTF-8 support
+ means that the same test output works with both.
+. There was a case of malloc(0) in the POSIX testing code in pcretest. Avoid
+ calling malloc() with a zero argument.
+. Change 25 above had to resort to a heavy-handed test for the .* anchoring
+ optimization. I've improved things by keeping a bitmap of backreferences with
+ numbers 1-31 so that if .* occurs inside capturing brackets that are not in
+ fact referenced, the optimization can be applied. It is unlikely that a
+ relevant occurrence of .* (i.e. one which might indicate anchoring or forcing
+ the match to follow \n) will appear inside brackets with a number greater than
+, but if it does, any back reference > 31 suppresses the optimization.
+. Added a new compile-time option PCRE_NO_AUTO_CAPTURE. This has the effect
+ of disabling numbered capturing parentheses. Any opening parenthesis that is
+ not followed by ? behaves as if it were followed by ?: but named parentheses
+ can still be used for capturing (and they will acquire numbers in the usual
+ way).
+. Redesigned the return codes from the match() function into yes/no/error so
+ that errors can be passed back from deep inside the nested calls. A malloc
+ failure while inside a recursive subpattern call now causes the
+ PCRE_ERROR_NOMEMORY return instead of quietly going wrong.
+. It is now possible to set a limit on the number of times the match()
+ function is called in a call to pcre_exec(). This facility makes it possible to
+ limit the amount of recursion and backtracking, though not in a directly
+ obvious way, because the match() function is used in a number of different
+ circumstances. The count starts from zero for each position in the subject
+ string (for non-anchored patterns). The default limit is, for compatibility, a
+ large number, namely 10 000 000. You can change this in two ways:
+ (a) When configuring PCRE before making, you can use --with-match-limit=n
+     to set a default value for the compiled library.
+ (b) For each call to pcre_exec(), you can pass a pcre_extra block in which
+     a different value is set. See 45 below.
+ If the limit is exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT.
+. Added a new function pcre_config(int, void *) to enable run-time extraction
+ of things that can be changed at compile time. The first argument specifies
+ what is wanted and the second points to where the information is to be placed.
+ The current list of available information is:
+   PCRE_CONFIG_UTF8
+ The output is an integer that is set to one if UTF-8 support is available;
+ otherwise it is set to zero.
+   PCRE_CONFIG_NEWLINE
+ The output is an integer that it set to the value of the code that is used for
+ newline. It is either LF (10) or CR (13).
+   PCRE_CONFIG_LINK_SIZE
+ The output is an integer that contains the number of bytes used for internal
+ linkage in compiled expressions. The value is 2, 3, or 4. See item 32 above.
+   PCRE_CONFIG_POSIX_MALLOC_THRESHOLD
+ The output is an integer that contains the threshold above which the POSIX
+ interface uses malloc() for output vectors. See item 31 above.
+   PCRE_CONFIG_MATCH_LIMIT
+ The output is an unsigned integer that contains the default limit of the number
+ of match() calls in a pcre_exec() execution. See 42 above.
+. pcretest has been upgraded by the addition of the -C option. This causes it
+ to extract all the available output from the new pcre_config() function, and to
+ output it. The program then exits immediately.
+. A need has arisen to pass over additional data with calls to pcre_exec() in
+ order to support additional features. One way would have been to define
+ pcre_exec2() (for example) with extra arguments, but this would not have been
+ extensible, and would also have required all calls to the original function to
+ be mapped to the new one. Instead, I have chosen to extend the mechanism that
+ is used for passing in "extra" data from pcre_study().
+ The pcre_extra structure is now exposed and defined in pcre.h. It currently
+ contains the following fields:
+   flags         a bitmap indicating which of the following fields are set
+   study_data    opaque data from pcre_study()
+   match_limit   a way of specifying a limit on match() calls for a specific
+                   call to pcre_exec()
+   callout_data  data for callouts (see 49 below)
+ The flag bits are also defined in pcre.h, and are
+   PCRE_EXTRA_STUDY_DATA
+   PCRE_EXTRA_MATCH_LIMIT
+   PCRE_EXTRA_CALLOUT_DATA
+ The pcre_study() function now returns one of these new pcre_extra blocks, with
+ the actual study data pointed to by the study_data field, and the
+ PCRE_EXTRA_STUDY_DATA flag set. This can be passed directly to pcre_exec() as
+ before. That is, this change is entirely upwards-compatible and requires no
+ change to existing code.
+ If you want to pass in additional data to pcre_exec(), you can either place it
+ in a pcre_extra block provided by pcre_study(), or create your own pcre_extra
+ block.
+. pcretest has been extended to test the PCRE_EXTRA_MATCH_LIMIT feature. If a
+ data string contains the escape sequence \M, pcretest calls pcre_exec() several
+ times with different match limits, until it finds the minimum value needed for
+ pcre_exec() to complete. The value is then output. This can be instructive; for
+ most simple matches the number is quite small, but for pathological cases it
+ gets very large very quickly.
+. There's a new option for pcre_fullinfo() called PCRE_INFO_STUDYSIZE. It
+ returns the size of the data block pointed to by the study_data field in a
+ pcre_extra block, that is, the value that was passed as the argument to
+ pcre_malloc() when PCRE was getting memory in which to place the information
+ created by pcre_study(). The fourth argument should point to a size_t variable.
+ pcretest has been extended so that this information is shown after a successful
+ pcre_study() call when information about the compiled regex is being displayed.
+. Cosmetic change to Makefile: there's no need to have / after $(DESTDIR)
+ because what follows is always an absolute path. (Later: it turns out that this
+ is more than cosmetic for MinGW, because it doesn't like empty path
+ components.)
+. Some changes have been made to the callout feature (see 28 above):
+ (i)  A callout function now has three choices for what it returns:
+ =>  success, carry on matching
+      > 0  =>  failure at this point, but backtrack if possible
+      < 0  =>  serious error, return this value from pcre_exec()
+      Negative values should normally be chosen from the set of PCRE_ERROR_xxx
+      values. In particular, returning PCRE_ERROR_NOMATCH forces a standard
+      "match failed" error. The error number PCRE_ERROR_CALLOUT is reserved for
+      use by callout functions. It will never be used by PCRE itself.
+ (ii) The pcre_extra structure (see 45 above) has a void * field called
+      callout_data, with corresponding flag bit PCRE_EXTRA_CALLOUT_DATA. The
+      pcre_callout_block structure has a field of the same name. The contents of
+      the field passed in the pcre_extra structure are passed to the callout
+      function in the corresponding field in the callout block. This makes it
+      easier to use the same callout-containing regex from multiple threads. For
+      testing, the pcretest program has a new data escape
+        \C*n        pass the number n (may be negative) as callout_data
+      If the callout function in pcretest receives a non-zero value as
+      callout_data, it returns that value.
+. Makefile wasn't handling CFLAGS properly when compiling dftables. Also,
+ there were some redundant $(CFLAGS) in commands that are now specified as
+ $(LINK), which already includes $(CFLAGS).
+. Extensions to UTF-8 support are listed below. These all apply when (a) PCRE
+ has been compiled with UTF-8 support *and* pcre_compile() has been compiled
+ with the PCRE_UTF8 flag. Patterns that are compiled without that flag assume
+ one-byte characters throughout. Note that case-insensitive matching applies
+ only to characters whose values are less than 256. PCRE doesn't support the
+ notion of cases for higher-valued characters.
+ (i)   A character class whose characters are all within 0-255 is handled as
+       a bit map, and the map is inverted for negative classes. Previously, a
+       character > 255 always failed to match such a class; however it should
+       match if the class was a negative one (e.g. [^ab]). This has been fixed.
+ (ii)  A negated character class with a single character < 255 is coded as
+       "not this character" (OP_NOT). This wasn't working properly when the test
+       character was multibyte, either singly or repeated.
+ (iii) Repeats of multibyte characters are now handled correctly in UTF-8
+       mode, for example: \x{100}{2,3}.
+ (iv)  The character escapes \b, \B, \d, \D, \s, \S, \w, and \W (either
+       singly or repeated) now correctly test multibyte characters. However,
+       PCRE doesn't recognize any characters with values greater than 255 as
+       digits, spaces, or word characters. Such characters always match \D, \S,
+       and \W, and never match \d, \s, or \w.
+ (v)   Classes may now contain characters and character ranges with values
+       greater than 255. For example: [ab\x{100}-\x{400}].
+ (vi)  pcregrep now has a --utf-8 option (synonym -u) which makes it call
+       PCRE in UTF-8 mode.
+. The info request value PCRE_INFO_FIRSTCHAR has been renamed
+ PCRE_INFO_FIRSTBYTE because it is a byte value. However, the old name is
+ retained for backwards compatibility. (Note that LASTLITERAL is also a byte
+ value.)
+. The single man page has become too large. I have therefore split it up into
+ a number of separate man pages. These also give rise to individual HTML pages;
+ these are now put in a separate directory, and there is an index.html page that
+ lists them all. Some hyperlinking between the pages has been installed.
+. Added convenience functions for handling named capturing parentheses.
+. Unknown escapes inside character classes (e.g. [\M]) and escapes that
+ aren't interpreted therein (e.g. [\C]) are literals in Perl. This is now also
+ true in PCRE, except when the PCRE_EXTENDED option is set, in which case they
+ are faulted.
+. Introduced HOST_CC and HOST_CFLAGS which can be set in the environment when
+ calling configure. These values are used when compiling the dftables.c program
+ which is run to generate the source of the default character tables. They
+ default to the values of CC and CFLAGS. If you are cross-compiling PCRE,
+ you will need to set these values.
+. Updated the building process for Windows DLL, as provided by Fred Cox.
+ Version 3.9 02-Jan-02
+ ---------------------
+. A bit of extraneous text had somehow crept into the pcregrep documentation.
+. If --disable-static was given, the building process failed when trying to
+ build pcretest and pcregrep. (For some reason it was using libtool to compile
+ them, which is not right, as they aren't part of the library.)
+ Version 3.8 18-Dec-01
+ ---------------------
+. The experimental UTF-8 code was completely screwed up. It was packing the
+ bytes in the wrong order. How dumb can you get?
  Version 3.7 29-Oct-01
  ---------------------
-Line 8 
 Version 3.7 29-Oct-01
+Line 749 
 Version 3.7 29-Oct-01
  This caused pcretest, when used on the test data, to segfault. Unfortunately,
  this didn't happen under Solaris 8, where I normally test things.
+. The Makefile had to be changed to make it work on BSD systems, where 'make'
+ doesn't seem to recognize that ./xxx and xxx are the same file. (This entry
+ isn't in ChangeLog distributed with 3.7 because I forgot when I hastily made
+ this fix an hour or so after the initial 3.7 release.)
  Version 3.6 23-Oct-01
  ---------------------

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