From 582b500cd996c96054615870fd13d6ab0ea77428 Mon Sep 17 00:00:00 2001 From: Jay Berkenbilt Date: Sat, 10 Oct 2009 15:10:05 +0000 Subject: start integrating windows port git-svn-id: svn+q:///qpdf/trunk@757 71b93d88-0707-0410-a8cf-f5a4172ac649 --- external-libs/pcre/doc/pcrebuild.3 | 145 +++++++++++++++++++++++++++++++++++++ 1 file changed, 145 insertions(+) create mode 100644 external-libs/pcre/doc/pcrebuild.3 (limited to 'external-libs/pcre/doc/pcrebuild.3') diff --git a/external-libs/pcre/doc/pcrebuild.3 b/external-libs/pcre/doc/pcrebuild.3 new file mode 100644 index 00000000..a91782c0 --- /dev/null +++ b/external-libs/pcre/doc/pcrebuild.3 @@ -0,0 +1,145 @@ +.TH PCRE 3 +.SH NAME +PCRE - Perl-compatible regular expressions +.SH PCRE BUILD-TIME OPTIONS +.rs +.sp +This document describes the optional features of PCRE that can be selected when +the library is compiled. They are all selected, or deselected, by providing +options to the \fBconfigure\fR script which is run before the \fBmake\fR +command. The complete list of options for \fBconfigure\fR (which includes the +standard ones such as the selection of the installation directory) can be +obtained by running + + ./configure --help + +The following sections describe certain options whose names begin with --enable +or --disable. These settings specify changes to the defaults for the +\fBconfigure\fR command. Because of the way that \fBconfigure\fR works, +--enable and --disable always come in pairs, so the complementary option always +exists as well, but as it specifies the default, it is not described. + +.SH UTF-8 SUPPORT +.rs +.sp +To build PCRE with support for UTF-8 character strings, add + + --enable-utf8 + +to the \fBconfigure\fR command. Of itself, this does not make PCRE treat +strings as UTF-8. As well as compiling PCRE with this option, you also have +have to set the PCRE_UTF8 option when you call the \fBpcre_compile()\fR +function. + +.SH CODE VALUE OF NEWLINE +.rs +.sp +By default, PCRE treats character 10 (linefeed) as the newline character. This +is the normal newline character on Unix-like systems. You can compile PCRE to +use character 13 (carriage return) instead by adding + + --enable-newline-is-cr + +to the \fBconfigure\fR command. For completeness there is also a +--enable-newline-is-lf option, which explicitly specifies linefeed as the +newline character. + +.SH BUILDING SHARED AND STATIC LIBRARIES +.rs +.sp +The PCRE building process uses \fBlibtool\fR to build both shared and static +Unix libraries by default. You can suppress one of these by adding one of + + --disable-shared + --disable-static + +to the \fBconfigure\fR command, as required. + +.SH POSIX MALLOC USAGE +.rs +.sp +When PCRE is called through the POSIX interface (see the \fBpcreposix\fR +documentation), additional working storage is required for holding the pointers +to capturing substrings because PCRE requires three integers per substring, +whereas the POSIX interface provides only two. If the number of expected +substrings is small, the wrapper function uses space on the stack, because this +is faster than using \fBmalloc()\fR for each call. The default threshold above +which the stack is no longer used is 10; it can be changed by adding a setting +such as + + --with-posix-malloc-threshold=20 + +to the \fBconfigure\fR command. + +.SH LIMITING PCRE RESOURCE USAGE +.rs +.sp +Internally, PCRE has a function called \fBmatch()\fR which it calls repeatedly +(possibly recursively) when performing a matching operation. By limiting the +number of times this function may be called, a limit can be placed on the +resources used by a single call to \fBpcre_exec()\fR. The limit can be changed +at run time, as described in the \fBpcreapi\fR documentation. The default is 10 +million, but this can be changed by adding a setting such as + + --with-match-limit=500000 + +to the \fBconfigure\fR command. + +.SH HANDLING VERY LARGE PATTERNS +.rs +.sp +Within a compiled pattern, offset values are used to point from one part to +another (for example, from an opening parenthesis to an alternation +metacharacter). By default two-byte values are used for these offsets, leading +to a maximum size for a compiled pattern of around 64K. This is sufficient to +handle all but the most gigantic patterns. Nevertheless, some people do want to +process enormous patterns, so it is possible to compile PCRE to use three-byte +or four-byte offsets by adding a setting such as + + --with-link-size=3 + +to the \fBconfigure\fR command. The value given must be 2, 3, or 4. Using +longer offsets slows down the operation of PCRE because it has to load +additional bytes when handling them. + +If you build PCRE with an increased link size, test 2 (and test 5 if you are +using UTF-8) will fail. Part of the output of these tests is a representation +of the compiled pattern, and this changes with the link size. + +.SH AVOIDING EXCESSIVE STACK USAGE +.rs +.sp +PCRE implements backtracking while matching by making recursive calls to an +internal function called \fBmatch()\fR. In environments where the size of the +stack is limited, this can severely limit PCRE's operation. (The Unix +environment does not usually suffer from this problem.) An alternative approach +that uses memory from the heap to remember data, instead of using recursive +function calls, has been implemented to work round this problem. If you want to +build a version of PCRE that works this way, add + + --disable-stack-for-recursion + +to the \fBconfigure\fR command. With this configuration, PCRE will use the +\fBpcre_stack_malloc\fR and \fBpcre_stack_free\fR variables to call memory +management functions. Separate functions are provided because the usage is very +predictable: the block sizes requested are always the same, and the blocks are +always freed in reverse order. A calling program might be able to implement +optimized functions that perform better than the standard \fBmalloc()\fR and +\fBfree()\fR functions. PCRE runs noticeably more slowly when built in this +way. + +.SH USING EBCDIC CODE +.rs +.sp +PCRE assumes by default that it will run in an environment where the character +code is ASCII (or UTF-8, which is a superset of ASCII). PCRE can, however, be +compiled to run in an EBCDIC environment by adding + + --enable-ebcdic + +to the \fBconfigure\fR command. + +.in 0 +Last updated: 09 December 2003 +.br +Copyright (c) 1997-2003 University of Cambridge. -- cgit v1.2.3-70-g09d2