602 lines
25 KiB
HTML
602 lines
25 KiB
HTML
<html>
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<head>
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<title>pcre2build specification</title>
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</head>
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<body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
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<h1>pcre2build man page</h1>
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<p>
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Return to the <a href="index.html">PCRE2 index page</a>.
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</p>
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<p>
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This page is part of the PCRE2 HTML documentation. It was generated
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automatically from the original man page. If there is any nonsense in it,
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please consult the man page, in case the conversion went wrong.
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<br>
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<ul>
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<li><a name="TOC1" href="#SEC1">BUILDING PCRE2</a>
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<li><a name="TOC2" href="#SEC2">PCRE2 BUILD-TIME OPTIONS</a>
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<li><a name="TOC3" href="#SEC3">BUILDING 8-BIT, 16-BIT AND 32-BIT LIBRARIES</a>
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<li><a name="TOC4" href="#SEC4">BUILDING SHARED AND STATIC LIBRARIES</a>
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<li><a name="TOC5" href="#SEC5">UNICODE AND UTF SUPPORT</a>
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<li><a name="TOC6" href="#SEC6">DISABLING THE USE OF \C</a>
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<li><a name="TOC7" href="#SEC7">JUST-IN-TIME COMPILER SUPPORT</a>
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<li><a name="TOC8" href="#SEC8">NEWLINE RECOGNITION</a>
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<li><a name="TOC9" href="#SEC9">WHAT \R MATCHES</a>
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<li><a name="TOC10" href="#SEC10">HANDLING VERY LARGE PATTERNS</a>
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<li><a name="TOC11" href="#SEC11">LIMITING PCRE2 RESOURCE USAGE</a>
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<li><a name="TOC12" href="#SEC12">CREATING CHARACTER TABLES AT BUILD TIME</a>
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<li><a name="TOC13" href="#SEC13">USING EBCDIC CODE</a>
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<li><a name="TOC14" href="#SEC14">PCRE2GREP SUPPORT FOR EXTERNAL SCRIPTS</a>
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<li><a name="TOC15" href="#SEC15">PCRE2GREP OPTIONS FOR COMPRESSED FILE SUPPORT</a>
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<li><a name="TOC16" href="#SEC16">PCRE2GREP BUFFER SIZE</a>
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<li><a name="TOC17" href="#SEC17">PCRE2TEST OPTION FOR LIBREADLINE SUPPORT</a>
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<li><a name="TOC18" href="#SEC18">INCLUDING DEBUGGING CODE</a>
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<li><a name="TOC19" href="#SEC19">DEBUGGING WITH VALGRIND SUPPORT</a>
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<li><a name="TOC20" href="#SEC20">CODE COVERAGE REPORTING</a>
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<li><a name="TOC21" href="#SEC21">DISABLING THE Z AND T FORMATTING MODIFIERS</a>
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<li><a name="TOC22" href="#SEC22">SUPPORT FOR FUZZERS</a>
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<li><a name="TOC23" href="#SEC23">OBSOLETE OPTION</a>
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<li><a name="TOC24" href="#SEC24">SEE ALSO</a>
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<li><a name="TOC25" href="#SEC25">AUTHOR</a>
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<li><a name="TOC26" href="#SEC26">REVISION</a>
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</ul>
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<br><a name="SEC1" href="#TOC1">BUILDING PCRE2</a><br>
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<P>
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PCRE2 is distributed with a <b>configure</b> script that can be used to build
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the library in Unix-like environments using the applications known as
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Autotools. Also in the distribution are files to support building using
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<b>CMake</b> instead of <b>configure</b>. The text file
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<a href="README.txt"><b>README</b></a>
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contains general information about building with Autotools (some of which is
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repeated below), and also has some comments about building on various operating
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systems. There is a lot more information about building PCRE2 without using
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Autotools (including information about using <b>CMake</b> and building "by
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hand") in the text file called
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<a href="NON-AUTOTOOLS-BUILD.txt"><b>NON-AUTOTOOLS-BUILD</b>.</a>
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You should consult this file as well as the
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<a href="README.txt"><b>README</b></a>
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file if you are building in a non-Unix-like environment.
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</P>
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<br><a name="SEC2" href="#TOC1">PCRE2 BUILD-TIME OPTIONS</a><br>
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<P>
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The rest of this document describes the optional features of PCRE2 that can be
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selected when the library is compiled. It assumes use of the <b>configure</b>
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script, where the optional features are selected or deselected by providing
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options to <b>configure</b> before running the <b>make</b> command. However, the
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same options can be selected in both Unix-like and non-Unix-like environments
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if you are using <b>CMake</b> instead of <b>configure</b> to build PCRE2.
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</P>
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<P>
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If you are not using Autotools or <b>CMake</b>, option selection can be done by
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editing the <b>config.h</b> file, or by passing parameter settings to the
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compiler, as described in
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<a href="NON-AUTOTOOLS-BUILD.txt"><b>NON-AUTOTOOLS-BUILD</b>.</a>
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</P>
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<P>
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The complete list of options for <b>configure</b> (which includes the standard
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ones such as the selection of the installation directory) can be obtained by
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running
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<pre>
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./configure --help
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</pre>
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The following sections include descriptions of "on/off" options whose names
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begin with --enable or --disable. Because of the way that <b>configure</b>
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works, --enable and --disable always come in pairs, so the complementary option
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always exists as well, but as it specifies the default, it is not described.
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Options that specify values have names that start with --with. At the end of a
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<b>configure</b> run, a summary of the configuration is output.
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</P>
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<br><a name="SEC3" href="#TOC1">BUILDING 8-BIT, 16-BIT AND 32-BIT LIBRARIES</a><br>
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<P>
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By default, a library called <b>libpcre2-8</b> is built, containing functions
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that take string arguments contained in arrays of bytes, interpreted either as
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single-byte characters, or UTF-8 strings. You can also build two other
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libraries, called <b>libpcre2-16</b> and <b>libpcre2-32</b>, which process
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strings that are contained in arrays of 16-bit and 32-bit code units,
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respectively. These can be interpreted either as single-unit characters or
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UTF-16/UTF-32 strings. To build these additional libraries, add one or both of
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the following to the <b>configure</b> command:
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<pre>
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--enable-pcre2-16
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--enable-pcre2-32
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</pre>
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If you do not want the 8-bit library, add
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<pre>
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--disable-pcre2-8
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</pre>
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as well. At least one of the three libraries must be built. Note that the POSIX
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wrapper is for the 8-bit library only, and that <b>pcre2grep</b> is an 8-bit
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program. Neither of these are built if you select only the 16-bit or 32-bit
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libraries.
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</P>
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<br><a name="SEC4" href="#TOC1">BUILDING SHARED AND STATIC LIBRARIES</a><br>
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<P>
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The Autotools PCRE2 building process uses <b>libtool</b> to build both shared
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and static libraries by default. You can suppress an unwanted library by adding
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one of
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<pre>
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--disable-shared
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--disable-static
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</pre>
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to the <b>configure</b> command.
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</P>
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<br><a name="SEC5" href="#TOC1">UNICODE AND UTF SUPPORT</a><br>
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<P>
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By default, PCRE2 is built with support for Unicode and UTF character strings.
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To build it without Unicode support, add
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<pre>
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--disable-unicode
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</pre>
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to the <b>configure</b> command. This setting applies to all three libraries. It
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is not possible to build one library with Unicode support, and another without,
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in the same configuration.
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</P>
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<P>
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Of itself, Unicode support does not make PCRE2 treat strings as UTF-8, UTF-16
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or UTF-32. To do that, applications that use the library can set the PCRE2_UTF
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option when they call <b>pcre2_compile()</b> to compile a pattern.
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Alternatively, patterns may be started with (*UTF) unless the application has
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locked this out by setting PCRE2_NEVER_UTF.
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</P>
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<P>
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UTF support allows the libraries to process character code points up to
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0x10ffff in the strings that they handle. Unicode support also gives access to
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the Unicode properties of characters, using pattern escapes such as \P, \p,
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and \X. Only the general category properties such as <i>Lu</i> and <i>Nd</i> are
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supported. Details are given in the
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<a href="pcre2pattern.html"><b>pcre2pattern</b></a>
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documentation.
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</P>
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<P>
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Pattern escapes such as \d and \w do not by default make use of Unicode
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properties. The application can request that they do by setting the PCRE2_UCP
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option. Unless the application has set PCRE2_NEVER_UCP, a pattern may also
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request this by starting with (*UCP).
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</P>
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<br><a name="SEC6" href="#TOC1">DISABLING THE USE OF \C</a><br>
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<P>
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The \C escape sequence, which matches a single code unit, even in a UTF mode,
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can cause unpredictable behaviour because it may leave the current matching
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point in the middle of a multi-code-unit character. The application can lock it
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out by setting the PCRE2_NEVER_BACKSLASH_C option when calling
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<b>pcre2_compile()</b>. There is also a build-time option
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<pre>
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--enable-never-backslash-C
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</pre>
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(note the upper case C) which locks out the use of \C entirely.
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</P>
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<br><a name="SEC7" href="#TOC1">JUST-IN-TIME COMPILER SUPPORT</a><br>
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<P>
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Just-in-time (JIT) compiler support is included in the build by specifying
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<pre>
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--enable-jit
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</pre>
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This support is available only for certain hardware architectures. If this
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option is set for an unsupported architecture, a building error occurs.
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If in doubt, use
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<pre>
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--enable-jit=auto
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</pre>
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which enables JIT only if the current hardware is supported. You can check
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if JIT is enabled in the configuration summary that is output at the end of a
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<b>configure</b> run. If you are enabling JIT under SELinux you may also want to
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add
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<pre>
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--enable-jit-sealloc
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</pre>
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which enables the use of an execmem allocator in JIT that is compatible with
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SELinux. This has no effect if JIT is not enabled. See the
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<a href="pcre2jit.html"><b>pcre2jit</b></a>
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documentation for a discussion of JIT usage. When JIT support is enabled,
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pcre2grep automatically makes use of it, unless you add
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<pre>
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--disable-pcre2grep-jit
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</pre>
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to the "configure" command.
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</P>
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<br><a name="SEC8" href="#TOC1">NEWLINE RECOGNITION</a><br>
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<P>
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By default, PCRE2 interprets the linefeed (LF) character as indicating the end
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of a line. This is the normal newline character on Unix-like systems. You can
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compile PCRE2 to use carriage return (CR) instead, by adding
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<pre>
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--enable-newline-is-cr
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</pre>
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to the <b>configure</b> command. There is also an --enable-newline-is-lf option,
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which explicitly specifies linefeed as the newline character.
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</P>
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<P>
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Alternatively, you can specify that line endings are to be indicated by the
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two-character sequence CRLF (CR immediately followed by LF). If you want this,
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add
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<pre>
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--enable-newline-is-crlf
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</pre>
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to the <b>configure</b> command. There is a fourth option, specified by
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<pre>
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--enable-newline-is-anycrlf
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</pre>
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which causes PCRE2 to recognize any of the three sequences CR, LF, or CRLF as
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indicating a line ending. A fifth option, specified by
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<pre>
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--enable-newline-is-any
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</pre>
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causes PCRE2 to recognize any Unicode newline sequence. The Unicode newline
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sequences are the three just mentioned, plus the single characters VT (vertical
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tab, U+000B), FF (form feed, U+000C), NEL (next line, U+0085), LS (line
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separator, U+2028), and PS (paragraph separator, U+2029). The final option is
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<pre>
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--enable-newline-is-nul
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</pre>
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which causes NUL (binary zero) to be set as the default line-ending character.
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</P>
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<P>
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Whatever default line ending convention is selected when PCRE2 is built can be
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overridden by applications that use the library. At build time it is
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recommended to use the standard for your operating system.
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</P>
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<br><a name="SEC9" href="#TOC1">WHAT \R MATCHES</a><br>
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<P>
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By default, the sequence \R in a pattern matches any Unicode newline sequence,
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independently of what has been selected as the line ending sequence. If you
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specify
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<pre>
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--enable-bsr-anycrlf
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</pre>
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the default is changed so that \R matches only CR, LF, or CRLF. Whatever is
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selected when PCRE2 is built can be overridden by applications that use the
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library.
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</P>
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<br><a name="SEC10" href="#TOC1">HANDLING VERY LARGE PATTERNS</a><br>
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<P>
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Within a compiled pattern, offset values are used to point from one part to
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another (for example, from an opening parenthesis to an alternation
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metacharacter). By default, in the 8-bit and 16-bit libraries, two-byte values
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are used for these offsets, leading to a maximum size for a compiled pattern of
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around 64 thousand code units. This is sufficient to handle all but the most
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gigantic patterns. Nevertheless, some people do want to process truly enormous
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patterns, so it is possible to compile PCRE2 to use three-byte or four-byte
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offsets by adding a setting such as
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<pre>
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--with-link-size=3
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</pre>
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to the <b>configure</b> command. The value given must be 2, 3, or 4. For the
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16-bit library, a value of 3 is rounded up to 4. In these libraries, using
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longer offsets slows down the operation of PCRE2 because it has to load
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additional data when handling them. For the 32-bit library the value is always
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4 and cannot be overridden; the value of --with-link-size is ignored.
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</P>
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<br><a name="SEC11" href="#TOC1">LIMITING PCRE2 RESOURCE USAGE</a><br>
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<P>
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The <b>pcre2_match()</b> function increments a counter each time it goes round
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its main loop. Putting a limit on this counter controls the amount of computing
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resource used by a single call to <b>pcre2_match()</b>. The limit can be changed
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at run time, as described in the
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<a href="pcre2api.html"><b>pcre2api</b></a>
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documentation. The default is 10 million, but this can be changed by adding a
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setting such as
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<pre>
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--with-match-limit=500000
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</pre>
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to the <b>configure</b> command. This setting also applies to the
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<b>pcre2_dfa_match()</b> matching function, and to JIT matching (though the
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counting is done differently).
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</P>
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<P>
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The <b>pcre2_match()</b> function starts out using a 20KiB vector on the system
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stack to record backtracking points. The more nested backtracking points there
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are (that is, the deeper the search tree), the more memory is needed. If the
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initial vector is not large enough, heap memory is used, up to a certain limit,
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which is specified in kibibytes (units of 1024 bytes). The limit can be changed
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at run time, as described in the
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<a href="pcre2api.html"><b>pcre2api</b></a>
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documentation. The default limit (in effect unlimited) is 20 million. You can
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change this by a setting such as
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<pre>
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--with-heap-limit=500
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</pre>
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which limits the amount of heap to 500 KiB. This limit applies only to
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interpretive matching in <b>pcre2_match()</b> and <b>pcre2_dfa_match()</b>, which
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may also use the heap for internal workspace when processing complicated
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patterns. This limit does not apply when JIT (which has its own memory
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arrangements) is used.
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</P>
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<P>
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You can also explicitly limit the depth of nested backtracking in the
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<b>pcre2_match()</b> interpreter. This limit defaults to the value that is set
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for --with-match-limit. You can set a lower default limit by adding, for
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example,
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<pre>
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--with-match-limit_depth=10000
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</pre>
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to the <b>configure</b> command. This value can be overridden at run time. This
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depth limit indirectly limits the amount of heap memory that is used, but
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because the size of each backtracking "frame" depends on the number of
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capturing parentheses in a pattern, the amount of heap that is used before the
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limit is reached varies from pattern to pattern. This limit was more useful in
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versions before 10.30, where function recursion was used for backtracking.
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</P>
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<P>
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As well as applying to <b>pcre2_match()</b>, the depth limit also controls
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the depth of recursive function calls in <b>pcre2_dfa_match()</b>. These are
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used for lookaround assertions, atomic groups, and recursion within patterns.
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The limit does not apply to JIT matching.
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</P>
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<br><a name="SEC12" href="#TOC1">CREATING CHARACTER TABLES AT BUILD TIME</a><br>
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<P>
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PCRE2 uses fixed tables for processing characters whose code points are less
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than 256. By default, PCRE2 is built with a set of tables that are distributed
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in the file <i>src/pcre2_chartables.c.dist</i>. These tables are for ASCII codes
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only. If you add
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<pre>
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--enable-rebuild-chartables
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</pre>
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to the <b>configure</b> command, the distributed tables are no longer used.
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Instead, a program called <b>dftables</b> is compiled and run. This outputs the
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source for new set of tables, created in the default locale of your C run-time
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system. This method of replacing the tables does not work if you are cross
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compiling, because <b>dftables</b> is run on the local host. If you need to
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create alternative tables when cross compiling, you will have to do so "by
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hand".
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</P>
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<br><a name="SEC13" href="#TOC1">USING EBCDIC CODE</a><br>
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<P>
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PCRE2 assumes by default that it will run in an environment where the character
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code is ASCII or Unicode, which is a superset of ASCII. This is the case for
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most computer operating systems. PCRE2 can, however, be compiled to run in an
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8-bit EBCDIC environment by adding
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<pre>
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--enable-ebcdic --disable-unicode
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</pre>
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to the <b>configure</b> command. This setting implies
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--enable-rebuild-chartables. You should only use it if you know that you are in
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an EBCDIC environment (for example, an IBM mainframe operating system).
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</P>
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<P>
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It is not possible to support both EBCDIC and UTF-8 codes in the same version
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of the library. Consequently, --enable-unicode and --enable-ebcdic are mutually
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exclusive.
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</P>
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<P>
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The EBCDIC character that corresponds to an ASCII LF is assumed to have the
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value 0x15 by default. However, in some EBCDIC environments, 0x25 is used. In
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such an environment you should use
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<pre>
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--enable-ebcdic-nl25
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</pre>
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as well as, or instead of, --enable-ebcdic. The EBCDIC character for CR has the
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same value as in ASCII, namely, 0x0d. Whichever of 0x15 and 0x25 is <i>not</i>
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chosen as LF is made to correspond to the Unicode NEL character (which, in
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Unicode, is 0x85).
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</P>
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<P>
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The options that select newline behaviour, such as --enable-newline-is-cr,
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and equivalent run-time options, refer to these character values in an EBCDIC
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environment.
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</P>
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<br><a name="SEC14" href="#TOC1">PCRE2GREP SUPPORT FOR EXTERNAL SCRIPTS</a><br>
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<P>
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By default <b>pcre2grep</b> supports the use of callouts with string arguments
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within the patterns it is matching. There are two kinds: one that generates
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output using local code, and another that calls an external program or script.
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If --disable-pcre2grep-callout-fork is added to the <b>configure</b> command,
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only the first kind of callout is supported; if --disable-pcre2grep-callout is
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used, all callouts are completely ignored. For more details of <b>pcre2grep</b>
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callouts, see the
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<a href="pcre2grep.html"><b>pcre2grep</b></a>
|
|
documentation.
|
|
</P>
|
|
<br><a name="SEC15" href="#TOC1">PCRE2GREP OPTIONS FOR COMPRESSED FILE SUPPORT</a><br>
|
|
<P>
|
|
By default, <b>pcre2grep</b> reads all files as plain text. You can build it so
|
|
that it recognizes files whose names end in <b>.gz</b> or <b>.bz2</b>, and reads
|
|
them with <b>libz</b> or <b>libbz2</b>, respectively, by adding one or both of
|
|
<pre>
|
|
--enable-pcre2grep-libz
|
|
--enable-pcre2grep-libbz2
|
|
</pre>
|
|
to the <b>configure</b> command. These options naturally require that the
|
|
relevant libraries are installed on your system. Configuration will fail if
|
|
they are not.
|
|
</P>
|
|
<br><a name="SEC16" href="#TOC1">PCRE2GREP BUFFER SIZE</a><br>
|
|
<P>
|
|
<b>pcre2grep</b> uses an internal buffer to hold a "window" on the file it is
|
|
scanning, in order to be able to output "before" and "after" lines when it
|
|
finds a match. The default starting size of the buffer is 20KiB. The buffer
|
|
itself is three times this size, but because of the way it is used for holding
|
|
"before" lines, the longest line that is guaranteed to be processable is the
|
|
notional buffer size. If a longer line is encountered, <b>pcre2grep</b>
|
|
automatically expands the buffer, up to a specified maximum size, whose default
|
|
is 1MiB or the starting size, whichever is the larger. You can change the
|
|
default parameter values by adding, for example,
|
|
<pre>
|
|
--with-pcre2grep-bufsize=51200
|
|
--with-pcre2grep-max-bufsize=2097152
|
|
</pre>
|
|
to the <b>configure</b> command. The caller of \fPpcre2grep\fP can override
|
|
these values by using --buffer-size and --max-buffer-size on the command line.
|
|
</P>
|
|
<br><a name="SEC17" href="#TOC1">PCRE2TEST OPTION FOR LIBREADLINE SUPPORT</a><br>
|
|
<P>
|
|
If you add one of
|
|
<pre>
|
|
--enable-pcre2test-libreadline
|
|
--enable-pcre2test-libedit
|
|
</pre>
|
|
to the <b>configure</b> command, <b>pcre2test</b> is linked with the
|
|
<b>libreadline</b> or<b>libedit</b> library, respectively, and when its input is
|
|
from a terminal, it reads it using the <b>readline()</b> function. This provides
|
|
line-editing and history facilities. Note that <b>libreadline</b> is
|
|
GPL-licensed, so if you distribute a binary of <b>pcre2test</b> linked in this
|
|
way, there may be licensing issues. These can be avoided by linking instead
|
|
with <b>libedit</b>, which has a BSD licence.
|
|
</P>
|
|
<P>
|
|
Setting --enable-pcre2test-libreadline causes the <b>-lreadline</b> option to be
|
|
added to the <b>pcre2test</b> build. In many operating environments with a
|
|
sytem-installed readline library this is sufficient. However, in some
|
|
environments (e.g. if an unmodified distribution version of readline is in
|
|
use), some extra configuration may be necessary. The INSTALL file for
|
|
<b>libreadline</b> says this:
|
|
<pre>
|
|
"Readline uses the termcap functions, but does not link with
|
|
the termcap or curses library itself, allowing applications
|
|
which link with readline the to choose an appropriate library."
|
|
</pre>
|
|
If your environment has not been set up so that an appropriate library is
|
|
automatically included, you may need to add something like
|
|
<pre>
|
|
LIBS="-ncurses"
|
|
</pre>
|
|
immediately before the <b>configure</b> command.
|
|
</P>
|
|
<br><a name="SEC18" href="#TOC1">INCLUDING DEBUGGING CODE</a><br>
|
|
<P>
|
|
If you add
|
|
<pre>
|
|
--enable-debug
|
|
</pre>
|
|
to the <b>configure</b> command, additional debugging code is included in the
|
|
build. This feature is intended for use by the PCRE2 maintainers.
|
|
</P>
|
|
<br><a name="SEC19" href="#TOC1">DEBUGGING WITH VALGRIND SUPPORT</a><br>
|
|
<P>
|
|
If you add
|
|
<pre>
|
|
--enable-valgrind
|
|
</pre>
|
|
to the <b>configure</b> command, PCRE2 will use valgrind annotations to mark
|
|
certain memory regions as unaddressable. This allows it to detect invalid
|
|
memory accesses, and is mostly useful for debugging PCRE2 itself.
|
|
</P>
|
|
<br><a name="SEC20" href="#TOC1">CODE COVERAGE REPORTING</a><br>
|
|
<P>
|
|
If your C compiler is gcc, you can build a version of PCRE2 that can generate a
|
|
code coverage report for its test suite. To enable this, you must install
|
|
<b>lcov</b> version 1.6 or above. Then specify
|
|
<pre>
|
|
--enable-coverage
|
|
</pre>
|
|
to the <b>configure</b> command and build PCRE2 in the usual way.
|
|
</P>
|
|
<P>
|
|
Note that using <b>ccache</b> (a caching C compiler) is incompatible with code
|
|
coverage reporting. If you have configured <b>ccache</b> to run automatically
|
|
on your system, you must set the environment variable
|
|
<pre>
|
|
CCACHE_DISABLE=1
|
|
</pre>
|
|
before running <b>make</b> to build PCRE2, so that <b>ccache</b> is not used.
|
|
</P>
|
|
<P>
|
|
When --enable-coverage is used, the following addition targets are added to the
|
|
<i>Makefile</i>:
|
|
<pre>
|
|
make coverage
|
|
</pre>
|
|
This creates a fresh coverage report for the PCRE2 test suite. It is equivalent
|
|
to running "make coverage-reset", "make coverage-baseline", "make check", and
|
|
then "make coverage-report".
|
|
<pre>
|
|
make coverage-reset
|
|
</pre>
|
|
This zeroes the coverage counters, but does nothing else.
|
|
<pre>
|
|
make coverage-baseline
|
|
</pre>
|
|
This captures baseline coverage information.
|
|
<pre>
|
|
make coverage-report
|
|
</pre>
|
|
This creates the coverage report.
|
|
<pre>
|
|
make coverage-clean-report
|
|
</pre>
|
|
This removes the generated coverage report without cleaning the coverage data
|
|
itself.
|
|
<pre>
|
|
make coverage-clean-data
|
|
</pre>
|
|
This removes the captured coverage data without removing the coverage files
|
|
created at compile time (*.gcno).
|
|
<pre>
|
|
make coverage-clean
|
|
</pre>
|
|
This cleans all coverage data including the generated coverage report. For more
|
|
information about code coverage, see the <b>gcov</b> and <b>lcov</b>
|
|
documentation.
|
|
</P>
|
|
<br><a name="SEC21" href="#TOC1">DISABLING THE Z AND T FORMATTING MODIFIERS</a><br>
|
|
<P>
|
|
The C99 standard defines formatting modifiers z and t for size_t and
|
|
ptrdiff_t values, respectively. By default, PCRE2 uses these modifiers in
|
|
environments other than Microsoft Visual Studio when __STDC_VERSION__ is
|
|
defined and has a value greater than or equal to 199901L (indicating C99).
|
|
However, there is at least one environment that claims to be C99 but does not
|
|
support these modifiers. If
|
|
<pre>
|
|
--disable-percent-zt
|
|
</pre>
|
|
is specified, no use is made of the z or t modifiers. Instead or %td or %zu,
|
|
%lu is used, with a cast for size_t values.
|
|
</P>
|
|
<br><a name="SEC22" href="#TOC1">SUPPORT FOR FUZZERS</a><br>
|
|
<P>
|
|
There is a special option for use by people who want to run fuzzing tests on
|
|
PCRE2:
|
|
<pre>
|
|
--enable-fuzz-support
|
|
</pre>
|
|
At present this applies only to the 8-bit library. If set, it causes an extra
|
|
library called libpcre2-fuzzsupport.a to be built, but not installed. This
|
|
contains a single function called LLVMFuzzerTestOneInput() whose arguments are
|
|
a pointer to a string and the length of the string. When called, this function
|
|
tries to compile the string as a pattern, and if that succeeds, to match it.
|
|
This is done both with no options and with some random options bits that are
|
|
generated from the string.
|
|
</P>
|
|
<P>
|
|
Setting --enable-fuzz-support also causes a binary called <b>pcre2fuzzcheck</b>
|
|
to be created. This is normally run under valgrind or used when PCRE2 is
|
|
compiled with address sanitizing enabled. It calls the fuzzing function and
|
|
outputs information about what it is doing. The input strings are specified by
|
|
arguments: if an argument starts with "=" the rest of it is a literal input
|
|
string. Otherwise, it is assumed to be a file name, and the contents of the
|
|
file are the test string.
|
|
</P>
|
|
<br><a name="SEC23" href="#TOC1">OBSOLETE OPTION</a><br>
|
|
<P>
|
|
In versions of PCRE2 prior to 10.30, there were two ways of handling
|
|
backtracking in the <b>pcre2_match()</b> function. The default was to use the
|
|
system stack, but if
|
|
<pre>
|
|
--disable-stack-for-recursion
|
|
</pre>
|
|
was set, memory on the heap was used. From release 10.30 onwards this has
|
|
changed (the stack is no longer used) and this option now does nothing except
|
|
give a warning.
|
|
</P>
|
|
<br><a name="SEC24" href="#TOC1">SEE ALSO</a><br>
|
|
<P>
|
|
<b>pcre2api</b>(3), <b>pcre2-config</b>(3).
|
|
</P>
|
|
<br><a name="SEC25" href="#TOC1">AUTHOR</a><br>
|
|
<P>
|
|
Philip Hazel
|
|
<br>
|
|
University Computing Service
|
|
<br>
|
|
Cambridge, England.
|
|
<br>
|
|
</P>
|
|
<br><a name="SEC26" href="#TOC1">REVISION</a><br>
|
|
<P>
|
|
Last updated: 03 March 2019
|
|
<br>
|
|
Copyright © 1997-2019 University of Cambridge.
|
|
<br>
|
|
<p>
|
|
Return to the <a href="index.html">PCRE2 index page</a>.
|
|
</p>
|