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<html><head><title>pcre2build specification</title></head><body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB"><h1>pcre2build man page</h1><p>Return to the <a href="index.html">PCRE2 index page</a>.</p><p>This page is part of the PCRE2 HTML documentation. It was generatedautomatically from the original man page. If there is any nonsense in it,please consult the man page, in case the conversion went wrong.<br><ul><li><a name="TOC1" href="#SEC1">BUILDING PCRE2</a><li><a name="TOC2" href="#SEC2">PCRE2 BUILD-TIME OPTIONS</a><li><a name="TOC3" href="#SEC3">BUILDING 8-BIT, 16-BIT AND 32-BIT LIBRARIES</a><li><a name="TOC4" href="#SEC4">BUILDING SHARED AND STATIC LIBRARIES</a><li><a name="TOC5" href="#SEC5">UNICODE AND UTF SUPPORT</a><li><a name="TOC6" href="#SEC6">DISABLING THE USE OF \C</a><li><a name="TOC7" href="#SEC7">JUST-IN-TIME COMPILER SUPPORT</a><li><a name="TOC8" href="#SEC8">NEWLINE RECOGNITION</a><li><a name="TOC9" href="#SEC9">WHAT \R MATCHES</a><li><a name="TOC10" href="#SEC10">HANDLING VERY LARGE PATTERNS</a><li><a name="TOC11" href="#SEC11">LIMITING PCRE2 RESOURCE USAGE</a><li><a name="TOC12" href="#SEC12">LIMITING VARIABLE-LENGTH LOOKBEHIND ASSERTIONS</a><li><a name="TOC13" href="#SEC13">CREATING CHARACTER TABLES AT BUILD TIME</a><li><a name="TOC14" href="#SEC14">USING EBCDIC CODE</a><li><a name="TOC15" href="#SEC15">PCRE2GREP SUPPORT FOR EXTERNAL SCRIPTS</a><li><a name="TOC16" href="#SEC16">PCRE2GREP OPTIONS FOR COMPRESSED FILE SUPPORT</a><li><a name="TOC17" href="#SEC17">PCRE2GREP BUFFER SIZE</a><li><a name="TOC18" href="#SEC18">PCRE2TEST OPTION FOR LIBREADLINE SUPPORT</a><li><a name="TOC19" href="#SEC19">INCLUDING DEBUGGING CODE</a><li><a name="TOC20" href="#SEC20">DEBUGGING WITH VALGRIND SUPPORT</a><li><a name="TOC21" href="#SEC21">CODE COVERAGE REPORTING</a><li><a name="TOC22" href="#SEC22">DISABLING THE Z AND T FORMATTING MODIFIERS</a><li><a name="TOC23" href="#SEC23">SUPPORT FOR FUZZERS</a><li><a name="TOC24" href="#SEC24">OBSOLETE OPTION</a><li><a name="TOC25" href="#SEC25">SEE ALSO</a><li><a name="TOC26" href="#SEC26">AUTHOR</a><li><a name="TOC27" href="#SEC27">REVISION</a></ul><br><a name="SEC1" href="#TOC1">BUILDING PCRE2</a><br><P>PCRE2 is distributed with a <b>configure</b> script that can be used to buildthe library in Unix-like environments using the applications known asAutotools. Also in the distribution are files to support building using<b>CMake</b> instead of <b>configure</b>. The text file<a href="README.txt"><b>README</b></a>contains general information about building with Autotools (some of which isrepeated below), and also has some comments about building on various operatingsystems. The files in the <b>vms</b> directory support building under OpenVMS.There is a lot more information about building PCRE2 without usingAutotools (including information about using <b>CMake</b> and building "byhand") in the text file called<a href="NON-AUTOTOOLS-BUILD.txt"><b>NON-AUTOTOOLS-BUILD</b>.</a>You should consult this file as well as the<a href="README.txt"><b>README</b></a>file if you are building in a non-Unix-like environment.</P><br><a name="SEC2" href="#TOC1">PCRE2 BUILD-TIME OPTIONS</a><br><P>The rest of this document describes the optional features of PCRE2 that can beselected when the library is compiled. It assumes use of the <b>configure</b>script, where the optional features are selected or deselected by providingoptions to <b>configure</b> before running the <b>make</b> command. However, thesame options can be selected in both Unix-like and non-Unix-like environmentsif you are using <b>CMake</b> instead of <b>configure</b> to build PCRE2.</P><P>If you are not using Autotools or <b>CMake</b>, option selection can be done byediting the <b>config.h</b> file, or by passing parameter settings to thecompiler, as described in<a href="NON-AUTOTOOLS-BUILD.txt"><b>NON-AUTOTOOLS-BUILD</b>.</a></P><P>The complete list of options for <b>configure</b> (which includes the standardones such as the selection of the installation directory) can be obtained byrunning<pre> ./configure --help</pre>The following sections include descriptions of "on/off" options whose namesbegin with --enable or --disable. Because of the way that <b>configure</b>works, --enable and --disable always come in pairs, so the complementary optionalways exists as well, but as it specifies the default, it is not described.Options that specify values have names that start with --with. At the end of a<b>configure</b> run, a summary of the configuration is output.</P><br><a name="SEC3" href="#TOC1">BUILDING 8-BIT, 16-BIT AND 32-BIT LIBRARIES</a><br><P>By default, a library called <b>libpcre2-8</b> is built, containing functionsthat take string arguments contained in arrays of bytes, interpreted either assingle-byte characters, or UTF-8 strings. You can also build two otherlibraries, called <b>libpcre2-16</b> and <b>libpcre2-32</b>, which processstrings that are contained in arrays of 16-bit and 32-bit code units,respectively. These can be interpreted either as single-unit characters orUTF-16/UTF-32 strings. To build these additional libraries, add one or both ofthe following to the <b>configure</b> command:<pre> --enable-pcre2-16 --enable-pcre2-32</pre>If you do not want the 8-bit library, add<pre> --disable-pcre2-8</pre>as well. At least one of the three libraries must be built. Note that the POSIXwrapper is for the 8-bit library only, and that <b>pcre2grep</b> is an 8-bitprogram. Neither of these are built if you select only the 16-bit or 32-bitlibraries.</P><br><a name="SEC4" href="#TOC1">BUILDING SHARED AND STATIC LIBRARIES</a><br><P>The Autotools PCRE2 building process uses <b>libtool</b> to build both sharedand static libraries by default. You can suppress an unwanted library by addingone of<pre> --disable-shared --disable-static</pre>to the <b>configure</b> command. Setting --disable-shared ensures that PCRE2libraries are built as static libraries. The binaries that are then created aspart of the build process (for example, <b>pcre2test</b> and <b>pcre2grep</b>)are linked statically with one or more PCRE2 libraries, but may also bedynamically linked with other libraries such as <b>libc</b>. If you want thesebinaries to be fully statically linked, you can set LDFLAGS like this:<br><br>LDFLAGS=--static ./configure --disable-shared<br><br>Note the two hyphens in --static. Of course, this works only if static versionsof all the relevant libraries are available for linking.</P><br><a name="SEC5" href="#TOC1">UNICODE AND UTF SUPPORT</a><br><P>By default, PCRE2 is built with support for Unicode and UTF character strings.To build it without Unicode support, add<pre> --disable-unicode</pre>to the <b>configure</b> command. This setting applies to all three libraries. Itis not possible to build one library with Unicode support and another withoutin the same configuration.</P><P>Of itself, Unicode support does not make PCRE2 treat strings as UTF-8, UTF-16or UTF-32. To do that, applications that use the library can set the PCRE2_UTFoption when they call <b>pcre2_compile()</b> to compile a pattern.Alternatively, patterns may be started with (*UTF) unless the application haslocked this out by setting PCRE2_NEVER_UTF.</P><P>UTF support allows the libraries to process character code points up to0x10ffff in the strings that they handle. Unicode support also gives access tothe Unicode properties of characters, using pattern escapes such as \P, \p,and \X. Only the general category properties such as <i>Lu</i> and <i>Nd</i>,script names, and some bi-directional properties are supported. Details aregiven in the<a href="pcre2pattern.html"><b>pcre2pattern</b></a>documentation.</P><P>Pattern escapes such as \d and \w do not by default make use of Unicodeproperties. The application can request that they do by setting the PCRE2_UCPoption. Unless the application has set PCRE2_NEVER_UCP, a pattern may alsorequest this by starting with (*UCP).</P><br><a name="SEC6" href="#TOC1">DISABLING THE USE OF \C</a><br><P>The \C escape sequence, which matches a single code unit, even in a UTF mode,can cause unpredictable behaviour because it may leave the current matchingpoint in the middle of a multi-code-unit character. The application can lock itout by setting the PCRE2_NEVER_BACKSLASH_C option when calling<b>pcre2_compile()</b>. There is also a build-time option<pre> --enable-never-backslash-C</pre>(note the upper case C) which locks out the use of \C entirely.</P><br><a name="SEC7" href="#TOC1">JUST-IN-TIME COMPILER SUPPORT</a><br><P>Just-in-time (JIT) compiler support is included in the build by specifying<pre> --enable-jit</pre>This support is available only for certain hardware architectures. If thisoption is set for an unsupported architecture, a building error occurs.If in doubt, use<pre> --enable-jit=auto</pre>which enables JIT only if the current hardware is supported. You can checkif JIT is enabled in the configuration summary that is output at the end of a<b>configure</b> run. If you are enabling JIT under SELinux you may also want toadd<pre> --enable-jit-sealloc</pre>which enables the use of an execmem allocator in JIT that is compatible withSELinux. This has no effect if JIT is not enabled. See the<a href="pcre2jit.html"><b>pcre2jit</b></a>documentation for a discussion of JIT usage. When JIT support is enabled,<b>pcre2grep</b> automatically makes use of it, unless you add<pre> --disable-pcre2grep-jit</pre>to the <b>configure</b> command.</P><br><a name="SEC8" href="#TOC1">NEWLINE RECOGNITION</a><br><P>By default, PCRE2 interprets the linefeed (LF) character as indicating the endof a line. This is the normal newline character on Unix-like systems. You cancompile PCRE2 to use carriage return (CR) instead, by adding<pre> --enable-newline-is-cr</pre>to the <b>configure</b> command. There is also an --enable-newline-is-lf option,which explicitly specifies linefeed as the newline character.</P><P>Alternatively, you can specify that line endings are to be indicated by thetwo-character sequence CRLF (CR immediately followed by LF). If you want this,add<pre> --enable-newline-is-crlf</pre>to the <b>configure</b> command. There is a fourth option, specified by<pre> --enable-newline-is-anycrlf</pre>which causes PCRE2 to recognize any of the three sequences CR, LF, or CRLF asindicating a line ending. A fifth option, specified by<pre> --enable-newline-is-any</pre>causes PCRE2 to recognize any Unicode newline sequence. The Unicode newlinesequences are the three just mentioned, plus the single characters VT (verticaltab, U+000B), FF (form feed, U+000C), NEL (next line, U+0085), LS (lineseparator, U+2028), and PS (paragraph separator, U+2029). The final option is<pre> --enable-newline-is-nul</pre>which causes NUL (binary zero) to be set as the default line-ending character.</P><P>Whatever default line ending convention is selected when PCRE2 is built can beoverridden by applications that use the library. At build time it isrecommended to use the standard for your operating system.</P><br><a name="SEC9" href="#TOC1">WHAT \R MATCHES</a><br><P>By default, the sequence \R in a pattern matches any Unicode newline sequence,independently of what has been selected as the line ending sequence. If youspecify<pre> --enable-bsr-anycrlf</pre>the default is changed so that \R matches only CR, LF, or CRLF. Whatever isselected when PCRE2 is built can be overridden by applications that use thelibrary.</P><br><a name="SEC10" href="#TOC1">HANDLING VERY LARGE PATTERNS</a><br><P>Within a compiled pattern, offset values are used to point from one part toanother (for example, from an opening parenthesis to an alternationmetacharacter). By default, in the 8-bit and 16-bit libraries, two-byte valuesare used for these offsets, leading to a maximum size for a compiled pattern ofaround 64 thousand code units. This is sufficient to handle all but the mostgigantic patterns. Nevertheless, some people do want to process truly enormouspatterns, so it is possible to compile PCRE2 to use three-byte or four-byteoffsets by adding a setting such as<pre> --with-link-size=3</pre>to the <b>configure</b> command. The value given must be 2, 3, or 4. For the16-bit library, a value of 3 is rounded up to 4. In these libraries, usinglonger offsets slows down the operation of PCRE2 because it has to loadadditional data when handling them. For the 32-bit library the value is always4 and cannot be overridden; the value of --with-link-size is ignored.</P><br><a name="SEC11" href="#TOC1">LIMITING PCRE2 RESOURCE USAGE</a><br><P>The <b>pcre2_match()</b> function increments a counter each time it goes roundits main loop. Putting a limit on this counter controls the amount of computingresource used by a single call to <b>pcre2_match()</b>. The limit can be changedat run time, as described in the<a href="pcre2api.html"><b>pcre2api</b></a>documentation. The default is 10 million, but this can be changed by adding asetting such as<pre> --with-match-limit=500000</pre>to the <b>configure</b> command. This setting also applies to the<b>pcre2_dfa_match()</b> matching function, and to JIT matching (though thecounting is done differently).</P><P>The <b>pcre2_match()</b> function uses heap memory to record backtrackingpoints. The more nested backtracking points there are (that is, the deeper thesearch tree), the more memory is needed. There is an upper limit, specified inkibibytes (units of 1024 bytes). This limit can be changed at run time, asdescribed in the<a href="pcre2api.html"><b>pcre2api</b></a>documentation. The default limit (in effect unlimited) is 20 million. You canchange this by a setting such as<pre> --with-heap-limit=500</pre>which limits the amount of heap to 500 KiB. This limit applies only tointerpretive matching in <b>pcre2_match()</b> and <b>pcre2_dfa_match()</b>, whichmay also use the heap for internal workspace when processing complicatedpatterns. This limit does not apply when JIT (which has its own memoryarrangements) is used.</P><P>You can also explicitly limit the depth of nested backtracking in the<b>pcre2_match()</b> interpreter. This limit defaults to the value that is setfor --with-match-limit. You can set a lower default limit by adding, forexample,<pre> --with-match-limit-depth=10000</pre>to the <b>configure</b> command. This value can be overridden at run time. Thisdepth limit indirectly limits the amount of heap memory that is used, butbecause the size of each backtracking "frame" depends on the number ofcapturing parentheses in a pattern, the amount of heap that is used before thelimit is reached varies from pattern to pattern. This limit was more useful inversions before 10.30, where function recursion was used for backtracking.</P><P>As well as applying to <b>pcre2_match()</b>, the depth limit also controlsthe depth of recursive function calls in <b>pcre2_dfa_match()</b>. These areused for lookaround assertions, atomic groups, and recursion within patterns.The limit does not apply to JIT matching.</P><br><a name="SEC12" href="#TOC1">LIMITING VARIABLE-LENGTH LOOKBEHIND ASSERTIONS</a><br><P>Lookbehind assertions in which one or more branches can match a variable numberof characters are supported only if there is a maximum matching length for eachtop-level branch. There is a limit to this maximum that defaults to 255characters. You can alter this default by a setting such as<pre> --with-max-varlookbehind=100</pre>The limit can be changed at runtime by calling<b>pcre2_set_max_varlookbehind()</b>. Lookbehind assertions in which everybranch matches a fixed number of characters (not necessarily all the same) arenot constrained by this limit.<a name="createtables"></a></P><br><a name="SEC13" href="#TOC1">CREATING CHARACTER TABLES AT BUILD TIME</a><br><P>PCRE2 uses fixed tables for processing characters whose code points are lessthan 256. By default, PCRE2 is built with a set of tables that are distributedin the file <i>src/pcre2_chartables.c.dist</i>. These tables are for ASCII codesonly. If you add<pre> --enable-rebuild-chartables</pre>to the <b>configure</b> command, the distributed tables are no longer used.Instead, a program called <b>pcre2_dftables</b> is compiled and run. Thisoutputs the source for new set of tables, created in the default locale of yourC run-time system. This method of replacing the tables does not work if you arecross compiling, because <b>pcre2_dftables</b> needs to be run on the localhost and therefore not compiled with the cross compiler.</P><P>If you need to create alternative tables when cross compiling, you will have todo so "by hand". There may also be other reasons for creating tables manually.To cause <b>pcre2_dftables</b> to be built on the local host, run a normalcompiling command, and then run the program with the output file as itsargument, for example:<pre> cc src/pcre2_dftables.c -o pcre2_dftables ./pcre2_dftables src/pcre2_chartables.c</pre>This builds the tables in the default locale of the local host. If you want tospecify a locale, you must use the -L option:<pre> LC_ALL=fr_FR ./pcre2_dftables -L src/pcre2_chartables.c</pre>You can also specify -b (with or without -L). This causes the tables to bewritten in binary instead of as source code. A set of binary tables can beloaded into memory by an application and passed to <b>pcre2_compile()</b> in thesame way as tables created by calling <b>pcre2_maketables()</b>. The tables arejust a string of bytes, independent of hardware characteristics such asendianness. This means they can be bundled with an application that runs indifferent environments, to ensure consistent behaviour.</P><br><a name="SEC14" href="#TOC1">USING EBCDIC CODE</a><br><P>PCRE2 assumes by default that it will run in an environment where the charactercode is ASCII or Unicode, which is a superset of ASCII. This is the case formost computer operating systems. PCRE2 can, however, be compiled to run in an8-bit EBCDIC environment by adding<pre> --enable-ebcdic --disable-unicode</pre>to the <b>configure</b> command. This setting implies--enable-rebuild-chartables. You should only use it if you know that you are inan EBCDIC environment (for example, an IBM mainframe operating system).</P><P>It is not possible to support both EBCDIC and UTF-8 codes in the same versionof the library. Consequently, --enable-unicode and --enable-ebcdic are mutuallyexclusive.</P><P>The EBCDIC character that corresponds to an ASCII LF is assumed to have thevalue 0x15 by default. However, in some EBCDIC environments, 0x25 is used. Insuch an environment you should use<pre> --enable-ebcdic-nl25</pre>as well as, or instead of, --enable-ebcdic. The EBCDIC character for CR has thesame value as in ASCII, namely, 0x0d. Whichever of 0x15 and 0x25 is <i>not</i>chosen as LF is made to correspond to the Unicode NEL character (which, inUnicode, is 0x85).</P><P>The options that select newline behaviour, such as --enable-newline-is-cr,and equivalent run-time options, refer to these character values in an EBCDICenvironment.</P><br><a name="SEC15" href="#TOC1">PCRE2GREP SUPPORT FOR EXTERNAL SCRIPTS</a><br><P>By default <b>pcre2grep</b> supports the use of callouts with string argumentswithin the patterns it is matching. There are two kinds: one that generatesoutput using local code, and another that calls an external program or script.If --disable-pcre2grep-callout-fork is added to the <b>configure</b> command,only the first kind of callout is supported; if --disable-pcre2grep-callout isused, all callouts are completely ignored. For more details of <b>pcre2grep</b>callouts, see the<a href="pcre2grep.html"><b>pcre2grep</b></a>documentation.</P><br><a name="SEC16" 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 sothat it recognizes files whose names end in <b>.gz</b> or <b>.bz2</b>, and readsthem 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 therelevant libraries are installed on your system. Configuration will fail ifthey are not.</P><br><a name="SEC17" href="#TOC1">PCRE2GREP BUFFER SIZE</a><br><P><b>pcre2grep</b> uses an internal buffer to hold a "window" on the file it isscanning, in order to be able to output "before" and "after" lines when itfinds a match. The default starting size of the buffer is 20KiB. The bufferitself 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 thenotional buffer size. If a longer line is encountered, <b>pcre2grep</b>automatically expands the buffer, up to a specified maximum size, whose defaultis 1MiB or the starting size, whichever is the larger. You can change thedefault 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 <b>pcre2grep</b> can overridethese values by using --buffer-size and --max-buffer-size on the command line.</P><br><a name="SEC18" 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 isfrom a terminal, it reads it using the <b>readline()</b> function. This providesline-editing and history facilities. Note that <b>libreadline</b> isGPL-licensed, so if you distribute a binary of <b>pcre2test</b> linked in thisway, there may be licensing issues. These can be avoided by linking insteadwith <b>libedit</b>, which has a BSD licence.</P><P>Setting --enable-pcre2test-libreadline causes the <b>-lreadline</b> option to beadded to the <b>pcre2test</b> build. In many operating environments with asystem-installed readline library this is sufficient. However, in someenvironments (e.g. if an unmodified distribution version of readline is inuse), 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 isautomatically included, you may need to add something like<pre> LIBS="-ncurses"</pre>immediately before the <b>configure</b> command.</P><br><a name="SEC19" 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 thebuild. This feature is intended for use by the PCRE2 maintainers.</P><br><a name="SEC20" 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 markcertain memory regions as unaddressable. This allows it to detect invalidmemory accesses, and is mostly useful for debugging PCRE2 itself.</P><br><a name="SEC21" href="#TOC1">CODE COVERAGE REPORTING</a><br><P>If your C compiler is gcc, you can build a version of PCRE2 that can generate acode 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 codecoverage reporting. If you have configured <b>ccache</b> to run automaticallyon 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 equivalentto running "make coverage-reset", "make coverage-baseline", "make check", andthen "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 dataitself.<pre> make coverage-clean-data</pre>This removes the captured coverage data without removing the coverage filescreated at compile time (*.gcno).<pre> make coverage-clean</pre>This cleans all coverage data including the generated coverage report. For moreinformation about code coverage, see the <b>gcov</b> and <b>lcov</b>documentation.</P><br><a name="SEC22" href="#TOC1">DISABLING THE Z AND T FORMATTING MODIFIERS</a><br><P>The C99 standard defines formatting modifiers z and t for size_t andptrdiff_t values, respectively. By default, PCRE2 uses these modifiers inenvironments other than old versions of Microsoft Visual Studio when__STDC_VERSION__ is defined and has a value greater than or equal to 199901L(indicating support for C99).However, there is at least one environment that claims to be C99 but does notsupport these modifiers. If<pre> --disable-percent-zt</pre>is specified, no use is made of the z or t modifiers. Instead of %td or %zu,a suitable format is used depending in the size of long for the platform.</P><br><a name="SEC23" href="#TOC1">SUPPORT FOR FUZZERS</a><br><P>There is a special option for use by people who want to run fuzzing tests onPCRE2:<pre> --enable-fuzz-support</pre>At present this applies only to the 8-bit library. If set, it causes an extralibrary called libpcre2-fuzzsupport.a to be built, but not installed. Thiscontains a single function called LLVMFuzzerTestOneInput() whose arguments area pointer to a string and the length of the string. When called, this functiontries 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 aregenerated 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 iscompiled with address sanitizing enabled. It calls the fuzzing function andoutputs information about what it is doing. The input strings are specified byarguments: if an argument starts with "=" the rest of it is a literal inputstring. Otherwise, it is assumed to be a file name, and the contents of thefile are the test string.</P><br><a name="SEC24" href="#TOC1">OBSOLETE OPTION</a><br><P>In versions of PCRE2 prior to 10.30, there were two ways of handlingbacktracking in the <b>pcre2_match()</b> function. The default was to use thesystem stack, but if<pre> --disable-stack-for-recursion</pre>was set, memory on the heap was used. From release 10.30 onwards this haschanged (the stack is no longer used) and this option now does nothing exceptgive a warning.</P><br><a name="SEC25" href="#TOC1">SEE ALSO</a><br><P><b>pcre2api</b>(3), <b>pcre2-config</b>(3).</P><br><a name="SEC26" href="#TOC1">AUTHOR</a><br><P>Philip Hazel<br>Retired from University Computing Service<br>Cambridge, England.<br></P><br><a name="SEC27" href="#TOC1">REVISION</a><br><P>Last updated: 15 April 2024<br>Copyright © 1997-2024 University of Cambridge.<br><p>Return to the <a href="index.html">PCRE2 index page</a>.</p>
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