| .TH PCRE2BUILD 3 "16 October 2015" "PCRE2 10.21" |
| .SH NAME |
| PCRE2 - Perl-compatible regular expressions (revised API) |
| . |
| . |
| .SH "BUILDING PCRE2" |
| .rs |
| .sp |
| PCRE2 is distributed with a \fBconfigure\fP script that can be used to build |
| the library in Unix-like environments using the applications known as |
| Autotools. Also in the distribution are files to support building using |
| \fBCMake\fP instead of \fBconfigure\fP. The text file |
| .\" HTML <a href="README.txt"> |
| .\" </a> |
| \fBREADME\fP |
| .\" |
| contains general information about building with Autotools (some of which is |
| repeated below), and also has some comments about building on various operating |
| systems. There is a lot more information about building PCRE2 without using |
| Autotools (including information about using \fBCMake\fP and building "by |
| hand") in the text file called |
| .\" HTML <a href="NON-AUTOTOOLS-BUILD.txt"> |
| .\" </a> |
| \fBNON-AUTOTOOLS-BUILD\fP. |
| .\" |
| You should consult this file as well as the |
| .\" HTML <a href="README.txt"> |
| .\" </a> |
| \fBREADME\fP |
| .\" |
| file if you are building in a non-Unix-like environment. |
| . |
| . |
| .SH "PCRE2 BUILD-TIME OPTIONS" |
| .rs |
| .sp |
| The rest of this document describes the optional features of PCRE2 that can be |
| selected when the library is compiled. It assumes use of the \fBconfigure\fP |
| script, where the optional features are selected or deselected by providing |
| options to \fBconfigure\fP before running the \fBmake\fP command. However, the |
| same options can be selected in both Unix-like and non-Unix-like environments |
| if you are using \fBCMake\fP instead of \fBconfigure\fP to build PCRE2. |
| .P |
| If you are not using Autotools or \fBCMake\fP, option selection can be done by |
| editing the \fBconfig.h\fP file, or by passing parameter settings to the |
| compiler, as described in |
| .\" HTML <a href="NON-AUTOTOOLS-BUILD.txt"> |
| .\" </a> |
| \fBNON-AUTOTOOLS-BUILD\fP. |
| .\" |
| .P |
| The complete list of options for \fBconfigure\fP (which includes the standard |
| ones such as the selection of the installation directory) can be obtained by |
| running |
| .sp |
| ./configure --help |
| .sp |
| The following sections include descriptions of options whose names begin with |
| --enable or --disable. These settings specify changes to the defaults for the |
| \fBconfigure\fP command. Because of the way that \fBconfigure\fP 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 "BUILDING 8-BIT, 16-BIT AND 32-BIT LIBRARIES" |
| .rs |
| .sp |
| By default, a library called \fBlibpcre2-8\fP is built, containing functions |
| that take string arguments contained in vectors of bytes, interpreted either as |
| single-byte characters, or UTF-8 strings. You can also build two other |
| libraries, called \fBlibpcre2-16\fP and \fBlibpcre2-32\fP, which process |
| strings that are contained in vectors of 16-bit and 32-bit code units, |
| respectively. These can be interpreted either as single-unit characters or |
| UTF-16/UTF-32 strings. To build these additional libraries, add one or both of |
| the following to the \fBconfigure\fP command: |
| .sp |
| --enable-pcre2-16 |
| --enable-pcre2-32 |
| .sp |
| If you do not want the 8-bit library, add |
| .sp |
| --disable-pcre2-8 |
| .sp |
| as well. At least one of the three libraries must be built. Note that the POSIX |
| wrapper is for the 8-bit library only, and that \fBpcre2grep\fP is an 8-bit |
| program. Neither of these are built if you select only the 16-bit or 32-bit |
| libraries. |
| . |
| . |
| .SH "BUILDING SHARED AND STATIC LIBRARIES" |
| .rs |
| .sp |
| The Autotools PCRE2 building process uses \fBlibtool\fP to build both shared |
| and static libraries by default. You can suppress an unwanted library by adding |
| one of |
| .sp |
| --disable-shared |
| --disable-static |
| .sp |
| to the \fBconfigure\fP command. |
| . |
| . |
| .SH "UNICODE AND UTF SUPPORT" |
| .rs |
| .sp |
| By default, PCRE2 is built with support for Unicode and UTF character strings. |
| To build it without Unicode support, add |
| .sp |
| --disable-unicode |
| .sp |
| to the \fBconfigure\fP command. This setting applies to all three libraries. It |
| is not possible to build one library with Unicode support, and another without, |
| in the same configuration. |
| .P |
| Of itself, Unicode support does not make PCRE2 treat strings as UTF-8, UTF-16 |
| or UTF-32. To do that, applications that use the library can set the PCRE2_UTF |
| option when they call \fBpcre2_compile()\fP to compile a pattern. |
| Alternatively, patterns may be started with (*UTF) unless the application has |
| locked this out by setting PCRE2_NEVER_UTF. |
| .P |
| UTF support allows the libraries to process character code points up to |
| 0x10ffff in the strings that they handle. It also provides support for |
| accessing the Unicode properties of such characters, using pattern escapes such |
| as \eP, \ep, and \eX. Only the general category properties such as \fILu\fP and |
| \fINd\fP are supported. Details are given in the |
| .\" HREF |
| \fBpcre2pattern\fP |
| .\" |
| documentation. |
| .P |
| Pattern escapes such as \ed and \ew do not by default make use of Unicode |
| properties. The application can request that they do by setting the PCRE2_UCP |
| option. Unless the application has set PCRE2_NEVER_UCP, a pattern may also |
| request this by starting with (*UCP). |
| . |
| . |
| .SH "DISABLING THE USE OF \eC" |
| .rs |
| .sp |
| The \eC escape sequence, which matches a single code unit, even in a UTF mode, |
| can cause unpredictable behaviour because it may leave the current matching |
| point in the middle of a multi-code-unit character. The application can lock it |
| out by setting the PCRE2_NEVER_BACKSLASH_C option when calling |
| \fBpcre2_compile()\fP. There is also a build-time option |
| .sp |
| --enable-never-backslash-C |
| .sp |
| (note the upper case C) which locks out the use of \eC entirely. |
| . |
| . |
| .SH "JUST-IN-TIME COMPILER SUPPORT" |
| .rs |
| .sp |
| Just-in-time compiler support is included in the build by specifying |
| .sp |
| --enable-jit |
| .sp |
| This support is available only for certain hardware architectures. If this |
| option is set for an unsupported architecture, a building error occurs. |
| See the |
| .\" HREF |
| \fBpcre2jit\fP |
| .\" |
| documentation for a discussion of JIT usage. When JIT support is enabled, |
| pcre2grep automatically makes use of it, unless you add |
| .sp |
| --disable-pcre2grep-jit |
| .sp |
| to the "configure" command. |
| . |
| . |
| .SH "NEWLINE RECOGNITION" |
| .rs |
| .sp |
| By default, PCRE2 interprets the linefeed (LF) character as indicating the end |
| of a line. This is the normal newline character on Unix-like systems. You can |
| compile PCRE2 to use carriage return (CR) instead, by adding |
| .sp |
| --enable-newline-is-cr |
| .sp |
| to the \fBconfigure\fP command. There is also an --enable-newline-is-lf option, |
| which explicitly specifies linefeed as the newline character. |
| .P |
| Alternatively, you can specify that line endings are to be indicated by the |
| two-character sequence CRLF (CR immediately followed by LF). If you want this, |
| add |
| .sp |
| --enable-newline-is-crlf |
| .sp |
| to the \fBconfigure\fP command. There is a fourth option, specified by |
| .sp |
| --enable-newline-is-anycrlf |
| .sp |
| which causes PCRE2 to recognize any of the three sequences CR, LF, or CRLF as |
| indicating a line ending. Finally, a fifth option, specified by |
| .sp |
| --enable-newline-is-any |
| .sp |
| causes PCRE2 to recognize any Unicode newline sequence. The Unicode newline |
| sequences are the three just mentioned, plus the single characters VT (vertical |
| tab, U+000B), FF (form feed, U+000C), NEL (next line, U+0085), LS (line |
| separator, U+2028), and PS (paragraph separator, U+2029). |
| .P |
| Whatever default line ending convention is selected when PCRE2 is built can be |
| overridden by applications that use the library. At build time it is |
| conventional to use the standard for your operating system. |
| . |
| . |
| .SH "WHAT \eR MATCHES" |
| .rs |
| .sp |
| By default, the sequence \eR in a pattern matches any Unicode newline sequence, |
| independently of what has been selected as the line ending sequence. If you |
| specify |
| .sp |
| --enable-bsr-anycrlf |
| .sp |
| the default is changed so that \eR matches only CR, LF, or CRLF. Whatever is |
| selected when PCRE2 is built can be overridden by applications that use the |
| called. |
| . |
| . |
| .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, in the 8-bit and 16-bit libraries, two-byte values |
| are used for these offsets, leading to a maximum size for a compiled pattern of |
| around 64K code units. This is sufficient to handle all but the most gigantic |
| patterns. Nevertheless, some people do want to process truly enormous patterns, |
| so it is possible to compile PCRE2 to use three-byte or four-byte offsets by |
| adding a setting such as |
| .sp |
| --with-link-size=3 |
| .sp |
| to the \fBconfigure\fP command. The value given must be 2, 3, or 4. For the |
| 16-bit library, a value of 3 is rounded up to 4. In these libraries, using |
| longer offsets slows down the operation of PCRE2 because it has to load |
| additional data when handling them. For the 32-bit library the value is always |
| 4 and cannot be overridden; the value of --with-link-size is ignored. |
| . |
| . |
| .SH "AVOIDING EXCESSIVE STACK USAGE" |
| .rs |
| .sp |
| When matching with the \fBpcre2_match()\fP function, PCRE2 implements |
| backtracking by making recursive calls to an internal function called |
| \fBmatch()\fP. In environments where the size of the stack is limited, this can |
| severely limit PCRE2's operation. (The Unix environment does not usually suffer |
| from this problem, but it may sometimes be necessary to increase the maximum |
| stack size. There is a discussion in the |
| .\" HREF |
| \fBpcre2stack\fP |
| .\" |
| documentation.) An alternative approach to recursion that uses memory from the |
| heap to remember data, instead of using recursive function calls, has been |
| implemented to work round the problem of limited stack size. If you want to |
| build a version of PCRE2 that works this way, add |
| .sp |
| --disable-stack-for-recursion |
| .sp |
| to the \fBconfigure\fP command. By default, the system functions \fBmalloc()\fP |
| and \fBfree()\fP are called to manage the heap memory that is required, but |
| custom memory management functions can be called instead. PCRE2 runs noticeably |
| more slowly when built in this way. This option affects only the |
| \fBpcre2_match()\fP function; it is not relevant for \fBpcre2_dfa_match()\fP. |
| . |
| . |
| .SH "LIMITING PCRE2 RESOURCE USAGE" |
| .rs |
| .sp |
| Internally, PCRE2 has a function called \fBmatch()\fP, which it calls |
| repeatedly (sometimes recursively) when matching a pattern with the |
| \fBpcre2_match()\fP function. By controlling the maximum number of times this |
| function may be called during a single matching operation, a limit can be |
| placed on the resources used by a single call to \fBpcre2_match()\fP. The limit |
| can be changed at run time, as described in the |
| .\" HREF |
| \fBpcre2api\fP |
| .\" |
| documentation. The default is 10 million, but this can be changed by adding a |
| setting such as |
| .sp |
| --with-match-limit=500000 |
| .sp |
| to the \fBconfigure\fP command. This setting has no effect on the |
| \fBpcre2_dfa_match()\fP matching function. |
| .P |
| In some environments it is desirable to limit the depth of recursive calls of |
| \fBmatch()\fP more strictly than the total number of calls, in order to |
| restrict the maximum amount of stack (or heap, if --disable-stack-for-recursion |
| is specified) that is used. A second limit controls this; it defaults to the |
| value that is set for --with-match-limit, which imposes no additional |
| constraints. However, you can set a lower limit by adding, for example, |
| .sp |
| --with-match-limit-recursion=10000 |
| .sp |
| to the \fBconfigure\fP command. This value can also be overridden at run time. |
| . |
| . |
| .SH "CREATING CHARACTER TABLES AT BUILD TIME" |
| .rs |
| .sp |
| PCRE2 uses fixed tables for processing characters whose code points are less |
| than 256. By default, PCRE2 is built with a set of tables that are distributed |
| in the file \fIsrc/pcre2_chartables.c.dist\fP. These tables are for ASCII codes |
| only. If you add |
| .sp |
| --enable-rebuild-chartables |
| .sp |
| to the \fBconfigure\fP command, the distributed tables are no longer used. |
| Instead, a program called \fBdftables\fP is compiled and run. This outputs the |
| source for new set of tables, created in the default locale of your C run-time |
| system. (This method of replacing the tables does not work if you are cross |
| compiling, because \fBdftables\fP is run on the local host. If you need to |
| create alternative tables when cross compiling, you will have to do so "by |
| hand".) |
| . |
| . |
| .SH "USING EBCDIC CODE" |
| .rs |
| .sp |
| PCRE2 assumes by default that it will run in an environment where the character |
| code is ASCII or Unicode, which is a superset of ASCII. This is the case for |
| most computer operating systems. PCRE2 can, however, be compiled to run in an |
| 8-bit EBCDIC environment by adding |
| .sp |
| --enable-ebcdic --disable-unicode |
| .sp |
| to the \fBconfigure\fP command. This setting implies |
| --enable-rebuild-chartables. You should only use it if you know that you are in |
| an EBCDIC environment (for example, an IBM mainframe operating system). |
| .P |
| It is not possible to support both EBCDIC and UTF-8 codes in the same version |
| of the library. Consequently, --enable-unicode and --enable-ebcdic are mutually |
| exclusive. |
| .P |
| The EBCDIC character that corresponds to an ASCII LF is assumed to have the |
| value 0x15 by default. However, in some EBCDIC environments, 0x25 is used. In |
| such an environment you should use |
| .sp |
| --enable-ebcdic-nl25 |
| .sp |
| as well as, or instead of, --enable-ebcdic. The EBCDIC character for CR has the |
| same value as in ASCII, namely, 0x0d. Whichever of 0x15 and 0x25 is \fInot\fP |
| chosen as LF is made to correspond to the Unicode NEL character (which, in |
| Unicode, is 0x85). |
| .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 EBCDIC |
| environment. |
| . |
| . |
| .SH "PCRE2GREP OPTIONS FOR COMPRESSED FILE SUPPORT" |
| .rs |
| .sp |
| By default, \fBpcre2grep\fP reads all files as plain text. You can build it so |
| that it recognizes files whose names end in \fB.gz\fP or \fB.bz2\fP, and reads |
| them with \fBlibz\fP or \fBlibbz2\fP, respectively, by adding one or both of |
| .sp |
| --enable-pcre2grep-libz |
| --enable-pcre2grep-libbz2 |
| .sp |
| to the \fBconfigure\fP command. These options naturally require that the |
| relevant libraries are installed on your system. Configuration will fail if |
| they are not. |
| . |
| . |
| .SH "PCRE2GREP BUFFER SIZE" |
| .rs |
| .sp |
| \fBpcre2grep\fP 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 size of the buffer is controlled by a parameter whose |
| default value is 20K. 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 parameter size. You can change the default |
| parameter value by adding, for example, |
| .sp |
| --with-pcre2grep-bufsize=50K |
| .sp |
| to the \fBconfigure\fP command. The caller of \fPpcre2grep\fP can override this |
| value by using --buffer-size on the command line.. |
| . |
| . |
| .SH "PCRE2TEST OPTION FOR LIBREADLINE SUPPORT" |
| .rs |
| .sp |
| If you add one of |
| .sp |
| --enable-pcre2test-libreadline |
| --enable-pcre2test-libedit |
| .sp |
| to the \fBconfigure\fP command, \fBpcre2test\fP is linked with the |
| \fBlibreadline\fP or\fBlibedit\fP library, respectively, and when its input is |
| from a terminal, it reads it using the \fBreadline()\fP function. This provides |
| line-editing and history facilities. Note that \fBlibreadline\fP is |
| GPL-licensed, so if you distribute a binary of \fBpcre2test\fP linked in this |
| way, there may be licensing issues. These can be avoided by linking instead |
| with \fBlibedit\fP, which has a BSD licence. |
| .P |
| Setting --enable-pcre2test-libreadline causes the \fB-lreadline\fP option to be |
| added to the \fBpcre2test\fP 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 |
| \fBlibreadline\fP says this: |
| .sp |
| "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." |
| .sp |
| If your environment has not been set up so that an appropriate library is |
| automatically included, you may need to add something like |
| .sp |
| LIBS="-ncurses" |
| .sp |
| immediately before the \fBconfigure\fP command. |
| . |
| . |
| .SH "INCLUDING DEBUGGING CODE" |
| .rs |
| .sp |
| If you add |
| .sp |
| --enable-debug |
| .sp |
| to the \fBconfigure\fP command, additional debugging code is included in the |
| build. This feature is intended for use by the PCRE2 maintainers. |
| . |
| . |
| .SH "DEBUGGING WITH VALGRIND SUPPORT" |
| .rs |
| .sp |
| If you add |
| .sp |
| --enable-valgrind |
| .sp |
| to the \fBconfigure\fP 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. |
| . |
| . |
| .SH "CODE COVERAGE REPORTING" |
| .rs |
| .sp |
| 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 |
| \fBlcov\fP version 1.6 or above. Then specify |
| .sp |
| --enable-coverage |
| .sp |
| to the \fBconfigure\fP command and build PCRE2 in the usual way. |
| .P |
| Note that using \fBccache\fP (a caching C compiler) is incompatible with code |
| coverage reporting. If you have configured \fBccache\fP to run automatically |
| on your system, you must set the environment variable |
| .sp |
| CCACHE_DISABLE=1 |
| .sp |
| before running \fBmake\fP to build PCRE2, so that \fBccache\fP is not used. |
| .P |
| When --enable-coverage is used, the following addition targets are added to the |
| \fIMakefile\fP: |
| .sp |
| make coverage |
| .sp |
| 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". |
| .sp |
| make coverage-reset |
| .sp |
| This zeroes the coverage counters, but does nothing else. |
| .sp |
| make coverage-baseline |
| .sp |
| This captures baseline coverage information. |
| .sp |
| make coverage-report |
| .sp |
| This creates the coverage report. |
| .sp |
| make coverage-clean-report |
| .sp |
| This removes the generated coverage report without cleaning the coverage data |
| itself. |
| .sp |
| make coverage-clean-data |
| .sp |
| This removes the captured coverage data without removing the coverage files |
| created at compile time (*.gcno). |
| .sp |
| make coverage-clean |
| .sp |
| This cleans all coverage data including the generated coverage report. For more |
| information about code coverage, see the \fBgcov\fP and \fBlcov\fP |
| documentation. |
| . |
| . |
| .SH "SEE ALSO" |
| .rs |
| .sp |
| \fBpcre2api\fP(3), \fBpcre2-config\fP(3). |
| . |
| . |
| .SH AUTHOR |
| .rs |
| .sp |
| .nf |
| Philip Hazel |
| University Computing Service |
| Cambridge, England. |
| .fi |
| . |
| . |
| .SH REVISION |
| .rs |
| .sp |
| .nf |
| Last updated: 16 October 2015 |
| Copyright (c) 1997-2015 University of Cambridge. |
| .fi |