1PCRE2BUILD(3) Library Functions Manual PCRE2BUILD(3)
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6 PCRE2 - Perl-compatible regular expressions (revised API)
7
9 PCRE2 is distributed with a configure script that can be used to build
11 the library in Unix-like environments using the applications known as
12 Autotools. Also in the distribution are files to support building using
13 CMake instead of configure. The text file README contains general in‐
14 formation about building with Autotools (some of which is repeated be‐
15 low), and also has some comments about building on various operating
16 systems. There is a lot more information about building PCRE2 without
17 using Autotools (including information about using CMake and building
18 "by hand") in the text file called NON-AUTOTOOLS-BUILD. You should
19 consult this file as well as the README file if you are building in a
20 non-Unix-like environment.
21
23 The rest of this document describes the optional features of PCRE2 that
25 can be selected when the library is compiled. It assumes use of the
26 configure script, where the optional features are selected or dese‐
27 lected by providing options to configure before running the make com‐
28 mand. However, the same options can be selected in both Unix-like and
29 non-Unix-like environments if you are using CMake instead of configure
30 to build PCRE2.
31 If you are not using Autotools or CMake, option selection can be done
33 by editing the config.h file, or by passing parameter settings to the
34 compiler, as described in NON-AUTOTOOLS-BUILD.
35 The complete list of options for configure (which includes the standard
37 ones such as the selection of the installation directory) can be ob‐
38 tained by running
39 ./configure --help
41 The following sections include descriptions of "on/off" options whose
43 names begin with --enable or --disable. Because of the way that config‐
44 ure works, --enable and --disable always come in pairs, so the comple‐
45 mentary option always exists as well, but as it specifies the default,
46 it is not described. Options that specify values have names that start
47 with --with. At the end of a configure run, a summary of the configura‐
48 tion is output.
49
51 By default, a library called libpcre2-8 is built, containing functions
53 that take string arguments contained in arrays of bytes, interpreted
54 either as single-byte characters, or UTF-8 strings. You can also build
55 two other libraries, called libpcre2-16 and libpcre2-32, which process
56 strings that are contained in arrays of 16-bit and 32-bit code units,
57 respectively. These can be interpreted either as single-unit characters
58 or UTF-16/UTF-32 strings. To build these additional libraries, add one
59 or both of the following to the configure command:
60 --enable-pcre2-16
62 --enable-pcre2-32
63 If you do not want the 8-bit library, add
65 --disable-pcre2-8
67 as well. At least one of the three libraries must be built. Note that
69 the POSIX wrapper is for the 8-bit library only, and that pcre2grep is
70 an 8-bit program. Neither of these are built if you select only the
71 16-bit or 32-bit libraries.
72
74 The Autotools PCRE2 building process uses libtool to build both shared
76 and static libraries by default. You can suppress an unwanted library
77 by adding one of
78 --disable-shared
80 --disable-static
81 to the configure command.
83
85 By default, PCRE2 is built with support for Unicode and UTF character
87 strings. To build it without Unicode support, add
88 --disable-unicode
90 to the configure command. This setting applies to all three libraries.
92 It is not possible to build one library with Unicode support and an‐
93 other without in the same configuration.
94 Of itself, Unicode support does not make PCRE2 treat strings as UTF-8,
96 UTF-16 or UTF-32. To do that, applications that use the library can set
97 the PCRE2_UTF option when they call pcre2_compile() to compile a pat‐
98 tern. Alternatively, patterns may be started with (*UTF) unless the
99 application has locked this out by setting PCRE2_NEVER_UTF.
100 UTF support allows the libraries to process character code points up to
102 0x10ffff in the strings that they handle. Unicode support also gives
103 access to the Unicode properties of characters, using pattern escapes
104 such as \P, \p, and \X. Only the general category properties such as Lu
105 and Nd, script names, and some bi-directional properties are supported.
106 Details are given in the pcre2pattern documentation.
107 Pattern escapes such as \d and \w do not by default make use of Unicode
109 properties. The application can request that they do by setting the
110 PCRE2_UCP option. Unless the application has set PCRE2_NEVER_UCP, a
111 pattern may also request this by starting with (*UCP).
112
114 The \C escape sequence, which matches a single code unit, even in a UTF
116 mode, can cause unpredictable behaviour because it may leave the cur‐
117 rent matching point in the middle of a multi-code-unit character. The
118 application can lock it out by setting the PCRE2_NEVER_BACKSLASH_C op‐
119 tion when calling pcre2_compile(). There is also a build-time option
120 --enable-never-backslash-C
122 (note the upper case C) which locks out the use of \C entirely.
124
126 Just-in-time (JIT) compiler support is included in the build by speci‐
128 fying
129 --enable-jit
131 This support is available only for certain hardware architectures. If
133 this option is set for an unsupported architecture, a building error
134 occurs. If in doubt, use
135 --enable-jit=auto
137 which enables JIT only if the current hardware is supported. You can
139 check if JIT is enabled in the configuration summary that is output at
140 the end of a configure run. If you are enabling JIT under SELinux you
141 may also want to add
142 --enable-jit-sealloc
144 which enables the use of an execmem allocator in JIT that is compatible
146 with SELinux. This has no effect if JIT is not enabled. See the
147 pcre2jit documentation for a discussion of JIT usage. When JIT support
148 is enabled, pcre2grep automatically makes use of it, unless you add
149 --disable-pcre2grep-jit
151 to the configure command.
153
155 By default, PCRE2 interprets the linefeed (LF) character as indicating
157 the end of a line. This is the normal newline character on Unix-like
158 systems. You can compile PCRE2 to use carriage return (CR) instead, by
159 adding
160 --enable-newline-is-cr
162 to the configure command. There is also an --enable-newline-is-lf op‐
164 tion, which explicitly specifies linefeed as the newline character.
165 Alternatively, you can specify that line endings are to be indicated by
167 the two-character sequence CRLF (CR immediately followed by LF). If you
168 want this, add
169 --enable-newline-is-crlf
171 to the configure command. There is a fourth option, specified by
173 --enable-newline-is-anycrlf
175 which causes PCRE2 to recognize any of the three sequences CR, LF, or
177 CRLF as indicating a line ending. A fifth option, specified by
178 --enable-newline-is-any
180 causes PCRE2 to recognize any Unicode newline sequence. The Unicode
182 newline sequences are the three just mentioned, plus the single charac‐
183 ters VT (vertical tab, U+000B), FF (form feed, U+000C), NEL (next line,
184 U+0085), LS (line separator, U+2028), and PS (paragraph separator,
185 U+2029). The final option is
186 --enable-newline-is-nul
188 which causes NUL (binary zero) to be set as the default line-ending
190 character.
191 Whatever default line ending convention is selected when PCRE2 is built
193 can be overridden by applications that use the library. At build time
194 it is recommended to use the standard for your operating system.
195
197 By default, the sequence \R in a pattern matches any Unicode newline
199 sequence, independently of what has been selected as the line ending
200 sequence. If you specify
201 --enable-bsr-anycrlf
203 the default is changed so that \R matches only CR, LF, or CRLF. What‐
205 ever is selected when PCRE2 is built can be overridden by applications
206 that use the library.
207
209 Within a compiled pattern, offset values are used to point from one
211 part to another (for example, from an opening parenthesis to an alter‐
212 nation metacharacter). By default, in the 8-bit and 16-bit libraries,
213 two-byte values are used for these offsets, leading to a maximum size
214 for a compiled pattern of around 64 thousand code units. This is suffi‐
215 cient to handle all but the most gigantic patterns. Nevertheless, some
216 people do want to process truly enormous patterns, so it is possible to
217 compile PCRE2 to use three-byte or four-byte offsets by adding a set‐
218 ting such as
219 --with-link-size=3
221 to the configure command. The value given must be 2, 3, or 4. For the
223 16-bit library, a value of 3 is rounded up to 4. In these libraries,
224 using longer offsets slows down the operation of PCRE2 because it has
225 to load additional data when handling them. For the 32-bit library the
226 value is always 4 and cannot be overridden; the value of --with-link-
227 size is ignored.
228
230 The pcre2_match() function increments a counter each time it goes round
232 its main loop. Putting a limit on this counter controls the amount of
233 computing resource used by a single call to pcre2_match(). The limit
234 can be changed at run time, as described in the pcre2api documentation.
235 The default is 10 million, but this can be changed by adding a setting
236 such as
237 --with-match-limit=500000
239 to the configure command. This setting also applies to the
241 pcre2_dfa_match() matching function, and to JIT matching (though the
242 counting is done differently).
243 The pcre2_match() function uses heap memory to record backtracking
245 points. The more nested backtracking points there are (that is, the
246 deeper the search tree), the more memory is needed. There is an upper
247 limit, specified in kibibytes (units of 1024 bytes). This limit can be
248 changed at run time, as described in the pcre2api documentation. The
249 default limit (in effect unlimited) is 20 million. You can change this
250 by a setting such as
251 --with-heap-limit=500
253 which limits the amount of heap to 500 KiB. This limit applies only to
255 interpretive matching in pcre2_match() and pcre2_dfa_match(), which may
256 also use the heap for internal workspace when processing complicated
257 patterns. This limit does not apply when JIT (which has its own memory
258 arrangements) is used.
259 You can also explicitly limit the depth of nested backtracking in the
261 pcre2_match() interpreter. This limit defaults to the value that is set
262 for --with-match-limit. You can set a lower default limit by adding,
263 for example,
264 --with-match-limit-depth=10000
266 to the configure command. This value can be overridden at run time.
268 This depth limit indirectly limits the amount of heap memory that is
269 used, but because the size of each backtracking "frame" depends on the
270 number of capturing parentheses in a pattern, the amount of heap that
271 is used before the limit is reached varies from pattern to pattern.
272 This limit was more useful in versions before 10.30, where function re‐
273 cursion was used for backtracking.
274 As well as applying to pcre2_match(), the depth limit also controls the
276 depth of recursive function calls in pcre2_dfa_match(). These are used
277 for lookaround assertions, atomic groups, and recursion within pat‐
278 terns. The limit does not apply to JIT matching.
279
281 PCRE2 uses fixed tables for processing characters whose code points are
283 less than 256. By default, PCRE2 is built with a set of tables that are
284 distributed in the file src/pcre2_chartables.c.dist. These tables are
285 for ASCII codes only. If you add
286 --enable-rebuild-chartables
288 to the configure command, the distributed tables are no longer used.
290 Instead, a program called pcre2_dftables is compiled and run. This out‐
291 puts the source for new set of tables, created in the default locale of
292 your C run-time system. This method of replacing the tables does not
293 work if you are cross compiling, because pcre2_dftables needs to be run
294 on the local host and therefore not compiled with the cross compiler.
295 If you need to create alternative tables when cross compiling, you will
297 have to do so "by hand". There may also be other reasons for creating
298 tables manually. To cause pcre2_dftables to be built on the local
299 host, run a normal compiling command, and then run the program with the
300 output file as its argument, for example:
301 cc src/pcre2_dftables.c -o pcre2_dftables
303 ./pcre2_dftables src/pcre2_chartables.c
304 This builds the tables in the default locale of the local host. If you
306 want to specify a locale, you must use the -L option:
307 LC_ALL=fr_FR ./pcre2_dftables -L src/pcre2_chartables.c
309 You can also specify -b (with or without -L). This causes the tables to
311 be written in binary instead of as source code. A set of binary tables
312 can be loaded into memory by an application and passed to pcre2_com‐
313 pile() in the same way as tables created by calling pcre2_maketables().
314 The tables are just a string of bytes, independent of hardware charac‐
315 teristics such as endianness. This means they can be bundled with an
316 application that runs in different environments, to ensure consistent
317 behaviour.
318
320 PCRE2 assumes by default that it will run in an environment where the
322 character code is ASCII or Unicode, which is a superset of ASCII. This
323 is the case for most computer operating systems. PCRE2 can, however, be
324 compiled to run in an 8-bit EBCDIC environment by adding
325 --enable-ebcdic --disable-unicode
327 to the configure command. This setting implies --enable-rebuild-charta‐
329 bles. You should only use it if you know that you are in an EBCDIC en‐
330 vironment (for example, an IBM mainframe operating system).
331 It is not possible to support both EBCDIC and UTF-8 codes in the same
333 version of the library. Consequently, --enable-unicode and --enable-
334 ebcdic are mutually exclusive.
335 The EBCDIC character that corresponds to an ASCII LF is assumed to have
337 the value 0x15 by default. However, in some EBCDIC environments, 0x25
338 is used. In such an environment you should use
339 --enable-ebcdic-nl25
341 as well as, or instead of, --enable-ebcdic. The EBCDIC character for CR
343 has the same value as in ASCII, namely, 0x0d. Whichever of 0x15 and
344 0x25 is not chosen as LF is made to correspond to the Unicode NEL char‐
345 acter (which, in Unicode, is 0x85).
346 The options that select newline behaviour, such as --enable-newline-is-
348 cr, and equivalent run-time options, refer to these character values in
349 an EBCDIC environment.
350
352 By default pcre2grep supports the use of callouts with string arguments
354 within the patterns it is matching. There are two kinds: one that gen‐
355 erates output using local code, and another that calls an external pro‐
356 gram or script. If --disable-pcre2grep-callout-fork is added to the
357 configure command, only the first kind of callout is supported; if
358 --disable-pcre2grep-callout is used, all callouts are completely ig‐
359 nored. For more details of pcre2grep callouts, see the pcre2grep docu‐
360 mentation.
361
363 By default, pcre2grep reads all files as plain text. You can build it
365 so that it recognizes files whose names end in .gz or .bz2, and reads
366 them with libz or libbz2, respectively, by adding one or both of
367 --enable-pcre2grep-libz
369 --enable-pcre2grep-libbz2
370 to the configure command. These options naturally require that the rel‐
372 evant libraries are installed on your system. Configuration will fail
373 if they are not.
374
376 pcre2grep uses an internal buffer to hold a "window" on the file it is
378 scanning, in order to be able to output "before" and "after" lines when
379 it finds a match. The default starting size of the buffer is 20KiB. The
380 buffer itself is three times this size, but because of the way it is
381 used for holding "before" lines, the longest line that is guaranteed to
382 be processable is the notional buffer size. If a longer line is encoun‐
383 tered, pcre2grep automatically expands the buffer, up to a specified
384 maximum size, whose default is 1MiB or the starting size, whichever is
385 the larger. You can change the default parameter values by adding, for
386 example,
387 --with-pcre2grep-bufsize=51200
389 --with-pcre2grep-max-bufsize=2097152
390 to the configure command. The caller of pcre2grep can override these
392 values by using --buffer-size and --max-buffer-size on the command
393 line.
394
396 If you add one of
398 --enable-pcre2test-libreadline
400 --enable-pcre2test-libedit
401 to the configure command, pcre2test is linked with the libreadline or‐
403 libedit library, respectively, and when its input is from a terminal,
404 it reads it using the readline() function. This provides line-editing
405 and history facilities. Note that libreadline is GPL-licensed, so if
406 you distribute a binary of pcre2test linked in this way, there may be
407 licensing issues. These can be avoided by linking instead with libedit,
408 which has a BSD licence.
409 Setting --enable-pcre2test-libreadline causes the -lreadline option to
411 be added to the pcre2test build. In many operating environments with a
412 sytem-installed readline library this is sufficient. However, in some
413 environments (e.g. if an unmodified distribution version of readline is
414 in use), some extra configuration may be necessary. The INSTALL file
415 for libreadline says this:
416 "Readline uses the termcap functions, but does not link with
418 the termcap or curses library itself, allowing applications
419 which link with readline the to choose an appropriate library."
420 If your environment has not been set up so that an appropriate library
422 is automatically included, you may need to add something like
423 LIBS="-ncurses"
425 immediately before the configure command.
427
429 If you add
431 --enable-debug
433 to the configure command, additional debugging code is included in the
435 build. This feature is intended for use by the PCRE2 maintainers.
436
438 If you add
440 --enable-valgrind
442 to the configure command, PCRE2 will use valgrind annotations to mark
444 certain memory regions as unaddressable. This allows it to detect in‐
445 valid memory accesses, and is mostly useful for debugging PCRE2 itself.
446
448 If your C compiler is gcc, you can build a version of PCRE2 that can
450 generate a code coverage report for its test suite. To enable this, you
451 must install lcov version 1.6 or above. Then specify
452 --enable-coverage
454 to the configure command and build PCRE2 in the usual way.
456 Note that using ccache (a caching C compiler) is incompatible with code
458 coverage reporting. If you have configured ccache to run automatically
459 on your system, you must set the environment variable
460 CCACHE_DISABLE=1
462 before running make to build PCRE2, so that ccache is not used.
464 When --enable-coverage is used, the following addition targets are
466 added to the Makefile:
467 make coverage
469 This creates a fresh coverage report for the PCRE2 test suite. It is
471 equivalent to running "make coverage-reset", "make coverage-baseline",
472 "make check", and then "make coverage-report".
473 make coverage-reset
475 This zeroes the coverage counters, but does nothing else.
477 make coverage-baseline
479 This captures baseline coverage information.
481 make coverage-report
483 This creates the coverage report.
485 make coverage-clean-report
487 This removes the generated coverage report without cleaning the cover‐
489 age data itself.
490 make coverage-clean-data
492 This removes the captured coverage data without removing the coverage
494 files created at compile time (*.gcno).
495 make coverage-clean
497 This cleans all coverage data including the generated coverage report.
499 For more information about code coverage, see the gcov and lcov docu‐
500 mentation.
501
503 The C99 standard defines formatting modifiers z and t for size_t and
505 ptrdiff_t values, respectively. By default, PCRE2 uses these modifiers
506 in environments other than old versions of Microsoft Visual Studio when
507 __STDC_VERSION__ is defined and has a value greater than or equal to
508 199901L (indicating support for C99). However, there is at least one
509 environment that claims to be C99 but does not support these modifiers.
510 If
511 --disable-percent-zt
513 is specified, no use is made of the z or t modifiers. Instead of %td or
515 %zu, a suitable format is used depending in the size of long for the
516 platform.
517
519 There is a special option for use by people who want to run fuzzing
521 tests on PCRE2:
522 --enable-fuzz-support
524 At present this applies only to the 8-bit library. If set, it causes an
526 extra library called libpcre2-fuzzsupport.a to be built, but not in‐
527 stalled. This contains a single function called LLVMFuzzerTestOneIn‐
528 put() whose arguments are a pointer to a string and the length of the
529 string. When called, this function tries to compile the string as a
530 pattern, and if that succeeds, to match it. This is done both with no
531 options and with some random options bits that are generated from the
532 string.
533 Setting --enable-fuzz-support also causes a binary called pcre2fuz‐
535 zcheck to be created. This is normally run under valgrind or used when
536 PCRE2 is compiled with address sanitizing enabled. It calls the fuzzing
537 function and outputs information about what it is doing. The input
538 strings are specified by arguments: if an argument starts with "=" the
539 rest of it is a literal input string. Otherwise, it is assumed to be a
540 file name, and the contents of the file are the test string.
541
543 In versions of PCRE2 prior to 10.30, there were two ways of handling
545 backtracking in the pcre2_match() function. The default was to use the
546 system stack, but if
547 --disable-stack-for-recursion
549 was set, memory on the heap was used. From release 10.30 onwards this
551 has changed (the stack is no longer used) and this option now does
552 nothing except give a warning.
553
555 pcre2api(3), pcre2-config(3).
557
559 Philip Hazel
561 Retired from University Computing Service
562 Cambridge, England.
563
565 Last updated: 27 July 2022
567 Copyright (c) 1997-2022 University of Cambridge.
568PCRE2 10.41 27 July 2022 PCRE2BUILD(3)