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3  <title>pcrebuild specification</title>  <title>pcrebuild specification</title>
4  </head>  </head>
5  <body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">  <body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
6  This HTML document has been generated automatically from the original man page.  <h1>pcrebuild man page</h1>
7  If there is any nonsense in it, please consult the man page, in case the  <p>
8  conversion went wrong.<br>  Return to the <a href="index.html">PCRE index page</a>.
9    </p>
10    <p>
11    This page is part of the PCRE HTML documentation. It was generated automatically
12    from the original man page. If there is any nonsense in it, please consult the
13    man page, in case the conversion went wrong.
14    <br>
15  <ul>  <ul>
16  <li><a name="TOC1" href="#SEC1">PCRE BUILD-TIME OPTIONS</a>  <li><a name="TOC1" href="#SEC1">PCRE BUILD-TIME OPTIONS</a>
17  <li><a name="TOC2" href="#SEC2">UTF-8 SUPPORT</a>  <li><a name="TOC2" href="#SEC2">C++ SUPPORT</a>
18  <li><a name="TOC3" href="#SEC3">CODE VALUE OF NEWLINE</a>  <li><a name="TOC3" href="#SEC3">UTF-8 SUPPORT</a>
19  <li><a name="TOC4" href="#SEC4">BUILDING SHARED AND STATIC LIBRARIES</a>  <li><a name="TOC4" href="#SEC4">UNICODE CHARACTER PROPERTY SUPPORT</a>
20  <li><a name="TOC5" href="#SEC5">POSIX MALLOC USAGE</a>  <li><a name="TOC5" href="#SEC5">CODE VALUE OF NEWLINE</a>
21  <li><a name="TOC6" href="#SEC6">LIMITING PCRE RESOURCE USAGE</a>  <li><a name="TOC6" href="#SEC6">BUILDING SHARED AND STATIC LIBRARIES</a>
22  <li><a name="TOC7" href="#SEC7">HANDLING VERY LARGE PATTERNS</a>  <li><a name="TOC7" href="#SEC7">POSIX MALLOC USAGE</a>
23  <li><a name="TOC8" href="#SEC8">AVOIDING EXCESSIVE STACK USAGE</a>  <li><a name="TOC8" href="#SEC8">HANDLING VERY LARGE PATTERNS</a>
24  <li><a name="TOC9" href="#SEC9">USING EBCDIC CODE</a>  <li><a name="TOC9" href="#SEC9">AVOIDING EXCESSIVE STACK USAGE</a>
25    <li><a name="TOC10" href="#SEC10">LIMITING PCRE RESOURCE USAGE</a>
26    <li><a name="TOC11" href="#SEC11">USING EBCDIC CODE</a>
27  </ul>  </ul>
28  <br><a name="SEC1" href="#TOC1">PCRE BUILD-TIME OPTIONS</a><br>  <br><a name="SEC1" href="#TOC1">PCRE BUILD-TIME OPTIONS</a><br>
29  <P>  <P>
30  This document describes the optional features of PCRE that can be selected when  This document describes the optional features of PCRE that can be selected when
31  the library is compiled. They are all selected, or deselected, by providing  the library is compiled. They are all selected, or deselected, by providing
32  options to the <b>configure</b> script which is run before the <b>make</b>  options to the <b>configure</b> script that is run before the <b>make</b>
33  command. The complete list of options for <b>configure</b> (which includes the  command. The complete list of options for <b>configure</b> (which includes the
34  standard ones such as the selection of the installation directory) can be  standard ones such as the selection of the installation directory) can be
35  obtained by running  obtained by running
 </P>  
 <P>  
36  <pre>  <pre>
37    ./configure --help    ./configure --help
38  </PRE>  </pre>
 </P>  
 <P>  
39  The following sections describe certain options whose names begin with --enable  The following sections describe certain options whose names begin with --enable
40  or --disable. These settings specify changes to the defaults for the  or --disable. These settings specify changes to the defaults for the
41  <b>configure</b> command. Because of the way that <b>configure</b> works,  <b>configure</b> command. Because of the way that <b>configure</b> works,
42  --enable and --disable always come in pairs, so the complementary option always  --enable and --disable always come in pairs, so the complementary option always
43  exists as well, but as it specifies the default, it is not described.  exists as well, but as it specifies the default, it is not described.
44  </P>  </P>
45  <br><a name="SEC2" href="#TOC1">UTF-8 SUPPORT</a><br>  <br><a name="SEC2" href="#TOC1">C++ SUPPORT</a><br>
46  <P>  <P>
47  To build PCRE with support for UTF-8 character strings, add  By default, the <b>configure</b> script will search for a C++ compiler and C++
48    header files. If it finds them, it automatically builds the C++ wrapper library
49    for PCRE. You can disable this by adding
50    <pre>
51      --disable-cpp
52    </pre>
53    to the <b>configure</b> command.
54  </P>  </P>
55    <br><a name="SEC3" href="#TOC1">UTF-8 SUPPORT</a><br>
56  <P>  <P>
57    To build PCRE with support for UTF-8 character strings, add
58  <pre>  <pre>
59    --enable-utf8    --enable-utf8
60  </PRE>  </pre>
 </P>  
 <P>  
61  to the <b>configure</b> command. Of itself, this does not make PCRE treat  to the <b>configure</b> command. Of itself, this does not make PCRE treat
62  strings as UTF-8. As well as compiling PCRE with this option, you also have  strings as UTF-8. As well as compiling PCRE with this option, you also have
63  have to set the PCRE_UTF8 option when you call the <b>pcre_compile()</b>  have to set the PCRE_UTF8 option when you call the <b>pcre_compile()</b>
64  function.  function.
65  </P>  </P>
66  <br><a name="SEC3" href="#TOC1">CODE VALUE OF NEWLINE</a><br>  <br><a name="SEC4" href="#TOC1">UNICODE CHARACTER PROPERTY SUPPORT</a><br>
 <P>  
 By default, PCRE treats character 10 (linefeed) as the newline character. This  
 is the normal newline character on Unix-like systems. You can compile PCRE to  
 use character 13 (carriage return) instead by adding  
 </P>  
67  <P>  <P>
68    UTF-8 support allows PCRE to process character values greater than 255 in the
69    strings that it handles. On its own, however, it does not provide any
70    facilities for accessing the properties of such characters. If you want to be
71    able to use the pattern escapes \P, \p, and \X, which refer to Unicode
72    character properties, you must add
73    <pre>
74      --enable-unicode-properties
75    </pre>
76    to the <b>configure</b> command. This implies UTF-8 support, even if you have
77    not explicitly requested it.
78    </P>
79    <P>
80    Including Unicode property support adds around 90K of tables to the PCRE
81    library, approximately doubling its size. Only the general category properties
82    such as <i>Lu</i> and <i>Nd</i> are supported. Details are given in the
83    <a href="pcrepattern.html"><b>pcrepattern</b></a>
84    documentation.
85    </P>
86    <br><a name="SEC5" href="#TOC1">CODE VALUE OF NEWLINE</a><br>
87    <P>
88    By default, PCRE interprets character 10 (linefeed, LF) as indicating the end
89    of a line. This is the normal newline character on Unix-like systems. You can
90    compile PCRE to use character 13 (carriage return, CR) instead, by adding
91  <pre>  <pre>
92    --enable-newline-is-cr    --enable-newline-is-cr
93  </PRE>  </pre>
94  </P>  to the <b>configure</b> command. There is also a --enable-newline-is-lf option,
95  <P>  which explicitly specifies linefeed as the newline character.
96  to the <b>configure</b> command. For completeness there is also a  <br>
97  --enable-newline-is-lf option, which explicitly specifies linefeed as the  <br>
98  newline character.  Alternatively, you can specify that line endings are to be indicated by the two
99    character sequence CRLF. If you want this, add
100    <pre>
101      --enable-newline-is-crlf
102    </pre>
103    to the <b>configure</b> command. Whatever line ending convention is selected
104    when PCRE is built can be overridden when the library functions are called. At
105    build time it is conventional to use the standard for your operating system.
106  </P>  </P>
107  <br><a name="SEC4" href="#TOC1">BUILDING SHARED AND STATIC LIBRARIES</a><br>  <br><a name="SEC6" href="#TOC1">BUILDING SHARED AND STATIC LIBRARIES</a><br>
108  <P>  <P>
109  The PCRE building process uses <b>libtool</b> to build both shared and static  The PCRE building process uses <b>libtool</b> to build both shared and static
110  Unix libraries by default. You can suppress one of these by adding one of  Unix libraries by default. You can suppress one of these by adding one of
 </P>  
 <P>  
111  <pre>  <pre>
112    --disable-shared    --disable-shared
113    --disable-static    --disable-static
114  </PRE>  </pre>
 </P>  
 <P>  
115  to the <b>configure</b> command, as required.  to the <b>configure</b> command, as required.
116  </P>  </P>
117  <br><a name="SEC5" href="#TOC1">POSIX MALLOC USAGE</a><br>  <br><a name="SEC7" href="#TOC1">POSIX MALLOC USAGE</a><br>
118  <P>  <P>
119  When PCRE is called through the POSIX interface (see the <b>pcreposix</b>  When PCRE is called through the POSIX interface (see the
120    <a href="pcreposix.html"><b>pcreposix</b></a>
121  documentation), additional working storage is required for holding the pointers  documentation), additional working storage is required for holding the pointers
122  to capturing substrings because PCRE requires three integers per substring,  to capturing substrings, because PCRE requires three integers per substring,
123  whereas the POSIX interface provides only two. If the number of expected  whereas the POSIX interface provides only two. If the number of expected
124  substrings is small, the wrapper function uses space on the stack, because this  substrings is small, the wrapper function uses space on the stack, because this
125  is faster than using <b>malloc()</b> for each call. The default threshold above  is faster than using <b>malloc()</b> for each call. The default threshold above
126  which the stack is no longer used is 10; it can be changed by adding a setting  which the stack is no longer used is 10; it can be changed by adding a setting
127  such as  such as
 </P>  
 <P>  
128  <pre>  <pre>
129    --with-posix-malloc-threshold=20    --with-posix-malloc-threshold=20
130  </PRE>  </pre>
 </P>  
 <P>  
131  to the <b>configure</b> command.  to the <b>configure</b> command.
132  </P>  </P>
133  <br><a name="SEC6" href="#TOC1">LIMITING PCRE RESOURCE USAGE</a><br>  <br><a name="SEC8" href="#TOC1">HANDLING VERY LARGE PATTERNS</a><br>
 <P>  
 Internally, PCRE has a function called <b>match()</b> which it calls repeatedly  
 (possibly recursively) when performing a matching operation. By limiting the  
 number of times this function may be called, a limit can be placed on the  
 resources used by a single call to <b>pcre_exec()</b>. The limit can be changed  
 at run time, as described in the <b>pcreapi</b> documentation. The default is 10  
 million, but this can be changed by adding a setting such as  
 </P>  
 <P>  
 <pre>  
   --with-match-limit=500000  
 </PRE>  
 </P>  
 <P>  
 to the <b>configure</b> command.  
 </P>  
 <br><a name="SEC7" href="#TOC1">HANDLING VERY LARGE PATTERNS</a><br>  
134  <P>  <P>
135  Within a compiled pattern, offset values are used to point from one part to  Within a compiled pattern, offset values are used to point from one part to
136  another (for example, from an opening parenthesis to an alternation  another (for example, from an opening parenthesis to an alternation
137  metacharacter). By default two-byte values are used for these offsets, leading  metacharacter). By default, two-byte values are used for these offsets, leading
138  to a maximum size for a compiled pattern of around 64K. This is sufficient to  to a maximum size for a compiled pattern of around 64K. This is sufficient to
139  handle all but the most gigantic patterns. Nevertheless, some people do want to  handle all but the most gigantic patterns. Nevertheless, some people do want to
140  process enormous patterns, so it is possible to compile PCRE to use three-byte  process enormous patterns, so it is possible to compile PCRE to use three-byte
141  or four-byte offsets by adding a setting such as  or four-byte offsets by adding a setting such as
 </P>  
 <P>  
142  <pre>  <pre>
143    --with-link-size=3    --with-link-size=3
144  </PRE>  </pre>
 </P>  
 <P>  
145  to the <b>configure</b> command. The value given must be 2, 3, or 4. Using  to the <b>configure</b> command. The value given must be 2, 3, or 4. Using
146  longer offsets slows down the operation of PCRE because it has to load  longer offsets slows down the operation of PCRE because it has to load
147  additional bytes when handling them.  additional bytes when handling them.
# Line 144  If you build PCRE with an increased link Line 151  If you build PCRE with an increased link
151  using UTF-8) will fail. Part of the output of these tests is a representation  using UTF-8) will fail. Part of the output of these tests is a representation
152  of the compiled pattern, and this changes with the link size.  of the compiled pattern, and this changes with the link size.
153  </P>  </P>
154  <br><a name="SEC8" href="#TOC1">AVOIDING EXCESSIVE STACK USAGE</a><br>  <br><a name="SEC9" href="#TOC1">AVOIDING EXCESSIVE STACK USAGE</a><br>
155  <P>  <P>
156  PCRE implements backtracking while matching by making recursive calls to an  When matching with the <b>pcre_exec()</b> function, PCRE implements backtracking
157  internal function called <b>match()</b>. In environments where the size of the  by making recursive calls to an internal function called <b>match()</b>. In
158  stack is limited, this can severely limit PCRE's operation. (The Unix  environments where the size of the stack is limited, this can severely limit
159  environment does not usually suffer from this problem.) An alternative approach  PCRE's operation. (The Unix environment does not usually suffer from this
160  that uses memory from the heap to remember data, instead of using recursive  problem, but it may sometimes be necessary to increase the maximum stack size.
161  function calls, has been implemented to work round this problem. If you want to  There is a discussion in the
162    <a href="pcrestack.html"><b>pcrestack</b></a>
163    documentation.) An alternative approach to recursion that uses memory from the
164    heap to remember data, instead of using recursive function calls, has been
165    implemented to work round the problem of limited stack size. If you want to
166  build a version of PCRE that works this way, add  build a version of PCRE that works this way, add
 </P>  
 <P>  
167  <pre>  <pre>
168    --disable-stack-for-recursion    --disable-stack-for-recursion
169  </PRE>  </pre>
 </P>  
 <P>  
170  to the <b>configure</b> command. With this configuration, PCRE will use the  to the <b>configure</b> command. With this configuration, PCRE will use the
171  <b>pcre_stack_malloc</b> and <b>pcre_stack_free</b> variables to call memory  <b>pcre_stack_malloc</b> and <b>pcre_stack_free</b> variables to call memory
172  management functions. Separate functions are provided because the usage is very  management functions. Separate functions are provided because the usage is very
# Line 167  predictable: the block sizes requested a Line 174  predictable: the block sizes requested a
174  always freed in reverse order. A calling program might be able to implement  always freed in reverse order. A calling program might be able to implement
175  optimized functions that perform better than the standard <b>malloc()</b> and  optimized functions that perform better than the standard <b>malloc()</b> and
176  <b>free()</b> functions. PCRE runs noticeably more slowly when built in this  <b>free()</b> functions. PCRE runs noticeably more slowly when built in this
177  way.  way. This option affects only the <b>pcre_exec()</b> function; it is not
178    relevant for the the <b>pcre_dfa_exec()</b> function.
179  </P>  </P>
180  <br><a name="SEC9" href="#TOC1">USING EBCDIC CODE</a><br>  <br><a name="SEC10" href="#TOC1">LIMITING PCRE RESOURCE USAGE</a><br>
181  <P>  <P>
182  PCRE assumes by default that it will run in an environment where the character  Internally, PCRE has a function called <b>match()</b>, which it calls repeatedly
183  code is ASCII (or UTF-8, which is a superset of ASCII). PCRE can, however, be  (sometimes recursively) when matching a pattern with the <b>pcre_exec()</b>
184  compiled to run in an EBCDIC environment by adding  function. By controlling the maximum number of times this function may be
185    called during a single matching operation, a limit can be placed on the
186    resources used by a single call to <b>pcre_exec()</b>. The limit can be changed
187    at run time, as described in the
188    <a href="pcreapi.html"><b>pcreapi</b></a>
189    documentation. The default is 10 million, but this can be changed by adding a
190    setting such as
191    <pre>
192      --with-match-limit=500000
193    </pre>
194    to the <b>configure</b> command. This setting has no effect on the
195    <b>pcre_dfa_exec()</b> matching function.
196    </P>
197    <P>
198    In some environments it is desirable to limit the depth of recursive calls of
199    <b>match()</b> more strictly than the total number of calls, in order to
200    restrict the maximum amount of stack (or heap, if --disable-stack-for-recursion
201    is specified) that is used. A second limit controls this; it defaults to the
202    value that is set for --with-match-limit, which imposes no additional
203    constraints. However, you can set a lower limit by adding, for example,
204    <pre>
205      --with-match-limit-recursion=10000
206    </pre>
207    to the <b>configure</b> command. This value can also be overridden at run time.
208  </P>  </P>
209    <br><a name="SEC11" href="#TOC1">USING EBCDIC CODE</a><br>
210  <P>  <P>
211    PCRE assumes by default that it will run in an environment where the character
212    code is ASCII (or Unicode, which is a superset of ASCII). PCRE can, however, be
213    compiled to run in an EBCDIC environment by adding
214  <pre>  <pre>
215    --enable-ebcdic    --enable-ebcdic
216  </PRE>  </pre>
 </P>  
 <P>  
217  to the <b>configure</b> command.  to the <b>configure</b> command.
218  </P>  </P>
219  <P>  <P>
220  Last updated: 09 December 2003  Last updated: 06 June 2006
221  <br>  <br>
222  Copyright &copy; 1997-2003 University of Cambridge.  Copyright &copy; 1997-2006 University of Cambridge.
223    <p>
224    Return to the <a href="index.html">PCRE index page</a>.
225    </p>

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