--- /dev/null
+<html>
+<head>
+<title>pcre2limits specification</title>
+</head>
+<body bgcolor="#FFFFFF" text="#00005A" link="#0066FF" alink="#3399FF" vlink="#2222BB">
+<h1>pcre2limits 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 generated
+automatically from the original man page. If there is any nonsense in it,
+please consult the man page, in case the conversion went wrong.
+<br>
+<br><b>
+SIZE AND OTHER LIMITATIONS
+</b><br>
+<P>
+There are some size limitations in PCRE2 but it is hoped that they will never
+in practice be relevant.
+</P>
+<P>
+The maximum size of a compiled pattern is approximately 64 thousand code units
+for the 8-bit and 16-bit libraries if PCRE2 is compiled with the default
+internal linkage size, which is 2 bytes for these libraries. If you want to
+process regular expressions that are truly enormous, you can compile PCRE2 with
+an internal linkage size of 3 or 4 (when building the 16-bit library, 3 is
+rounded up to 4). See the <b>README</b> file in the source distribution and the
+<a href="pcre2build.html"><b>pcre2build</b></a>
+documentation for details. In these cases the limit is substantially larger.
+However, the speed of execution is slower. In the 32-bit library, the internal
+linkage size is always 4.
+</P>
+<P>
+The maximum length of a source pattern string is essentially unlimited; it is
+the largest number a PCRE2_SIZE variable can hold. However, the program that
+calls <b>pcre2_compile()</b> can specify a smaller limit.
+</P>
+<P>
+The maximum length (in code units) of a subject string is one less than the
+largest number a PCRE2_SIZE variable can hold. PCRE2_SIZE is an unsigned
+integer type, usually defined as size_t. Its maximum value (that is
+~(PCRE2_SIZE)0) is reserved as a special indicator for zero-terminated strings
+and unset offsets.
+</P>
+<P>
+All values in repeating quantifiers must be less than 65536.
+</P>
+<P>
+The maximum length of a lookbehind assertion is 65535 characters.
+</P>
+<P>
+There is no limit to the number of parenthesized subpatterns, but there can be
+no more than 65535 capturing subpatterns. There is, however, a limit to the
+depth of nesting of parenthesized subpatterns of all kinds. This is imposed in
+order to limit the amount of system stack used at compile time. The default
+limit can be specified when PCRE2 is built; if not, the default is set to 250.
+An application can change this limit by calling pcre2_set_parens_nest_limit()
+to set the limit in a compile context.
+</P>
+<P>
+The maximum length of name for a named subpattern is 32 code units, and the
+maximum number of named subpatterns is 10000.
+</P>
+<P>
+The maximum length of a name in a (*MARK), (*PRUNE), (*SKIP), or (*THEN) verb
+is 255 code units for the 8-bit library and 65535 code units for the 16-bit and
+32-bit libraries.
+</P>
+<P>
+The maximum length of a string argument to a callout is the largest number a
+32-bit unsigned integer can hold.
+</P>
+<br><b>
+AUTHOR
+</b><br>
+<P>
+Philip Hazel
+<br>
+University Computing Service
+<br>
+Cambridge, England.
+<br>
+</P>
+<br><b>
+REVISION
+</b><br>
+<P>
+Last updated: 30 March 2017
+<br>
+Copyright © 1997-2017 University of Cambridge.
+<br>
+<p>
+Return to the <a href="index.html">PCRE2 index page</a>.
+</p>
projects / ossec-hids.git / blobdiff