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# strstr.m4 serial 13
dnl Copyright (C) 2008-2011 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
dnl with or without modifications, as long as this notice is preserved.
dnl Check that strstr works.
AC_DEFUN([gl_FUNC_STRSTR_SIMPLE],
[
AC_REQUIRE([gl_HEADER_STRING_H_DEFAULTS])
AC_REQUIRE([gl_FUNC_MEMCHR])
if test "$gl_cv_func_memchr_works" != yes; then
REPLACE_STRSTR=1
AC_LIBOBJ([strstr])
else
dnl Detect http://sourceware.org/bugzilla/show_bug.cgi?id=12092.
AC_CACHE_CHECK([whether strstr works],
[gl_cv_func_strstr_works_always],
[AC_RUN_IFELSE([AC_LANG_PROGRAM([[
#include <string.h> /* for strstr */
#define P "_EF_BF_BD"
#define HAYSTACK "F_BD_CE_BD" P P P P "_C3_88_20" P P P "_C3_A7_20" P
#define NEEDLE P P P P P
]], [[return !!strstr (HAYSTACK, NEEDLE);
]])],
[gl_cv_func_strstr_works_always=yes],
[gl_cv_func_strstr_works_always=no],
[dnl glibc 2.12 and cygwin 1.7.7 have a known bug. uClibc is not
dnl affected, since it uses different source code for strstr than
dnl glibc.
dnl Assume that it works on all other platforms, even if it is not
dnl linear.
AC_EGREP_CPP([Lucky user],
[
#ifdef __GNU_LIBRARY__
#include <features.h>
#if ((__GLIBC__ == 2 && __GLIBC_MINOR__ > 12) || (__GLIBC__ > 2)) \
|| defined __UCLIBC__
Lucky user
#endif
#elif defined __CYGWIN__
#include <cygwin/version.h>
#if CYGWIN_VERSION_DLL_COMBINED > CYGWIN_VERSION_DLL_MAKE_COMBINED (1007, 7)
Lucky user
#endif
#else
Lucky user
#endif
],
[gl_cv_func_strstr_works_always=yes],
[gl_cv_func_strstr_works_always="guessing no"])
])
])
if test "$gl_cv_func_strstr_works_always" != yes; then
REPLACE_STRSTR=1
AC_LIBOBJ([strstr])
fi
fi
]) # gl_FUNC_STRSTR_SIMPLE
dnl Additionally, check that strstr is efficient.
AC_DEFUN([gl_FUNC_STRSTR],
[
AC_REQUIRE([gl_FUNC_STRSTR_SIMPLE])
if test $REPLACE_STRSTR = 0; then
AC_CACHE_CHECK([whether strstr works in linear time],
[gl_cv_func_strstr_linear],
[AC_RUN_IFELSE([AC_LANG_PROGRAM([[
#include <signal.h> /* for signal */
#include <string.h> /* for strstr */
#include <stdlib.h> /* for malloc */
#include <unistd.h> /* for alarm */
static void quit (int sig) { exit (sig + 128); }
]], [[
int result = 0;
size_t m = 1000000;
char *haystack = (char *) malloc (2 * m + 2);
char *needle = (char *) malloc (m + 2);
/* Failure to compile this test due to missing alarm is okay,
since all such platforms (mingw) also have quadratic strstr. */
signal (SIGALRM, quit);
alarm (5);
/* Check for quadratic performance. */
if (haystack && needle)
{
memset (haystack, 'A', 2 * m);
haystack[2 * m] = 'B';
haystack[2 * m + 1] = 0;
memset (needle, 'A', m);
needle[m] = 'B';
needle[m + 1] = 0;
if (!strstr (haystack, needle))
result |= 1;
}
return result;
]])],
[gl_cv_func_strstr_linear=yes], [gl_cv_func_strstr_linear=no],
[dnl Only glibc > 2.12 and cygwin > 1.7.7 are known to have a
dnl bug-free strstr that works in linear time.
AC_EGREP_CPP([Lucky user],
[
#include <features.h>
#ifdef __GNU_LIBRARY__
#if ((__GLIBC__ == 2 && __GLIBC_MINOR__ > 12) || (__GLIBC__ > 2)) \
&& !defined __UCLIBC__
Lucky user
#endif
#endif
#ifdef __CYGWIN__
#include <cygwin/version.h>
#if CYGWIN_VERSION_DLL_COMBINED > CYGWIN_VERSION_DLL_MAKE_COMBINED (1007, 7)
Lucky user
#endif
#endif
],
[gl_cv_func_strstr_linear=yes],
[gl_cv_func_strstr_linear="guessing no"])
])
])
if test "$gl_cv_func_strstr_linear" != yes; then
REPLACE_STRSTR=1
fi
fi
if test $REPLACE_STRSTR = 1; then
AC_LIBOBJ([strstr])
fi
]) # gl_FUNC_STRSTR
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