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# strcasestr.m4 serial 28
dnl Copyright (C) 2005, 2007-2023 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 strcasestr is present and works.
AC_DEFUN([gl_FUNC_STRCASESTR_SIMPLE],
[
AC_REQUIRE([gl_STRING_H_DEFAULTS])
dnl Persuade glibc <string.h> to declare strcasestr().
AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])
AC_REQUIRE([gl_FUNC_MEMCHR])
AC_CHECK_FUNCS([strcasestr])
if test $ac_cv_func_strcasestr = no; then
HAVE_STRCASESTR=0
else
if test $REPLACE_MEMCHR = 1; then
REPLACE_STRCASESTR=1
else
dnl Detect https://sourceware.org/bugzilla/show_bug.cgi?id=12092
dnl and https://sourceware.org/bugzilla/show_bug.cgi?id=23637.
AC_CACHE_CHECK([whether strcasestr works],
[gl_cv_func_strcasestr_works_always],
[AC_RUN_IFELSE(
[AC_LANG_PROGRAM([[
#include <string.h> /* for __GNU_LIBRARY__, strcasestr */
#ifdef __GNU_LIBRARY__
#include <features.h>
#if __GLIBC__ == 2 && __GLIBC_MINOR__ == 28
Unlucky user
#endif
#endif
#define P "_EF_BF_BD"
#define HAYSTACK "F_BD_CE_BD" P P P P "_C3_88_20" P P P "_C3_A7_20" P
#define NEEDLE P P P P P
]],
[[return !!strcasestr (HAYSTACK, NEEDLE);
]])],
[gl_cv_func_strcasestr_works_always=yes],
[gl_cv_func_strcasestr_works_always=no],
[dnl glibc 2.12 and cygwin 1.7.7 have a known bug. uClibc is not
dnl affected, since it uses different source code for strcasestr
dnl than glibc.
dnl Assume that it works on all other platforms, even if it is not
dnl linear.
AC_EGREP_CPP([Lucky user],
[
#include <string.h> /* for __GNU_LIBRARY__ */
#ifdef __GNU_LIBRARY__
#include <features.h>
#if ((__GLIBC__ == 2 && __GLIBC_MINOR__ > 12) || (__GLIBC__ > 2)) \
|| defined __UCLIBC__
Lucky user
#endif
#elif defined __CYGWIN__
#include <cygwin/version.h>
#if CYGWIN_VERSION_DLL_COMBINED > CYGWIN_VERSION_DLL_MAKE_COMBINED (1007, 7)
Lucky user
#endif
#else
Lucky user
#endif
],
[gl_cv_func_strcasestr_works_always="guessing yes"],
[gl_cv_func_strcasestr_works_always="$gl_cross_guess_normal"])
])
])
case "$gl_cv_func_strcasestr_works_always" in
*yes) ;;
*)
REPLACE_STRCASESTR=1
;;
esac
fi
fi
]) # gl_FUNC_STRCASESTR_SIMPLE
dnl Additionally, check that strcasestr is efficient.
AC_DEFUN([gl_FUNC_STRCASESTR],
[
AC_REQUIRE([gl_FUNC_STRCASESTR_SIMPLE])
if test $HAVE_STRCASESTR = 1 && test $REPLACE_STRCASESTR = 0; then
AC_CACHE_CHECK([whether strcasestr works in linear time],
[gl_cv_func_strcasestr_linear],
[AC_RUN_IFELSE([AC_LANG_PROGRAM([[
#include <signal.h> /* for signal */
#include <string.h> /* for strcasestr */
#include <stdlib.h> /* for malloc */
#include <unistd.h> /* for alarm */
static void quit (int sig) { _exit (sig + 128); }
]], [[
int result = 0;
size_t m = 1000000;
char *haystack = (char *) malloc (2 * m + 2);
char *needle = (char *) malloc (m + 2);
/* Failure to compile this test due to missing alarm is okay,
since all such platforms (mingw) also lack strcasestr. */
signal (SIGALRM, quit);
alarm (5);
/* Check for quadratic performance. */
if (haystack && needle)
{
memset (haystack, 'A', 2 * m);
haystack[2 * m] = 'B';
haystack[2 * m + 1] = 0;
memset (needle, 'A', m);
needle[m] = 'B';
needle[m + 1] = 0;
if (!strcasestr (haystack, needle))
result |= 1;
}
/* Free allocated memory, in case some sanitizer is watching. */
free (haystack);
free (needle);
return result;
]])],
[gl_cv_func_strcasestr_linear=yes], [gl_cv_func_strcasestr_linear=no],
[dnl Only glibc > 2.12 and cygwin > 1.7.7 are known to have a
dnl strcasestr that works in linear time.
AC_EGREP_CPP([Lucky user],
[
#include <features.h>
#ifdef __GNU_LIBRARY__
#if ((__GLIBC__ == 2 && __GLIBC_MINOR__ > 12) || (__GLIBC__ > 2)) \
&& !defined __UCLIBC__
Lucky user
#endif
#endif
#ifdef __CYGWIN__
#include <cygwin/version.h>
#if CYGWIN_VERSION_DLL_COMBINED > CYGWIN_VERSION_DLL_MAKE_COMBINED (1007, 7)
Lucky user
#endif
#endif
],
[gl_cv_func_strcasestr_linear="guessing yes"],
[gl_cv_func_strcasestr_linear="$gl_cross_guess_normal"])
])
])
case "$gl_cv_func_strcasestr_linear" in
*yes) ;;
*)
REPLACE_STRCASESTR=1
;;
esac
fi
]) # gl_FUNC_STRCASESTR
# Prerequisites of lib/strcasestr.c.
AC_DEFUN([gl_PREREQ_STRCASESTR], [
:
])
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