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# wcsstr.m4 serial 3
dnl Copyright (C) 2011-2023 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 wcsstr exists and works.
AC_DEFUN([gl_FUNC_WCSSTR_SIMPLE],
[
AC_REQUIRE([gl_WCHAR_H_DEFAULTS])
AC_CHECK_FUNCS_ONCE([wcsstr])
if test $ac_cv_func_wcsstr = no; then
HAVE_WCSSTR=0
fi
])
dnl Additionally, check that wcsstr is efficient.
AC_DEFUN([gl_FUNC_WCSSTR],
[
AC_REQUIRE([gl_FUNC_WCSSTR_SIMPLE])
if test $HAVE_WCSSTR = 1; then
AC_CACHE_CHECK([whether wcsstr works in linear time],
[gl_cv_func_wcsstr_linear],
[AC_RUN_IFELSE([AC_LANG_PROGRAM([[
#include <signal.h> /* for signal */
#include <wchar.h> /* for wcsstr */
#include <stdlib.h> /* for malloc */
#include <unistd.h> /* for alarm */
static void quit (int sig) { _exit (sig + 128); }
]], [[
int result = 0;
size_t m = 1000000;
wchar_t *haystack = (wchar_t *) malloc ((2 * m + 2) * sizeof (wchar_t));
wchar_t *needle = (wchar_t *) malloc ((m + 2) * sizeof (wchar_t));
/* Failure to compile this test due to missing alarm is okay,
since all such platforms (mingw) also have quadratic strstr. */
signal (SIGALRM, quit);
alarm (5);
/* Check for quadratic performance. */
if (haystack && needle)
{
size_t i;
for (i = 0; i < 2 * m; i++)
haystack[i] = L'A';
haystack[2 * m] = L'B';
haystack[2 * m + 1] = 0;
for (i = 0; i < m; i++)
needle[i] = L'A';
needle[m] = L'B';
needle[m + 1] = 0;
if (!wcsstr (haystack, needle))
result |= 1;
}
/* Free allocated memory, in case some sanitizer is watching. */
free (haystack);
free (needle);
return result;
]])],
[gl_cv_func_wcsstr_linear=yes], [gl_cv_func_wcsstr_linear=no],
[gl_cv_func_wcsstr_linear="$gl_cross_guess_normal"])
])
case "$gl_cv_func_wcsstr_linear" in
*yes) ;;
*)
REPLACE_WCSSTR=1
;;
esac
fi
if test $HAVE_WCSSTR = 0 || test $REPLACE_WCSSTR = 1; then
AC_DEFINE([NEED_LINEAR_WCSSTR], [1],
[Define to 1 to get a worst-case linear time implementation of wcsstr.])
fi
])
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