2 dnl Copyright (C) 2002, 2003, 2004, 2007 Free Software Foundation, Inc.
3 dnl This file is free software; the Free Software Foundation
4 dnl gives unlimited permission to copy and/or distribute it,
5 dnl with or without modifications, as long as this notice is preserved.
7 AC_DEFUN([gl_FUNC_MEMMEM],
9 dnl Persuade glibc <string.h> to declare memmem().
10 AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])
12 AC_REQUIRE([gl_HEADER_STRING_H_DEFAULTS])
13 AC_REPLACE_FUNCS(memmem)
14 AC_CHECK_DECLS_ONCE(memmem)
15 if test $ac_cv_have_decl_memmem = no; then
18 AC_CACHE_CHECK([whether memmem works], [gl_cv_func_memmem_works],
19 [AC_RUN_IFELSE([AC_LANG_PROGRAM([#include <string.h>],
20 [return !memmem ("a", 1, NULL, 0);])],
21 [gl_cv_func_memmem_works=yes], [gl_cv_func_memmem_works=no],
22 [dnl pessimistically assume the worst, since even glibc 2.6.1
23 dnl has quadratic complexity in its memmem
24 gl_cv_func_memmem_works=no])])
25 if test $gl_cv_func_memmem_works = no; then
33 # Prerequisites of lib/memmem.c.
34 AC_DEFUN([gl_PREREQ_MEMMEM], [:])