2 dnl Copyright (C) 2008, 2009 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 dnl Check that strstr works.
8 AC_DEFUN([gl_FUNC_STRSTR_SIMPLE],
10 AC_REQUIRE([gl_HEADER_STRING_H_DEFAULTS])
11 AC_REQUIRE([gl_FUNC_MEMCHR])
12 if test "$gl_cv_func_memchr_works" != yes; then
16 ]) # gl_FUNC_STRSTR_SIMPLE
18 dnl Additionally, check that strstr is efficient.
19 AC_DEFUN([gl_FUNC_STRSTR],
21 AC_REQUIRE([gl_FUNC_STRSTR_SIMPLE])
22 AC_CACHE_CHECK([whether strstr works in linear time],
23 [gl_cv_func_strstr_linear],
24 [AC_RUN_IFELSE([AC_LANG_PROGRAM([[
25 #include <signal.h> /* for signal */
26 #include <string.h> /* for memmem */
27 #include <stdlib.h> /* for malloc */
28 #include <unistd.h> /* for alarm */
29 ]], [[size_t m = 1000000;
30 char *haystack = (char *) malloc (2 * m + 2);
31 char *needle = (char *) malloc (m + 2);
33 /* Failure to compile this test due to missing alarm is okay,
34 since all such platforms (mingw) also have quadratic strstr. */
35 signal (SIGALRM, SIG_DFL);
37 /* Check for quadratic performance. */
38 if (haystack && needle)
40 memset (haystack, 'A', 2 * m);
41 haystack[2 * m] = 'B';
42 haystack[2 * m + 1] = 0;
43 memset (needle, 'A', m);
46 result = strstr (haystack, needle);
49 [gl_cv_func_strstr_linear=yes], [gl_cv_func_strstr_linear=no],
50 [dnl Only glibc >= 2.9 and cygwin >= 1.7.0 are known to have a
51 dnl strstr that works in linear time.
52 AC_EGREP_CPP([Lucky user],
55 #ifdef __GNU_LIBRARY__
56 #if (__GLIBC__ == 2 && __GLIBC_MINOR__ >= 9) || (__GLIBC__ > 2)
61 #include <cygwin/version.h>
62 #if CYGWIN_VERSION_DLL_MAJOR >= 1007
67 [gl_cv_func_strstr_linear=yes],
68 [gl_cv_func_strstr_linear="guessing no"])
71 if test "$gl_cv_func_strstr_linear" != yes; then