1# strcasestr.m4 serial 13
2dnl Copyright (C) 2005, 2007, 2008, 2009 Free Software Foundation, Inc.
3dnl This file is free software; the Free Software Foundation
4dnl gives unlimited permission to copy and/or distribute it,
5dnl with or without modifications, as long as this notice is preserved.
6
7dnl Check that strcasestr is present and works.
8AC_DEFUN([gl_FUNC_STRCASESTR_SIMPLE],
9[
10  AC_REQUIRE([gl_HEADER_STRING_H_DEFAULTS])
11
12  dnl Persuade glibc <string.h> to declare strcasestr().
13  AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])
14
15  AC_REQUIRE([gl_FUNC_MEMCHR])
16  AC_CHECK_FUNCS([strcasestr])
17  if test $ac_cv_func_strcasestr = no; then
18    HAVE_STRCASESTR=0
19  else
20    if test "$gl_cv_func_memchr_works" != yes; then
21      REPLACE_STRCASESTR=1
22    fi
23  fi
24  if test $HAVE_STRCASESTR = 0 || test $REPLACE_STRCASESTR = 1; then
25    AC_LIBOBJ([strcasestr])
26    gl_PREREQ_STRCASESTR
27  fi
28]) # gl_FUNC_STRCASESTR_SIMPLE
29
30dnl Additionally, check that strcasestr is efficient.
31AC_DEFUN([gl_FUNC_STRCASESTR],
32[
33  AC_REQUIRE([gl_FUNC_STRCASESTR_SIMPLE])
34  if test $HAVE_STRCASESTR = 1 && test $REPLACE_STRCASESTR = 0; then
35    AC_CACHE_CHECK([whether strcasestr works in linear time],
36      [gl_cv_func_strcasestr_linear],
37      [AC_RUN_IFELSE([AC_LANG_PROGRAM([[
38#include <signal.h> /* for signal */
39#include <string.h> /* for memmem */
40#include <stdlib.h> /* for malloc */
41#include <unistd.h> /* for alarm */
42]], [[size_t m = 1000000;
43    char *haystack = (char *) malloc (2 * m + 2);
44    char *needle = (char *) malloc (m + 2);
45    void *result = 0;
46    /* Failure to compile this test due to missing alarm is okay,
47       since all such platforms (mingw) also lack strcasestr.  */
48    signal (SIGALRM, SIG_DFL);
49    alarm (5);
50    /* Check for quadratic performance.  */
51    if (haystack && needle)
52      {
53	memset (haystack, 'A', 2 * m);
54	haystack[2 * m] = 'B';
55	haystack[2 * m + 1] = 0;
56	memset (needle, 'A', m);
57	needle[m] = 'B';
58	needle[m + 1] = 0;
59	result = strcasestr (haystack, needle);
60      }
61    return !result;]])],
62	[gl_cv_func_strcasestr_linear=yes], [gl_cv_func_strcasestr_linear=no],
63        [dnl Only glibc >= 2.9 and cygwin >= 1.7.0 are known to have a
64         dnl strcasestr that works in linear time.
65	 AC_EGREP_CPP([Lucky user],
66	   [
67#include <features.h>
68#ifdef __GNU_LIBRARY__
69 #if (__GLIBC__ == 2 && __GLIBC_MINOR__ >= 9) || (__GLIBC__ > 2)
70  Lucky user
71 #endif
72#endif
73#ifdef __CYGWIN__
74 #include <cygwin/version.h>
75 #if CYGWIN_VERSION_DLL_MAJOR >= 1007
76  Lucky user
77 #endif
78#endif
79	   ],
80	   [gl_cv_func_strcasestr_linear=yes],
81	   [gl_cv_func_strcasestr_linear="guessing no"])
82	])
83      ])
84    if test "$gl_cv_func_strcasestr_linear" != yes; then
85      REPLACE_STRCASESTR=1
86      AC_LIBOBJ([strcasestr])
87      gl_PREREQ_STRCASESTR
88    fi
89  fi
90]) # gl_FUNC_STRCASESTR
91
92# Prerequisites of lib/strcasestr.c.
93AC_DEFUN([gl_PREREQ_STRCASESTR], [
94  :
95])
96