1# strcasestr.m4 serial 21
2dnl Copyright (C) 2005, 2007-2014 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    else
23      dnl Detect http://sourceware.org/bugzilla/show_bug.cgi?id=12092.
24      AC_CACHE_CHECK([whether strcasestr works],
25        [gl_cv_func_strcasestr_works_always],
26        [AC_RUN_IFELSE([AC_LANG_PROGRAM([[
27#include <string.h> /* for strcasestr */
28#define P "_EF_BF_BD"
29#define HAYSTACK "F_BD_CE_BD" P P P P "_C3_88_20" P P P "_C3_A7_20" P
30#define NEEDLE P P P P P
31]], [[return !!strcasestr (HAYSTACK, NEEDLE);
32      ]])],
33          [gl_cv_func_strcasestr_works_always=yes],
34          [gl_cv_func_strcasestr_works_always=no],
35          [dnl glibc 2.12 and cygwin 1.7.7 have a known bug.  uClibc is not
36           dnl affected, since it uses different source code for strcasestr
37           dnl than glibc.
38           dnl Assume that it works on all other platforms, even if it is not
39           dnl linear.
40           AC_EGREP_CPP([Lucky user],
41             [
42#ifdef __GNU_LIBRARY__
43 #include <features.h>
44 #if ((__GLIBC__ == 2 && __GLIBC_MINOR__ > 12) || (__GLIBC__ > 2)) \
45     || defined __UCLIBC__
46  Lucky user
47 #endif
48#elif defined __CYGWIN__
49 #include <cygwin/version.h>
50 #if CYGWIN_VERSION_DLL_COMBINED > CYGWIN_VERSION_DLL_MAKE_COMBINED (1007, 7)
51  Lucky user
52 #endif
53#else
54  Lucky user
55#endif
56             ],
57             [gl_cv_func_strcasestr_works_always="guessing yes"],
58             [gl_cv_func_strcasestr_works_always="guessing no"])
59          ])
60        ])
61      case "$gl_cv_func_strcasestr_works_always" in
62        *yes) ;;
63        *)
64          REPLACE_STRCASESTR=1
65          ;;
66      esac
67    fi
68  fi
69]) # gl_FUNC_STRCASESTR_SIMPLE
70
71dnl Additionally, check that strcasestr is efficient.
72AC_DEFUN([gl_FUNC_STRCASESTR],
73[
74  AC_REQUIRE([gl_FUNC_STRCASESTR_SIMPLE])
75  if test $HAVE_STRCASESTR = 1 && test $REPLACE_STRCASESTR = 0; then
76    AC_CACHE_CHECK([whether strcasestr works in linear time],
77      [gl_cv_func_strcasestr_linear],
78      [AC_RUN_IFELSE([AC_LANG_PROGRAM([[
79#include <signal.h> /* for signal */
80#include <string.h> /* for strcasestr */
81#include <stdlib.h> /* for malloc */
82#include <unistd.h> /* for alarm */
83static void quit (int sig) { exit (sig + 128); }
84]], [[
85    int result = 0;
86    size_t m = 1000000;
87    char *haystack = (char *) malloc (2 * m + 2);
88    char *needle = (char *) malloc (m + 2);
89    /* Failure to compile this test due to missing alarm is okay,
90       since all such platforms (mingw) also lack strcasestr.  */
91    signal (SIGALRM, quit);
92    alarm (5);
93    /* Check for quadratic performance.  */
94    if (haystack && needle)
95      {
96        memset (haystack, 'A', 2 * m);
97        haystack[2 * m] = 'B';
98        haystack[2 * m + 1] = 0;
99        memset (needle, 'A', m);
100        needle[m] = 'B';
101        needle[m + 1] = 0;
102        if (!strcasestr (haystack, needle))
103          result |= 1;
104      }
105    return result;
106    ]])],
107        [gl_cv_func_strcasestr_linear=yes], [gl_cv_func_strcasestr_linear=no],
108        [dnl Only glibc > 2.12 and cygwin > 1.7.7 are known to have a
109         dnl strcasestr that works in linear time.
110         AC_EGREP_CPP([Lucky user],
111           [
112#include <features.h>
113#ifdef __GNU_LIBRARY__
114 #if ((__GLIBC__ == 2 && __GLIBC_MINOR__ > 12) || (__GLIBC__ > 2)) \
115     && !defined __UCLIBC__
116  Lucky user
117 #endif
118#endif
119#ifdef __CYGWIN__
120 #include <cygwin/version.h>
121 #if CYGWIN_VERSION_DLL_COMBINED > CYGWIN_VERSION_DLL_MAKE_COMBINED (1007, 7)
122  Lucky user
123 #endif
124#endif
125           ],
126           [gl_cv_func_strcasestr_linear="guessing yes"],
127           [gl_cv_func_strcasestr_linear="guessing no"])
128        ])
129      ])
130    case "$gl_cv_func_strcasestr_linear" in
131      *yes) ;;
132      *)
133        REPLACE_STRCASESTR=1
134        ;;
135    esac
136  fi
137]) # gl_FUNC_STRCASESTR
138
139# Prerequisites of lib/strcasestr.c.
140AC_DEFUN([gl_PREREQ_STRCASESTR], [
141  :
142])
143