1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
|
# memmem.m4 serial 25
dnl Copyright (C) 2002-2004, 2007-2017 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 memmem is present and functional.
AC_DEFUN([gl_FUNC_MEMMEM_SIMPLE],
[
dnl Persuade glibc <string.h> to declare memmem().
AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])
AC_REQUIRE([gl_HEADER_STRING_H_DEFAULTS])
AC_CHECK_FUNCS([memmem])
if test $ac_cv_func_memmem = yes; then
HAVE_MEMMEM=1
else
HAVE_MEMMEM=0
fi
AC_CHECK_DECLS_ONCE([memmem])
if test $ac_cv_have_decl_memmem = no; then
HAVE_DECL_MEMMEM=0
else
dnl Detect http://sourceware.org/bugzilla/show_bug.cgi?id=12092.
dnl Also check that we handle empty needles correctly.
AC_CACHE_CHECK([whether memmem works],
[gl_cv_func_memmem_works_always],
[AC_RUN_IFELSE([AC_LANG_PROGRAM([[
#include <string.h> /* for memmem */
#define P "_EF_BF_BD"
#define HAYSTACK "F_BD_CE_BD" P P P P "_C3_88_20" P P P "_C3_A7_20" P
#define NEEDLE P P P P P
]], [[
int result = 0;
if (memmem (HAYSTACK, strlen (HAYSTACK), NEEDLE, strlen (NEEDLE)))
result |= 1;
/* Check for empty needle behavior. */
{
const char *haystack = "AAA";
if (memmem (haystack, 3, NULL, 0) != haystack)
result |= 2;
}
return result;
]])],
[gl_cv_func_memmem_works_always=yes],
[gl_cv_func_memmem_works_always=no],
[dnl glibc 2.9..2.12 and cygwin 1.7.7 have issue #12092 above.
dnl Also empty needles work on glibc >= 2.1 and cygwin >= 1.7.0.
dnl uClibc is not affected, since it uses different source code.
dnl Assume that it works on all other platforms (even if not linear).
AC_EGREP_CPP([Lucky user],
[
#ifdef __GNU_LIBRARY__
#include <features.h>
#if ((__GLIBC__ == 2 && ((__GLIBC_MINOR > 0 && __GLIBC_MINOR__ < 9) \
|| __GLIBC_MINOR__ > 12)) \
|| (__GLIBC__ > 2)) \
|| defined __UCLIBC__
Lucky user
#endif
#elif defined __CYGWIN__
#include <cygwin/version.h>
#if CYGWIN_VERSION_DLL_COMBINED > CYGWIN_VERSION_DLL_MAKE_COMBINED (1007, 7)
Lucky user
#endif
#else
Lucky user
#endif
],
[gl_cv_func_memmem_works_always="guessing yes"],
[gl_cv_func_memmem_works_always="guessing no"])
])
])
case "$gl_cv_func_memmem_works_always" in
*yes) ;;
*)
REPLACE_MEMMEM=1
;;
esac
fi
gl_PREREQ_MEMMEM
]) # gl_FUNC_MEMMEM_SIMPLE
dnl Additionally, check that memmem has linear performance characteristics
AC_DEFUN([gl_FUNC_MEMMEM],
[
AC_REQUIRE([gl_FUNC_MEMMEM_SIMPLE])
if test $HAVE_DECL_MEMMEM = 1 && test $REPLACE_MEMMEM = 0; then
AC_CACHE_CHECK([whether memmem works in linear time],
[gl_cv_func_memmem_works_fast],
[AC_RUN_IFELSE([AC_LANG_PROGRAM([[
#include <signal.h> /* for signal */
#include <string.h> /* for memmem */
#include <stdlib.h> /* for malloc */
#include <unistd.h> /* for alarm */
static void quit (int sig) { _exit (sig + 128); }
]], [[
int result = 0;
size_t m = 1000000;
char *haystack = (char *) malloc (2 * m + 1);
char *needle = (char *) malloc (m + 1);
/* Failure to compile this test due to missing alarm is okay,
since all such platforms (mingw) also lack memmem. */
signal (SIGALRM, quit);
alarm (5);
/* Check for quadratic performance. */
if (haystack && needle)
{
memset (haystack, 'A', 2 * m);
haystack[2 * m] = 'B';
memset (needle, 'A', m);
needle[m] = 'B';
if (!memmem (haystack, 2 * m + 1, needle, m + 1))
result |= 1;
}
/* Free allocated memory, in case some sanitizer is watching. */
free (haystack);
free (needle);
return result;
]])],
[gl_cv_func_memmem_works_fast=yes], [gl_cv_func_memmem_works_fast=no],
[dnl Only glibc >= 2.9 and cygwin > 1.7.0 are known to have a
dnl memmem that works in linear time.
AC_EGREP_CPP([Lucky user],
[
#include <features.h>
#ifdef __GNU_LIBRARY__
#if ((__GLIBC__ == 2 && __GLIBC_MINOR__ >= 9) || (__GLIBC__ > 2)) \
&& !defined __UCLIBC__
Lucky user
#endif
#endif
#ifdef __CYGWIN__
#include <cygwin/version.h>
#if CYGWIN_VERSION_DLL_COMBINED > CYGWIN_VERSION_DLL_MAKE_COMBINED (1007, 0)
Lucky user
#endif
#endif
],
[gl_cv_func_memmem_works_fast="guessing yes"],
[gl_cv_func_memmem_works_fast="guessing no"])
])
])
case "$gl_cv_func_memmem_works_fast" in
*yes) ;;
*)
REPLACE_MEMMEM=1
;;
esac
fi
]) # gl_FUNC_MEMMEM
# Prerequisites of lib/memmem.c.
AC_DEFUN([gl_PREREQ_MEMMEM], [:])
|
