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770d76d7 PA |
1 | # memmem.m4 serial 23 |
2 | dnl Copyright (C) 2002-2004, 2007-2012 Free Software Foundation, Inc. | |
f6ea5628 DJ |
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. | |
6 | ||
770d76d7 | 7 | dnl Check that memmem is present and functional. |
f6ea5628 DJ |
8 | AC_DEFUN([gl_FUNC_MEMMEM_SIMPLE], |
9 | [ | |
10 | dnl Persuade glibc <string.h> to declare memmem(). | |
11 | AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS]) | |
12 | ||
13 | AC_REQUIRE([gl_HEADER_STRING_H_DEFAULTS]) | |
770d76d7 PA |
14 | AC_CHECK_FUNCS([memmem]) |
15 | if test $ac_cv_func_memmem = yes; then | |
16 | HAVE_MEMMEM=1 | |
17 | else | |
18 | HAVE_MEMMEM=0 | |
19 | fi | |
f434ba03 | 20 | AC_CHECK_DECLS_ONCE([memmem]) |
f6ea5628 DJ |
21 | if test $ac_cv_have_decl_memmem = no; then |
22 | HAVE_DECL_MEMMEM=0 | |
770d76d7 PA |
23 | else |
24 | dnl Detect http://sourceware.org/bugzilla/show_bug.cgi?id=12092. | |
25 | dnl Also check that we handle empty needles correctly. | |
26 | AC_CACHE_CHECK([whether memmem works], | |
27 | [gl_cv_func_memmem_works_always], | |
28 | [AC_RUN_IFELSE([AC_LANG_PROGRAM([[ | |
29 | #include <string.h> /* for memmem */ | |
30 | #define P "_EF_BF_BD" | |
31 | #define HAYSTACK "F_BD_CE_BD" P P P P "_C3_88_20" P P P "_C3_A7_20" P | |
32 | #define NEEDLE P P P P P | |
33 | ]], [[ | |
34 | int result = 0; | |
35 | if (memmem (HAYSTACK, strlen (HAYSTACK), NEEDLE, strlen (NEEDLE))) | |
36 | result |= 1; | |
37 | /* Check for empty needle behavior. */ | |
38 | { | |
39 | const char *haystack = "AAA"; | |
40 | if (memmem (haystack, 3, NULL, 0) != haystack) | |
41 | result |= 2; | |
42 | } | |
43 | return result; | |
44 | ]])], | |
45 | [gl_cv_func_memmem_works_always=yes], | |
46 | [gl_cv_func_memmem_works_always=no], | |
47 | [dnl glibc 2.9..2.12 and cygwin 1.7.7 have issue #12092 above. | |
48 | dnl Also empty needles work on glibc >= 2.1 and cygwin >= 1.7.0. | |
49 | dnl uClibc is not affected, since it uses different source code. | |
50 | dnl Assume that it works on all other platforms (even if not linear). | |
51 | AC_EGREP_CPP([Lucky user], | |
52 | [ | |
53 | #ifdef __GNU_LIBRARY__ | |
54 | #include <features.h> | |
55 | #if ((__GLIBC__ == 2 && ((__GLIBC_MINOR > 0 && __GLIBC_MINOR__ < 9) \ | |
56 | || __GLIBC_MINOR__ > 12)) \ | |
57 | || (__GLIBC__ > 2)) \ | |
58 | || defined __UCLIBC__ | |
59 | Lucky user | |
60 | #endif | |
61 | #elif defined __CYGWIN__ | |
62 | #include <cygwin/version.h> | |
63 | #if CYGWIN_VERSION_DLL_COMBINED > CYGWIN_VERSION_DLL_MAKE_COMBINED (1007, 7) | |
64 | Lucky user | |
65 | #endif | |
66 | #else | |
67 | Lucky user | |
68 | #endif | |
69 | ], | |
70 | [gl_cv_func_memmem_works_always=yes], | |
71 | [gl_cv_func_memmem_works_always="guessing no"]) | |
72 | ]) | |
73 | ]) | |
74 | if test "$gl_cv_func_memmem_works_always" != yes; then | |
75 | REPLACE_MEMMEM=1 | |
76 | fi | |
f6ea5628 DJ |
77 | fi |
78 | gl_PREREQ_MEMMEM | |
79 | ]) # gl_FUNC_MEMMEM_SIMPLE | |
80 | ||
770d76d7 | 81 | dnl Additionally, check that memmem has linear performance characteristics |
f6ea5628 DJ |
82 | AC_DEFUN([gl_FUNC_MEMMEM], |
83 | [ | |
84 | AC_REQUIRE([gl_FUNC_MEMMEM_SIMPLE]) | |
770d76d7 | 85 | if test $HAVE_DECL_MEMMEM = 1 && test $REPLACE_MEMMEM = 0; then |
f6ea5628 | 86 | AC_CACHE_CHECK([whether memmem works in linear time], |
770d76d7 | 87 | [gl_cv_func_memmem_works_fast], |
f434ba03 PA |
88 | [AC_RUN_IFELSE([AC_LANG_PROGRAM([[ |
89 | #include <signal.h> /* for signal */ | |
f6ea5628 DJ |
90 | #include <string.h> /* for memmem */ |
91 | #include <stdlib.h> /* for malloc */ | |
92 | #include <unistd.h> /* for alarm */ | |
770d76d7 PA |
93 | static void quit (int sig) { exit (sig + 128); } |
94 | ]], [[ | |
95 | int result = 0; | |
96 | size_t m = 1000000; | |
f6ea5628 DJ |
97 | char *haystack = (char *) malloc (2 * m + 1); |
98 | char *needle = (char *) malloc (m + 1); | |
f6ea5628 DJ |
99 | /* Failure to compile this test due to missing alarm is okay, |
100 | since all such platforms (mingw) also lack memmem. */ | |
770d76d7 | 101 | signal (SIGALRM, quit); |
f6ea5628 DJ |
102 | alarm (5); |
103 | /* Check for quadratic performance. */ | |
104 | if (haystack && needle) | |
105 | { | |
f434ba03 PA |
106 | memset (haystack, 'A', 2 * m); |
107 | haystack[2 * m] = 'B'; | |
108 | memset (needle, 'A', m); | |
109 | needle[m] = 'B'; | |
770d76d7 PA |
110 | if (!memmem (haystack, 2 * m + 1, needle, m + 1)) |
111 | result |= 1; | |
f6ea5628 | 112 | } |
770d76d7 PA |
113 | return result; |
114 | ]])], | |
115 | [gl_cv_func_memmem_works_fast=yes], [gl_cv_func_memmem_works_fast=no], | |
116 | [dnl Only glibc >= 2.9 and cygwin > 1.7.0 are known to have a | |
f434ba03 PA |
117 | dnl memmem that works in linear time. |
118 | AC_EGREP_CPP([Lucky user], | |
119 | [ | |
120 | #include <features.h> | |
121 | #ifdef __GNU_LIBRARY__ | |
770d76d7 PA |
122 | #if ((__GLIBC__ == 2 && __GLIBC_MINOR__ >= 9) || (__GLIBC__ > 2)) \ |
123 | && !defined __UCLIBC__ | |
f434ba03 PA |
124 | Lucky user |
125 | #endif | |
126 | #endif | |
127 | #ifdef __CYGWIN__ | |
128 | #include <cygwin/version.h> | |
770d76d7 | 129 | #if CYGWIN_VERSION_DLL_COMBINED > CYGWIN_VERSION_DLL_MAKE_COMBINED (1007, 0) |
f434ba03 PA |
130 | Lucky user |
131 | #endif | |
132 | #endif | |
133 | ], | |
770d76d7 PA |
134 | [gl_cv_func_memmem_works_fast=yes], |
135 | [gl_cv_func_memmem_works_fast="guessing no"]) | |
f434ba03 PA |
136 | ]) |
137 | ]) | |
770d76d7 | 138 | if test "$gl_cv_func_memmem_works_fast" != yes; then |
f6ea5628 | 139 | REPLACE_MEMMEM=1 |
f6ea5628 DJ |
140 | fi |
141 | fi | |
142 | ]) # gl_FUNC_MEMMEM | |
143 | ||
144 | # Prerequisites of lib/memmem.c. | |
145 | AC_DEFUN([gl_PREREQ_MEMMEM], [:]) |