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49e4877c PA |
1 | # strstr.m4 serial 17 |
2 | dnl Copyright (C) 2008-2016 Free Software Foundation, Inc. | |
63ce7108 TT |
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 | ||
7 | dnl Check that strstr works. | |
8 | AC_DEFUN([gl_FUNC_STRSTR_SIMPLE], | |
9 | [ | |
10 | AC_REQUIRE([gl_HEADER_STRING_H_DEFAULTS]) | |
11 | AC_REQUIRE([gl_FUNC_MEMCHR]) | |
12 | if test "$gl_cv_func_memchr_works" != yes; then | |
13 | REPLACE_STRSTR=1 | |
14 | else | |
15 | dnl Detect http://sourceware.org/bugzilla/show_bug.cgi?id=12092. | |
16 | AC_CACHE_CHECK([whether strstr works], | |
17 | [gl_cv_func_strstr_works_always], | |
18 | [AC_RUN_IFELSE([AC_LANG_PROGRAM([[ | |
19 | #include <string.h> /* for strstr */ | |
20 | #define P "_EF_BF_BD" | |
21 | #define HAYSTACK "F_BD_CE_BD" P P P P "_C3_88_20" P P P "_C3_A7_20" P | |
22 | #define NEEDLE P P P P P | |
23 | ]], [[return !!strstr (HAYSTACK, NEEDLE); | |
24 | ]])], | |
25 | [gl_cv_func_strstr_works_always=yes], | |
26 | [gl_cv_func_strstr_works_always=no], | |
27 | [dnl glibc 2.12 and cygwin 1.7.7 have a known bug. uClibc is not | |
28 | dnl affected, since it uses different source code for strstr than | |
29 | dnl glibc. | |
30 | dnl Assume that it works on all other platforms, even if it is not | |
31 | dnl linear. | |
32 | AC_EGREP_CPP([Lucky user], | |
33 | [ | |
34 | #ifdef __GNU_LIBRARY__ | |
35 | #include <features.h> | |
36 | #if ((__GLIBC__ == 2 && __GLIBC_MINOR__ > 12) || (__GLIBC__ > 2)) \ | |
37 | || defined __UCLIBC__ | |
38 | Lucky user | |
39 | #endif | |
40 | #elif defined __CYGWIN__ | |
41 | #include <cygwin/version.h> | |
42 | #if CYGWIN_VERSION_DLL_COMBINED > CYGWIN_VERSION_DLL_MAKE_COMBINED (1007, 7) | |
43 | Lucky user | |
44 | #endif | |
45 | #else | |
46 | Lucky user | |
47 | #endif | |
48 | ], | |
49 | [gl_cv_func_strstr_works_always="guessing yes"], | |
50 | [gl_cv_func_strstr_works_always="guessing no"]) | |
51 | ]) | |
52 | ]) | |
53 | case "$gl_cv_func_strstr_works_always" in | |
54 | *yes) ;; | |
55 | *) | |
56 | REPLACE_STRSTR=1 | |
57 | ;; | |
58 | esac | |
59 | fi | |
60 | ]) # gl_FUNC_STRSTR_SIMPLE | |
61 | ||
62 | dnl Additionally, check that strstr is efficient. | |
63 | AC_DEFUN([gl_FUNC_STRSTR], | |
64 | [ | |
65 | AC_REQUIRE([gl_FUNC_STRSTR_SIMPLE]) | |
66 | if test $REPLACE_STRSTR = 0; then | |
67 | AC_CACHE_CHECK([whether strstr works in linear time], | |
68 | [gl_cv_func_strstr_linear], | |
69 | [AC_RUN_IFELSE([AC_LANG_PROGRAM([[ | |
49e4877c PA |
70 | #ifdef __MVS__ |
71 | /* z/OS does not deliver signals while strstr() is running (thanks to | |
72 | restrictions on its LE runtime), which prevents us from limiting the | |
73 | running time of this test. */ | |
74 | # error "This test does not work properly on z/OS" | |
75 | #endif | |
63ce7108 TT |
76 | #include <signal.h> /* for signal */ |
77 | #include <string.h> /* for strstr */ | |
78 | #include <stdlib.h> /* for malloc */ | |
79 | #include <unistd.h> /* for alarm */ | |
49e4877c | 80 | static void quit (int sig) { _exit (sig + 128); } |
63ce7108 TT |
81 | ]], [[ |
82 | int result = 0; | |
83 | size_t m = 1000000; | |
84 | char *haystack = (char *) malloc (2 * m + 2); | |
85 | char *needle = (char *) malloc (m + 2); | |
86 | /* Failure to compile this test due to missing alarm is okay, | |
87 | since all such platforms (mingw) also have quadratic strstr. */ | |
88 | signal (SIGALRM, quit); | |
89 | alarm (5); | |
90 | /* Check for quadratic performance. */ | |
91 | if (haystack && needle) | |
92 | { | |
93 | memset (haystack, 'A', 2 * m); | |
94 | haystack[2 * m] = 'B'; | |
95 | haystack[2 * m + 1] = 0; | |
96 | memset (needle, 'A', m); | |
97 | needle[m] = 'B'; | |
98 | needle[m + 1] = 0; | |
99 | if (!strstr (haystack, needle)) | |
100 | result |= 1; | |
101 | } | |
102 | return result; | |
103 | ]])], | |
104 | [gl_cv_func_strstr_linear=yes], [gl_cv_func_strstr_linear=no], | |
105 | [dnl Only glibc > 2.12 on processors without SSE 4.2 instructions and | |
106 | dnl cygwin > 1.7.7 are known to have a bug-free strstr that works in | |
107 | dnl linear time. | |
108 | AC_EGREP_CPP([Lucky user], | |
109 | [ | |
110 | #include <features.h> | |
111 | #ifdef __GNU_LIBRARY__ | |
112 | #if ((__GLIBC__ == 2 && __GLIBC_MINOR__ > 12) || (__GLIBC__ > 2)) \ | |
113 | && !(defined __i386__ || defined __x86_64__) \ | |
114 | && !defined __UCLIBC__ | |
115 | Lucky user | |
116 | #endif | |
117 | #endif | |
118 | #ifdef __CYGWIN__ | |
119 | #include <cygwin/version.h> | |
120 | #if CYGWIN_VERSION_DLL_COMBINED > CYGWIN_VERSION_DLL_MAKE_COMBINED (1007, 7) | |
121 | Lucky user | |
122 | #endif | |
123 | #endif | |
124 | ], | |
125 | [gl_cv_func_strstr_linear="guessing yes"], | |
126 | [gl_cv_func_strstr_linear="guessing no"]) | |
127 | ]) | |
128 | ]) | |
129 | case "$gl_cv_func_strstr_linear" in | |
130 | *yes) ;; | |
131 | *) | |
132 | REPLACE_STRSTR=1 | |
133 | ;; | |
134 | esac | |
135 | fi | |
136 | ]) # gl_FUNC_STRSTR |