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| 1 # strstr.m4 serial 16 |
| 2 dnl Copyright (C) 2008-2012 Free Software Foundation, Inc. |
| 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([[ |
| 70 #include <signal.h> /* for signal */ |
| 71 #include <string.h> /* for strstr */ |
| 72 #include <stdlib.h> /* for malloc */ |
| 73 #include <unistd.h> /* for alarm */ |
| 74 static void quit (int sig) { exit (sig + 128); } |
| 75 ]], [[ |
| 76 int result = 0; |
| 77 size_t m = 1000000; |
| 78 char *haystack = (char *) malloc (2 * m + 2); |
| 79 char *needle = (char *) malloc (m + 2); |
| 80 /* Failure to compile this test due to missing alarm is okay, |
| 81 since all such platforms (mingw) also have quadratic strstr. */ |
| 82 signal (SIGALRM, quit); |
| 83 alarm (5); |
| 84 /* Check for quadratic performance. */ |
| 85 if (haystack && needle) |
| 86 { |
| 87 memset (haystack, 'A', 2 * m); |
| 88 haystack[2 * m] = 'B'; |
| 89 haystack[2 * m + 1] = 0; |
| 90 memset (needle, 'A', m); |
| 91 needle[m] = 'B'; |
| 92 needle[m + 1] = 0; |
| 93 if (!strstr (haystack, needle)) |
| 94 result |= 1; |
| 95 } |
| 96 return result; |
| 97 ]])], |
| 98 [gl_cv_func_strstr_linear=yes], [gl_cv_func_strstr_linear=no], |
| 99 [dnl Only glibc > 2.12 on processors without SSE 4.2 instructions and |
| 100 dnl cygwin > 1.7.7 are known to have a bug-free strstr that works in |
| 101 dnl linear time. |
| 102 AC_EGREP_CPP([Lucky user], |
| 103 [ |
| 104 #include <features.h> |
| 105 #ifdef __GNU_LIBRARY__ |
| 106 #if ((__GLIBC__ == 2 && __GLIBC_MINOR__ > 12) || (__GLIBC__ > 2)) \ |
| 107 && !(defined __i386__ || defined __x86_64__) \ |
| 108 && !defined __UCLIBC__ |
| 109 Lucky user |
| 110 #endif |
| 111 #endif |
| 112 #ifdef __CYGWIN__ |
| 113 #include <cygwin/version.h> |
| 114 #if CYGWIN_VERSION_DLL_COMBINED > CYGWIN_VERSION_DLL_MAKE_COMBINED (1007, 7) |
| 115 Lucky user |
| 116 #endif |
| 117 #endif |
| 118 ], |
| 119 [gl_cv_func_strstr_linear="guessing yes"], |
| 120 [gl_cv_func_strstr_linear="guessing no"]) |
| 121 ]) |
| 122 ]) |
| 123 case "$gl_cv_func_strstr_linear" in |
| 124 *yes) ;; |
| 125 *) |
| 126 REPLACE_STRSTR=1 |
| 127 ;; |
| 128 esac |
| 129 fi |
| 130 ]) # gl_FUNC_STRSTR |
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