1# strstr.m4 serial 24 2dnl Copyright (C) 2008-2022 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 strstr works. 8AC_DEFUN([gl_FUNC_STRSTR_SIMPLE], 9[ 10 AC_REQUIRE([gl_STRING_H_DEFAULTS]) 11 AC_REQUIRE([gl_FUNC_MEMCHR]) 12 if test $REPLACE_MEMCHR = 1; then 13 REPLACE_STRSTR=1 14 else 15 dnl Detect https://sourceware.org/bugzilla/show_bug.cgi?id=12092 16 dnl and https://sourceware.org/bugzilla/show_bug.cgi?id=23637. 17 AC_CACHE_CHECK([whether strstr works], 18 [gl_cv_func_strstr_works_always], 19 [AC_RUN_IFELSE( 20 [AC_LANG_PROGRAM([[ 21#include <string.h> /* for __GNU_LIBRARY__, strstr */ 22#ifdef __GNU_LIBRARY__ 23 #include <features.h> 24 #if __GLIBC__ == 2 && __GLIBC_MINOR__ == 28 25 Unlucky user 26 #endif 27#endif 28#define P "_EF_BF_BD" 29#define HAYSTACK "F_BD_CE_BD" P P P P "_C3_88_20" P P P "_C3_A7_20" P 30#define NEEDLE P P P P P 31]], 32 [[return !!strstr (HAYSTACK, NEEDLE); 33 ]])], 34 [gl_cv_func_strstr_works_always=yes], 35 [gl_cv_func_strstr_works_always=no], 36 [dnl glibc 2.12 and cygwin 1.7.7 have a known bug. uClibc is not 37 dnl affected, since it uses different source code for strstr than 38 dnl glibc. 39 dnl Assume that it works on all other platforms, even if it is not 40 dnl linear. 41 AC_EGREP_CPP([Lucky user], 42 [ 43#include <string.h> /* for __GNU_LIBRARY__ */ 44#ifdef __GNU_LIBRARY__ 45 #include <features.h> 46 #if ((__GLIBC__ == 2 && __GLIBC_MINOR__ > 12) || (__GLIBC__ > 2)) \ 47 || defined __UCLIBC__ 48 Lucky user 49 #endif 50#elif defined __CYGWIN__ 51 #include <cygwin/version.h> 52 #if CYGWIN_VERSION_DLL_COMBINED > CYGWIN_VERSION_DLL_MAKE_COMBINED (1007, 7) 53 Lucky user 54 #endif 55#else 56 Lucky user 57#endif 58 ], 59 [gl_cv_func_strstr_works_always="guessing yes"], 60 [gl_cv_func_strstr_works_always="$gl_cross_guess_normal"]) 61 ]) 62 ]) 63 case "$gl_cv_func_strstr_works_always" in 64 *yes) ;; 65 *) 66 REPLACE_STRSTR=1 67 ;; 68 esac 69 fi 70]) # gl_FUNC_STRSTR_SIMPLE 71 72dnl Additionally, check that strstr is efficient. 73AC_DEFUN([gl_FUNC_STRSTR], 74[ 75 AC_REQUIRE([gl_FUNC_STRSTR_SIMPLE]) 76 if test $REPLACE_STRSTR = 0; then 77 AC_CACHE_CHECK([whether strstr works in linear time], 78 [gl_cv_func_strstr_linear], 79 [AC_RUN_IFELSE([AC_LANG_PROGRAM([[ 80#ifdef __MVS__ 81/* z/OS does not deliver signals while strstr() is running (thanks to 82 restrictions on its LE runtime), which prevents us from limiting the 83 running time of this test. */ 84# error "This test does not work properly on z/OS" 85#endif 86#include <signal.h> /* for signal */ 87#include <string.h> /* for strstr */ 88#include <stdlib.h> /* for malloc */ 89#include <unistd.h> /* for alarm */ 90static void quit (int sig) { _exit (sig + 128); } 91]], [[ 92 int result = 0; 93 size_t m = 1000000; 94 char *haystack = (char *) malloc (2 * m + 2); 95 char *needle = (char *) malloc (m + 2); 96 /* Failure to compile this test due to missing alarm is okay, 97 since all such platforms (mingw) also have quadratic strstr. */ 98 signal (SIGALRM, quit); 99 alarm (5); 100 /* Check for quadratic performance. */ 101 if (haystack && needle) 102 { 103 memset (haystack, 'A', 2 * m); 104 haystack[2 * m] = 'B'; 105 haystack[2 * m + 1] = 0; 106 memset (needle, 'A', m); 107 needle[m] = 'B'; 108 needle[m + 1] = 0; 109 if (!strstr (haystack, needle)) 110 result |= 1; 111 } 112 /* Free allocated memory, in case some sanitizer is watching. */ 113 free (haystack); 114 free (needle); 115 return result; 116 ]])], 117 [gl_cv_func_strstr_linear=yes], [gl_cv_func_strstr_linear=no], 118 [dnl Only glibc > 2.12 on processors without SSE 4.2 instructions and 119 dnl cygwin > 1.7.7 are known to have a bug-free strstr that works in 120 dnl linear time. 121 AC_EGREP_CPP([Lucky user], 122 [ 123#include <features.h> 124#ifdef __GNU_LIBRARY__ 125 #if ((__GLIBC__ == 2 && __GLIBC_MINOR__ > 12) || (__GLIBC__ > 2)) \ 126 && !(defined __i386__ || defined __x86_64__) \ 127 && !defined __UCLIBC__ 128 Lucky user 129 #endif 130#endif 131#ifdef __CYGWIN__ 132 #include <cygwin/version.h> 133 #if CYGWIN_VERSION_DLL_COMBINED > CYGWIN_VERSION_DLL_MAKE_COMBINED (1007, 7) 134 Lucky user 135 #endif 136#endif 137 ], 138 [gl_cv_func_strstr_linear="guessing yes"], 139 [gl_cv_func_strstr_linear="$gl_cross_guess_normal"]) 140 ]) 141 ]) 142 case "$gl_cv_func_strstr_linear" in 143 *yes) ;; 144 *) 145 REPLACE_STRSTR=1 146 ;; 147 esac 148 fi 149]) # gl_FUNC_STRSTR 150