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Diffstat (limited to 'm4/strstr.m4')
| -rw-r--r-- | m4/strstr.m4 | 130 |
1 files changed, 130 insertions, 0 deletions
diff --git a/m4/strstr.m4 b/m4/strstr.m4 new file mode 100644 index 0000000..c486bdb --- /dev/null +++ b/m4/strstr.m4 @@ -0,0 +1,130 @@ +# strstr.m4 serial 16 +dnl Copyright (C) 2008-2013 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 strstr works. +AC_DEFUN([gl_FUNC_STRSTR_SIMPLE], +[ + AC_REQUIRE([gl_HEADER_STRING_H_DEFAULTS]) + AC_REQUIRE([gl_FUNC_MEMCHR]) + if test "$gl_cv_func_memchr_works" != yes; then + REPLACE_STRSTR=1 + else + dnl Detect http://sourceware.org/bugzilla/show_bug.cgi?id=12092. + AC_CACHE_CHECK([whether strstr works], + [gl_cv_func_strstr_works_always], + [AC_RUN_IFELSE([AC_LANG_PROGRAM([[ +#include <string.h> /* for strstr */ +#define P "_EF_BF_BD" +#define HAYSTACK "F_BD_CE_BD" P P P P "_C3_88_20" P P P "_C3_A7_20" P +#define NEEDLE P P P P P +]], [[return !!strstr (HAYSTACK, NEEDLE); + ]])], + [gl_cv_func_strstr_works_always=yes], + [gl_cv_func_strstr_works_always=no], + [dnl glibc 2.12 and cygwin 1.7.7 have a known bug. uClibc is not + dnl affected, since it uses different source code for strstr than + dnl glibc. + dnl Assume that it works on all other platforms, even if it is not + dnl linear. + AC_EGREP_CPP([Lucky user], + [ +#ifdef __GNU_LIBRARY__ + #include <features.h> + #if ((__GLIBC__ == 2 && __GLIBC_MINOR__ > 12) || (__GLIBC__ > 2)) \ + || defined __UCLIBC__ + Lucky user + #endif +#elif defined __CYGWIN__ + #include <cygwin/version.h> + #if CYGWIN_VERSION_DLL_COMBINED > CYGWIN_VERSION_DLL_MAKE_COMBINED (1007, 7) + Lucky user + #endif +#else + Lucky user +#endif + ], + [gl_cv_func_strstr_works_always="guessing yes"], + [gl_cv_func_strstr_works_always="guessing no"]) + ]) + ]) + case "$gl_cv_func_strstr_works_always" in + *yes) ;; + *) + REPLACE_STRSTR=1 + ;; + esac + fi +]) # gl_FUNC_STRSTR_SIMPLE + +dnl Additionally, check that strstr is efficient. +AC_DEFUN([gl_FUNC_STRSTR], +[ + AC_REQUIRE([gl_FUNC_STRSTR_SIMPLE]) + if test $REPLACE_STRSTR = 0; then + AC_CACHE_CHECK([whether strstr works in linear time], + [gl_cv_func_strstr_linear], + [AC_RUN_IFELSE([AC_LANG_PROGRAM([[ +#include <signal.h> /* for signal */ +#include <string.h> /* for strstr */ +#include <stdlib.h> /* for malloc */ +#include <unistd.h> /* for alarm */ +static void quit (int sig) { exit (sig + 128); } +]], [[ + int result = 0; + size_t m = 1000000; + char *haystack = (char *) malloc (2 * m + 2); + char *needle = (char *) malloc (m + 2); + /* Failure to compile this test due to missing alarm is okay, + since all such platforms (mingw) also have quadratic strstr. */ + signal (SIGALRM, quit); + alarm (5); + /* Check for quadratic performance. */ + if (haystack && needle) + { + memset (haystack, 'A', 2 * m); + haystack[2 * m] = 'B'; + haystack[2 * m + 1] = 0; + memset (needle, 'A', m); + needle[m] = 'B'; + needle[m + 1] = 0; + if (!strstr (haystack, needle)) + result |= 1; + } + return result; + ]])], + [gl_cv_func_strstr_linear=yes], [gl_cv_func_strstr_linear=no], + [dnl Only glibc > 2.12 on processors without SSE 4.2 instructions and + dnl cygwin > 1.7.7 are known to have a bug-free strstr that works in + dnl linear time. + AC_EGREP_CPP([Lucky user], + [ +#include <features.h> +#ifdef __GNU_LIBRARY__ + #if ((__GLIBC__ == 2 && __GLIBC_MINOR__ > 12) || (__GLIBC__ > 2)) \ + && !(defined __i386__ || defined __x86_64__) \ + && !defined __UCLIBC__ + Lucky user + #endif +#endif +#ifdef __CYGWIN__ + #include <cygwin/version.h> + #if CYGWIN_VERSION_DLL_COMBINED > CYGWIN_VERSION_DLL_MAKE_COMBINED (1007, 7) + Lucky user + #endif +#endif + ], + [gl_cv_func_strstr_linear="guessing yes"], + [gl_cv_func_strstr_linear="guessing no"]) + ]) + ]) + case "$gl_cv_func_strstr_linear" in + *yes) ;; + *) + REPLACE_STRSTR=1 + ;; + esac + fi +]) # gl_FUNC_STRSTR |