Mercurial > gnulib
view m4/strstr.m4 @ 10189:2304e9103317
Work around environments that (stupidly) ignore SIGALRM.
* m4/strstr.m4 (gl_FUNC_STRSTR): Reset SIGALRM to default handling
before using alarm().
* m4/strcasestr.m4 (gl_FUNC_STRCASESTR): Likewise.
* m4/memmem.m4 (gl_FUNC_MEMMEM): Likewise.
Reported by Ian Beckwith <ianb@erislabs.net>.
Signed-off-by: Eric Blake <ebb9@byu.net>
author | Eric Blake <ebb9@byu.net> |
---|---|
date | Mon, 09 Jun 2008 16:21:34 -0600 |
parents | 44e8848f6ce8 |
children | 59047bad770e |
line wrap: on
line source
# strstr.m4 serial 5 dnl Copyright (C) 2008 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 is efficient. AC_DEFUN([gl_FUNC_STRSTR], [ AC_REQUIRE([gl_HEADER_STRING_H_DEFAULTS]) 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 memmem */ #include <stdlib.h> /* for malloc */ #include <unistd.h> /* for alarm */ ]], [[size_t m = 1000000; char *haystack = (char *) malloc (2 * m + 2); char *needle = (char *) malloc (m + 2); void *result = 0; /* Failure to compile this test due to missing alarm is okay, since all such platforms (mingw) also have quadratic strstr. */ signal (SIGALRM, SIG_DFL); 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; result = strstr (haystack, needle); } return !result;]])], [gl_cv_func_strstr_linear=yes], [gl_cv_func_strstr_linear=no], [dnl Only glibc >= 2.9 and cygwin >= 1.7.0 are known to have a dnl strstr that works in linear time. AC_EGREP_CPP([Lucky user], [ #include <features.h> #ifdef __GNU_LIBRARY__ #if (__GLIBC__ == 2 && __GLIBC_MINOR__ >= 9) || (__GLIBC__ > 2) Lucky user #endif #endif #ifdef __CYGWIN__ #include <cygwin/version.h> #if CYGWIN_VERSION_DLL_MAJOR >= 1007 Lucky user #endif #endif ], [gl_cv_func_strstr_linear=yes], [gl_cv_func_strstr_linear="guessing no"]) ]) ]) if test "$gl_cv_func_strstr_linear" != yes; then REPLACE_STRSTR=1 AC_LIBOBJ([strstr]) fi ]) # gl_FUNC_STRSTR