X-Git-Url: http://erislabs.net/gitweb/?a=blobdiff_plain;ds=sidebyside;f=m4%2Fmemmem.m4;h=c6506ee5c8138e81d47ec6a603973211250eb3be;hb=aeca137662d6d2a7eaade72667ace75322872254;hp=7f3aa3c70f0f65c8b553513743757203c700b205;hpb=1e678e693dbf8abbc35d8d770ebefeb326cf76a3;p=gnulib.git

diff --git a/m4/memmem.m4 b/m4/memmem.m4
index 7f3aa3c70..c6506ee5c 100644
--- a/m4/memmem.m4
+++ b/m4/memmem.m4
@@ -1,5 +1,6 @@
-# memmem.m4 serial 9
-dnl Copyright (C) 2002, 2003, 2004, 2007, 2008 Free Software Foundation, Inc.
+# memmem.m4 serial 14
+dnl Copyright (C) 2002, 2003, 2004, 2007, 2008, 2009, 2010 Free Software
+dnl 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.
@@ -11,8 +12,8 @@ AC_DEFUN([gl_FUNC_MEMMEM_SIMPLE],
   AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])
 
   AC_REQUIRE([gl_HEADER_STRING_H_DEFAULTS])
-  AC_REPLACE_FUNCS(memmem)
-  AC_CHECK_DECLS_ONCE(memmem)
+  AC_REPLACE_FUNCS([memmem])
+  AC_CHECK_DECLS_ONCE([memmem])
   if test $ac_cv_have_decl_memmem = no; then
     HAVE_DECL_MEMMEM=0
   fi
@@ -26,32 +27,52 @@ AC_DEFUN([gl_FUNC_MEMMEM],
   if test $ac_cv_have_decl_memmem = yes; then
     AC_CACHE_CHECK([whether memmem works in linear time],
       [gl_cv_func_memmem_works],
-      [AC_RUN_IFELSE([AC_LANG_PROGRAM([
+      [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;
+]], [[size_t m = 1000000;
     char *haystack = (char *) malloc (2 * m + 1);
     char *needle = (char *) malloc (m + 1);
     void *result = 0;
     /* Failure to compile this test due to missing alarm is okay,
        since all such platforms (mingw) also lack memmem.  */
+    signal (SIGALRM, SIG_DFL);
     alarm (5);
     /* Check for quadratic performance.  */
     if (haystack && needle)
       {
-	memset (haystack, 'A', 2 * m);
-	haystack[2 * m] = 'B';
-	memset (needle, 'A', m);
-	needle[m] = 'B';
-	result = memmem (haystack, 2 * m + 1, needle, m + 1);
+        memset (haystack, 'A', 2 * m);
+        haystack[2 * m] = 'B';
+        memset (needle, 'A', m);
+        needle[m] = 'B';
+        result = memmem (haystack, 2 * m + 1, needle, m + 1);
       }
     /* Check for empty needle behavior.  */
     return !result || !memmem ("a", 1, 0, 0);]])],
-	[gl_cv_func_memmem_works=yes], [gl_cv_func_memmem_works=no],
-	[dnl pessimistically assume the worst, since even glibc 2.6.1
-	 dnl has quadratic complexity in its memmem
-	 gl_cv_func_memmem_works="guessing no"])])
+        [gl_cv_func_memmem_works=yes], [gl_cv_func_memmem_works=no],
+        [dnl Only glibc >= 2.9 and cygwin >= 1.7.0 are known to have a
+         dnl memmem 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_memmem_works=yes],
+           [gl_cv_func_memmem_works="guessing no"])
+        ])
+      ])
     if test "$gl_cv_func_memmem_works" != yes; then
       REPLACE_MEMMEM=1
       AC_LIBOBJ([memmem])