Merge commit 'stable/20110609'

[gnulib.git] / m4 / memcmp.m4

diff --git a/m4/memcmp.m4 b/m4/memcmp.m4
index a6b6d54..db1146b 100644 (file)
--- a/m4/memcmp.m4
+++ b/m4/memcmp.m4
@@ -1,9 +1,68 @@
-#serial 6
+# memcmp.m4 serial 15
+dnl Copyright (C) 2002-2004, 2007-2011 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.
 
-AC_DEFUN(jm_FUNC_MEMCMP,
-[AC_REQUIRE([AC_FUNC_MEMCMP])dnl
- if test $ac_cv_func_memcmp_working = no; then
-   AC_DEFINE_UNQUOTED(memcmp, rpl_memcmp,
-     [Define to rpl_memcmp if the replacement function should be used.])
- fi
+AC_DEFUN([gl_FUNC_MEMCMP],
+[
+  if test $cross_compiling != no; then
+    # AC_FUNC_MEMCMP as of 2.62 defaults to 'no' when cross compiling.
+    # We default to yes if memcmp appears to exist, which works
+    # better for MinGW.
+    AC_CACHE_CHECK([whether cross-compiling target has memcmp],
+                   [ac_cv_func_memcmp_working],
+                   [AC_LINK_IFELSE([
+                        AC_LANG_PROGRAM([[#include <string.h>
+                                ]], [[int ret = memcmp ("foo", "bar", 0);]])],
+                        [ac_cv_func_memcmp_working=yes],
+                        [ac_cv_func_memcmp_working=no])])
+  fi
+  AC_FUNC_MEMCMP
+  dnl Note: AC_FUNC_MEMCMP does AC_LIBOBJ([memcmp]).
+  if test $ac_cv_func_memcmp_working = no; then
+    AC_DEFINE([memcmp], [rpl_memcmp],
+      [Define to rpl_memcmp if the replacement function should be used.])
+    gl_PREREQ_MEMCMP
+  fi
 ])
+
+# Redefine AC_FUNC_MEMCMP, because it is no longer maintained in Autoconf.
+AC_DEFUN([AC_FUNC_MEMCMP],
+[
+  AC_CACHE_CHECK([for working memcmp], [ac_cv_func_memcmp_working],
+    [AC_RUN_IFELSE(
+       [AC_LANG_PROGRAM(
+          [AC_INCLUDES_DEFAULT],
+          [[/* Some versions of memcmp are not 8-bit clean.  */
+            char c0 = '\100', c1 = '\200', c2 = '\201';
+            if (memcmp(&c0, &c2, 1) >= 0 || memcmp(&c1, &c2, 1) >= 0)
+              return 1;
+            /* The Next x86 OpenStep bug shows up only when comparing 16 bytes
+               or more and with at least one buffer not starting on a 4-byte
+               boundary.  William Lewis provided this test program.   */
+            {
+              char foo[21];
+              char bar[21];
+              int i;
+              for (i = 0; i < 4; i++)
+                {
+                  char *a = foo + i;
+                  char *b = bar + i;
+                  strcpy (a, "--------01111111");
+                  strcpy (b, "--------10000000");
+                  if (memcmp (a, b, 16) >= 0)
+                    return 1;
+                }
+              return 0;
+            }
+          ]])],
+       [ac_cv_func_memcmp_working=yes],
+       [ac_cv_func_memcmp_working=no],
+       [ac_cv_func_memcmp_working=no])])
+  test $ac_cv_func_memcmp_working = no &&
+    AC_LIBOBJ([memcmp])
+])
+
+# Prerequisites of lib/memcmp.c.
+AC_DEFUN([gl_PREREQ_MEMCMP], [:])