Take over the maintenance of some older macros from Autoconf.

[gnulib.git] / m4 / memcmp.m4

diff --git a/m4/memcmp.m4 b/m4/memcmp.m4
index c0e9265..a15e9b7 100644 (file)
--- a/m4/memcmp.m4
+++ b/m4/memcmp.m4
@@ -1,4 +1,4 @@
-# memcmp.m4 serial 14
+# memcmp.m4 serial 15
 dnl Copyright (C) 2002-2004, 2007-2010 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -27,5 +27,42 @@ AC_DEFUN([gl_FUNC_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+# Redefine AC_FUNC_MEMCMP, because it is no longer maintained in Autoconf.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], [:])