Integrate test to detect bug in memcmp from the

[gnulib.git] / m4 / memcmp.m4

diff --git a/m4/memcmp.m4 b/m4/memcmp.m4
index e76aeda..82b4b7c 100644 (file)
--- a/m4/memcmp.m4
+++ b/m4/memcmp.m4
@@ -1,4 +1,46 @@
-#serial 1
+#serial 2
+
+dnl A replacement for autoconf's AC_FUNC_MEMCMP that detects
+dnl the losing memcmp on some x86 Next systems.
+AC_DEFUN(jm_AC_FUNC_MEMCMP,
+[AC_CACHE_CHECK([for working memcmp], jm_cv_func_memcmp_working,
+[AC_TRY_RUN(
+changequote(<<, >>)dnl
+<<
+main()
+{
+  /* Some versions of memcmp are not 8-bit clean.  */
+  char c0 = 0x40, c1 = 0x80, c2 = 0x81;
+  if (memcmp(&c0, &c2, 1) >= 0 || memcmp(&c1, &c2, 1) >= 0)
+    exit (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)
+         exit (1);
+      }
+    exit (0);
+  }
+}
+>>,
+changequote([, ])dnl
+   jm_cv_func_memcmp_working=yes,
+   jm_cv_func_memcmp_working=no,
+   jm_cv_func_memcmp_working=no)])
+test $jm_cv_func_memcmp_working = no && LIBOBJS="$LIBOBJS memcmp.o"
+AC_SUBST(LIBOBJS)dnl
+])
 
 dnl If you use this macro in a package, you should
 dnl add the following two lines to acconfig.h:
@@ -6,8 +48,8 @@ dnl   /* Define to rpl_memcmp if the replacement function should be used.  */
 dnl   #undef memcmp
 dnl
 AC_DEFUN(jm_FUNC_MEMCMP,
-[AC_REQUIRE([AC_FUNC_MEMCMP])dnl
- if test $ac_cv_func_memcmp_clean = no; then
+[AC_REQUIRE([jm_AC_FUNC_MEMCMP])dnl
+ if test $jm_cv_func_memcmp_working = no; then
    AC_DEFINE_UNQUOTED(memcmp, rpl_memcmp)
  fi
 ])