Avoid expanding two macros in the wrong order.

[gnulib.git] / lib / memcoll.c

diff --git a/lib/memcoll.c b/lib/memcoll.c
index 09f9f2d..e08ffa5 100644 (file)
--- a/lib/memcoll.c
+++ b/lib/memcoll.c
@@ -1,10 +1,12 @@
 /* Locale-specific memory comparison.
-   Copyright 1999 Free Software Foundation, Inc.
 
-   This program is free software; you can redistribute it and/or modify
+   Copyright (C) 1999, 2002-2004, 2006, 2009-2010 Free Software Foundation,
+   Inc.
+
+   This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
-   the Free Software Foundation; either version 2, or (at your option)
-   any later version.
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
 
    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ -12,60 +14,83 @@
    GNU General Public License for more details.
 
    You should have received a copy of the GNU General Public License
-   along with this program; if not, write to the Free Software Foundation,
-   Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
 
 /* Contributed by Paul Eggert <eggert@twinsun.com>.  */
 
-#if HAVE_CONFIG_H
-# include <config.h>
-#endif
+#include <config.h>
 
-#if HAVE_STRING_H
-# include <string.h>
-#endif
+#include "memcoll.h"
+
+#include <errno.h>
+#include <string.h>
 
 /* Compare S1 (with length S1LEN) and S2 (with length S2LEN) according
    to the LC_COLLATE locale.  S1 and S2 do not overlap, and are not
-   adjacent.  Temporarily modify the bytes after S1 and S2, but
-   restore their original contents before returning.  */
+   adjacent.  Perhaps temporarily modify the bytes after S1 and S2,
+   but restore their original contents before returning.  Set errno to an
+   error number if there is an error, and to zero otherwise.  */
 int
 memcoll (char *s1, size_t s1len, char *s2, size_t s2len)
 {
   int diff;
-  char n1 = s1[s1len];
-  char n2 = s2[s2len];
 
-  s1[s1len++] = '\0';
-  s2[s2len++] = '\0';
+#if HAVE_STRCOLL
 
-  while (! (diff = strcoll (s1, s2)))
+  /* strcoll is slow on many platforms, so check for the common case
+     where the arguments are bytewise equal.  Otherwise, walk through
+     the buffers using strcoll on each substring.  */
+
+  if (s1len == s2len && memcmp (s1, s2, s1len) == 0)
+    {
+      errno = 0;
+      diff = 0;
+    }
+  else
     {
-      /* strcoll found no difference, but perhaps it was fooled by NUL
-        characters in the data.  Work around this problem by advancing
-        past the NUL chars.  */
-      size_t size1 = strlen (s1) + 1;
-      size_t size2 = strlen (s2) + 1;
-      s1 += size1;
-      s2 += size2;
-      s1len -= size1;
-      s2len -= size2;
-
-      if (s1len == 0)
-       {
-         if (s2len != 0)
-           diff = -1;
-         break;
-       }
-      else if (s2len == 0)
-       {
-         diff = 1;
-         break;
-       }
+      char n1 = s1[s1len];
+      char n2 = s2[s2len];
+
+      s1[s1len++] = '\0';
+      s2[s2len++] = '\0';
+
+      while (! (errno = 0, (diff = strcoll (s1, s2)) || errno))
+        {
+          /* strcoll found no difference, but perhaps it was fooled by NUL
+             characters in the data.  Work around this problem by advancing
+             past the NUL chars.  */
+          size_t size1 = strlen (s1) + 1;
+          size_t size2 = strlen (s2) + 1;
+          s1 += size1;
+          s2 += size2;
+          s1len -= size1;
+          s2len -= size2;
+
+          if (s1len == 0)
+            {
+              if (s2len != 0)
+                diff = -1;
+              break;
+            }
+          else if (s2len == 0)
+            {
+              diff = 1;
+              break;
+            }
+        }
+
+      s1[s1len - 1] = n1;
+      s2[s2len - 1] = n2;
     }
 
-  s1[s1len - 1] = n1;
-  s2[s2len - 1] = n2;
+#else
+
+  diff = memcmp (s1, s2, s1len < s2len ? s1len : s2len);
+  if (! diff)
+    diff = s1len < s2len ? -1 : s1len != s2len;
+  errno = 0;
+
+#endif
 
   return diff;
 }