[glib] Bug 673047 - gunicollate is broken on OS X

[Michael Natterer <mitch src gnome org>]

commit ef8510be09a746dcbc8d470376688820b225c40f
Author: Michael Natterer <mitch gimp org>
Date:   Fri Nov 16 18:48:09 2012 +0100

    Bug 673047 - gunicollate is broken on OS X
    
    Apply slightly modified patch from Camillo Lugaresi which fixes
    gunicollate for OSX >= 10.6. It was totally hilariously broken
    for anyone on 10.6 and later, I dont know if it's now broken
    on 10.5, but better fix it for the vast majority of users.

 glib/gunicollate.c |   29 ++++++++++++++---------------
 1 files changed, 14 insertions(+), 15 deletions(-)
---
diff --git a/glib/gunicollate.c b/glib/gunicollate.c
index 3649786..050dd60 100644
--- a/glib/gunicollate.c
+++ b/glib/gunicollate.c
@@ -217,29 +217,28 @@ collate_key_to_string (UCCollationValue *key,
                        gsize             key_len)
 {
   gchar *result;
-  gsize result_len;
+  gsize result_len = 0;
+  const gsize start = 2 * sizeof (void *) / sizeof (UCCollationValue);
   gsize i;
 
-  /* Pretty smart algorithm here: ignore first eight bytes of the
-   * collation key. It doesn't produce results equivalent to
-   * UCCompareCollationKeys's, but the difference seems to be only
-   * that UCCompareCollationKeys in some cases produces 0 where our
-   * comparison gets -1 or 1. */
-
-  if (key_len * sizeof (UCCollationValue) <= 8)
+  /* The first codes should be skipped: the same string on the same
+   * system can get different values at runtime in those positions,
+   * and they do not sort correctly.  The exact size of the prefix
+   * depends on whether we are building 64 or 32 bit.
+   */
+  if (key_len <= start)
     return g_strdup ("");
 
-  result_len = 0;
-  for (i = 8; i < key_len * sizeof (UCCollationValue); i++)
-    /* there may be nul bytes, encode byteval+1 */
-    result_len += utf8_encode (NULL, *((guchar*)key + i) + 1);
+  for (i = start; i < key_len; i++)
+    result_len += utf8_encode (NULL, g_htonl (key[i] + 1));
 
   result = g_malloc (result_len + 1);
   result_len = 0;
-  for (i = 8; i < key_len * sizeof (UCCollationValue); i++)
-    result_len += utf8_encode (result + result_len, *((guchar*)key + i) + 1);
+  for (i = start; i < key_len; i++)
+    result_len += utf8_encode (result + result_len, g_htonl (key[i] + 1));
+
+  result[result_len] = '\0';
 
-  result[result_len] = 0;
   return result;
 }