Fix a crash in stand-alone Info due to bad indexing of a string

[Eli Zaretskii]

The stand-alone Info reader crashed on me today when I did
index-search.  Debugging that, I found a faulty logic in indices.c,
which caused us to write outside of a string's bounds when we up-case
or down-case a partial match found by index-search.  The result was
that the following call to 'free' crashed.

Here's the patch to fix this:

2013-03-20  Eli Zaretskii  <address@hidden>

        * info/indices.c (info_next_index_match): Fix computation of
        'partial', as setting it to 1 causes crashes because upcasing or
        downcasing the match writes outside of match[] string bounds.


--- indices.c~  2013-02-23 02:11:25.000000000 +0200
+++ indices.c   2013-03-20 19:39:51.850527800 +0200
@@ -417,14 +417,13 @@
         matches. */
       for (i = index_offset + dir; (i > -1) && (index_index[i]); i += dir)
         if (!index_entry_matches (index_index[i], index_search, search_len) &&
-           string_in_line (index_search, index_index[i]->label) != -1)
-         {
-           partial = 1;
-           break;
-         }
+           (partial =
+            string_in_line (index_search, index_index[i]->label)) != -1)
+         break;
     }
-  index_partial = partial;
-  
+  if (partial <= 0)
+    index_partial = 0;
+
   /* If that failed, print an error. */
   if ((i < 0) || (!index_index[i]))
     {
@@ -459,7 +458,7 @@
        string matched. */
     match = xstrdup (index_index[i]->label);
 
-    if (partial && show_index_match)
+    if (partial > 0 && show_index_match)
       {
         int k, ls, start, upper;