* charset.c (Fdefine_charset_internal): Check for integer overflow.

Add a FIXME comment about memory leaks.
(syms_of_charset): Don't assume xmalloc returns.

diff --git a/src/ChangeLog b/src/ChangeLog
index 54ce0c8..4a9e03d 100644 (file)
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,5 +1,9 @@
 2011-07-19  Paul Eggert  <eggert@cs.ucla.edu>
 
+       * charset.c (Fdefine_charset_internal): Check for integer overflow.
+       Add a FIXME comment about memory leaks.
+       (syms_of_charset): Don't assume xmalloc returns.
+
        Don't assume that stated character widths fit in int.
        * character.c (Fchar_width, c_string_width, lisp_string_width):
        * character.h (CHAR_WIDTH):

diff --git a/src/charset.c b/src/charset.c
index e2bfcd0..852aeb1 100644 (file)
--- a/src/charset.c
+++ b/src/charset.c
@@ -1150,13 +1150,28 @@ usage: (define-charset-internal ...)  */)
                                     hash_code);
       if (charset_table_used == charset_table_size)
        {
-         struct charset *new_table
+         struct charset *new_table;
+         /* Ensure that charset IDs fit into 'int' as well as into the
+            restriction imposed by fixnums, ptrdiff_t, and size_t.
+            Although the 'int' restriction could be removed, too much other
+            code would need altering; for example, the IDs are stuffed into
+            struct coding_system.charbuf[i] entries, which are 'int'.  */
+         int charset_table_size_max =
+           min (min (INT_MAX, MOST_POSITIVE_FIXNUM),
+                min (PTRDIFF_MAX, SIZE_MAX) / sizeof (struct charset));
+         if (charset_table_size_max - 16 < charset_table_size)
+           memory_full (SIZE_MAX);
+         new_table
            = (struct charset *) xmalloc (sizeof (struct charset)
                                          * (charset_table_size + 16));
          memcpy (new_table, charset_table,
                  sizeof (struct charset) * charset_table_size);
          charset_table_size += 16;
          charset_table = new_table;
+         /* FIXME: Doesn't this leak memory?  The old charset_table
+            becomes unreachable.  If the memory leak is intentional,
+            a comment should be added to explain this.  If not, the
+            old charset_table should be freed, using xfree.  */
        }
       id = charset_table_used++;
       new_definition_p = 1;
@@ -2347,9 +2362,8 @@ syms_of_charset (void)
     Vcharset_hash_table = Fmake_hash_table (2, args);
   }
 
+  charset_table = (struct charset *) xmalloc (sizeof (struct charset) * 128);
   charset_table_size = 128;
-  charset_table = ((struct charset *)
-                  xmalloc (sizeof (struct charset) * charset_table_size));
   charset_table_used = 0;
 
   defsubr (&Scharsetp);