Prefer ptrdiff_t to int and avoid integer overflows.

* fileio.c (make_temp_name):
* font.c (font_parse_family_registry): Avoid integer
overflow on string size calculation.
* data.c (Faset): Likewise for byte index.

src/ChangeLog

@@ -9,6 +9,12 @@
 	(apply_lambda): Likewise.  Get current specpdl level as 3rd arg.
 	(do_debug_on_call): Get current specpdl level as 2nd arg.
 
+	Prefer ptrdiff_t to int and avoid integer overflows.
+	* fileio.c (make_temp_name):
+	* font.c (font_parse_family_registry): Avoid integer
+	overflow on string size calculation.
+	* data.c (Faset): Likewise for byte index.
+
 2014-09-15  Eli Zaretskii  <eliz@gnu.org>
 
 	Fix display of R2L lines in partial-width windows.

src/data.c

@@ -2248,7 +2248,7 @@ bool-vector.  IDX starts at 0.  */)
 	{
 	  if (! SINGLE_BYTE_CHAR_P (c))
 	    {
-	      int i;
+	      ptrdiff_t i;
 
 	      for (i = SBYTES (array) - 1; i >= 0; i--)
 		if (SREF (array, i) >= 0x80)

src/fileio.c

@@ -733,7 +733,7 @@ Lisp_Object
 make_temp_name (Lisp_Object prefix, bool base64_p)
 {
   Lisp_Object val, encoded_prefix;
-  int len;
+  ptrdiff_t len;
   printmax_t pid;
   char *p, *data;
   char pidbuf[INT_BUFSIZE_BOUND (printmax_t)];

src/font.c

@@ -1724,7 +1724,7 @@ font_parse_name (char *name, ptrdiff_t namelen, Lisp_Object font)
 void
 font_parse_family_registry (Lisp_Object family, Lisp_Object registry, Lisp_Object font_spec)
 {
-  int len;
+  ptrdiff_t len;
   char *p0, *p1;
 
   if (! NILP (family)