[Emacs-diffs] /srv/bzr/emacs/trunk r107074: Handle overflow when computing char display width (Bug#9496).

[Paul Eggert]

------------------------------------------------------------
revno: 107074
committer: Paul Eggert <address@hidden>
branch nick: trunk
timestamp: Fri 2012-02-03 11:24:22 -0800
message:
  Handle overflow when computing char display width (Bug#9496).
  
  * character.c (char_width): Return EMACS_INT, not int.
  (char_width, c_string_width): Check for overflow when
  computing the width; this is possible now that individual
  characters can have unbounded width.  Problem introduced
  by merge from Emacs 23 on 2012-01-19.
modified:
  src/ChangeLog
  src/character.c

=== modified file 'src/ChangeLog'
--- a/src/ChangeLog     2012-02-02 12:47:09 +0000
+++ b/src/ChangeLog     2012-02-03 19:24:22 +0000
@@ -1,3 +1,12 @@
+2012-02-03  Paul Eggert  <address@hidden>
+
+       Handle overflow when computing char display width (Bug#9496).
+       * character.c (char_width): Return EMACS_INT, not int.
+       (char_width, c_string_width): Check for overflow when
+       computing the width; this is possible now that individual
+       characters can have unbounded width.  Problem introduced
+       by merge from Emacs 23 on 2012-01-19.
+
 2012-02-02  Michael Albinus  <address@hidden>
 
        * dbusbind.c (Fdbus_register_method): Mention the return value

=== modified file 'src/character.c'
--- a/src/character.c   2012-01-19 07:21:25 +0000
+++ b/src/character.c   2012-02-03 19:24:22 +0000
@@ -311,10 +311,10 @@
 
 /* Return width (columns) of C considering the buffer display table DP. */
 
-static int
+static EMACS_INT
 char_width (int c, struct Lisp_Char_Table *dp)
 {
-  int width = CHAR_WIDTH (c);
+  EMACS_INT width = CHAR_WIDTH (c);
 
   if (dp)
     {
@@ -326,7 +326,12 @@
          {
            ch = AREF (disp, i);
            if (CHARACTERP (ch))
-             width += CHAR_WIDTH (XFASTINT (ch));
+             {
+               int w = CHAR_WIDTH (XFASTINT (ch));
+               if (INT_ADD_OVERFLOW (width, w))
+                 string_overflow ();
+               width += w;
+             }
          }
     }
   return width;
@@ -340,7 +345,8 @@
 usage: (char-width CHAR)  */)
   (Lisp_Object ch)
 {
-  int c, width;
+  int c;
+  EMACS_INT width;
 
   CHECK_CHARACTER (ch);
   c = XINT (ch);
@@ -367,10 +373,14 @@
     {
       int bytes;
       int c = STRING_CHAR_AND_LENGTH (str + i_byte, bytes);
-      int thiswidth = char_width (c, dp);
+      EMACS_INT thiswidth = char_width (c, dp);
 
-      if (precision > 0
-         && (width + thiswidth > precision))
+      if (precision <= 0)
+       {
+         if (INT_ADD_OVERFLOW (width, thiswidth))
+           string_overflow ();
+       }
+      else if (precision - width < thiswidth)
        {
          *nchars = i;
          *nbytes = i_byte;