* indent.c: Integer overflow fixes.

(position_indentation): Now takes ptrdiff_t, not int.
(Fvertical_motion): Don't wrap around LINES values that don't fit
in 'int'.  Instead, treat them as extreme values.  This is good
enough for windows, which can't have more than INT_MAX lines anyway.

2 files changed, 14 insertions, 6 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index 6113c2362ee..9c5ca280eba 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,11 @@
+2011-09-04  Paul Eggert  <eggert@cs.ucla.edu>
+
+        * indent.c: Integer overflow fixes.
+        (position_indentation): Now takes ptrdiff_t, not int.
+        (Fvertical_motion): Don't wrap around LINES values that don't fit
+        in 'int'.  Instead, treat them as extreme values.  This is good
+        enough for windows, which can't have more than INT_MAX lines anyway.
+
 2011-09-03  Lars Magne Ingebrigtsen  <larsi@gnus.org>
 
         * Require libxml/parser.h to avoid compilation warning.
diff --git a/src/indent.c b/src/indent.c
index 313315e9081..6e602d28f60 100644
--- a/src/indent.c
+++ b/src/indent.c
@@ -56,7 +56,7 @@ EMACS_INT last_known_column_point;
 static int last_known_column_modified;
 
 static EMACS_INT current_column_1 (void);
-static EMACS_INT position_indentation (int);
+static EMACS_INT position_indentation (ptrdiff_t);
 
 /* Cache of beginning of line found by the last call of
    current_column. */
@@ -855,7 +855,7 @@ following any initial whitespace.  */)
 }
 
 static EMACS_INT
-position_indentation (register int pos_byte)
+position_indentation (ptrdiff_t pos_byte)
 {
   register EMACS_INT column = 0;
   int tab_width = SANE_TAB_WIDTH (current_buffer);
@@ -2063,7 +2063,7 @@ whether or not it is currently displayed in some window.  */)
           /* Do this even if LINES is 0, so that we move back to the
              beginning of the current line as we ought.  */
           if (XINT (lines) == 0 || IT_CHARPOS (it) > 0)
-            move_it_by_lines (&it, XINT (lines));
+            move_it_by_lines (&it, max (INT_MIN, XINT (lines)));
         }
       else
         {
@@ -2083,7 +2083,7 @@ whether or not it is currently displayed in some window.  */)
                       && it.c == '\n'))
                 move_it_by_lines (&it, -1);
               it.vpos = 0;
-              move_it_by_lines (&it, XINT (lines));
+              move_it_by_lines (&it, min (INT_MAX, XINT (lines)));
             }
           else
             {
@@ -2099,12 +2099,12 @@ whether or not it is currently displayed in some window.  */)
                       move_it_by_lines (&it, 1);
                     }
                   if (XINT (lines) > 1)
-                    move_it_by_lines (&it, XINT (lines) - 1);
+                    move_it_by_lines (&it, min (INT_MAX, XINT (lines) - 1));
                 }
               else
                 {
                   it.vpos = 0;
-                  move_it_by_lines (&it, XINT (lines));
+                  move_it_by_lines (&it, min (INT_MAX, XINT (lines)));
                 }
             }
         }