Fix coding-related core dumps with gcc -ftrapv.

The code was computing A - B, where A and B are pointers, and B is
random garbage.  This can lead to core dumps on platforms that
have special pointer registers, and it also leads to core dumps on
x86-64 when compiled with gcc -ftrapv.  The fix is to compute
A - B only when B is initialized properly.
* coding.c (coding_set_source, coding_set_destination): Return void.
(coding_change_source, coding_change_destinations): New functions,
with the old behaviors of coding_set_source and coding_set_destination.
All callers that need an offset changed to use these new functions.

1 files changed, 13 insertions, 0 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index bea9b4fbc47..1ade4691184 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,16 @@
+2012-05-26  Paul Eggert  <eggert@cs.ucla.edu>
+
+        Fix coding-related core dumps with gcc -ftrapv.
+        The code was computing A - B, where A and B are pointers, and B is
+        random garbage.  This can lead to core dumps on platforms that
+        have special pointer registers, and it also leads to core dumps on
+        x86-64 when compiled with gcc -ftrapv.  The fix is to compute
+        A - B only when B is initialized properly.
+        * coding.c (coding_set_source, coding_set_destination): Return void.
+        (coding_change_source, coding_change_destinations): New functions,
+        with the old behaviors of coding_set_source and coding_set_destination.
+        All callers that need an offset changed to use these new functions.
+
 2012-05-26  Glenn Morris  <rgm@gnu.org>
 
         * nsterm.m (ns_init_paths): Don't mess with INFOPATH.  (Bug#2791)