* fileio.c: Fix bugs with large file offsets.

The previous code assumed that file offsets (off_t values) fit in
EMACS_INT variables, which is not true on typical 32-bit hosts.
The code messed up by falsely reporting buffer overflow in cases
such as (insert-file-contents "big" nil 1 2) into an empty buffer
when "big" contains more than 2**29 bytes, even though this
inserts just one byte and does not overflow the buffer.
(Finsert_file_contents): Store file offsets as off_t
values, not as EMACS_INT values.  Check for overflow when
converting between EMACS_INT and off_t.  When checking for
buffer overflow or for overlap, take the offsets into account.
Don't use EMACS_INT for small values where int suffices.
When checking for overlap, fix a typo: ZV was used where
ZV_BYTE was intended.
(Fwrite_region): Don't assume off_t fits into 'long'.
* buffer.h (struct buffer.modtime_size): Now off_t, not EMACS_INT.

1 files changed, 19 insertions, 0 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index 52ec796d6cf..c80a12c1c00 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,22 @@
+2011-09-03  Paul Eggert  <eggert@cs.ucla.edu>
+
+        * fileio.c: Fix bugs with large file offsets.
+        The previous code assumed that file offsets (off_t values) fit in
+        EMACS_INT variables, which is not true on typical 32-bit hosts.
+        The code messed up by falsely reporting buffer overflow in cases
+        such as (insert-file-contents "big" nil 1 2) into an empty buffer
+        when "big" contains more than 2**29 bytes, even though this
+        inserts just one byte and does not overflow the buffer.
+        (Finsert_file_contents): Store file offsets as off_t
+        values, not as EMACS_INT values.  Check for overflow when
+        converting between EMACS_INT and off_t.  When checking for
+        buffer overflow or for overlap, take the offsets into account.
+        Don't use EMACS_INT for small values where int suffices.
+        When checking for overlap, fix a typo: ZV was used where
+        ZV_BYTE was intended.
+        (Fwrite_region): Don't assume off_t fits into 'long'.
+        * buffer.h (struct buffer.modtime_size): Now off_t, not EMACS_INT.
+
 2011-08-30  Chong Yidong  <cyd@stupidchicken.com>
 
         * syntax.c (find_defun_start): Update all cache variables if