Improve buffer-overflow checking.

* fileio.c (Finsert_file_contents):
* insdel.c (insert_from_buffer_1, replace_range, replace_range_2):
Remove the old (too-loose) buffer overflow checks.
They weren't needed, since make_gap checks for buffer overflow.
* insdel.c (make_gap_larger): Catch buffer overflows that were missed.
The old code merely checked for Emacs fixnum overflow, and relied
on undefined (wraparound) behavior.  The new code avoids undefined
behavior, and also checks for ptrdiff_t and/or size_t overflow.

1 files changed, 1 insertions, 10 deletions

diff --git a/src/fileio.c b/src/fileio.c
index 4458a3a4807..dd34872c263 100644
--- a/src/fileio.c
+++ b/src/fileio.c
@@ -3800,16 +3800,7 @@ variable `last-coding-system-used' to the coding system actually used.  */)
     }
 
   if (! not_regular)
-    {
-      register Lisp_Object temp;
-
-      total = XINT (end) - XINT (beg);
-
-      /* Make sure point-max won't overflow after this insertion.  */
-      XSETINT (temp, total);
-      if (total != XINT (temp))
-	buffer_overflow ();
-    }
+    total = XINT (end) - XINT (beg);
   else
     /* For a special file, all we can do is guess.  */
     total = READ_BUF_SIZE;