Commit 2a47c44d authored by Paul Eggert's avatar Paul Eggert

* fileio.c (Finsert_file_contents): Avoid signed integer overflow.

parent a37c69bf
2011-04-02 Paul Eggert <eggert@cs.ucla.edu>
* fileio.c (Finsert_file_contents): Avoid signed integer overflow.
* minibuf.c (read_minibuf_noninteractive): Use size_t for sizes.
Check for integer overflow on size calculations.
......@@ -3239,9 +3239,16 @@ variable `last-coding-system-used' to the coding system actually used. */)
record_unwind_protect (close_file_unwind, make_number (fd));
/* Can happen on any platform that uses long as type of off_t, but allows
file sizes to exceed 2Gb, so give a suitable message. */
if (! not_regular && st.st_size < 0)
/* Arithmetic overflow can occur if an Emacs integer cannot represent the
file size, or if the calculations below overflow. The calculations below
double the file size twice, so check that it can be multiplied by 4
safely.
Also check whether the size is negative, which can happen on a platform
that allows file sizes greater than the maximum off_t value. */
if (! not_regular
&& ! (0 <= st.st_size && st.st_size <= MOST_POSITIVE_FIXNUM / 4))
error ("Maximum buffer size exceeded");
/* Prevent redisplay optimizations. */
......@@ -3268,18 +3275,6 @@ variable `last-coding-system-used' to the coding system actually used. */)
{
XSETINT (end, st.st_size);
/* Arithmetic overflow can occur if an Emacs integer cannot
represent the file size, or if the calculations below
overflow. The calculations below double the file size
twice, so check that it can be multiplied by 4 safely. */
if (XINT (end) != st.st_size
/* Actually, it should test either INT_MAX or LONG_MAX
depending on which one is used for EMACS_INT. But in
any case, in practice, this test is redundant with the
one above.
|| st.st_size > INT_MAX / 4 */)
error ("Maximum buffer size exceeded");
/* The file size returned from stat may be zero, but data
may be readable nonetheless, for example when this is a
file in the /proc filesystem. */
......
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