[Python-checkins] r85625 - python/branches/release25-maint/Modules/audioop.c
matthias.klose
python-checkins at python.org
Sun Oct 17 12:34:40 CEST 2010
Author: matthias.klose
Date: Sun Oct 17 12:34:40 2010
New Revision: 85625
Log:
Merge r81080 from the python2.6 branch:
Issue #8674: fix another bogus overflow check in audioop module.
Modified:
python/branches/release25-maint/Modules/audioop.c
Modified: python/branches/release25-maint/Modules/audioop.c
==============================================================================
--- python/branches/release25-maint/Modules/audioop.c (original)
+++ python/branches/release25-maint/Modules/audioop.c Sun Oct 17 12:34:40 2010
@@ -1150,25 +1150,16 @@
ceiling(len*outrate/inrate) output frames, and each frame
requires bytes_per_frame bytes. Computing this
without spurious overflow is the challenge; we can
- settle for a reasonable upper bound, though. */
- int ceiling; /* the number of output frames */
- int nbytes; /* the number of output bytes needed */
- int q = len / inrate;
- /* Now len = q * inrate + r exactly (with r = len % inrate),
- and this is less than q * inrate + inrate = (q+1)*inrate.
- So a reasonable upper bound on len*outrate/inrate is
- ((q+1)*inrate)*outrate/inrate =
- (q+1)*outrate.
- */
- ceiling = (q+1) * outrate;
- nbytes = ceiling * bytes_per_frame;
- /* See whether anything overflowed; if not, get the space. */
- if (q+1 < 0 ||
- ceiling / outrate != q+1 ||
- nbytes / bytes_per_frame != ceiling)
+ settle for a reasonable upper bound, though, in this
+ case ceiling(len/inrate) * outrate. */
+
+ /* compute ceiling(len/inrate) without overflow */
+ int q = len > 0 ? 1 + (len - 1) / inrate : 0;
+ if (outrate > INT_MAX / q / bytes_per_frame)
str = NULL;
else
- str = PyString_FromStringAndSize(NULL, nbytes);
+ str = PyString_FromStringAndSize(NULL,
+ q * outrate * bytes_per_frame);
if (str == NULL) {
PyErr_SetString(PyExc_MemoryError,
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