[Python-checkins] PyLong_FromString(): fix Coverity CID 1424951 (#4738)

Thu Dec 7 18:06:57 EST 2017

https://github.com/python/cpython/commit/dd431b32f4a599fff9c9cddfe9d48cc66b347481
commit: dd431b32f4a599fff9c9cddfe9d48cc66b347481
branch: master
author: Victor Stinner <victor.stinner at gmail.com>
committer: GitHub <noreply at github.com>
date: 2017年12月08日T00:06:55+01:00
summary:
PyLong_FromString(): fix Coverity CID 1424951 (#4738)
Explicitly cast digits (Py_ssize_t) to double to fix the following
false-alarm warning from Coverity:
"fsize_z = digits * log_base_BASE[base] + 1;"
CID 1424951: Incorrect expression (UNINTENDED_INTEGER_DIVISION)
Dividing integer expressions "9223372036854775783UL" and "4UL", and
then converting the integer quotient to type "double". Any remainder,
or fractional part of the quotient, is ignored.
files:
M Objects/longobject.c

diff --git a/Objects/longobject.c b/Objects/longobject.c
index a7f496825eb..269d6cdea59 100644
--- a/Objects/longobject.c
+++ b/Objects/longobject.c
@@ -2267,7 +2267,6 @@ just 1 digit at the start, so that the copying code was exercised for every
 digit beyond the first.
 ***/
 twodigits c; /* current input character */
- double fsize_z;
 Py_ssize_t size_z;
 Py_ssize_t digits = 0;
 int i;
@@ -2331,8 +2330,8 @@ digit beyond the first.
 * need to initialize z->ob_digit -- no slot is read up before
 * being stored into.
 */
- fsize_z = digits * log_base_BASE[base] + 1;
- if (fsize_z > MAX_LONG_DIGITS) {
+ double fsize_z = (double)digits * log_base_BASE[base] + 1.0;
+ if (fsize_z > (double)MAX_LONG_DIGITS) {
 /* The same exception as in _PyLong_New(). */
 PyErr_SetString(PyExc_OverflowError,
 "too many digits in integer");
