diff options
| -rw-r--r-- | Objects/longobject.c | 27 |
1 files changed, 18 insertions, 9 deletions
diff --git a/Objects/longobject.c b/Objects/longobject.c index f8a9129..44819701 100644 --- a/Objects/longobject.c +++ b/Objects/longobject.c @@ -424,18 +424,27 @@ _PyLong_AsByteArray(PyLongObject* v, *p = (unsigned char)(accum & 0xff); p += pincr; } - - /* Fill remaining bytes with copies of the sign bit. */ - for ( ; j < n; ++j, p += pincr) - *p = (unsigned char)(do_twos_comp ? 0xff : 0); - - /* Check for delicate overflow (not enough room for the sign bit). */ - if (j > 0 && is_signed) { + else if (j == n && n > 0 && is_signed) { + /* The main loop filled the byte array exactly, so the code + just above didn't get to ensure there's a sign bit, and the + loop below wouldn't add one either. Make sure a sign bit + exists. */ unsigned char msb = *(p - pincr); - int sign_bit_set = (msb & 0x80) != 0; - if (sign_bit_set != do_twos_comp) + int sign_bit_set = msb >= 0x80; + assert(accumbits == 0); + if (sign_bit_set == do_twos_comp) + return 0; + else goto Overflow; } + + /* Fill remaining bytes with copies of the sign bit. */ + { + unsigned char signbyte = do_twos_comp ? 0xffU : 0U; + for ( ; j < n; ++j, p += pincr) + *p = signbyte; + } + return 0; Overflow: |