diff options
Diffstat (limited to 'Objects/stringlib/string_format.h')
| -rw-r--r-- | Objects/stringlib/string_format.h | 15 |
1 files changed, 6 insertions, 9 deletions
diff --git a/Objects/stringlib/string_format.h b/Objects/stringlib/string_format.h index 6c7adcb..c46bdc2 100644 --- a/Objects/stringlib/string_format.h +++ b/Objects/stringlib/string_format.h @@ -197,7 +197,6 @@ get_integer(const SubString *str) { Py_ssize_t accumulator = 0; Py_ssize_t digitval; - Py_ssize_t oldaccumulator; STRINGLIB_CHAR *p; /* empty string is an error */ @@ -209,19 +208,17 @@ get_integer(const SubString *str) if (digitval < 0) return -1; /* - This trick was copied from old Unicode format code. It's cute, - but would really suck on an old machine with a slow divide - implementation. Fortunately, in the normal case we do not - expect too many digits. + Detect possible overflow before it happens: + + accumulator * 10 + digitval > PY_SSIZE_T_MAX if and only if + accumulator > (PY_SSIZE_T_MAX - digitval) / 10. */ - oldaccumulator = accumulator; - accumulator *= 10; - if ((accumulator+10)/10 != oldaccumulator+1) { + if (accumulator > (PY_SSIZE_T_MAX - digitval) / 10) { PyErr_Format(PyExc_ValueError, "Too many decimal digits in format string"); return -1; } - accumulator += digitval; + accumulator = accumulator * 10 + digitval; } return accumulator; } |