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Issue #5981: Fix some float.fromhex bugs related to inf and nan handling.

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This commit is contained in:
Mark Dickinson 2009-05-11 15:33:08 +00:00
parent 68e27eb834
commit b1d45856c2
3 changed files with 73 additions and 16 deletions
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52
Objects/floatobject.c
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@ -1159,6 +1159,20 @@ Return a hexadecimal representation of a floating-point number.\n\
>>> 3.14159.hex()\n\
'0x1.921f9f01b866ep+1'");
/* Case-insensitive locale-independent string match used for nan and inf
detection. t should be lower-case and null-terminated. Return a nonzero
result if the first strlen(t) characters of s match t and 0 otherwise. */
static int
case_insensitive_match(const char *s, const char *t)
{
while(*t && Py_TOLOWER(*s) == *t) {
s++;
t++;
}
return *t ? 0 : 1;
}
/* Convert a hexadecimal string to a float. */
static PyObject *
@ -1235,13 +1249,20 @@ float_fromhex(PyObject *cls, PyObject *arg)
s++;
/* infinities and nans */
if (PyOS_strnicmp(s, "nan", 4) == 0) {
x = Py_NAN;
if (*s == 'i' || *s == 'I') {
if (!case_insensitive_match(s+1, "nf"))
goto parse_error;
s += 3;
x = Py_HUGE_VAL;
if (case_insensitive_match(s, "inity"))
s += 5;
goto finished;
}
if (PyOS_strnicmp(s, "inf", 4) == 0 ||
PyOS_strnicmp(s, "infinity", 9) == 0) {
x = sign*Py_HUGE_VAL;
if (*s == 'n' || *s == 'N') {
if (!case_insensitive_match(s+1, "an"))
goto parse_error;
s += 3;
x = Py_NAN;
goto finished;
}
@ -1294,12 +1315,6 @@ float_fromhex(PyObject *cls, PyObject *arg)
else
exp = 0;
/* optional trailing whitespace leading to the end of the string */
while (Py_ISSPACE(*s))
s++;
if (s != s_end)
goto parse_error;
/* for 0 <= j < ndigits, HEX_DIGIT(j) gives the jth most significant digit */
#define HEX_DIGIT(j) hex_from_char(*((j) < fdigits ? \
coeff_end-(j) : \
@ -1313,7 +1328,7 @@ float_fromhex(PyObject *cls, PyObject *arg)
while (ndigits > 0 && HEX_DIGIT(ndigits-1) == 0)
ndigits--;
if (ndigits == 0 || exp < LONG_MIN/2) {
x = sign * 0.0;
x = 0.0;
goto finished;
}
if (exp > LONG_MAX/2)
@ -1329,7 +1344,7 @@ float_fromhex(PyObject *cls, PyObject *arg)
/* catch almost all nonextreme cases of overflow and underflow here */
if (top_exp < DBL_MIN_EXP - DBL_MANT_DIG) {
x = sign * 0.0;
x = 0.0;
goto finished;
}
if (top_exp > DBL_MAX_EXP)
@ -1344,7 +1359,7 @@ float_fromhex(PyObject *cls, PyObject *arg)
/* no rounding required */
for (i = ndigits-1; i >= 0; i--)
x = 16.0*x + HEX_DIGIT(i);
x = sign * ldexp(x, (int)(exp));
x = ldexp(x, (int)(exp));
goto finished;
}
/* rounding required. key_digit is the index of the hex digit
@ -1378,10 +1393,15 @@ float_fromhex(PyObject *cls, PyObject *arg)
goto overflow_error;
}
}
x = sign * ldexp(x, (int)(exp+4*key_digit));
x = ldexp(x, (int)(exp+4*key_digit));
finished:
result_as_float = Py_BuildValue("(d)", x);
/* optional trailing whitespace leading to the end of the string */
while (Py_ISSPACE(*s))
s++;
if (s != s_end)
goto parse_error;
result_as_float = Py_BuildValue("(d)", sign * x);
if (result_as_float == NULL)
return NULL;
result = PyObject_CallObject(cls, result_as_float);