Commit c9aa58e6 authored by Damien George's avatar Damien George
Browse files

py: Improve handling of long-int overflow.

This removes mpz_as_int, since that was a terrible function (it
implemented saturating conversion).

Use mpz_as_int_checked and mpz_as_uint_checked.  These now work
correctly (they previously had wrong overflow checking, eg
print(chr(10000000000000)) on 32-bit machine would incorrectly convert
this large number to a small int).
parent 94fbe971
......@@ -175,7 +175,7 @@ MP_DEFINE_CONST_FUN_OBJ_1(mp_builtin_callable_obj, mp_builtin_callable);
STATIC mp_obj_t mp_builtin_chr(mp_obj_t o_in) {
#if MICROPY_PY_BUILTINS_STR_UNICODE
mp_int_t c = mp_obj_get_int(o_in);
mp_uint_t c = mp_obj_get_int(o_in);
char str[4];
int len = 0;
if (c < 0x80) {
......
......@@ -1229,49 +1229,41 @@ mp_int_t mpz_hash(const mpz_t *z) {
return val;
}
// TODO check that this correctly handles overflow in all cases
mp_int_t mpz_as_int(const mpz_t *i) {
bool mpz_as_int_checked(const mpz_t *i, mp_int_t *value) {
mp_int_t val = 0;
mpz_dig_t *d = i->dig + i->len;
while (--d >= i->dig) {
mp_int_t oldval = val;
val = (val << DIG_SIZE) | *d;
if (val < oldval) {
// overflow, return +/- "infinity"
if (i->neg == 0) {
// +infinity
return ~WORD_MSBIT_HIGH;
} else {
// -infinity
return WORD_MSBIT_HIGH;
}
if (val > (~(WORD_MSBIT_HIGH) >> DIG_SIZE)) {
// will overflow
return false;
}
val = (val << DIG_SIZE) | *d;
}
if (i->neg != 0) {
val = -val;
}
return val;
*value = val;
return true;
}
// TODO check that this correctly handles overflow in all cases
bool mpz_as_int_checked(const mpz_t *i, mp_int_t *value) {
mp_int_t val = 0;
bool mpz_as_uint_checked(const mpz_t *i, mp_uint_t *value) {
if (i->neg != 0) {
// can't represent signed values
return false;
}
mp_uint_t val = 0;
mpz_dig_t *d = i->dig + i->len;
while (--d >= i->dig) {
mp_int_t oldval = val;
val = (val << DIG_SIZE) | *d;
if (val < oldval) {
// overflow
if (val > ((~0) >> DIG_SIZE)) {
// will overflow
return false;
}
}
if (i->neg != 0) {
val = -val;
val = (val << DIG_SIZE) | *d;
}
*value = val;
......
......@@ -97,8 +97,8 @@ mpz_t *mpz_div(const mpz_t *lhs, const mpz_t *rhs);
mpz_t *mpz_mod(const mpz_t *lhs, const mpz_t *rhs);
mp_int_t mpz_hash(const mpz_t *z);
mp_int_t mpz_as_int(const mpz_t *z);
bool mpz_as_int_checked(const mpz_t *z, mp_int_t *value);
bool mpz_as_uint_checked(const mpz_t *z, mp_uint_t *value);
#if MICROPY_PY_BUILTINS_FLOAT
mp_float_t mpz_as_float(const mpz_t *z);
#endif
......
......@@ -225,8 +225,7 @@ mp_obj_t mp_obj_int_binary_op(int op, mp_obj_t lhs_in, mp_obj_t rhs_in) {
case MP_BINARY_OP_INPLACE_LSHIFT:
case MP_BINARY_OP_RSHIFT:
case MP_BINARY_OP_INPLACE_RSHIFT: {
// TODO check conversion overflow
mp_int_t irhs = mpz_as_int(zrhs);
mp_int_t irhs = mp_obj_int_get_checked(rhs_in);
if (irhs < 0) {
nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, "negative shift count"));
}
......@@ -303,7 +302,8 @@ mp_int_t mp_obj_int_get(mp_const_obj_t self_in) {
return MP_OBJ_SMALL_INT_VALUE(self_in);
} else {
const mp_obj_int_t *self = self_in;
return mpz_as_int(&self->mpz);
// TODO this is a hack until we remove mp_obj_int_get function entirely
return mpz_hash(&self->mpz);
}
}
......
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