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bpo-39681: Fix C pickle regression with minimal file-like objects (#18592)

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Fix a regression where the C pickle module wouldn't allow unpickling from a
file-like object that doesn't expose a readinto() method.
This commit is contained in:
Antoine Pitrou 2020-02-23 23:33:53 +01:00 • committed by GitHub
parent b76518d43f
commit 9f37872e30
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GPG key ID: 4AEE18F83AFDEB23
3 changed files with 59 additions and 9 deletions
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41
Modules/_pickle.c
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@ -1373,13 +1373,42 @@ _Unpickler_ReadInto(UnpicklerObject *self, char *buf, Py_ssize_t n)
}
/* Read from file */
if (!self->readinto) {
if (!self->read) {
/* We're unpickling memory, this means the input is truncated */
return bad_readline();
}
if (_Unpickler_SkipConsumed(self) < 0) {
return -1;
}
if (!self->readinto) {
/* readinto() not supported on file-like object, fall back to read()
* and copy into destination buffer (bpo-39681) */
PyObject* len = PyLong_FromSsize_t(n);
if (len == NULL) {
return -1;
}
PyObject* data = _Pickle_FastCall(self->read, len);
if (data == NULL) {
return -1;
}
if (!PyBytes_Check(data)) {
PyErr_Format(PyExc_ValueError,
"read() returned non-bytes object (%R)",
Py_TYPE(data));
Py_DECREF(data);
return -1;
}
Py_ssize_t read_size = PyBytes_GET_SIZE(data);
if (read_size < n) {
Py_DECREF(data);
return bad_readline();
}
memcpy(buf, PyBytes_AS_STRING(data), n);
Py_DECREF(data);
return n;
}
/* Call readinto() into user buffer */
PyObject *buf_obj = PyMemoryView_FromMemory(buf, n, PyBUF_WRITE);
if (buf_obj == NULL) {
@ -1608,17 +1637,19 @@ _Unpickler_SetInputStream(UnpicklerObject *self, PyObject *file)
_Py_IDENTIFIER(readinto);
_Py_IDENTIFIER(readline);
/* Optional file methods */
if (_PyObject_LookupAttrId(file, &PyId_peek, &self->peek) < 0) {
return -1;
}
if (_PyObject_LookupAttrId(file, &PyId_readinto, &self->readinto) < 0) {
return -1;
}
(void)_PyObject_LookupAttrId(file, &PyId_read, &self->read);
(void)_PyObject_LookupAttrId(file, &PyId_readinto, &self->readinto);
(void)_PyObject_LookupAttrId(file, &PyId_readline, &self->readline);
if (!self->readline || !self->readinto || !self->read) {
if (!self->readline || !self->read) {
if (!PyErr_Occurred()) {
PyErr_SetString(PyExc_TypeError,
"file must have 'read', 'readinto' and "
"'readline' attributes");
"file must have 'read' and 'readline' attributes");
}
Py_CLEAR(self->read);
Py_CLEAR(self->readinto);