Issue #12213: Fix a buffering bug with interleaved reads and writes that
could appear on BufferedRandom streams.
diff --git a/Modules/_io/bufferedio.c b/Modules/_io/bufferedio.c
index cdaa36e..a8631e0 100644
--- a/Modules/_io/bufferedio.c
+++ b/Modules/_io/bufferedio.c
@@ -753,6 +753,28 @@
*/
static PyObject *
+buffered_flush_and_rewind_unlocked(buffered *self)
+{
+ PyObject *res;
+
+ res = _bufferedwriter_flush_unlocked(self, 0);
+ if (res == NULL)
+ return NULL;
+ Py_DECREF(res);
+
+ if (self->readable) {
+ /* Rewind the raw stream so that its position corresponds to
+ the current logical position. */
+ Py_off_t n;
+ n = _buffered_raw_seek(self, -RAW_OFFSET(self), 1);
+ _bufferedreader_reset_buf(self);
+ if (n == -1)
+ return NULL;
+ }
+ Py_RETURN_NONE;
+}
+
+static PyObject *
buffered_flush(buffered *self, PyObject *args)
{
PyObject *res;
@@ -762,16 +784,7 @@
if (!ENTER_BUFFERED(self))
return NULL;
- res = _bufferedwriter_flush_unlocked(self, 0);
- if (res != NULL && self->readable) {
- /* Rewind the raw stream so that its position corresponds to
- the current logical position. */
- Py_off_t n;
- n = _buffered_raw_seek(self, -RAW_OFFSET(self), 1);
- if (n == -1)
- Py_CLEAR(res);
- _bufferedreader_reset_buf(self);
- }
+ res = buffered_flush_and_rewind_unlocked(self);
LEAVE_BUFFERED(self)
return res;
@@ -792,7 +805,7 @@
return NULL;
if (self->writable) {
- res = _bufferedwriter_flush_unlocked(self, 1);
+ res = buffered_flush_and_rewind_unlocked(self);
if (res == NULL)
goto end;
Py_CLEAR(res);
@@ -827,19 +840,18 @@
if (!ENTER_BUFFERED(self))
return NULL;
res = _bufferedreader_read_all(self);
- LEAVE_BUFFERED(self)
}
else {
res = _bufferedreader_read_fast(self, n);
- if (res == Py_None) {
- Py_DECREF(res);
- if (!ENTER_BUFFERED(self))
- return NULL;
- res = _bufferedreader_read_generic(self, n);
- LEAVE_BUFFERED(self)
- }
+ if (res != Py_None)
+ return res;
+ Py_DECREF(res);
+ if (!ENTER_BUFFERED(self))
+ return NULL;
+ res = _bufferedreader_read_generic(self, n);
}
+ LEAVE_BUFFERED(self)
return res;
}
@@ -865,13 +877,6 @@
if (!ENTER_BUFFERED(self))
return NULL;
- if (self->writable) {
- res = _bufferedwriter_flush_unlocked(self, 1);
- if (res == NULL)
- goto end;
- Py_CLEAR(res);
- }
-
/* Return up to n bytes. If at least one byte is buffered, we
only return buffered bytes. Otherwise, we do one raw read. */
@@ -891,6 +896,13 @@
goto end;
}
+ if (self->writable) {
+ res = buffered_flush_and_rewind_unlocked(self);
+ if (res == NULL)
+ goto end;
+ Py_DECREF(res);
+ }
+
/* Fill the buffer from the raw stream, and copy it to the result. */
_bufferedreader_reset_buf(self);
r = _bufferedreader_fill_buffer(self);
@@ -939,7 +951,7 @@
goto end_unlocked;
if (self->writable) {
- res = _bufferedwriter_flush_unlocked(self, 0);
+ res = buffered_flush_and_rewind_unlocked(self);
if (res == NULL)
goto end;
Py_CLEAR(res);
@@ -1022,12 +1034,6 @@
goto end_unlocked;
/* Now we try to get some more from the raw stream */
- if (self->writable) {
- res = _bufferedwriter_flush_unlocked(self, 1);
- if (res == NULL)
- goto end;
- Py_CLEAR(res);
- }
chunks = PyList_New(0);
if (chunks == NULL)
goto end;
@@ -1041,9 +1047,16 @@
}
Py_CLEAR(res);
written += n;
+ self->pos += n;
if (limit >= 0)
limit -= n;
}
+ if (self->writable) {
+ PyObject *r = buffered_flush_and_rewind_unlocked(self);
+ if (r == NULL)
+ goto end;
+ Py_DECREF(r);
+ }
for (;;) {
_bufferedreader_reset_buf(self);
@@ -1212,20 +1225,11 @@
return NULL;
if (self->writable) {
- res = _bufferedwriter_flush_unlocked(self, 0);
+ res = buffered_flush_and_rewind_unlocked(self);
if (res == NULL)
goto end;
Py_CLEAR(res);
}
- if (self->readable) {
- if (pos == Py_None) {
- /* Rewind the raw stream so that its position corresponds to
- the current logical position. */
- if (_buffered_raw_seek(self, -RAW_OFFSET(self), 1) == -1)
- goto end;
- }
- _bufferedreader_reset_buf(self);
- }
res = PyObject_CallMethodObjArgs(self->raw, _PyIO_str_truncate, pos, NULL);
if (res == NULL)
goto end;
@@ -1416,15 +1420,16 @@
self->buffer + self->pos, current_size);
if (data == NULL)
return NULL;
+ self->pos += current_size;
}
- _bufferedreader_reset_buf(self);
/* We're going past the buffer's bounds, flush it */
if (self->writable) {
- res = _bufferedwriter_flush_unlocked(self, 1);
+ res = buffered_flush_and_rewind_unlocked(self);
if (res == NULL)
return NULL;
Py_CLEAR(res);
}
+ _bufferedreader_reset_buf(self);
if (PyObject_HasAttr(self->raw, _PyIO_str_readall)) {
chunk = PyObject_CallMethodObjArgs(self->raw, _PyIO_str_readall, NULL);
@@ -1540,6 +1545,14 @@
memcpy(out, self->buffer + self->pos, current_size);
remaining -= current_size;
written += current_size;
+ self->pos += current_size;
+ }
+ /* Flush the write buffer if necessary */
+ if (self->writable) {
+ PyObject *r = buffered_flush_and_rewind_unlocked(self);
+ if (r == NULL)
+ goto error;
+ Py_DECREF(r);
}
_bufferedreader_reset_buf(self);
while (remaining > 0) {