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Issue #16350, part 2: Set unused_data (and unconsumed_tail) correctly in decompressobj().flush(). 

Additionally, fix a bug where a MemoryError in allocating a bytes object could
leave the decompressor object in an invalid state (with its unconsumed_tail
member being NULL).

Patch by Serhiy Storchaka.
This commit is contained in:
Nadeem Vawda 2012-11-11 02:14:15 +01:00
parent 67f089f860
commit 252f4dc6c9
3 changed files with 80 additions and 56 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

30
Lib/test/test_zlib.py
View File

@ -429,15 +429,27 @@ class CompressObjectTestCase(BaseCompressTestCase, unittest.TestCase):
def test_decompress_unused_data(self):
# Repeated calls to decompress() after EOF should accumulate data in
# dco.unused_data, instead of just storing the arg to the last call.
x = zlib.compress(HAMLET_SCENE) + HAMLET_SCENE
for step in 1, 2, 100:
dco = zlib.decompressobj()
data = b''.join(dco.decompress(x[i : i + step])
for i in range(0, len(x), step))
data += dco.flush()
self.assertEqual(data, HAMLET_SCENE)
self.assertEqual(dco.unused_data, HAMLET_SCENE)
source = b'abcdefghijklmnopqrstuvwxyz'
remainder = b'0123456789'
y = zlib.compress(source)
x = y + remainder
for maxlen in 0, 1000:
for step in 1, 2, len(y), len(x):
dco = zlib.decompressobj()
data = b''
for i in range(0, len(x), step):
if i < len(y):
self.assertEqual(dco.unused_data, b'')
if maxlen == 0:
data += dco.decompress(x[i : i + step])
self.assertEqual(dco.unconsumed_tail, b'')
else:
data += dco.decompress(
dco.unconsumed_tail + x[i : i + step], maxlen)
data += dco.flush()
self.assertEqual(data, source)
self.assertEqual(dco.unconsumed_tail, b'')
self.assertEqual(dco.unused_data, remainder)
if hasattr(zlib.decompressobj(), "copy"):
def test_decompresscopy(self):

6
Misc/NEWS
View File

@ -140,9 +140,11 @@ Core and Builtins
Library
-------
- Issue #16350: zlib.Decompress.decompress() now accumulates data from
- Issue #16350: zlib.decompressobj().decompress() now accumulates data from
successive calls after EOF in unused_data, instead of only saving the argument
to the last call. Patch by Serhiy Storchaka.
to the last call. decompressobj().flush() now correctly sets unused_data and
unconsumed_tail. A bug in the handling of MemoryError when setting the
unconsumed_tail attribute has also been fixed. Patch by Serhiy Storchaka.
- Issue #12759: sre_parse now raises a proper error when the name of the group
is missing. Initial patch by Serhiy Storchaka.

100
Modules/zlibmodule.c
View File

@ -467,6 +467,49 @@ PyZlib_objcompress(compobject *self, PyObject *args)
return RetVal;
}
/* Helper for objdecompress() and unflush(). Saves any unconsumed input data in
self->unused_data or self->unconsumed_tail, as appropriate. */
static int
save_unconsumed_input(compobject *self, int err)
{
if (err == Z_STREAM_END) {
/* The end of the compressed data has been reached. Store the leftover
input data in self->unused_data. */
if (self->zst.avail_in > 0) {
Py_ssize_t old_size = PyString_GET_SIZE(self->unused_data);
Py_ssize_t new_size;
PyObject *new_data;
if (self->zst.avail_in > PY_SSIZE_T_MAX - old_size) {
PyErr_NoMemory();
return -1;
}
new_size = old_size + self->zst.avail_in;
new_data = PyString_FromStringAndSize(NULL, new_size);
if (new_data == NULL)
return -1;
Py_MEMCPY(PyString_AS_STRING(new_data),
PyString_AS_STRING(self->unused_data), old_size);
Py_MEMCPY(PyString_AS_STRING(new_data) + old_size,
self->zst.next_in, self->zst.avail_in);
Py_DECREF(self->unused_data);
self->unused_data = new_data;
self->zst.avail_in = 0;
}
}
if (self->zst.avail_in > 0 || PyString_GET_SIZE(self->unconsumed_tail)) {
/* This code handles two distinct cases:
1. Output limit was reached. Save leftover input in unconsumed_tail.
2. All input data was consumed. Clear unconsumed_tail. */
PyObject *new_data = PyString_FromStringAndSize(
(char *)self->zst.next_in, self->zst.avail_in);
if (new_data == NULL)
return -1;
Py_DECREF(self->unconsumed_tail);
self->unconsumed_tail = new_data;
}
return 0;
}
PyDoc_STRVAR(decomp_decompress__doc__,
"decompress(data, max_length) -- Return a string containing the decompressed\n"
"version of the data.\n"
@ -541,60 +584,20 @@ PyZlib_objdecompress(compobject *self, PyObject *args)
Py_END_ALLOW_THREADS
}
if(max_length) {
/* Not all of the compressed data could be accommodated in a buffer of
the specified size. Return the unconsumed tail in an attribute. */
Py_DECREF(self->unconsumed_tail);
self->unconsumed_tail = PyString_FromStringAndSize((char *)self->zst.next_in,
self->zst.avail_in);
}
else if (PyString_GET_SIZE(self->unconsumed_tail) > 0) {
/* All of the compressed data was consumed. Clear unconsumed_tail. */
Py_DECREF(self->unconsumed_tail);
self->unconsumed_tail = PyString_FromStringAndSize("", 0);
}
if(!self->unconsumed_tail) {
if (save_unconsumed_input(self, err) < 0) {
Py_DECREF(RetVal);
RetVal = NULL;
goto error;
}
/* The end of the compressed data has been reached, so set the
unused_data attribute to a string containing the remainder of the
data in the string. Note that this is also a logical place to call
inflateEnd, but the old behaviour of only calling it on flush() is
preserved.
*/
if (err == Z_STREAM_END) {
if (self->zst.avail_in > 0) {
/* Append the leftover data to the existing value of unused_data. */
Py_ssize_t old_size = PyString_GET_SIZE(self->unused_data);
Py_ssize_t new_size = old_size + self->zst.avail_in;
PyObject *new_data;
if (new_size <= old_size) { /* Check for overflow. */
PyErr_NoMemory();
Py_DECREF(RetVal);
RetVal = NULL;
goto error;
}
new_data = PyString_FromStringAndSize(NULL, new_size);
if (new_data == NULL) {
Py_DECREF(RetVal);
RetVal = NULL;
goto error;
}
Py_MEMCPY(PyString_AS_STRING(new_data),
PyString_AS_STRING(self->unused_data), old_size);
Py_MEMCPY(PyString_AS_STRING(new_data) + old_size,
self->zst.next_in, self->zst.avail_in);
Py_DECREF(self->unused_data);
self->unused_data = new_data;
}
/* This is the logical place to call inflateEnd, but the old behaviour of
only calling it on flush() is preserved. */
if (err != Z_STREAM_END && err != Z_OK && err != Z_BUF_ERROR) {
/* We will only get Z_BUF_ERROR if the output buffer was full
but there wasn't more output when we tried again, so it is
not an error condition.
*/
} else if (err != Z_OK && err != Z_BUF_ERROR) {
zlib_error(self->zst, err, "while decompressing");
Py_DECREF(RetVal);
RetVal = NULL;
@ -848,6 +851,12 @@ PyZlib_unflush(compobject *self, PyObject *args)
Py_END_ALLOW_THREADS
}
if (save_unconsumed_input(self, err) < 0) {
Py_DECREF(retval);
retval = NULL;
goto error;
}
/* If flushmode is Z_FINISH, we also have to call deflateEnd() to free
various data structures. Note we should only get Z_STREAM_END when
flushmode is Z_FINISH */
@ -861,6 +870,7 @@ PyZlib_unflush(compobject *self, PyObject *args)
goto error;
}
}
_PyString_Resize(&retval, self->zst.total_out - start_total_out);
error: