Issue #16350: Fix zlib decompressor handling of unused_data with multiple calls to decompress() after EOF.
Patch by Serhiy Storchaka.
diff --git a/Modules/zlibmodule.c b/Modules/zlibmodule.c
index 035aa8e..95e85b5 100644
--- a/Modules/zlibmodule.c
+++ b/Modules/zlibmodule.c
@@ -566,12 +566,29 @@
preserved.
*/
if (err == Z_STREAM_END) {
- Py_XDECREF(self->unused_data); /* Free original empty string */
- self->unused_data = PyString_FromStringAndSize(
- (char *)self->zst.next_in, self->zst.avail_in);
- if (self->unused_data == NULL) {
- Py_DECREF(RetVal);
- goto error;
+ 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;
}
/* 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