This makes it unnecessary to copy back the state, and also relaxes
the requirements on callbacks (bytes_left will always be valid).
It decreases code size by a few bytes, but may be just slightly slower.
-/* Decode string length from stream and return a substream with limited length.
- * Before disposing the substream, remember to copy the substream->state back
- * to stream->state.
- */
+/* Decode string length from stream and return a substream with limited length. */
+static bool substream_callback(pb_istream_t *stream, uint8_t *buf, size_t count)
+{
+ pb_istream_t *parent = (pb_istream_t*)stream->state;
+ return pb_read(parent, buf, count);
+}
+
static bool checkreturn make_string_substream(pb_istream_t *stream, pb_istream_t *substream)
{
uint32_t size;
if (!pb_decode_varint32(stream, &size))
return false;
static bool checkreturn make_string_substream(pb_istream_t *stream, pb_istream_t *substream)
{
uint32_t size;
if (!pb_decode_varint32(stream, &size))
return false;
- *substream = *stream;
- if (substream->bytes_left < size)
+ if (stream->bytes_left < size)
+ substream->callback = &substream_callback;
+ substream->state = stream;
substream->bytes_left = size;
substream->bytes_left = size;
- stream->bytes_left -= size;
&& PB_LTYPE(iter->current->type) <= PB_LTYPE_LAST_PACKABLE)
{
/* Packed array */
&& PB_LTYPE(iter->current->type) <= PB_LTYPE_LAST_PACKABLE)
{
/* Packed array */
size_t *size = (size_t*)iter->pSize;
pb_istream_t substream;
if (!make_string_substream(stream, &substream))
size_t *size = (size_t*)iter->pSize;
pb_istream_t substream;
if (!make_string_substream(stream, &substream))
return false;
(*size)++;
}
return false;
(*size)++;
}
- status = (substream.bytes_left == 0);
- stream->state = substream.state;
- return status;
+ return (substream.bytes_left == 0);
- stream->state = substream.state;
bool checkreturn pb_dec_submessage(pb_istream_t *stream, const pb_field_t *field, void *dest)
{
bool checkreturn pb_dec_submessage(pb_istream_t *stream, const pb_field_t *field, void *dest)
{
pb_istream_t substream;
if (!make_string_substream(stream, &substream))
pb_istream_t substream;
if (!make_string_substream(stream, &substream))
if (field->ptr == NULL)
return false;
if (field->ptr == NULL)
return false;
- status = pb_decode(&substream, (pb_field_t*)field->ptr, dest);
- stream->state = substream.state;
- return status;
+ return pb_decode(&substream, (pb_field_t*)field->ptr, dest);
*
* 3) You can use state to store your own data (e.g. buffer pointer),
* and rely on pb_read to verify that no-body reads past bytes_left.
*
* 3) You can use state to store your own data (e.g. buffer pointer),
* and rely on pb_read to verify that no-body reads past bytes_left.
- *
- * 4) Your callback may be used with substreams, in which case bytes_left
- * is different than from the main stream. Don't use bytes_left to compute
- * any pointers.
*/
struct _pb_istream_t
{
*/
struct _pb_istream_t
{