libFLAC: More metadata_iterators fixes
The previous fixes for metadata_iterators didn't completely fix the problem.
The behavior of chain_prepare_for_write_() must always be the same as the
behavior of FLAC__metadata_chain_check_if_tempfile_needed(). Before this
fix, one check was missing in FLAC__metadata_chain_check_if_tempfile_needed(),
and also chain_prepare_for_write_() checked the sizes of the metadata blocks
*after* making the changes to the chain, while
FLAC__metadata_chain_check_if_tempfile_needed() does it *before* the changes.
This patch changes FLAC__metadata_chain_check_if_tempfile_needed() so that it
keeps some info (lbs_state, lbs_size) about estimated changes and then uses
it to check the block sizes.
It also simplifies FLAC__metadata_chain_check_if_tempfile_needed() a little.
Patch-from: lvqcl <lvqcl.mail@gmail.com>
diff --git a/src/libFLAC/metadata_iterators.c b/src/libFLAC/metadata_iterators.c
index 0e2edd5..8642c0f 100644
--- a/src/libFLAC/metadata_iterators.c
+++ b/src/libFLAC/metadata_iterators.c
@@ -1618,6 +1618,13 @@
return chain_read_with_callbacks_(chain, handle, callbacks, /*is_ogg=*/true);
}
+typedef enum {
+ LBS_NONE = 0,
+ LBS_SIZE_CHANGED,
+ LBS_BLOCK_ADDED,
+ LBS_BLOCK_REMOVED
+} LastBlockState;
+
FLAC_API FLAC__bool FLAC__metadata_chain_check_if_tempfile_needed(FLAC__Metadata_Chain *chain, FLAC__bool use_padding)
{
/* This does all the same checks that are in chain_prepare_for_write_()
@@ -1625,73 +1632,70 @@
* here if chain_prepare_for_write_() changes.
*/
FLAC__off_t current_length;
- FLAC__Metadata_Node *node;
+ LastBlockState lbs_state = LBS_NONE;
+ unsigned lbs_size = 0;
FLAC__ASSERT(0 != chain);
current_length = chain_calculate_length_(chain);
- for (node = chain->head; node; node = node->next) {
- if(node != chain->tail || !use_padding) {
- if(node->data->length >= (1u << FLAC__STREAM_METADATA_LENGTH_LEN)) {
- if(node->data->type == FLAC__METADATA_TYPE_PADDING) {
- current_length -= node->data->length;
- current_length += (1u << FLAC__STREAM_METADATA_LENGTH_LEN) - 1;
- } else {
- return false /* the return value doesn't matter */;
+ if(use_padding) {
+ const FLAC__Metadata_Node * const node = chain->tail;
+ /* if the metadata shrank and the last block is padding, we just extend the last padding block */
+ if(current_length < chain->initial_length && node->data->type == FLAC__METADATA_TYPE_PADDING) {
+ lbs_state = LBS_SIZE_CHANGED;
+ lbs_size = node->data->length + (chain->initial_length - current_length);
+ }
+ /* if the metadata shrank more than 4 bytes then there's room to add another padding block */
+ else if(current_length + (FLAC__off_t)FLAC__STREAM_METADATA_HEADER_LENGTH <= chain->initial_length) {
+ lbs_state = LBS_BLOCK_ADDED;
+ lbs_size = chain->initial_length - (current_length + (FLAC__off_t)FLAC__STREAM_METADATA_HEADER_LENGTH);
+ }
+ /* if the metadata grew but the last block is padding, try cutting the padding to restore the original length so we don't have to rewrite the whole file */
+ else if(current_length > chain->initial_length) {
+ const FLAC__off_t delta = current_length - chain->initial_length;
+ if(node->data->type == FLAC__METADATA_TYPE_PADDING) {
+ /* if the delta is exactly the size of the last padding block, remove the padding block */
+ if((FLAC__off_t)node->data->length + (FLAC__off_t)FLAC__STREAM_METADATA_HEADER_LENGTH == delta) {
+ lbs_state = LBS_BLOCK_REMOVED;
+ lbs_size = 0;
+ }
+ /* if there is at least 'delta' bytes of padding, trim the padding down */
+ else if((FLAC__off_t)node->data->length >= delta) {
+ lbs_state = LBS_SIZE_CHANGED;
+ lbs_size = node->data->length - delta;
}
}
- } else {
- /* use_padding == true, node == chain->tail */
+ }
+ }
+
+ current_length = 0;
+ /* check sizes of all metadata blocks; reduce padding size if necessary */
+ {
+ const FLAC__Metadata_Node *node;
+ for(node = chain->head; node; node = node->next) {
unsigned block_len = node->data->length;
-
- /* if the metadata shrank and the last block is padding, we just extend the last padding block */
- if(current_length < chain->initial_length && node->data->type == FLAC__METADATA_TYPE_PADDING) {
- const FLAC__off_t delta = chain->initial_length - current_length;
- block_len += delta;
- current_length += delta;
- /* test extended block */
- if(block_len >= (1u << FLAC__STREAM_METADATA_LENGTH_LEN)) {
- current_length -= block_len;
- current_length += (1u << FLAC__STREAM_METADATA_LENGTH_LEN) - 1;
- }
+ if(node == chain->tail) {
+ if(lbs_state == LBS_BLOCK_REMOVED)
+ continue;
+ else if(lbs_state == LBS_SIZE_CHANGED)
+ block_len = lbs_size;
}
- /* if the metadata shrank more than 4 bytes then there's room to add another padding block */
- else if(current_length + (FLAC__off_t)FLAC__STREAM_METADATA_HEADER_LENGTH <= chain->initial_length) {
- /* test current last block */
- if(block_len >= (1u << FLAC__STREAM_METADATA_LENGTH_LEN)) {
- current_length -= block_len;
- current_length += (1u << FLAC__STREAM_METADATA_LENGTH_LEN) - 1;
- }
- block_len = chain->initial_length - (FLAC__STREAM_METADATA_HEADER_LENGTH + current_length);
- current_length += FLAC__STREAM_METADATA_HEADER_LENGTH + block_len;
- /* test added block */
- if(block_len >= (1u << FLAC__STREAM_METADATA_LENGTH_LEN)) {
- current_length -= block_len;
- current_length += (1u << FLAC__STREAM_METADATA_LENGTH_LEN) - 1;
- }
+ if(block_len >= (1u << FLAC__STREAM_METADATA_LENGTH_LEN)) {
+ if(node->data->type == FLAC__METADATA_TYPE_PADDING)
+ block_len = (1u << FLAC__STREAM_METADATA_LENGTH_LEN) - 1;
+ else
+ return false /* the return value doesn't matter */;
}
- /* if the metadata grew but the last block is padding, try cutting the padding to restore the original length so we don't have to rewrite the whole file */
- else if(current_length > chain->initial_length) {
- const FLAC__off_t delta = current_length - chain->initial_length;
- if(node->data->type == FLAC__METADATA_TYPE_PADDING) {
- /* if the delta is exactly the size of the last padding block, remove the padding block */
- if((FLAC__off_t)node->data->length + (FLAC__off_t)FLAC__STREAM_METADATA_HEADER_LENGTH == delta) {
- block_len = 0;
- current_length -= FLAC__STREAM_METADATA_HEADER_LENGTH + node->data->length;
- }
- /* if there is at least 'delta' bytes of padding, trim the padding down */
- else if((FLAC__off_t)node->data->length >= delta) {
- block_len -= delta;
- current_length -= delta;
- /* test shrinked block */
- if(block_len >= (1u << FLAC__STREAM_METADATA_LENGTH_LEN)) {
- current_length -= block_len;
- current_length += (1u << FLAC__STREAM_METADATA_LENGTH_LEN) - 1;
- }
- }
- }
- }
+ current_length += (FLAC__STREAM_METADATA_HEADER_LENGTH + block_len);
+ }
+
+ if(lbs_state == LBS_BLOCK_ADDED) {
+ /* test added padding block */
+ unsigned block_len = lbs_size;
+ if(block_len >= (1u << FLAC__STREAM_METADATA_LENGTH_LEN))
+ block_len = (1u << FLAC__STREAM_METADATA_LENGTH_LEN) - 1;
+ current_length += (FLAC__STREAM_METADATA_HEADER_LENGTH + block_len);
}
}