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libFLAC: More metadata_iterators fixes

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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>
This commit is contained in:
Erik de Castro Lopo
2016-05-22 11:06:29 +10:00
parent 0b9bcebd78
commit fdc1ccf2bd
1 changed files with 61 additions and 57 deletions
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118
src/libFLAC/metadata_iterators.c
View File

@@ -1618,6 +1618,13 @@ FLAC_API FLAC__bool FLAC__metadata_chain_read_ogg_with_callbacks(FLAC__Metadata_
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 @@ FLAC_API FLAC__bool FLAC__metadata_chain_check_if_tempfile_needed(FLAC__Metadata
* 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 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;
}
}
}
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 */;
}
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);
}
}