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xz: Ignore filter chains that are set but never used in --block-list.

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If a filter chain is set but not used in --block-list, it introduced
unexpected behavior such as requiring an unneeded amount of memory to
compress, reducing the number of threads in multi-threaded encoding, and
printing an incorrect amount of memory needed to decompress.

This also renames filters_init_mask => filters_used_mask. A filter is
assumed to be used if it is specified in --filtersX until
coder_set_compression_settings() determines which filters are referenced
in --block-list.
This commit is contained in:
Jia Tan 2023-06-17 20:46:21 +08:00
parent 183819bfd9
commit 8b9913a13d
1 changed files with 48 additions and 18 deletions
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66
src/xz/coder.c
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@ -41,10 +41,13 @@ static lzma_stream strm = LZMA_STREAM_INIT;
/// the --block-list option.
static lzma_filter filters[NUM_FILTER_CHAIN_MAX][LZMA_FILTERS_MAX + 1];
/// Bit mask representing the filters specified through --filtersX. This
/// is needed to verify that an entry in the --block-list option does not
/// try to reference a filter chain that was not initialized.
static uint32_t filters_init_mask = 1;
/// Bit mask representing the filters that are actually used when encoding
/// in the xz format. This is needed since a filter chain could be
/// specified in --filtersX (or the default filter chain), but never used
/// in --block-list. The default filter chain is always assumed to be used,
/// unless --block-list is specified and does not have a block using the
/// default filter chain.
static uint32_t filters_used_mask = 1;
#ifdef HAVE_ENCODERS
/// Track the memory usage for all filter chains (default or --filtersX).
@ -216,12 +219,12 @@ extern void
coder_add_block_filters(const char *str, size_t slot)
{
// Free old filters first, if they were previously allocated.
if (filters_init_mask & (1 << slot))
if (filters_used_mask & (1 << slot))
lzma_filters_free(filters[slot], NULL);
str_to_filters(str, slot, 0);
filters_init_mask |= 1 << slot;
filters_used_mask |= 1 << slot;
}
@ -242,7 +245,7 @@ memlimit_too_small(uint64_t memory_usage)
static void
validate_block_list_filter(const uint32_t filter_num)
{
if (!(filters_init_mask & (1 << filter_num)))
if (!(filters_used_mask & (1 << filter_num)))
message_fatal(_("filter chain %u used by --block-list, but "
"not specified with --filters%u="),
(unsigned)filter_num, (unsigned)filter_num);
@ -267,7 +270,7 @@ filters_memusage_max(const lzma_mt *mt, bool encode)
#endif
for (uint32_t i = 0; i < ARRAY_SIZE(filters); i++) {
if (!(filters_init_mask & (1 << i)))
if (!(filters_used_mask & (1 << i)))
continue;
uint64_t memusage = UINT64_MAX;
@ -321,16 +324,39 @@ coder_set_compression_settings(void)
#endif
#ifdef HAVE_ENCODERS
if (opt_block_list != NULL)
if (opt_block_list != NULL) {
// This mask tracks the filters actually referenced in
// --block-list. It is used to help remove bits from
// filters_used_mask when a filter chain was specified
// but never actually used.
uint32_t filters_ref_mask = 0;
for (uint32_t i = 0; opt_block_list[i].size != 0; i++) {
validate_block_list_filter(
opt_block_list[i].filters_index);
// Mark the current filter as referenced.
filters_ref_mask |= 1 <<
opt_block_list[i].filters_index;
# ifdef MYTHREAD_ENABLED
if (opt_block_list[i].size > max_block_list_size)
max_block_list_size = opt_block_list[i].size;
# endif
}
assert(filters_ref_mask != 0);
// Note: The filters that were initialized but not used do
// not free their options and do not have the filter
// IDs set to LZMA_VLI_UNKNOWN. Filter chains are not
// freed outside of debug mode and the default filter
// chain is never freed.
filters_used_mask = filters_ref_mask;
} else {
// Reset filters used mask in case --block-list is not
// used, but --filtersX is used.
filters_used_mask = 1;
}
#endif
// The default check type is CRC64, but fallback to CRC32
// if CRC64 isn't supported by the copy of liblzma we are
@ -348,7 +374,7 @@ coder_set_compression_settings(void)
// filter chain.
lzma_filter *default_filters = filters[0];
if (filters_count == 0) {
if (filters_count == 0 && filters_used_mask & 1) {
// We are using a preset. This is not a good idea in raw mode
// except when playing around with things. Different versions
// of this software may use different options in presets, and
@ -379,7 +405,9 @@ coder_set_compression_settings(void)
}
// If we are using the .lzma format, allow exactly one filter
// which has to be LZMA1.
// which has to be LZMA1. There is no need to check if the default
// filter chain is being used since it can only be disabled if
// --block-list is used, which is incompatible with FORMAT_LZMA.
if (opt_format == FORMAT_LZMA && (filters_count != 1
|| default_filters[0].id != LZMA_FILTER_LZMA1))
message_fatal(_("The .lzma format supports only "
@ -387,21 +415,23 @@ coder_set_compression_settings(void)
// If we are using the .xz format, make sure that there is no LZMA1
// filter to prevent LZMA_PROG_ERROR.
if (opt_format == FORMAT_XZ)
if (opt_format == FORMAT_XZ && filters_used_mask & 1)
for (size_t i = 0; i < filters_count; ++i)
if (default_filters[i].id == LZMA_FILTER_LZMA1)
message_fatal(_("LZMA1 cannot be used "
"with the .xz format"));
// Print the selected default filter chain.
message_filters_show(V_DEBUG, default_filters);
if (filters_used_mask & 1) {
// Print the selected default filter chain.
message_filters_show(V_DEBUG, default_filters);
}
// The --flush-timeout option requires LZMA_SYNC_FLUSH support
// from the filter chain. Currently the threaded encoder doesn't
// support LZMA_SYNC_FLUSH so single-threaded mode must be used.
if (opt_mode == MODE_COMPRESS && opt_flush_timeout != 0) {
for (uint32_t i = 0; i < ARRAY_SIZE(filters); ++i) {
if (!(filters_init_mask & (1 << i)))
if (!(filters_used_mask & (1 << i)))
continue;
const lzma_filter *fc = filters[i];
@ -451,7 +481,7 @@ coder_set_compression_settings(void)
if (block_size == 0) {
for (uint32_t i = 0; i < ARRAY_SIZE(filters);
i++) {
if (!(filters_init_mask & (1 << i)))
if (!(filters_used_mask & (1 << i)))
continue;
uint64_t size = lzma_mt_block_size(
@ -661,7 +691,7 @@ coder_set_compression_settings(void)
r->filters = NULL;
r->reduce_dict_size = false;
if (!(filters_init_mask & (1 << i)))
if (!(filters_used_mask & (1 << i)))
continue;
for (uint32_t j = 0; filters[i][j].id != LZMA_VLI_UNKNOWN;
@ -1495,7 +1525,7 @@ coder_free(void)
// debug mode and will be freed when the process ends anyway, we
// don't worry about freeing it.
for (uint32_t i = 1; i < ARRAY_SIZE(filters); i++) {
if (filters_init_mask & (1 << i))
if (filters_used_mask & (1 << i))
lzma_filters_free(filters[i], NULL);
}