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DEFINITIONS
This source file includes following definitions.
- coder_set_check
- coder_set_preset
- coder_set_extreme
- coder_add_filter
- lzma_attribute
- coder_set_compression_settings
- is_format_xz
- is_format_lzma
- coder_init
- coder_normal
- coder_passthru
- coder_run
///////////////////////////////////////////////////////////////////////////////
//
/// \file coder.c
/// \brief Compresses or uncompresses a file
//
// Author: Lasse Collin
//
// This file has been put into the public domain.
// You can do whatever you want with this file.
//
///////////////////////////////////////////////////////////////////////////////
#include "private.h"
/// Return value type for coder_init().
enum coder_init_ret {
CODER_INIT_NORMAL,
CODER_INIT_PASSTHRU,
CODER_INIT_ERROR,
};
enum operation_mode opt_mode = MODE_COMPRESS;
enum format_type opt_format = FORMAT_AUTO;
bool opt_auto_adjust = true;
/// Stream used to communicate with liblzma
static lzma_stream strm = LZMA_STREAM_INIT;
/// Filters needed for all encoding all formats, and also decoding in raw data
static lzma_filter filters[LZMA_FILTERS_MAX + 1];
/// Input and output buffers
static io_buf in_buf;
static io_buf out_buf;
/// Number of filters. Zero indicates that we are using a preset.
static size_t filters_count = 0;
/// Number of the preset (0-9)
static size_t preset_number = 6;
/// If a preset is used (no custom filter chain) and preset_extreme is true,
/// a significantly slower compression is used to achieve slightly better
/// compression ratio.
static bool preset_extreme = false;
/// Integrity check type
static lzma_check check;
/// This becomes false if the --check=CHECK option is used.
static bool check_default = true;
extern void
coder_set_check(lzma_check new_check)
{
check = new_check;
check_default = false;
return;
}
extern void
coder_set_preset(size_t new_preset)
{
preset_number = new_preset;
// Setting a preset makes us forget a possibly defined custom
// filter chain.
while (filters_count > 0) {
--filters_count;
free(filters[filters_count].options);
filters[filters_count].options = NULL;
}
return;
}
extern void
coder_set_extreme(void)
{
preset_extreme = true;
return;
}
extern void
coder_add_filter(lzma_vli id, void *options)
{
if (filters_count == LZMA_FILTERS_MAX)
message_fatal(_("Maximum number of filters is four"));
filters[filters_count].id = id;
filters[filters_count].options = options;
++filters_count;
return;
}
static void lzma_attribute((__noreturn__))
memlimit_too_small(uint64_t memory_usage)
{
message(V_ERROR, _("Memory usage limit is too low for the given "
"filter setup."));
message_mem_needed(V_ERROR, memory_usage);
tuklib_exit(E_ERROR, E_ERROR, false);
}
extern void
coder_set_compression_settings(void)
{
// Options for LZMA1 or LZMA2 in case we are using a preset.
static lzma_options_lzma opt_lzma;
if (filters_count == 0) {
// 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
// thus make uncompressing the raw data difficult.
if (opt_format == FORMAT_RAW) {
// The message is shown only if warnings are allowed
// but the exit status isn't changed.
message(V_WARNING, _("Using a preset in raw mode "
"is discouraged."));
message(V_WARNING, _("The exact options of the "
"presets may vary between software "
"versions."));
}
// Get the preset for LZMA1 or LZMA2.
if (preset_extreme)
preset_number |= LZMA_PRESET_EXTREME;
if (lzma_lzma_preset(&opt_lzma, preset_number))
message_bug();
// Use LZMA2 except with --format=lzma we use LZMA1.
filters[0].id = opt_format == FORMAT_LZMA
? LZMA_FILTER_LZMA1 : LZMA_FILTER_LZMA2;
filters[0].options = &opt_lzma;
filters_count = 1;
}
// Terminate the filter options array.
filters[filters_count].id = LZMA_VLI_UNKNOWN;
// If we are using the .lzma format, allow exactly one filter
// which has to be LZMA1.
if (opt_format == FORMAT_LZMA && (filters_count != 1
|| filters[0].id != LZMA_FILTER_LZMA1))
message_fatal(_("The .lzma format supports only "
"the LZMA1 filter"));
// 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)
for (size_t i = 0; i < filters_count; ++i)
if (filters[i].id == LZMA_FILTER_LZMA1)
message_fatal(_("LZMA1 cannot be used "
"with the .xz format"));
// Print the selected filter chain.
message_filters_show(V_DEBUG, filters);
// If using --format=raw, we can be decoding. The memusage function
// also validates the filter chain and the options used for the
// filters.
const uint64_t memory_limit = hardware_memlimit_get(opt_mode);
uint64_t memory_usage;
if (opt_mode == MODE_COMPRESS)
memory_usage = lzma_raw_encoder_memusage(filters);
else
memory_usage = lzma_raw_decoder_memusage(filters);
if (memory_usage == UINT64_MAX)
message_fatal(_("Unsupported filter chain or filter options"));
// Print memory usage info before possible dictionary
// size auto-adjusting.
message_mem_needed(V_DEBUG, memory_usage);
if (opt_mode == MODE_COMPRESS) {
const uint64_t decmem = lzma_raw_decoder_memusage(filters);
if (decmem != UINT64_MAX)
message(V_DEBUG, _("Decompression will need "
"%s MiB of memory."), uint64_to_str(
round_up_to_mib(decmem), 0));
}
if (memory_usage > memory_limit) {
// If --no-auto-adjust was used or we didn't find LZMA1 or
// LZMA2 as the last filter, give an error immediately.
// --format=raw implies --no-auto-adjust.
if (!opt_auto_adjust || opt_format == FORMAT_RAW)
memlimit_too_small(memory_usage);
assert(opt_mode == MODE_COMPRESS);
// Look for the last filter if it is LZMA2 or LZMA1, so
// we can make it use less RAM. With other filters we don't
// know what to do.
size_t i = 0;
while (filters[i].id != LZMA_FILTER_LZMA2
&& filters[i].id != LZMA_FILTER_LZMA1) {
if (filters[i].id == LZMA_VLI_UNKNOWN)
memlimit_too_small(memory_usage);
++i;
}
// Decrease the dictionary size until we meet the memory
// usage limit. First round down to full mebibytes.
lzma_options_lzma *opt = filters[i].options;
const uint32_t orig_dict_size = opt->dict_size;
opt->dict_size &= ~((UINT32_C(1) << 20) - 1);
while (true) {
// If it is below 1 MiB, auto-adjusting failed. We
// could be more sophisticated and scale it down even
// more, but let's see if many complain about this
// version.
//
// FIXME: Displays the scaled memory usage instead
// of the original.
if (opt->dict_size < (UINT32_C(1) << 20))
memlimit_too_small(memory_usage);
memory_usage = lzma_raw_encoder_memusage(filters);
if (memory_usage == UINT64_MAX)
message_bug();
// Accept it if it is low enough.
if (memory_usage <= memory_limit)
break;
// Otherwise 1 MiB down and try again. I hope this
// isn't too slow method for cases where the original
// dict_size is very big.
opt->dict_size -= UINT32_C(1) << 20;
}
// Tell the user that we decreased the dictionary size.
message(V_WARNING, _("Adjusted LZMA%c dictionary size "
"from %s MiB to %s MiB to not exceed "
"the memory usage limit of %s MiB"),
filters[i].id == LZMA_FILTER_LZMA2
? '2' : '1',
uint64_to_str(orig_dict_size >> 20, 0),
uint64_to_str(opt->dict_size >> 20, 1),
uint64_to_str(round_up_to_mib(
memory_limit), 2));
}
/*
// Limit the number of worker threads so that memory usage
// limit isn't exceeded.
assert(memory_usage > 0);
size_t thread_limit = memory_limit / memory_usage;
if (thread_limit == 0)
thread_limit = 1;
if (opt_threads > thread_limit)
opt_threads = thread_limit;
*/
if (check_default) {
// The default check type is CRC64, but fallback to CRC32
// if CRC64 isn't supported by the copy of liblzma we are
// using. CRC32 is always supported.
check = LZMA_CHECK_CRC64;
if (!lzma_check_is_supported(check))
check = LZMA_CHECK_CRC32;
}
return;
}
/// Return true if the data in in_buf seems to be in the .xz format.
static bool
is_format_xz(void)
{
// Specify the magic as hex to be compatible with EBCDIC systems.
static const uint8_t magic[6] = { 0xFD, 0x37, 0x7A, 0x58, 0x5A, 0x00 };
return strm.avail_in >= sizeof(magic)
&& memcmp(in_buf.u8, magic, sizeof(magic)) == 0;
}
/// Return true if the data in in_buf seems to be in the .lzma format.
static bool
is_format_lzma(void)
{
// The .lzma header is 13 bytes.
if (strm.avail_in < 13)
return false;
// Decode the LZMA1 properties.
lzma_filter filter = { .id = LZMA_FILTER_LZMA1 };
if (lzma_properties_decode(&filter, NULL, in_buf.u8, 5) != LZMA_OK)
return false;
// A hack to ditch tons of false positives: We allow only dictionary
// sizes that are 2^n or 2^n + 2^(n-1) or UINT32_MAX. LZMA_Alone
// created only files with 2^n, but accepts any dictionary size.
// If someone complains, this will be reconsidered.
lzma_options_lzma *opt = filter.options;
const uint32_t dict_size = opt->dict_size;
free(opt);
if (dict_size != UINT32_MAX) {
uint32_t d = dict_size - 1;
d |= d >> 2;
d |= d >> 3;
d |= d >> 4;
d |= d >> 8;
d |= d >> 16;
++d;
if (d != dict_size || dict_size == 0)
return false;
}
// Another hack to ditch false positives: Assume that if the
// uncompressed size is known, it must be less than 256 GiB.
// Again, if someone complains, this will be reconsidered.
uint64_t uncompressed_size = 0;
for (size_t i = 0; i < 8; ++i)
uncompressed_size |= (uint64_t)(in_buf.u8[5 + i]) << (i * 8);
if (uncompressed_size != UINT64_MAX
&& uncompressed_size > (UINT64_C(1) << 38))
return false;
return true;
}
/// Detect the input file type (for now, this done only when decompressing),
/// and initialize an appropriate coder. Return value indicates if a normal
/// liblzma-based coder was initialized (CODER_INIT_NORMAL), if passthru
/// mode should be used (CODER_INIT_PASSTHRU), or if an error occurred
/// (CODER_INIT_ERROR).
static enum coder_init_ret
coder_init(file_pair *pair)
{
lzma_ret ret = LZMA_PROG_ERROR;
if (opt_mode == MODE_COMPRESS) {
switch (opt_format) {
case FORMAT_AUTO:
// args.c ensures this.
assert(0);
break;
case FORMAT_XZ:
ret = lzma_stream_encoder(&strm, filters, check);
break;
case FORMAT_LZMA:
ret = lzma_alone_encoder(&strm, filters[0].options);
break;
case FORMAT_RAW:
ret = lzma_raw_encoder(&strm, filters);
break;
}
} else {
const uint32_t flags = LZMA_TELL_UNSUPPORTED_CHECK
| LZMA_CONCATENATED;
// We abuse FORMAT_AUTO to indicate unknown file format,
// for which we may consider passthru mode.
enum format_type init_format = FORMAT_AUTO;
switch (opt_format) {
case FORMAT_AUTO:
if (is_format_xz())
init_format = FORMAT_XZ;
else if (is_format_lzma())
init_format = FORMAT_LZMA;
break;
case FORMAT_XZ:
if (is_format_xz())
init_format = FORMAT_XZ;
break;
case FORMAT_LZMA:
if (is_format_lzma())
init_format = FORMAT_LZMA;
break;
case FORMAT_RAW:
init_format = FORMAT_RAW;
break;
}
switch (init_format) {
case FORMAT_AUTO:
// Uknown file format. If --decompress --stdout
// --force have been given, then we copy the input
// as is to stdout. Checking for MODE_DECOMPRESS
// is needed, because we don't want to do use
// passthru mode with --test.
if (opt_mode == MODE_DECOMPRESS
&& opt_stdout && opt_force)
return CODER_INIT_PASSTHRU;
ret = LZMA_FORMAT_ERROR;
break;
case FORMAT_XZ:
ret = lzma_stream_decoder(&strm,
hardware_memlimit_get(
MODE_DECOMPRESS), flags);
break;
case FORMAT_LZMA:
ret = lzma_alone_decoder(&strm,
hardware_memlimit_get(
MODE_DECOMPRESS));
break;
case FORMAT_RAW:
// Memory usage has already been checked in
// coder_set_compression_settings().
ret = lzma_raw_decoder(&strm, filters);
break;
}
// Try to decode the headers. This will catch too low
// memory usage limit in case it happens in the first
// Block of the first Stream, which is where it very
// probably will happen if it is going to happen.
if (ret == LZMA_OK && init_format != FORMAT_RAW) {
strm.next_out = NULL;
strm.avail_out = 0;
ret = lzma_code(&strm, LZMA_RUN);
}
}
if (ret != LZMA_OK) {
message_error("%s: %s", pair->src_name, message_strm(ret));
if (ret == LZMA_MEMLIMIT_ERROR)
message_mem_needed(V_ERROR, lzma_memusage(&strm));
return CODER_INIT_ERROR;
}
return CODER_INIT_NORMAL;
}
/// Compress or decompress using liblzma.
static bool
coder_normal(file_pair *pair)
{
// Encoder needs to know when we have given all the input to it.
// The decoders need to know it too when we are using
// LZMA_CONCATENATED. We need to check for src_eof here, because
// the first input chunk has been already read, and that may
// have been the only chunk we will read.
lzma_action action = pair->src_eof ? LZMA_FINISH : LZMA_RUN;
lzma_ret ret;
// Assume that something goes wrong.
bool success = false;
strm.next_out = out_buf.u8;
strm.avail_out = IO_BUFFER_SIZE;
while (!user_abort) {
// Fill the input buffer if it is empty and we haven't reached
// end of file yet.
if (strm.avail_in == 0 && !pair->src_eof) {
strm.next_in = in_buf.u8;
strm.avail_in = io_read(
pair, &in_buf, IO_BUFFER_SIZE);
if (strm.avail_in == SIZE_MAX)
break;
if (pair->src_eof)
action = LZMA_FINISH;
}
// Let liblzma do the actual work.
ret = lzma_code(&strm, action);
// Write out if the output buffer became full.
if (strm.avail_out == 0) {
if (opt_mode != MODE_TEST && io_write(pair, &out_buf,
IO_BUFFER_SIZE - strm.avail_out))
break;
strm.next_out = out_buf.u8;
strm.avail_out = IO_BUFFER_SIZE;
}
if (ret != LZMA_OK) {
// Determine if the return value indicates that we
// won't continue coding.
const bool stop = ret != LZMA_NO_CHECK
&& ret != LZMA_UNSUPPORTED_CHECK;
if (stop) {
// Write the remaining bytes even if something
// went wrong, because that way the user gets
// as much data as possible, which can be good
// when trying to get at least some useful
// data out of damaged files.
if (opt_mode != MODE_TEST && io_write(pair,
&out_buf, IO_BUFFER_SIZE
- strm.avail_out))
break;
}
if (ret == LZMA_STREAM_END) {
// Check that there is no trailing garbage.
// This is needed for LZMA_Alone and raw
// streams.
if (strm.avail_in == 0 && !pair->src_eof) {
// Try reading one more byte.
// Hopefully we don't get any more
// input, and thus pair->src_eof
// becomes true.
strm.avail_in = io_read(
pair, &in_buf, 1);
if (strm.avail_in == SIZE_MAX)
break;
assert(strm.avail_in == 0
|| strm.avail_in == 1);
}
if (strm.avail_in == 0) {
assert(pair->src_eof);
success = true;
break;
}
// We hadn't reached the end of the file.
ret = LZMA_DATA_ERROR;
assert(stop);
}
// If we get here and stop is true, something went
// wrong and we print an error. Otherwise it's just
// a warning and coding can continue.
if (stop) {
message_error("%s: %s", pair->src_name,
message_strm(ret));
} else {
message_warning("%s: %s", pair->src_name,
message_strm(ret));
// When compressing, all possible errors set
// stop to true.
assert(opt_mode != MODE_COMPRESS);
}
if (ret == LZMA_MEMLIMIT_ERROR) {
// Display how much memory it would have
// actually needed.
message_mem_needed(V_ERROR,
lzma_memusage(&strm));
}
if (stop)
break;
}
// Show progress information under certain conditions.
message_progress_update();
}
return success;
}
/// Copy from input file to output file without processing the data in any
/// way. This is used only when trying to decompress unrecognized files
/// with --decompress --stdout --force, so the output is always stdout.
static bool
coder_passthru(file_pair *pair)
{
while (strm.avail_in != 0) {
if (user_abort)
return false;
if (io_write(pair, &in_buf, strm.avail_in))
return false;
strm.total_in += strm.avail_in;
strm.total_out = strm.total_in;
message_progress_update();
strm.avail_in = io_read(pair, &in_buf, IO_BUFFER_SIZE);
if (strm.avail_in == SIZE_MAX)
return false;
}
return true;
}
extern void
coder_run(const char *filename)
{
// Set and possibly print the filename for the progress message.
message_filename(filename);
// Try to open the input file.
file_pair *pair = io_open_src(filename);
if (pair == NULL)
return;
// Assume that something goes wrong.
bool success = false;
// Read the first chunk of input data. This is needed to detect
// the input file type (for now, only for decompression).
strm.next_in = in_buf.u8;
strm.avail_in = io_read(pair, &in_buf, IO_BUFFER_SIZE);
if (strm.avail_in != SIZE_MAX) {
// Initialize the coder. This will detect the file format
// and, in decompression or testing mode, check the memory
// usage of the first Block too. This way we don't try to
// open the destination file if we see that coding wouldn't
// work at all anyway. This also avoids deleting the old
// "target" file if --force was used.
const enum coder_init_ret init_ret = coder_init(pair);
if (init_ret != CODER_INIT_ERROR && !user_abort) {
// Don't open the destination file when --test
// is used.
if (opt_mode == MODE_TEST || !io_open_dest(pair)) {
// Initialize the progress indicator.
const uint64_t in_size
= pair->src_st.st_size <= 0
? 0 : pair->src_st.st_size;
message_progress_start(&strm, in_size);
// Do the actual coding or passthru.
if (init_ret == CODER_INIT_NORMAL)
success = coder_normal(pair);
else
success = coder_passthru(pair);
message_progress_end(success);
}
}
}
// Close the file pair. It needs to know if coding was successful to
// know if the source or target file should be unlinked.
io_close(pair, success);
return;
}