liblzma (XZ Utils): lzma/container.h File Reference

liblzma (XZ Utils) 5.4.7

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container.h File Reference

File formats. More...

## Data Structures
struct | lzma_mt
| Multithreading options. More...

## Macros
#define | LZMA_PRESET_DEFAULT UINT32_C(6)
| Default compression preset.
#define | LZMA_PRESET_LEVEL_MASK UINT32_C(0x1F)
| Mask for preset level.
#define | LZMA_PRESET_EXTREME (UINT32_C(1) << 31)
| Extreme compression preset.
#define | LZMA_TELL_NO_CHECK UINT32_C(0x01)
#define | LZMA_TELL_UNSUPPORTED_CHECK UINT32_C(0x02)
#define | LZMA_TELL_ANY_CHECK UINT32_C(0x04)
#define | LZMA_IGNORE_CHECK UINT32_C(0x10)
#define | LZMA_CONCATENATED UINT32_C(0x08)
#define | LZMA_FAIL_FAST UINT32_C(0x20)

## Functions
uint64_t | lzma_easy_encoder_memusage (uint32_t preset) lzma_nothrow lzma_attr_pure
| Calculate approximate memory usage of easy encoder.
uint64_t | lzma_easy_decoder_memusage (uint32_t preset) lzma_nothrow lzma_attr_pure
| Calculate approximate decoder memory usage of a preset.
lzma_ret | lzma_easy_encoder (lzma_stream *strm, uint32_t preset, lzma_check check) lzma_nothrow lzma_attr_warn_unused_result
| Initialize .xz Stream encoder using a preset number.
lzma_ret | lzma_easy_buffer_encode (uint32_t preset, lzma_check check, const lzma_allocator *allocator, const uint8_t *in, size_t in_size, uint8_t *out, size_t *out_pos, size_t out_size) lzma_nothrow
| Single-call .xz Stream encoding using a preset number.
lzma_ret | lzma_stream_encoder (lzma_stream *strm, const lzma_filter *filters, lzma_check check) lzma_nothrow lzma_attr_warn_unused_result
| Initialize .xz Stream encoder using a custom filter chain.
uint64_t | lzma_stream_encoder_mt_memusage (const lzma_mt *options) lzma_nothrow lzma_attr_pure
| Calculate approximate memory usage of multithreaded .xz encoder.
lzma_ret | lzma_stream_encoder_mt (lzma_stream *strm, const lzma_mt *options) lzma_nothrow lzma_attr_warn_unused_result
| Initialize multithreaded .xz Stream encoder.
lzma_ret | lzma_alone_encoder (lzma_stream *strm, const lzma_options_lzma *options) lzma_nothrow lzma_attr_warn_unused_result
| Initialize .lzma encoder (legacy file format)
size_t | lzma_stream_buffer_bound (size_t uncompressed_size) lzma_nothrow
| Calculate output buffer size for single-call Stream encoder.
lzma_ret | lzma_stream_buffer_encode (lzma_filter *filters, lzma_check check, const lzma_allocator *allocator, const uint8_t *in, size_t in_size, uint8_t *out, size_t *out_pos, size_t out_size) lzma_nothrow lzma_attr_warn_unused_result
| Single-call .xz Stream encoder.
lzma_ret | lzma_microlzma_encoder (lzma_stream *strm, const lzma_options_lzma *options) lzma_nothrow
| MicroLZMA encoder.
lzma_ret | lzma_stream_decoder (lzma_stream *strm, uint64_t memlimit, uint32_t flags) lzma_nothrow lzma_attr_warn_unused_result
| Initialize .xz Stream decoder.
lzma_ret | lzma_stream_decoder_mt (lzma_stream *strm, const lzma_mt *options) lzma_nothrow lzma_attr_warn_unused_result
| Initialize multithreaded .xz Stream decoder.
lzma_ret | lzma_auto_decoder (lzma_stream *strm, uint64_t memlimit, uint32_t flags) lzma_nothrow lzma_attr_warn_unused_result
| Decode .xz, .lzma, and .lz (lzip) files with autodetection.
lzma_ret | lzma_alone_decoder (lzma_stream *strm, uint64_t memlimit) lzma_nothrow lzma_attr_warn_unused_result
| Initialize .lzma decoder (legacy file format)
lzma_ret | lzma_lzip_decoder (lzma_stream *strm, uint64_t memlimit, uint32_t flags) lzma_nothrow lzma_attr_warn_unused_result
| Initialize .lz (lzip) decoder (a foreign file format)
lzma_ret | lzma_stream_buffer_decode (uint64_t *memlimit, uint32_t flags, const lzma_allocator *allocator, const uint8_t *in, size_t *in_pos, size_t in_size, uint8_t *out, size_t *out_pos, size_t out_size) lzma_nothrow lzma_attr_warn_unused_result
| Single-call .xz Stream decoder.
lzma_ret | lzma_microlzma_decoder (lzma_stream *strm, uint64_t comp_size, uint64_t uncomp_size, lzma_bool uncomp_size_is_exact, uint32_t dict_size) lzma_nothrow
| MicroLZMA decoder.

## Detailed Description

File formats.

Note
  Never include this file directly. Use <lzma.h> instead.

## Macro Definition Documentation

## ◆ LZMA_PRESET_DEFAULT

#define LZMA_PRESET_DEFAULT UINT32_C(6)

Default compression preset.

It's not straightforward to recommend a default preset, because in some cases keeping the resource usage relatively low is more important that getting the maximum compression ratio.

## ◆ LZMA_PRESET_LEVEL_MASK

#define LZMA_PRESET_LEVEL_MASK UINT32_C(0x1F)

Mask for preset level.

This is useful only if you need to extract the level from the preset variable. That should be rare.

## ◆ LZMA_PRESET_EXTREME

#define LZMA_PRESET_EXTREME (UINT32_C(1) << 31)

Extreme compression preset.

This flag modifies the preset to make the encoding significantly slower while improving the compression ratio only marginally. This is useful when you don't mind spending time to get as small result as possible.

This flag doesn't affect the memory usage requirements of the decoder (at least not significantly). The memory usage of the encoder may be increased a little but only at the lowest preset levels (0-3).

## ◆ LZMA_TELL_NO_CHECK

#define LZMA_TELL_NO_CHECK UINT32_C(0x01)

This flag makes lzma_code() return LZMA_NO_CHECK if the input stream being decoded has no integrity check. Note that when used with lzma_auto_decoder(), all .lzma files will trigger LZMA_NO_CHECK if LZMA_TELL_NO_CHECK is used.

## ◆ LZMA_TELL_UNSUPPORTED_CHECK

#define LZMA_TELL_UNSUPPORTED_CHECK UINT32_C(0x02)

This flag makes lzma_code() return LZMA_UNSUPPORTED_CHECK if the input stream has an integrity check, but the type of the integrity check is not supported by this liblzma version or build. Such files can still be decoded, but the integrity check cannot be verified.

## ◆ LZMA_TELL_ANY_CHECK

#define LZMA_TELL_ANY_CHECK UINT32_C(0x04)

This flag makes lzma_code() return LZMA_GET_CHECK as soon as the type of the integrity check is known. The type can then be got with lzma_get_check().

## ◆ LZMA_IGNORE_CHECK

#define LZMA_IGNORE_CHECK UINT32_C(0x10)

This flag makes lzma_code() not calculate and verify the integrity check of the compressed data in .xz files. This means that invalid integrity check values won't be detected and LZMA_DATA_ERROR won't be returned in such cases.

This flag only affects the checks of the compressed data itself; the CRC32 values in the .xz headers will still be verified normally.

Don't use this flag unless you know what you are doing. Possible reasons to use this flag:

- Trying to recover data from a corrupt .xz file.
- Speeding up decompression, which matters mostly with SHA-256 or with files that have compressed extremely well. It's recommended to not use this flag for this purpose unless the file integrity is verified externally in some other way.

Support for this flag was added in liblzma 5.1.4beta.

## ◆ LZMA_CONCATENATED

#define LZMA_CONCATENATED UINT32_C(0x08)

This flag enables decoding of concatenated files with file formats that allow concatenating compressed files as is. From the formats currently supported by liblzma, only the .xz and .lz formats allow concatenated files. Concatenated files are not allowed with the legacy .lzma format.

This flag also affects the usage of the `action' argument for lzma_code(). When LZMA_CONCATENATED is used, lzma_code() won't return LZMA_STREAM_END unless LZMA_FINISH is used as `action'. Thus, the application has to set LZMA_FINISH in the same way as it does when encoding.

If LZMA_CONCATENATED is not used, the decoders still accept LZMA_FINISH as `action' for lzma_code(), but the usage of LZMA_FINISH isn't required.

## ◆ LZMA_FAIL_FAST

#define LZMA_FAIL_FAST UINT32_C(0x20)

This flag makes the threaded decoder report errors (like LZMA_DATA_ERROR) as soon as they are detected. This saves time when the application has no interest in a partially decompressed truncated or corrupt file. Note that due to timing randomness, if the same truncated or corrupt input is decompressed multiple times with this flag, a different amount of output may be produced by different runs, and even the error code might vary.

When using LZMA_FAIL_FAST, it is recommended to use LZMA_FINISH to tell the decoder when no more input will be coming because it can help fast detection and reporting of truncated files. Note that in this situation truncated files might be diagnosed with LZMA_DATA_ERROR instead of LZMA_OK or LZMA_BUF_ERROR!

Without this flag the threaded decoder will provide as much output as possible at first and then report the pending error. This default behavior matches the single-threaded decoder and provides repeatable behavior with truncated or corrupt input. There are a few special cases where the behavior can still differ like memory allocation failures (LZMA_MEM_ERROR).

Single-threaded decoders currently ignore this flag.

Support for this flag was added in liblzma 5.3.3alpha. Note that in older versions this flag isn't supported (LZMA_OPTIONS_ERROR) even by functions that ignore this flag in newer liblzma versions.

## Function Documentation

## ◆ lzma_easy_encoder_memusage()

uint64_t lzma_easy_encoder_memusage | ( | uint32_t | preset | ) |
| extern

Calculate approximate memory usage of easy encoder.

This function is a wrapper for lzma_raw_encoder_memusage().

Parameters

  preset | Compression preset (level and possible flags)

Returns
  Number of bytes of memory required for the given preset when encoding or UINT64_MAX on error.

## ◆ lzma_easy_decoder_memusage()

uint64_t lzma_easy_decoder_memusage | ( | uint32_t | preset | ) |
| extern

Calculate approximate decoder memory usage of a preset.

This function is a wrapper for lzma_raw_decoder_memusage().

Parameters

  preset | Compression preset (level and possible flags)

Returns
  Number of bytes of memory required to decompress a file that was compressed using the given preset or UINT64_MAX on error.

## ◆ lzma_easy_encoder()

lzma_ret lzma_easy_encoder | ( | lzma_stream * | strm,
|  | uint32_t | preset,
|  | lzma_check | check
| ) |  |
| extern

Initialize .xz Stream encoder using a preset number.

This function is intended for those who just want to use the basic features of liblzma (that is, most developers out there).

If initialization fails (return value is not LZMA_OK), all the memory allocated for *strm by liblzma is always freed. Thus, there is no need to call lzma_end() after failed initialization.

If initialization succeeds, use lzma_code() to do the actual encoding. Valid values for `action' (the second argument of lzma_code()) are LZMA_RUN, LZMA_SYNC_FLUSH, LZMA_FULL_FLUSH, and LZMA_FINISH. In future, there may be compression levels or flags that don't support LZMA_SYNC_FLUSH.

Parameters

  strm | Pointer to lzma_stream that is at least initialized with LZMA_STREAM_INIT.
  preset | Compression preset to use. A preset consist of level number and zero or more flags. Usually flags aren't used, so preset is simply a number [0, 9] which match the options -0 ... -9 of the xz command line tool. Additional flags can be be set using bitwise-or with the preset level number, e.g. 6 | LZMA_PRESET_EXTREME.
  check | Integrity check type to use. See check.h for available checks. The xz command line tool defaults to LZMA_CHECK_CRC64, which is a good choice if you are unsure. LZMA_CHECK_CRC32 is good too as long as the uncompressed file is not many gigabytes.

Returns
  Possible lzma_ret values:
  - LZMA_OK: Initialization succeeded. Use lzma_code() to encode your data.
  - LZMA_MEM_ERROR: Memory allocation failed.
  - LZMA_OPTIONS_ERROR: The given compression preset is not supported by this build of liblzma.
  - LZMA_UNSUPPORTED_CHECK: The given check type is not supported by this liblzma build.
  - LZMA_PROG_ERROR: One or more of the parameters have values that will never be valid. For example, strm == NULL.

## ◆ lzma_easy_buffer_encode()

lzma_ret lzma_easy_buffer_encode | ( | uint32_t | preset,
|  | lzma_check | check,
|  | const lzma_allocator * | allocator,
|  | const uint8_t * | in,
|  | size_t | in_size,
|  | uint8_t * | out,
|  | size_t * | out_pos,
|  | size_t | out_size
| ) |  |
| extern

Single-call .xz Stream encoding using a preset number.

The maximum required output buffer size can be calculated with lzma_stream_buffer_bound().

Parameters

  | preset | Compression preset to use. See the description in lzma_easy_encoder().
  | check | Type of the integrity check to calculate from uncompressed data.
  | allocator | lzma_allocator for custom allocator functions. Set to NULL to use malloc() and free().
  | in | Beginning of the input buffer
  | in_size | Size of the input buffer
  [out] | out | Beginning of the output buffer
  [out] | out_pos | The next byte will be written to out[*out_pos]. *out_pos is updated only if encoding succeeds.
  | out_size | Size of the out buffer; the first byte into which no data is written to is out[out_size].

Returns
  Possible lzma_ret values:
  - LZMA_OK: Encoding was successful.
  - LZMA_BUF_ERROR: Not enough output buffer space.
  - LZMA_UNSUPPORTED_CHECK
  - LZMA_OPTIONS_ERROR
  - LZMA_MEM_ERROR
  - LZMA_DATA_ERROR
  - LZMA_PROG_ERROR

## ◆ lzma_stream_encoder()

lzma_ret lzma_stream_encoder | ( | lzma_stream * | strm,
|  | const lzma_filter * | filters,
|  | lzma_check | check
| ) |  |
| extern

Initialize .xz Stream encoder using a custom filter chain.

Parameters

  strm | Pointer to lzma_stream that is at least initialized with LZMA_STREAM_INIT.
  filters | Array of filters terminated with .id == LZMA_VLI_UNKNOWN. See filters.h for more information.
  check | Type of the integrity check to calculate from uncompressed data.

Returns
  Possible lzma_ret values:
  - LZMA_OK: Initialization was successful.
  - LZMA_MEM_ERROR
  - LZMA_UNSUPPORTED_CHECK
  - LZMA_OPTIONS_ERROR
  - LZMA_PROG_ERROR

## ◆ lzma_stream_encoder_mt_memusage()

uint64_t lzma_stream_encoder_mt_memusage | ( | const lzma_mt * | options | ) |
| extern

Calculate approximate memory usage of multithreaded .xz encoder.

Since doing the encoding in threaded mode doesn't affect the memory requirements of single-threaded decompressor, you can use lzma_easy_decoder_memusage(options->preset) or lzma_raw_decoder_memusage(options->filters) to calculate the decompressor memory requirements.

Parameters

  options | Compression options

Returns
  Number of bytes of memory required for encoding with the given options. If an error occurs, for example due to unsupported preset or filter chain, UINT64_MAX is returned.

## ◆ lzma_stream_encoder_mt()

lzma_ret lzma_stream_encoder_mt | ( | lzma_stream * | strm,
|  | const lzma_mt * | options
| ) |  |
| extern

Initialize multithreaded .xz Stream encoder.

This provides the functionality of lzma_easy_encoder() and lzma_stream_encoder() as a single function for multithreaded use.

The supported actions for lzma_code() are LZMA_RUN, LZMA_FULL_FLUSH, LZMA_FULL_BARRIER, and LZMA_FINISH. Support for LZMA_SYNC_FLUSH might be added in the future.

Parameters

  strm | Pointer to lzma_stream that is at least initialized with LZMA_STREAM_INIT.
  options | Pointer to multithreaded compression options

Returns
  Possible lzma_ret values:
  - LZMA_OK
  - LZMA_MEM_ERROR
  - LZMA_UNSUPPORTED_CHECK
  - LZMA_OPTIONS_ERROR
  - LZMA_PROG_ERROR

## ◆ lzma_alone_encoder()

lzma_ret lzma_alone_encoder | ( | lzma_stream * | strm,
|  | const lzma_options_lzma * | options
| ) |  |
| extern

Initialize .lzma encoder (legacy file format)

The .lzma format is sometimes called the LZMA_Alone format, which is the reason for the name of this function. The .lzma format supports only the LZMA1 filter. There is no support for integrity checks like CRC32.

Use this function if and only if you need to create files readable by legacy LZMA tools such as LZMA Utils 4.32.x. Moving to the .xz format is strongly recommended.

The valid action values for lzma_code() are LZMA_RUN and LZMA_FINISH. No kind of flushing is supported, because the file format doesn't make it possible.

Parameters

  strm | Pointer to lzma_stream that is at least initialized with LZMA_STREAM_INIT.
  options | Pointer to encoder options

Returns
  Possible lzma_ret values:
  - LZMA_OK
  - LZMA_MEM_ERROR
  - LZMA_OPTIONS_ERROR
  - LZMA_PROG_ERROR

## ◆ lzma_stream_buffer_bound()

size_t lzma_stream_buffer_bound | ( | size_t | uncompressed_size | ) |
| extern

Calculate output buffer size for single-call Stream encoder.

When trying to compress incompressible data, the encoded size will be slightly bigger than the input data. This function calculates how much output buffer space is required to be sure that lzma_stream_buffer_encode() doesn't return LZMA_BUF_ERROR.

The calculated value is not exact, but it is guaranteed to be big enough. The actual maximum output space required may be slightly smaller (up to about 100 bytes). This should not be a problem in practice.

If the calculated maximum size doesn't fit into size_t or would make the Stream grow past LZMA_VLI_MAX (which should never happen in practice), zero is returned to indicate the error.

Note
  The limit calculated by this function applies only to single-call encoding. Multi-call encoding may (and probably will) have larger maximum expansion when encoding incompressible data. Currently there is no function to calculate the maximum expansion of multi-call encoding.

Parameters

  uncompressed_size | Size in bytes of the uncompressed input data

Returns
  Maximum number of bytes needed to store the compressed data.

## ◆ lzma_stream_buffer_encode()

lzma_ret lzma_stream_buffer_encode | ( | lzma_filter * | filters,
|  | lzma_check | check,
|  | const lzma_allocator * | allocator,
|  | const uint8_t * | in,
|  | size_t | in_size,
|  | uint8_t * | out,
|  | size_t * | out_pos,
|  | size_t | out_size
| ) |  |
| extern

Single-call .xz Stream encoder.

Parameters

  | filters | Array of filters terminated with .id == LZMA_VLI_UNKNOWN. See filters.h for more information.
  | check | Type of the integrity check to calculate from uncompressed data.
  | allocator | lzma_allocator for custom allocator functions. Set to NULL to use malloc() and free().
  | in | Beginning of the input buffer
  | in_size | Size of the input buffer
  [out] | out | Beginning of the output buffer
  [out] | out_pos | The next byte will be written to out[*out_pos]. *out_pos is updated only if encoding succeeds.
  | out_size | Size of the out buffer; the first byte into which no data is written to is out[out_size].

Returns
  Possible lzma_ret values:
  - LZMA_OK: Encoding was successful.
  - LZMA_BUF_ERROR: Not enough output buffer space.
  - LZMA_UNSUPPORTED_CHECK
  - LZMA_OPTIONS_ERROR
  - LZMA_MEM_ERROR
  - LZMA_DATA_ERROR
  - LZMA_PROG_ERROR

## ◆ lzma_microlzma_encoder()

lzma_ret lzma_microlzma_encoder | ( | lzma_stream * | strm,
|  | const lzma_options_lzma * | options
| ) |  |
| extern

MicroLZMA encoder.

The MicroLZMA format is a raw LZMA stream whose first byte (always 0x00) has been replaced with bitwise-negation of the LZMA properties (lc/lp/pb). This encoding ensures that the first byte of MicroLZMA stream is never 0x00. There is no end of payload marker and thus the uncompressed size must be stored separately. For the best error detection the dictionary size should be stored separately as well but alternatively one may use the uncompressed size as the dictionary size when decoding.

With the MicroLZMA encoder, lzma_code() behaves slightly unusually. The action argument must be LZMA_FINISH and the return value will never be LZMA_OK. Thus the encoding is always done with a single lzma_code() after the initialization. The benefit of the combination of initialization function and lzma_code() is that memory allocations can be re-used for better performance.

lzma_code() will try to encode as much input as is possible to fit into the given output buffer. If not all input can be encoded, the stream will be finished without encoding all the input. The caller must check both input and output buffer usage after lzma_code() (total_in and total_out in lzma_stream can be convenient). Often lzma_code() can fill the output buffer completely if there is a lot of input, but sometimes a few bytes may remain unused because the next LZMA symbol would require more space.

lzma_stream.avail_out must be at least 6. Otherwise LZMA_PROG_ERROR will be returned.

The LZMA dictionary should be reasonably low to speed up the encoder re-initialization. A good value is bigger than the resulting uncompressed size of most of the output chunks. For example, if output size is 4 KiB, dictionary size of 32 KiB or 64 KiB is good. If the data compresses extremely well, even 128 KiB may be useful.

The MicroLZMA format and this encoder variant were made with the EROFS file system in mind. This format may be convenient in other embedded uses too where many small streams are needed. XZ Embedded includes a decoder for this format.

Parameters

  strm | Pointer to lzma_stream that is at least initialized with LZMA_STREAM_INIT.
  options | Pointer to encoder options

Returns
  Possible lzma_ret values:
  - LZMA_STREAM_END: All good. Check the amounts of input used and output produced. Store the amount of input used (uncompressed size) as it needs to be known to decompress the data.
  - LZMA_OPTIONS_ERROR
  - LZMA_MEM_ERROR
  - LZMA_PROG_ERROR: In addition to the generic reasons for this error code, this may also be returned if there isn't enough output space (6 bytes) to create a valid MicroLZMA stream.

## ◆ lzma_stream_decoder()

lzma_ret lzma_stream_decoder | ( | lzma_stream * | strm,
|  | uint64_t | memlimit,
|  | uint32_t | flags
| ) |  |
| extern

Initialize .xz Stream decoder.

Parameters

  strm | Pointer to lzma_stream that is at least initialized with LZMA_STREAM_INIT.
  memlimit | Memory usage limit as bytes. Use UINT64_MAX to effectively disable the limiter. liblzma 5.2.3 and earlier don't allow 0 here and return LZMA_PROG_ERROR; later versions treat 0 as if 1 had been specified.
  flags | Bitwise-or of zero or more of the decoder flags: LZMA_TELL_NO_CHECK, LZMA_TELL_UNSUPPORTED_CHECK, LZMA_TELL_ANY_CHECK, LZMA_IGNORE_CHECK, LZMA_CONCATENATED, LZMA_FAIL_FAST

Returns
  Possible lzma_ret values:
  - LZMA_OK: Initialization was successful.
  - LZMA_MEM_ERROR: Cannot allocate memory.
  - LZMA_OPTIONS_ERROR: Unsupported flags
  - LZMA_PROG_ERROR

## ◆ lzma_stream_decoder_mt()

lzma_ret lzma_stream_decoder_mt | ( | lzma_stream * | strm,
|  | const lzma_mt * | options
| ) |  |
| extern

Initialize multithreaded .xz Stream decoder.

The decoder can decode multiple Blocks in parallel. This requires that each Block Header contains the Compressed Size and Uncompressed size fields which are added by the multi-threaded encoder, see lzma_stream_encoder_mt().

A Stream with one Block will only utilize one thread. A Stream with multiple Blocks but without size information in Block Headers will be processed in single-threaded mode in the same way as done by lzma_stream_decoder(). Concatenated Streams are processed one Stream at a time; no inter-Stream parallelization is done.

This function behaves like lzma_stream_decoder() when options->threads == 1 and options->memlimit_threading <= 1.

Parameters

  strm | Pointer to lzma_stream that is at least initialized with LZMA_STREAM_INIT.
  options | Pointer to multithreaded compression options

Returns
  Possible lzma_ret values:
  - LZMA_OK: Initialization was successful.
  - LZMA_MEM_ERROR: Cannot allocate memory.
  - LZMA_MEMLIMIT_ERROR: Memory usage limit was reached.
  - LZMA_OPTIONS_ERROR: Unsupported flags.
  - LZMA_PROG_ERROR

## ◆ lzma_auto_decoder()

lzma_ret lzma_auto_decoder | ( | lzma_stream * | strm,
|  | uint64_t | memlimit,
|  | uint32_t | flags
| ) |  |
| extern

Decode .xz, .lzma, and .lz (lzip) files with autodetection.

This decoder autodetects between the .xz, .lzma, and .lz file formats, and calls lzma_stream_decoder(), lzma_alone_decoder(), or lzma_lzip_decoder() once the type of the input file has been detected.

Support for .lz was added in 5.4.0.

If the flag LZMA_CONCATENATED is used and the input is a .lzma file: For historical reasons concatenated .lzma files aren't supported. If there is trailing data after one .lzma stream, lzma_code() will return LZMA_DATA_ERROR. (lzma_alone_decoder() doesn't have such a check as it doesn't support any decoder flags. It will return LZMA_STREAM_END after one .lzma stream.)

Parameters

  strm | Pointer to lzma_stream that is at least initialized with LZMA_STREAM_INIT.
  memlimit | Memory usage limit as bytes. Use UINT64_MAX to effectively disable the limiter. liblzma 5.2.3 and earlier don't allow 0 here and return LZMA_PROG_ERROR; later versions treat 0 as if 1 had been specified.
  flags | Bitwise-or of zero or more of the decoder flags: LZMA_TELL_NO_CHECK, LZMA_TELL_UNSUPPORTED_CHECK, LZMA_TELL_ANY_CHECK, LZMA_IGNORE_CHECK, LZMA_CONCATENATED, LZMA_FAIL_FAST

Returns
  Possible lzma_ret values:
  - LZMA_OK: Initialization was successful.
  - LZMA_MEM_ERROR: Cannot allocate memory.
  - LZMA_OPTIONS_ERROR: Unsupported flags
  - LZMA_PROG_ERROR

## ◆ lzma_alone_decoder()

lzma_ret lzma_alone_decoder | ( | lzma_stream * | strm,
|  | uint64_t | memlimit
| ) |  |
| extern

Initialize .lzma decoder (legacy file format)

Valid `action' arguments to lzma_code() are LZMA_RUN and LZMA_FINISH. There is no need to use LZMA_FINISH, but it's allowed because it may simplify certain types of applications.

Parameters

  strm | Pointer to lzma_stream that is at least initialized with LZMA_STREAM_INIT.
  memlimit | Memory usage limit as bytes. Use UINT64_MAX to effectively disable the limiter. liblzma 5.2.3 and earlier don't allow 0 here and return LZMA_PROG_ERROR; later versions treat 0 as if 1 had been specified.

Returns
  Possible lzma_ret values:
  - LZMA_OK
  - LZMA_MEM_ERROR
  - LZMA_PROG_ERROR

## ◆ lzma_lzip_decoder()

lzma_ret lzma_lzip_decoder | ( | lzma_stream * | strm,
|  | uint64_t | memlimit,
|  | uint32_t | flags
| ) |  |
| extern

Initialize .lz (lzip) decoder (a foreign file format)

This decoder supports the .lz format version 0 and the unextended .lz format version 1:

- Files in the format version 0 were produced by lzip 1.3 and older. Such files aren't common but may be found from file archives as a few source packages were released in this format. People might have old personal files in this format too. Decompression support for the format version 0 was removed in lzip 1.18.
- lzip 1.3 added decompression support for .lz format version 1 files. Compression support was added in lzip 1.4. In lzip 1.6 the .lz format version 1 was extended to support the Sync Flush marker. This extension is not supported by liblzma. lzma_code() will return LZMA_DATA_ERROR at the location of the Sync Flush marker. In practice files with the Sync Flush marker are very rare and thus liblzma can decompress almost all .lz files.

Just like with lzma_stream_decoder() for .xz files, LZMA_CONCATENATED should be used when decompressing normal standalone .lz files.

The .lz format allows putting non-.lz data at the end of a file after at least one valid .lz member. That is, one can append custom data at the end of a .lz file and the decoder is required to ignore it. In liblzma this is relevant only when LZMA_CONCATENATED is used. In that case lzma_code() will return LZMA_STREAM_END and leave lzma_stream.next_in pointing to the first byte of the non-.lz data. An exception to this is if the first 1-3 bytes of the non-.lz data are identical to the .lz magic bytes (0x4C, 0x5A, 0x49, 0x50; "LZIP" in US-ASCII). In such a case the 1-3 bytes will have been ignored by lzma_code(). If one wishes to locate the non-.lz data reliably, one must ensure that the first byte isn't 0x4C. Actually one should ensure that none of the first four bytes of trailing data are equal to the magic bytes because lzip >= 1.20 requires it by default.

Parameters

  strm | Pointer to lzma_stream that is at least initialized with LZMA_STREAM_INIT.
  memlimit | Memory usage limit as bytes. Use UINT64_MAX to effectively disable the limiter.
  flags | Bitwise-or of flags, or zero for no flags. All decoder flags listed above are supported although only LZMA_CONCATENATED and (in very rare cases) LZMA_IGNORE_CHECK are actually useful. LZMA_TELL_NO_CHECK, LZMA_TELL_UNSUPPORTED_CHECK, and LZMA_FAIL_FAST do nothing. LZMA_TELL_ANY_CHECK is supported for consistency only as CRC32 is always used in the .lz format.

Returns
  Possible lzma_ret values:
  - LZMA_OK: Initialization was successful.
  - LZMA_MEM_ERROR: Cannot allocate memory.
  - LZMA_OPTIONS_ERROR: Unsupported flags
  - LZMA_PROG_ERROR

## ◆ lzma_stream_buffer_decode()

lzma_ret lzma_stream_buffer_decode | ( | uint64_t * | memlimit,
|  | uint32_t | flags,
|  | const lzma_allocator * | allocator,
|  | const uint8_t * | in,
|  | size_t * | in_pos,
|  | size_t | in_size,
|  | uint8_t * | out,
|  | size_t * | out_pos,
|  | size_t | out_size
| ) |  |
| extern

Single-call .xz Stream decoder.

Parameters

  | memlimit | Pointer to how much memory the decoder is allowed to allocate. The value pointed by this pointer is modified if and only if LZMA_MEMLIMIT_ERROR is returned.
  | flags | Bitwise-or of zero or more of the decoder flags: LZMA_TELL_NO_CHECK, LZMA_TELL_UNSUPPORTED_CHECK, LZMA_IGNORE_CHECK, LZMA_CONCATENATED, LZMA_FAIL_FAST. Note that LZMA_TELL_ANY_CHECK is not allowed and will return LZMA_PROG_ERROR.
  | allocator | lzma_allocator for custom allocator functions. Set to NULL to use malloc() and free().
  | in | Beginning of the input buffer
  | in_pos | The next byte will be read from in[*in_pos]. *in_pos is updated only if decoding succeeds.
  | in_size | Size of the input buffer; the first byte that won't be read is in[in_size].
  [out] | out | Beginning of the output buffer
  [out] | out_pos | The next byte will be written to out[*out_pos]. *out_pos is updated only if decoding succeeds.
  | out_size | Size of the out buffer; the first byte into which no data is written to is out[out_size].

Returns
  Possible lzma_ret values:
  - LZMA_OK: Decoding was successful.
  - LZMA_FORMAT_ERROR
  - LZMA_OPTIONS_ERROR
  - LZMA_DATA_ERROR
  - LZMA_NO_CHECK: This can be returned only if using the LZMA_TELL_NO_CHECK flag.
  - LZMA_UNSUPPORTED_CHECK: This can be returned only if using the LZMA_TELL_UNSUPPORTED_CHECK flag.
  - LZMA_MEM_ERROR
  - LZMA_MEMLIMIT_ERROR: Memory usage limit was reached. The minimum required memlimit value was stored to *memlimit.
  - LZMA_BUF_ERROR: Output buffer was too small.
  - LZMA_PROG_ERROR

## ◆ lzma_microlzma_decoder()

lzma_ret lzma_microlzma_decoder | ( | lzma_stream * | strm,
|  | uint64_t | comp_size,
|  | uint64_t | uncomp_size,
|  | lzma_bool | uncomp_size_is_exact,
|  | uint32_t | dict_size
| ) |  |
| extern

MicroLZMA decoder.

See lzma_microlzma_encoder() for more information.

The lzma_code() usage with this decoder is completely normal. The special behavior of lzma_code() applies to lzma_microlzma_encoder() only.

Parameters

  strm | Pointer to lzma_stream that is at least initialized with LZMA_STREAM_INIT.
  comp_size | Compressed size of the MicroLZMA stream. The caller must somehow know this exactly.
  uncomp_size | Uncompressed size of the MicroLZMA stream. If the exact uncompressed size isn't known, this can be set to a value that is at most as big as the exact uncompressed size would be, but then the next argument uncomp_size_is_exact must be false.
  uncomp_size_is_exact | If true, uncomp_size must be exactly correct. This will improve error detection at the end of the stream. If the exact uncompressed size isn't known, this must be false. uncomp_size must still be at most as big as the exact uncompressed size is. Setting this to false when the exact size is known will work but error detection at the end of the stream will be weaker.
  dict_size | LZMA dictionary size that was used when compressing the data. It is OK to use a bigger value too but liblzma will then allocate more memory than would actually be required and error detection will be slightly worse. (Note that with the implementation in XZ Embedded it doesn't affect the memory usage if one specifies bigger dictionary than actually required.)

Returns
  Possible lzma_ret values:
  - LZMA_OK
  - LZMA_MEM_ERROR
  - LZMA_OPTIONS_ERROR
  - LZMA_PROG_ERROR