src/liblzma/api/lzma/check.h File Reference

Integrity checks. More...

Defines

#define LZMA_CHECK_ID_MAX   15
 Maximum valid Check ID.
#define LZMA_CHECK_SIZE_MAX   64
 Maximum size of a Check field.

Enumerations

enum  lzma_check { LZMA_CHECK_NONE = 0, LZMA_CHECK_CRC32 = 1, LZMA_CHECK_CRC64 = 4, LZMA_CHECK_SHA256 = 10 }
 

Type of the integrity check (Check ID).

More...

Functions

 LZMA_API (lzma_bool) lzma_check_is_supported(lzma_check check) lzma_attr_const
 Test if the given Check ID is supported.
 LZMA_API (uint32_t) lzma_check_size(lzma_check check) lzma_attr_const
 Get the size of the Check field with the given Check ID.
 LZMA_API (uint64_t) lzma_crc64(const uint8_t *buf
 Calculate CRC64.
 LZMA_API (lzma_check) lzma_get_check(const lzma_stream *strm)
 Get the type of the integrity check.

Variables

size_t size
size_t uint32_t crc lzma_attr_pure

Detailed Description

Integrity checks.

Author:
Copyright (C) 1999-2006 Igor Pavlov
Copyright (C) 2007 Lasse Collin

This library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version.

This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.


Define Documentation

#define LZMA_CHECK_ID_MAX   15

Maximum valid Check ID.

The .xz file format specification specifies 16 Check IDs (0-15). Some of them are only reserved, that is, no actual Check algorithm has been assigned. When decoding, liblzma still accepts unknown Check IDs for future compatibility. If a valid but unsupported Check ID is detected, liblzma can indicate a warning; see the flags LZMA_TELL_NO_CHECK, LZMA_TELL_UNSUPPORTED_CHECK, and LZMA_TELL_ANY_CHECK in container.h.

#define LZMA_CHECK_SIZE_MAX   64

Maximum size of a Check field.


Enumeration Type Documentation

enum lzma_check

Type of the integrity check (Check ID).

The .xz format supports multiple types of checks that are calculated from the uncompressed data. They very in both speed and ability to detect errors.

Enumerator:
LZMA_CHECK_NONE 

No Check is calculated.

Size of the Check field: 0 bytes

LZMA_CHECK_CRC32 

CRC32 using the polynomial from the IEEE 802.3 standard

Size of the Check field: 4 bytes

LZMA_CHECK_CRC64 

CRC64 using the polynomial from the ECMA-182 standard

Size of the Check field: 8 bytes

LZMA_CHECK_SHA256 

SHA-256

Size of the Check field: 32 bytes


Function Documentation

LZMA_API ( lzma_bool   )  const

Test if the given Check ID is supported.

Set a compression preset to lzma_options_lzma structure.

Test if given compression mode is supported.

Compare if two Index lists are identical.

Locate a Record.

Test if the given Filter ID is supported for decoding.

Returns true if the given Check ID is supported by this liblzma build. Otherwise false is returned. It is safe to call this with a value that is not in the range [0, 15]; in that case the return value is always false.

You can assume that LZMA_CHECK_NONE and LZMA_CHECK_CRC32 are always supported (even if liblzma is built with limited features).

Returns true if the give Filter ID is supported for decoding by this liblzma build. Otherwise false is returned.

When the Index is available, it is possible to do random-access reading with granularity of Block size.

Parameters:
i Pointer to lzma_index structure
record Pointer to a structure to hold the search results
target Uncompressed target offset which the caller would like to locate from the Stream

If the target is smaller than the uncompressed size of the Stream (can be checked with lzma_index_uncompressed_size()):

  • Information about the Record containing the requested uncompressed offset is stored into *record.
  • Read offset will be adjusted so that calling lzma_index_read() can be used to read subsequent Records.
  • This function returns false.

If target is greater than the uncompressed size of the Stream, *record and the read position are not modified, and this function returns true.

Returns:
True if *a and *b are equal, false otherwise.

Returns true if the given compression mode is supported by this liblzma build. Otherwise false is returned. It is safe to call this with a value that isn't listed in lzma_mode enumeration; the return value will be false.

There is no way to list which modes are available in this particular liblzma version and build. It would be useless, because a new compression mode, which the application developer wasn't aware, could require giving additional options to the encoder that the older modes don't need.

0 is the fastest and 9 is the slowest. These match the switches -0 .. -9 of the xz command line tool. In addition, it is possible to bitwise-or flags to the preset. Currently only LZMA_PRESET_EXTREME is supported. The flags are defined in container.h, because the flags are used also with lzma_easy_encoder().

The preset values are subject to changes between liblzma versions.

This function is available only if LZMA1 or LZMA2 encoder has been enabled when building liblzma.

Test if the given Check ID is supported.

Compare if two Index lists are identical.

Locate a Record.

When the Index is available, it is possible to do random-access reading with granularity of Block size.

Parameters:
i Pointer to lzma_index structure
record Pointer to a structure to hold the search results
target Uncompressed target offset which the caller would like to locate from the Stream

If the target is smaller than the uncompressed size of the Stream (can be checked with lzma_index_uncompressed_size()):

  • Information about the Record containing the requested uncompressed offset is stored into *record.
  • Read offset will be adjusted so that calling lzma_index_read() can be used to read subsequent Records.
  • This function returns false.

If target is greater than the uncompressed size of the Stream, *record and the read position are not modified, and this function returns true.

Returns:
True if *a and *b are equal, false otherwise.

Test if the given Check ID is supported.

Set a compression preset to lzma_options_lzma structure.

Test if given compression mode is supported.

Returns true if the given match finder is supported by this liblzma build. Otherwise false is returned. It is safe to call this with a value that isn't listed in lzma_match_finder enumeration; the return value will be false.

There is no way to list which match finders are available in this particular liblzma version and build. It would be useless, because a new match finder, which the application developer wasn't aware, could require giving additional options to the encoder that the older match finders don't need.

Returns true if the given compression mode is supported by this liblzma build. Otherwise false is returned. It is safe to call this with a value that isn't listed in lzma_mode enumeration; the return value will be false.

There is no way to list which modes are available in this particular liblzma version and build. It would be useless, because a new compression mode, which the application developer wasn't aware, could require giving additional options to the encoder that the older modes don't need.

0 is the fastest and 9 is the slowest. These match the switches -0 .. -9 of the xz command line tool. In addition, it is possible to bitwise-or flags to the preset. Currently only LZMA_PRESET_EXTREME is supported. The flags are defined in container.h, because the flags are used also with lzma_easy_encoder().

The preset values are subject to changes between liblzma versions.

This function is available only if LZMA1 or LZMA2 encoder has been enabled when building liblzma.

LZMA_API ( uint32_t   ) 

Get the size of the Check field with the given Check ID.

Get the number of bytes required to encode a VLI.

liblzma version number as an integer

Calculate CRC32.

Although not all Check IDs have a check algorithm associated, the size of every Check is already frozen. This function returns the size (in bytes) of the Check field with the specified Check ID. The values are: { 0, 4, 4, 4, 8, 8, 8, 16, 16, 16, 32, 32, 32, 64, 64, 64 }

If the argument is not in the range [0, 15], UINT32_MAX is returned.

Calculates CRC32 using the polynomial from the IEEE 802.3 standard.

Parameters:
buf Pointer to the input buffer
size Size of the input buffer
crc Previously returned CRC value. This is used to calculate the CRC of a big buffer in smaller chunks. Set to zero when there is no previous value.
Returns:
Updated CRC value, which can be passed to this function again to continue CRC calculation.
LZMA_API ( uint64_t   )  const

Calculate CRC64.

Get the size of the Index field as bytes.

Calculate rough memory requirements for raw encoder.

Calculate Unpadded Size.

Get the memory usage of decoder filter chain.

Calculates CRC64 using the polynomial from the ECMA-182 standard.

This function is used similarly to lzma_crc32(). See its documentation.

References LZMA_VLI_UNKNOWN.

LZMA_API ( lzma_check   )  const

Get the type of the integrity check.

This function can be called only immediatelly after lzma_code() has returned LZMA_NO_CHECK, LZMA_UNSUPPORTED_CHECK, or LZMA_GET_CHECK. Calling this function in any other situation has undefined behavior.


Generated on Tue Oct 6 14:02:22 2009 for XZ Utils by  doxygen 1.6.1