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

Handling of .xz Index lists. More...

Data Structures

struct  lzma_index_record
 Index Record and its location. More...

Typedefs

typedef struct lzma_index_s lzma_index
 Opaque data type to hold the Index.

Functions

 LZMA_API (uint64_t) lzma_index_memusage(lzma_vli record_count)
 Calculate memory usage for Index with given number of Records.
 LZMA_API (lzma_index *) lzma_index_init(lzma_index *i
 Allocate and initialize a new lzma_index structure.
 LZMA_API (void) lzma_index_end(lzma_index *i
 Deallocate the Index.
 LZMA_API (lzma_ret) lzma_index_append(lzma_index *i
 Add a new Record to an Index.
 LZMA_API (lzma_bool) lzma_index_read(lzma_index *i
 Get the next Record from the Index.

Variables

lzma_allocator *allocator lzma_attr_warn_unused_result
lzma_allocatorallocator
lzma_allocator lzma_vli unpadded_size
lzma_index_recordrecord
lzma_index *lzma_restrict src
const lzma_index *b lzma_attr_pure
lzma_index ** i
uint8_t * out
uint8_t size_t * out_pos
uint8_t size_t size_t out_size
uint64_t * memlimit
uint64_t lzma_allocator const
uint8_t * 
in
uint64_t lzma_allocator const
uint8_t size_t * 
in_pos
uint64_t lzma_allocator const
uint8_t size_t size_t 
in_size

Detailed Description

Handling of .xz Index lists.

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.


Typedef Documentation

typedef struct lzma_index_s lzma_index

Opaque data type to hold the Index.


Function Documentation

LZMA_API ( uint64_t   ) 

Calculate memory usage for Index with given number of Records.

Get the uncompressed size of the Stream.

Get the total size of the file.

Get the total size of the Stream.

Get the total size of the Blocks.

Get the size of the Index field as bytes.

Get the number of Records.

On disk, the size of the Index field depends on both the number of Records stored and how big values the Records store (due to variable-length integer encoding). When the Index is kept in lzma_index structure, the memory usage depends only on the number of Records stored in the Index. The size in RAM is almost always a lot bigger than in encoded form on disk.

This function calculates an approximate amount of memory needed hold the given number of Records in lzma_index structure. This value may vary between liblzma versions if the internal implementation is modified.

If you want to know how much memory an existing lzma_index structure is using, use lzma_index_memusage(lzma_index_count(i)).

This is needed to verify the Backward Size field in the Stream Footer.

This doesn't include the Stream Header, Stream Footer, Stream Padding, or Index fields.

If multiple Indexes have been combined, this works as if the Blocks were in a single Stream.

When no Indexes have been combined with lzma_index_cat(), this function is identical to lzma_index_stream_size(). If multiple Indexes have been combined, this includes also the headers of each separate Stream and the possible Stream Padding fields.

Calculate memory usage for Index with given number of Records.

Calculate rough decoder memory usage of a preset.

This function is a wrapper for lzma_raw_encoder_memusage().

Parameters:
preset Compression preset (level and possible flags)

This function is a wrapper for lzma_raw_decoder_memusage().

Parameters:
preset Compression preset (level and possible flags)

References lzma_filter_encoder::chunk_size, lzma_coder_s::filters, and LZMA_VLI_UNKNOWN.

LZMA_API ( lzma_index  ) 

Allocate and initialize a new lzma_index structure.

Duplicate an Index list.

If i is NULL, a new lzma_index structure is allocated, initialized, and a pointer to it returned. If allocation fails, NULL is returned.

If i is non-NULL, it is reinitialized and the same pointer returned. In this case, return value cannot be NULL or a different pointer than the i that was given as an argument.

Makes an identical copy of the Index. Also the read position is copied.

Returns:
A copy of the Index, or NULL if memory allocation failed.

References lzma_index_s::current, lzma_index_s::group, lzma_index_s::head, lzma_index_group_s::last, lzma_alloc(), lzma_index_group_s::next, lzma_index_group_s::paddings, lzma_index_group_s::prev, lzma_index_s::tail, lzma_index_group_s::uncompressed_sums, and lzma_index_group_s::unpadded_sums.

LZMA_API ( void   ) 

Deallocate the Index.

Free memory allocated for the coder data structures.

Rewind the Index.

If i is NULL, this does nothing.

Rewind the Index so that next call to lzma_index_read() will return the first Record.

LZMA_API ( lzma_ret   ) 

Add a new Record to an Index.

Single-call Index decoder.

Single-call Index encoder.

Initialize Index decoder.

Initialize Index encoder.

Concatenate Indexes of two Streams.

Parameters:
i Pointer to a lzma_index structure
allocator Pointer to lzma_allocator, or NULL to use malloc()
unpadded_size Unpadded Size of a Block. This can be calculated with lzma_block_unpadded_size() after encoding or decoding the Block.
uncompressed_size Uncompressed Size of a Block. This can be taken directly from lzma_block structure after encoding or decoding the Block.

Appending a new Record does not affect the read position.

Returns:
- LZMA_OK
  • LZMA_MEM_ERROR
  • LZMA_DATA_ERROR: Compressed or uncompressed size of the Stream or size of the Index field would grow too big.
  • LZMA_PROG_ERROR
Parameters:
dest Destination Index after which src is appended
src Source Index. The memory allocated for this is either moved to be part of *dest or freed if and only if the function call succeeds, and src will be an invalid pointer.
allocator Custom memory allocator; can be NULL to use malloc() and free().
padding Size of the Stream Padding field between Streams. This must be a multiple of four.
Returns:
- LZMA_OK: Indexes concatenated successfully.
  • LZMA_DATA_ERROR: *dest would grow too big.
  • LZMA_MEM_ERROR
  • LZMA_PROG_ERROR
Parameters:
strm Pointer to properly prepared lzma_stream
i Pointer to lzma_index which should be encoded. The read position will be at the end of the Index after lzma_code() has returned LZMA_STREAM_END.

The only valid action value for lzma_code() is LZMA_RUN.

Returns:
- LZMA_OK: Initialization succeeded, continue with lzma_code().
  • LZMA_MEM_ERROR
  • LZMA_PROG_ERROR
Parameters:
strm Pointer to properly prepared lzma_stream
i Pointer to a pointer that will be made to point to the final decoded Index once lzma_code() has returned LZMA_STREAM_END. That is, lzma_index_decoder() always takes care of allocating a new lzma_index structure, and *i doesn't need to be initialized by the caller.
memlimit How much memory the resulting Index is allowed to require.

The only valid action value for lzma_code() is LZMA_RUN.

Returns:
- LZMA_OK: Initialization succeeded, continue with lzma_code().
  • LZMA_MEM_ERROR
  • LZMA_MEMLIMIT_ERROR
  • LZMA_PROG_ERROR
Note:
The memory usage limit is checked early in the decoding (within the first dozen input bytes or so). The actual memory is allocated later in smaller pieces. If the memory usage limit is modified after decoding a part of the Index already, the new limit may be ignored.
Parameters:
i Index to be encoded. The read position will be at the end of the Index if encoding succeeds, or at unspecified position in case an error occurs.
out Beginning of the output buffer
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:
- LZMA_OK: Encoding was successful.
  • LZMA_BUF_ERROR: Output buffer is too small. Use lzma_index_size() to find out how much output space is needed.
  • LZMA_PROG_ERROR
Note:
This function doesn't take allocator argument since all the internal data is allocated on stack.
Parameters:
i Pointer to a pointer that will be made to point to the final decoded Index if decoding is successful. That is, lzma_index_buffer_decode() always takes care of allocating a new lzma_index structure, and *i doesn't need to be initialized by the caller.
memlimit Pointer to how much memory the resulting Index is allowed to require. The value pointed by this pointer is modified if and only if LZMA_MEMLIMIT_ERROR is returned.
allocator Pointer to lzma_allocator, or NULL to use malloc()
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].
Returns:
- LZMA_OK: Decoding was successful.
  • LZMA_MEM_ERROR
  • LZMA_MEMLIMIT_ERROR: Memory usage limit was reached. The minimum required memlimit value was stored to *memlimit.
  • LZMA_DATA_ERROR
  • LZMA_PROG_ERROR
LZMA_API ( lzma_bool   ) 

Get the next Record from the Index.

Test if the given Filter ID is supported for encoding.

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.

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