Viewing file:  index.h (14.08 KB) -rw-r--r--
Select action/file-type:
 (+) |  (+) |  (+) | Code (+) | Session (+) |  (+) | SDB (+) |  (+) |  (+) |  (+) |  (+) |  (+) |
/**
* \file lzma/index.h
* \brief Handling of .xz Index lists
*/
/*
* Author: Lasse Collin
*
* This file has been put into the public domain.
* You can do whatever you want with this file.
*
* See ../lzma.h for information about liblzma as a whole.
*/
#ifndef LZMA_H_INTERNAL
# error Never include this file directly. Use <lzma.h> instead.
#endif
/**
* \brief Opaque data type to hold the Index
*/
typedef struct lzma_index_s lzma_index;
/**
* \brief Index Record and its location
*/
typedef struct {
/**
* \brief Total encoded size of a Block including Block Padding
*
* This value is useful if you need to know the actual size of the
* Block that the Block decoder will read.
*/
lzma_vli total_size;
/**
* \brief Encoded size of a Block excluding Block Padding
*
* This value is stored in the Index. When doing random-access
* reading, you should give this value to the Block decoder along
* with uncompressed_size.
*/
lzma_vli unpadded_size;
/**
* \brief Uncompressed Size of a Block
*/
lzma_vli uncompressed_size;
/**
* \brief Compressed offset in the Stream(s)
*
* This is the offset of the first byte of the Block, that is,
* where you need to seek to decode the Block. The offset
* is relative to the beginning of the Stream, or if there are
* multiple Indexes combined, relative to the beginning of the
* first Stream.
*/
lzma_vli stream_offset;
/**
* \brief Uncompressed offset
*
* When doing random-access reading, it is possible that the target
* offset is not exactly at Block boundary. One will need to compare
* the target offset against uncompressed_offset, and possibly decode
* and throw away some amount of data before reaching the target
* offset.
*/
lzma_vli uncompressed_offset;
} lzma_index_record;
/**
* \brief Calculate memory usage for Index with given 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)).
*/
extern LZMA_API(uint64_t) lzma_index_memusage(lzma_vli record_count)
lzma_nothrow;
/**
* \brief Allocate and initialize a new lzma_index structure
*
* 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.
*/
extern LZMA_API(lzma_index *) lzma_index_init(
lzma_index *i, lzma_allocator *allocator) lzma_nothrow;
/**
* \brief Deallocate the Index
*
* If i is NULL, this does nothing.
*/
extern LZMA_API(void) lzma_index_end(lzma_index *i, lzma_allocator *allocator)
lzma_nothrow;
/**
* \brief Add a new Record to an Index
*
* \param i Pointer to a lzma_index structure
* \param allocator Pointer to lzma_allocator, or NULL to
* use malloc()
* \param unpadded_size Unpadded Size of a Block. This can be
* calculated with lzma_block_unpadded_size()
* after encoding or decoding the Block.
* \param 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.
*
* \return - 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
*/
extern LZMA_API(lzma_ret) lzma_index_append(
lzma_index *i, lzma_allocator *allocator,
lzma_vli unpadded_size, lzma_vli uncompressed_size)
lzma_nothrow lzma_attr_warn_unused_result;
/**
* \brief Get the number of Records
*/
extern LZMA_API(lzma_vli) lzma_index_count(const lzma_index *i)
lzma_nothrow lzma_attr_pure;
/**
* \brief Get the size of the Index field as bytes
*
* This is needed to verify the Backward Size field in the Stream Footer.
*/
extern LZMA_API(lzma_vli) lzma_index_size(const lzma_index *i)
lzma_nothrow lzma_attr_pure;
/**
* \brief Get the total size of the Blocks
*
* This doesn't include the Stream Header, Stream Footer, Stream Padding,
* or Index fields.
*/
extern LZMA_API(lzma_vli) lzma_index_total_size(const lzma_index *i)
lzma_nothrow lzma_attr_pure;
/**
* \brief Get the total size of the Stream
*
* If multiple Indexes have been combined, this works as if the Blocks
* were in a single Stream.
*/
extern LZMA_API(lzma_vli) lzma_index_stream_size(const lzma_index *i)
lzma_nothrow lzma_attr_pure;
/**
* \brief Get the total size of the file
*
* 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.
*/
extern LZMA_API(lzma_vli) lzma_index_file_size(const lzma_index *i)
lzma_nothrow lzma_attr_pure;
/**
* \brief Get the uncompressed size of the Stream
*/
extern LZMA_API(lzma_vli) lzma_index_uncompressed_size(const lzma_index *i)
lzma_nothrow lzma_attr_pure;
/**
* \brief Get the next Record from the Index
*/
extern LZMA_API(lzma_bool) lzma_index_read(
lzma_index *i, lzma_index_record *record)
lzma_nothrow lzma_attr_warn_unused_result;
/**
* \brief Rewind the Index
*
* Rewind the Index so that next call to lzma_index_read() will return the
* first Record.
*/
extern LZMA_API(void) lzma_index_rewind(lzma_index *i) lzma_nothrow;
/**
* \brief Locate a Record
*
* When the Index is available, it is possible to do random-access reading
* with granularity of Block size.
*
* \param i Pointer to lzma_index structure
* \param record Pointer to a structure to hold the search results
* \param 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.
*/
extern LZMA_API(lzma_bool) lzma_index_locate(
lzma_index *i, lzma_index_record *record, lzma_vli target)
lzma_nothrow;
/**
* \brief Concatenate Indexes of two Streams
*
* Concatenating Indexes is useful when doing random-access reading in
* multi-Stream .xz file, or when combining multiple Streams into single
* Stream.
*
* \param dest Destination Index after which src is appended
* \param src Source Index. If this function succeeds, the
* memory allocated for src is freed or moved to
* be part of dest.
* \param allocator Custom memory allocator; can be NULL to use
* malloc() and free().
* \param padding Size of the Stream Padding field between Streams.
* This must be a multiple of four.
*
* \return - LZMA_OK: Indexes concatenated successfully. src is now
* a dangling pointer.
* - LZMA_DATA_ERROR: *dest would grow too big.
* - LZMA_MEM_ERROR
* - LZMA_PROG_ERROR
*/
extern LZMA_API(lzma_ret) lzma_index_cat(lzma_index *lzma_restrict dest,
lzma_index *lzma_restrict src,
lzma_allocator *allocator, lzma_vli padding)
lzma_nothrow lzma_attr_warn_unused_result;
/**
* \brief Duplicate an Index list
*
* Makes an identical copy of the Index. Also the read position is copied.
*
* \return A copy of the Index, or NULL if memory allocation failed.
*/
extern LZMA_API(lzma_index *) lzma_index_dup(
const lzma_index *i, lzma_allocator *allocator)
lzma_nothrow lzma_attr_warn_unused_result;
/**
* \brief Compare if two Index lists are identical
*
* Read positions are not compared.
*
* \return True if *a and *b are equal, false otherwise.
*/
extern LZMA_API(lzma_bool) lzma_index_equal(
const lzma_index *a, const lzma_index *b)
lzma_nothrow lzma_attr_pure;
/**
* \brief Initialize .xz Index encoder
*
* \param strm Pointer to properly prepared lzma_stream
* \param 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.
*
* \return - LZMA_OK: Initialization succeeded, continue with lzma_code().
* - LZMA_MEM_ERROR
* - LZMA_PROG_ERROR
*/
extern LZMA_API(lzma_ret) lzma_index_encoder(lzma_stream *strm, lzma_index *i)
lzma_nothrow lzma_attr_warn_unused_result;
/**
* \brief Initialize .xz Index decoder
*
* \param strm Pointer to properly prepared lzma_stream
* \param 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.
* \param memlimit How much memory the resulting Index is allowed
* to require.
*
* The only valid action value for lzma_code() is LZMA_RUN.
*
* \return - 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 with lzma_memlimit_set() after a part
* of the Index has already been decoded, the new limit may
* get ignored.
*/
extern LZMA_API(lzma_ret) lzma_index_decoder(
lzma_stream *strm, lzma_index **i, uint64_t memlimit)
lzma_nothrow lzma_attr_warn_unused_result;
/**
* \brief Single-call .xz Index encoder
*
* \param 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.
* \param out Beginning of the output buffer
* \param out_pos The next byte will be written to out[*out_pos].
* *out_pos is updated only if encoding succeeds.
* \param out_size Size of the out buffer; the first byte into
* which no data is written to is out[out_size].
*
* \return - 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.
*/
extern LZMA_API(lzma_ret) lzma_index_buffer_encode(lzma_index *i,
uint8_t *out, size_t *out_pos, size_t out_size) lzma_nothrow;
/**
* \brief Single-call .xz Index decoder
*
* \param 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.
* \param 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.
* \param allocator Pointer to lzma_allocator, or NULL to use malloc()
* \param in Beginning of the input buffer
* \param in_pos The next byte will be read from in[*in_pos].
* *in_pos is updated only if decoding succeeds.
* \param in_size Size of the input buffer; the first byte that
* won't be read is in[in_size].
*
* \return - 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
*/
extern LZMA_API(lzma_ret) lzma_index_buffer_decode(lzma_index **i,
uint64_t *memlimit, lzma_allocator *allocator,
const uint8_t *in, size_t *in_pos, size_t in_size)
lzma_nothrow;
|