cpl_compressor.h File Reference

API for compressors and decompressors of binary buffers. More...

#include "cpl_port.h"
#include <stdbool.h>

Go to the source code of this file.

Classes
struct	CPLCompressor
	Compressor/decompressor description. More...

Typedefs
typedef bool(*	CPLCompressionFunc) (const void *input_data, size_t input_size, void **output_data, size_t *output_size, CSLConstList options, void *compressor_user_data)
	Callback of a compressor/decompressor.

Enumerations
enum	CPLCompressorType { CCT_COMPRESSOR , CCT_FILTER }
	Type of compressor. More...

Functions
bool	CPLRegisterCompressor (const CPLCompressor *compressor)
	Register a new compressor.
bool	CPLRegisterDecompressor (const CPLCompressor *decompressor)
	Register a new decompressor.
char **	CPLGetCompressors (void)
	Return the list of registered compressors.
char **	CPLGetDecompressors (void)
	Return the list of registered decompressors.
const CPLCompressor *	CPLGetCompressor (const char *pszId)
	Return a compressor.
const CPLCompressor *	CPLGetDecompressor (const char *pszId)
	Return a decompressor.

Detailed Description

API for compressors and decompressors of binary buffers.

Typedef Documentation

CPLCompressionFunc

typedef bool(* CPLCompressionFunc) (const void *input_data, size_t input_size, void **output_data, size_t *output_size, CSLConstList options, void *compressor_user_data)

Callback of a compressor/decompressor.

For a compressor, input is uncompressed data, and output compressed data. For a decompressor, input is compressed data, and output uncompressed data.

Valid situations for output_data and output_size are:

• output_data != NULL and *output_data != NULL and output_size != NULL and *output_size != 0. The caller provides the output buffer in *output_data and its size in *output_size. In case of successful operation, *output_size will be updated to the actual size. This mode is the one that is always guaranteed to be implemented efficiently. In case of failure due to insufficient space, it will be updated to the size needed (if known), or 0 (if unknown)
• output_data == NULL and output_size != NULL. *output_size will be updated with the minimum size the output buffer should be (if known), or 0 (if unknown).
• output_data != NULL and *output_data == NULL and output_size != NULL. *output_data will be allocated using VSIMalloc(), and should be freed by the caller with VSIFree(). *output_size will be updated to the size of the output buffer.

Parameters

input_data	Input data. Should not be NULL.
input_size	Size of input data, in bytes.
output_data	Pointer to output data.
output_size	Pointer to output size.
options	NULL terminated list of options. Or NULL.
compressor_user_data	User data provided at registration time.

Returns

true in case of success.

Enumeration Type Documentation

CPLCompressorType

enum CPLCompressorType

Type of compressor.

Enumerator
CCT_COMPRESSOR	Compressor.
CCT_FILTER	Filter.

Function Documentation

CPLGetCompressor()

const CPLCompressor * CPLGetCompressor

(

const char *

pszId

)

Return a compressor.

Parameters

pszId

Compressor id. Should NOT be NULL.

Returns

compressor structure, or NULL.

Since

GDAL 3.4

CPLGetCompressors()

char ** CPLGetCompressors

(

void

)

Return the list of registered compressors.

Returns

list of strings. Should be freed with CSLDestroy()

Since

GDAL 3.4

CPLGetDecompressor()

const CPLCompressor * CPLGetDecompressor

(

const char *

pszId

)

Return a decompressor.

Parameters

pszId

Decompressor id. Should NOT be NULL.

Returns

compressor structure, or NULL.

Since

GDAL 3.4

CPLGetDecompressors()

char ** CPLGetDecompressors

(

void

)

Return the list of registered decompressors.

Returns

list of strings. Should be freed with CSLDestroy()

Since

GDAL 3.4

CPLRegisterCompressor()

bool CPLRegisterCompressor

(

const CPLCompressor *

compressor

)

Register a new compressor.

The provided structure is copied. Its pfnFunc and user_data members should remain valid beyond this call however.

Parameters

compressor

Compressor structure. Should not be null.

Returns

true if successful

Since

GDAL 3.4

CPLRegisterDecompressor()

bool CPLRegisterDecompressor

(

const CPLCompressor *

decompressor

)

Register a new decompressor.

The provided structure is copied. Its pfnFunc and user_data members should remain valid beyond this call however.

Parameters

decompressor

Compressor structure. Should not be null.

Returns

true if successful

Since

GDAL 3.4