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/**
* @file
* API for the header cache compression
*
* @authors
* Copyright (C) 2019-2020 Tino Reichardt <milky-neomutt@mcmilk.de>
* Copyright (C) 2020-2023 Richard Russon <rich@flatcap.org>
*
* @copyright
* This program is free software: you can redistribute it and/or modify it under
* the terms of the GNU General Public License as published by the Free Software
* Foundation, either version 2 of the License, or (at your option) any later
* version.
*
* This program 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 General Public License for more
* details.
*
* You should have received a copy of the GNU General Public License along with
* this program. If not, see <http://www.gnu.org/licenses/>.
*/
/**
* @page lib_compress Compression functions
*
* Data compression
*
* These compression methods are used by the \ref hcache.
*
* ## Interface
*
* Each Compression backend implements the ComprOps API.
*
* ## Source
*
* @subpage compress_compress
*
* | Name | File | Home Page |
* | :--------------------- | :------------------ | :------------------------- |
* | @subpage compress_lz4 | compress/lz4.c | https://github.com/lz4/lz4 |
* | @subpage compress_zlib | compress/zlib.c | https://www.zlib.net/ |
* | @subpage compress_zstd | compress/zstd.c | https://www.zstd.net/ |
*
* Usage with Compression Level set to X:
* - open(level X) -> N times compress() -> close()
* - open(level X) -> N times decompress() -> close()
*/
#ifndef MUTT_COMPRESS_LIB_H
#define MUTT_COMPRESS_LIB_H
#include <stdlib.h>
/// Opaque type for compression data
typedef void ComprHandle;
/**
* @defgroup compress_api Compression API
*
* The Compression API
*/
struct ComprOps
{
const char *name; ///< Compression name
short min_level; ///< Minimum compression level
short max_level; ///< Maximum compression level
/**
* @defgroup compress_open open()
* @ingroup compress_api
*
* open - Open a compression context
* @param[in] level The compression level
* @retval ptr Success, Compression private data
* @retval NULL Otherwise
*/
ComprHandle *(*open)(short level);
/**
* @defgroup compress_compress compress()
* @ingroup compress_api
*
* compress - Compress header cache data
* @param[in] handle Compression handle
* @param[in] data Data to be compressed
* @param[in] dlen Length of the uncompressed data
* @param[out] clen Length of returned compressed data
* @retval ptr Success, pointer to compressed data
* @retval NULL Otherwise
*
* @note This function returns a pointer to data, which will be freed by the
* close() function.
*/
void *(*compress)(ComprHandle *handle, const char *data, size_t dlen, size_t *clen);
/**
* @defgroup compress_decompress decompress()
* @ingroup compress_api
*
* decompress - Decompress header cache data
* @param[in] handle Compression handle
* @param[in] cbuf Data to be decompressed
* @param[in] clen Length of the compressed input data
* @retval ptr Success, pointer to decompressed data
* @retval NULL Otherwise
*
* @note This function returns a pointer to data, which will be freed by the
* close() function.
*/
void *(*decompress)(ComprHandle *handle, const char *cbuf, size_t clen);
/**
* @defgroup compress_close close()
* @ingroup compress_api
*
* close - Close a compression context
* @param[out] ptr Pointer to Compression handle
*
* @note This function will free all allocated resources, which were
* allocated by open(), compress() or decompress()
*/
void (*close)(ComprHandle **ptr);
};
extern const struct ComprOps compr_lz4_ops;
extern const struct ComprOps compr_zlib_ops;
extern const struct ComprOps compr_zstd_ops;
const struct ComprOps *compress_get_ops(const char *compr);
struct Slist * compress_list (void);
#endif /* MUTT_COMPRESS_LIB_H */
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