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/* SPDX-License-Identifier: LGPL-3.0-or-later */
/*
* frag_table.h - This file is part of libsquashfs
*
* Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
*
* This program 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 3 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 Lesser General Public License
* along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
#ifndef SQFS_FRAG_TABLE_H
#define SQFS_FRAG_TABLE_H
#include "sqfs/predef.h"
/**
* @file frag_table.h
*
* @brief Contains declarations for the @ref sqfs_frag_table_t data structure.
*/
/**
* @struct sqfs_frag_table_t
*
* @implements sqfs_object_t
*
* @brief Abstracts reading, writing and management of the fragment table.
*/
#ifdef __cplusplus
extern "C" {
#endif
/**
* @brief Create a fragment table.
*
* @memberof sqfs_frag_table_t
*
* @param flags Currently must be set to 0, otherwise this function fails.
*
* @return A pointer to a new fragment table object on success, NULL on failure.
*/
SQFS_API sqfs_frag_table_t *sqfs_frag_table_create(sqfs_u32 flags);
/**
* @brief Load a fragment table from a SquashFS image.
*
* @memberof sqfs_frag_table_t
*
* @param tbl The fragment table object to load into.
* @param file The file to load the table from.
* @param super The super block that describes the location
* and size of the table.
* @param cmp The compressor to use for uncompressing the table.
*
* @return Zero on success, an @ref E_SQFS_ERROR on failure.
*/
SQFS_API int sqfs_frag_table_read(sqfs_frag_table_t *tbl, sqfs_file_t *file,
const sqfs_super_t *super,
sqfs_compressor_t *cmp);
/**
* @brief Write a fragment table to a SquashFS image.
*
* @memberof sqfs_frag_table_t
*
* The data from the table is compressed and appended to the given file. The
* information about the tables size and location are stored in the given super
* block. Super block flags are updated as well.
*
* @param tbl The fragment table object to store on disk.
* @param file The file to append the table to.
* @param super The super block that should be updated with the location
* and size of the table.
* @param cmp The compressor to use for compressing the table.
*
* @return Zero on success, an @ref E_SQFS_ERROR on failure.
*/
SQFS_API int sqfs_frag_table_write(sqfs_frag_table_t *tbl, sqfs_file_t *file,
sqfs_super_t *super, sqfs_compressor_t *cmp);
/**
* @brief Resolve a fragment block index to its description.
*
* @memberof sqfs_frag_table_t
*
* @param tbl A pointer to the fragmen table object.
* @param index The index into the table.
* @param out Returns the data from the table on success.
*
* @return Zero on success, an @ref E_SQFS_ERROR on failure (e.g. index is
* out of bounds).
*/
SQFS_API int sqfs_frag_table_lookup(sqfs_frag_table_t *tbl, sqfs_u32 index,
sqfs_fragment_t *out);
/**
* @brief Append a table entry to a fragment table.
*
* @memberof sqfs_frag_table_t
*
* @param tbl A pointer to the fragmen table object.
* @param location The absolute on-disk location of the new fragment block.
* @param out The size of the block. Has bit 24 set if compressed.
* @param index If not NULL, returns the allocated table index.
*
* @return Zero on success, an @ref E_SQFS_ERROR on failure (e.g. allocation
* failure).
*/
SQFS_API int sqfs_frag_table_append(sqfs_frag_table_t *tbl, sqfs_u64 location,
sqfs_u32 size, sqfs_u32 *index);
/**
* @brief Modify an existing entry in a fragment table.
*
* @memberof sqfs_frag_table_t
*
* @param tbl A pointer to the fragmen table object.
* @param index The fragment table index.
* @param location The absolute on-disk location of the fragment block.
* @param out The size of the block. Has bit 24 set if compressed.
*
* @return Zero on success, an @ref E_SQFS_ERROR on
* failure (e.g. out of bounds).
*/
SQFS_API int sqfs_frag_table_set(sqfs_frag_table_t *tbl, sqfs_u32 index,
sqfs_u64 location, sqfs_u32 size);
/**
* @brief Get the number of entries stored in a fragment table.
*
* @memberof sqfs_frag_table_t
*
* @param tbl A pointer to the fragmen table object.
*
* @return The number of entries currently stored in the table.
*/
SQFS_API size_t sqfs_frag_table_get_size(sqfs_frag_table_t *tbl);
/**
* @brief Remember a specific tail end chunk within a fragment block.
*
* @memberof sqfs_frag_table_t
*
* This is a convenience function that memorizes a specific tail end packed
* into a fragment block, primarily for looking it up later by hash and size
* using @ref sqfs_frag_table_find_tail_end.
*
* @param tbl A pointer to the fragmen table object.
* @param index An index into the fragment table that identifies the
* fragment block.
* @param offset A byte offset into the actual fragment block itself.
* @param size The size of the tail en inside the fragment block.
* @param hash An arbitrary 32 bit data hash to memorize.
*
* @return Zero on success, an @ref E_SQFS_ERROR on faiure.
*/
SQFS_API int sqfs_frag_table_add_tail_end(sqfs_frag_table_t *tbl,
sqfs_u32 index, sqfs_u32 offset,
sqfs_u32 size, sqfs_u32 hash);
/**
* @brief RFetch a fragment block index and offset by hash and size
*
* @memberof sqfs_frag_table_t
*
* This is a convenience function that can find data chunks previously
* memorized using @ref sqfs_frag_table_add_tail_end.
*
* @param tbl A pointer to the fragmen table object.
* @param hash An arbitrary 32 bit data hash that describes the chunk.
* @param size The size of the chunk to look for.
* @param index Returns an index into the fragment table on success.
* @param offset Returns a byte offset into the fragment block on success.
*
* @return Zero on success, non-zero if the chunk could not be found.
*/
SQFS_API int sqfs_frag_table_find_tail_end(sqfs_frag_table_t *tbl,
sqfs_u32 hash, sqfs_u32 size,
sqfs_u32 *index, sqfs_u32 *offset);
#ifdef __cplusplus
}
#endif
#endif /* SQFS_FRAG_TABLE_H */
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