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/* SPDX-License-Identifier: GPL-3.0-or-later */
#ifndef FRAG_READER_H
#define FRAG_READER_H
#include "squashfs.h"
#include "compress.h"
#include <stdint.h>
#include <stddef.h>
/**
* @struct frag_reader_t
*
* @brief A simple interface for accessing fragments in a SquashFS image
*/
typedef struct {
sqfs_fragment_t *tbl;
size_t num_fragments;
int fd;
compressor_t *cmp;
size_t block_size;
size_t used;
size_t current_index;
uint8_t buffer[];
} frag_reader_t;
/**
* @brief Create a fragment reader
*
* @memberof frag_reader_t
*
* This function internally reads and decodes the fragment table from the
* image and prints error messages to stderr on the way if it fails.
*
* @param super A pointer to the SquashFS super block read from the image
* @param fd A file descriptor of opened the SquashFS image
* @param cmp A pointer to a compressor object to be used for reading meta
* data blocks from the image.
*
* @return A pointer to a new fragment reader or NULL on failure
*/
frag_reader_t *frag_reader_create(sqfs_super_t *super, int fd,
compressor_t *cmp);
/**
* @brief Destroy a fragment reader and free all memory it uses
*
* @memberof frag_reader_t
*
* @param f A pointer to a fragment reader object
*/
void frag_reader_destroy(frag_reader_t *f);
/**
* @brief Read tail-end packed data from a fragment
*
* @memberof frag_reader_t
*
* This function internally takes care of loading and uncompressing the
* fragment block (which is skipped if it has already been loaded earlier).
* It prints error messages to stderr on the way if it fails, including such
* errors as trying to index beyond the fragment table.
*
* @param f A pointer to a fragment reader object
* @param index A fragment index such as stored in an inode
* @param offset A byte offset into the fragment block addressed by the index
* @param buffer A pointer to a destination buffer to copy decoded data to
* @param size The number of bytes to copy into the destination buffer
*
* @return Zero on success, -1 on failure
*/
int frag_reader_read(frag_reader_t *f, size_t index, size_t offset,
void *buffer, size_t size);
#endif /* FRAG_READER_H */
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