/*
 * Copyright (C) 2023  Patrick McDermott
 *
 * This file is part of opkg-opk.
 *
 * opkg-opk 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 3 of the License, or
 * (at your option) any later version.
 *
 * opkg-opk 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 opkg-opk.  If not, see <https://www.gnu.org/licenses/>.
 */

#ifndef OPKG_OPK_GZIP_H_
#define OPKG_OPK_GZIP_H_

#include <stdio.h>

struct opkg_opk_gzip;

typedef int (opkg_opk_gzip_read_func)(void *, char **, size_t *);

/*
 * Allocates and initializes a decompression structure.
 * Parameters:
 * - read:      Function to read compressed data.  Parameter 1 is user_data,
 *              parameter 2 is an address in which the read function should
 *              store an address to compressed data, and parameter 3 is an
 *              address in which the read function should store the size of read
 *              compressed data.  Should return OPKG_OPK_OK if data is read,
 *              OPKG_OPK_END if no more data is available (end of file or
 *              archive), or OPKG_OPK_ERROR on error.
 * - user_data: Passed to read function.
 * Returns:
 * - Allocated decompression structure on success.  Free with
 *   opkg_opk_gzip_free().
 * - NULL on memory exhaustion.
 */
struct opkg_opk_gzip *
opkg_opk_gzip_init_read(opkg_opk_gzip_read_func *read_func, void *user_data);

struct opkg_opk_gzip *
opkg_opk_gzip_init_write(FILE *write_fp);

/*
 * Reads and decompresses data to output the next record (512 octets).
 * Parameters:
 * - gzip:   Decompression structure.
 * - record: Address in which to store decompressed record.
 * Returns:
 * - OPKG_OPK_OK if a record is read and decompressed.
 * - OPKG_OPK_END if the end of the gzip stream is reached.
 * - OPKG_OPK_ERROR if the read function returned an error, the compressed input
 *   data or gzip stream end prematurely, or zlib returns an error.
 */
int
opkg_opk_gzip_read(struct opkg_opk_gzip *gzip, void *record);

int
opkg_opk_gzip_write(struct opkg_opk_gzip *gzip, void *record, size_t size);

size_t
opkg_opk_gzip_written(struct opkg_opk_gzip *gzip) __attribute__((__pure__));

int
opkg_opk_gzip_finish_write(struct opkg_opk_gzip *gzip);

/*
 * Frees a decompression structure.
 * Parameters:
 * - gzip: Decompression structure.
 */
int
opkg_opk_gzip_free(struct opkg_opk_gzip *gzip);

#endif  /* OPKG_OPK_GZIP_H_ */