/*
 * 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 <http://www.gnu.org/licenses/>.
 */

#ifndef OPKG_OPK_USTAR_H_
#define OPKG_OPK_USTAR_H_

#include <stdint.h>
#include "gzip.h"

#define OPKG_OPK_USTAR_RECORD_SIZE 512
#define OPKG_OPK_USTAR_NAME_SIZE   257  /* prefix[155] + '/' + name[100] + '\0'
                                         */

struct opkg_opk_ustar;

struct opkg_opk_ustar_member {
	char                          name[OPKG_OPK_USTAR_NAME_SIZE];
	uint16_t                      mode;
	uint64_t                      size;
	int64_t                       mtime;
	char                          type;
	char                          linkname[100];
	char                          uname    [32];
	char                          gname    [32];
	struct opkg_opk_ustar_member *next;
};

struct opkg_opk_ustar_seek_name {
	const char                      *name;
	int                              found;
	struct opkg_opk_ustar_seek_name *next;
};

/*
 * Allocates and initializes an archive structure.
 * Parameters:
 * - gzip: Decompressor for archive's gzip stream.
 * Returns:
 * - Allocated archive structure on success.  Free with opkg_opk_ustar_free().
 * - NULL on memory exhaustion.
 */
struct opkg_opk_ustar *
opkg_opk_ustar_init(struct opkg_opk_gzip *gzip);

/*
 * Lists member files one at a time.
 * Parameters:
 * - ustar:  Archive structure.
 * - member: Address in which to store address of allocated member structure.
 *           Free with free().
 * Returns:
 * - OPKG_OPK_OK if a member was listed.  More members may exist.
 * - OPKG_OPK_END if no more members exist.  Parameter "member" is unchanged.
 * - OPKG_OPK_ERROR on decompression error, memory exhaustion, mode or mtime
 *   integer conversion error, or unsupported file type.
 */
int
opkg_opk_ustar_list(struct opkg_opk_ustar *ustar,
		struct opkg_opk_ustar_member **member);

/*
 * Adds a name to a list of names to find with opkg_opk_ustar_seek().  List is
 * dynamically allocated; free with free().
 * Parameters:
 * - head: Address in which to store address of list head.
 * - tail: Address in which to store address of list tail.
 * - name: Name of member file to find.
 * Returns:
 * - OPKG_OPK_OK if the name was added to the list.
 * - OPKG_OPK_ERROR on memory exhaustion.
 */
int
opkg_opk_ustar_add_seek_name(struct opkg_opk_ustar_seek_name **head,
		struct opkg_opk_ustar_seek_name **tail, const char *name);

/*
 * Advances to a named member file.  May be called multiple times until all
 * requested members are found.
 * Parameters:
 * - ustar: Archive structure.
 * - names: Name(s) to find.  Member "found" will be set to "1" on the first
 *   name found.
 * Returns:
 * - OPKG_OPK_OK if a member matching one of the requested names is found but
 *   more names remain to be found.
 * - OPKG_OPK_END if a member matching one of the requested names is found and
 *   no more names remain to be found.
 * - OPKG_OPK_ERROR if no matching member is found or on decompression error, an
 *   invalid header, or unsupported file type.
 */
int
opkg_opk_ustar_seek(struct opkg_opk_ustar *ustar,
		struct opkg_opk_ustar_seek_name *names);

/*
 * Reads up to a record (512 octets) of member file data at a time.
 * Parameters:
 * - ustar:  Archive structure.
 * - buffer: Address in which to store address of data buffer.  May be NULL.  Do
 *   not free.
 * - size:   Address in which to store size of read data.  May be NULL.
 * Returns:
 * - OPKG_OPK_OK if data was read.
 * - OPKG_OPK_END if no more data exists.
 * - OPKG_OPK_ERROR on decompression error or premature end of gzip stream.
 */
int
opkg_opk_ustar_read(struct opkg_opk_ustar *ustar, char **buffer, size_t *size);

/*
 * Frees an archive structure.
 * Parameters:
 * - ustar: Archive structure.
 */
void
opkg_opk_ustar_free(struct opkg_opk_ustar *ustar);

#endif  /* OPKG_OPK_USTAR_H_ */