/*
 * 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/>.
 */

#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "defs.h"
#include "gzip.h"
#include "ustar.h"

#define OPKG_OPK_USTAR_NUM_BASE_ 8

struct _opkg_opk_ustar_header {
	unsigned char name     [100];
	unsigned char mode       [8];
	unsigned char uid        [8];
	unsigned char gid        [8];
	unsigned char size      [12];
	unsigned char mtime     [12];
	unsigned char chksum     [8];
	unsigned char typeflag   [1];
	unsigned char linkname [100];
	unsigned char magic      [6];
	unsigned char version    [2];
	unsigned char uname     [32];
	unsigned char gname     [32];
	unsigned char devmajor   [8];
	unsigned char devminor   [8];
	unsigned char prefix   [155];
	unsigned char padding   [12];
} __attribute__((__packed__));

struct opkg_opk_ustar {
	struct opkg_opk_gzip *gzip;
	int32_t               data_size_remaining;
	unsigned char         read_record[OPKG_OPK_USTAR_RECORD_SIZE];
};

struct opkg_opk_ustar *
opkg_opk_ustar_init(struct opkg_opk_gzip *gzip)
{
	struct opkg_opk_ustar *ustar;

	ustar = malloc(sizeof(*ustar));
	if (ustar == NULL) {
		return NULL;
	}

	ustar->gzip                = gzip;
	ustar->data_size_remaining = 0;

	return ustar;
}

static int
_opkg_opk_ustar_next(struct opkg_opk_ustar *ustar,
		struct _opkg_opk_ustar_header *header)
{
	static unsigned char  record[OPKG_OPK_USTAR_RECORD_SIZE];
	       char          *size_end;

	switch (opkg_opk_gzip_read(ustar->gzip, header)) {
		case OPKG_OPK_OK:
			break;
		case OPKG_OPK_END:
		case OPKG_OPK_ERROR:
			return OPKG_OPK_ERROR;
	}
	memset(record, 0, OPKG_OPK_USTAR_RECORD_SIZE);
	if (memcmp(header, record, OPKG_OPK_USTAR_RECORD_SIZE) == 0) {
		return OPKG_OPK_END;
	}
	if (memcmp(header->magic, "ustar", strlen("ustar")) != 0) {
		return OPKG_OPK_ERROR;
	}

	ustar->data_size_remaining = strtol((char *) header->size, &size_end,
			OPKG_OPK_USTAR_NUM_BASE_);
	if (*size_end != '\0') {
		return OPKG_OPK_ERROR;
	}

	return OPKG_OPK_OK;
}

int
opkg_opk_ustar_list(struct opkg_opk_ustar *ustar,
		struct opkg_opk_ustar_member *member)
{
	static struct _opkg_opk_ustar_header  header;
	       int                            ret;

	if ((ret =_opkg_opk_ustar_next(ustar, &header)) != OPKG_OPK_OK) {
		return ret;  /* Error or end of archive */
	}

	if (header.prefix[0] != '\0') {
		sprintf(member->name, "%s/%s", header.prefix, header.name);
	} else {
		memcpy(member->name, header.name, sizeof(header.name));
		member->name[sizeof(header.name)] = '\0';
	}

	while (ustar->data_size_remaining > 0) {
		if (opkg_opk_ustar_read(ustar, NULL, NULL) == OPKG_OPK_ERROR) {
			return OPKG_OPK_ERROR;
		}
	}

	return OPKG_OPK_OK;  /* Possibly more members in archive */
}

int
opkg_opk_ustar_seek(struct opkg_opk_ustar *ustar, const char *member)
{
	static struct _opkg_opk_ustar_header  header;
	static unsigned char                  name[OPKG_OPK_USTAR_NAME_MAX_LEN];

	for (;;) {
		if (_opkg_opk_ustar_next(ustar, &header) != OPKG_OPK_OK) {
			return OPKG_OPK_ERROR;  /* Error or end (not found) */
		}

		if (header.prefix[0] != '\0') {
			sprintf((char *) name, "%s/%s", header.prefix,
					header.name);
		} else {
			memcpy(name, header.name, sizeof(header.name));
			name[sizeof(header.name)] = '\0';
		}

		if (strcmp((char *) name, member) == 0) {
			return OPKG_OPK_OK;  /* Member found */
		}

		while (ustar->data_size_remaining > 0) {
			if (opkg_opk_ustar_read(ustar, NULL, NULL) ==
					OPKG_OPK_ERROR) {
				return OPKG_OPK_ERROR;
			}
		}
	}

	return OPKG_OPK_ERROR;  /* Member not found */
}

int
opkg_opk_ustar_read(struct opkg_opk_ustar *ustar, char **buffer, size_t *size)
{
	if (ustar->data_size_remaining == 0) {
		return OPKG_OPK_END;
	}

	switch (opkg_opk_gzip_read(ustar->gzip, ustar->read_record)) {
		case OPKG_OPK_OK:
			break;
		case OPKG_OPK_END:
		case OPKG_OPK_ERROR:
			return OPKG_OPK_ERROR;
	}

	if (buffer != NULL) {
		*buffer = ustar->read_record;
	}
	if (ustar->data_size_remaining >= OPKG_OPK_USTAR_RECORD_SIZE) {
		if (size != NULL) {
			*size = OPKG_OPK_USTAR_RECORD_SIZE;
		}
		ustar->data_size_remaining -= OPKG_OPK_USTAR_RECORD_SIZE;
	} else {
		if (size != NULL) {
			*size = ustar->data_size_remaining;
		}
		ustar->data_size_remaining = 0;
	}
	return OPKG_OPK_OK;
}

void
opkg_opk_ustar_free(struct opkg_opk_ustar *ustar)
{
	free(ustar);
}