/*-

 * Copyright (c) 2012 Michihiro NAKAJIMA

 * All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 * 1. Redistributions of source code must retain the above copyright

 *    notice, this list of conditions and the following disclaimer.

 * 2. Redistributions in binary form must reproduce the above copyright

 *    notice, this list of conditions and the following disclaimer in the

 *    documentation and/or other materials provided with the distribution.

 *

 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``AS IS'' AND ANY EXPRESS OR

 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES

 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.

 * IN NO EVENT SHALL THE AUTHOR(S) BE LIABLE FOR ANY DIRECT, INDIRECT,

 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT

 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,

 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY

 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF

 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 */

#include "archive_platform.h"

__FBSDID("$FreeBSD$");

#ifdef HAVE_ERRNO_H

#include <errno.h>

#endif

#ifdef HAVE_STDLIB_H

#include <stdlib.h>

#endif

#ifdef HAVE_STRING_H

#include <string.h>

#endif

#ifdef HAVE_UNISTD_H

#include <unistd.h>

#endif

#include "archive.h"

#include "archive_private.h"

#include "archive_read_private.h"

static const unsigned char grzip_magic[] = {

	0x47, 0x52, 0x5a, 0x69, 0x70, 0x49, 0x49, 0x00,

	0x02, 0x04, 0x3a, 0x29 };

static int	grzip_bidder_bid(struct archive_read_filter_bidder *,

		    struct archive_read_filter *);

static int	grzip_bidder_init(struct archive_read_filter *);

static int

grzip_reader_free(struct archive_read_filter_bidder *self)

{

	(void)self; /* UNUSED */

	return (ARCHIVE_OK);

}

int

archive_read_support_filter_grzip(struct archive *_a)

{

	struct archive_read *a = (struct archive_read *)_a;

	struct archive_read_filter_bidder *reader;

	archive_check_magic(_a, ARCHIVE_READ_MAGIC,

	    ARCHIVE_STATE_NEW, "archive_read_support_filter_grzip");

	if (__archive_read_get_bidder(a, &reader) != ARCHIVE_OK)

		return (ARCHIVE_FATAL);

	reader->data = NULL;

	reader->bid = grzip_bidder_bid;

	reader->init = grzip_bidder_init;

	reader->options = NULL;

	reader->free = grzip_reader_free;

	/* This filter always uses an external program. */

	archive_set_error(_a, ARCHIVE_ERRNO_MISC,

	    "Using external grzip program for grzip decompression");

	return (ARCHIVE_WARN);

}

/*

 * Bidder just verifies the header and returns the number of verified bits.

 */

static int

grzip_bidder_bid(struct archive_read_filter_bidder *self,

    struct archive_read_filter *filter)

{

	const unsigned char *p;

	ssize_t avail;

	(void)self; /* UNUSED */

	p = __archive_read_filter_ahead(filter, sizeof(grzip_magic), &avail);

	if (p == NULL || avail == 0)

		return (0);

	if (memcmp(p, grzip_magic, sizeof(grzip_magic)))

		return (0);

	return (sizeof(grzip_magic) * 8);

}

static int

grzip_bidder_init(struct archive_read_filter *self)

{

	int r;

	r = __archive_read_program(self, "grzip -d");

	/* Note: We set the format here even if __archive_read_program()

	 * above fails.  We do, after all, know what the format is

	 * even if we weren't able to read it. */

	self->code = ARCHIVE_FILTER_GRZIP;

	self->name = "grzip";

	return (r);

}