busybox/archival/libunarchive/get_header_tar_gz.c

/* vi: set sw=4 ts=4: */
/*
 * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
 */

#include "libbb.h"
#include "unarchive.h"

char get_header_tar_gz(archive_handle_t *archive_handle)
{
#if BB_MMU
	unsigned char magic[2];
#endif

	/* Can't lseek over pipes */
	archive_handle->seek = seek_by_read;

	/* Check gzip magic only if open_transformer will invoke unpack_gz_stream (MMU case).
	 * Otherwise, it will invoke an external helper "gunzip -cf" (NOMMU case) which will
	 * need the header. */
#if BB_MMU
	xread(archive_handle->src_fd, &magic, 2);
	if ((magic[0] != 0x1f) || (magic[1] != 0x8b)) {
		bb_error_msg_and_die("invalid gzip magic");
	}
#endif

	archive_handle->src_fd = open_transformer(archive_handle->src_fd, unpack_gz_stream, "gunzip");
	archive_handle->offset = 0;
	while (get_header_tar(archive_handle) == EXIT_SUCCESS)
		continue;

	/* Can only do one file at a time */
	return EXIT_FAILURE;
}