archival/libunarchive/check_header_gzip.c

/* vi: set sw=4 ts=4: */
/*
 * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
 */
#include <stdlib.h>
#include <unistd.h>
#include "libbb.h"
#include "unarchive.h" /* for external decl of check_header_gzip */

void check_header_gzip(int src_fd)
{
	union {
		unsigned char raw[8];
		struct {
			unsigned char method;
			unsigned char flags;
			unsigned int mtime;
			unsigned char xtra_flags;
			unsigned char os_flags;
		} formatted;
	} header;

	xread(src_fd, header.raw, 8);

	/* Check the compression method */
	if (header.formatted.method != 8) {
		bb_error_msg_and_die("unknown compression method %d",
						  header.formatted.method);
	}

	if (header.formatted.flags & 0x04) {
		/* bit 2 set: extra field present */
		unsigned char extra_short;

		extra_short = xread_char(src_fd) + (xread_char(src_fd) << 8);
		while (extra_short > 0) {
			/* Ignore extra field */
			xread_char(src_fd);
			extra_short--;
		}
	}

	/* Discard original name if any */
	if (header.formatted.flags & 0x08) {
		/* bit 3 set: original file name present */
		while (xread_char(src_fd) != 0);
	}

	/* Discard file comment if any */
	if (header.formatted.flags & 0x10) {
		/* bit 4 set: file comment present */
		while (xread_char(src_fd) != 0);
	}

	/* Read the header checksum */
	if (header.formatted.flags & 0x02) {
		xread_char(src_fd);
		xread_char(src_fd);
	}

	return;
}
1	niro	532	/* vi: set sw=4 ts=4: */
2			/*
3			* Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
4			*/
5			#include <stdlib.h>
6			#include <unistd.h>
7			#include "libbb.h"
8			#include "unarchive.h" /* for external decl of check_header_gzip */
9
10			void check_header_gzip(int src_fd)
11			{
12			union {
13			unsigned char raw[8];
14			struct {
15			unsigned char method;
16			unsigned char flags;
17			unsigned int mtime;
18			unsigned char xtra_flags;
19			unsigned char os_flags;
20			} formatted;
21			} header;
22
23			xread(src_fd, header.raw, 8);
24
25			/* Check the compression method */
26			if (header.formatted.method != 8) {
27			bb_error_msg_and_die("unknown compression method %d",
28			header.formatted.method);
29			}
30
31			if (header.formatted.flags & 0x04) {
32			/* bit 2 set: extra field present */
33			unsigned char extra_short;
34
35			extra_short = xread_char(src_fd) + (xread_char(src_fd) << 8);
36			while (extra_short > 0) {
37			/* Ignore extra field */
38			xread_char(src_fd);
39			extra_short--;
40			}
41			}
42
43			/* Discard original name if any */
44			if (header.formatted.flags & 0x08) {
45			/* bit 3 set: original file name present */
46			while (xread_char(src_fd) != 0);
47			}
48
49			/* Discard file comment if any */
50			if (header.formatted.flags & 0x10) {
51			/* bit 4 set: file comment present */
52			while (xread_char(src_fd) != 0);
53			}
54
55			/* Read the header checksum */
56			if (header.formatted.flags & 0x02) {
57			xread_char(src_fd);
58			xread_char(src_fd);
59			}
60
61			return;
62			}