iso9660.c

在Linux2.6内核下的udev文件系统的源码

/*
 * volume_id - reads filesystem label and uuid
 *
 * Copyright (C) 2004 Kay Sievers <[e-mail]>
 *
 *	This program 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 version 2 of the License.
 */

#ifndef _GNU_SOURCE
#define _GNU_SOURCE 1
#endif

#ifdef HAVE_CONFIG_H
#  include <config.h>
#endif

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include <ctype.h>

#include "libvolume_id.h"
#include "util.h"

#define ISO_SUPERBLOCK_OFFSET		0x8000
#define ISO_SECTOR_SIZE			0x800
#define ISO_VD_OFFSET			(ISO_SUPERBLOCK_OFFSET + ISO_SECTOR_SIZE)
#define ISO_VD_PRIMARY			0x1
#define ISO_VD_SUPPLEMENTARY		0x2
#define ISO_VD_END			0xff
#define ISO_VD_MAX			16

struct iso_volume_descriptor {
	uint8_t		type;
	uint8_t		id[5];
	uint8_t		version;
	uint8_t		flags;
	uint8_t		system_id[32];
	uint8_t		volume_id[32];
	uint8_t		unused[8];
	uint8_t		space_size[8];
	uint8_t		escape_sequences[8];
} PACKED;

struct high_sierra_volume_descriptor {
	uint8_t		foo[8];
	uint8_t		type;
	uint8_t		id[5];
	uint8_t		version;
} PACKED;

int volume_id_probe_iso9660(struct volume_id *id, uint64_t off, uint64_t size)
{
	uint8_t *buf;
	struct iso_volume_descriptor *is;
	struct high_sierra_volume_descriptor *hs;

	info("probing at offset 0x%llx", (unsigned long long) off);

	buf = volume_id_get_buffer(id, off + ISO_SUPERBLOCK_OFFSET, 0x200);
	if (buf == NULL)
		return -1;

	is = (struct iso_volume_descriptor *) buf;

	if (memcmp(is->id, "CD001", 5) == 0) {
		int vd_offset;
		int i;

		dbg("read label from PVD");
		volume_id_set_label_raw(id, is->volume_id, 32);
		volume_id_set_label_string(id, is->volume_id, 32);

		dbg("looking for SVDs");
		vd_offset = ISO_VD_OFFSET;
		for (i = 0; i < ISO_VD_MAX; i++) {
			uint8_t svd_label[64];

			is = (struct iso_volume_descriptor *) volume_id_get_buffer(id, off + vd_offset, 0x200);
			if (is == NULL || is->type == ISO_VD_END)
				break;
			if (is->type != ISO_VD_SUPPLEMENTARY)
				continue;

			dbg("found SVD at offset 0x%llx", (unsigned long long) (off + vd_offset));
			if (memcmp(is->escape_sequences, "%/@", 3) == 0||
			    memcmp(is->escape_sequences, "%/C", 3) == 0||
			    memcmp(is->escape_sequences, "%/E", 3) == 0) {
				dbg("Joliet extension found");
				volume_id_set_unicode16(svd_label, sizeof(svd_label), is->volume_id, BE, 32);
				if (memcmp(id->label, svd_label, 16) == 0) {
					dbg("SVD label is identical, use the possibly longer PVD one");
					break;
				}

				volume_id_set_label_raw(id, is->volume_id, 32);
				volume_id_set_label_string(id, svd_label, 32);
				strcpy(id->type_version, "Joliet Extension");
				goto found;
			}
			vd_offset += ISO_SECTOR_SIZE;
		}
		goto found;
	}

	hs = (struct high_sierra_volume_descriptor *) buf;

	if (memcmp(hs->id, "CDROM", 5) == 0) {
		strcpy(id->type_version, "High Sierra");
		goto found;
	}

	return -1;

found:
	volume_id_set_usage(id, VOLUME_ID_FILESYSTEM);
	id->type = "iso9660";

	return 0;
}