eltorito.c

创建一个符合iso-9660标准的iso文件系统

fill_boot_desc(boot_desc_entry, boot_entry)
	struct eltorito_defaultboot_entry *boot_desc_entry;
	struct eltorito_boot_entry_info *boot_entry;
{
	struct directory_entry *de;	/* Boot file */
	int             bootmbr;
	int             i;
	int             nsectors;
	int             geosec;

	if (!boot_desc_entry || !boot_entry)
		return;

	/* now adjust boot catalog lets find boot image first */
	de = search_tree_file(root, boot_entry->boot_image);
	if (!de) {
#ifdef	USE_LIBSCHILY
		comerrno(EX_BAD, "Uh oh, I cant find the boot image '%s' !\n",
							boot_entry->boot_image);
#else
		fprintf(stderr, "Uh oh, I cant find the boot image '%s' !\n",
							boot_entry->boot_image);
		exit(1);
#endif
	}
	/* now make the initial/default entry for boot catalog */
	memset(boot_desc_entry, 0, sizeof(*boot_desc_entry));
	boot_desc_entry->boot_id[0] = (char) boot_entry->not_bootable ?
				EL_TORITO_NOT_BOOTABLE : EL_TORITO_BOOTABLE;

	/* use default BIOS loadpnt */
	set_721(boot_desc_entry->loadseg, boot_entry->load_addr);

	/*
	 * figure out size of boot image in 512-byte sectors.
	 * However, round up to the nearest integral CD (2048-byte) sector.
	 * This is only used for no-emulation booting.
	 */
	nsectors = boot_entry->load_size ? boot_entry->load_size : ((de->size + 2047) / 2048) * 4;
	fprintf(stderr, "\nSize of boot image is %d sectors -> ", nsectors);

	if (boot_entry->hard_disk_boot) {
		/* sanity test hard disk boot image */
		boot_desc_entry->boot_media[0] = EL_TORITO_MEDIA_HD;
		fprintf(stderr, "Emulating a hard disk\n");

		/* read MBR */
		bootmbr = open(de->whole_name, O_RDONLY | O_BINARY);
		if (bootmbr == -1) {
#ifdef	USE_LIBSCHILY
			comerr("Error opening boot image '%s' for read.\n",
							de->whole_name);
#else
			fprintf(stderr,
				"Error opening boot image '%s' for read.\n",
							de->whole_name);
			perror("");
			exit(1);
#endif
		}
		if (read(bootmbr, &disk_mbr, sizeof(disk_mbr)) !=
							sizeof(disk_mbr)) {
#ifdef	USE_LIBSCHILY
			comerr("Error reading MBR from boot image '%s'.\n",
							de->whole_name);
#else
			fprintf(stderr,
				"Error reading MBR from boot image '%s'.\n",
							de->whole_name);
			exit(1);
#endif
		}
		close(bootmbr);
		if (la_to_u_2_byte(disk_mbr.magic) != MBR_MAGIC) {
#ifdef	USE_LIBSCHILY
			errmsgno(EX_BAD,
			"Warning: boot image '%s' MBR is not a boot sector.\n",
							de->whole_name);
#else
			fprintf(stderr,
				"Warning: boot image '%s' MBR is not a boot sector.\n",
							de->whole_name);
#endif
		}
		/* find partition type */
		boot_desc_entry->sys_type[0] = PARTITION_UNUSED;
		for (i = 0; i < PARTITION_COUNT; ++i) {
			int             s_cyl_sec;
			int             e_cyl_sec;

			s_cyl_sec =
			la_to_u_2_byte(disk_mbr.partition[i].s_cyl_sec);
			e_cyl_sec =
			la_to_u_2_byte(disk_mbr.partition[i].e_cyl_sec);

			if (disk_mbr.partition[i].type != PARTITION_UNUSED) {
				if (boot_desc_entry->sys_type[0] !=
							PARTITION_UNUSED) {
#ifdef	USE_LIBSCHILY
					comerrno(EX_BAD,
					"Boot image '%s' has multiple partitions.\n",
							de->whole_name);
#else
					fprintf(stderr,
					"Boot image '%s' has multiple partitions.\n",
							de->whole_name);
					exit(1);
#endif
				}
				boot_desc_entry->sys_type[0] =
						disk_mbr.partition[i].type;

				/* a few simple sanity warnings */
				if (!boot_entry->not_bootable &&
				    disk_mbr.partition[i].status !=
							PARTITION_ACTIVE) {
					fprintf(stderr,
					"Warning: partition not marked active.\n");
				}
				if (MBR_CYLINDER(s_cyl_sec) != 0 ||
					disk_mbr.partition[i].s_head != 1 ||
					MBR_SECTOR(s_cyl_sec != 1)) {
					fprintf(stderr,
					"Warning: partition does not start at 0/1/1.\n");
				}
				geosec = (MBR_CYLINDER(e_cyl_sec) + 1) *
					(disk_mbr.partition[i].e_head + 1) *
					MBR_SECTOR(e_cyl_sec);
				if (geosec != nsectors) {
					fprintf(stderr,
					"Warning: image size does not match geometry (%d)\n",
						geosec);
				}
#ifdef DEBUG_TORITO
				fprintf(stderr, "Partition start %u/%u/%u\n",
					MBR_CYLINDER(s_cyl_sec),
					disk_mbr.partition[i].s_head,
					MBR_SECTOR(s_cyl_sec));
				fprintf(stderr, "Partition end %u/%u/%u\n",
					MBR_CYLINDER(e_cyl_sec),
					disk_mbr.partition[i].e_head,
					MBR_SECTOR(e_cyl_sec));
#endif
			}
		}
		if (boot_desc_entry->sys_type[0] == PARTITION_UNUSED) {
#ifdef	USE_LIBSCHILY
			comerrno(EX_BAD,
					"Boot image '%s' has no partitions.\n",
							de->whole_name);
#else
			fprintf(stderr,
					"Boot image '%s' has no partitions.\n",
							 de->whole_name);
			exit(1);
#endif
		}
#ifdef DEBUG_TORITO
		fprintf(stderr, "Partition type %u\n",
						boot_desc_entry->sys_type[0]);
#endif
	/* load single boot sector, in this case the MBR */
		nsectors = 1;

	} else if (boot_entry->no_emul_boot) {
		/*
		 * no emulation is a simple image boot of all the sectors
		 * in the boot image
		 */
		boot_desc_entry->boot_media[0] = EL_TORITO_MEDIA_NOEMUL;
		fprintf(stderr, "No emulation\n");

	} else {
		/* choose size of emulated floppy based on boot image size */
		if (nsectors == 2880) {
			boot_desc_entry->boot_media[0] = EL_TORITO_MEDIA_144FLOP;
			fprintf(stderr, "Emulating a 1.44 meg floppy\n");

		} else if (nsectors == 5760) {
			boot_desc_entry->boot_media[0] = EL_TORITO_MEDIA_288FLOP;
			fprintf(stderr, "Emulating a 2.88 meg floppy\n");

		} else if (nsectors == 2400) {
			boot_desc_entry->boot_media[0] = EL_TORITO_MEDIA_12FLOP;
			fprintf(stderr, "Emulating a 1.2 meg floppy\n");

		} else {
#ifdef	USE_LIBSCHILY
			comerrno(EX_BAD,
			"Error - boot image '%s' is not the an allowable size.\n",
							de->whole_name);
#else
			fprintf(stderr,
			"Error - boot image '%s' is not the an allowable size.\n",
							de->whole_name);
			exit(1);
#endif
		}

		/* load single boot sector for floppies */
		nsectors = 1;
	}

	/* fill in boot image details */
#ifdef DEBUG_TORITO
	fprintf(stderr, "Boot %u sectors\n", nsectors);
	fprintf(stderr, "Extent of boot images is %d\n",
				get_733(de->isorec.extent));
#endif
	set_721(boot_desc_entry->nsect, (unsigned int) nsectors);
	set_731(boot_desc_entry->bootoff,
		(unsigned int) get_733(de->isorec.extent));


	/* If the user has asked for it, patch the boot image */
	if (boot_entry->boot_info_table) {
		int             bootimage;
		unsigned int    bi_checksum,
		                total_len;
		static char     csum_buffer[SECTOR_SIZE];
		int             len;
		struct mkisofs_boot_info bi_table;

		bootimage = open(de->whole_name, O_RDWR | O_BINARY);
		if (bootimage == -1) {
#ifdef	USE_LIBSCHILY
			comerr(
			"Error opening boot image file '%s' for update.\n",
							de->whole_name);
#else
			fprintf(stderr,
			"Error opening boot image file '%s' for update.\n",
							de->whole_name);
			perror("");
			exit(1);
#endif
		}
	/* Compute checksum of boot image, sans 64 bytes */
		total_len = 0;
		bi_checksum = 0;
		while ((len = read(bootimage, csum_buffer, SECTOR_SIZE)) > 0) {
			if (total_len & 3) {
#ifdef	USE_LIBSCHILY
				comerrno(EX_BAD,
				"Odd alignment at non-end-of-file in boot image '%s'.\n",
							de->whole_name);
#else
				fprintf(stderr,
				"Odd alignment at non-end-of-file in boot image '%s'.\n",
							de->whole_name);
				exit(1);
#endif
			}
			if (total_len < 64)
				memset(csum_buffer, 0, 64 - total_len);
			if (len < SECTOR_SIZE)
				memset(csum_buffer + len, 0, SECTOR_SIZE-len);
			for (i = 0; i < SECTOR_SIZE; i += 4)
				bi_checksum += get_731(&csum_buffer[i]);
			total_len += len;
		}

		if (total_len != de->size) {
#ifdef	USE_LIBSCHILY
			comerrno(EX_BAD,
			"Boot image file '%s' changed underneath us!\n",
						de->whole_name);
#else
			fprintf(stderr,
			"Boot image file '%s' changed underneath us!\n",
						de->whole_name);
			exit(1);
#endif
		}
		/* End of file, set position to byte 8 */
		lseek(bootimage, 8, SEEK_SET);
		memset(&bi_table, 0, sizeof(bi_table));
		/* Is it always safe to assume PVD is at session_start+16? */
		set_731(bi_table.bi_pvd, session_start + 16);
		set_731(bi_table.bi_file, de->starting_block);
		set_731(bi_table.bi_length, de->size);
		set_731(bi_table.bi_csum, bi_checksum);

		write(bootimage, &bi_table, sizeof(bi_table));
		close(bootimage);
	}
}/* fill_boot_desc(... */

void
get_boot_entry()
{
	if (current_boot_entry)
		return;

	current_boot_entry = (struct eltorito_boot_entry_info*)
			e_malloc(sizeof(struct eltorito_boot_entry_info));
	memset(current_boot_entry, 0, sizeof(*current_boot_entry));

	if (!first_boot_entry) {
		first_boot_entry = current_boot_entry;
		last_boot_entry = current_boot_entry;
	} else {
		last_boot_entry->next = current_boot_entry;
		last_boot_entry = current_boot_entry;
	}
}

void
new_boot_entry()
{
	current_boot_entry = NULL;
}

/*
 * Function to write the EVD for the disc.
 */
static int
tvd_write(outfile)
	FILE	*outfile;
{
	/* check the boot image is not NULL */
	if (!boot_image) {
#ifdef	USE_LIBSCHILY
		comerrno(EX_BAD, "No boot image specified.\n");
#else
		fprintf(stderr, "No boot image specified.\n");
		exit(1);
#endif
	}
	/* Next we write out the boot volume descriptor for the disc */
	get_torito_desc(&gboot_desc);
	xfwrite(&gboot_desc, 1, SECTOR_SIZE, outfile);
	last_extent_written++;
	return 0;
}

struct output_fragment torito_desc = {NULL, oneblock_size, NULL, tvd_write};