ldm.c

ARM 嵌入式 系统 设计与实例开发 实验教材 二源码

	}
	return tmp;
}

/**
 * get_vstr - convert a counted, non-null-terminated ASCII string to C-style one
 * @block:	string to convert
 * @buffer:	output buffer
 * @buflen:	size of output buffer
 *
 * This converts @block, a counted, non-null-terminated ASCII string, into a
 * C-style, null-terminated, ASCII string and returns this in @buffer. The
 * maximum number of characters converted is given by @buflen.
 *
 * The first bytes of a counted string stores the length of the string in bytes.
 *
 * Return the number of characters written to @buffer, not including the
 * terminating null character, on success, and -1 on error, in which case
 * @buffer is not defined.
 */
static int get_vstr(const u8 *block, u8 *buffer, const int buflen)
{
	int length = block[0];

	if (length < 1)
		return -1;
	if (length >= buflen) {
		printk(LDM_ERR "String too long for buffer in get_vstr(): "
				"(%d/%d). Truncating.\n", length, buflen);
		length = buflen - 1;
	}
	memcpy(buffer, block + 1, length);
	buffer[length] = (u8)'\0';
	return length;
}

/**
 * get_disk_objid - obtain the object id for the device we are working on
 * @dev:	partition device holding the LDM database
 * @vm:		in memory vmdb structure of the LDM database
 * @ph:		in memory privhead structure of the device we are working on
 * @dk:		in memory ldmdisk structure to return information into
 *
 * This obtains the object id for the device we are working on as defined by
 * the private header @ph. The obtained object id, together with the disk's
 * GUID from @ph are returned in the ldmdisk structure pointed to by @dk.
 *
 * A Disk has two Ids. The main one is a GUID in string format. The second,
 * used internally for cross-referencing, is a small, sequentially allocated,
 * number. The PRIVHEAD, just after the partition table, tells us the disk's
 * GUID. To find the disk's object id, we have to look through the database.
 *
 * Return 1 on success and -1 on error, in which case @dk is undefined.
 */
static int get_disk_objid(struct block_device *bdev, const struct vmdb *vm,
		const struct privhead *ph, struct ldmdisk *dk,
		unsigned long base)
{
	Sector sect;
	unsigned char *data;
	u8 *disk_id;
	int vblk;
	int vsize;		/* VBLK size. */
	int perbuf;		/* VBLKs per buffer. */
	int buffer, lastbuf, lastofs, err;

	disk_id = (u8*)kmalloc(DISK_ID_SIZE, GFP_KERNEL);
	if (!disk_id)
		goto no_mem;
	vsize   = vm->vblk_size;
	if (vsize < 1 || vsize > 512)
		goto err_out;
	perbuf  = 512 / vsize;
	if (perbuf < 1 || 512 % vsize)
		goto err_out;
					/* 512 == VMDB size */
	lastbuf = vm->last_vblk_seq / perbuf - 1;
	lastofs = vm->last_vblk_seq % perbuf;
	if (lastofs)
		lastbuf++;
	if (OFF_VBLK * LDM_BLOCKSIZE + vm->last_vblk_seq * vsize >
			ph->config_size * 512)
		goto err_out;
	for (buffer = 0; buffer < lastbuf; buffer++) {
		data = read_dev_sector(bdev, base + 2*OFF_VBLK + buffer, &sect);
		if (!data)
			goto read_err;
		for (vblk = 0; vblk < perbuf; vblk++) {
			int rel_objid, rel_name, delta;
			u8 *block;

			if (lastofs && buffer == lastbuf - 1 && vblk >= lastofs)
				break;
			block = data + vblk * vsize;
			delta = vblk * vsize + 0x18;
			if (delta >= 512)
				goto brelse_out;
			if (block[0x0D] != 0)	/* Extended VBLK, ignore */
				continue;
			if ((block[0x13] != VBLK_DSK1) &&
			    (block[0x13] != VBLK_DSK2))
				continue;
			/* Calculate relative offsets. */
			rel_objid = 1 + block[0x18];
			if (delta + rel_objid >= 512)
				goto brelse_out;
			rel_name  = 1 + block[0x18 + rel_objid] + rel_objid;
			if (delta + rel_name >= 512 ||
			    delta + rel_name + block[0x18 + rel_name] >= 512)
				goto brelse_out;
			err = get_vstr(block + 0x18 + rel_name, disk_id,
					DISK_ID_SIZE);
			if (err == -1)
				goto brelse_out;
			if (!strncmp(disk_id, ph->disk_id, DISK_ID_SIZE)) {
				dk->obj_id = get_vnum(block + 0x18, &err);
				put_dev_sector(sect);
				if (err)
					goto out;
				strncpy(dk->disk_id, ph->disk_id,
						sizeof(dk->disk_id));
				dk->disk_id[sizeof(dk->disk_id) - 1] = (u8)'\0';
				err = 1;
				goto out;
			}
		}
		put_dev_sector(sect);
	}
	err = -1;
out:
	kfree(disk_id);
	return err;
brelse_out:
	put_dev_sector(sect);
	goto err_out;
no_mem:
	printk(LDM_CRIT "Not enough memory to allocate required buffers.\n");
	goto err_out;
read_err:
	printk(LDM_CRIT "Disk read failed in get_disk_objid.\n");
err_out:
	err = -1;
	goto out;
}

/**
 * parse_vmdb - parse the LDM database vmdb structure
 * @buffer:	LDM database vmdb structure loaded from the device
 * @vm:		in memory vmdb structure to return parsed information in
 *
 * This parses the LDM database vmdb structure supplied in @buffer and sets up
 * the in memory vmdb structure @vm with the obtained information.
 *
 * Return 1 on success and -1 on error, in which case @vm is undefined.
 *
 * NOTE: The *_start, *_size and *_seq values returned in @vm have not been
 * checked for validity, so make sure to check them when using them.
 */
static int parse_vmdb(const u8 *buffer, struct vmdb *vm)
{
	if (MAGIC_VMDB != BE32(buffer)) {
		printk(LDM_CRIT "Cannot find VMDB, database may be corrupt.\n");
		return -1;
	}
	vm->ver_major = BE16(buffer + 0x12);
	vm->ver_minor = BE16(buffer + 0x14);
	if ((vm->ver_major != 4) || (vm->ver_minor != 10)) {
		printk(LDM_ERR "Expected VMDB version %d.%d, got %d.%d. "
				"Aborting.\n", 4, 10, vm->ver_major,
				vm->ver_minor);
		return -1;
	}
	vm->vblk_size	  = BE32(buffer + 0x08);
	vm->vblk_offset   = BE32(buffer + 0x0C);
	vm->last_vblk_seq = BE32(buffer + 0x04);

	ldm_debug("Parsed VMDB successfully.\n");
	return 1;
}

/**
 * validate_vmdb - validate the vmdb
 * @dev:	partition device holding the LDM database
 * @vm:		in memory vmdb in which to return information
 *
 * Find the vmdb of the LDM database stored on @dev and return the parsed
 * information into @vm.
 *
 * Return 1 on success and -1 on error, in which case @vm is undefined.
 */
static int validate_vmdb(struct block_device *bdev, struct vmdb *vm, unsigned long base)
{
	Sector sect;
	unsigned char *data;
	int ret;

	data = read_dev_sector(bdev, base + OFF_VMDB * 2 + 1, &sect);
	if (!data) {
		printk(LDM_CRIT "Disk read failed in validate_vmdb.\n");
		return -1;
	}
	ret = parse_vmdb(data, vm);
	put_dev_sector(sect);
	return ret;
}

/**
 * compare_tocblocks - compare two tables of contents
 * @toc1:	first toc
 * @toc2:	second toc
 *
 * This compares the two tables of contents @toc1 and @toc2.
 *
 * Return 1 if @toc1 and @toc2 are equal and -1 otherwise.
 */
static int compare_tocblocks(const struct tocblock *toc1,
		const struct tocblock *toc2)
{
	if ((toc1->bitmap1_start == toc2->bitmap1_start)	&&
	    (toc1->bitmap1_size  == toc2->bitmap1_size)		&&
	    (toc1->bitmap2_start == toc2->bitmap2_start)	&&
	    (toc1->bitmap2_size  == toc2->bitmap2_size)		&&
	    !strncmp(toc1->bitmap1_name, toc2->bitmap1_name,
			sizeof(toc1->bitmap1_name))		&&
	    !strncmp(toc1->bitmap2_name, toc2->bitmap2_name,
			sizeof(toc1->bitmap2_name)))
		return 1;
	return -1;
}

/**
 * parse_tocblock - parse the LDM database table of contents structure
 * @buffer:	LDM database toc structure loaded from the device
 * @toc:	in memory toc structure to return parsed information in
 *
 * This parses the LDM database table of contents structure supplied in @buffer
 * and sets up the in memory table of contents structure @toc with the obtained
 * information.
 *
 * Return 1 on success and -1 on error, in which case @toc is undefined.
 *
 * FIXME: The *_start and *_size values returned in @toc are not been checked
 * for validity but as we don't use the actual values for anything other than
 * comparing between the toc and its backups, the values are not important.
 */
static int parse_tocblock(const u8 *buffer, struct tocblock *toc)
{
	if (MAGIC_TOCBLOCK != BE64(buffer)) {
		printk(LDM_CRIT "Cannot find TOCBLOCK, database may be "
				"corrupt.\n");
		return -1;
	}
	strncpy(toc->bitmap1_name, buffer + 0x24, sizeof(toc->bitmap1_name));
	toc->bitmap1_name[sizeof(toc->bitmap1_name) - 1] = (u8)'\0';
	toc->bitmap1_start = BE64(buffer + 0x2E);
	toc->bitmap1_size  = BE64(buffer + 0x36);
	/*toc->bitmap1_flags = BE64(buffer + 0x3E);*/
	if (strncmp(toc->bitmap1_name, TOC_BITMAP1,
			sizeof(toc->bitmap1_name)) != 0) {
		printk(LDM_CRIT "TOCBLOCK's first bitmap should be %s, but is "
				"%s.\n", TOC_BITMAP1, toc->bitmap1_name);
		return -1;
	}
	strncpy(toc->bitmap2_name, buffer + 0x46, sizeof(toc->bitmap2_name));
	toc->bitmap2_name[sizeof(toc->bitmap2_name) - 1] = (u8)'\0';
	toc->bitmap2_start = BE64(buffer + 0x50);
	toc->bitmap2_size  = BE64(buffer + 0x58);
	/*toc->bitmap2_flags = BE64(buffer + 0x60);*/
	if (strncmp(toc->bitmap2_name, TOC_BITMAP2,
			sizeof(toc->bitmap2_name)) != 0) {
		printk(LDM_CRIT "TOCBLOCK's second bitmap should be %s, but is "
				"%s.\n", TOC_BITMAP2, toc->bitmap2_name);
		return -1;
	}
	ldm_debug("Parsed TOCBLOCK successfully.\n");
	return 1;
}

/**
 * validate_tocblocks - validate the table of contents and its backups
 * @dev:	partition device holding the LDM database
 * @toc1:	in memory table of contents in which to return information
 *
 * Find and compare the four tables of contents of the LDM database stored on
 * @dev and return the parsed information into @toc1.
 *
 * Return 1 on success and -1 on error, in which case @toc1 is undefined.
 */
static int validate_tocblocks(struct block_device *bdev,
			struct tocblock *toc1,
			unsigned long base)
{
	Sector sect;
	unsigned char *data;
	struct tocblock *toc2 = NULL, *toc3 = NULL, *toc4 = NULL;
	int err;

	toc2 = (struct tocblock*)kmalloc(sizeof(*toc2), GFP_KERNEL);
	if (!toc2)
		goto no_mem;
	toc3 = (struct tocblock*)kmalloc(sizeof(*toc3), GFP_KERNEL);
	if (!toc3)
		goto no_mem;
	toc4 = (struct tocblock*)kmalloc(sizeof(*toc4), GFP_KERNEL);
	if (!toc4)
		goto no_mem;
	/* Read and parse first toc. */
	data = read_dev_sector(bdev, base + OFF_TOCBLOCK1 * 2 + 1, &sect);
	if (!data) {
		printk(LDM_CRIT "Disk read 1 failed in validate_tocblocks.\n");
		goto err_out;
	}
	err = parse_tocblock(data, toc1);
	put_dev_sector(sect);
	if (err != 1)
		goto out;
	/* Read and parse second toc. */
	data = read_dev_sector(bdev, base + OFF_TOCBLOCK2 * 2, &sect);
	if (!data) {
		printk(LDM_CRIT "Disk read 2 failed in validate_tocblocks.\n");
		goto err_out;
	}
	err = parse_tocblock(data, toc2);
	put_dev_sector(sect);
	if (err != 1)
		goto out;
	/* Read and parse third toc. */
	data = read_dev_sector(bdev, base + OFF_TOCBLOCK3 * 2 + 1, &sect);
	if (!data) {
		printk(LDM_CRIT "Disk read 3 failed in validate_tocblocks.\n");
		goto err_out;
	}
	err = parse_tocblock(data, toc3);
	put_dev_sector(sect);
	if (err != 1)
		goto out;
	/* Read and parse fourth toc. */
	data = read_dev_sector(bdev, base + OFF_TOCBLOCK4 * 2, &sect);
	if (!data) {
		printk(LDM_CRIT "Disk read 4 failed in validate_tocblocks.\n");
		goto err_out;
	}
	err = parse_tocblock(data, toc4);
	put_dev_sector(sect);
	if (err != 1)
		goto out;
	/* Compare all tocs. */
	err = compare_tocblocks(toc1, toc2);
	if (err != 1) {
		printk(LDM_CRIT "First and second TOCBLOCKs don't match.\n");
		goto out;
	}
	err = compare_tocblocks(toc3, toc4);
	if (err != 1) {
		printk(LDM_CRIT "Third and fourth TOCBLOCKs don't match.\n");
		goto out;
	}
	err = compare_tocblocks(toc1, toc3);