ldm.c

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/*
 * ldm - Part of the Linux-NTFS project.
 *
 * Copyright (C) 2001 Richard Russon <[e-mail]>
 * Copyright (C) 2001 Anton Altaparmakov <[e-mail]> (AIA)
 *
 * Documentation is available at http://linux-ntfs.sf.net/ldm
 *
 * 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; either version 2 of the License, or (at your option)
 * any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program (in the main directory of the Linux-NTFS source
 * in the file COPYING); if not, write to the Free Software Foundation,
 * Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 * 28/10/2001 - Added sorting of ldm partitions. (AIA)
 */
#include <linux/types.h>
#include <asm/unaligned.h>
#include <asm/byteorder.h>
#include <linux/genhd.h>
#include <linux/blkdev.h>
#include <linux/slab.h>
#include "check.h"
#include "ldm.h"
#include "msdos.h"

#if 0 /* Fool kernel-doc since it doesn't do macros yet. */
/**
 * ldm_debug - output an error message if debugging was enabled at compile time
 * @f:		a printf format string containing the message
 * @...:	the variables to substitute into @f
 *
 * ldm_debug() writes a DEBUG level message to the syslog but only if the
 * driver was compiled with debug enabled. Otherwise, the call turns into a NOP.
 */
static void ldm_debug(const char *f, ...);
#endif
#ifdef CONFIG_LDM_DEBUG
#define ldm_debug(f, a...)						\
	{								\
		printk(LDM_DEBUG " DEBUG (%s, %d): %s: ",		\
				__FILE__, __LINE__, __FUNCTION__);	\
		printk(f, ##a);						\
	}
#else	/* !CONFIG_LDM_DEBUG */
#define ldm_debug(f, a...)	do {} while (0)
#endif	/* !CONFIG_LDM_DEBUG */

/* Necessary forward declarations. */
static int create_partition(struct gendisk *, int, int, int);
static int parse_privhead(const u8 *, struct privhead *);
static u64 get_vnum(const u8 *, int *);
static int get_vstr(const u8 *, u8 *, const int);

/**
 * parse_vblk_part - parse a LDM database vblk partition record
 * @buffer:	vblk partition record loaded from the LDM database
 * @buf_size:	size of @buffer in bytes
 * @vb:		in memory vblk structure to return parsed information in
 *
 * This parses the LDM database vblk record of type VBLK_PART, i.e. a partition
 * record, supplied in @buffer and sets up the in memory vblk structure @vb
 * with the obtained information.
 *
 * Return 1 on success and -1 on error, in which case @vb is undefined.
 */
static int parse_vblk_part(const u8 *buffer, const int buf_size,
		struct vblk *vb)
{
	int err, rel_objid, rel_name, rel_size, rel_parent;

	if (0x34 >= buf_size)
		return -1;
	/* Calculate relative offsets. */
	rel_objid  = 1 + buffer[0x18];
	if (0x18 + rel_objid >= buf_size)
		return -1;
	rel_name   = 1 + buffer[0x18 + rel_objid] + rel_objid;
	if (0x34 + rel_name >= buf_size)
		return -1;
	rel_size   = 1 + buffer[0x34 + rel_name] + rel_name;
	if (0x34 + rel_size >= buf_size)
		return -1;
	rel_parent = 1 + buffer[0x34 + rel_size] + rel_size;
	if (0x34 + rel_parent >= buf_size)
		return -1;
	/* Setup @vb. */
	vb->vblk_type    = VBLK_PART;
	vb->obj_id       = get_vnum(buffer + 0x18, &err);
	if (err || 0x34 + rel_parent + buffer[0x34 + rel_parent] >= buf_size)
		return -1;
	vb->disk_id      = get_vnum(buffer + 0x34 + rel_parent, &err);
	if (err || 0x24 + rel_name + 8 > buf_size)
		return -1;
	vb->start_sector = BE64(buffer + 0x24 + rel_name);
	if (0x34 + rel_name + buffer[0x34 + rel_name] >= buf_size)
		return -1;
	vb->num_sectors  = get_vnum(buffer + 0x34 + rel_name, &err);
	if (err || 0x18 + rel_objid + buffer[0x18 + rel_objid] >= buf_size)
		return -1;
	err = get_vstr(buffer + 0x18 + rel_objid, vb->name, sizeof(vb->name));
	if (err == -1)
		return err;
	ldm_debug("Parsed Partition VBLK successfully.\n");
	return 1;
}

/**
 * parse_vblk - parse a LDM database vblk record
 * @buffer:	vblk record loaded from the LDM database
 * @buf_size:	size of @buffer in bytes
 * @vb:		in memory vblk structure to return parsed information in
 *
 * This parses the LDM database vblk record supplied in @buffer and sets up
 * the in memory vblk structure @vb with the obtained information.
 *
 * Return 1 on success, 0 if successful but record not in use, and -1 on error.
 * If the return value is 0 or -1, @vb is undefined.
 *
 * NOTE: Currently the only record type we handle is VBLK_PART, i.e. records
 * describing a partition. For all others, we just set @vb->vblk_type to 0 and
 * return success. This of course means that if @vb->vblk_type is zero, all
 * other fields in @vb are undefined.
 */
static int parse_vblk(const u8 *buffer, const int buf_size, struct vblk *vb)
{
	int err = 1;

	if (buf_size < 0x14)
		return -1;
	if (MAGIC_VBLK != BE32(buffer)) {
		printk(LDM_CRIT "Cannot find VBLK, database may be corrupt.\n");
		return -1;
	}
	if ((BE16(buffer + 0x0E) == 0) ||       /* Record is not in use. */
	    (BE16(buffer + 0x0C) != 0))         /* Part 2 of an ext. record */
		return 0;
	/* FIXME: What about extended VBLKs? */
	switch (buffer[0x13]) {
	case VBLK_PART:
		err = parse_vblk_part(buffer, buf_size, vb);
		break;
	default:
		vb->vblk_type = 0;
	}
	if (err != -1)
		ldm_debug("Parsed VBLK successfully.\n");
	return err;
}

/**
 * add_partition_to_list - insert partition into a partition list
 * @pl:		sorted list of partitions
 * @hd:		gendisk structure to which the data partition belongs
 * @disk_minor:	minor number of the disk device
 * @start:	first sector within the disk device
 * @size:	number of sectors on the partition device
 *
 * This sanity checks the partition specified by @start and @size against the
 * device specified by @hd and inserts the partition into the sorted partition
 * list @pl if the checks pass.
 *
 * On success return 1, otherwise return -1.
 *
 * TODO: Add sanity check for overlapping partitions. (AIA)
 */ 
static int add_partition_to_list(struct list_head *pl, const struct gendisk *hd,
		const int disk_minor, const unsigned long start,
		const unsigned long size)
{
	struct ldm_part *lp, *lptmp;
	struct list_head *tmp;

	if (!hd->part)
		return -1;
	if ((start < 1) || ((start + size) > hd->part[disk_minor].nr_sects)) {
		printk(LDM_CRIT "LDM partition exceeds physical disk. "
				"Skipping.\n");
		return -1;
	}
	lp = (struct ldm_part*)kmalloc(sizeof(struct ldm_part), GFP_KERNEL);
	if (!lp) {
		printk(LDM_CRIT "Not enough memory! Aborting LDM partition "
				"parsing.\n");
		return -2;
	}
	INIT_LIST_HEAD(&lp->part_list);
	lp->start = start;
	lp->size = size;
	list_for_each(tmp, pl) {
		lptmp = list_entry(tmp, struct ldm_part, part_list);
		if (start > lptmp->start)
			continue;
		if (start < lptmp->start)
			break;
		printk(LDM_CRIT "Duplicate LDM partition entry! Skipping.\n");
		kfree(lp);
		return -1;
	}
	list_add_tail(&lp->part_list, tmp);
	ldm_debug("Added LDM partition successfully.\n");
	return 1;
}

/**
 * create_data_partitions - create the data partition devices
 * @hd:			gendisk structure in which to create the data partitions
 * @first_sector:	first sector within the disk device
 * @first_part_minor:	first minor number of data partition devices
 * @dev:		partition device holding the LDM database
 * @vm:			in memory vmdb structure of @dev
 * @ph:			in memory privhead structure of the disk device
 * @dk:			in memory ldmdisk structure of the disk device
 *
 * The database contains ALL the partitions for ALL the disks, so we need to
 * filter out this specific disk. Using the disk's object id, we can find all
 * the partitions in the database that belong to this disk.
 *
 * For each found partition, we create a corresponding partition device starting
 * with minor number @first_part_minor. But we do this in such a way that we
 * actually sort the partitions in order of on-disk position. Any invalid
 * partitions are completely ignored/skipped (an error is output but that's
 * all).
 *
 * Return 1 on success and -1 on error.
 */
static int create_data_partitions(struct gendisk *hd,
		const unsigned long first_sector, int first_part_minor,
		struct block_device *bdev, const struct vmdb *vm,
		const struct privhead *ph, const struct ldmdisk *dk,
		unsigned long base)
{
	Sector sect;
	unsigned char *data;
	struct vblk *vb;
	LIST_HEAD(pl);		/* Sorted list of partitions. */
	struct ldm_part *lp;
	struct list_head *tmp;
	int vblk;
	int vsize;		/* VBLK size. */
	int perbuf;		/* VBLKs per buffer. */
	int buffer, lastbuf, lastofs, err, disk_minor;

	vb = (struct vblk*)kmalloc(sizeof(struct vblk), GFP_KERNEL);
	if (!vb)
		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;
	/*
	 * Get the minor number of the parent device so we can check we don't
	 * go beyond the end of the device.
	 */
	disk_minor = (first_part_minor >> hd->minor_shift) << hd->minor_shift;
	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++) {
			u8 *block;
			
			if (lastofs && buffer == lastbuf - 1 && vblk >= lastofs)
				break;
			block = data + vsize * vblk;
			if (block + vsize > data + 512)
				goto brelse_out;
			if (parse_vblk(block, vsize, vb) != 1)
				continue;
			if (vb->vblk_type != VBLK_PART)
				continue;
			if (dk->obj_id != vb->disk_id)
				continue;
			/* Ignore invalid partition errors. */
			if (add_partition_to_list(&pl, hd, disk_minor,
					first_sector + vb->start_sector +
					ph->logical_disk_start,
					vb->num_sectors) < -1)
				goto brelse_out;
		}
		put_dev_sector(sect);
	}
	err = 1;
out:
	/* Finally create the nicely sorted data partitions. */
	printk(" <");
	list_for_each(tmp, &pl) {
		lp = list_entry(tmp, struct ldm_part, part_list);
		add_gd_partition(hd, first_part_minor++, lp->start, lp->size);
	}
	printk(" >\n");
	if (!list_empty(&pl)) {
		struct list_head *tmp2;

		/* Cleanup the partition list which is now superfluous. */
		list_for_each_safe(tmp, tmp2, &pl) {
			lp = list_entry(tmp, struct ldm_part, part_list);
			list_del(tmp);
			kfree(lp);
		}
	}
	kfree(vb);
	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 create_partitions.\n");
err_out:
	err = -1;
	goto out;
}

/**
 * get_vnum - convert a variable-width, big endian number, to cpu u64 one
 * @block:	pointer to the variable-width number to convert
 * @err:	address of an integer into which to return the error code.
 *
 * This converts a variable-width, big endian number into a 64-bit, CPU format
 * number and returns the result with err set to 0. If an error occurs return 0
 * with err set to -1.
 *
 * The first byte of a variable-width number is the size of the number in bytes.
 */
static u64 get_vnum(const u8 *block, int *err)
{
	u64 tmp = 0ULL;
	u8 length = *block++;

	if (length && length <= 8) {
		while (length--)
			tmp = (tmp << 8) | *block++;
		*err = 0;
	} else {
		printk(LDM_ERR "Illegal length in get_vnum(): %d.\n", length);
		*err = 1;