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ldm.c

/**
 * ldm - Support for Windows Logical Disk Manager (Dynamic Disks)
 *
 * Copyright (C) 2001,2002 Richard Russon <ldm@flatcap.org>
 * Copyright (c) 2001-2007 Anton Altaparmakov
 * Copyright (C) 2001,2002 Jakob Kemi <jakob.kemi@telia.com>
 *
 * Documentation is available at http://www.linux-ntfs.org/content/view/19/37/
 *
 * 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 source in the file COPYING); if
 * not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
 * Boston, MA  02111-1307  USA
 */

#include <linux/slab.h>
#include <linux/pagemap.h>
#include <linux/stringify.h>
#include "ldm.h"
#include "check.h"
#include "msdos.h"

/**
 * ldm_debug/info/error/crit - Output an error message
 * @f:    A printf format string containing the message
 * @...:  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.
 */
#ifndef CONFIG_LDM_DEBUG
#define ldm_debug(...)  do {} while (0)
#else
#define ldm_debug(f, a...) _ldm_printk (KERN_DEBUG, __FUNCTION__, f, ##a)
#endif

#define ldm_crit(f, a...)  _ldm_printk (KERN_CRIT,  __FUNCTION__, f, ##a)
#define ldm_error(f, a...) _ldm_printk (KERN_ERR,   __FUNCTION__, f, ##a)
#define ldm_info(f, a...)  _ldm_printk (KERN_INFO,  __FUNCTION__, f, ##a)

__attribute__ ((format (printf, 3, 4)))
static void _ldm_printk (const char *level, const char *function,
                   const char *fmt, ...)
{
      static char buf[128];
      va_list args;

      va_start (args, fmt);
      vsnprintf (buf, sizeof (buf), fmt, args);
      va_end (args);

      printk ("%s%s(): %s\n", level, function, buf);
}

/**
 * ldm_parse_hexbyte - Convert a ASCII hex number to a byte
 * @src:  Pointer to at least 2 characters to convert.
 *
 * Convert a two character ASCII hex string to a number.
 *
 * Return:  0-255  Success, the byte was parsed correctly
 *          -1     Error, an invalid character was supplied
 */
static int ldm_parse_hexbyte (const u8 *src)
{
      unsigned int x;         /* For correct wrapping */
      int h;

      /* high part */
      if      ((x = src[0] - '0') <= '9'-'0') h = x;
      else if ((x = src[0] - 'a') <= 'f'-'a') h = x+10;
      else if ((x = src[0] - 'A') <= 'F'-'A') h = x+10;
      else return -1;
      h <<= 4;

      /* low part */
      if ((x = src[1] - '0') <= '9'-'0') return h | x;
      if ((x = src[1] - 'a') <= 'f'-'a') return h | (x+10);
      if ((x = src[1] - 'A') <= 'F'-'A') return h | (x+10);
      return -1;
}

/**
 * ldm_parse_guid - Convert GUID from ASCII to binary
 * @src:   36 char string of the form fa50ff2b-f2e8-45de-83fa-65417f2f49ba
 * @dest:  Memory block to hold binary GUID (16 bytes)
 *
 * N.B. The GUID need not be NULL terminated.
 *
 * Return:  'true'   @dest contains binary GUID
 *          'false'  @dest contents are undefined
 */
static bool ldm_parse_guid (const u8 *src, u8 *dest)
{
      static const int size[] = { 4, 2, 2, 2, 6 };
      int i, j, v;

      if (src[8]  != '-' || src[13] != '-' ||
          src[18] != '-' || src[23] != '-')
            return false;

      for (j = 0; j < 5; j++, src++)
            for (i = 0; i < size[j]; i++, src+=2, *dest++ = v)
                  if ((v = ldm_parse_hexbyte (src)) < 0)
                        return false;

      return true;
}

/**
 * ldm_parse_privhead - Read the LDM Database PRIVHEAD structure
 * @data:  Raw database PRIVHEAD structure loaded from the device
 * @ph:    In-memory privhead structure in which to return parsed information
 *
 * This parses the LDM database PRIVHEAD structure supplied in @data and
 * sets up the in-memory privhead structure @ph with the obtained information.
 *
 * Return:  'true'   @ph contains the PRIVHEAD data
 *          'false'  @ph contents are undefined
 */
static bool ldm_parse_privhead(const u8 *data, struct privhead *ph)
{
      bool is_vista = false;

      BUG_ON(!data || !ph);
      if (MAGIC_PRIVHEAD != BE64(data)) {
            ldm_error("Cannot find PRIVHEAD structure. LDM database is"
                  " corrupt. Aborting.");
            return false;
      }
      ph->ver_major = BE16(data + 0x000C);
      ph->ver_minor = BE16(data + 0x000E);
      ph->logical_disk_start = BE64(data + 0x011B);
      ph->logical_disk_size = BE64(data + 0x0123);
      ph->config_start = BE64(data + 0x012B);
      ph->config_size = BE64(data + 0x0133);
      /* Version 2.11 is Win2k/XP and version 2.12 is Vista. */
      if (ph->ver_major == 2 && ph->ver_minor == 12)
            is_vista = true;
      if (!is_vista && (ph->ver_major != 2 || ph->ver_minor != 11)) {
            ldm_error("Expected PRIVHEAD version 2.11 or 2.12, got %d.%d."
                  " Aborting.", ph->ver_major, ph->ver_minor);
            return false;
      }
      ldm_debug("PRIVHEAD version %d.%d (Windows %s).", ph->ver_major,
                  ph->ver_minor, is_vista ? "Vista" : "2000/XP");
      if (ph->config_size != LDM_DB_SIZE) {     /* 1 MiB in sectors. */
            /* Warn the user and continue, carefully. */
            ldm_info("Database is normally %u bytes, it claims to "
                  "be %llu bytes.", LDM_DB_SIZE,
                  (unsigned long long)ph->config_size);
      }
      if ((ph->logical_disk_size == 0) || (ph->logical_disk_start +
                  ph->logical_disk_size > ph->config_start)) {
            ldm_error("PRIVHEAD disk size doesn't match real disk size");
            return false;
      }
      if (!ldm_parse_guid(data + 0x0030, ph->disk_id)) {
            ldm_error("PRIVHEAD contains an invalid GUID.");
            return false;
      }
      ldm_debug("Parsed PRIVHEAD successfully.");
      return true;
}

/**
 * ldm_parse_tocblock - Read the LDM Database TOCBLOCK structure
 * @data:  Raw database TOCBLOCK structure loaded from the device
 * @toc:   In-memory toc structure in which to return parsed information
 *
 * This parses the LDM Database TOCBLOCK (table of contents) structure supplied
 * in @data and sets up the in-memory tocblock structure @toc with the obtained
 * information.
 *
 * N.B.  The *_start and *_size values returned in @toc are not range-checked.
 *
 * Return:  'true'   @toc contains the TOCBLOCK data
 *          'false'  @toc contents are undefined
 */
static bool ldm_parse_tocblock (const u8 *data, struct tocblock *toc)
{
      BUG_ON (!data || !toc);

      if (MAGIC_TOCBLOCK != BE64 (data)) {
            ldm_crit ("Cannot find TOCBLOCK, database may be corrupt.");
            return false;
      }
      strncpy (toc->bitmap1_name, data + 0x24, sizeof (toc->bitmap1_name));
      toc->bitmap1_name[sizeof (toc->bitmap1_name) - 1] = 0;
      toc->bitmap1_start = BE64 (data + 0x2E);
      toc->bitmap1_size  = BE64 (data + 0x36);

      if (strncmp (toc->bitmap1_name, TOC_BITMAP1,
                  sizeof (toc->bitmap1_name)) != 0) {
            ldm_crit ("TOCBLOCK's first bitmap is '%s', should be '%s'.",
                        TOC_BITMAP1, toc->bitmap1_name);
            return false;
      }
      strncpy (toc->bitmap2_name, data + 0x46, sizeof (toc->bitmap2_name));
      toc->bitmap2_name[sizeof (toc->bitmap2_name) - 1] = 0;
      toc->bitmap2_start = BE64 (data + 0x50);
      toc->bitmap2_size  = BE64 (data + 0x58);
      if (strncmp (toc->bitmap2_name, TOC_BITMAP2,
                  sizeof (toc->bitmap2_name)) != 0) {
            ldm_crit ("TOCBLOCK's second bitmap is '%s', should be '%s'.",
                        TOC_BITMAP2, toc->bitmap2_name);
            return false;
      }
      ldm_debug ("Parsed TOCBLOCK successfully.");
      return true;
}

/**
 * ldm_parse_vmdb - Read the LDM Database VMDB structure
 * @data:  Raw database VMDB structure loaded from the device
 * @vm:    In-memory vmdb structure in which to return parsed information
 *
 * This parses the LDM Database VMDB structure supplied in @data and sets up
 * the in-memory vmdb structure @vm with the obtained information.
 *
 * N.B.  The *_start, *_size and *_seq values will be range-checked later.
 *
 * Return:  'true'   @vm contains VMDB info
 *          'false'  @vm contents are undefined
 */
static bool ldm_parse_vmdb (const u8 *data, struct vmdb *vm)
{
      BUG_ON (!data || !vm);

      if (MAGIC_VMDB != BE32 (data)) {
            ldm_crit ("Cannot find the VMDB, database may be corrupt.");
            return false;
      }

      vm->ver_major = BE16 (data + 0x12);
      vm->ver_minor = BE16 (data + 0x14);
      if ((vm->ver_major != 4) || (vm->ver_minor != 10)) {
            ldm_error ("Expected VMDB version %d.%d, got %d.%d. "
                  "Aborting.", 4, 10, vm->ver_major, vm->ver_minor);
            return false;
      }

      vm->vblk_size     = BE32 (data + 0x08);
      vm->vblk_offset   = BE32 (data + 0x0C);
      vm->last_vblk_seq = BE32 (data + 0x04);

      ldm_debug ("Parsed VMDB successfully.");
      return true;
}

/**
 * ldm_compare_privheads - Compare two privhead objects
 * @ph1:  First privhead
 * @ph2:  Second privhead
 *
 * This compares the two privhead structures @ph1 and @ph2.
 *
 * Return:  'true'   Identical
 *          'false'  Different
 */
static bool ldm_compare_privheads (const struct privhead *ph1,
                           const struct privhead *ph2)
{
      BUG_ON (!ph1 || !ph2);

      return ((ph1->ver_major          == ph2->ver_major)         &&
            (ph1->ver_minor          == ph2->ver_minor)           &&
            (ph1->logical_disk_start == ph2->logical_disk_start)  &&
            (ph1->logical_disk_size  == ph2->logical_disk_size)   &&
            (ph1->config_start       == ph2->config_start)        &&
            (ph1->config_size        == ph2->config_size)         &&
            !memcmp (ph1->disk_id, ph2->disk_id, GUID_SIZE));
}

/**
 * ldm_compare_tocblocks - Compare two tocblock objects
 * @toc1:  First toc
 * @toc2:  Second toc
 *
 * This compares the two tocblock structures @toc1 and @toc2.
 *
 * Return:  'true'   Identical
 *          'false'  Different
 */
static bool ldm_compare_tocblocks (const struct tocblock *toc1,
                           const struct tocblock *toc2)
{
      BUG_ON (!toc1 || !toc2);

      return ((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)));
}

/**
 * ldm_validate_privheads - Compare the primary privhead with its backups
 * @bdev:  Device holding the LDM Database
 * @ph1:   Memory struct to fill with ph contents
 *
 * Read and compare all three privheads from disk.
 *
 * The privheads on disk show the size and location of the main disk area and
 * the configuration area (the database).  The values are range-checked against
 * @hd, which contains the real size of the disk.
 *
 * Return:  'true'   Success
 *          'false'  Error
 */
static bool ldm_validate_privheads (struct block_device *bdev,
                            struct privhead *ph1)
{
      static const int off[3] = { OFF_PRIV1, OFF_PRIV2, OFF_PRIV3 };
      struct privhead *ph[3] = { ph1 };
      Sector sect;
      u8 *data;
      bool result = false;
      long num_sects;
      int i;

      BUG_ON (!bdev || !ph1);

      ph[1] = kmalloc (sizeof (*ph[1]), GFP_KERNEL);
      ph[2] = kmalloc (sizeof (*ph[2]), GFP_KERNEL);
      if (!ph[1] || !ph[2]) {
            ldm_crit ("Out of memory.");
            goto out;
      }

      /* off[1 & 2] are relative to ph[0]->config_start */
      ph[0]->config_start = 0;

      /* Read and parse privheads */
      for (i = 0; i < 3; i++) {
            data = read_dev_sector (bdev,
                  ph[0]->config_start + off[i], &sect);
            if (!data) {
                  ldm_crit ("Disk read failed.");
                  goto out;
            }
            result = ldm_parse_privhead (data, ph[i]);
            put_dev_sector (sect);
            if (!result) {
                  ldm_error ("Cannot find PRIVHEAD %d.", i+1); /* Log again */
                  if (i < 2)
                        goto out;   /* Already logged */
                  else
                        break;      /* FIXME ignore for now, 3rd PH can fail on odd-sized disks */
            }
      }

      num_sects = bdev->bd_inode->i_size >> 9;

      if ((ph[0]->config_start > num_sects) ||
         ((ph[0]->config_start + ph[0]->config_size) > num_sects)) {
            ldm_crit ("Database extends beyond the end of the disk.");
            goto out;
      }

      if ((ph[0]->logical_disk_start > ph[0]->config_start) ||
         ((ph[0]->logical_disk_start + ph[0]->logical_disk_size)
                > ph[0]->config_start)) {
            ldm_crit ("Disk and database overlap.");
            goto out;
      }

      if (!ldm_compare_privheads (ph[0], ph[1])) {
            ldm_crit ("Primary and backup PRIVHEADs don't match.");
            goto out;
      }
      /* FIXME ignore this for now
      if (!ldm_compare_privheads (ph[0], ph[2])) {
            ldm_crit ("Primary and backup PRIVHEADs don't match.");
            goto out;
      }*/
      ldm_debug ("Validated PRIVHEADs successfully.");
      result = true;
out:
      kfree (ph[1]);
      kfree (ph[2]);
      return result;
}

/**
 * ldm_validate_tocblocks - Validate the table of contents and its backups
 * @bdev:  Device holding the LDM Database
 * @base:  Offset, into @bdev, of the database
 * @ldb:   Cache of the database structures
 *
 * Find and compare the four tables of contents of the LDM Database stored on
 * @bdev and return the parsed information into @toc1.
 *
 * The offsets and sizes of the configs are range-checked against a privhead.
 *
 * Return:  'true'   @toc1 contains validated TOCBLOCK info
 *          'false'  @toc1 contents are undefined
 */
static bool ldm_validate_tocblocks(struct block_device *bdev,
      unsigned long base, struct ldmdb *ldb)
{
      static const int off[4] = { OFF_TOCB1, OFF_TOCB2, OFF_TOCB3, OFF_TOCB4};
      struct tocblock *tb[4];
      struct privhead *ph;
      Sector sect;
      u8 *data;
      int i, nr_tbs;
      bool result = false;

      BUG_ON(!bdev || !ldb);
      ph = &ldb->ph;
      tb[0] = &ldb->toc;
      tb[1] = kmalloc(sizeof(*tb[1]) * 3, GFP_KERNEL);
      if (!tb[1]) {
            ldm_crit("Out of memory.");
            goto err;
      }
      tb[2] = (struct tocblock*)((u8*)tb[1] + sizeof(*tb[1]));
      tb[3] = (struct tocblock*)((u8*)tb[2] + sizeof(*tb[2]));
      /*
       * Try to read and parse all four TOCBLOCKs.
       *
       * Windows Vista LDM v2.12 does not always have all four TOCBLOCKs so
       * skip any that fail as long as we get at least one valid TOCBLOCK.
       */
      for (nr_tbs = i = 0; i < 4; i++) {
            data = read_dev_sector(bdev, base + off[i], &sect);
            if (!data) {
                  ldm_error("Disk read failed for TOCBLOCK %d.", i);
                  continue;
            }
            if (ldm_parse_tocblock(data, tb[nr_tbs]))
                  nr_tbs++;
            put_dev_sector(sect);
      }
      if (!nr_tbs) {
            ldm_crit("Failed to find a valid TOCBLOCK.");
            goto err;
      }
      /* Range check the TOCBLOCK against a privhead. */
      if (((tb[0]->bitmap1_start + tb[0]->bitmap1_size) > ph->config_size) ||
                  ((tb[0]->bitmap2_start + tb[0]->bitmap2_size) >
                  ph->config_size)) {
            ldm_crit("The bitmaps are out of range.  Giving up.");
            goto err;
      }
      /* Compare all loaded TOCBLOCKs. */
      for (i = 1; i < nr_tbs; i++) {
            if (!ldm_compare_tocblocks(tb[0], tb[i])) {
                  ldm_crit("TOCBLOCKs 0 and %d do not match.", i);
                  goto err;
            }
      }
      ldm_debug("Validated %d TOCBLOCKs successfully.", nr_tbs);
      result = true;
err:
      kfree(tb[1]);
      return result;
}

/**
 * ldm_validate_vmdb - Read the VMDB and validate it
 * @bdev:  Device holding the LDM Database
 * @base:  Offset, into @bdev, of the database
 * @ldb:   Cache of the database structures
 *
 * Find the vmdb of the LDM Database stored on @bdev and return the parsed
 * information in @ldb.
 *
 * Return:  'true'   @ldb contains validated VBDB info
 *          'false'  @ldb contents are undefined
 */
static bool ldm_validate_vmdb (struct block_device *bdev, unsigned long base,
                         struct ldmdb *ldb)
{
      Sector sect;
      u8 *data;
      bool result = false;
      struct vmdb *vm;
      struct tocblock *toc;

      BUG_ON (!bdev || !ldb);

      vm  = &ldb->vm;
      toc = &ldb->toc;

      data = read_dev_sector (bdev, base + OFF_VMDB, &sect);
      if (!data) {
            ldm_crit ("Disk read failed.");
            return false;
      }

      if (!ldm_parse_vmdb (data, vm))
            goto out;                     /* Already logged */

      /* Are there uncommitted transactions? */
      if (BE16(data + 0x10) != 0x01) {
            ldm_crit ("Database is not in a consistent state.  Aborting.");
            goto out;
      }

      if (vm->vblk_offset != 512)
            ldm_info ("VBLKs start at offset 0x%04x.", vm->vblk_offset);

      /*
       * The last_vblkd_seq can be before the end of the vmdb, just make sure
       * it is not out of bounds.
       */
      if ((vm->vblk_size * vm->last_vblk_seq) > (toc->bitmap1_size << 9)) {
            ldm_crit ("VMDB exceeds allowed size specified by TOCBLOCK.  "
                        "Database is corrupt.  Aborting.");
            goto out;
      }

      result = true;
out:
      put_dev_sector (sect);
      return result;
}


/**
 * ldm_validate_partition_table - Determine whether bdev might be a dynamic disk
 * @bdev:  Device holding the LDM Database
 *
 * This function provides a weak test to decide whether the device is a dynamic
 * disk or not.  It looks for an MS-DOS-style partition table containing at
 * least one partition of type 0x42 (formerly SFS, now used by Windows for
 * dynamic disks).
 *
 * N.B.  The only possible error can come from the read_dev_sector and that is
 *       only likely to happen if the underlying device is strange.  If that IS
 *       the case we should return zero to let someone else try.
 *
 * Return:  'true'   @bdev is a dynamic disk
 *          'false'  @bdev is not a dynamic disk, or an error occurred
 */
static bool ldm_validate_partition_table (struct block_device *bdev)
{
      Sector sect;
      u8 *data;
      struct partition *p;
      int i;
      bool result = false;

      BUG_ON (!bdev);

      data = read_dev_sector (bdev, 0, &sect);
      if (!data) {
            ldm_crit ("Disk read failed.");
            return false;
      }

      if (*(__le16*) (data + 0x01FE) != cpu_to_le16 (MSDOS_LABEL_MAGIC))
            goto out;

      p = (struct partition*)(data + 0x01BE);
      for (i = 0; i < 4; i++, p++)
            if (SYS_IND (p) == LDM_PARTITION) {
                  result = true;
                  break;
            }

      if (result)
            ldm_debug ("Found W2K dynamic disk partition type.");

out:
      put_dev_sector (sect);
      return result;
}

/**
 * ldm_get_disk_objid - Search a linked list of vblk's for a given Disk Id
 * @ldb:  Cache of the database structures
 *
 * The LDM Database contains a list of all partitions on all dynamic disks.
 * The primary PRIVHEAD, at the beginning of the physical disk, tells us
 * the GUID of this disk.  This function searches for the GUID in a linked
 * list of vblk's.
 *
 * Return:  Pointer, A matching vblk was found
 *          NULL,    No match, or an error
 */
static struct vblk * ldm_get_disk_objid (const struct ldmdb *ldb)
{
      struct list_head *item;

      BUG_ON (!ldb);

      list_for_each (item, &ldb->v_disk) {
            struct vblk *v = list_entry (item, struct vblk, list);
            if (!memcmp (v->vblk.disk.disk_id, ldb->ph.disk_id, GUID_SIZE))
                  return v;
      }

      return NULL;
}

/**
 * ldm_create_data_partitions - Create data partitions for this device
 * @pp:   List of the partitions parsed so far
 * @ldb:  Cache of the database structures
 *
 * The database contains ALL the partitions for ALL disk groups, 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.
 *
 * Add each partition in our database, to the parsed_partitions structure.
 *
 * N.B.  This function creates the partitions in the order it finds partition
 *       objects in the linked list.
 *
 * Return:  'true'   Partition created
 *          'false'  Error, probably a range checking problem
 */
static bool ldm_create_data_partitions (struct parsed_partitions *pp,
                              const struct ldmdb *ldb)
{
      struct list_head *item;
      struct vblk *vb;
      struct vblk *disk;
      struct vblk_part *part;
      int part_num = 1;

      BUG_ON (!pp || !ldb);

      disk = ldm_get_disk_objid (ldb);
      if (!disk) {
            ldm_crit ("Can't find the ID of this disk in the database.");
            return false;
      }

      printk (" [LDM]");

      /* Create the data partitions */
      list_for_each (item, &ldb->v_part) {
            vb = list_entry (item, struct vblk, list);
            part = &vb->vblk.part;

            if (part->disk_id != disk->obj_id)
                  continue;

            put_partition (pp, part_num, ldb->ph.logical_disk_start +
                        part->start, part->size);
            part_num++;
      }

      printk ("\n");
      return true;
}


/**
 * ldm_relative - Calculate the next relative offset
 * @buffer:  Block of data being worked on
 * @buflen:  Size of the block of data
 * @base:    Size of the previous fixed width fields
 * @offset:  Cumulative size of the previous variable-width fields
 *
 * Because many of the VBLK fields are variable-width, it's necessary
 * to calculate each offset based on the previous one and the length
 * of the field it pointed to.
 *
 * Return:  -1 Error, the calculated offset exceeded the size of the buffer
 *           n OK, a range-checked offset into buffer
 */
static int ldm_relative(const u8 *buffer, int buflen, int base, int offset)
{

      base += offset;
      if (!buffer || offset < 0 || base > buflen) {
            if (!buffer)
                  ldm_error("!buffer");
            if (offset < 0)
                  ldm_error("offset (%d) < 0", offset);
            if (base > buflen)
                  ldm_error("base (%d) > buflen (%d)", base, buflen);
            return -1;
      }
      if (base + buffer[base] >= buflen) {
            ldm_error("base (%d) + buffer[base] (%d) >= buflen (%d)", base,
                        buffer[base], buflen);
            return -1;
      }
      return buffer[base] + offset + 1;
}

/**
 * ldm_get_vnum - Convert a variable-width, big endian number, into cpu order
 * @block:  Pointer to the variable-width number to convert
 *
 * Large numbers in the LDM Database are often stored in a packed format.  Each
 * number is prefixed by a one byte width marker.  All numbers in the database
 * are stored in big-endian byte order.  This function reads one of these
 * numbers and returns the result
 *
 * N.B.  This function DOES NOT perform any range checking, though the most
 *       it will read is eight bytes.
 *
 * Return:  n A number
 *          0 Zero, or an error occurred
 */
static u64 ldm_get_vnum (const u8 *block)
{
      u64 tmp = 0;
      u8 length;

      BUG_ON (!block);

      length = *block++;

      if (length && length <= 8)
            while (length--)
                  tmp = (tmp << 8) | *block++;
      else
            ldm_error ("Illegal length %d.", length);

      return tmp;
}

/**
 * ldm_get_vstr - Read a length-prefixed string into a buffer
 * @block:   Pointer to the length marker
 * @buffer:  Location to copy string to
 * @buflen:  Size of the output buffer
 *
 * Many of the strings in the LDM Database are not NULL terminated.  Instead
 * they are prefixed by a one byte length marker.  This function copies one of
 * these strings into a buffer.
 *
 * N.B.  This function DOES NOT perform any range checking on the input.
 *       If the buffer is too small, the output will be truncated.
 *
 * Return:  0, Error and @buffer contents are undefined
 *          n, String length in characters (excluding NULL)
 *          buflen-1, String was truncated.
 */
static int ldm_get_vstr (const u8 *block, u8 *buffer, int buflen)
{
      int length;

      BUG_ON (!block || !buffer);

      length = block[0];
      if (length >= buflen) {
            ldm_error ("Truncating string %d -> %d.", length, buflen);
            length = buflen - 1;
      }
      memcpy (buffer, block + 1, length);
      buffer[length] = 0;
      return length;
}


/**
 * ldm_parse_cmp3 - Read a raw VBLK Component object into a vblk structure
 * @buffer:  Block of data being worked on
 * @buflen:  Size of the block of data
 * @vb:      In-memory vblk in which to return information
 *
 * Read a raw VBLK Component object (version 3) into a vblk structure.
 *
 * Return:  'true'   @vb contains a Component VBLK
 *          'false'  @vb contents are not defined
 */
static bool ldm_parse_cmp3 (const u8 *buffer, int buflen, struct vblk *vb)
{
      int r_objid, r_name, r_vstate, r_child, r_parent, r_stripe, r_cols, len;
      struct vblk_comp *comp;

      BUG_ON (!buffer || !vb);

      r_objid  = ldm_relative (buffer, buflen, 0x18, 0);
      r_name   = ldm_relative (buffer, buflen, 0x18, r_objid);
      r_vstate = ldm_relative (buffer, buflen, 0x18, r_name);
      r_child  = ldm_relative (buffer, buflen, 0x1D, r_vstate);
      r_parent = ldm_relative (buffer, buflen, 0x2D, r_child);

      if (buffer[0x12] & VBLK_FLAG_COMP_STRIPE) {
            r_stripe = ldm_relative (buffer, buflen, 0x2E, r_parent);
            r_cols   = ldm_relative (buffer, buflen, 0x2E, r_stripe);
            len = r_cols;
      } else {
            r_stripe = 0;
            r_cols   = 0;
            len = r_parent;
      }
      if (len < 0)
            return false;

      len += VBLK_SIZE_CMP3;
      if (len != BE32 (buffer + 0x14))
            return false;

      comp = &vb->vblk.comp;
      ldm_get_vstr (buffer + 0x18 + r_name, comp->state,
            sizeof (comp->state));
      comp->type      = buffer[0x18 + r_vstate];
      comp->children  = ldm_get_vnum (buffer + 0x1D + r_vstate);
      comp->parent_id = ldm_get_vnum (buffer + 0x2D + r_child);
      comp->chunksize = r_stripe ? ldm_get_vnum (buffer+r_parent+0x2E) : 0;

      return true;
}

/**
 * ldm_parse_dgr3 - Read a raw VBLK Disk Group object into a vblk structure
 * @buffer:  Block of data being worked on
 * @buflen:  Size of the block of data
 * @vb:      In-memory vblk in which to return information
 *
 * Read a raw VBLK Disk Group object (version 3) into a vblk structure.
 *
 * Return:  'true'   @vb contains a Disk Group VBLK
 *          'false'  @vb contents are not defined
 */
static int ldm_parse_dgr3 (const u8 *buffer, int buflen, struct vblk *vb)
{
      int r_objid, r_name, r_diskid, r_id1, r_id2, len;
      struct vblk_dgrp *dgrp;

      BUG_ON (!buffer || !vb);

      r_objid  = ldm_relative (buffer, buflen, 0x18, 0);
      r_name   = ldm_relative (buffer, buflen, 0x18, r_objid);
      r_diskid = ldm_relative (buffer, buflen, 0x18, r_name);

      if (buffer[0x12] & VBLK_FLAG_DGR3_IDS) {
            r_id1 = ldm_relative (buffer, buflen, 0x24, r_diskid);
            r_id2 = ldm_relative (buffer, buflen, 0x24, r_id1);
            len = r_id2;
      } else {
            r_id1 = 0;
            r_id2 = 0;
            len = r_diskid;
      }
      if (len < 0)
            return false;

      len += VBLK_SIZE_DGR3;
      if (len != BE32 (buffer + 0x14))
            return false;

      dgrp = &vb->vblk.dgrp;
      ldm_get_vstr (buffer + 0x18 + r_name, dgrp->disk_id,
            sizeof (dgrp->disk_id));
      return true;
}

/**
 * ldm_parse_dgr4 - Read a raw VBLK Disk Group object into a vblk structure
 * @buffer:  Block of data being worked on
 * @buflen:  Size of the block of data
 * @vb:      In-memory vblk in which to return information
 *
 * Read a raw VBLK Disk Group object (version 4) into a vblk structure.
 *
 * Return:  'true'   @vb contains a Disk Group VBLK
 *          'false'  @vb contents are not defined
 */
static bool ldm_parse_dgr4 (const u8 *buffer, int buflen, struct vblk *vb)
{
      char buf[64];
      int r_objid, r_name, r_id1, r_id2, len;
      struct vblk_dgrp *dgrp;

      BUG_ON (!buffer || !vb);

      r_objid  = ldm_relative (buffer, buflen, 0x18, 0);
      r_name   = ldm_relative (buffer, buflen, 0x18, r_objid);

      if (buffer[0x12] & VBLK_FLAG_DGR4_IDS) {
            r_id1 = ldm_relative (buffer, buflen, 0x44, r_name);
            r_id2 = ldm_relative (buffer, buflen, 0x44, r_id1);
            len = r_id2;
      } else {
            r_id1 = 0;
            r_id2 = 0;
            len = r_name;
      }
      if (len < 0)
            return false;

      len += VBLK_SIZE_DGR4;
      if (len != BE32 (buffer + 0x14))
            return false;

      dgrp = &vb->vblk.dgrp;

      ldm_get_vstr (buffer + 0x18 + r_objid, buf, sizeof (buf));
      return true;
}

/**
 * ldm_parse_dsk3 - Read a raw VBLK Disk object into a vblk structure
 * @buffer:  Block of data being worked on
 * @buflen:  Size of the block of data
 * @vb:      In-memory vblk in which to return information
 *
 * Read a raw VBLK Disk object (version 3) into a vblk structure.
 *
 * Return:  'true'   @vb contains a Disk VBLK
 *          'false'  @vb contents are not defined
 */
static bool ldm_parse_dsk3 (const u8 *buffer, int buflen, struct vblk *vb)
{
      int r_objid, r_name, r_diskid, r_altname, len;
      struct vblk_disk *disk;

      BUG_ON (!buffer || !vb);

      r_objid   = ldm_relative (buffer, buflen, 0x18, 0);
      r_name    = ldm_relative (buffer, buflen, 0x18, r_objid);
      r_diskid  = ldm_relative (buffer, buflen, 0x18, r_name);
      r_altname = ldm_relative (buffer, buflen, 0x18, r_diskid);
      len = r_altname;
      if (len < 0)
            return false;

      len += VBLK_SIZE_DSK3;
      if (len != BE32 (buffer + 0x14))
            return false;

      disk = &vb->vblk.disk;
      ldm_get_vstr (buffer + 0x18 + r_diskid, disk->alt_name,
            sizeof (disk->alt_name));
      if (!ldm_parse_guid (buffer + 0x19 + r_name, disk->disk_id))
            return false;

      return true;
}

/**
 * ldm_parse_dsk4 - Read a raw VBLK Disk object into a vblk structure
 * @buffer:  Block of data being worked on
 * @buflen:  Size of the block of data
 * @vb:      In-memory vblk in which to return information
 *
 * Read a raw VBLK Disk object (version 4) into a vblk structure.
 *
 * Return:  'true'   @vb contains a Disk VBLK
 *          'false'  @vb contents are not defined
 */
static bool ldm_parse_dsk4 (const u8 *buffer, int buflen, struct vblk *vb)
{
      int r_objid, r_name, len;
      struct vblk_disk *disk;

      BUG_ON (!buffer || !vb);

      r_objid = ldm_relative (buffer, buflen, 0x18, 0);
      r_name  = ldm_relative (buffer, buflen, 0x18, r_objid);
      len     = r_name;
      if (len < 0)
            return false;

      len += VBLK_SIZE_DSK4;
      if (len != BE32 (buffer + 0x14))
            return false;

      disk = &vb->vblk.disk;
      memcpy (disk->disk_id, buffer + 0x18 + r_name, GUID_SIZE);
      return true;
}

/**
 * ldm_parse_prt3 - Read a raw VBLK Partition object into a vblk structure
 * @buffer:  Block of data being worked on
 * @buflen:  Size of the block of data
 * @vb:      In-memory vblk in which to return information
 *
 * Read a raw VBLK Partition object (version 3) into a vblk structure.
 *
 * Return:  'true'   @vb contains a Partition VBLK
 *          'false'  @vb contents are not defined
 */
static bool ldm_parse_prt3(const u8 *buffer, int buflen, struct vblk *vb)
{
      int r_objid, r_name, r_size, r_parent, r_diskid, r_index, len;
      struct vblk_part *part;

      BUG_ON(!buffer || !vb);
      r_objid = ldm_relative(buffer, buflen, 0x18, 0);
      if (r_objid < 0) {
            ldm_error("r_objid %d < 0", r_objid);
            return false;
      }
      r_name = ldm_relative(buffer, buflen, 0x18, r_objid);
      if (r_name < 0) {
            ldm_error("r_name %d < 0", r_name);
            return false;
      }
      r_size = ldm_relative(buffer, buflen, 0x34, r_name);
      if (r_size < 0) {
            ldm_error("r_size %d < 0", r_size);
            return false;
      }
      r_parent = ldm_relative(buffer, buflen, 0x34, r_size);
      if (r_parent < 0) {
            ldm_error("r_parent %d < 0", r_parent);
            return false;
      }
      r_diskid = ldm_relative(buffer, buflen, 0x34, r_parent);
      if (r_diskid < 0) {
            ldm_error("r_diskid %d < 0", r_diskid);
            return false;
      }
      if (buffer[0x12] & VBLK_FLAG_PART_INDEX) {
            r_index = ldm_relative(buffer, buflen, 0x34, r_diskid);
            if (r_index < 0) {
                  ldm_error("r_index %d < 0", r_index);
                  return false;
            }
            len = r_index;
      } else {
            r_index = 0;
            len = r_diskid;
      }
      if (len < 0) {
            ldm_error("len %d < 0", len);
            return false;
      }
      len += VBLK_SIZE_PRT3;
      if (len > BE32(buffer + 0x14)) {
            ldm_error("len %d > BE32(buffer + 0x14) %d", len,
                        BE32(buffer + 0x14));
            return false;
      }
      part = &vb->vblk.part;
      part->start = BE64(buffer + 0x24 + r_name);
      part->volume_offset = BE64(buffer + 0x2C + r_name);
      part->size = ldm_get_vnum(buffer + 0x34 + r_name);
      part->parent_id = ldm_get_vnum(buffer + 0x34 + r_size);
      part->disk_id = ldm_get_vnum(buffer + 0x34 + r_parent);
      if (vb->flags & VBLK_FLAG_PART_INDEX)
            part->partnum = buffer[0x35 + r_diskid];
      else
            part->partnum = 0;
      return true;
}

/**
 * ldm_parse_vol5 - Read a raw VBLK Volume object into a vblk structure
 * @buffer:  Block of data being worked on
 * @buflen:  Size of the block of data
 * @vb:      In-memory vblk in which to return information
 *
 * Read a raw VBLK Volume object (version 5) into a vblk structure.
 *
 * Return:  'true'   @vb contains a Volume VBLK
 *          'false'  @vb contents are not defined
 */
static bool ldm_parse_vol5(const u8 *buffer, int buflen, struct vblk *vb)
{
      int r_objid, r_name, r_vtype, r_disable_drive_letter, r_child, r_size;
      int r_id1, r_id2, r_size2, r_drive, len;
      struct vblk_volu *volu;

      BUG_ON(!buffer || !vb);
      r_objid = ldm_relative(buffer, buflen, 0x18, 0);
      if (r_objid < 0) {
            ldm_error("r_objid %d < 0", r_objid);
            return false;
      }
      r_name = ldm_relative(buffer, buflen, 0x18, r_objid);
      if (r_name < 0) {
            ldm_error("r_name %d < 0", r_name);
            return false;
      }
      r_vtype = ldm_relative(buffer, buflen, 0x18, r_name);
      if (r_vtype < 0) {
            ldm_error("r_vtype %d < 0", r_vtype);
            return false;
      }
      r_disable_drive_letter = ldm_relative(buffer, buflen, 0x18, r_vtype);
      if (r_disable_drive_letter < 0) {
            ldm_error("r_disable_drive_letter %d < 0",
                        r_disable_drive_letter);
            return false;
      }
      r_child = ldm_relative(buffer, buflen, 0x2D, r_disable_drive_letter);
      if (r_child < 0) {
            ldm_error("r_child %d < 0", r_child);
            return false;
      }
      r_size = ldm_relative(buffer, buflen, 0x3D, r_child);
      if (r_size < 0) {
            ldm_error("r_size %d < 0", r_size);
            return false;
      }
      if (buffer[0x12] & VBLK_FLAG_VOLU_ID1) {
            r_id1 = ldm_relative(buffer, buflen, 0x52, r_size);
            if (r_id1 < 0) {
                  ldm_error("r_id1 %d < 0", r_id1);
                  return false;
            }
      } else
            r_id1 = r_size;
      if (buffer[0x12] & VBLK_FLAG_VOLU_ID2) {
            r_id2 = ldm_relative(buffer, buflen, 0x52, r_id1);
            if (r_id2 < 0) {
                  ldm_error("r_id2 %d < 0", r_id2);
                  return false;
            }
      } else
            r_id2 = r_id1;
      if (buffer[0x12] & VBLK_FLAG_VOLU_SIZE) {
            r_size2 = ldm_relative(buffer, buflen, 0x52, r_id2);
            if (r_size2 < 0) {
                  ldm_error("r_size2 %d < 0", r_size2);
                  return false;
            }
      } else
            r_size2 = r_id2;
      if (buffer[0x12] & VBLK_FLAG_VOLU_DRIVE) {
            r_drive = ldm_relative(buffer, buflen, 0x52, r_size2);
            if (r_drive < 0) {
                  ldm_error("r_drive %d < 0", r_drive);
                  return false;
            }
      } else
            r_drive = r_size2;
      len = r_drive;
      if (len < 0) {
            ldm_error("len %d < 0", len);
            return false;
      }
      len += VBLK_SIZE_VOL5;
      if (len > BE32(buffer + 0x14)) {
            ldm_error("len %d > BE32(buffer + 0x14) %d", len,
                        BE32(buffer + 0x14));
            return false;
      }
      volu = &vb->vblk.volu;
      ldm_get_vstr(buffer + 0x18 + r_name, volu->volume_type,
                  sizeof(volu->volume_type));
      memcpy(volu->volume_state, buffer + 0x18 + r_disable_drive_letter,
                  sizeof(volu->volume_state));
      volu->size = ldm_get_vnum(buffer + 0x3D + r_child);
      volu->partition_type = buffer[0x41 + r_size];
      memcpy(volu->guid, buffer + 0x42 + r_size, sizeof(volu->guid));
      if (buffer[0x12] & VBLK_FLAG_VOLU_DRIVE) {
            ldm_get_vstr(buffer + 0x52 + r_size, volu->drive_hint,
                        sizeof(volu->drive_hint));
      }
      return true;
}

/**
 * ldm_parse_vblk - Read a raw VBLK object into a vblk structure
 * @buf:  Block of data being worked on
 * @len:  Size of the block of data
 * @vb:   In-memory vblk in which to return information
 *
 * Read a raw VBLK object into a vblk structure.  This function just reads the
 * information common to all VBLK types, then delegates the rest of the work to
 * helper functions: ldm_parse_*.
 *
 * Return:  'true'   @vb contains a VBLK
 *          'false'  @vb contents are not defined
 */
static bool ldm_parse_vblk (const u8 *buf, int len, struct vblk *vb)
{
      bool result = false;
      int r_objid;

      BUG_ON (!buf || !vb);

      r_objid = ldm_relative (buf, len, 0x18, 0);
      if (r_objid < 0) {
            ldm_error ("VBLK header is corrupt.");
            return false;
      }

      vb->flags  = buf[0x12];
      vb->type   = buf[0x13];
      vb->obj_id = ldm_get_vnum (buf + 0x18);
      ldm_get_vstr (buf+0x18+r_objid, vb->name, sizeof (vb->name));

      switch (vb->type) {
            case VBLK_CMP3:  result = ldm_parse_cmp3 (buf, len, vb); break;
            case VBLK_DSK3:  result = ldm_parse_dsk3 (buf, len, vb); break;
            case VBLK_DSK4:  result = ldm_parse_dsk4 (buf, len, vb); break;
            case VBLK_DGR3:  result = ldm_parse_dgr3 (buf, len, vb); break;
            case VBLK_DGR4:  result = ldm_parse_dgr4 (buf, len, vb); break;
            case VBLK_PRT3:  result = ldm_parse_prt3 (buf, len, vb); break;
            case VBLK_VOL5:  result = ldm_parse_vol5 (buf, len, vb); break;
      }

      if (result)
            ldm_debug ("Parsed VBLK 0x%llx (type: 0x%02x) ok.",
                   (unsigned long long) vb->obj_id, vb->type);
      else
            ldm_error ("Failed to parse VBLK 0x%llx (type: 0x%02x).",
                  (unsigned long long) vb->obj_id, vb->type);

      return result;
}


/**
 * ldm_ldmdb_add - Adds a raw VBLK entry to the ldmdb database
 * @data:  Raw VBLK to add to the database
 * @len:   Size of the raw VBLK
 * @ldb:   Cache of the database structures
 *
 * The VBLKs are sorted into categories.  Partitions are also sorted by offset.
 *
 * N.B.  This function does not check the validity of the VBLKs.
 *
 * Return:  'true'   The VBLK was added
 *          'false'  An error occurred
 */
static bool ldm_ldmdb_add (u8 *data, int len, struct ldmdb *ldb)
{
      struct vblk *vb;
      struct list_head *item;

      BUG_ON (!data || !ldb);

      vb = kmalloc (sizeof (*vb), GFP_KERNEL);
      if (!vb) {
            ldm_crit ("Out of memory.");
            return false;
      }

      if (!ldm_parse_vblk (data, len, vb)) {
            kfree(vb);
            return false;                 /* Already logged */
      }

      /* Put vblk into the correct list. */
      switch (vb->type) {
      case VBLK_DGR3:
      case VBLK_DGR4:
            list_add (&vb->list, &ldb->v_dgrp);
            break;
      case VBLK_DSK3:
      case VBLK_DSK4:
            list_add (&vb->list, &ldb->v_disk);
            break;
      case VBLK_VOL5:
            list_add (&vb->list, &ldb->v_volu);
            break;
      case VBLK_CMP3:
            list_add (&vb->list, &ldb->v_comp);
            break;
      case VBLK_PRT3:
            /* Sort by the partition's start sector. */
            list_for_each (item, &ldb->v_part) {
                  struct vblk *v = list_entry (item, struct vblk, list);
                  if ((v->vblk.part.disk_id == vb->vblk.part.disk_id) &&
                      (v->vblk.part.start > vb->vblk.part.start)) {
                        list_add_tail (&vb->list, &v->list);
                        return true;
                  }
            }
            list_add_tail (&vb->list, &ldb->v_part);
            break;
      }
      return true;
}

/**
 * ldm_frag_add - Add a VBLK fragment to a list
 * @data:   Raw fragment to be added to the list
 * @size:   Size of the raw fragment
 * @frags:  Linked list of VBLK fragments
 *
 * Fragmented VBLKs may not be consecutive in the database, so they are placed
 * in a list so they can be pieced together later.
 *
 * Return:  'true'   Success, the VBLK was added to the list
 *          'false'  Error, a problem occurred
 */
static bool ldm_frag_add (const u8 *data, int size, struct list_head *frags)
{
      struct frag *f;
      struct list_head *item;
      int rec, num, group;

      BUG_ON (!data || !frags);

      group = BE32 (data + 0x08);
      rec   = BE16 (data + 0x0C);
      num   = BE16 (data + 0x0E);
      if ((num < 1) || (num > 4)) {
            ldm_error ("A VBLK claims to have %d parts.", num);
            return false;
      }

      list_for_each (item, frags) {
            f = list_entry (item, struct frag, list);
            if (f->group == group)
                  goto found;
      }

      f = kmalloc (sizeof (*f) + size*num, GFP_KERNEL);
      if (!f) {
            ldm_crit ("Out of memory.");
            return false;
      }

      f->group = group;
      f->num   = num;
      f->rec   = rec;
      f->map   = 0xFF << num;

      list_add_tail (&f->list, frags);
found:
      if (f->map & (1 << rec)) {
            ldm_error ("Duplicate VBLK, part %d.", rec);
            f->map &= 0x7F;               /* Mark the group as broken */
            return false;
      }

      f->map |= (1 << rec);

      if (num > 0) {
            data += VBLK_SIZE_HEAD;
            size -= VBLK_SIZE_HEAD;
      }
      memcpy (f->data+rec*(size-VBLK_SIZE_HEAD)+VBLK_SIZE_HEAD, data, size);

      return true;
}

/**
 * ldm_frag_free - Free a linked list of VBLK fragments
 * @list:  Linked list of fragments
 *
 * Free a linked list of VBLK fragments
 *
 * Return:  none
 */
static void ldm_frag_free (struct list_head *list)
{
      struct list_head *item, *tmp;

      BUG_ON (!list);

      list_for_each_safe (item, tmp, list)
            kfree (list_entry (item, struct frag, list));
}

/**
 * ldm_frag_commit - Validate fragmented VBLKs and add them to the database
 * @frags:  Linked list of VBLK fragments
 * @ldb:    Cache of the database structures
 *
 * Now that all the fragmented VBLKs have been collected, they must be added to
 * the database for later use.
 *
 * Return:  'true'   All the fragments we added successfully
 *          'false'  One or more of the fragments we invalid
 */
static bool ldm_frag_commit (struct list_head *frags, struct ldmdb *ldb)
{
      struct frag *f;
      struct list_head *item;

      BUG_ON (!frags || !ldb);

      list_for_each (item, frags) {
            f = list_entry (item, struct frag, list);

            if (f->map != 0xFF) {
                  ldm_error ("VBLK group %d is incomplete (0x%02x).",
                        f->group, f->map);
                  return false;
            }

            if (!ldm_ldmdb_add (f->data, f->num*ldb->vm.vblk_size, ldb))
                  return false;           /* Already logged */
      }
      return true;
}

/**
 * ldm_get_vblks - Read the on-disk database of VBLKs into memory
 * @bdev:  Device holding the LDM Database
 * @base:  Offset, into @bdev, of the database
 * @ldb:   Cache of the database structures
 *
 * To use the information from the VBLKs, they need to be read from the disk,
 * unpacked and validated.  We cache them in @ldb according to their type.
 *
 * Return:  'true'   All the VBLKs were read successfully
 *          'false'  An error occurred
 */
static bool ldm_get_vblks (struct block_device *bdev, unsigned long base,
                     struct ldmdb *ldb)
{
      int size, perbuf, skip, finish, s, v, recs;
      u8 *data = NULL;
      Sector sect;
      bool result = false;
      LIST_HEAD (frags);

      BUG_ON (!bdev || !ldb);

      size   = ldb->vm.vblk_size;
      perbuf = 512 / size;
      skip   = ldb->vm.vblk_offset >> 9;        /* Bytes to sectors */
      finish = (size * ldb->vm.last_vblk_seq) >> 9;

      for (s = skip; s < finish; s++) {         /* For each sector */
            data = read_dev_sector (bdev, base + OFF_VMDB + s, &sect);
            if (!data) {
                  ldm_crit ("Disk read failed.");
                  goto out;
            }

            for (v = 0; v < perbuf; v++, data+=size) {  /* For each vblk */
                  if (MAGIC_VBLK != BE32 (data)) {
                        ldm_error ("Expected to find a VBLK.");
                        goto out;
                  }

                  recs = BE16 (data + 0x0E);    /* Number of records */
                  if (recs == 1) {
                        if (!ldm_ldmdb_add (data, size, ldb))
                              goto out;   /* Already logged */
                  } else if (recs > 1) {
                        if (!ldm_frag_add (data, size, &frags))
                              goto out;   /* Already logged */
                  }
                  /* else Record is not in use, ignore it. */
            }
            put_dev_sector (sect);
            data = NULL;
      }

      result = ldm_frag_commit (&frags, ldb);   /* Failures, already logged */
out:
      if (data)
            put_dev_sector (sect);
      ldm_frag_free (&frags);

      return result;
}

/**
 * ldm_free_vblks - Free a linked list of vblk's
 * @lh:  Head of a linked list of struct vblk
 *
 * Free a list of vblk's and free the memory used to maintain the list.
 *
 * Return:  none
 */
static void ldm_free_vblks (struct list_head *lh)
{
      struct list_head *item, *tmp;

      BUG_ON (!lh);

      list_for_each_safe (item, tmp, lh)
            kfree (list_entry (item, struct vblk, list));
}


/**
 * ldm_partition - Find out whether a device is a dynamic disk and handle it
 * @pp:    List of the partitions parsed so far
 * @bdev:  Device holding the LDM Database
 *
 * This determines whether the device @bdev is a dynamic disk and if so creates
 * the partitions necessary in the gendisk structure pointed to by @hd.
 *
 * We create a dummy device 1, which contains the LDM database, and then create
 * each partition described by the LDM database in sequence as devices 2+. For
 * example, if the device is hda, we would have: hda1: LDM database, hda2, hda3,
 * and so on: the actual data containing partitions.
 *
 * Return:  1 Success, @bdev is a dynamic disk and we handled it
 *          0 Success, @bdev is not a dynamic disk
 *         -1 An error occurred before enough information had been read
 *            Or @bdev is a dynamic disk, but it may be corrupted
 */
int ldm_partition (struct parsed_partitions *pp, struct block_device *bdev)
{
      struct ldmdb  *ldb;
      unsigned long base;
      int result = -1;

      BUG_ON (!pp || !bdev);

      /* Look for signs of a Dynamic Disk */
      if (!ldm_validate_partition_table (bdev))
            return 0;

      ldb = kmalloc (sizeof (*ldb), GFP_KERNEL);
      if (!ldb) {
            ldm_crit ("Out of memory.");
            goto out;
      }

      /* Parse and check privheads. */
      if (!ldm_validate_privheads (bdev, &ldb->ph))
            goto out;         /* Already logged */

      /* All further references are relative to base (database start). */
      base = ldb->ph.config_start;

      /* Parse and check tocs and vmdb. */
      if (!ldm_validate_tocblocks (bdev, base, ldb) ||
          !ldm_validate_vmdb      (bdev, base, ldb))
            goto out;         /* Already logged */

      /* Initialize vblk lists in ldmdb struct */
      INIT_LIST_HEAD (&ldb->v_dgrp);
      INIT_LIST_HEAD (&ldb->v_disk);
      INIT_LIST_HEAD (&ldb->v_volu);
      INIT_LIST_HEAD (&ldb->v_comp);
      INIT_LIST_HEAD (&ldb->v_part);

      if (!ldm_get_vblks (bdev, base, ldb)) {
            ldm_crit ("Failed to read the VBLKs from the database.");
            goto cleanup;
      }

      /* Finally, create the data partition devices. */
      if (ldm_create_data_partitions (pp, ldb)) {
            ldm_debug ("Parsed LDM database successfully.");
            result = 1;
      }
      /* else Already logged */

cleanup:
      ldm_free_vblks (&ldb->v_dgrp);
      ldm_free_vblks (&ldb->v_disk);
      ldm_free_vblks (&ldb->v_volu);
      ldm_free_vblks (&ldb->v_comp);
      ldm_free_vblks (&ldb->v_part);
out:
      kfree (ldb);
      return result;
}

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