grub-lakitu/grub-core/kern/disk.c - cos/cobble - Git at Google

 /*
  *  GRUB  --  GRand Unified Bootloader
  *  Copyright (C) 2002,2003,2004,2006,2007,2008,2009,2010  Free Software Foundation, Inc.
  *
  *  GRUB 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 3 of the License, or
  *  (at your option) any later version.
  *
  *  GRUB 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 GRUB.  If not, see <http://www.gnu.org/licenses/>.
  */

 #include <grub/disk.h>
 #include <grub/err.h>
 #include <grub/mm.h>
 #include <grub/types.h>
 #include <grub/partition.h>
 #include <grub/misc.h>
 #include <grub/time.h>
 #include <grub/file.h>
 #include <grub/i18n.h>

 #define	GRUB_CACHE_TIMEOUT	2

 /* The last time the disk was used.  */
 static grub_uint64_t grub_last_time = 0;

 struct grub_disk_cache grub_disk_cache_table[GRUB_DISK_CACHE_NUM];

 void (*grub_disk_firmware_fini) (void);
 int grub_disk_firmware_is_tainted;

 #if DISK_CACHE_STATS
 static unsigned long grub_disk_cache_hits;
 static unsigned long grub_disk_cache_misses;

 void
 grub_disk_cache_get_performance (unsigned long *hits, unsigned long *misses)
 {
   *hits = grub_disk_cache_hits;
   *misses = grub_disk_cache_misses;
 }
 #endif

 grub_err_t (*grub_disk_write_weak) (grub_disk_t disk,
 				    grub_disk_addr_t sector,
 				    grub_off_t offset,
 				    grub_size_t size,
 				    const void *buf);
 #include "disk_common.c"

 void
 grub_disk_cache_invalidate_all (void)
 {
   unsigned i;

   for (i = 0; i < GRUB_DISK_CACHE_NUM; i++)
     {
       struct grub_disk_cache *cache = grub_disk_cache_table + i;

       if (cache->data && ! cache->lock)
 	{
 	  grub_free (cache->data);
 	  cache->data = 0;
 	}
     }
 }

 static char *
 grub_disk_cache_fetch (unsigned long dev_id, unsigned long disk_id,
 		       grub_disk_addr_t sector)
 {
   struct grub_disk_cache *cache;
   unsigned cache_index;

   cache_index = grub_disk_cache_get_index (dev_id, disk_id, sector);
   cache = grub_disk_cache_table + cache_index;

   if (cache->dev_id == dev_id && cache->disk_id == disk_id
       && cache->sector == sector)
     {
       cache->lock = 1;
 #if DISK_CACHE_STATS
       grub_disk_cache_hits++;
 #endif
       return cache->data;
     }

 #if DISK_CACHE_STATS
   grub_disk_cache_misses++;
 #endif

   return 0;
 }

 static void
 grub_disk_cache_unlock (unsigned long dev_id, unsigned long disk_id,
 			grub_disk_addr_t sector)
 {
   struct grub_disk_cache *cache;
   unsigned cache_index;

   cache_index = grub_disk_cache_get_index (dev_id, disk_id, sector);
   cache = grub_disk_cache_table + cache_index;

   if (cache->dev_id == dev_id && cache->disk_id == disk_id
       && cache->sector == sector)
     cache->lock = 0;
 }

 static grub_err_t
 grub_disk_cache_store (unsigned long dev_id, unsigned long disk_id,
 		       grub_disk_addr_t sector, const char *data)
 {
   unsigned cache_index;
   struct grub_disk_cache *cache;

   cache_index = grub_disk_cache_get_index (dev_id, disk_id, sector);
   cache = grub_disk_cache_table + cache_index;

   cache->lock = 1;
   grub_free (cache->data);
   cache->data = 0;
   cache->lock = 0;

   cache->data = grub_malloc (GRUB_DISK_SECTOR_SIZE << GRUB_DISK_CACHE_BITS);
   if (! cache->data)
     return grub_errno;

   grub_memcpy (cache->data, data,
 	       GRUB_DISK_SECTOR_SIZE << GRUB_DISK_CACHE_BITS);
   cache->dev_id = dev_id;
   cache->disk_id = disk_id;
   cache->sector = sector;

   return GRUB_ERR_NONE;
 }


 grub_disk_dev_t grub_disk_dev_list;

 void
 grub_disk_dev_register (grub_disk_dev_t dev)
 {
   dev->next = grub_disk_dev_list;
   grub_disk_dev_list = dev;
 }

 void
 grub_disk_dev_unregister (grub_disk_dev_t dev)
 {
   grub_disk_dev_t *p, q;

   for (p = &grub_disk_dev_list, q = *p; q; p = &(q->next), q = q->next)
     if (q == dev)
       {
         *p = q->next;
 	break;
       }
 }

 /* Return the location of the first ',', if any, which is not
    escaped by a '\'.  */
 static const char *
 find_part_sep (const char *name)
 {
   const char *p = name;
   char c;

   while ((c = *p++) != '\0')
     {
       if (c == '\\' && *p == ',')
 	p++;
       else if (c == ',')
 	return p - 1;
     }
   return NULL;
 }

 grub_disk_t
 grub_disk_open (const char *name)
 {
   const char *p;
   grub_disk_t disk;
   grub_disk_dev_t dev;
   char *raw = (char *) name;
   grub_uint64_t current_time;

   grub_dprintf ("disk", "Opening `%s'...\n", name);

   disk = (grub_disk_t) grub_zalloc (sizeof (*disk));
   if (! disk)
     return 0;
   disk->log_sector_size = GRUB_DISK_SECTOR_BITS;
   /* Default 1MiB of maximum agglomerate.  */
   disk->max_agglomerate = 1048576 >> (GRUB_DISK_SECTOR_BITS
 				      + GRUB_DISK_CACHE_BITS);

   p = find_part_sep (name);
   if (p)
     {
       grub_size_t len = p - name;

       raw = grub_malloc (len + 1);
       if (! raw)
 	goto fail;

       grub_memcpy (raw, name, len);
       raw[len] = '\0';
       disk->name = grub_strdup (raw);
     }
   else
     disk->name = grub_strdup (name);
   if (! disk->name)
     goto fail;

   for (dev = grub_disk_dev_list; dev; dev = dev->next)
     {
       if ((dev->open) (raw, disk) == GRUB_ERR_NONE)
 	break;
       else if (grub_errno == GRUB_ERR_UNKNOWN_DEVICE)
 	grub_errno = GRUB_ERR_NONE;
       else
 	goto fail;
     }

   if (! dev)
     {
       grub_error (GRUB_ERR_UNKNOWN_DEVICE, N_("disk `%s' not found"),
 		  name);
       goto fail;
     }
   if (disk->log_sector_size > GRUB_DISK_CACHE_BITS + GRUB_DISK_SECTOR_BITS
       || disk->log_sector_size < GRUB_DISK_SECTOR_BITS)
     {
       grub_error (GRUB_ERR_NOT_IMPLEMENTED_YET,
 		  "sector sizes of %d bytes aren't supported yet",
 		  (1 << disk->log_sector_size));
       goto fail;
     }

   disk->dev = dev;

   if (p)
     {
       disk->partition = grub_partition_probe (disk, p + 1);
       if (! disk->partition)
 	{
 	  /* TRANSLATORS: It means that the specified partition e.g.
 	     hd0,msdos1=/dev/sda1 doesn't exist.  */
 	  grub_error (GRUB_ERR_UNKNOWN_DEVICE, N_("no such partition"));
 	  goto fail;
 	}
     }

   /* The cache will be invalidated about 2 seconds after a device was
      closed.  */
   current_time = grub_get_time_ms ();

   if (current_time > (grub_last_time
 		      + GRUB_CACHE_TIMEOUT * 1000))
     grub_disk_cache_invalidate_all ();

   grub_last_time = current_time;

  fail:

   if (raw && raw != name)
     grub_free (raw);

   if (grub_errno != GRUB_ERR_NONE)
     {
       grub_error_push ();
       grub_dprintf ("disk", "Opening `%s' failed.\n", name);
       grub_error_pop ();

       grub_disk_close (disk);
       return 0;
     }

   return disk;
 }

 void
 grub_disk_close (grub_disk_t disk)
 {
   grub_partition_t part;
   grub_dprintf ("disk", "Closing `%s'.\n", disk->name);

   if (disk->dev && disk->dev->close)
     (disk->dev->close) (disk);

   /* Reset the timer.  */
   grub_last_time = grub_get_time_ms ();

   while (disk->partition)
     {
       part = disk->partition->parent;
       grub_free (disk->partition);
       disk->partition = part;
     }
   grub_free ((void *) disk->name);
   grub_free (disk);
 }

 /* Small read (less than cache size and not pass across cache unit boundaries).
    sector is already adjusted and is divisible by cache unit size.
  */
 static grub_err_t
 grub_disk_read_small_real (grub_disk_t disk, grub_disk_addr_t sector,
 			   grub_off_t offset, grub_size_t size, void *buf)
 {
   char *data;
   char *tmp_buf;

   /* Fetch the cache.  */
   data = grub_disk_cache_fetch (disk->dev->id, disk->id, sector);
   if (data)
     {
       /* Just copy it!  */
       grub_memcpy (buf, data + offset, size);
       grub_disk_cache_unlock (disk->dev->id, disk->id, sector);
       return GRUB_ERR_NONE;
     }

   /* Allocate a temporary buffer.  */
   tmp_buf = grub_malloc (GRUB_DISK_SECTOR_SIZE << GRUB_DISK_CACHE_BITS);
   if (! tmp_buf)
     return grub_errno;

   /* Otherwise read data from the disk actually.  */
   if (disk->total_sectors == GRUB_DISK_SIZE_UNKNOWN
       || sector + GRUB_DISK_CACHE_SIZE
       < (disk->total_sectors << (disk->log_sector_size - GRUB_DISK_SECTOR_BITS)))
     {
       grub_err_t err;
       err = (disk->dev->read) (disk, transform_sector (disk, sector),
 			       1U << (GRUB_DISK_CACHE_BITS
 				      + GRUB_DISK_SECTOR_BITS
 				      - disk->log_sector_size), tmp_buf);
       if (!err)
 	{
 	  /* Copy it and store it in the disk cache.  */
 	  grub_memcpy (buf, tmp_buf + offset, size);
 	  grub_disk_cache_store (disk->dev->id, disk->id,
 				 sector, tmp_buf);
 	  grub_free (tmp_buf);
 	  return GRUB_ERR_NONE;
 	}
     }

   grub_free (tmp_buf);
   grub_errno = GRUB_ERR_NONE;

   {
     /* Uggh... Failed. Instead, just read necessary data.  */
     unsigned num;
     grub_disk_addr_t aligned_sector;

     sector += (offset >> GRUB_DISK_SECTOR_BITS);
     offset &= ((1 << GRUB_DISK_SECTOR_BITS) - 1);
     aligned_sector = (sector & ~((1ULL << (disk->log_sector_size
 					   - GRUB_DISK_SECTOR_BITS))
 				 - 1));
     offset += ((sector - aligned_sector) << GRUB_DISK_SECTOR_BITS);
     num = ((size + offset + (1ULL << (disk->log_sector_size))
 	    - 1) >> (disk->log_sector_size));

     tmp_buf = grub_malloc (num << disk->log_sector_size);
     if (!tmp_buf)
       return grub_errno;

     if ((disk->dev->read) (disk, transform_sector (disk, aligned_sector),
 			   num, tmp_buf))
       {
 	grub_error_push ();
 	grub_dprintf ("disk", "%s read failed\n", disk->name);
 	grub_error_pop ();
 	grub_free (tmp_buf);
 	return grub_errno;
       }
     grub_memcpy (buf, tmp_buf + offset, size);
     grub_free (tmp_buf);
     return GRUB_ERR_NONE;
   }
 }

 static grub_err_t
 grub_disk_read_small (grub_disk_t disk, grub_disk_addr_t sector,
 		      grub_off_t offset, grub_size_t size, void *buf)
 {
   grub_err_t err;

   err = grub_disk_read_small_real (disk, sector, offset, size, buf);
   if (err)
     return err;
   if (disk->read_hook)
     (disk->read_hook) (sector + (offset >> GRUB_DISK_SECTOR_BITS),
 		       offset & (GRUB_DISK_SECTOR_SIZE - 1),
 		       size, disk->read_hook_data);
   return GRUB_ERR_NONE;
 }

 /* Read data from the disk.  */
 grub_err_t
 grub_disk_read (grub_disk_t disk, grub_disk_addr_t sector,
 		grub_off_t offset, grub_size_t size, void *buf)
 {
   /* First of all, check if the region is within the disk.  */
   if (grub_disk_adjust_range (disk, &sector, &offset, size) != GRUB_ERR_NONE)
     {
       grub_error_push ();
       grub_dprintf ("disk", "Read out of range: sector 0x%llx (%s).\n",
 		    (unsigned long long) sector, grub_errmsg);
       grub_error_pop ();
       return grub_errno;
     }

   /* First read until first cache boundary.   */
   if (offset || (sector & (GRUB_DISK_CACHE_SIZE - 1)))
     {
       grub_disk_addr_t start_sector;
       grub_size_t pos;
       grub_err_t err;
       grub_size_t len;

       start_sector = sector & ~((grub_disk_addr_t) GRUB_DISK_CACHE_SIZE - 1);
       pos = (sector - start_sector) << GRUB_DISK_SECTOR_BITS;
       len = ((GRUB_DISK_SECTOR_SIZE << GRUB_DISK_CACHE_BITS)
 	     - pos - offset);
       if (len > size)
 	len = size;
       err = grub_disk_read_small (disk, start_sector,
 				  offset + pos, len, buf);
       if (err)
 	return err;
       buf = (char *) buf + len;
       size -= len;
       offset += len;
       sector += (offset >> GRUB_DISK_SECTOR_BITS);
       offset &= ((1 << GRUB_DISK_SECTOR_BITS) - 1);
     }

   /* Until SIZE is zero...  */
   while (size >= (GRUB_DISK_CACHE_SIZE << GRUB_DISK_SECTOR_BITS))
     {
       char *data = NULL;
       grub_disk_addr_t agglomerate;
       grub_err_t err;

       /* agglomerate read until we find a first cached entry.  */
       for (agglomerate = 0; agglomerate
 	     < (size >> (GRUB_DISK_SECTOR_BITS + GRUB_DISK_CACHE_BITS))
 	     && agglomerate < disk->max_agglomerate;
 	   agglomerate++)
 	{
 	  data = grub_disk_cache_fetch (disk->dev->id, disk->id,
 					sector + (agglomerate
 						  << GRUB_DISK_CACHE_BITS));
 	  if (data)
 	    break;
 	}

       if (data)
 	{
 	  grub_memcpy ((char *) buf
 		       + (agglomerate << (GRUB_DISK_CACHE_BITS
 					  + GRUB_DISK_SECTOR_BITS)),
 		       data, GRUB_DISK_CACHE_SIZE << GRUB_DISK_SECTOR_BITS);
 	  grub_disk_cache_unlock (disk->dev->id, disk->id,
 				  sector + (agglomerate
 					    << GRUB_DISK_CACHE_BITS));
 	}

       if (agglomerate)
 	{
 	  grub_disk_addr_t i;

 	  err = (disk->dev->read) (disk, transform_sector (disk, sector),
 				   agglomerate << (GRUB_DISK_CACHE_BITS
 						   + GRUB_DISK_SECTOR_BITS
 						   - disk->log_sector_size),
 				   buf);
 	  if (err)
 	    return err;

 	  for (i = 0; i < agglomerate; i ++)
 	    grub_disk_cache_store (disk->dev->id, disk->id,
 				   sector + (i << GRUB_DISK_CACHE_BITS),
 				   (char *) buf
 				   + (i << (GRUB_DISK_CACHE_BITS
 					    + GRUB_DISK_SECTOR_BITS)));


 	  if (disk->read_hook)
 	    (disk->read_hook) (sector, 0, agglomerate << (GRUB_DISK_CACHE_BITS + GRUB_DISK_SECTOR_BITS),
 			       disk->read_hook_data);

 	  sector += agglomerate << GRUB_DISK_CACHE_BITS;
 	  size -= agglomerate << (GRUB_DISK_CACHE_BITS + GRUB_DISK_SECTOR_BITS);
 	  buf = (char *) buf
 	    + (agglomerate << (GRUB_DISK_CACHE_BITS + GRUB_DISK_SECTOR_BITS));
 	}

       if (data)
 	{
 	  if (disk->read_hook)
 	    (disk->read_hook) (sector, 0, (GRUB_DISK_CACHE_SIZE << GRUB_DISK_SECTOR_BITS),
 			       disk->read_hook_data);
 	  sector += GRUB_DISK_CACHE_SIZE;
 	  buf = (char *) buf + (GRUB_DISK_CACHE_SIZE << GRUB_DISK_SECTOR_BITS);
 	  size -= (GRUB_DISK_CACHE_SIZE << GRUB_DISK_SECTOR_BITS);
 	}
     }

   /* And now read the last part.  */
   if (size)
     {
       grub_err_t err;
       err = grub_disk_read_small (disk, sector, 0, size, buf);
       if (err)
 	return err;
     }

   return grub_errno;
 }

 grub_uint64_t
 grub_disk_get_size (grub_disk_t disk)
 {
   if (disk->partition)
     return grub_partition_get_len (disk->partition);
   else if (disk->total_sectors != GRUB_DISK_SIZE_UNKNOWN)
     return disk->total_sectors << (disk->log_sector_size - GRUB_DISK_SECTOR_BITS);
   else
     return GRUB_DISK_SIZE_UNKNOWN;
 }
	/*
	* GRUB -- GRand Unified Bootloader
	* Copyright (C) 2002,2003,2004,2006,2007,2008,2009,2010 Free Software Foundation, Inc.
	*
	* GRUB 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 3 of the License, or
	* (at your option) any later version.
	*
	* GRUB 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 GRUB. If not, see <http://www.gnu.org/licenses/>.
	*/

	#include <grub/disk.h>
	#include <grub/err.h>
	#include <grub/mm.h>
	#include <grub/types.h>
	#include <grub/partition.h>
	#include <grub/misc.h>
	#include <grub/time.h>
	#include <grub/file.h>
	#include <grub/i18n.h>

	#define GRUB_CACHE_TIMEOUT 2

	/* The last time the disk was used. */
	static grub_uint64_t grub_last_time = 0;

	struct grub_disk_cache grub_disk_cache_table[GRUB_DISK_CACHE_NUM];

	void (*grub_disk_firmware_fini) (void);
	int grub_disk_firmware_is_tainted;

	#if DISK_CACHE_STATS
	static unsigned long grub_disk_cache_hits;
	static unsigned long grub_disk_cache_misses;

	void
	grub_disk_cache_get_performance (unsigned long hits, unsigned long misses)
	{
	*hits = grub_disk_cache_hits;
	*misses = grub_disk_cache_misses;
	}
	#endif

	grub_err_t (*grub_disk_write_weak) (grub_disk_t disk,
	grub_disk_addr_t sector,
	grub_off_t offset,
	grub_size_t size,
	const void *buf);
	#include "disk_common.c"

	void
	grub_disk_cache_invalidate_all (void)
	{
	unsigned i;

	for (i = 0; i < GRUB_DISK_CACHE_NUM; i++)
	{
	struct grub_disk_cache *cache = grub_disk_cache_table + i;

	if (cache->data && ! cache->lock)
	{
	grub_free (cache->data);
	cache->data = 0;
	}
	}
	}

	static char *
	grub_disk_cache_fetch (unsigned long dev_id, unsigned long disk_id,
	grub_disk_addr_t sector)
	{
	struct grub_disk_cache *cache;
	unsigned cache_index;

	cache_index = grub_disk_cache_get_index (dev_id, disk_id, sector);
	cache = grub_disk_cache_table + cache_index;

	if (cache->dev_id == dev_id && cache->disk_id == disk_id
	&& cache->sector == sector)
	{
	cache->lock = 1;
	#if DISK_CACHE_STATS
	grub_disk_cache_hits++;
	#endif
	return cache->data;
	}

	#if DISK_CACHE_STATS
	grub_disk_cache_misses++;
	#endif

	return 0;
	}

	static void
	grub_disk_cache_unlock (unsigned long dev_id, unsigned long disk_id,
	grub_disk_addr_t sector)
	{
	struct grub_disk_cache *cache;
	unsigned cache_index;

	cache_index = grub_disk_cache_get_index (dev_id, disk_id, sector);
	cache = grub_disk_cache_table + cache_index;

	if (cache->dev_id == dev_id && cache->disk_id == disk_id
	&& cache->sector == sector)
	cache->lock = 0;
	}

	static grub_err_t
	grub_disk_cache_store (unsigned long dev_id, unsigned long disk_id,
	grub_disk_addr_t sector, const char *data)
	{
	unsigned cache_index;
	struct grub_disk_cache *cache;

	cache_index = grub_disk_cache_get_index (dev_id, disk_id, sector);
	cache = grub_disk_cache_table + cache_index;

	cache->lock = 1;
	grub_free (cache->data);
	cache->data = 0;
	cache->lock = 0;

	cache->data = grub_malloc (GRUB_DISK_SECTOR_SIZE << GRUB_DISK_CACHE_BITS);
	if (! cache->data)
	return grub_errno;

	grub_memcpy (cache->data, data,
	GRUB_DISK_SECTOR_SIZE << GRUB_DISK_CACHE_BITS);
	cache->dev_id = dev_id;
	cache->disk_id = disk_id;
	cache->sector = sector;

	return GRUB_ERR_NONE;
	}



	grub_disk_dev_t grub_disk_dev_list;

	void
	grub_disk_dev_register (grub_disk_dev_t dev)
	{
	dev->next = grub_disk_dev_list;
	grub_disk_dev_list = dev;
	}

	void
	grub_disk_dev_unregister (grub_disk_dev_t dev)
	{
	grub_disk_dev_t *p, q;

	for (p = &grub_disk_dev_list, q = *p; q; p = &(q->next), q = q->next)
	if (q == dev)
	{
	*p = q->next;
	break;
	}
	}

	/* Return the location of the first ',', if any, which is not
	escaped by a '\'. */
	static const char *
	find_part_sep (const char *name)
	{
	const char *p = name;
	char c;

	while ((c = *p++) != '\0')
	{
	if (c == '\\' && *p == ',')
	p++;
	else if (c == ',')
	return p - 1;
	}
	return NULL;
	}

	grub_disk_t
	grub_disk_open (const char *name)
	{
	const char *p;
	grub_disk_t disk;
	grub_disk_dev_t dev;
	char raw = (char ) name;
	grub_uint64_t current_time;

	grub_dprintf ("disk", "Opening `%s'...\n", name);

	disk = (grub_disk_t) grub_zalloc (sizeof (*disk));
	if (! disk)
	return 0;
	disk->log_sector_size = GRUB_DISK_SECTOR_BITS;
	/* Default 1MiB of maximum agglomerate. */
	disk->max_agglomerate = 1048576 >> (GRUB_DISK_SECTOR_BITS
	+ GRUB_DISK_CACHE_BITS);

	p = find_part_sep (name);
	if (p)
	{
	grub_size_t len = p - name;

	raw = grub_malloc (len + 1);
	if (! raw)
	goto fail;

	grub_memcpy (raw, name, len);
	raw[len] = '\0';
	disk->name = grub_strdup (raw);
	}
	else
	disk->name = grub_strdup (name);
	if (! disk->name)
	goto fail;

	for (dev = grub_disk_dev_list; dev; dev = dev->next)
	{
	if ((dev->open) (raw, disk) == GRUB_ERR_NONE)
	break;
	else if (grub_errno == GRUB_ERR_UNKNOWN_DEVICE)
	grub_errno = GRUB_ERR_NONE;
	else
	goto fail;
	}

	if (! dev)
	{
	grub_error (GRUB_ERR_UNKNOWN_DEVICE, N_("disk `%s' not found"),
	name);
	goto fail;
	}
	if (disk->log_sector_size > GRUB_DISK_CACHE_BITS + GRUB_DISK_SECTOR_BITS
	\|\| disk->log_sector_size < GRUB_DISK_SECTOR_BITS)
	{
	grub_error (GRUB_ERR_NOT_IMPLEMENTED_YET,
	"sector sizes of %d bytes aren't supported yet",
	(1 << disk->log_sector_size));
	goto fail;
	}

	disk->dev = dev;

	if (p)
	{
	disk->partition = grub_partition_probe (disk, p + 1);
	if (! disk->partition)
	{
	/* TRANSLATORS: It means that the specified partition e.g.
	hd0,msdos1=/dev/sda1 doesn't exist. */
	grub_error (GRUB_ERR_UNKNOWN_DEVICE, N_("no such partition"));
	goto fail;
	}
	}

	/* The cache will be invalidated about 2 seconds after a device was
	closed. */
	current_time = grub_get_time_ms ();

	if (current_time > (grub_last_time
	+ GRUB_CACHE_TIMEOUT * 1000))
	grub_disk_cache_invalidate_all ();

	grub_last_time = current_time;

	fail:

	if (raw && raw != name)
	grub_free (raw);

	if (grub_errno != GRUB_ERR_NONE)
	{
	grub_error_push ();
	grub_dprintf ("disk", "Opening `%s' failed.\n", name);
	grub_error_pop ();

	grub_disk_close (disk);
	return 0;
	}

	return disk;
	}

	void
	grub_disk_close (grub_disk_t disk)
	{
	grub_partition_t part;
	grub_dprintf ("disk", "Closing `%s'.\n", disk->name);

	if (disk->dev && disk->dev->close)
	(disk->dev->close) (disk);

	/* Reset the timer. */
	grub_last_time = grub_get_time_ms ();

	while (disk->partition)
	{
	part = disk->partition->parent;
	grub_free (disk->partition);
	disk->partition = part;
	}
	grub_free ((void *) disk->name);
	grub_free (disk);
	}

	/* Small read (less than cache size and not pass across cache unit boundaries).
	sector is already adjusted and is divisible by cache unit size.
	*/
	static grub_err_t
	grub_disk_read_small_real (grub_disk_t disk, grub_disk_addr_t sector,
	grub_off_t offset, grub_size_t size, void *buf)
	{
	char *data;
	char *tmp_buf;

	/* Fetch the cache. */
	data = grub_disk_cache_fetch (disk->dev->id, disk->id, sector);
	if (data)
	{
	/* Just copy it! */
	grub_memcpy (buf, data + offset, size);
	grub_disk_cache_unlock (disk->dev->id, disk->id, sector);
	return GRUB_ERR_NONE;
	}

	/* Allocate a temporary buffer. */
	tmp_buf = grub_malloc (GRUB_DISK_SECTOR_SIZE << GRUB_DISK_CACHE_BITS);
	if (! tmp_buf)
	return grub_errno;

	/* Otherwise read data from the disk actually. */
	if (disk->total_sectors == GRUB_DISK_SIZE_UNKNOWN
	\|\| sector + GRUB_DISK_CACHE_SIZE
	< (disk->total_sectors << (disk->log_sector_size - GRUB_DISK_SECTOR_BITS)))
	{
	grub_err_t err;
	err = (disk->dev->read) (disk, transform_sector (disk, sector),
	1U << (GRUB_DISK_CACHE_BITS
	+ GRUB_DISK_SECTOR_BITS
	- disk->log_sector_size), tmp_buf);
	if (!err)
	{
	/* Copy it and store it in the disk cache. */
	grub_memcpy (buf, tmp_buf + offset, size);
	grub_disk_cache_store (disk->dev->id, disk->id,
	sector, tmp_buf);
	grub_free (tmp_buf);
	return GRUB_ERR_NONE;
	}
	}

	grub_free (tmp_buf);
	grub_errno = GRUB_ERR_NONE;

	{
	/* Uggh... Failed. Instead, just read necessary data. */
	unsigned num;
	grub_disk_addr_t aligned_sector;

	sector += (offset >> GRUB_DISK_SECTOR_BITS);
	offset &= ((1 << GRUB_DISK_SECTOR_BITS) - 1);
	aligned_sector = (sector & ~((1ULL << (disk->log_sector_size
	- GRUB_DISK_SECTOR_BITS))
	- 1));
	offset += ((sector - aligned_sector) << GRUB_DISK_SECTOR_BITS);
	num = ((size + offset + (1ULL << (disk->log_sector_size))
	- 1) >> (disk->log_sector_size));

	tmp_buf = grub_malloc (num << disk->log_sector_size);
	if (!tmp_buf)
	return grub_errno;

	if ((disk->dev->read) (disk, transform_sector (disk, aligned_sector),
	num, tmp_buf))
	{
	grub_error_push ();
	grub_dprintf ("disk", "%s read failed\n", disk->name);
	grub_error_pop ();
	grub_free (tmp_buf);
	return grub_errno;
	}
	grub_memcpy (buf, tmp_buf + offset, size);
	grub_free (tmp_buf);
	return GRUB_ERR_NONE;
	}
	}

	static grub_err_t
	grub_disk_read_small (grub_disk_t disk, grub_disk_addr_t sector,
	grub_off_t offset, grub_size_t size, void *buf)
	{
	grub_err_t err;

	err = grub_disk_read_small_real (disk, sector, offset, size, buf);
	if (err)
	return err;
	if (disk->read_hook)
	(disk->read_hook) (sector + (offset >> GRUB_DISK_SECTOR_BITS),
	offset & (GRUB_DISK_SECTOR_SIZE - 1),
	size, disk->read_hook_data);
	return GRUB_ERR_NONE;
	}

	/* Read data from the disk. */
	grub_err_t
	grub_disk_read (grub_disk_t disk, grub_disk_addr_t sector,
	grub_off_t offset, grub_size_t size, void *buf)
	{
	/* First of all, check if the region is within the disk. */
	if (grub_disk_adjust_range (disk, &sector, &offset, size) != GRUB_ERR_NONE)
	{
	grub_error_push ();
	grub_dprintf ("disk", "Read out of range: sector 0x%llx (%s).\n",
	(unsigned long long) sector, grub_errmsg);
	grub_error_pop ();
	return grub_errno;
	}

	/* First read until first cache boundary. */
	if (offset \|\| (sector & (GRUB_DISK_CACHE_SIZE - 1)))
	{
	grub_disk_addr_t start_sector;
	grub_size_t pos;
	grub_err_t err;
	grub_size_t len;

	start_sector = sector & ~((grub_disk_addr_t) GRUB_DISK_CACHE_SIZE - 1);
	pos = (sector - start_sector) << GRUB_DISK_SECTOR_BITS;
	len = ((GRUB_DISK_SECTOR_SIZE << GRUB_DISK_CACHE_BITS)
	- pos - offset);
	if (len > size)
	len = size;
	err = grub_disk_read_small (disk, start_sector,
	offset + pos, len, buf);
	if (err)
	return err;
	buf = (char *) buf + len;
	size -= len;
	offset += len;
	sector += (offset >> GRUB_DISK_SECTOR_BITS);
	offset &= ((1 << GRUB_DISK_SECTOR_BITS) - 1);
	}

	/* Until SIZE is zero... */
	while (size >= (GRUB_DISK_CACHE_SIZE << GRUB_DISK_SECTOR_BITS))
	{
	char *data = NULL;
	grub_disk_addr_t agglomerate;
	grub_err_t err;

	/* agglomerate read until we find a first cached entry. */
	for (agglomerate = 0; agglomerate
	< (size >> (GRUB_DISK_SECTOR_BITS + GRUB_DISK_CACHE_BITS))
	&& agglomerate < disk->max_agglomerate;
	agglomerate++)
	{
	data = grub_disk_cache_fetch (disk->dev->id, disk->id,
	sector + (agglomerate
	<< GRUB_DISK_CACHE_BITS));
	if (data)
	break;
	}

	if (data)
	{
	grub_memcpy ((char *) buf
	+ (agglomerate << (GRUB_DISK_CACHE_BITS
	+ GRUB_DISK_SECTOR_BITS)),
	data, GRUB_DISK_CACHE_SIZE << GRUB_DISK_SECTOR_BITS);
	grub_disk_cache_unlock (disk->dev->id, disk->id,
	sector + (agglomerate
	<< GRUB_DISK_CACHE_BITS));
	}

	if (agglomerate)
	{
	grub_disk_addr_t i;

	err = (disk->dev->read) (disk, transform_sector (disk, sector),
	agglomerate << (GRUB_DISK_CACHE_BITS
	+ GRUB_DISK_SECTOR_BITS
	- disk->log_sector_size),
	buf);
	if (err)
	return err;

	for (i = 0; i < agglomerate; i ++)
	grub_disk_cache_store (disk->dev->id, disk->id,
	sector + (i << GRUB_DISK_CACHE_BITS),
	(char *) buf
	+ (i << (GRUB_DISK_CACHE_BITS
	+ GRUB_DISK_SECTOR_BITS)));


	if (disk->read_hook)
	(disk->read_hook) (sector, 0, agglomerate << (GRUB_DISK_CACHE_BITS + GRUB_DISK_SECTOR_BITS),
	disk->read_hook_data);

	sector += agglomerate << GRUB_DISK_CACHE_BITS;
	size -= agglomerate << (GRUB_DISK_CACHE_BITS + GRUB_DISK_SECTOR_BITS);
	buf = (char *) buf
	+ (agglomerate << (GRUB_DISK_CACHE_BITS + GRUB_DISK_SECTOR_BITS));
	}

	if (data)
	{
	if (disk->read_hook)
	(disk->read_hook) (sector, 0, (GRUB_DISK_CACHE_SIZE << GRUB_DISK_SECTOR_BITS),
	disk->read_hook_data);
	sector += GRUB_DISK_CACHE_SIZE;
	buf = (char *) buf + (GRUB_DISK_CACHE_SIZE << GRUB_DISK_SECTOR_BITS);
	size -= (GRUB_DISK_CACHE_SIZE << GRUB_DISK_SECTOR_BITS);
	}
	}

	/* And now read the last part. */
	if (size)
	{
	grub_err_t err;
	err = grub_disk_read_small (disk, sector, 0, size, buf);
	if (err)
	return err;
	}

	return grub_errno;
	}

	grub_uint64_t
	grub_disk_get_size (grub_disk_t disk)
	{
	if (disk->partition)
	return grub_partition_get_len (disk->partition);
	else if (disk->total_sectors != GRUB_DISK_SIZE_UNKNOWN)
	return disk->total_sectors << (disk->log_sector_size - GRUB_DISK_SECTOR_BITS);
	else
	return GRUB_DISK_SIZE_UNKNOWN;
	}