amiga.c 4.76 KB
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/* amiga.c - Read amiga partition tables (RDB).  */
/*
 *  GRUB  --  GRand Unified Bootloader
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 *  Copyright (C) 2002,2004,2005,2006,2007  Free Software Foundation, Inc.
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 *
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 *  GRUB is free software: you can redistribute it and/or modify
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 *  it under the terms of the GNU General Public License as published by
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 *  the Free Software Foundation, either version 3 of the License, or
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 *  (at your option) any later version.
 *
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 *  GRUB is distributed in the hope that it will be useful,
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 *  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
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 *  along with GRUB.  If not, see <http://www.gnu.org/licenses/>.
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 */

#include <grub/disk.h>
#include <grub/misc.h>
#include <grub/mm.h>
#include <grub/partition.h>
#include <grub/dl.h>

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GRUB_MOD_LICENSE ("GPLv3+");

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#define AMIGA_CHECKSUM_WORDS 128

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struct grub_amiga_rdsk
{
  /* "RDSK".  */
  grub_uint8_t magic[4];
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#define GRUB_AMIGA_RDSK_MAGIC "RDSK"
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  grub_uint32_t size;
  grub_int32_t checksum;
  grub_uint32_t scsihost;
  grub_uint32_t blksz;
  grub_uint32_t flags;
  grub_uint32_t badblcklst;
  grub_uint32_t partitionlst;
  grub_uint32_t fslst;
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  grub_uint32_t unused[AMIGA_CHECKSUM_WORDS - 9];
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} GRUB_PACKED;
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struct grub_amiga_partition
{
  /* "PART".  */
  grub_uint8_t magic[4];
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#define GRUB_AMIGA_PART_MAGIC "PART"
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  grub_uint32_t size;
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  grub_int32_t checksum;
  grub_uint32_t scsihost;
  grub_uint32_t next;
  grub_uint32_t flags;
  grub_uint32_t unused1[2];
  grub_uint32_t devflags;
  grub_uint8_t namelen;
  grub_uint8_t name[31];
  grub_uint32_t unused2[15];

  grub_uint32_t unused3[3];
  grub_uint32_t heads;
  grub_uint32_t unused4;
  grub_uint32_t block_per_track;
  grub_uint32_t unused5[3];
  grub_uint32_t lowcyl;
  grub_uint32_t highcyl;
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  grub_uint32_t firstcyl;
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  grub_uint32_t unused[AMIGA_CHECKSUM_WORDS - 44];
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} GRUB_PACKED;
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static struct grub_partition_map grub_amiga_partition_map;


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static grub_uint32_t
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amiga_partition_map_checksum (void *buf)
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{
  grub_uint32_t *ptr = buf;
  grub_uint32_t r = 0;
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  grub_size_t sz;
  /* Fancy and quick way of checking sz >= 512 / 4 = 128.  */
  if (ptr[1] & ~grub_cpu_to_be32_compile_time (AMIGA_CHECKSUM_WORDS - 1))
    sz = AMIGA_CHECKSUM_WORDS;
  else
    sz = grub_be_to_cpu32 (ptr[1]);

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  for (; sz; sz--, ptr++)
    r += grub_be_to_cpu32 (*ptr);
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  return r;
}

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static grub_err_t
amiga_partition_map_iterate (grub_disk_t disk,
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			     grub_partition_iterate_hook_t hook,
			     void *hook_data)
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{
  struct grub_partition part;
  struct grub_amiga_rdsk rdsk;
  int partno = 0;
  int next = -1;
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  unsigned pos;
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  /* The RDSK block is one of the first 15 blocks.  */
  for (pos = 0; pos < 15; pos++)
    {
      /* Read the RDSK block which is a descriptor for the entire disk.  */
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      if (grub_disk_read (disk, pos, 0, sizeof (rdsk), &rdsk))
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	return grub_errno;
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      if (grub_memcmp (rdsk.magic, GRUB_AMIGA_RDSK_MAGIC,
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		       sizeof (rdsk.magic)) == 0
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	  && amiga_partition_map_checksum (&rdsk) == 0)
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	{
	  /* Found the first PART block.  */
	  next = grub_be_to_cpu32 (rdsk.partitionlst);
	  break;
	}
    }
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  if (next == -1)
    return grub_error (GRUB_ERR_BAD_PART_TABLE,
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		       "Amiga partition map not found");
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  /* The end of the partition list is marked using "-1".  */
  while (next != -1)
    {
      struct grub_amiga_partition apart;
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      /* Read the RDSK block which is a descriptor for the entire disk.  */
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      if (grub_disk_read (disk, next, 0, sizeof (apart), &apart))
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	return grub_errno;
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      if (grub_memcmp (apart.magic, GRUB_AMIGA_PART_MAGIC,
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		       sizeof (apart.magic)) != 0
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	  || amiga_partition_map_checksum (&apart) != 0)
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	return grub_error (GRUB_ERR_BAD_PART_TABLE,
			   "invalid Amiga partition map");
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      /* Calculate the first block and the size of the partition.  */
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      part.start = (grub_be_to_cpu32 (apart.lowcyl)
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		    * grub_be_to_cpu32 (apart.heads)
		    * grub_be_to_cpu32 (apart.block_per_track));
      part.len = ((grub_be_to_cpu32 (apart.highcyl)
		   - grub_be_to_cpu32 (apart.lowcyl) + 1)
		  * grub_be_to_cpu32 (apart.heads)
		  * grub_be_to_cpu32 (apart.block_per_track));
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      part.offset = next;
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      part.number = partno;
      part.index = 0;
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      part.partmap = &grub_amiga_partition_map;
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      if (hook (disk, &part, hook_data))
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	return grub_errno;
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      next = grub_be_to_cpu32 (apart.next);
      partno++;
    }
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  return 0;
}


/* Partition map type.  */
static struct grub_partition_map grub_amiga_partition_map =
  {
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    .name = "amiga",
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    .iterate = amiga_partition_map_iterate,
  };

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GRUB_MOD_INIT(part_amiga)
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{
  grub_partition_map_register (&grub_amiga_partition_map);
}

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GRUB_MOD_FINI(part_amiga)
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{
  grub_partition_map_unregister (&grub_amiga_partition_map);
}