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/*
* Copyright (C) 2018 Harry Mallon <hjmallon@gmail.com>
*
* This file may be redistributed under the terms of the
* GNU Lesser General Public License.
*/
#include "superblocks.h"
#define APFS_CONTAINER_SUPERBLOCK_TYPE 1
#define APFS_CONTAINER_SUPERBLOCK_SUBTYPE 0
#define APFS_STANDARD_BLOCK_SIZE 4096
/*
* This struct is much longer than this, but this seems
* to contain the useful bits (for now).
*
* All values are little-endian.
*/
struct apfs_super_block {
// Generic part to all APFS objects
uint64_t checksum;
uint64_t oid;
uint64_t xid;
uint16_t type;
uint16_t flags;
uint16_t subtype;
uint16_t pad;
// Specific to container header
uint32_t magic; // 'NXSB'
uint32_t block_size;
uint64_t block_count;
uint64_t features;
uint64_t read_only_features;
uint64_t incompatible_features;
uint8_t uuid[16];
};
static int probe_apfs(blkid_probe pr, const struct blkid_idmag *mag)
{
const struct apfs_super_block *sb;
sb = blkid_probe_get_sb(pr, mag, struct apfs_super_block);
if (!sb)
return errno ? -errno : BLKID_PROBE_NONE;
if (le16_to_cpu(sb->type) != APFS_CONTAINER_SUPERBLOCK_TYPE)
return BLKID_PROBE_NONE;
if (le16_to_cpu(sb->subtype) != APFS_CONTAINER_SUPERBLOCK_SUBTYPE)
return BLKID_PROBE_NONE;
if (le16_to_cpu(sb->pad) != 0)
return BLKID_PROBE_NONE;
/*
* This check is pretty draconian, but should avoid false
* positives. Can be improved as more APFS documentation
* is published.
*/
if (le32_to_cpu(sb->block_size) != APFS_STANDARD_BLOCK_SIZE)
return BLKID_PROBE_NONE;
if (blkid_probe_set_uuid(pr, sb->uuid) < 0)
return BLKID_PROBE_NONE;
blkid_probe_set_fsblocksize(pr, le32_to_cpu(sb->block_size));
blkid_probe_set_block_size(pr, le32_to_cpu(sb->block_size));
return BLKID_PROBE_OK;
}
const struct blkid_idinfo apfs_idinfo =
{
.name = "apfs",
.usage = BLKID_USAGE_FILESYSTEM,
.probefunc = probe_apfs,
.magics =
{
{ .magic = "NXSB", .len = 4, .sboff = 32 },
{ NULL }
}
};
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