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libbtrfsutil: add accessors for search header items 

Add helpers that do proper unaligned access of search heade items. This
is done in the non-libbtrfsutil code already, use the same helpers here
too. We can't use the get_unaligned_* helpers that are defined in
kerncompat, so use plain memcpy that will work everywhere.

Signed-off-by: David Sterba <dsterba@suse.com>
master
David Sterba 2019-07-04 14:26:47 +02:00
parent dc6da57e0a
commit db1246039d
1 changed files with 40 additions and 0 deletions
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40
libbtrfsutil/btrfsutil_internal.h
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@ -21,6 +21,7 @@
#define BTRFS_UTIL_INTERNAL_H
#include <asm/byteorder.h>
#include <string.h>
#include "btrfsutil.h"
#include "btrfs.h"
@ -39,4 +40,43 @@
errno = saved_errno; \
} while (0)
/*
* Accessors of search header that is commonly mapped to a byte buffer so the
* alignment is not guraranteed
*/
static inline __u64 btrfs_search_header_transid(const struct btrfs_ioctl_search_header *sh)
{
__u64 tmp;
memcpy(&tmp, &sh->transid, sizeof(__u64));
return tmp;
}
static inline __u64 btrfs_search_header_objectid(const struct btrfs_ioctl_search_header *sh)
{
__u64 tmp;
memcpy(&tmp, &sh->objectid, sizeof(__u64));
return tmp;
}
static inline __u64 btrfs_search_header_offset(const struct btrfs_ioctl_search_header *sh)
{
__u64 tmp;
memcpy(&tmp, &sh->offset, sizeof(__u64));
return tmp;
}
static inline __u32 btrfs_search_header_type(const struct btrfs_ioctl_search_header *sh)
{
__u32 tmp;
memcpy(&tmp, &sh->type, sizeof(__u32));
return tmp;
}
static inline __u32 btrfs_search_header_len(const struct btrfs_ioctl_search_header *sh)
{
__u32 tmp;
memcpy(&tmp, &sh->len, sizeof(__u32));
return tmp;
}
#endif /* BTRFS_UTIL_INTERNAL_H */