You've already forked linux-apfs-oot
mirror of
https://github.com/linux-apfs/linux-apfs-oot.git
synced 2026-05-01 15:01:20 -07:00
Ernesto A. Fernández
72e6425af6
Copy the code of the APFS module into its own repository, without the rest of the kernel tree. Development will continue upstream, but the intention is to make life easier for potential users. To get the module to build independently, rewrite the Makefile and add a definition for the APFS_SUPER_MAGIC macro. Since the intention is to support a range of kernel versions, use preprocessor checks to handle kernels without statx, without iversion, and without SB_RDONLY. Provide a README file based on the upstream documentation, but with additional build and mount instructions. Add a LICENSE file as well. Signed-off-by: Ernesto A. Fernández <ernesto.mnd.fernandez@gmail.com>
44 lines
1.0 KiB
C
44 lines
1.0 KiB
C
// SPDX-License-Identifier: GPL-2.0
|
|
/*
|
|
* linux/fs/apfs/object.c
|
|
*
|
|
* Checksum routines for an APFS object
|
|
*/
|
|
|
|
#include <linux/fs.h>
|
|
#include "object.h"
|
|
|
|
/*
|
|
* Note that this is not a generic implementation of fletcher64, as it assumes
|
|
* a message length that doesn't overflow sum1 and sum2. This constraint is ok
|
|
* for apfs, though, since the block size is limited to 2^16. For a more
|
|
* generic optimized implementation, see Nakassis (1988).
|
|
*/
|
|
static u64 apfs_fletcher64(void *addr, size_t len)
|
|
{
|
|
__le32 *buff = addr;
|
|
u64 sum1 = 0;
|
|
u64 sum2 = 0;
|
|
u64 c1, c2;
|
|
int i;
|
|
|
|
for (i = 0; i < len/sizeof(u32); i++) {
|
|
sum1 += le32_to_cpu(buff[i]);
|
|
sum2 += sum1;
|
|
}
|
|
|
|
c1 = sum1 + sum2;
|
|
c1 = 0xFFFFFFFF - do_div(c1, 0xFFFFFFFF);
|
|
c2 = sum1 + c1;
|
|
c2 = 0xFFFFFFFF - do_div(c2, 0xFFFFFFFF);
|
|
|
|
return (c2 << 32) | c1;
|
|
}
|
|
|
|
int apfs_obj_verify_csum(struct super_block *sb, struct apfs_obj_phys *obj)
|
|
{
|
|
return (le64_to_cpu(obj->o_cksum) ==
|
|
apfs_fletcher64((char *) obj + APFS_MAX_CKSUM_SIZE,
|
|
sb->s_blocksize - APFS_MAX_CKSUM_SIZE));
|
|
}
|