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// SPDX-License-Identifier: GPL-2.0
/*
* fs/f2fs/hash.c
*
* Copyright (c) 2012 Samsung Electronics Co., Ltd.
* http://www.samsung.com/
*
* Portions of this code from linux/fs/ext3/hash.c
*
* Copyright (C) 2002 by Theodore Ts'o
*/
#include <linux/types.h>
#include <linux/fs.h>
#include <linux/f2fs_fs.h>
#include <linux/pagemap.h>
#include <linux/unicode.h>
#include "f2fs.h"
/*
* Hashing code copied from ext3
*/
#define DELTA 0x9E3779B9
static void TEA_transform(unsigned int buf[4], unsigned int const in[])
{
__u32 sum = 0;
__u32 b0 = buf[0], b1 = buf[1];
__u32 a = in[0], b = in[1], c = in[2], d = in[3];
int n = 16;
do {
sum += DELTA;
b0 += ((b1 << 4)+a) ^ (b1+sum) ^ ((b1 >> 5)+b);
b1 += ((b0 << 4)+c) ^ (b0+sum) ^ ((b0 >> 5)+d);
} while (--n);
buf[0] += b0;
buf[1] += b1;
}
static void str2hashbuf(const unsigned char *msg, size_t len,
unsigned int *buf, int num)
{
unsigned pad, val;
int i;
pad = (__u32)len | ((__u32)len << 8);
pad |= pad << 16;
val = pad;
if (len > num * 4)
len = num * 4;
for (i = 0; i < len; i++) {
if ((i % 4) == 0)
val = pad;
val = msg[i] + (val << 8);
if ((i % 4) == 3) {
*buf++ = val;
val = pad;
num--;
}
}
if (--num >= 0)
*buf++ = val;
while (--num >= 0)
*buf++ = pad;
}
static u32 TEA_hash_name(const u8 *p, size_t len)
{
__u32 in[8], buf[4];
/* Initialize the default seed for the hash checksum functions */
buf[0] = 0x67452301;
buf[1] = 0xefcdab89;
buf[2] = 0x98badcfe;
buf[3] = 0x10325476;
while (1) {
str2hashbuf(p, len, in, 4);
TEA_transform(buf, in);
p += 16;
if (len <= 16)
break;
len -= 16;
}
return buf[0] & ~F2FS_HASH_COL_BIT;
}
/*
* Compute @fname->hash. For all directories, @fname->disk_name must be set.
* For casefolded directories, @fname->usr_fname must be set, and also
* @fname->cf_name if the filename is valid Unicode and is not "." or "..".
*/
void f2fs_hash_filename(const struct inode *dir, struct f2fs_filename *fname)
{
const u8 *name = fname->disk_name.name;
size_t len = fname->disk_name.len;
WARN_ON_ONCE(!name);
if (is_dot_dotdot(name, len)) {
fname->hash = 0;
return;
}
#if IS_ENABLED(CONFIG_UNICODE)
if (IS_CASEFOLDED(dir)) {
/*
* If the casefolded name is provided, hash it instead of the
* on-disk name. If the casefolded name is *not* provided, that
* should only be because the name wasn't valid Unicode or was
* "." or "..", so fall back to treating the name as an opaque
* byte sequence. Note that to handle encrypted directories,
* the fallback must use usr_fname (plaintext) rather than
* disk_name (ciphertext).
*/
WARN_ON_ONCE(!fname->usr_fname->name);
if (fname->cf_name.name) {
name = fname->cf_name.name;
len = fname->cf_name.len;
} else {
name = fname->usr_fname->name;
len = fname->usr_fname->len;
}
if (IS_ENCRYPTED(dir)) {
struct qstr tmp = QSTR_INIT(name, len);
fname->hash =
cpu_to_le32(fscrypt_fname_siphash(dir, &tmp));
return;
}
}
#endif
fname->hash = cpu_to_le32(TEA_hash_name(name, len));
}
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