blob: 1434141d9e0148b223b1a6b5311afdf3296af7e8 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
|
/*
* Copyright 2013 Tilera Corporation. All Rights Reserved.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation, version 2.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
* NON INFRINGEMENT. See the GNU General Public License for
* more details.
*/
#include <linux/types.h>
#include <linux/string.h>
#include <linux/module.h>
size_t strnlen(const char *s, size_t count)
{
/* Get an aligned pointer. */
const uintptr_t s_int = (uintptr_t) s;
const uint32_t *p = (const uint32_t *)(s_int & -4);
size_t bytes_read = sizeof(*p) - (s_int & (sizeof(*p) - 1));
size_t len;
uint32_t v, bits;
/* Avoid page fault risk by not reading any bytes when count is 0. */
if (count == 0)
return 0;
/* Read first word, but force bytes before the string to be nonzero. */
v = *p | ((1 << ((s_int << 3) & 31)) - 1);
while ((bits = __insn_seqb(v, 0)) == 0) {
if (bytes_read >= count) {
/* Read COUNT bytes and didn't find the terminator. */
return count;
}
v = *++p;
bytes_read += sizeof(v);
}
len = ((const char *) p) + (__insn_ctz(bits) >> 3) - s;
return (len < count ? len : count);
}
EXPORT_SYMBOL(strnlen);
|
