5916700c76
Using strlen as a model, add length checking to create strnlen. Signed-off-by: Ken Steele <ken@tilera.com> Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
48 lines
1.4 KiB
C
48 lines
1.4 KiB
C
/*
|
|
* 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>
|
|
#include "string-endian.h"
|
|
|
|
size_t strnlen(const char *s, size_t count)
|
|
{
|
|
/* Get an aligned pointer. */
|
|
const uintptr_t s_int = (uintptr_t) s;
|
|
const uint64_t *p = (const uint64_t *)(s_int & -8);
|
|
size_t bytes_read = sizeof(*p) - (s_int & (sizeof(*p) - 1));
|
|
size_t len;
|
|
uint64_t v, bits;
|
|
|
|
/* Avoid page fault risk by not reading any bytes when count is 0. */
|
|
if (count == 0)
|
|
return 0;
|
|
|
|
/* Read and MASK the first word. */
|
|
v = *p | MASK(s_int);
|
|
|
|
while ((bits = __insn_v1cmpeqi(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) + (CFZ(bits) >> 3) - s;
|
|
return (len < count ? len : count);
|
|
}
|
|
EXPORT_SYMBOL(strnlen);
|