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1/* uaccess.c: userspace access functions
2 *
3 * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * as published by the Free Software Foundation; either version
9 * 2 of the License, or (at your option) any later version.
10 */
11
12#include <linux/mm.h>
13#include <linux/module.h>
14#include <asm/uaccess.h>
15
16/*****************************************************************************/
17/*
18 * copy a null terminated string from userspace
19 */
20long strncpy_from_user(char *dst, const char __user *src, long count)
21{
22 unsigned long max;
23 char *p, ch;
24 long err = -EFAULT;
25
26 BUG_ON(count < 0);
27
28 p = dst;
29
30#ifndef CONFIG_MMU
31 if ((unsigned long) src < memory_start)
32 goto error;
33#endif
34
35 if ((unsigned long) src >= get_addr_limit())
36 goto error;
37
38 max = get_addr_limit() - (unsigned long) src;
39 if ((unsigned long) count > max) {
40 memset(dst + max, 0, count - max);
41 count = max;
42 }
43
44 err = 0;
45 for (; count > 0; count--, p++, src++) {
46 __get_user_asm(err, ch, src, "ub", "=r");
47 if (err < 0)
48 goto error;
49 if (!ch)
50 break;
51 *p = ch;
52 }
53
54 err = p - dst; /* return length excluding NUL */
55
56 error:
57 if (count > 0)
58 memset(p, 0, count); /* clear remainder of buffer [security] */
59
60 return err;
61
62} /* end strncpy_from_user() */
63
64EXPORT_SYMBOL(strncpy_from_user);
65
66/*****************************************************************************/
67/*
68 * Return the size of a string (including the ending 0)
69 *
70 * Return 0 on exception, a value greater than N if too long
71 */
72long strnlen_user(const char __user *src, long count)
73{
74 const char __user *p;
75 long err = 0;
76 char ch;
77
78 BUG_ON(count < 0);
79
80#ifndef CONFIG_MMU
81 if ((unsigned long) src < memory_start)
82 return 0;
83#endif
84
85 if ((unsigned long) src >= get_addr_limit())
86 return 0;
87
88 for (p = src; count > 0; count--, p++) {
89 __get_user_asm(err, ch, p, "ub", "=r");
90 if (err < 0)
91 return 0;
92 if (!ch)
93 break;
94 }
95
96 return p - src + 1; /* return length including NUL */
97
98} /* end strnlen_user() */
99
100EXPORT_SYMBOL(strnlen_user);
1/* uaccess.c: userspace access functions
2 *
3 * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * as published by the Free Software Foundation; either version
9 * 2 of the License, or (at your option) any later version.
10 */
11
12#include <linux/mm.h>
13#include <linux/module.h>
14#include <asm/uaccess.h>
15
16/*****************************************************************************/
17/*
18 * copy a null terminated string from userspace
19 */
20long strncpy_from_user(char *dst, const char __user *src, long count)
21{
22 unsigned long max;
23 char *p, ch;
24 long err = -EFAULT;
25
26 BUG_ON(count < 0);
27
28 p = dst;
29
30#ifndef CONFIG_MMU
31 if ((unsigned long) src < memory_start)
32 goto error;
33#endif
34
35 if ((unsigned long) src >= get_addr_limit())
36 goto error;
37
38 max = get_addr_limit() - (unsigned long) src;
39 if ((unsigned long) count > max) {
40 memset(dst + max, 0, count - max);
41 count = max;
42 }
43
44 err = 0;
45 for (; count > 0; count--, p++, src++) {
46 __get_user_asm(err, ch, src, "ub", "=r");
47 if (err < 0)
48 goto error;
49 if (!ch)
50 break;
51 *p = ch;
52 }
53
54 err = p - dst; /* return length excluding NUL */
55
56 error:
57 if (count > 0)
58 memset(p, 0, count); /* clear remainder of buffer [security] */
59
60 return err;
61
62} /* end strncpy_from_user() */
63
64EXPORT_SYMBOL(strncpy_from_user);
65
66/*****************************************************************************/
67/*
68 * Return the size of a string (including the ending 0)
69 *
70 * Return 0 on exception, a value greater than N if too long
71 */
72long strnlen_user(const char __user *src, long count)
73{
74 const char __user *p;
75 long err = 0;
76 char ch;
77
78 BUG_ON(count < 0);
79
80#ifndef CONFIG_MMU
81 if ((unsigned long) src < memory_start)
82 return 0;
83#endif
84
85 if ((unsigned long) src >= get_addr_limit())
86 return 0;
87
88 for (p = src; count > 0; count--, p++) {
89 __get_user_asm(err, ch, p, "ub", "=r");
90 if (err < 0)
91 return 0;
92 if (!ch)
93 break;
94 }
95
96 return p - src + 1; /* return length including NUL */
97
98} /* end strnlen_user() */
99
100EXPORT_SYMBOL(strnlen_user);