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Source at commit fbf123cd4cc0c097fe9a99c90109ebb2a5e94a50 created 10 years 3 months ago. By Lars-Peter Clausen, dma: jz4740: Dequeue descriptor from active list before completing it | |
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1 | #include <linux/module.h> |
2 | #include <linux/uaccess.h> |
3 | #include <linux/kernel.h> |
4 | #include <linux/errno.h> |
5 | |
6 | #include <asm/byteorder.h> |
7 | #include <asm/word-at-a-time.h> |
8 | |
9 | #ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS |
10 | #define IS_UNALIGNED(src, dst) 0 |
11 | #else |
12 | #define IS_UNALIGNED(src, dst) \ |
13 | (((long) dst | (long) src) & (sizeof(long) - 1)) |
14 | #endif |
15 | |
16 | /* |
17 | * Do a strncpy, return length of string without final '\0'. |
18 | * 'count' is the user-supplied count (return 'count' if we |
19 | * hit it), 'max' is the address space maximum (and we return |
20 | * -EFAULT if we hit it). |
21 | */ |
22 | static inline long do_strncpy_from_user(char *dst, const char __user *src, long count, unsigned long max) |
23 | { |
24 | const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; |
25 | long res = 0; |
26 | |
27 | /* |
28 | * Truncate 'max' to the user-specified limit, so that |
29 | * we only have one limit we need to check in the loop |
30 | */ |
31 | if (max > count) |
32 | max = count; |
33 | |
34 | if (IS_UNALIGNED(src, dst)) |
35 | goto byte_at_a_time; |
36 | |
37 | while (max >= sizeof(unsigned long)) { |
38 | unsigned long c, data; |
39 | |
40 | /* Fall back to byte-at-a-time if we get a page fault */ |
41 | if (unlikely(__get_user(c,(unsigned long __user *)(src+res)))) |
42 | break; |
43 | *(unsigned long *)(dst+res) = c; |
44 | if (has_zero(c, &data, &constants)) { |
45 | data = prep_zero_mask(c, data, &constants); |
46 | data = create_zero_mask(data); |
47 | return res + find_zero(data); |
48 | } |
49 | res += sizeof(unsigned long); |
50 | max -= sizeof(unsigned long); |
51 | } |
52 | |
53 | byte_at_a_time: |
54 | while (max) { |
55 | char c; |
56 | |
57 | if (unlikely(__get_user(c,src+res))) |
58 | return -EFAULT; |
59 | dst[res] = c; |
60 | if (!c) |
61 | return res; |
62 | res++; |
63 | max--; |
64 | } |
65 | |
66 | /* |
67 | * Uhhuh. We hit 'max'. But was that the user-specified maximum |
68 | * too? If so, that's ok - we got as much as the user asked for. |
69 | */ |
70 | if (res >= count) |
71 | return res; |
72 | |
73 | /* |
74 | * Nope: we hit the address space limit, and we still had more |
75 | * characters the caller would have wanted. That's an EFAULT. |
76 | */ |
77 | return -EFAULT; |
78 | } |
79 | |
80 | /** |
81 | * strncpy_from_user: - Copy a NUL terminated string from userspace. |
82 | * @dst: Destination address, in kernel space. This buffer must be at |
83 | * least @count bytes long. |
84 | * @src: Source address, in user space. |
85 | * @count: Maximum number of bytes to copy, including the trailing NUL. |
86 | * |
87 | * Copies a NUL-terminated string from userspace to kernel space. |
88 | * |
89 | * On success, returns the length of the string (not including the trailing |
90 | * NUL). |
91 | * |
92 | * If access to userspace fails, returns -EFAULT (some data may have been |
93 | * copied). |
94 | * |
95 | * If @count is smaller than the length of the string, copies @count bytes |
96 | * and returns @count. |
97 | */ |
98 | long strncpy_from_user(char *dst, const char __user *src, long count) |
99 | { |
100 | unsigned long max_addr, src_addr; |
101 | |
102 | if (unlikely(count <= 0)) |
103 | return 0; |
104 | |
105 | max_addr = user_addr_max(); |
106 | src_addr = (unsigned long)src; |
107 | if (likely(src_addr < max_addr)) { |
108 | unsigned long max = max_addr - src_addr; |
109 | return do_strncpy_from_user(dst, src, count, max); |
110 | } |
111 | return -EFAULT; |
112 | } |
113 | EXPORT_SYMBOL(strncpy_from_user); |
114 |
Branches:
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ben-wpan-stefan
javiroman/ks7010
jz-2.6.34
jz-2.6.34-rc5
jz-2.6.34-rc6
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jz-3.9-rc8
jz47xx
jz47xx-2.6.38
master
Tags:
od-2011-09-04
od-2011-09-18
v2.6.34-rc5
v2.6.34-rc6
v2.6.34-rc7
v3.9