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[mirror_ubuntu-bionic-kernel.git] / mm / util.c
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1#include <linux/slab.h>
2#include <linux/string.h>
3#include <linux/module.h>
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4#include <linux/err.h>
5#include <asm/uaccess.h>
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6
7/**
40c07ae8 8 * __kzalloc - allocate memory. The memory is set to zero.
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9 * @size: how many bytes of memory are required.
10 * @flags: the type of memory to allocate.
11 */
40c07ae8 12void *__kzalloc(size_t size, gfp_t flags)
30992c97 13{
871751e2 14 void *ret = ____kmalloc(size, flags);
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15 if (ret)
16 memset(ret, 0, size);
17 return ret;
18}
40c07ae8 19EXPORT_SYMBOL(__kzalloc);
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20
21/*
22 * kstrdup - allocate space for and copy an existing string
23 *
24 * @s: the string to duplicate
25 * @gfp: the GFP mask used in the kmalloc() call when allocating memory
26 */
27char *kstrdup(const char *s, gfp_t gfp)
28{
29 size_t len;
30 char *buf;
31
32 if (!s)
33 return NULL;
34
35 len = strlen(s) + 1;
871751e2 36 buf = ____kmalloc(len, gfp);
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37 if (buf)
38 memcpy(buf, s, len);
39 return buf;
40}
41EXPORT_SYMBOL(kstrdup);
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42
43/*
44 * strndup_user - duplicate an existing string from user space
45 *
46 * @s: The string to duplicate
47 * @n: Maximum number of bytes to copy, including the trailing NUL.
48 */
49char *strndup_user(const char __user *s, long n)
50{
51 char *p;
52 long length;
53
54 length = strnlen_user(s, n);
55
56 if (!length)
57 return ERR_PTR(-EFAULT);
58
59 if (length > n)
60 return ERR_PTR(-EINVAL);
61
62 p = kmalloc(length, GFP_KERNEL);
63
64 if (!p)
65 return ERR_PTR(-ENOMEM);
66
67 if (copy_from_user(p, s, length)) {
68 kfree(p);
69 return ERR_PTR(-EFAULT);
70 }
71
72 p[length - 1] = '\0';
73
74 return p;
75}
76EXPORT_SYMBOL(strndup_user);