util.c revision 1d2c8eea698514cfaa53fc991b960791d09508e1 
1#include <linux/slab.h>
2#include <linux/string.h>
3#include <linux/module.h>
4#include <linux/err.h>
5#include <asm/uaccess.h>
6
7/**
8 * __kzalloc - allocate memory. The memory is set to zero.
9 * @size: how many bytes of memory are required.
10 * @flags: the type of memory to allocate.
11 */
12void *__kzalloc(size_t size, gfp_t flags)
13{
14	void *ret = kmalloc_track_caller(size, flags);
15	if (ret)
16		memset(ret, 0, size);
17	return ret;
18}
19EXPORT_SYMBOL(__kzalloc);
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;
36	buf = kmalloc_track_caller(len, gfp);
37	if (buf)
38		memcpy(buf, s, len);
39	return buf;
40}
41EXPORT_SYMBOL(kstrdup);
42
43/**
44 * kmemdup - duplicate region of memory
45 *
46 * @src: memory region to duplicate
47 * @len: memory region length
48 * @gfp: GFP mask to use
49 */
50void *kmemdup(const void *src, size_t len, gfp_t gfp)
51{
52	void *p;
53
54	p = kmalloc_track_caller(len, gfp);
55	if (p)
56		memcpy(p, src, len);
57	return p;
58}
59EXPORT_SYMBOL(kmemdup);
60
61/*
62 * strndup_user - duplicate an existing string from user space
63 *
64 * @s: The string to duplicate
65 * @n: Maximum number of bytes to copy, including the trailing NUL.
66 */
67char *strndup_user(const char __user *s, long n)
68{
69	char *p;
70	long length;
71
72	length = strnlen_user(s, n);
73
74	if (!length)
75		return ERR_PTR(-EFAULT);
76
77	if (length > n)
78		return ERR_PTR(-EINVAL);
79
80	p = kmalloc(length, GFP_KERNEL);
81
82	if (!p)
83		return ERR_PTR(-ENOMEM);
84
85	if (copy_from_user(p, s, length)) {
86		kfree(p);
87		return ERR_PTR(-EFAULT);
88	}
89
90	p[length - 1] = '\0';
91
92	return p;
93}
94EXPORT_SYMBOL(strndup_user);
95