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csum_partial_copy.c
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1 /*
2  * INET An implementation of the TCP/IP protocol suite for the LINUX
3  * operating system. INET is implemented using the BSD Socket
4  * interface as the means of communication with the user level.
5  *
6  * M32R specific IP/TCP/UDP checksumming routines
7  * (Some code taken from MIPS architecture)
8  *
9  * This file is subject to the terms and conditions of the GNU General Public
10  * License. See the file "COPYING" in the main directory of this archive
11  * for more details.
12  *
13  * Copyright (C) 1994, 1995 Waldorf Electronics GmbH
14  * Copyright (C) 1998, 1999 Ralf Baechle
15  * Copyright (C) 2001-2005 Hiroyuki Kondo, Hirokazu Takata
16  *
17  */
18 
19 #include <linux/module.h>
20 #include <linux/types.h>
21 #include <linux/string.h>
22 
23 #include <net/checksum.h>
24 #include <asm/byteorder.h>
25 #include <asm/uaccess.h>
26 
27 /*
28  * Copy while checksumming, otherwise like csum_partial
29  */
30 __wsum
31 csum_partial_copy_nocheck (const void *src, void *dst, int len, __wsum sum)
32 {
33  sum = csum_partial(src, len, sum);
34  memcpy(dst, src, len);
35 
36  return sum;
37 }
39 
40 /*
41  * Copy from userspace and compute checksum. If we catch an exception
42  * then zero the rest of the buffer.
43  */
44 __wsum
45 csum_partial_copy_from_user (const void __user *src, void *dst,
46  int len, __wsum sum, int *err_ptr)
47 {
48  int missing;
49 
50  missing = copy_from_user(dst, src, len);
51  if (missing) {
52  memset(dst + len - missing, 0, missing);
53  *err_ptr = -EFAULT;
54  }
55 
56  return csum_partial(dst, len-missing, sum);
57 }