1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
| | // SPDX-License-Identifier: GPL-2.0-or-later
/*
* iov.h - helpers for using (partial) iovecs.
*
* Copyright Red Hat
* Author: Laurent Vivier <lvivier@redhat.com>
*
* This file also contains code originally from QEMU include/qemu/iov.h
* and licensed under the following terms:
*
* Copyright (C) 2010 Red Hat, Inc.
*
* Author(s):
* Amit Shah <amit.shah@redhat.com>
* Michael Tokarev <mjt@tls.msk.ru>
*
* This work is licensed under the terms of the GNU GPL, version 2. See
* the COPYING file in the top-level directory.
*
* Contributions after 2012-01-13 are licensed under the terms of the
* GNU GPL, version 2 or (at your option) any later version.
*/
#include <sys/socket.h>
#include "util.h"
#include "iov.h"
/* iov_skip_bytes() - Skip leading bytes of an IO vector
* @iov: IO vector
* @n: Number of entries in @iov
* @skip: Number of leading bytes of @iov to skip
* @offset: Offset of first unskipped byte in its @iov entry
*
* Return: index I of individual struct iovec which contains the byte at @skip
* bytes into the vector (as though all its buffers were contiguous).
* If @offset is non-NULL, update it to the offset of that byte within
* @iov[I] (guaranteed to be less than @iov[I].iov_len) If the whole
* vector has <= @skip bytes, return @n.
*/
size_t iov_skip_bytes(const struct iovec *iov, size_t n,
size_t skip, size_t *offset)
{
size_t off = skip, i;
for (i = 0; i < n; i++) {
if (off < iov[i].iov_len)
break;
off -= iov[i].iov_len;
}
if (offset)
*offset = off;
return i;
}
/**
* iov_from_buf - Copy data from a buffer to an I/O vector (struct iovec)
* efficiently.
*
* @iov: Pointer to the array of struct iovec describing the
* scatter/gather I/O vector.
* @iov_cnt: Number of elements in the iov array.
* @offset: Byte offset in the iov array where copying should start.
* @buf: Pointer to the source buffer containing the data to copy.
* @bytes: Total number of bytes to copy from buf to iov.
*
* Returns: The number of bytes successfully copied.
*/
/* cppcheck-suppress unusedFunction */
size_t iov_from_buf(const struct iovec *iov, size_t iov_cnt,
size_t offset, const void *buf, size_t bytes)
{
unsigned int i;
size_t copied;
if (__builtin_constant_p(bytes) && iov_cnt &&
offset <= iov[0].iov_len && bytes <= iov[0].iov_len - offset) {
memcpy((char *)iov[0].iov_base + offset, buf, bytes);
return bytes;
}
i = iov_skip_bytes(iov, iov_cnt, offset, &offset);
/* copying data */
for (copied = 0; copied < bytes && i < iov_cnt; i++) {
size_t len = MIN(iov[i].iov_len - offset, bytes - copied);
memcpy((char *)iov[i].iov_base + offset, (char *)buf + copied,
len);
copied += len;
offset = 0;
}
return copied;
}
/**
* iov_to_buf - Copy data from a scatter/gather I/O vector (struct iovec) to
* a buffer efficiently.
*
* @iov: Pointer to the array of struct iovec describing the scatter/gather
* I/O vector.
* @iov_cnt: Number of elements in the iov array.
* @offset: Offset within the first element of iov from where copying should start.
* @buf: Pointer to the destination buffer where data will be copied.
* @bytes: Total number of bytes to copy from iov to buf.
*
* Returns: The number of bytes successfully copied.
*/
/* cppcheck-suppress unusedFunction */
size_t iov_to_buf(const struct iovec *iov, size_t iov_cnt,
size_t offset, void *buf, size_t bytes)
{
unsigned int i;
size_t copied;
if (__builtin_constant_p(bytes) && iov_cnt &&
offset <= iov[0].iov_len && bytes <= iov[0].iov_len - offset) {
memcpy(buf, (char *)iov[0].iov_base + offset, bytes);
return bytes;
}
i = iov_skip_bytes(iov, iov_cnt, offset, &offset);
/* copying data */
for (copied = 0; copied < bytes && i < iov_cnt; i++) {
size_t len = MIN(iov[i].iov_len - offset, bytes - copied);
memcpy((char *)buf + copied, (char *)iov[i].iov_base + offset,
len);
copied += len;
offset = 0;
}
return copied;
}
/**
* iov_size - Calculate the total size of a scatter/gather I/O vector
* (struct iovec).
*
* @iov: Pointer to the array of struct iovec describing the
* scatter/gather I/O vector.
* @iov_cnt: Number of elements in the iov array.
*
* Returns: The total size in bytes.
*/
size_t iov_size(const struct iovec *iov, size_t iov_cnt)
{
unsigned int i;
size_t len;
for (i = 0, len = 0; i < iov_cnt; i++)
len += iov[i].iov_len;
return len;
}
|