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
|
/* Copyright (C) 1991, 1992, 1996 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB. If not,
write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA. */
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <sys/uio.h>
/* Read data from file descriptor FD, and put the result in the
buffers described by VECTOR, which is a vector of COUNT `struct iovec's.
The buffers are filled in the order specified.
Operates just like `read' (see <unistd.h>) except that data are
put in VECTOR instead of a contiguous buffer. */
ssize_t
readv (fd, vector, count)
int fd;
const struct iovec *vector;
int count;
{
char *buffer;
size_t bytes;
int bytes_read;
int i;
/* Find the total number of bytes to be read. */
bytes = 0;
for (i = 0; i < count; ++i)
bytes += vector[i].iov_len;
/* Allocate a temporary buffer to hold the data. */
buffer = (char *) __alloca (bytes);
/* Read the data. */
bytes_read = read (fd, buffer, bytes);
if (bytes_read <= 0)
return -1;
/* Copy the data from BUFFER into the memory specified by VECTOR. */
bytes = bytes_read;
for (i = 0; i < count; ++i)
{
#define min(a, b) ((a) > (b) ? (b) : (a))
size_t copy = min (vector[i].iov_len, bytes);
(void) memcpy ((void *) vector[i].iov_base, (void *) buffer, copy);
buffer += copy;
bytes -= copy;
if (bytes == 0)
break;
}
return bytes_read;
}
|
