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
|
/* Test the pread function.
Copyright (C) 2009 Free Software Foundation, Inc.
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program 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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>. */
/* Written by Jim Meyering. */
#include <config.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <fcntl.h>
#define ASSERT(expr) \
do \
{ \
if (!(expr)) \
{ \
fprintf (stderr, "%s:%d: assertion failed\n", __FILE__, __LINE__); \
fflush (stderr); \
abort (); \
} \
} \
while (0)
#define N (sizeof buf - 1)
int
main (void)
{
char const *file = "in";
int fd;
char buf[] = "0123456789";
off_t pos;
ASSERT (file);
fd = open (file, O_CREAT | O_WRONLY, 0600);
ASSERT (0 <= fd);
ASSERT (write (fd, buf, N) == N);
ASSERT (close (fd) == 0);
fd = open (file, O_RDONLY);
ASSERT (0 <= fd);
for (pos = 0; pos < 3; pos++)
{
size_t i;
off_t init_pos = lseek (fd, pos, SEEK_SET);
ASSERT (init_pos == pos);
for (i = 0; i < N; i++)
{
char byte_buf;
ASSERT (pread (fd, &byte_buf, 1, i) == 1);
ASSERT (byte_buf == buf[i]);
ASSERT (lseek (fd, 0, SEEK_CUR) == init_pos);
}
}
ASSERT (close (fd) == 0);
return 0;
}
|
