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
| /*
| * make-sparse.c --- make a sparse file from stdin
| *
| * Copyright 2004 by Theodore Ts'o.
| *
| * %Begin-Header%
| * This file may be redistributed under the terms of the GNU Public
| * License.
| * %End-Header%
| */
|
| #ifndef _LARGEFILE_SOURCE
| #define _LARGEFILE_SOURCE
| #endif
| #ifndef _LARGEFILE64_SOURCE
| #define _LARGEFILE64_SOURCE
| #endif
|
| #include <stdio.h>
| #include <unistd.h>
| #include <stdlib.h>
| #include <sys/types.h>
| #include <sys/stat.h>
| #include <fcntl.h>
| #include <errno.h>
|
| int full_read(int fd, char *buf, size_t count)
| {
| int got, total = 0;
| int pass = 0;
|
| while (count > 0) {
| got = read(fd, buf, count);
| if (got == -1) {
| if ((errno == EINTR) || (errno == EAGAIN))
| continue;
| return total ? total : -1;
| }
| if (got == 0) {
| if (pass++ >= 3)
| return total;
| continue;
| }
| pass = 0;
| buf += got;
| total += got;
| count -= got;
| }
| return total;
| }
|
| int main(int argc, char **argv)
| {
| int fd, got, i;
| int zflag = 0;
| char buf[1024];
|
| if (argc != 2) {
| fprintf(stderr, "Usage: make-sparse out-file\n");
| exit(1);
| }
| fd = open(argv[1], O_WRONLY|O_CREAT|O_TRUNC|O_LARGEFILE, 0777);
| if (fd < 0) {
| perror(argv[1]);
| exit(1);
| }
| while (1) {
| got = full_read(0, buf, sizeof(buf));
| if (got == 0)
| break;
| if (got == sizeof(buf)) {
| for (i=0; i < sizeof(buf); i++)
| if (buf[i])
| break;
| if (i == sizeof(buf)) {
| lseek(fd, sizeof(buf), SEEK_CUR);
| zflag = 1;
| continue;
| }
| }
| zflag = 0;
| write(fd, buf, got);
| }
| if (zflag) {
| lseek(fd, -1, SEEK_CUR);
| buf[0] = 0;
| write(fd, buf, 1);
| }
| return 0;
| }
|
|
|
