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
|
/* See LICENSE file for copyright and license details. */
#include "arg.h"
#include "stream.h"
#include "util.h"
#include <fcntl.h>
#include <limits.h>
#include <stdint.h>
#include <string.h>
#include <unistd.h>
static void
usage(void)
{
eprintf("usage: %s start-point (end-point | 'end') file\n", argv0);
}
int
main(int argc, char *argv[])
{
struct stream stream;
size_t frame_size, start = 0, end = 0, ptr, max, n, ptw;
ssize_t r;
char buf[BUFSIZ];
int to_end = 0;
ARGBEGIN {
default:
usage();
} ARGEND;
if (argc != 3)
usage();
if (!strcmp(argv[0], "end")) {
eprintf("refusing to create video with zero frames\n");
} else if (tozu(argv[0], 0, SIZE_MAX, &start)) {
eprintf("the start point must be an integer in [0, %zu]\n", SIZE_MAX);
}
if (!strcmp(argv[1], "end")) {
to_end = 1;
} else if (tozu(argv[1], 0, SIZE_MAX, &end)) {
eprintf("the end point must be an integer in [0, %zu]\n", SIZE_MAX);
}
stream.file = argv[2];
stream.fd = open(stream.file, O_RDONLY);
if (stream.fd < 0)
eprintf("open %s:", stream.file);
einit_stream(&stream);
if (to_end)
end = stream.frames;
else if (end > stream.frames)
eprintf("end point is after end of video\n");
stream.frames = end - start;
fprint_stream_head(stdout, &stream);
fflush(stdout);
if (ferror(stdout))
eprintf("<stdout>:");
if (stream.width > SIZE_MAX / stream.height)
eprintf("%s: video is too large\n", stream.file);
frame_size = stream.width * stream.height;
if (stream.frames > SSIZE_MAX / frame_size)
eprintf("%s: video is too large\n", stream.file);
if (start >= end)
eprintf("%s\n", start > end ?
"start point is after end point" :
"refusing to create video with zero frames");
end *= frame_size;
start *= frame_size;
for (ptr = start; ptr < end;) {
max = end - ptr;
max = sizeof(buf) < max ? sizeof(buf) : max;
r = read(stream.fd, buf + ptr, max);
if (r < 0)
eprintf("read %s:", stream.file);
if (r == 0)
eprintf("%s: file is shorter than expected\n", stream.file);
ptr += n = (size_t)r;
for (ptw = 0; ptw < n; ptw += (size_t)r) {
r = write(STDOUT_FILENO, buf + ptw, n - ptw);
if (r < 0)
eprintf("write <stdout>:");
}
}
close(stream.fd);
return 0;
}
|
