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
|
// SPDX-License-Identifier: GPL-2.0
/*
* Wait until an inotify event on the given cgroup file.
*/
#include <linux/limits.h>
#include <sys/inotify.h>
#include <sys/mman.h>
#include <sys/ptrace.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <errno.h>
#include <fcntl.h>
#include <poll.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
static const char usage[] = "Usage: %s [-v] <cgroup_file>\n";
static char *file;
static int verbose;
static inline void fail_message(char *msg)
{
fprintf(stderr, msg, file);
exit(1);
}
int main(int argc, char *argv[])
{
char *cmd = argv[0];
int c, fd;
struct pollfd fds = { .events = POLLIN, };
while ((c = getopt(argc, argv, "v")) != -1) {
switch (c) {
case 'v':
verbose++;
break;
}
argv++, argc--;
}
if (argc != 2) {
fprintf(stderr, usage, cmd);
return -1;
}
file = argv[1];
fd = open(file, O_RDONLY);
if (fd < 0)
fail_message("Cgroup file %s not found!\n");
close(fd);
fd = inotify_init();
if (fd < 0)
fail_message("inotify_init() fails on %s!\n");
if (inotify_add_watch(fd, file, IN_MODIFY) < 0)
fail_message("inotify_add_watch() fails on %s!\n");
fds.fd = fd;
/*
* poll waiting loop
*/
for (;;) {
int ret = poll(&fds, 1, 10000);
if (ret < 0) {
if (errno == EINTR)
continue;
perror("poll");
exit(1);
}
if ((ret > 0) && (fds.revents & POLLIN))
break;
}
if (verbose) {
struct inotify_event events[10];
long len;
usleep(1000);
len = read(fd, events, sizeof(events));
printf("Number of events read = %ld\n",
len/sizeof(struct inotify_event));
}
close(fd);
return 0;
}
|
