111 lines
2.1 KiB
C
111 lines
2.1 KiB
C
/*
|
|
* cgroup_event_listener.c - Simple listener of cgroup events
|
|
*
|
|
* Copyright (C) Kirill A. Shutemov <kirill@shutemov.name>
|
|
*/
|
|
|
|
#include <assert.h>
|
|
#include <errno.h>
|
|
#include <fcntl.h>
|
|
#include <libgen.h>
|
|
#include <limits.h>
|
|
#include <stdio.h>
|
|
#include <string.h>
|
|
#include <unistd.h>
|
|
|
|
#include <sys/eventfd.h>
|
|
|
|
#define USAGE_STR "Usage: cgroup_event_listener <path-to-control-file> <args>\n"
|
|
|
|
int main(int argc, char **argv)
|
|
{
|
|
int efd = -1;
|
|
int cfd = -1;
|
|
int event_control = -1;
|
|
char event_control_path[PATH_MAX];
|
|
char line[LINE_MAX];
|
|
int ret;
|
|
|
|
if (argc != 3) {
|
|
fputs(USAGE_STR, stderr);
|
|
return 1;
|
|
}
|
|
|
|
cfd = open(argv[1], O_RDONLY);
|
|
if (cfd == -1) {
|
|
fprintf(stderr, "Cannot open %s: %s\n", argv[1],
|
|
strerror(errno));
|
|
goto out;
|
|
}
|
|
|
|
ret = snprintf(event_control_path, PATH_MAX, "%s/cgroup.event_control",
|
|
dirname(argv[1]));
|
|
if (ret >= PATH_MAX) {
|
|
fputs("Path to cgroup.event_control is too long\n", stderr);
|
|
goto out;
|
|
}
|
|
|
|
event_control = open(event_control_path, O_WRONLY);
|
|
if (event_control == -1) {
|
|
fprintf(stderr, "Cannot open %s: %s\n", event_control_path,
|
|
strerror(errno));
|
|
goto out;
|
|
}
|
|
|
|
efd = eventfd(0, 0);
|
|
if (efd == -1) {
|
|
perror("eventfd() failed");
|
|
goto out;
|
|
}
|
|
|
|
ret = snprintf(line, LINE_MAX, "%d %d %s", efd, cfd, argv[2]);
|
|
if (ret >= LINE_MAX) {
|
|
fputs("Arguments string is too long\n", stderr);
|
|
goto out;
|
|
}
|
|
|
|
ret = write(event_control, line, strlen(line) + 1);
|
|
if (ret == -1) {
|
|
perror("Cannot write to cgroup.event_control");
|
|
goto out;
|
|
}
|
|
|
|
while (1) {
|
|
uint64_t result;
|
|
|
|
ret = read(efd, &result, sizeof(result));
|
|
if (ret == -1) {
|
|
if (errno == EINTR)
|
|
continue;
|
|
perror("Cannot read from eventfd");
|
|
break;
|
|
}
|
|
assert(ret == sizeof(result));
|
|
|
|
ret = access(event_control_path, W_OK);
|
|
if ((ret == -1) && (errno == ENOENT)) {
|
|
puts("The cgroup seems to have removed.");
|
|
ret = 0;
|
|
break;
|
|
}
|
|
|
|
if (ret == -1) {
|
|
perror("cgroup.event_control "
|
|
"is not accessible any more");
|
|
break;
|
|
}
|
|
|
|
printf("%s %s: crossed\n", argv[1], argv[2]);
|
|
}
|
|
|
|
out:
|
|
if (efd >= 0)
|
|
close(efd);
|
|
if (event_control >= 0)
|
|
close(event_control);
|
|
if (cfd >= 0)
|
|
close(cfd);
|
|
|
|
return (ret != 0);
|
|
}
|