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