Watch-and-shutdown.c

/**********************************************************************\
*                Copyright (C) Philip Hannent, 2012.                   *
*                                                                      *
* This program is free software. You may use, modify, and redistribute *
* it under the terms of the GNU Affero General Public License as       *
* published by the Free Software Foundation, either version 3 or (at   *
* your option) any later version. This program is distributed without  *
* any warranty. See the file COPYING for details.                      *
\**********************************************************************/

/* Watch-and_Shutdown.c

   Demonstrate the use of the inotify API.

   Usage: Watch-and_Shutdown pathname

   The program monitors a file for if it is accessed and if that access is greater
   than 5 seconds it will cause a shutdown command to be issued to the operating system

   This program is Linux-specific. The inotify API is available in Linux 2.6.13
   and later.
*/
#include <sys/inotify.h>
#include <limits.h>
#include "tlpi_hdr.h"
#include <stdio.h>
#include <time.h>

/* Process information from inotify_event structure */
static void             
processInotifyEvent(struct inotify_event *i, int *time_set, time_t* )
{
    printf("    wd =%2d; ", i->wd);
    if (i->cookie > 0)
        printf("cookie =%4d; ", i->cookie);

    printf("mask = ");
    if (i->mask & IN_ACCESS)        printf("IN_ACCESS ");
    if (i->mask & IN_ATTRIB)        printf("IN_ATTRIB ");
    if (i->mask & IN_CLOSE_NOWRITE) printf("IN_CLOSE_NOWRITE ");
    if (i->mask & IN_CLOSE_WRITE)   printf("IN_CLOSE_WRITE ");
    if (i->mask & IN_CREATE)        printf("IN_CREATE ");
    if (i->mask & IN_DELETE)        printf("IN_DELETE ");
    if (i->mask & IN_DELETE_SELF)   printf("IN_DELETE_SELF ");
    if (i->mask & IN_IGNORED)       printf("IN_IGNORED ");
    if (i->mask & IN_ISDIR)         printf("IN_ISDIR ");
    if (i->mask & IN_MODIFY)        printf("IN_MODIFY ");
    if (i->mask & IN_MOVE_SELF)     printf("IN_MOVE_SELF ");
    if (i->mask & IN_MOVED_FROM)    printf("IN_MOVED_FROM ");
    if (i->mask & IN_MOVED_TO)      printf("IN_MOVED_TO ");
    if (i->mask & IN_OPEN)          printf("IN_OPEN ");
    if (i->mask & IN_Q_OVERFLOW)    printf("IN_Q_OVERFLOW ");
    if (i->mask & IN_UNMOUNT)       printf("IN_UNMOUNT ");
    printf("\n");

    if (i->len > 0)
        printf("        name = %s\n", i->name);
		
	if (i->mask & IN_ACCESS) {
		printf("        ISSUE SHUTDOWN COMMAND!!!\n");
		/* Perhaps we need to ensure there is access for at least 5 seconds so we know 
			thumbnails are not being created */
		last_time = time(NULL);
		time_set = 1;
	}
}

#define BUF_LEN (10 * (sizeof(struct inotify_event) + NAME_MAX + 1))

int
main(int argc, char *argv[])
{
    int inotifyFd, wd, j, time_set;
    char buf[BUF_LEN];
    ssize_t numRead;
    char *p;
    struct inotify_event *event;
	time_t last_time;

    if (argc < 2 || strcmp(argv[1], "--help") == 0)
        usageErr("%s pathname...\n", argv[0]);

    inotifyFd = inotify_init();                 /* Create inotify instance */
    if (inotifyFd == -1)
        errExit("inotify_init");

    /* For each command-line argument, add a watch for all events */

    for (j = 1; j < argc; j++) {
        wd = inotify_add_watch(inotifyFd, argv[j], IN_ALL_EVENTS);
        if (wd == -1)
            errExit("inotify_add_watch");

        printf("Watching %s using wd %d\n", argv[j], wd);
    }

    for (;;) {                                  /* Read events forever */
        numRead = read(inotifyFd, buf, BUF_LEN);
        if (numRead == 0)
            fatal("read() from inotify fd returned 0!");

        if (numRead == -1)
            errExit("read");

        printf("Read %ld bytes from inotify fd\n", (long) numRead);

        /* Process all of the events in buffer returned by read() */

        for (p = buf; p < buf + numRead; ) {
            event = (struct inotify_event *) p;
            processInotifyEvent(event, time_set, last_time);

            p += sizeof(struct inotify_event) + event->len;
        }
    }

    exit(EXIT_SUCCESS);
}