inotify文件监控

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/*************************************************************************
* Copyright (C) Michael Kerrisk, 2018. *
* *
* This program is free software. You may use, modify, and redistribute it *
* under the terms of the GNU 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.gpl-v3 for details. *
*************************************************************************/

/* Listing 19-1 */

/* demo_inotify.c

Demonstrate the use of the inotify API.

Usage: demo_inotify pathname...

The program monitors each of the files specified on the command line for all
possible file events.

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 <linux/inotify.h>
//#include "tlpi_hdr.h"

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

    printf("mask = %0x ", i->mask);
    #if 1
    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 ");
 #endif
    printf(" ");

    if (i->len > 0)
    printf(" name = %s ", i->name);
}

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

int
main(int argc, char *argv[])
{
    int inotifyFd, wd, j;
    char buf[BUF_LEN] __attribute__ ((aligned(8)));
    unsigned int numRead;
    char *p;
    struct inotify_event *event;

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

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

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

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

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

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

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

        for (p = buf; p < buf + numRead; ) {
            event = (struct inotify_event *) p;
            displayInotifyEvent(event);

            p += sizeof(struct inotify_event) + event->len;
        }
    }
   return 0;
}