驅動程式 - Linux Device Driver(LDD) - Fanotify - 監看某個特定資料夾的OPEN事件

參考資訊：
https://stackoverflow.com/questions/20990842/fanotify-monitor-one-specific-folder-not-the-whole-filesystem
https://stackoverflow.com/questions/1835947/how-do-i-program-for-linuxs-new-fanotify-file-system-monitoring-feature

main.c

#include <fcntl.h>
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/fanotify.h>
#include <sys/stat.h>
#include <sys/types.h>

int main(int argc, char **argv)
{
    int fan = -1;
    char buf[4096] = {0};
    char path[255] = {0};
    char fdpath[32] = {0};
    ssize_t buflen = 0, linklen = 0;
    struct fanotify_event_metadata *metadata = NULL;

    fan = fanotify_init(FAN_CLASS_NOTIF, O_RDONLY);
    fanotify_mark(fan, FAN_MARK_ADD, FAN_OPEN | FAN_EVENT_ON_CHILD, AT_FDCWD, "/tmp");

    while (1) {
        buflen = read(fan, buf, sizeof(buf));
        metadata = (struct fanotify_event_metadata*)&buf;

        while (FAN_EVENT_OK(metadata, buflen)) {
            if (metadata->mask & FAN_Q_OVERFLOW) {
                continue;
            }
            sprintf(fdpath, "/proc/self/fd/%d", metadata->fd);
            linklen = readlink(fdpath, path, sizeof(path) - 1);
            path[linklen] = '\0';
            printf("%s opened by process %d.\n", path, (int)metadata->pid);
            close(metadata->fd);
            metadata = FAN_EVENT_NEXT(metadata, buflen);
        }
    }
}

編譯、執行

$ gcc main.c -o test
$ sudo ./test

接著在另一個視窗輸入如下命令

$ touch /tmp/test

結果

/tmp/test opened by process 15410.