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  1. #define _GNU_SOURCE
  2. #include <errno.h>
  3. #include <fcntl.h>
  4. #include <limits.h>
  5. #include <stdio.h>
  6. #include <stdlib.h>
  7. #include <sys/types.h>
  8. #include <sys/stat.h>
  9. #include <sys/fanotify.h>
  10. #include <unistd.h>
  11.  
  12. #define BUF_SIZE 65536
  13.  
  14. int
  15. main(int argc, char **argv)
  16. {
  17.    int fd, ret, event_fd;
  18.    ssize_t len, path_len;
  19.    char path[PATH_MAX];
  20.    char procfd_path[PATH_MAX];
  21.    char events_buf[BUF_SIZE];
  22.    struct file_handle *file_handle;
  23.    struct fanotify_event_metadata *metadata;
  24.    struct fanotify_event_info_fid *fid;
  25.  
  26.    if (argc != 2) {
  27.        fprintf(stderr, "Invalid number of command line arguments.\n");
  28.        exit(EXIT_FAILURE);
  29.    }
  30.  
  31.    /* Create an fanotify file descriptor with FAN_REPORT_FID as a flag
  32.       so that program can receive fid events. */
  33.  
  34.    fd = fanotify_init(FAN_CLASS_NOTIF | FAN_REPORT_FID, 0);
  35.    if (fd == -1) {
  36.        perror("fanotify_init");
  37.        exit(EXIT_FAILURE);
  38.    }
  39.  
  40.    /* Place a mark on the filesystem object supplied in argv[1]. */
  41.  
  42.    ret = fanotify_mark(fd, FAN_MARK_ADD | FAN_MARK_FILESYSTEM,
  43.                        ( FAN_CREATE | FAN_DELETE | FAN_MODIFY | FAN_MOVE | FAN_ONDIR | FAN_EVENT_ON_CHILD),
  44.                        AT_FDCWD, argv[1]);
  45.    if (ret == -1) {
  46.        perror("fanotify_mark");
  47.        exit(EXIT_FAILURE);
  48.    }
  49.  
  50.    printf("Listening for events.\n");
  51.  
  52.    /* Read events from the event queue into a buffer */
  53.  
  54.    len = read(fd, (void *) &events_buf, sizeof(events_buf));
  55.    if (len == -1 && errno != EAGAIN) {
  56.        perror("read");
  57.        exit(EXIT_FAILURE);
  58.    }
  59.  
  60.    /* Process all events within the buffer */
  61.  
  62.    for (metadata = (struct fanotify_event_metadata *) events_buf;
  63.            FAN_EVENT_OK(metadata, len);
  64.            metadata = FAN_EVENT_NEXT(metadata, len)) {
  65.        fid = (struct fanotify_event_info_fid *) (metadata + 1);
  66.        file_handle = (struct file_handle *) fid->handle;
  67.  
  68.         if (metadata->mask & FAN_CREATE) {
  69.             printf ("\tFAN_CREATE\n");
  70.         }
  71.         if (metadata->mask & FAN_DELETE) {
  72.             printf ("\tFAN_DELETE\n");
  73.         }
  74.         if (metadata->mask & FAN_MODIFY) {
  75.             printf ("\tFAN_MODIFY\n");
  76.         }
  77.         if (metadata->mask & FAN_MOVE) {
  78.             printf ("\tFAN_MOVE\n");
  79.         }
  80.         if (metadata->mask & FAN_ONDIR) {
  81.             printf ("\tFAN_ONDIR\n");
  82.         }
  83.         if (metadata->mask & FAN_EVENT_ON_CHILD) {
  84.             printf ("\tFAN_EVENT_ON_CHILD\n");
  85.         }
  86.  
  87.  
  88.        /* Ensure that the event info is of the correct type */
  89.  
  90.        if (fid->hdr.info_type != FAN_EVENT_INFO_TYPE_FID) {
  91.            fprintf(stderr, "Received unexpected event info type.\n");
  92.         //    exit(EXIT_FAILURE);
  93.        }
  94.         printf("event len %u, FAN_EVENT_METADATA_LEN: %ld\n", metadata->event_len, FAN_EVENT_METADATA_LEN);
  95.         printf("header len %d\n", fid->hdr.len);
  96.         printf("enent metadata %p\n", metadata);
  97.         printf("fid %p\n", fid);
  98.         printf("file handle %p\n", file_handle);
  99.  
  100.     //    if (metadata->mask == FAN_CREATE)
  101.     //        printf("FAN_CREATE (file created):");
  102.  
  103.     //    if (metadata->mask == FAN_CREATE | FAN_ONDIR)
  104.     //        printf("FAN_CREATE | FAN_ONDIR (subdirectory created):");
  105.  
  106.        /* metadata->fd is set to FAN_NOFD when FAN_REPORT_FID is enabled.
  107.           To obtain a file descriptor for the file object corresponding to
  108.           an event you can use the struct file_handle that's provided
  109.           within the fanotify_event_info_fid in conjunction with the
  110.           open_by_handle_at(2) system call. A check for ESTALE is done
  111.           to accommodate for the situation where the file handle for the
  112.           object was deleted prior to this system call. */
  113.  
  114.        event_fd = open_by_handle_at(AT_FDCWD, file_handle, O_RDONLY);
  115.        if (event_fd == -1) {
  116.            if (errno == ESTALE) {
  117.                printf("File handle is no longer valid. "
  118.                        "File has been deleted\n");
  119.                continue;
  120.            } else {
  121.                perror("open_by_handle_at");
  122.                exit(EXIT_FAILURE);
  123.         }
  124.        }
  125.  
  126.        snprintf(procfd_path, sizeof(procfd_path), "/proc/self/fd/%d",
  127.                event_fd);
  128.  
  129.        /* Retrieve and print the path of the modified dentry */
  130.  
  131.        path_len = readlink(procfd_path, path, sizeof(path) - 1);
  132.        if (path_len == -1) {
  133.            perror("readlink");
  134.            exit(EXIT_FAILURE);
  135.        }
  136.  
  137.        path[path_len] = '\0';
  138.        printf("\tDirectory '%s' has been modified.\n", path);
  139.  
  140.        /* Close associated file descriptor for this event */
  141.  
  142.        close(event_fd);
  143.    }
  144.  
  145.    printf("All events processed successfully. Program exiting.\n");
  146.    exit(EXIT_SUCCESS);
  147. }
Compilation error #stdin compilation error #stdout 0s 0KB
comments (?)
stdin 
Standard input is empty
compilation info 
prog.c: In function ‘main’:
prog.c:34:41: error: ‘FAN_REPORT_FID’ undeclared (first use in this function); did you mean ‘FAN_REPORT_TID’?
    fd = fanotify_init(FAN_CLASS_NOTIF | FAN_REPORT_FID, 0);
                                         ^~~~~~~~~~~~~~
                                         FAN_REPORT_TID
prog.c:34:41: note: each undeclared identifier is reported only once for each function it appears in
prog.c:43:26: error: ‘FAN_CREATE’ undeclared (first use in this function); did you mean ‘DN_CREATE’?
                        ( FAN_CREATE | FAN_DELETE | FAN_MODIFY | FAN_MOVE | FAN_ONDIR | FAN_EVENT_ON_CHILD),
                          ^~~~~~~~~~
                          DN_CREATE
prog.c:43:39: error: ‘FAN_DELETE’ undeclared (first use in this function); did you mean ‘DN_DELETE’?
                        ( FAN_CREATE | FAN_DELETE | FAN_MODIFY | FAN_MOVE | FAN_ONDIR | FAN_EVENT_ON_CHILD),
                                       ^~~~~~~~~~
                                       DN_DELETE
prog.c:43:65: error: ‘FAN_MOVE’ undeclared (first use in this function); did you mean ‘FAN_NOFD’?
                        ( FAN_CREATE | FAN_DELETE | FAN_MODIFY | FAN_MOVE | FAN_ONDIR | FAN_EVENT_ON_CHILD),
                                                                 ^~~~~~~~
                                                                 FAN_NOFD
prog.c:66:48: error: dereferencing pointer to incomplete type ‘struct fanotify_event_info_fid’
        file_handle = (struct file_handle *) fid->handle;
                                                ^~
prog.c:90:34: error: ‘FAN_EVENT_INFO_TYPE_FID’ undeclared (first use in this function); did you mean ‘FAN_EVENT_ON_CHILD’?
        if (fid->hdr.info_type != FAN_EVENT_INFO_TYPE_FID) {
                                  ^~~~~~~~~~~~~~~~~~~~~~~
                                  FAN_EVENT_ON_CHILD
stdout 
Standard output is empty
https://ideone.com/isSMfd
language:
C (gcc 8.3)
created:
4 years ago
visibility:
public

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