samples/fanotify/fs-monitor.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright 2021, Collabora Ltd.
   4  */
   5
   6 #define _GNU_SOURCE
   7 #include <errno.h>
   8 #include <err.h>
   9 #include <stdlib.h>
  10 #include <stdio.h>
  11 #include <fcntl.h>
  12 #include <sys/fanotify.h>
  13 #include <sys/types.h>
  14 #include <unistd.h>
  15
  16 #ifndef FAN_FS_ERROR
  17 #define FAN_FS_ERROR            0x00008000
  18 #define FAN_EVENT_INFO_TYPE_ERROR       5
  19
  20 struct fanotify_event_info_error {
  21         struct fanotify_event_info_header hdr;
  22         __s32 error;
  23         __u32 error_count;
  24 };
  25 #endif
  26
  27 #ifndef FILEID_INO32_GEN
  28 #define FILEID_INO32_GEN        1
  29 #endif
  30
  31 #ifndef FILEID_INVALID
  32 #define FILEID_INVALID          0xff
  33 #endif
  34
  35 static void print_fh(struct file_handle *fh)
  36 {
  37         int i;
  38         uint32_t *h = (uint32_t *) fh->f_handle;
  39
  40         printf("\tfh: ");
  41         for (i = 0; i < fh->handle_bytes; i++)
  42                 printf("%hhx", fh->f_handle[i]);
  43         printf("\n");
  44
  45         printf("\tdecoded fh: ");
  46         if (fh->handle_type == FILEID_INO32_GEN)
  47                 printf("inode=%u gen=%u\n", h[0], h[1]);
  48         else if (fh->handle_type == FILEID_INVALID && !fh->handle_bytes)
  49                 printf("Type %d (Superblock error)\n", fh->handle_type);
  50         else
  51                 printf("Type %d (Unknown)\n", fh->handle_type);
  52
  53 }
  54
  55 static void handle_notifications(char *buffer, int len)
  56 {
  57         struct fanotify_event_metadata *event =
  58                 (struct fanotify_event_metadata *) buffer;
  59         struct fanotify_event_info_header *info;
  60         struct fanotify_event_info_error *err;
  61         struct fanotify_event_info_fid *fid;
  62         int off;
  63
  64         for (; FAN_EVENT_OK(event, len); event = FAN_EVENT_NEXT(event, len)) {
  65
  66                 if (event->mask != FAN_FS_ERROR) {
  67                         printf("unexpected FAN MARK: %llx\n",
  68                                                         (unsigned long long)event->mask);
  69                         goto next_event;
  70                 }
  71
  72                 if (event->fd != FAN_NOFD) {
  73                         printf("Unexpected fd (!= FAN_NOFD)\n");
  74                         goto next_event;
  75                 }
  76
  77                 printf("FAN_FS_ERROR (len=%d)\n", event->event_len);
  78
  79                 for (off = sizeof(*event) ; off < event->event_len;
  80                      off += info->len) {
  81                         info = (struct fanotify_event_info_header *)
  82                                 ((char *) event + off);
  83
  84                         switch (info->info_type) {
  85                         case FAN_EVENT_INFO_TYPE_ERROR:
  86                                 err = (struct fanotify_event_info_error *) info;
  87
  88                                 printf("\tGeneric Error Record: len=%d\n",
  89                                        err->hdr.len);
  90                                 printf("\terror: %d\n", err->error);
  91                                 printf("\terror_count: %d\n", err->error_count);
  92                                 break;
  93
  94                         case FAN_EVENT_INFO_TYPE_FID:
  95                                 fid = (struct fanotify_event_info_fid *) info;
  96
  97                                 printf("\tfsid: %x%x\n",
  98                                        fid->fsid.val[0], fid->fsid.val[1]);
  99                                 print_fh((struct file_handle *) &fid->handle);
 100                                 break;
 101
 102                         default:
 103                                 printf("\tUnknown info type=%d len=%d:\n",
 104                                        info->info_type, info->len);
 105                         }
 106                 }
 107 next_event:
 108                 printf("---\n\n");
 109         }
 110 }
 111
 112 int main(int argc, char **argv)
 113 {
 114         int fd;
 115
 116         char buffer[BUFSIZ];
 117
 118         if (argc < 2) {
 119                 printf("Missing path argument\n");
 120                 return 1;
 121         }
 122
 123         fd = fanotify_init(FAN_CLASS_NOTIF|FAN_REPORT_FID, O_RDONLY);
 124         if (fd < 0)
 125                 errx(1, "fanotify_init");
 126
 127         if (fanotify_mark(fd, FAN_MARK_ADD|FAN_MARK_FILESYSTEM,
 128                           FAN_FS_ERROR, AT_FDCWD, argv[1])) {
 129                 errx(1, "fanotify_mark");
 130         }
 131
 132         while (1) {
 133                 int n = read(fd, buffer, BUFSIZ);
 134
 135                 if (n < 0)
 136                         errx(1, "read");
 137
 138                 handle_notifications(buffer, n);
 139         }
 140
 141         return 0;
 142 }