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
 20struct 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
 35static 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
 55static 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		}
107next_event:
108		printf("---\n\n");
109	}
110}
111
112int 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}