fanotify: send events using read
Send events to userspace by reading the file descriptor from fanotify_init().
One will get blocks of data which look like:
struct fanotify_event_metadata {
__u32 event_len;
__u32 vers;
__s32 fd;
__u64 mask;
__s64 pid;
__u64 cookie;
} __attribute__ ((packed));
Simple code to retrieve and deal with events is below
while ((len = read(fan_fd, buf, sizeof(buf))) > 0) {
struct fanotify_event_metadata *metadata;
metadata = (void *)buf;
while(FAN_EVENT_OK(metadata, len)) {
[PROCESS HERE!!]
if (metadata->fd >= 0 && close(metadata->fd) != 0)
goto fail;
metadata = FAN_EVENT_NEXT(metadata, len);
}
}
Signed-off-by: Eric Paris <eparis@redhat.com>
diff --git a/include/linux/fanotify.h b/include/linux/fanotify.h
index 95aeea2..c1c6616 100644
--- a/include/linux/fanotify.h
+++ b/include/linux/fanotify.h
@@ -51,6 +51,30 @@
*/
#define FAN_ALL_INCOMING_EVENTS (FAN_ALL_EVENTS |\
FAN_EVENT_ON_CHILD)
+
+#define FAN_ALL_OUTGOING_EVENTS (FAN_ALL_EVENTS |\
+ FAN_Q_OVERFLOW)
+
+#define FANOTIFY_METADATA_VERSION 1
+
+struct fanotify_event_metadata {
+ __u32 event_len;
+ __u32 vers;
+ __s32 fd;
+ __u64 mask;
+} __attribute__ ((packed));
+
+/* Helper functions to deal with fanotify_event_metadata buffers */
+#define FAN_EVENT_METADATA_LEN (sizeof(struct fanotify_event_metadata))
+
+#define FAN_EVENT_NEXT(meta, len) ((len) -= (meta)->event_len, \
+ (struct fanotify_event_metadata*)(((char *)(meta)) + \
+ (meta)->event_len))
+
+#define FAN_EVENT_OK(meta, len) ((long)(len) >= (long)FAN_EVENT_METADATA_LEN && \
+ (long)(meta)->event_len >= (long)FAN_EVENT_METADATA_LEN && \
+ (long)(meta)->event_len <= (long)(len))
+
#ifdef __KERNEL__
#endif /* __KERNEL__ */