In addition to the usual errors for read(2), the following errors
can occur when reading from the fanotify file descriptor:
EINVAL The buffer is too small to hold the event.
EMFILE The per-process limit on the number of open files has been
reached. See the description of RLIMIT_NOFILE in
getrlimit(2).
ENFILE The system-wide limit on the total number of open files
has been reached. See /proc/sys/fs/file-max in proc(5).
ETXTBSY
This error is returned by read(2) if O_RDWR or O_WRONLY
was specified in the event_f_flags argument when calling
fanotify_init(2) and an event occurred for a monitored
file that is currently being executed.
In addition to the usual errors for write(2), the following
errors can occur when writing to the fanotify file descriptor:
EINVAL Fanotify access permissions are not enabled in the kernel
configuration or the value of response in the response
structure is not valid.
ENOENT The file descriptor fd in the response structure is not
valid. This may occur when a response for the permission
event has already been written.
