timerfd_create() can fail with the following errors:
EINVAL The clockid is not valid.
EINVAL flags is invalid; or, in Linux 2.6.26 or earlier, flags is
nonzero.
EMFILE The per-process limit on the number of open file
descriptors has been reached.
ENFILE The system-wide limit on the total number of open files
has been reached.
ENODEV Could not mount (internal) anonymous inode device.
ENOMEM There was insufficient kernel memory to create the timer.
EPERM clockid was CLOCK_REALTIME_ALARM or CLOCK_BOOTTIME_ALARM
but the caller did not have the CAP_WAKE_ALARM capability.
timerfd_settime() and timerfd_gettime() can fail with the
following errors:
EBADF fd is not a valid file descriptor.
EFAULT new_value, old_value, or curr_value is not valid a
pointer.
EINVAL fd is not a valid timerfd file descriptor.
timerfd_settime() can also fail with the following errors:
ECANCELED
See NOTES.
EINVAL new_value is not properly initialized (one of the tv_nsec
falls outside the range zero to 999,999,999).
EINVAL flags is invalid.
