NAME
nullop —
dummy functions
SYNOPSIS
#include <sys/systm.h>
int
nullop(
void
*v);
void
voidop(
void);
int
enodev(
void);
int
enxio(
void);
int
enoioctl(
void);
int
enosys(
void);
int
eopnotsupp(
void);
DESCRIPTION
The
nullop() function provides a generic “null
operation”. It always returns the value 0. The
voidop() function takes no arguments and does nothing.
The
enodev(),
enxio(),
enoioctl(),
enosys(), and
eopnotsupp() functions always fail, returning
ENODEV
,
ENXIO
,
ENOTTY
,
ENOSYS
, and
EOPNOTSUPP
, respectively.
EXAMPLES
The following example demonstrates a case where
nullop() may
be useful:
uint64_t xc;
...
xc = xc_broadcast(0, (xcfunc_t)nullop, NULL, NULL);
xc_wait(xc);