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);