NULLOP(9)

NULLOP(9) | Kernel Developer's Manual | NULLOP(9)

# 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);

July 25, 2010 | NetBSD 8.3