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 10.1