NAME

uio_copyin, uio_copyout — copy data to or from an address space named by a uio_seg_t

SYNOPSIS

#include <sys/uio.h>

int
uio_copyin(const void *src, void *dst, size_t n, uio_seg_t seg);

int
uio_copyout(const void *src, void *dst, size_t n, uio_seg_t seg);

INTERFACE LEVEL

illumos DDI specific

PARAMETERS

src: Source address of the copy.
dst: Destination address of the copy.
n: Number of bytes to copy.
seg: The address space in which the caller's buffer lies, one of UIO_USERSPACE, UIO_USERISPACE or UIO_SYSSPACE.

DESCRIPTION

The uio_copyin() function copies n bytes of data from src, which lies in the address space named by seg, to the kernel address dst. The uio_copyout() function copies in the other direction, from the kernel address src to dst in the address space named by seg.

These functions are for code which can be handed data in either user or kernel memory, with its location described by a uio_seg_t, and which would otherwise have to select between copyin(9F) and kcopy(9F) itself. They are the uio_seg_t counterparts of ddi_copyin(9F) and ddi_copyout(9F), which provide the same service for the mode flags passed to an ioctl(9E) entry point.

When seg is UIO_USERSPACE or UIO_USERISPACE, the caller's buffer lies in the user address space of the calling process and the copy behaves as copyin(9F) or copyout(9F). When seg is UIO_SYSSPACE, both addresses are kernel addresses and the copy is performed with kcopy(9F). In every case a fault taken during the copy is returned to the caller rather than causing the system to panic. Passing any other value as seg causes the system to panic.

CONTEXT

When seg is UIO_USERSPACE or UIO_USERISPACE, these functions can be called from user context only. When seg is UIO_SYSSPACE, they can be called from user or kernel context.

RETURN VALUES

Upon successful completion, the uio_copyin() and uio_copyout() functions return 0. Otherwise, -1 is returned to indicate that a fault occurred and the copy did not complete.