UIOMOVE(9) BSD Kernel Manual UIOMOVE(9)NAME
uiomove - move data described by a struct uioSYNOPSIS
#include <sys/systm.h>
int
uiomove(void *buf, int n, struct uio *uio);
DESCRIPTION
The uiomove function copies up to n bytes between the kernel-space ad-
dress pointed to by buf and the addresses described by uio, which may be
in user-space or kernel-space.
The uio argument is a pointer to a struct uio as defined by <sys/uio.h>:
struct uio {
struct iovec *uio_iov; /* pointer to array of iovecs */
int uio_iovcnt; /* number of iovecs in array */
off_t uio_offset; /* offset into file this uio corresponds to */
size_t uio_resid; /* residual i/o count */
enum uio_seg uio_segflg;
enum uio_rw uio_rw;
struct proc *uio_procp;/* process if UIO_USERSPACE */
};
A struct uio typically describes data in motion. Several of the fields
described below reflect that expectation.
uio_iov Pointer to array of struct iovecs:
struct iovec {
void *iov_base; /* Base address. */
size_t iov_len; /* Length. */
};
uio_iovcnt The number of iovecs in the array.
uio_offset An offset into the corresponding object.
uio_resid The amount of data remaining to be transferred.
uio_segflg A flag indicating whether the space described is in user-
space (UIO_USERSPACE) or kernel-space (UIO_SYSSPACE).
uio_rw A flag indicating whether date should be read into the space
(UIO_READ) or written from the space (UIO_WRITE).
uio_procp A pointer to the process whose data area is described by the
structure, or NULL if the area is in kernel-space.
The value of uio->uio_rw controls whether uiomove copies data from buf to
uio or vice versa.
The lesser of n or uio->resid bytes are copied.
uiomove changes fields of the structure pointed to by uio, such that
uio->uio_resid is decremented by the amount of data moved, uio-
>uio_offset is incremented by the same amount, and the array of iovecs is
adjusted to point that much farther into the region described. This al-
lows multiple calls to uiomove to easily be used to fill or drain the re-
gion of data.
RETURN VALUES
uiomove returns 0 on success or EFAULT if a bad address is encountered.
SEE ALSOcopy(9)MirOS BSD #10-current February 12, 1999 1
