uio(9s) [osf1 man page]

uio(9s) 																   uio(9s)

NAME

       uio - General: Describes I/O, either single vector or multiple vectors

SYNOPSIS

       -----------------------------
       Member Name   Data Type
       -----------------------------
       uio_iov	     struct iovec *
       uio_iovcnt    int
       uio_offset    off_t
       uio_segflg    enum uio_seg
       uio_resid     int
       uio_rw	     enum uio_rw
       -----------------------------

MEMBERS

       Specifies  a  pointer  to the first iovec structure. The iovec structure has two members: one that specifies the address of the segment and
       another that specifies the size of the segment. The system allocates contiguous iovec structures for a given transfer.  Specifies the  num-
       ber  of	iovec  structures for this transfer.  Specifies the offset within the file.  Specifies the segment type. This member can be set to
       one of the following values: UIO_USERSPACE (the segment is from the user data space), UIO_SYSSPACE (the segment is from the system  space),
       or  UIO_USERISPACE  (the  segment  is  from the user I space).  Specifies the number of bytes that still need to be transferred.  Specifies
       whether the transfer is a read or a write. This member is set by read and write system calls according to the corresponding  field  in  the
       file  descriptor. This member can be set to one of the following values: UIO_READ (read transfer), UIO_WRITE (write transfer), or UIO_AIORW
       (Alpha I/O read/write transfer).

DESCRIPTION

       The uio data structure describes, either singler-vector or multiple-vector I/O. Typically, kernel modules do not manipulate the members	of
       this  data structure. However, the data structure is presented here for the purpose of understanding the uiomove routine, which operates on
       the members of the uio structure.

FILES

SEE ALSO

       Routines: uiomove(9r)

																	   uio(9s)

uiomove(9F)						   Kernel Functions for Drivers 					       uiomove(9F)

NAME

       uiomove - copy kernel data using uio structure

SYNOPSIS

       #include <sys/types.h>
       #include <sys/uio.h>

       int uiomove(caddr_t address, size_t nbytes, enum uio_rw rwflag, uio_t *uio_p);

INTERFACE LEVEL

       Architecture independent level 1 (DDI/DKI).

PARAMETERS

       address	       Source/destination kernel address of the copy.

       nbytes	       Number of bytes to copy.

       rwflag	       Flag indicating read or write operation. Possible values are UIO_READ and UIO_WRITE.

       uio_p	       Pointer to the uio structure for the copy.

DESCRIPTION

       The uiomove() function copies nbytes of data to or from the space defined by the uio structure (described in uio(9S)) and the driver.

       The  uio_segflg	member	of the uio(9S) structure determines the type of space to or from which the transfer is being made. If it is set to
       UIO_SYSSPACE, the data transfer is between addresses in the kernel. If it is set to UIO_USERSPACE, the transfer is between a  user  program
       and kernel space.

       rwflag indicates the direction of the transfer. If UIO_READ is set, the data will be transferred from address to the buffer(s) described by
       uio_p. If UIO_WRITE is set, the data will be transferred from the buffer(s) described by uio_p to address.

       In addition to moving the data, uiomove() adds the number of bytes moved to the iov_base member of the iovec(9S) structure,  decreases  the
       iov_len member, increases the uio_offset member of the
	uio(9S) structure, and decreases the uio_resid member.

       This function automatically handles page faults. nbytes does not have to be word-aligned.

RETURN VALUES

       uiomove() returns 0 upon success or EFAULT on failure.

CONTEXT

       User context only, if uio_segflg is set to UIO_USERSPACE. User or interrupt context, if uio_segflg is set to UIO_SYSSPACE.

SEE ALSO

       ureadc(9F), uwritec(9F), iovec(9S), uio(9S)

       Writing Device Drivers

WARNINGS

       If uio_segflg is set to UIO_SYSSPACE and address is selected from user space, the system may panic.

SunOS 5.10							    7 Feb 2003							       uiomove(9F)