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VOP_RDWR(9)		 BSD Kernel Developer's	Manual		   VOP_RDWR(9)

NAME
     VOP_READ, VOP_WRITE -- read or write a file

SYNOPSIS
     #include <sys/param.h>
     #include <sys/vnode.h>
     #include <sys/uio.h>

     int
     VOP_READ(struct vnode *vp,	struct uio *uio, int ioflag,
	 struct	ucred *cred);

     int
     VOP_WRITE(struct vnode *vp, struct	uio *uio, int ioflag,
	 struct	ucred *cred);

DESCRIPTION
     These entry points	read or	write the contents of a	file

     The arguments are:

     vp	     The vnode of the file.

     uio     The location of the data to be read or written.

     ioflag  Various flags.

     cnp     The credentials of	the caller.

     The ioflag	argument is used to give directives and	hints to the file sys-
     tem.  When	attempting a read, the high 16 bits are	used to	provide	a
     read-ahead	hint (in units of file system blocks) that the file system
     should attempt.  The low 16 bits are a bit	mask which can contain the
     following flags:

     IO_UNIT	    Do I/O as atomic unit.

     IO_APPEND	    Append write to end.

     IO_SYNC	    Do I/O synchronously.

     IO_NODELOCKED  Underlying node already locked.

     IO_NDELAY	    FNDELAY flag set in	file table.

     IO_VMIO	    Data already in VMIO space.

LOCKS
     The file should be	locked on entry	and will still be locked on exit.

RETURN VALUES
     Zero is returned on success, otherwise an error code is returned.

ERRORS
     [EFBIG]		An attempt was made to write a file that exceeds the
			process's file size limit or the maximum file size.

     [ENOSPC]		The file system	is full.

     [EPERM]		An append-only flag is set on the file,	but the	caller
			is attempting to write before the current end of file.

SEE ALSO
     uiomove(9), vnode(9)

AUTHORS
     This manual page was written by Doug Rabson.

BSD				 July 24, 1996				   BSD

NAME | SYNOPSIS | DESCRIPTION | LOCKS | RETURN VALUES | ERRORS | SEE ALSO | AUTHORS

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