.Fa d
into the buffer pointed to by
.Fa buf .
-.Fn Readv
+.Fn \ Readv
performs the same action, but scatters the input data
into the
.Fa iovcnt
the descriptor references a normal file that has that many bytes left
before the end-of-file, but in no other case.
.Pp
+Note that
+.Fn readv
+will fail if the value of
+.Fa iovcnt
+exceedes the constant
+.Fa UIO_MAXIOV .
+.Pp
.Sh RETURN VALUES
If successful, the
number of bytes actually read is returned. Upon reading end-of-file,
.It Bq Er EINVAL
.Fa Iovcnt
was less than or equal to 0, or greater than
-.Dv {UIO_MAXIOV} .
+.\".Dv {UIO_MAXIOV} .
+.Fa UIO_MAXIOV
.It Bq Er EINVAL
One of the
.Fa iov_len
of data to the object referenced by the descriptor
.Fa d
from the buffer pointed to by
-.Fa buf .
-.Fn Writev
+.Fa buf .
+.Fn \ Writev
performs the same action, but gathers the output data
from the
.Fa iovcnt
may write fewer bytes than requested;
the return value must be noted,
and the remainder of the operation should be retried when possible.
+.Pp
+Note that
+.Fn writev
+will fail if the value of
+.Fa iovcnt
+exceedes the constant
+.Fa UIO_MAXIOV .
.Sh RETURN VALUES
Upon successful completion the number of bytes which were written
is returned. Otherwise a -1 is returned and the global variable
.It Bq Er EINVAL
.Fa Iovcnt
was less than or equal to 0, or greater than
-.Dv {UIO_MAXIOV} .
+.Fa UIO_MAXIOV .
.It Bq Er EINVAL
One of the
.Fa iov_len