Fix various compile warnings

[splice.git] / splice.2

.TH splice 2 2006-04-28 "Linux 2.6.17" "Linux Programmer's Manual"
.SH NAME
splice \- splice data to/from a pipe.
.SH SYNOPSIS
.B #include <sys/splice.h>

.B long splice(int fd_in, loff_t *off_in, int fd_out, loff_t *off_out, size_t bytes, unsigned int flags);

.SH DESCRIPTION
The act of splicing can be seen as a way to connect two ends of a rope
through a kernel buffer, where that buffer is implemented as a pipe. It
provides a means to move data around without copying it to/from kernel/user
address space, basically a random kernel buffer that the user has full
control over.

The
.BR splice ()
function splices
.I bytes
of  data between file descriptor
.I fd_in
and
.IR fd_out ,
where one of the descriptors must refer to a pipe. The
.I flags
argument is a series of modifier flags:

.TP 1.9i
.B SPLICE_F_MOVE
Attempt to move pages instead of copying. This is only a hint to the kernel,
pages may still be copied if we fail in stealing it out of the pipe or if
the pipe buffers don't refer to full pages.
.TP
.B SPLICE_F_NONBLOCK
Do not block on io.
.TP
.B SPLICE_F_MORE
More data will be coming in a subsequent splice. This is a helpful hint when
the output descriptor refers to a socket, see also
.B MSG_MORE
(see
.BR send (2)
and
.B TCP_CORK
.BR tcp (7))
.TP
.B SPLICE_F_GIFT
See
.BR vmsplice (2).

.SH RETURN VALUE
Upon successful completion,
.BR splice ()
shall return the number of bytes
spliced to or from the pipe. Otherwise, it shall return a value of -1 and
.I errno
shall be set to indicate an error.

.SH ERRORS
.TP 1.1i
.B EBADF
File descriptors either not valid, or do not have proper rw permission.
.TP
.B EINVAL
Target file system doesn't support splicing, none of the descriptors refer
to a pipe or offset given for non-seekable device.
.TP
.B ENOMEM
Ran out of memory.

.SH HISTORY
The
.BR splice (2)
system call first appeared in Linux-2.6.17.

.SH SEE ALSO
.BR splice (2),
.BR tee (2)

.SH AUTHORS
Jens Axboe <axboe@kernel.dk>