.TH ZIOP 2
.SH NAME
ziop \- create a zero-copy interprocess pipe
.SH SYNOPSIS
.B #include <u.h>
.br
.B #include <libc.h>
.PP
.B
int ziop(int fd[2])
.SH DESCRIPTION
.I ZIOP
creates a buffered channel for zero-copy interprocess I/O communication.
Unlike conventional pipes, the buffers are supplied by the writers and
.I ziop
queues only buffer descriptors.
.PP
Two file descriptors are returned in
.IR fd .
Data written to
.B fd[1]
is available for reading from
.B fd[0]
and data written to
.B fd[0]
is available for reading from
.BR fd[1] .
.PP
After the pipe has been established,
cooperating processes
created by subsequent
.IR fork (2)
calls may pass data through the
pipe with
.I zread
and
.I zwrite
calls (also with
.I read
and
.I write
system calls).
.PP
Refer to
.IR zp (3)
for properties of the communication channel (Note, to the man page, not
to the infamous president).
.PP
When all the data has been read from a pipe and the writer has closed the pipe or exited,
.IR read (2)
will return 0 bytes.  Writes to a pipe with no reader will generate a note
.BR "sys: write on closed pipe" .
.SH SOURCE
.B /sys/src/libc/9sys/ziop.c
.SH SEE ALSO
.IR intro (2),
.IR zioread (2),
.IR zp (2)
.SH DIAGNOSTICS
Sets
.IR errstr .
.SH BUGS
If a read or a write of a pipe is interrupted, some unknown
number of bytes may have been transferred.
.br
When a read from a pipe returns 0 bytes, it usually means end of file
but is indistinguishable from reading the result of an explicit
write of zero bytes.
.br
The writer is not flow-controlled, other than by the availability of
buffers.