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// +build go1.12
/*
Copyright The containerd Authors.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
package fifo
import (
"syscall"
)
// SyscallConn provides raw access to the fifo's underlying filedescrptor.
// See syscall.Conn for guarantees provided by this interface.
func (f *fifo) SyscallConn() (syscall.RawConn, error) {
// deterministic check for closed
select {
case <-f.closed:
return nil, ErrClosed
default:
}
select {
case <-f.closed:
return nil, ErrClosed
case <-f.opened:
return f.file.SyscallConn()
default:
}
// Not opened and not closed, this means open is non-blocking AND it's not open yet
// Use rawConn to deal with non-blocking open.
rc := &rawConn{f: f, ready: make(chan struct{})}
go func() {
select {
case <-f.closed:
return
case <-f.opened:
rc.raw, rc.err = f.file.SyscallConn()
close(rc.ready)
}
}()
return rc, nil
}
type rawConn struct {
f *fifo
ready chan struct{}
raw syscall.RawConn
err error
}
func (r *rawConn) Control(f func(fd uintptr)) error {
select {
case <-r.f.closed:
return ErrCtrlClosed
case <-r.ready:
}
if r.err != nil {
return r.err
}
return r.raw.Control(f)
}
func (r *rawConn) Read(f func(fd uintptr) (done bool)) error {
if r.f.flag&syscall.O_WRONLY > 0 {
return ErrRdFrmWRONLY
}
select {
case <-r.f.closed:
return ErrReadClosed
case <-r.ready:
}
if r.err != nil {
return r.err
}
return r.raw.Read(f)
}
func (r *rawConn) Write(f func(fd uintptr) (done bool)) error {
if r.f.flag&(syscall.O_WRONLY|syscall.O_RDWR) == 0 {
return ErrWrToRDONLY
}
select {
case <-r.f.closed:
return ErrWriteClosed
case <-r.ready:
}
if r.err != nil {
return r.err
}
return r.raw.Write(f)
}
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