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