90 lines
2.7 KiB
Go
90 lines
2.7 KiB
Go
// Copyright 2018 The gVisor Authors.
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//
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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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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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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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package fdpipe
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import (
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"fmt"
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"io/ioutil"
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"gvisor.dev/gvisor/pkg/context"
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"gvisor.dev/gvisor/pkg/sentry/fs"
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"gvisor.dev/gvisor/pkg/sync"
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)
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// beforeSave is invoked by stateify.
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func (p *pipeOperations) beforeSave() {
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if p.flags.Read {
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data, err := ioutil.ReadAll(p.file)
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if err != nil && !isBlockError(err) {
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panic(fmt.Sprintf("failed to read from pipe: %v", err))
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}
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p.readAheadBuffer = append(p.readAheadBuffer, data...)
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} else if p.flags.Write {
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file, err := p.opener.NonBlockingOpen(context.Background(), fs.PermMask{Write: true})
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if err != nil {
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panic(fs.ErrSaveRejection{fmt.Errorf("write-only pipe end cannot be re-opened as %v: %v", p, err)})
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}
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file.Close()
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}
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}
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// saveFlags is invoked by stateify.
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func (p *pipeOperations) saveFlags() fs.FileFlags {
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return p.flags
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}
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// readPipeOperationsLoading is used to ensure that write-only pipe fds are
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// opened after read/write and read-only pipe fds, to avoid ENXIO when
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// multiple pipe fds refer to different ends of the same pipe.
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var readPipeOperationsLoading sync.WaitGroup
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// loadFlags is invoked by stateify.
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func (p *pipeOperations) loadFlags(flags fs.FileFlags) {
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// This is a hack to ensure that readPipeOperationsLoading includes all
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// readable pipe fds before any asynchronous calls to
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// readPipeOperationsLoading.Wait().
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if flags.Read {
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readPipeOperationsLoading.Add(1)
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}
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p.flags = flags
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}
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// afterLoad is invoked by stateify.
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func (p *pipeOperations) afterLoad() {
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load := func() error {
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if !p.flags.Read {
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readPipeOperationsLoading.Wait()
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} else {
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defer readPipeOperationsLoading.Done()
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}
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var err error
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p.file, err = p.opener.NonBlockingOpen(context.Background(), fs.PermMask{
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Read: p.flags.Read,
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Write: p.flags.Write,
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})
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if err != nil {
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return fmt.Errorf("unable to open pipe %v: %v", p, err)
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}
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if err := p.init(); err != nil {
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return fmt.Errorf("unable to initialize pipe %v: %v", p, err)
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}
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return nil
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}
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// Do background opening of pipe ends. Note for write-only pipe ends we
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// have to do it asynchronously to avoid blocking the restore.
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fs.Async(fs.CatchError(load))
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}
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