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https://github.com/gravitational/teleport
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be8d931877
`SyncBuffer` has a goroutine running `io.Copy` to read from the underlying pipe. Close stops the pipe, but doesn't wait for the last chunk of data to be written by `io.Copy` to the buffer. Both `Bytes` and `String` assume that the buffer received no further writes after `Close`. Add explicit synchronization between `io.Copy` goroutine and `Close`.
83 lines
1.9 KiB
Go
83 lines
1.9 KiB
Go
/*
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Copyright 2018 Gravitational, Inc.
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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 utils
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import (
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"bytes"
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"io"
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)
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// NewSyncBuffer returns new in memory buffer
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func NewSyncBuffer() *SyncBuffer {
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reader, writer := io.Pipe()
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buf := &bytes.Buffer{}
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copyDone := make(chan struct{})
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go func() {
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defer close(copyDone)
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io.Copy(buf, reader)
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}()
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return &SyncBuffer{
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reader: reader,
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writer: writer,
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buf: buf,
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copyDone: copyDone,
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}
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}
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// SyncBuffer is in memory bytes buffer that is
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// safe for concurrent writes
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type SyncBuffer struct {
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reader *io.PipeReader
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writer *io.PipeWriter
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buf *bytes.Buffer
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// copyDone makes SyncBuffer.Close block until io.Copy goroutine finishes.
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// This prevents data races between io.Copy and SyncBuffer.String/Bytes.
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copyDone chan struct{}
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}
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func (b *SyncBuffer) Write(data []byte) (n int, err error) {
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return b.writer.Write(data)
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}
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// String returns contents of the buffer
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// after this call, all writes will fail
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func (b *SyncBuffer) String() string {
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b.Close()
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return b.buf.String()
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}
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// Bytes returns contents of the buffer
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// after this call, all writes will fail
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func (b *SyncBuffer) Bytes() []byte {
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b.Close()
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return b.buf.Bytes()
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}
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// Close closes reads and writes on the buffer
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func (b *SyncBuffer) Close() error {
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err := b.reader.Close()
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err2 := b.writer.Close()
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// Explicitly wait for io.Copy goroutine to finish.
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<-b.copyDone
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if err != nil {
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return err
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}
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return err2
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}
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