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// Copyright 2018 Netflix, Inc.
//
// 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 expect
import (
"io"
"os"
"time"
)
// PassthroughPipe is pipes data from a io.Reader and allows setting a read
// deadline. If a timeout is reached the error is returned, otherwise the error
// from the provided io.Reader is returned is passed through instead.
type PassthroughPipe struct {
reader *os.File
errC chan error
}
// NewPassthroughPipe returns a new pipe for a io.Reader that passes through
// non-timeout errors.
func NewPassthroughPipe(reader io.Reader) (*PassthroughPipe, error) {
pipeReader, pipeWriter, err := os.Pipe()
if err != nil {
return nil, err
}
errC := make(chan error, 1)
go func() {
defer close(errC)
_, readerErr := io.Copy(pipeWriter, reader)
if readerErr == nil {
// io.Copy reads from reader until EOF, and a successful Copy returns
// err == nil. We set it back to io.EOF to surface the error to Expect.
readerErr = io.EOF
}
// Closing the pipeWriter will unblock the pipeReader.Read.
err = pipeWriter.Close()
if err != nil {
// If we are unable to close the pipe, and the pipe isn't already closed,
// the caller will hang indefinitely.
panic(err)
return
}
// When an error is read from reader, we need it to passthrough the err to
// callers of (*PassthroughPipe).Read.
errC <- readerErr
}()
return &PassthroughPipe{
reader: pipeReader,
errC: errC,
}, nil
}
func (pp *PassthroughPipe) Read(p []byte) (n int, err error) {
n, err = pp.reader.Read(p)
if err != nil {
if os.IsTimeout(err) {
return n, err
}
// If the pipe is closed, this is the second time calling Read on
// PassthroughPipe, so just return the error from the os.Pipe io.Reader.
perr, ok := <-pp.errC
if !ok {
return n, err
}
return n, perr
}
return n, nil
}
func (pp *PassthroughPipe) Close() error {
return pp.reader.Close()
}
func (pp *PassthroughPipe) SetReadDeadline(t time.Time) error {
return pp.reader.SetReadDeadline(t)
}
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