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// Copyright 2016 syzkaller project authors. All rights reserved.
// Use of this source code is governed by Apache 2 LICENSE that can be found in the LICENSE file.
package vmimpl
import (
"bytes"
"context"
"fmt"
"io"
"sync"
"golang.org/x/sync/errgroup"
)
type OutputType int
const (
OutputConsole OutputType = iota
OutputStdout
OutputStderr
)
type Chunk struct {
Data []byte
Type OutputType
}
type decoderState struct {
done chan struct{} // Closed when the decoder exits.
err error
}
type OutputMerger struct {
Output chan Chunk
decoderErr map[string]*decoderState
teeMu sync.Mutex
tee io.Writer
wg sync.WaitGroup
}
type MergerError struct {
Name string
R io.ReadCloser
Err error
}
func (err MergerError) Error() string {
return fmt.Sprintf("failed to read from %v: %v", err.Name, err.Err)
}
func NewOutputMerger(tee io.Writer) *OutputMerger {
return &OutputMerger{
Output: make(chan Chunk, 1000),
decoderErr: map[string]*decoderState{},
tee: tee,
}
}
func (merger *OutputMerger) Wait() {
merger.wg.Wait()
close(merger.Output)
}
// Errors returns a channel that will receive errors from the curretly active decoderErr.
func (merger *OutputMerger) Errors(ctx context.Context) <-chan error {
eg, egCtx := errgroup.WithContext(ctx)
for _, decoder := range merger.decoderErr {
eg.Go(func() error {
select {
case <-egCtx.Done():
return nil
case <-decoder.done:
return decoder.err
}
})
}
ret := make(chan error, 1)
go func() {
err := eg.Wait()
if err != nil {
ret <- err
}
close(ret)
}()
return ret
}
func (merger *OutputMerger) Add(name string, typ OutputType, r io.ReadCloser) {
merger.AddDecoder(name, typ, r, nil)
}
func (merger *OutputMerger) AddDecoder(name string, typ OutputType, r io.ReadCloser,
decoder func(data []byte) (start, size int, decoded []byte)) {
state := &decoderState{
done: make(chan struct{}),
}
merger.decoderErr[name] = state
merger.wg.Add(1)
go func() {
defer merger.wg.Done()
defer close(state.done)
err := merger.runDecoder(typ, r, decoder)
state.err = MergerError{name, r, err}
}()
}
func (merger *OutputMerger) runDecoder(typ OutputType, r io.ReadCloser,
decoder func(data []byte) (start, size int, decoded []byte)) error {
var pending []byte
var proto []byte
var buf [4 << 10]byte
for {
n, err := r.Read(buf[:])
if n != 0 {
if decoder != nil {
proto = append(proto, buf[:n]...)
start, size, decoded := decoder(proto)
proto = proto[start+size:]
if len(decoded) != 0 {
merger.Output <- Chunk{decoded, typ} // note: this can block
}
}
// Remove all carriage returns.
buf := buf[:n]
if bytes.IndexByte(buf, '\r') != -1 {
buf = bytes.ReplaceAll(buf, []byte("\r"), nil)
}
pending = append(pending, buf...)
if pos := bytes.LastIndexByte(pending, '\n'); pos != -1 {
out := pending[:pos+1]
if merger.tee != nil {
merger.teeMu.Lock()
merger.tee.Write(out)
merger.teeMu.Unlock()
}
select {
case merger.Output <- Chunk{append([]byte{}, out...), typ}:
r := copy(pending, pending[pos+1:])
pending = pending[:r]
default:
}
}
}
if err != nil {
if len(pending) != 0 {
pending = append(pending, '\n')
if merger.tee != nil {
merger.teeMu.Lock()
merger.tee.Write(pending)
merger.teeMu.Unlock()
}
select {
case merger.Output <- Chunk{pending, typ}:
default:
}
}
r.Close()
return err
}
}
}
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