forked from goodrain/rainbond
/
copyio.go
159 lines (139 loc) · 4.46 KB
/
copyio.go
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// RAINBOND, Application Management Platform
// Copyright (C) 2014-2017 Goodrain Co., Ltd.
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version. For any non-GPL usage of Rainbond,
// one or multiple Commercial Licenses authorized by Goodrain Co., Ltd.
// must be obtained first.
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// You should have received a copy of the GNU General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.
package util
import (
"bytes"
"encoding/binary"
"fmt"
"io"
"sync"
)
// StdType is the type of standard stream
// a writer can multiplex to.
type StdType byte
const (
// Stdin represents standard input stream type.
Stdin StdType = iota
// Stdout represents standard output stream type.
Stdout
// Stderr represents standard error steam type.
Stderr
// Systemerr represents errors originating from the system that make it
// into the the multiplexed stream.
Systemerr
stdWriterPrefixLen = 8
stdWriterFdIndex = 0
stdWriterSizeIndex = 4
startingBufLen = 32*1024 + stdWriterPrefixLen + 1
)
var bufPool = &sync.Pool{New: func() interface{} { return bytes.NewBuffer(nil) }}
// StdCopy is a modified version of io.Copy.
//
// StdCopy will demultiplex `src`, assuming that it contains two streams,
// previously multiplexed together using a StdWriter instance.
// As it reads from `src`, StdCopy will write to `dstout` and `dsterr`.
//
// StdCopy will read until it hits EOF on `src`. It will then return a nil error.
// In other words: if `err` is non nil, it indicates a real underlying error.
//
// `written` will hold the total number of bytes written to `dstout` and `dsterr`.
func StdCopy(dstout, dsterr io.Writer, src io.Reader) (written int64, err error) {
var (
buf = make([]byte, startingBufLen)
bufLen = len(buf)
nr, nw int
er, ew error
out io.Writer
frameSize int
)
for {
// Make sure we have at least a full header
for nr < stdWriterPrefixLen {
var nr2 int
nr2, er = src.Read(buf[nr:])
nr += nr2
if er == io.EOF {
if nr < stdWriterPrefixLen {
return written, nil
}
break
}
if er != nil {
return 0, er
}
}
stream := StdType(buf[stdWriterFdIndex])
// Check the first byte to know where to write
switch stream {
case Stdin:
fallthrough
case Stdout:
// Write on stdout
out = dstout
case Stderr:
// Write on stderr
out = dsterr
case Systemerr:
// If we're on Systemerr, we won't write anywhere.
// NB: if this code changes later, make sure you don't try to write
// to outstream if Systemerr is the stream
out = nil
default:
return 0, fmt.Errorf("Unrecognized input header: %d", buf[stdWriterFdIndex])
}
// Retrieve the size of the frame
frameSize = int(binary.BigEndian.Uint32(buf[stdWriterSizeIndex : stdWriterSizeIndex+4]))
// Check if the buffer is big enough to read the frame.
// Extend it if necessary.
if frameSize+stdWriterPrefixLen > bufLen {
buf = append(buf, make([]byte, frameSize+stdWriterPrefixLen-bufLen+1)...)
bufLen = len(buf)
}
// While the amount of bytes read is less than the size of the frame + header, we keep reading
for nr < frameSize+stdWriterPrefixLen {
var nr2 int
nr2, er = src.Read(buf[nr:])
nr += nr2
if er == io.EOF {
if nr < frameSize+stdWriterPrefixLen {
return written, nil
}
break
}
if er != nil {
return 0, er
}
}
// we might have an error from the source mixed up in our multiplexed
// stream. if we do, return it.
if stream == Systemerr {
return written, fmt.Errorf("error from daemon in stream: %s", string(buf[stdWriterPrefixLen:frameSize+stdWriterPrefixLen]))
}
// Write the retrieved frame (without header)
nw, ew = out.Write(buf[stdWriterPrefixLen : frameSize+stdWriterPrefixLen])
if ew != nil {
return 0, ew
}
// If the frame has not been fully written: error
if nw != frameSize {
return 0, io.ErrShortWrite
}
written += int64(nw)
// Move the rest of the buffer to the beginning
copy(buf, buf[frameSize+stdWriterPrefixLen:])
// Move the index
nr -= frameSize + stdWriterPrefixLen
}
}