130 lines
2.9 KiB
Go
130 lines
2.9 KiB
Go
package asm
|
|
|
|
import (
|
|
"bytes"
|
|
"fmt"
|
|
"hash"
|
|
"hash/crc64"
|
|
"io"
|
|
"sync"
|
|
|
|
"github.com/vbatts/tar-split/tar/storage"
|
|
)
|
|
|
|
// NewOutputTarStream returns an io.ReadCloser that is an assembled tar archive
|
|
// stream.
|
|
//
|
|
// It takes a storage.FileGetter, for mapping the file payloads that are to be read in,
|
|
// and a storage.Unpacker, which has access to the rawbytes and file order
|
|
// metadata. With the combination of these two items, a precise assembled Tar
|
|
// archive is possible.
|
|
func NewOutputTarStream(fg storage.FileGetter, up storage.Unpacker) io.ReadCloser {
|
|
// ... Since these are interfaces, this is possible, so let's not have a nil pointer
|
|
if fg == nil || up == nil {
|
|
return nil
|
|
}
|
|
pr, pw := io.Pipe()
|
|
go func() {
|
|
err := WriteOutputTarStream(fg, up, pw)
|
|
if err != nil {
|
|
pw.CloseWithError(err)
|
|
} else {
|
|
pw.Close()
|
|
}
|
|
}()
|
|
return pr
|
|
}
|
|
|
|
// WriteOutputTarStream writes assembled tar archive to a writer.
|
|
func WriteOutputTarStream(fg storage.FileGetter, up storage.Unpacker, w io.Writer) error {
|
|
// ... Since these are interfaces, this is possible, so let's not have a nil pointer
|
|
if fg == nil || up == nil {
|
|
return nil
|
|
}
|
|
var copyBuffer []byte
|
|
var crcHash hash.Hash
|
|
var crcSum []byte
|
|
var multiWriter io.Writer
|
|
for {
|
|
entry, err := up.Next()
|
|
if err != nil {
|
|
if err == io.EOF {
|
|
return nil
|
|
}
|
|
return err
|
|
}
|
|
switch entry.Type {
|
|
case storage.SegmentType:
|
|
if _, err := w.Write(entry.Payload); err != nil {
|
|
return err
|
|
}
|
|
case storage.FileType:
|
|
if entry.Size == 0 {
|
|
continue
|
|
}
|
|
fh, err := fg.Get(entry.GetName())
|
|
if err != nil {
|
|
return err
|
|
}
|
|
if crcHash == nil {
|
|
crcHash = crc64.New(storage.CRCTable)
|
|
crcSum = make([]byte, 8)
|
|
multiWriter = io.MultiWriter(w, crcHash)
|
|
copyBuffer = byteBufferPool.Get().([]byte)
|
|
defer byteBufferPool.Put(copyBuffer)
|
|
} else {
|
|
crcHash.Reset()
|
|
}
|
|
|
|
if _, err := copyWithBuffer(multiWriter, fh, copyBuffer); err != nil {
|
|
fh.Close()
|
|
return err
|
|
}
|
|
|
|
if !bytes.Equal(crcHash.Sum(crcSum[:0]), entry.Payload) {
|
|
// I would rather this be a comparable ErrInvalidChecksum or such,
|
|
// but since it's coming through the PipeReader, the context of
|
|
// _which_ file would be lost...
|
|
fh.Close()
|
|
return fmt.Errorf("file integrity checksum failed for %q", entry.GetName())
|
|
}
|
|
fh.Close()
|
|
}
|
|
}
|
|
}
|
|
|
|
var byteBufferPool = &sync.Pool{
|
|
New: func() interface{} {
|
|
return make([]byte, 32*1024)
|
|
},
|
|
}
|
|
|
|
// copyWithBuffer is taken from stdlib io.Copy implementation
|
|
// https://github.com/golang/go/blob/go1.5.1/src/io/io.go#L367
|
|
func copyWithBuffer(dst io.Writer, src io.Reader, buf []byte) (written int64, err error) {
|
|
for {
|
|
nr, er := src.Read(buf)
|
|
if nr > 0 {
|
|
nw, ew := dst.Write(buf[0:nr])
|
|
if nw > 0 {
|
|
written += int64(nw)
|
|
}
|
|
if ew != nil {
|
|
err = ew
|
|
break
|
|
}
|
|
if nr != nw {
|
|
err = io.ErrShortWrite
|
|
break
|
|
}
|
|
}
|
|
if er == io.EOF {
|
|
break
|
|
}
|
|
if er != nil {
|
|
err = er
|
|
break
|
|
}
|
|
}
|
|
return written, err
|
|
}
|