mirror of https://github.com/vbatts/tar-split.git
106 lines
2.7 KiB
Go
106 lines
2.7 KiB
Go
package storage
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import (
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"bytes"
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"errors"
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"hash/crc64"
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"io"
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"os"
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"path/filepath"
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)
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// FileGetter is the interface for getting a stream of a file payload,
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// addressed by name/filename. Presumably, the names will be scoped to relative
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// file paths.
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type FileGetter interface {
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// Get returns a stream for the provided file path
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Get(filename string) (output io.ReadCloser, err error)
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}
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// FilePutter is the interface for storing a stream of a file payload,
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// addressed by name/filename.
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type FilePutter interface {
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// Put returns the size of the stream received, and the crc64 checksum for
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// the provided stream
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Put(filename string, input io.Reader) (size int64, checksum []byte, err error)
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}
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// FileGetPutter is the interface that groups both Getting and Putting file
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// payloads.
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type FileGetPutter interface {
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FileGetter
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FilePutter
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}
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// NewPathFileGetter returns a FileGetter that is for files relative to path
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// relpath.
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func NewPathFileGetter(relpath string) FileGetter {
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return &pathFileGetter{root: relpath}
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}
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type pathFileGetter struct {
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root string
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}
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func (pfg pathFileGetter) Get(filename string) (io.ReadCloser, error) {
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return os.Open(filepath.Join(pfg.root, filename))
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}
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type bufferFileGetPutter struct {
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files map[string][]byte
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}
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func (bfgp bufferFileGetPutter) Get(name string) (io.ReadCloser, error) {
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if _, ok := bfgp.files[name]; !ok {
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return nil, errors.New("no such file")
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}
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b := bytes.NewBuffer(bfgp.files[name])
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return &readCloserWrapper{b}, nil
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}
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func (bfgp *bufferFileGetPutter) Put(name string, r io.Reader) (int64, []byte, error) {
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crc := crc64.New(CRCTable)
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buf := bytes.NewBuffer(nil)
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cw := io.MultiWriter(crc, buf)
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i, err := io.Copy(cw, r)
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if err != nil {
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return 0, nil, err
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}
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bfgp.files[name] = buf.Bytes()
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return i, crc.Sum(nil), nil
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}
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type readCloserWrapper struct {
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io.Reader
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}
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func (w *readCloserWrapper) Close() error { return nil }
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// NewBufferFileGetPutter is a simple in-memory FileGetPutter
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//
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// Implication is this is memory intensive...
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// Probably best for testing or light weight cases.
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func NewBufferFileGetPutter() FileGetPutter {
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return &bufferFileGetPutter{
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files: map[string][]byte{},
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}
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}
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// NewDiscardFilePutter is a bit bucket FilePutter
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func NewDiscardFilePutter() FilePutter {
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return &bitBucketFilePutter{}
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}
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type bitBucketFilePutter struct {
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buffer [32 * 1024]byte // 32 kB is the buffer size currently used by io.Copy, as of August 2021.
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}
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func (bbfp *bitBucketFilePutter) Put(name string, r io.Reader) (int64, []byte, error) {
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c := crc64.New(CRCTable)
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i, err := io.CopyBuffer(c, r, bbfp.buffer[:])
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return i, c.Sum(nil), err
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}
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// CRCTable is the default table used for crc64 sum calculations
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var CRCTable = crc64.MakeTable(crc64.ISO)
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