tar: mv the Getter to tar/storage

tar/storage/getter.go

@@ -0,0 +1,98 @@
+package storage
+
+import (
+	"bytes"
+	"errors"
+	"hash/crc64"
+	"io"
+	"io/ioutil"
+	"os"
+	"path"
+)
+
+type FileGetter interface {
+	// Get returns a stream for the provided file path
+	Get(string) (io.ReadCloser, error)
+}
+
+type FilePutter interface {
+	// Put returns the crc64 checksum for the provided file
+	Put(string, io.Reader) (int64, []byte, error)
+}
+
+type FileGetPutter interface {
+	FileGetter
+	FilePutter
+}
+
+// NewPathFileGetter returns a FileGetter that is for files relative to path relpath.
+func NewPathFileGetter(relpath string) FileGetter {
+	return &pathFileGetter{root: relpath}
+}
+
+type pathFileGetter struct {
+	root string
+}
+
+func (pfg pathFileGetter) Get(filename string) (io.ReadCloser, error) {
+	// FIXME might should have a check for '../../../../etc/passwd' attempts?
+	return os.Open(path.Join(pfg.root, filename))
+}
+
+type bufferFileGetPutter struct {
+	files map[string][]byte
+}
+
+func (bfgp bufferFileGetPutter) Get(name string) (io.ReadCloser, error) {
+	if _, ok := bfgp.files[name]; !ok {
+		return nil, errors.New("no such file")
+	}
+	b := bytes.NewBuffer(bfgp.files[name])
+	return &readCloserWrapper{b}, nil
+}
+
+func (bfgp *bufferFileGetPutter) Put(name string, r io.Reader) (int64, []byte, error) {
+	c := crc64.New(CRCTable)
+	tRdr := io.TeeReader(r, c)
+	b := bytes.NewBuffer([]byte{})
+	i, err := io.Copy(b, tRdr)
+	if err != nil {
+		return 0, nil, err
+	}
+	bfgp.files[name] = b.Bytes()
+	return i, c.Sum(nil), nil
+}
+
+type readCloserWrapper struct {
+	io.Reader
+}
+
+func (w *readCloserWrapper) Close() error { return nil }
+
+// NewBufferFileGetPutter is simple in memory FileGetPutter
+//
+// Implication is this is memory intensive...
+// Probably best for testing or light weight cases.
+func NewBufferFileGetPutter() FileGetPutter {
+	return &bufferFileGetPutter{
+		files: map[string][]byte{},
+	}
+}
+
+// NewDiscardFilePutter is a bit bucket FilePutter
+func NewDiscardFilePutter() FilePutter {
+	return &bitBucketFilePutter{}
+}
+
+type bitBucketFilePutter struct {
+}
+
+func (bbfp *bitBucketFilePutter) Put(name string, r io.Reader) (int64, []byte, error) {
+	c := crc64.New(CRCTable)
+	tRdr := io.TeeReader(r, c)
+	i, err := io.Copy(ioutil.Discard, tRdr)
+	return i, c.Sum(nil), err
+}
+
+// CRCTable is the default table used for crc64 sum calculations
+var CRCTable = crc64.MakeTable(crc64.ISO)

tar/storage/getter_test.go

@@ -0,0 +1,62 @@
+package storage
+
+import (
+	"bytes"
+	"io/ioutil"
+	"testing"
+)
+
+func TestGetter(t *testing.T) {
+	fgp := NewBufferFileGetPutter()
+	files := map[string]map[string][]byte{
+		"file1.txt": {"foo": []byte{60, 60, 48, 48, 0, 0, 0, 0}},
+		"file2.txt": {"bar": []byte{45, 196, 22, 240, 0, 0, 0, 0}},
+	}
+	for n, b := range files {
+		for body, sum := range b {
+			_, csum, err := fgp.Put(n, bytes.NewBufferString(body))
+			if err != nil {
+				t.Error(err)
+			}
+			if !bytes.Equal(csum, sum) {
+				t.Errorf("checksum: expected 0x%x; got 0x%x", sum, csum)
+			}
+		}
+	}
+	for n, b := range files {
+		for body := range b {
+			r, err := fgp.Get(n)
+			if err != nil {
+				t.Error(err)
+			}
+			buf, err := ioutil.ReadAll(r)
+			if err != nil {
+				t.Error(err)
+			}
+			if body != string(buf) {
+				t.Errorf("expected %q, got %q", body, string(buf))
+			}
+		}
+	}
+}
+func TestPutter(t *testing.T) {
+	fp := NewDiscardFilePutter()
+	// map[filename]map[body]crc64sum
+	files := map[string]map[string][]byte{
+		"file1.txt": {"foo": []byte{60, 60, 48, 48, 0, 0, 0, 0}},
+		"file2.txt": {"bar": []byte{45, 196, 22, 240, 0, 0, 0, 0}},
+		"file3.txt": {"baz": []byte{32, 68, 22, 240, 0, 0, 0, 0}},
+		"file4.txt": {"bif": []byte{48, 9, 150, 240, 0, 0, 0, 0}},
+	}
+	for n, b := range files {
+		for body, sum := range b {
+			_, csum, err := fp.Put(n, bytes.NewBufferString(body))
+			if err != nil {
+				t.Error(err)
+			}
+			if !bytes.Equal(csum, sum) {
+				t.Errorf("checksum on %q: expected %v; got %v", n, sum, csum)
+			}
+		}
+	}
+}