Rename layer files to blob

Signed-off-by: Derek McGowan <derek@mcgstyle.net> (github: dmcgowan)

registry/client/blob.go

@@ -0,0 +1,159 @@
+package client
+
+import (
+	"bufio"
+	"bytes"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"net/http"
+	"os"
+
+	"github.com/docker/distribution"
+	"github.com/docker/distribution/context"
+)
+
+type httpBlob struct {
+	*repository
+
+	desc distribution.Descriptor
+
+	rc     io.ReadCloser // remote read closer
+	brd    *bufio.Reader // internal buffered io
+	offset int64
+	err    error
+}
+
+func (hb *httpBlob) Read(p []byte) (n int, err error) {
+	if hb.err != nil {
+		return 0, hb.err
+	}
+
+	rd, err := hb.reader()
+	if err != nil {
+		return 0, err
+	}
+
+	n, err = rd.Read(p)
+	hb.offset += int64(n)
+
+	// Simulate io.EOF error if we reach filesize.
+	if err == nil && hb.offset >= hb.desc.Length {
+		err = io.EOF
+	}
+
+	return n, err
+}
+
+func (hb *httpBlob) Seek(offset int64, whence int) (int64, error) {
+	if hb.err != nil {
+		return 0, hb.err
+	}
+
+	var err error
+	newOffset := hb.offset
+
+	switch whence {
+	case os.SEEK_CUR:
+		newOffset += int64(offset)
+	case os.SEEK_END:
+		newOffset = hb.desc.Length + int64(offset)
+	case os.SEEK_SET:
+		newOffset = int64(offset)
+	}
+
+	if newOffset < 0 {
+		err = fmt.Errorf("cannot seek to negative position")
+	} else {
+		if hb.offset != newOffset {
+			hb.reset()
+		}
+
+		// No problems, set the offset.
+		hb.offset = newOffset
+	}
+
+	return hb.offset, err
+}
+
+func (hb *httpBlob) Close() error {
+	if hb.err != nil {
+		return hb.err
+	}
+
+	// close and release reader chain
+	if hb.rc != nil {
+		hb.rc.Close()
+	}
+
+	hb.rc = nil
+	hb.brd = nil
+
+	hb.err = fmt.Errorf("httpBlob: closed")
+
+	return nil
+}
+
+func (hb *httpBlob) reset() {
+	if hb.err != nil {
+		return
+	}
+	if hb.rc != nil {
+		hb.rc.Close()
+		hb.rc = nil
+	}
+}
+
+func (hb *httpBlob) reader() (io.Reader, error) {
+	if hb.err != nil {
+		return nil, hb.err
+	}
+
+	if hb.rc != nil {
+		return hb.brd, nil
+	}
+
+	// If the offset is great than or equal to size, return a empty, noop reader.
+	if hb.offset >= hb.desc.Length {
+		return ioutil.NopCloser(bytes.NewReader([]byte{})), nil
+	}
+
+	blobURL, err := hb.ub.BuildBlobURL(hb.name, hb.desc.Digest)
+	if err != nil {
+		return nil, err
+	}
+
+	req, err := http.NewRequest("GET", blobURL, nil)
+	if err != nil {
+		return nil, err
+	}
+
+	if hb.offset > 0 {
+		// TODO(stevvooe): Get this working correctly.
+
+		// If we are at different offset, issue a range request from there.
+		req.Header.Add("Range", fmt.Sprintf("1-"))
+		context.GetLogger(hb.context).Infof("Range: %s", req.Header.Get("Range"))
+	}
+
+	resp, err := hb.client.Do(req)
+	if err != nil {
+		return nil, err
+	}
+
+	switch {
+	case resp.StatusCode == 200:
+		hb.rc = resp.Body
+	default:
+		defer resp.Body.Close()
+		return nil, fmt.Errorf("unexpected status resolving reader: %v", resp.Status)
+	}
+
+	if hb.brd == nil {
+		hb.brd = bufio.NewReader(hb.rc)
+	} else {
+		hb.brd.Reset(hb.rc)
+	}
+
+	return hb.brd, nil
+}