add better generate

Signed-off-by: Jess Frazelle <acidburn@microsoft.com>

vendor/github.com/genuinetools/reg/registry/layer.go

@@ -0,0 +1,89 @@
+package registry
+
+import (
+	"io"
+	"net/http"
+	"net/url"
+
+	"github.com/docker/distribution/reference"
+	"github.com/opencontainers/go-digest"
+)
+
+// DownloadLayer downloads a specific layer by digest for a repository.
+func (r *Registry) DownloadLayer(repository string, digest digest.Digest) (io.ReadCloser, error) {
+	url := r.url("/v2/%s/blobs/%s", repository, digest)
+	r.Logf("registry.layer.download url=%s repository=%s digest=%s", url, repository, digest)
+
+	resp, err := r.Client.Get(url)
+	if err != nil {
+		return nil, err
+	}
+
+	return resp.Body, nil
+}
+
+// UploadLayer uploads a specific layer by digest for a repository.
+func (r *Registry) UploadLayer(repository string, digest reference.Reference, content io.Reader) error {
+	uploadURL, err := r.initiateUpload(repository)
+	if err != nil {
+		return err
+	}
+	q := uploadURL.Query()
+	q.Set("digest", digest.String())
+	uploadURL.RawQuery = q.Encode()
+
+	r.Logf("registry.layer.upload url=%s repository=%s digest=%s", uploadURL, repository, digest)
+
+	upload, err := http.NewRequest("PUT", uploadURL.String(), content)
+	if err != nil {
+		return err
+	}
+	upload.Header.Set("Content-Type", "application/octet-stream")
+
+	_, err = r.Client.Do(upload)
+	return err
+}
+
+// HasLayer returns if the registry contains the specific digest for a repository.
+func (r *Registry) HasLayer(repository string, digest digest.Digest) (bool, error) {
+	checkURL := r.url("/v2/%s/blobs/%s", repository, digest)
+	r.Logf("registry.layer.check url=%s repository=%s digest=%s", checkURL, repository, digest)
+
+	resp, err := r.Client.Head(checkURL)
+	if err == nil {
+		defer resp.Body.Close()
+		return resp.StatusCode == http.StatusOK, nil
+	}
+
+	urlErr, ok := err.(*url.Error)
+	if !ok {
+		return false, err
+	}
+	httpErr, ok := urlErr.Err.(*httpStatusError)
+	if !ok {
+		return false, err
+	}
+	if httpErr.Response.StatusCode == http.StatusNotFound {
+		return false, nil
+	}
+
+	return false, err
+}
+
+func (r *Registry) initiateUpload(repository string) (*url.URL, error) {
+	initiateURL := r.url("/v2/%s/blobs/uploads/", repository)
+	r.Logf("registry.layer.initiate-upload url=%s repository=%s", initiateURL, repository)
+
+	resp, err := r.Client.Post(initiateURL, "application/octet-stream", nil)
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+
+	location := resp.Header.Get("Location")
+	locationURL, err := url.Parse(location)
+	if err != nil {
+		return nil, err
+	}
+	return locationURL, nil
+}