Remove trailing punctuation from error messages

golint nowadays rejects it with
> error strings should not be capitalized or end with punctuation or a newline

(… but it accepts leading capitalization anyway, so this does not change
any of the many instances of that.)

Signed-off-by: Miloslav Trmač <mitr@redhat.com>

directory/directory_src.go

@@ -41,7 +41,7 @@ func (s *dirImageSource) GetManifest() ([]byte, string, error) {
 }
 
 func (s *dirImageSource) GetTargetManifest(digest string) ([]byte, string, error) {
-	return nil, "", fmt.Errorf("Getting target manifest not supported by dir:")
+	return nil, "", fmt.Errorf(`Getting target manifest not supported by "dir:"`)
 }
 
 // GetBlob returns a stream for the specified blob, and the blob’s size (or -1 if unknown).

docker/daemon/daemon_dest.go

@@ -128,7 +128,7 @@ func (d *daemonImageDestination) ShouldCompressLayers() bool {
 // If stream.Read() at any time, ESPECIALLY at end of input, returns an error, PutBlob MUST 1) fail, and 2) delete any data stored so far.
 func (d *daemonImageDestination) PutBlob(stream io.Reader, inputInfo types.BlobInfo) (types.BlobInfo, error) {
 	if inputInfo.Digest == "" {
-		return types.BlobInfo{}, fmt.Errorf("Can not stream a blob with unknown digest to docker-daemon:")
+		return types.BlobInfo{}, fmt.Errorf(`"Can not stream a blob with unknown digest to "docker-daemon:"`)
 	}
 
 	if inputInfo.Size == -1 { // Ouch, we need to stream the blob into a temporary file just to determine the size.

docker/daemon/daemon_src.go

@@ -331,7 +331,7 @@ func (s *daemonImageSource) GetManifest() ([]byte, string, error) {
 // out of a manifest list.
 func (s *daemonImageSource) GetTargetManifest(digest string) ([]byte, string, error) {
 	// How did we even get here? GetManifest() above has returned a manifest.DockerV2Schema2MediaType.
-	return nil, "", fmt.Errorf("Manifests list are not supported by docker-daemon:")
+	return nil, "", fmt.Errorf(`Manifest lists are not supported by "docker-daemon:"`)
 }
 
 // GetBlob returns a stream for the specified blob, and the blob’s size (or -1 if unknown).

docker/docker_image_dest.go

@@ -263,7 +263,7 @@ func (d *dockerImageDestination) putOneSignature(url *url.URL, signature []byte)
 		return nil
 
 	case "http", "https":
-		return fmt.Errorf("Writing directly to a %s sigstore %s is not supported. Configure a sigstore-staging: location.", url.Scheme, url.String())
+		return fmt.Errorf("Writing directly to a %s sigstore %s is not supported. Configure a sigstore-staging: location", url.Scheme, url.String())
 	default:
 		return fmt.Errorf("Unsupported scheme when writing signature to %s", url.String())
 	}
@@ -282,7 +282,7 @@ func (c *dockerClient) deleteOneSignature(url *url.URL) (missing bool, err error
 		return false, err
 
 	case "http", "https":
-		return false, fmt.Errorf("Writing directly to a %s sigstore %s is not supported. Configure a sigstore-staging: location.", url.Scheme, url.String())
+		return false, fmt.Errorf("Writing directly to a %s sigstore %s is not supported. Configure a sigstore-staging: location", url.Scheme, url.String())
 	default:
 		return false, fmt.Errorf("Unsupported scheme when deleting signature from %s", url.String())
 	}

docker/docker_image_src.go

@@ -246,7 +246,7 @@ func deleteImage(ctx *types.SystemContext, ref dockerReference) error {
 	switch get.StatusCode {
 	case http.StatusOK:
 	case http.StatusNotFound:
-		return fmt.Errorf("Unable to delete %v. Image may not exist or is not stored with a v2 Schema in a v2 registry.", ref.ref)
+		return fmt.Errorf("Unable to delete %v. Image may not exist or is not stored with a v2 Schema in a v2 registry", ref.ref)
 	default:
 		return fmt.Errorf("Failed to delete %v: %s (%v)", ref.ref, manifestBody, get.Status)
 	}

image/docker_schema1.go

@@ -204,7 +204,7 @@ func fixManifestLayers(manifest *manifestSchema1) error {
 		}
 	}
 	if imgs[len(imgs)-1].Parent != "" {
-		return errors.New("Invalid parent ID in the base layer of the image.")
+		return errors.New("Invalid parent ID in the base layer of the image")
 	}
 	// check general duplicates to error instead of a deadlock
 	idmap := make(map[string]struct{})
@@ -223,7 +223,7 @@ func fixManifestLayers(manifest *manifestSchema1) error {
 			manifest.FSLayers = append(manifest.FSLayers[:i], manifest.FSLayers[i+1:]...)
 			manifest.History = append(manifest.History[:i], manifest.History[i+1:]...)
 		} else if imgs[i].Parent != imgs[i+1].ID {
-			return fmt.Errorf("Invalid parent ID. Expected %v, got %v.", imgs[i+1].ID, imgs[i].Parent)
+			return fmt.Errorf("Invalid parent ID. Expected %v, got %v", imgs[i+1].ID, imgs[i].Parent)
 		}
 	}
 	return nil