proxy: Change the imgid to uint64

In PR review for a different issue, the question of what happens
if we hit overflow for the imageid serial was hit.  This feels
pretty unlikely; if I did the math right, it'd require opening
an average of 136 images per second to overflow it in a year.
Nevertheless, in practice what we're sending on the wire is just a JSON
number, and if we extend this to the "max safe JSON number" of 2^53,
it'd take 285,616,414 images per second to overflow in a year, going
from implausible to probably impossible.

With a bit more work of course, we could make this a sparse mapping
and reuse freed numbers, but eh.

Signed-off-by: Colin Walters <walters@verbum.org>

cmd/skopeo/proxy.go

@@ -154,7 +154,7 @@ type activePipe struct {
 // openImage is an opened image reference
 type openImage struct {
 	// id is an opaque integer handle
-	id        uint32
+	id        uint64
 	src       types.ImageSource
 	cachedimg types.Image
 }
@@ -169,9 +169,9 @@ type proxyHandler struct {
 	cache  types.BlobInfoCache
 
 	// imageSerial is a counter for open images
-	imageSerial uint32
+	imageSerial uint64
 	// images holds our opened images
-	images map[uint32]*openImage
+	images map[uint64]*openImage
 	// activePipes maps from "pipeid" to a pipe + goroutine pair
 	activePipes map[uint32]*activePipe
 }
@@ -307,14 +307,6 @@ func (h *proxyHandler) CloseImage(args []any) (replyBuf, error) {
 	return ret, nil
 }
 
-func parseImageID(v any) (uint32, error) {
-	imgidf, ok := v.(float64)
-	if !ok {
-		return 0, fmt.Errorf("expecting integer imageid, not %T", v)
-	}
-	return uint32(imgidf), nil
-}
-
 // parseUint64 validates that a number fits inside a JavaScript safe integer
 func parseUint64(v any) (uint64, error) {
 	f, ok := v.(float64)
@@ -328,7 +320,7 @@ func parseUint64(v any) (uint64, error) {
 }
 
 func (h *proxyHandler) parseImageFromID(v any) (*openImage, error) {
-	imgid, err := parseImageID(v)
+	imgid, err := parseUint64(v)
 	if err != nil {
 		return nil, err
 	}
@@ -828,7 +820,7 @@ func (h *proxyHandler) processRequest(readBytes []byte) (rb replyBuf, terminate
 func (opts *proxyOptions) run(args []string, stdout io.Writer) error {
 	handler := &proxyHandler{
 		opts:        opts,
-		images:      make(map[uint32]*openImage),
+		images:      make(map[uint64]*openImage),
 		activePipes: make(map[uint32]*activePipe),
 	}
 	defer handler.close()

integration/proxy_test.go

@@ -239,7 +239,7 @@ func runTestGetManifestAndConfig(p *proxy, img string) error {
 	if !ok {
 		return fmt.Errorf("OpenImage return value is %T", v)
 	}
-	imgid := uint32(imgidv)
+	imgid := uint64(imgidv)
 	if imgid == 0 {
 		return fmt.Errorf("got zero from expected image")
 	}
@@ -254,7 +254,7 @@ func runTestGetManifestAndConfig(p *proxy, img string) error {
 	if !ok {
 		return fmt.Errorf("OpenImageOptional return value is %T", v)
 	}
-	imgid2 := uint32(imgidv)
+	imgid2 := uint64(imgidv)
 	if imgid2 == 0 {
 		return fmt.Errorf("got zero from expected image")
 	}
@@ -325,7 +325,7 @@ func runTestOpenImageOptionalNotFound(p *proxy, img string) error {
 	if !ok {
 		return fmt.Errorf("OpenImageOptional return value is %T", v)
 	}
-	imgid := uint32(imgidv)
+	imgid := uint64(imgidv)
 	if imgid != 0 {
 		return fmt.Errorf("Unexpected optional image id %v", imgid)
 	}