dropbox: make across config server side Move/Copy/DirMove fallback to copy

If we are doing a cross remote transfer then attempting a
Move/Copy/DirMove where we don't have permission gives
`from_lookup/not_found` errors.

This patch notices that error and only if we are doing a cross remote
transfer it engages the fallback where the file is streamed.

See: https://forum.rclone.org/t/dropbox-io-error-movedir-failed-from-lookup-not-found-when-try-to-move-copy-works/34088

backend/dropbox/dropbox.go

@@ -1078,6 +1078,15 @@ func (f *Fs) Copy(ctx context.Context, src fs.Object, remote string) (fs.Object,
 		return shouldRetry(ctx, err)
 	})
 	if err != nil {
+		switch e := err.(type) {
+		case files.CopyV2APIError:
+			// If we are doing a cross remote transfer then from_lookup/not_found indicates we
+			// don't have permission to read the source, so engage the slow path
+			if srcObj.fs != f && e.EndpointError != nil && e.EndpointError.FromLookup != nil && e.EndpointError.FromLookup.Tag == files.LookupErrorNotFound {
+				fs.Debugf(srcObj, "Copy failed attempting fallback: %v", err)
+				return nil, fs.ErrorCantCopy
+			}
+		}
 		return nil, fmt.Errorf("copy failed: %w", err)
 	}
 
@@ -1139,6 +1148,15 @@ func (f *Fs) Move(ctx context.Context, src fs.Object, remote string) (fs.Object,
 		return shouldRetry(ctx, err)
 	})
 	if err != nil {
+		switch e := err.(type) {
+		case files.MoveV2APIError:
+			// If we are doing a cross remote transfer then from_lookup/not_found indicates we
+			// don't have permission to read the source, so engage the slow path
+			if srcObj.fs != f && e.EndpointError != nil && e.EndpointError.FromLookup != nil && e.EndpointError.FromLookup.Tag == files.LookupErrorNotFound {
+				fs.Debugf(srcObj, "Move failed attempting fallback: %v", err)
+				return nil, fs.ErrorCantMove
+			}
+		}
 		return nil, fmt.Errorf("move failed: %w", err)
 	}
 
@@ -1257,6 +1275,15 @@ func (f *Fs) DirMove(ctx context.Context, src fs.Fs, srcRemote, dstRemote string
 		return shouldRetry(ctx, err)
 	})
 	if err != nil {
+		switch e := err.(type) {
+		case files.MoveV2APIError:
+			// If we are doing a cross remote transfer then from_lookup/not_found indicates we
+			// don't have permission to read the source, so engage the slow path
+			if srcFs != f && e.EndpointError != nil && e.EndpointError.FromLookup != nil && e.EndpointError.FromLookup.Tag == files.LookupErrorNotFound {
+				fs.Debugf(srcFs, "DirMove failed attempting fallback: %v", err)
+				return fs.ErrorCantDirMove
+			}
+		}
 		return fmt.Errorf("MoveDir failed: %w", err)
 	}
 

backend/webdav/webdav.go

@@ -991,6 +991,7 @@ func (f *Fs) copyOrMove(ctx context.Context, src fs.Object, remote string, metho
 		}
 		return nil, fs.ErrorCantMove
 	}
+	srcFs := srcObj.fs
 	dstPath := f.filePath(remote)
 	err := f.mkParentDir(ctx, dstPath)
 	if err != nil {
@@ -1013,9 +1014,10 @@ func (f *Fs) copyOrMove(ctx context.Context, src fs.Object, remote string, metho
 	if f.useOCMtime {
 		opts.ExtraHeaders["X-OC-Mtime"] = fmt.Sprintf("%d", src.ModTime(ctx).Unix())
 	}
-	err = f.pacer.Call(func() (bool, error) {
-		resp, err = f.srv.Call(ctx, &opts)
-		return f.shouldRetry(ctx, resp, err)
+	// Direct the MOVE/COPY to the source server
+	err = srcFs.pacer.Call(func() (bool, error) {
+		resp, err = srcFs.srv.Call(ctx, &opts)
+		return srcFs.shouldRetry(ctx, resp, err)
 	})
 	if err != nil {
 		return nil, fmt.Errorf("Copy call failed: %w", err)
@@ -1109,9 +1111,10 @@ func (f *Fs) DirMove(ctx context.Context, src fs.Fs, srcRemote, dstRemote string
 			"Overwrite":   "F",
 		},
 	}
-	err = f.pacer.Call(func() (bool, error) {
-		resp, err = f.srv.Call(ctx, &opts)
-		return f.shouldRetry(ctx, resp, err)
+	// Direct the MOVE/COPY to the source server
+	err = srcFs.pacer.Call(func() (bool, error) {
+		resp, err = srcFs.srv.Call(ctx, &opts)
+		return srcFs.shouldRetry(ctx, resp, err)
 	})
 	if err != nil {
 		return fmt.Errorf("DirMove MOVE call failed: %w", err)