podman-remote,bindings: trim context path correctly when its emptydir

pkg/bindings/images/build.go

@@ -647,23 +647,27 @@ func nTar(excludes []string, sources ...string) (io.ReadCloser, error) {
 					return err
 				}
 
+				separator := string(filepath.Separator)
 				// check if what we are given is an empty dir, if so then continue w/ it. Else return.
 				// if we are given a file or a symlink, we do not want to exclude it.
-				if d.IsDir() && s == path {
-					var p *os.File
-					p, err = os.Open(path)
-					if err != nil {
-						return err
-					}
-					defer p.Close()
-					_, err = p.Readdir(1)
-					if err != io.EOF {
-						return nil // non empty root dir, need to return
-					} else if err != nil {
-						logrus.Errorf("While reading directory %v: %v", path, err)
+				if s == path {
+					separator = ""
+					if d.IsDir() {
+						var p *os.File
+						p, err = os.Open(path)
+						if err != nil {
+							return err
+						}
+						defer p.Close()
+						_, err = p.Readdir(1)
+						if err != io.EOF {
+							return nil // non empty root dir, need to return
+						} else if err != nil {
+							logrus.Errorf("While reading directory %v: %v", path, err)
+						}
 					}
 				}
-				name := filepath.ToSlash(strings.TrimPrefix(path, s+string(filepath.Separator)))
+				name := filepath.ToSlash(strings.TrimPrefix(path, s+separator))
 
 				excluded, err := pm.Matches(name) //nolint:staticcheck
 				if err != nil {

test/e2e/build_test.go

@@ -386,6 +386,41 @@ RUN exit 5`, ALPINE)
 		Expect(data).To(ContainSubstring(buildah.Version))
 	})
 
+	It("podman-remote send correct path to copier", func() {
+		if IsRemote() {
+			podmanTest.StopRemoteService()
+			podmanTest.StartRemoteService()
+		} else {
+			Skip("Only valid at remote test, case works fine for regular podman and buildah")
+		}
+		cwd, err := os.Getwd()
+		Expect(err).ToNot(HaveOccurred())
+
+		// Write target and fake files
+		targetSubPath := filepath.Join(cwd, "emptydir")
+		if _, err = os.Stat(targetSubPath); err != nil {
+			if os.IsNotExist(err) {
+				err = os.Mkdir(targetSubPath, 0755)
+				Expect(err).ToNot(HaveOccurred())
+			}
+		}
+
+		containerfile := fmt.Sprintf(`FROM %s
+COPY /* /dir`, ALPINE)
+
+		containerfilePath := filepath.Join(cwd, "ContainerfilePathToCopier")
+		err = os.WriteFile(containerfilePath, []byte(containerfile), 0644)
+		Expect(err).ToNot(HaveOccurred())
+
+		session := podmanTest.Podman([]string{"build", "--pull-never", "-t", "test", "-f", "ContainerfilePathToCopier", targetSubPath})
+		session.WaitWithDefaultTimeout()
+		// NOTE: Docker and buildah both should error when `COPY /* /dir` is done on emptydir
+		// as context. However buildkit simply ignores this so when buildah also starts ignoring
+		// for such case edit this test to return 0 and check that no `/dir` should be in the result.
+		Expect(session).Should(Exit(125))
+		Expect(session.ErrorToString()).To(ContainSubstring("can't make relative to"))
+	})
+
 	It("podman remote test container/docker file is not inside context dir", func() {
 		// Given
 		// Switch to temp dir and restore it afterwards