Fix copy into workdir for a single file

When copying a single file to the workdir make sure to create the workdir
and not to overwrite it as file.

Fixes containers/podman#10671

Signed-off-by: Paul Holzinger <pholzing@redhat.com>

add.go

@@ -287,7 +287,7 @@ func (b *Builder) Add(destination string, extract bool, options AddAndCopyOption
 			destination = tmpDestination
 		}
 	}
-	destMustBeDirectory := (len(sources) > 1) || strings.HasSuffix(destination, string(os.PathSeparator))
+	destMustBeDirectory := (len(sources) > 1) || strings.HasSuffix(destination, string(os.PathSeparator)) || destination == b.WorkDir()
 	destCanBeFile := false
 	if len(sources) == 1 {
 		if len(remoteSources) == 1 {

tests/bud.bats

@@ -1830,6 +1830,20 @@ _EOF
   test -s "${root}"/subdir/file2.txt
 }
 
+# regression test for https://github.com/containers/podman/issues/10671
+@test "bud-copy-workdir --layers" {
+  _prefetch alpine
+
+  target=testimage
+  run_buildah bud --signature-policy ${TESTSDIR}/policy.json --layers -t ${target} -f Dockerfile.2 ${TESTSDIR}/bud/copy-workdir
+  run_buildah from ${target}
+  cid="$output"
+  run_buildah mount "${cid}"
+  root="$output"
+  test -d "${root}"/subdir
+  test -s "${root}"/subdir/file1.txt
+}
+
 @test "bud-build-arg-cache" {
   _prefetch busybox alpine
   target=derived-image

tests/bud/copy-workdir/Dockerfile.2

@@ -0,0 +1,4 @@
+FROM alpine
+WORKDIR /subdir
+COPY file1.txt /subdir
+RUN ls