cp: do not allow dir->file copying

Fix a bug in `podman-cp` to forbid copying directories to files.
Previously, the directory was copied to the parent directory of the file
which is wrong.

Signed-off-by: Valentin Rothberg <rothberg@redhat.com>

cmd/podman/containers/cp.go

@@ -177,6 +177,10 @@ func copyFromContainer(container string, containerPath string, hostPath string)
 		containerTarget = filepath.Dir(containerTarget)
 	}
 
+	if !isStdout && containerInfo.IsDir && !hostInfo.IsDir {
+		return errors.New("destination must be a directory when copying a directory")
+	}
+
 	reader, writer := io.Pipe()
 	hostCopy := func() error {
 		defer reader.Close()
@@ -334,6 +338,10 @@ func copyToContainer(container string, containerPath string, hostPath string) er
 		stdinFile = tmpFile.Name()
 	}
 
+	if hostInfo.IsDir && !containerInfo.IsDir {
+		return errors.New("destination must be a directory when copying a directory")
+	}
+
 	reader, writer := io.Pipe()
 	hostCopy := func() error {
 		defer writer.Close()

test/system/065-cp.bats

@@ -272,6 +272,11 @@ load helpers
         run_podman rm -f cpcontainer
     done < <(parse_table "$tests")
 
+    run_podman create --name cpcontainer --workdir=/srv $cpimage sleep infinity
+    run_podman 125 cp $srcdir cpcontainer:/etc/os-release
+    is "$output" "Error: destination must be a directory when copying a directory" "cannot copy directory to file"
+    run_podman rm -f cpcontainer
+
     run_podman rmi -f $cpimage
 }
 
@@ -343,6 +348,10 @@ load helpers
         is "$(< $destdir$dest_fullname/containerfile1)" "${randomcontent[1]}" "$description"
         rm -rf $destdir/*
     done < <(parse_table "$tests")
+
+    touch $destdir/testfile
+    run_podman 125 cp cpcontainer:/etc/ $destdir/testfile
+    is "$output" "Error: destination must be a directory when copying a directory" "cannot copy directory to file"
     run_podman rm -f cpcontainer
 
     run_podman rmi -f $cpimage