llb: fix relative working directory in client

Signed-off-by: Tonis Tiigi <tonistiigi@gmail.com>

client/client_test.go

@@ -33,6 +33,7 @@ import (
 
 func TestClientIntegration(t *testing.T) {
 	integration.Run(t, []integration.Test{
+		testRelativeWorkDir,
 		testCallDiskUsage,
 		testBuildMultiMount,
 		testBuildHTTPSource,
@@ -51,6 +52,37 @@ func TestClientIntegration(t *testing.T) {
 	})
 }
 
+func testRelativeWorkDir(t *testing.T, sb integration.Sandbox) {
+	t.Parallel()
+	requiresLinux(t)
+	c, err := New(sb.Address())
+	require.NoError(t, err)
+	defer c.Close()
+
+	pwd := llb.Image("docker.io/library/busybox:latest").
+		Dir("test1").
+		Dir("test2").
+		Run(llb.Shlex(`sh -c "pwd > /out/pwd"`)).
+		AddMount("/out", llb.Scratch())
+
+	def, err := pwd.Marshal()
+	require.NoError(t, err)
+
+	destDir, err := ioutil.TempDir("", "buildkit")
+	require.NoError(t, err)
+	defer os.RemoveAll(destDir)
+
+	_, err = c.Solve(context.TODO(), def, SolveOpt{
+		Exporter:          ExporterLocal,
+		ExporterOutputDir: destDir,
+	}, nil)
+	require.NoError(t, err)
+
+	dt, err := ioutil.ReadFile(filepath.Join(destDir, "pwd"))
+	require.NoError(t, err)
+	require.Equal(t, []byte("/test1/test2\n"), dt)
+}
+
 func testCallDiskUsage(t *testing.T, sb integration.Sandbox) {
 	t.Parallel()
 	c, err := New(sb.Address())

client/llb/meta.go

@@ -2,6 +2,7 @@ package llb
 
 import (
 	"fmt"
+	"path"
 
 	"github.com/google/shlex"
 )
@@ -31,7 +32,15 @@ func dir(str string) StateOption {
 
 func dirf(str string, v ...interface{}) StateOption {
 	return func(s State) State {
-		return s.WithValue(keyDir, fmt.Sprintf(str, v...))
+		value := fmt.Sprintf(str, v...)
+		if !path.IsAbs(value) {
+			prev := getDir(s)
+			if prev == "" {
+				prev = "/"
+			}
+			value = path.Join(prev, value)
+		}
+		return s.WithValue(keyDir, value)
 	}
 }
 

client/llb/meta_test.go

@@ -0,0 +1,24 @@
+package llb
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestRelativeWd(t *testing.T) {
+	st := Scratch().Dir("foo")
+	require.Equal(t, st.GetDir(), "/foo")
+
+	st = st.Dir("bar")
+	require.Equal(t, st.GetDir(), "/foo/bar")
+
+	st = st.Dir("..")
+	require.Equal(t, st.GetDir(), "/foo")
+
+	st = st.Dir("/baz")
+	require.Equal(t, st.GetDir(), "/baz")
+
+	st = st.Dir("../../..")
+	require.Equal(t, st.GetDir(), "/")
+}