oci: Allow environment values to be empty

An empty string for an environment variable simply means that the
variable is unset. Do not error out if the env value is empty.

Fixes kata-containers#288

Signed-off-by: Archana Shinde <archana.m.shinde@intel.com>

cli/exec_test.go

@@ -560,16 +560,20 @@ func TestExecuteWithValidProcessJson(t *testing.T) {
 	assert.Equal(exitErr.ExitCode(), 0, "Exit code should have been 0 for fake workload %s", workload)
 }
 
-func TestExecuteWithInvalidEnvironment(t *testing.T) {
+func TestExecuteWithEmptyEnvironmentValue(t *testing.T) {
 	assert := assert.New(t)
 
 	tmpdir, err := ioutil.TempDir("", "")
 	assert.NoError(err)
 	defer os.RemoveAll(tmpdir)
 
+	pidFilePath := filepath.Join(tmpdir, "pid")
+	consolePath := "/dev/ptmx"
+
+	flagSet := testExecParamsSetup(t, pidFilePath, consolePath, false)
+
 	processPath := filepath.Join(tmpdir, "process.json")
 
-	flagSet := flag.NewFlagSet("", 0)
 	flagSet.String("process", processPath, "")
 	flagSet.Parse([]string{testContainerID})
 	ctx := cli.NewContext(cli.NewApp(), flagSet, nil)
@@ -600,9 +604,24 @@ func TestExecuteWithInvalidEnvironment(t *testing.T) {
 	}()
 
 	processJSON := `{
+				"consoleSize": {
+					"height": 15,
+					"width": 15
+				},
+				"terminal": true,
+				"user": {
+					"uid": 0,
+					"gid": 0
+				},
+				"args": [
+					"sh"
+				],
 				"env": [
+					"PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin",
 					"TERM="
-				]
+				],
+				"cwd": "/"
+
 			}`
 
 	f, err := os.OpenFile(processPath, os.O_RDWR|os.O_CREATE, testFileMode)
@@ -614,13 +633,33 @@ func TestExecuteWithInvalidEnvironment(t *testing.T) {
 
 	defer os.Remove(processPath)
 
+	workload := []string{"cat", "/dev/null"}
+
+	testingImpl.EnterContainerFunc = func(sandboxID, containerID string, cmd vc.Cmd) (vc.VCSandbox, vc.VCContainer, *vc.Process, error) {
+		// create a fake container process
+		command := exec.Command(workload[0], workload[1:]...)
+		err := command.Start()
+		assert.NoError(err, "Unable to start process %v: %s", workload, err)
+
+		vcProcess := vc.Process{}
+		vcProcess.Pid = command.Process.Pid
+
+		return &vcmock.Sandbox{}, &vcmock.Container{}, &vcProcess, nil
+	}
+
+	defer func() {
+		testingImpl.EnterContainerFunc = nil
+		os.Remove(pidFilePath)
+	}()
+
 	fn, ok := execCLICommand.Action.(func(context *cli.Context) error)
 	assert.True(ok)
 
 	// vcAnnotations.EnvVars error due to incorrect environment
 	err = fn(ctx)
-	assert.Error(err)
-	assert.False(vcmock.IsMockError(err))
+	exitErr, ok := err.(*cli.ExitError)
+	assert.True(ok, true, "Exit code not received for fake workload process")
+	assert.Equal(exitErr.ExitCode(), 0, "Exit code should have been 0 for empty environment variable value")
 }
 
 func TestGenerateExecParams(t *testing.T) {

virtcontainers/pkg/oci/utils.go

@@ -640,10 +640,6 @@ func EnvVars(envs []string) ([]vc.EnvVar, error) {
 
 		envSlice[1] = strings.Trim(envSlice[1], "' ")
 
-		if envSlice[1] == "" {
-			return []vc.EnvVar{}, fmt.Errorf("Environment value cannot be empty")
-		}
-
 		envVar := vc.EnvVar{
 			Var:   envSlice[0],
 			Value: envSlice[1],

virtcontainers/pkg/oci/utils_test.go

@@ -479,12 +479,6 @@ func TestMalformedEnvVars(t *testing.T) {
 		t.Fatalf("EnvVars() succeeded unexpectedly: [%s] variable=%s value=%s", envVars[0], r[0].Var, r[0].Value)
 	}
 
-	envVars = []string{"TERM="}
-	r, err = EnvVars(envVars)
-	if err == nil {
-		t.Fatalf("EnvVars() succeeded unexpectedly: [%s] variable=%s value=%s", envVars[0], r[0].Var, r[0].Value)
-	}
-
 	envVars = []string{"=foo"}
 	r, err = EnvVars(envVars)
 	if err == nil {