@@ -54,6 +54,7 @@ func GetHTTPErrorStatusCode(err error) int {

 			code    int

 		}{

 			{"not found", http.StatusNotFound},

+			{"cannot find", http.StatusNotFound},

 			{"no such", http.StatusNotFound},

 			{"bad parameter", http.StatusBadRequest},

 			{"no command", http.StatusBadRequest},

@@ -165,18 +165,25 @@ func (d *Daemon) ContainerExecStart(ctx context.Context, name string, stdin io.R

 		return fmt.Errorf("Error: Exec command %s is already running", ec.ID)

 	}

 	ec.Running = true

+	ec.Unlock()

+

+	c := d.containers.Get(ec.ContainerID)

+	logrus.Debugf("starting exec command %s in container %s", ec.ID, c.ID)

+	d.LogContainerEvent(c, "exec_start: "+ec.Entrypoint+" "+strings.Join(ec.Args, " "))

+

 	defer func() {

 		if err != nil {

+			ec.Lock()

 			ec.Running = false

 			exitCode := 126

 			ec.ExitCode = &exitCode

+			if err := ec.CloseStreams(); err != nil {

+				logrus.Errorf("failed to cleanup exec %s streams: %s", c.ID, err)

+			}

+			ec.Unlock()

+			c.ExecCommands.Delete(ec.ID)

 		}

 	}()

-	ec.Unlock()

-

-	c := d.containers.Get(ec.ContainerID)

-	logrus.Debugf("starting exec command %s in container %s", ec.ID, c.ID)

-	d.LogContainerEvent(c, "exec_start: "+ec.Entrypoint+" "+strings.Join(ec.Args, " "))

 	if ec.OpenStdin && stdin != nil {

 		r, w := io.Pipe()

@@ -90,7 +90,7 @@ func (daemon *Daemon) StateChanged(id string, e libcontainerd.StateInfo) error {

 			execConfig.Running = false

 			execConfig.StreamConfig.Wait()

 			if err := execConfig.CloseStreams(); err != nil {

-				logrus.Errorf("%s: %s", c.ID, err)

+				logrus.Errorf("failed to cleanup exec %s streams: %s", c.ID, err)

 			}

 			// remove the exec command from the container's store only and not the

@@ -120,21 +120,7 @@ func (s *DockerSuite) TestExecAPIStartMultipleTimesError(c *check.C) {

 	runSleepingContainer(c, "-d", "--name", "test")

 	execID := createExec(c, "test")

 	startExec(c, execID, http.StatusOK)

-

-	timeout := time.After(60 * time.Second)

-	var execJSON struct{ Running bool }

-	for {

-		select {

-		case <-timeout:

-			c.Fatal("timeout waiting for exec to start")

-		default:

-		}

-

-		inspectExec(c, execID, &execJSON)

-		if !execJSON.Running {

-			break

-		}

-	}

+	waitForExec(c, execID)

 	startExec(c, execID, http.StatusConflict)

 }

@@ -169,8 +155,43 @@ func (s *DockerSuite) TestExecAPIStartWithDetach(c *check.C) {

 	}

 }

+// #30311

+func (s *DockerSuite) TestExecAPIStartValidCommand(c *check.C) {

+	name := "exec_test"

+	dockerCmd(c, "run", "-d", "-t", "--name", name, "busybox", "/bin/sh")

+

+	id := createExecCmd(c, name, "true")

+	startExec(c, id, http.StatusOK)

+

+	waitForExec(c, id)

+

+	var inspectJSON struct{ ExecIDs []string }

+	inspectContainer(c, name, &inspectJSON)

+

+	c.Assert(inspectJSON.ExecIDs, checker.IsNil)

+}

+

+// #30311

+func (s *DockerSuite) TestExecAPIStartInvalidCommand(c *check.C) {

+	name := "exec_test"

+	dockerCmd(c, "run", "-d", "-t", "--name", name, "busybox", "/bin/sh")

+

+	id := createExecCmd(c, name, "invalid")

+	startExec(c, id, http.StatusNotFound)

+	waitForExec(c, id)

+

+	var inspectJSON struct{ ExecIDs []string }

+	inspectContainer(c, name, &inspectJSON)

+

+	c.Assert(inspectJSON.ExecIDs, checker.IsNil)

+}

+

 func createExec(c *check.C, name string) string {

-	_, b, err := request.SockRequest("POST", fmt.Sprintf("/containers/%s/exec", name), map[string]interface{}{"Cmd": []string{"true"}}, daemonHost())

+	return createExecCmd(c, name, "true")

+}

+

+func createExecCmd(c *check.C, name string, cmd string) string {

+	_, b, err := request.SockRequest("POST", fmt.Sprintf("/containers/%s/exec", name), map[string]interface{}{"Cmd": []string{cmd}}, daemonHost())

 	c.Assert(err, checker.IsNil, check.Commentf(string(b)))

 	createResp := struct {

@@ -198,3 +219,29 @@ func inspectExec(c *check.C, id string, out interface{}) {

 	err = json.NewDecoder(body).Decode(out)

 	c.Assert(err, checker.IsNil)

 }

+

+func waitForExec(c *check.C, id string) {

+	timeout := time.After(60 * time.Second)

+	var execJSON struct{ Running bool }

+	for {

+		select {

+		case <-timeout:

+			c.Fatal("timeout waiting for exec to start")

+		default:

+		}

+

+		inspectExec(c, id, &execJSON)

+		if !execJSON.Running {

+			break

+		}

+	}

+}

+

+func inspectContainer(c *check.C, id string, out interface{}) {

+	resp, body, err := request.SockRequestRaw("GET", fmt.Sprintf("/containers/%s/json", id), nil, "", daemonHost())

+	c.Assert(err, checker.IsNil)

+	defer body.Close()

+	c.Assert(resp.StatusCode, checker.Equals, http.StatusOK)

+	err = json.NewDecoder(body).Decode(out)

+	c.Assert(err, checker.IsNil)

+}