Update App version to 0.0.2

internal/usbgadget/changeset.go

@@ -34,6 +34,7 @@ const (
 	FileStateFileWrite // update file content without checking
 	FileStateMounted
 	FileStateMountedConfigFS
+	FileStateMountedFunctionFS
 	FileStateSymlink
 	FileStateSymlinkInOrderConfigFS // configfs is a shithole, so we need to check if the symlinks are created in the correct order
 	FileStateSymlinkNotInOrderConfigFS
@@ -52,6 +53,7 @@ var FileStateString = map[FileState]string{
 	FileStateSymlink:                "SYMLINK",
 	FileStateSymlinkInOrderConfigFS: "SYMLINK_IN_ORDER_CONFIGFS",
 	FileStateTouch:                  "TOUCH",
+	FileStateMountedFunctionFS:      "FUNCTIONFS_MOUNTED",
 }
 
 const (
@@ -78,6 +80,7 @@ const (
 	FileChangeResolvedActionRemoveDirectory
 	FileChangeResolvedActionTouch
 	FileChangeResolvedActionMountConfigFS
+	FileChangeResolvedActionMountFunctionFS
 )
 
 var FileChangeResolvedActionString = map[FileChangeResolvedAction]string{
@@ -96,6 +99,7 @@ var FileChangeResolvedActionString = map[FileChangeResolvedAction]string{
 	FileChangeResolvedActionRemoveDirectory:            "DIR_REMOVE",
 	FileChangeResolvedActionTouch:                      "TOUCH",
 	FileChangeResolvedActionMountConfigFS:              "CONFIGFS_MOUNT",
+	FileChangeResolvedActionMountFunctionFS:            "FUNCTIONFS_MOUNT",
 }
 
 type ChangeSet struct {
@@ -147,6 +151,8 @@ func (f *RequestedFileChange) String() string {
 		s = fmt.Sprintf("write: %s with content [%s]", f.Path, f.ExpectedContent)
 	case FileStateMountedConfigFS:
 		s = fmt.Sprintf("configfs: %s", f.Path)
+	case FileStateMountedFunctionFS:
+		s = fmt.Sprintf("functionfs: %s", f.Path)
 	case FileStateTouch:
 		s = fmt.Sprintf("touch: %s", f.Path)
 	case FileStateUnknown:
@@ -298,6 +304,8 @@ func (fc *FileChange) getFileChangeResolvedAction() FileChangeResolvedAction {
 		return FileChangeResolvedActionWriteFile
 	case FileStateTouch:
 		return FileChangeResolvedActionTouch
+	case FileStateMountedFunctionFS:
+		return FileChangeResolvedActionMountFunctionFS
 	}
 
 	// get the actual state of the file
@@ -424,6 +432,8 @@ func (c *ChangeSet) applyChange(change *FileChange) error {
 		return os.Chtimes(change.Path, time.Now(), time.Now())
 	case FileChangeResolvedActionMountConfigFS:
 		return mountConfigFS(change.Path)
+	case FileChangeResolvedActionMountFunctionFS:
+		return mountFunctionFS(change.Path)
 	case FileChangeResolvedActionDoNothing:
 		return nil
 	default:

internal/usbgadget/changeset_resolver.go

@@ -2,6 +2,7 @@ package usbgadget
 
 import (
 	"fmt"
+	"time"
 
 	"github.com/rs/zerolog"
 	"github.com/sourcegraph/tf-dag/dag"
@@ -127,6 +128,11 @@ func (c *ChangeSetResolver) applyChanges() error {
 		l.Str("action", actionStr).Str("change", change.String()).Msg("applying change")
 
 		err := c.changeset.applyChange(change)
+		if err != nil {
+			time.Sleep(500 * time.Millisecond)
+			err = c.changeset.applyChange(change)
+		}
+
 		if err != nil {
 			if change.IgnoreErrors {
 				c.l.Warn().Str("change", change.String()).Err(err).Msg("ignoring error")

internal/usbgadget/config.go

@@ -1,8 +1,11 @@
 package usbgadget
 
 import (
+	"bufio"
 	"fmt"
+	"os"
 	"os/exec"
+	"strings"
 )
 
 type gadgetConfigItem struct {
@@ -51,6 +54,8 @@ var defaultGadgetConfig = map[string]gadgetConfigItem{
 			"configuration": "Config 1: HID",
 		},
 	},
+	// mtp
+	"mtp": mtpConfig,
 	// keyboard HID
 	"keyboard": keyboardConfig,
 	// mouse HID
@@ -91,6 +96,8 @@ func (u *UsbGadget) isGadgetConfigItemEnabled(itemKey string) bool {
 		return u.enabledDevices.MassStorage
 	case "mass_storage_lun0":
 		return u.enabledDevices.MassStorage
+	case "mtp":
+		return u.enabledDevices.Mtp
 	case "audio":
 		return u.enabledDevices.Audio
 	default:
@@ -184,6 +191,45 @@ func mountConfigFS(path string) error {
 	return nil
 }
 
+func mountFunctionFS(path string) error {
+	err := os.MkdirAll("/dev/ffs-mtp", 0755)
+	if err != nil {
+		return fmt.Errorf("failed to create mtp dev dir: %w", err)
+	}
+	mounted := false
+	if f, err := os.Open("/proc/mounts"); err == nil {
+		scanner := bufio.NewScanner(f)
+		for scanner.Scan() {
+			if strings.Contains(scanner.Text(), functionFSPath) {
+				mounted = true
+				break
+			}
+		}
+		f.Close()
+	}
+
+	if !mounted {
+		err := exec.Command("mount", "-t", "functionfs", "mtp", path).Run()
+		if err != nil {
+			return fmt.Errorf("failed to mount functionfs: %w", err)
+		}
+	}
+
+	umtprdRunning := false
+	if out, err := exec.Command("pgrep", "-x", "umtprd").Output(); err == nil && len(out) > 0 {
+		umtprdRunning = true
+	}
+
+	if !umtprdRunning {
+		cmd := exec.Command("umtprd")
+		if err := cmd.Start(); err != nil {
+			return fmt.Errorf("failed to exec binary: %w", err)
+		}
+	}
+
+	return nil
+}
+
 func (u *UsbGadget) Init() error {
 	u.configLock.Lock()
 	defer u.configLock.Unlock()

internal/usbgadget/config_tx.go

@@ -131,6 +131,16 @@ func (tx *UsbGadgetTransaction) MountConfigFS() {
 	})
 }
 
+func (tx *UsbGadgetTransaction) MountFunctionFS() {
+	tx.addFileChange("mtp", RequestedFileChange{
+		Path:          functionFSPath,
+		Key:           "mtp",
+		ExpectedState: FileStateMountedFunctionFS,
+		Description:   "mount functionfs",
+		DependsOn:     []string{"reorder-symlinks"},
+	})
+}
+
 func (tx *UsbGadgetTransaction) CreateConfigPath() {
 	tx.mkdirAll(
 		"gadget",
@@ -164,7 +174,12 @@ func (tx *UsbGadgetTransaction) WriteGadgetConfig() {
 		deps = tx.writeGadgetItemConfig(item, deps)
 	}
 
-	tx.WriteUDC()
+	if tx.isGadgetConfigItemEnabled("mtp") {
+		tx.MountFunctionFS()
+		tx.WriteUDC(true)
+	} else {
+		tx.WriteUDC(false)
+	}
 }
 
 func (tx *UsbGadgetTransaction) getDisableKeys() []string {
@@ -315,17 +330,28 @@ func (tx *UsbGadgetTransaction) addReorderSymlinkChange(path string, target stri
 	})
 }
 
-func (tx *UsbGadgetTransaction) WriteUDC() {
+func (tx *UsbGadgetTransaction) WriteUDC(mtpServer bool) {
 	// bound the gadget to a UDC (USB Device Controller)
 	path := path.Join(tx.kvmGadgetPath, "UDC")
-	tx.addFileChange("udc", RequestedFileChange{
-		Key:             "udc",
-		Path:            path,
-		ExpectedState:   FileStateFileContentMatch,
-		ExpectedContent: []byte(tx.udc),
-		DependsOn:       []string{"reorder-symlinks"},
-		Description:     "write UDC",
-	})
+	if mtpServer {
+		tx.addFileChange("udc", RequestedFileChange{
+			Key:             "udc",
+			Path:            path,
+			ExpectedState:   FileStateFileContentMatch,
+			ExpectedContent: []byte(tx.udc),
+			DependsOn:       []string{"mtp"},
+			Description:     "write UDC",
+		})
+	} else {
+		tx.addFileChange("udc", RequestedFileChange{
+			Key:             "udc",
+			Path:            path,
+			ExpectedState:   FileStateFileContentMatch,
+			ExpectedContent: []byte(tx.udc),
+			DependsOn:       []string{"reorder-symlinks"},
+			Description:     "write UDC",
+		})
+	}
 }
 
 func (tx *UsbGadgetTransaction) RebindUsb(ignoreUnbindError bool) {

internal/usbgadget/consts.go

@@ -1,3 +1,4 @@
 package usbgadget
 
 const dwc3Path = "/sys/bus/platform/drivers/dwc3"
+const udcPath = "/sys/kernel/config/usb_gadget/kvm/UDC"

internal/usbgadget/mass_storage.go

@@ -23,3 +23,10 @@ var massStorageLun0Config = gadgetConfigItem{
 		"inquiry_string": "KVM  Virtual Media",
 	},
 }
+
+var mtpConfig = gadgetConfigItem{
+	order:      3003,
+	device:     "ffs.mtp",
+	path:       []string{"functions", "ffs.mtp"},
+	configPath: []string{"ffs.mtp"},
+}

internal/usbgadget/udc.go

@@ -80,7 +80,7 @@ func (u *UsbGadget) IsUDCBound() (bool, error) {
 
 // BindUDC binds the gadget to the UDC.
 func (u *UsbGadget) BindUDC() error {
-	err := os.WriteFile(path.Join(dwc3Path, "bind"), []byte(u.udc), 0644)
+	err := os.WriteFile(path.Join(udcPath, "bind"), []byte(u.udc), 0644)
 	if err != nil {
 		return fmt.Errorf("error binding UDC: %w", err)
 	}
@@ -89,7 +89,7 @@ func (u *UsbGadget) BindUDC() error {
 
 // UnbindUDC unbinds the gadget from the UDC.
 func (u *UsbGadget) UnbindUDC() error {
-	err := os.WriteFile(path.Join(dwc3Path, "unbind"), []byte(u.udc), 0644)
+	err := os.WriteFile(path.Join(udcPath, " "), []byte(u.udc), 0644)
 	if err != nil {
 		return fmt.Errorf("error unbinding UDC: %w", err)
 	}

internal/usbgadget/usbgadget.go

@@ -20,6 +20,7 @@ type Devices struct {
 	RelativeMouse bool `json:"relative_mouse"`
 	Keyboard      bool `json:"keyboard"`
 	MassStorage   bool `json:"mass_storage"`
+	Mtp           bool `json:"mtp"`
 	Audio         bool `json:"audio"`
 }
 
@@ -88,6 +89,9 @@ type UsbGadget struct {
 const configFSPath = "/sys/kernel/config"
 const gadgetPath = "/sys/kernel/config/usb_gadget"
 
+const functionFSPath = "/dev/ffs-mtp"
+const umtprdPath = "/usr/sbin/umtprd"
+
 var defaultLogger = logging.GetSubsystemLogger("usbgadget")
 
 // NewUsbGadget creates a new UsbGadget.