rework device interface, remove libgpiod, add command device

README.md

@@ -7,7 +7,13 @@ Configuration is done using environment variables.
   - `ram`: Sessions are stored in RAM.
 - `WOLBODGE_DEVICE_TYPE`: Device type to pick, defaults to `test`.
   - `test`: A dummy device, used for testing.
-  - `libgpiod`: Uses the libgpiod commands under the hood. The gpio chip is specified using `WOLBODGE_DEVICE_GPIOCHIP`, the power button pin using `WOLBODGE_DEVICE_POWER_BUTTON_PIN` and the power LED pin using `WOLBODGE_DEVICE_POWER_LED_PIN`.
+  - `command`: Runs a subprocess to aquire the info. See the example below for more info.
+
+### Example: Raspberry pi using the command device
+- `WOLBODGE_DEVICE_TYPE=command`
+- `WOLBODGE_DEVICE_SHELL=bash -c $COMMAND`: Configure which shell we should use.
+- `WOLBODGE_DEVICE_STATUS_COMMAND=gpioget --bias pull-down gpiochip0 17 > $WOLBODGE_STATUS_FILE`: Which command should be used to aquire the device's status. It should echo out a "0" for off and a "1" for on into the file created at "$WOLBODGE_STATUS_FILE".
+- `WOLBODGE_DEVICE_TOGGLE_STATUS_COMMAND=gpioset gpiochip0 27=1 && sleep 2 && gpioset gpiochip0 27=0`: Which command should be used to toggle the device's status. This usually involves pressing the power button virtually.
 
 ## Usage example
 Usage example for a backup script that backs up to a NAS that isn't online 24/7.
@@ -39,4 +45,3 @@ fi
 
 ## TODOs
 - Alerts when a session has existed for a long time
-- Command device that can use commands to turn on/off a device

devices/command.go

@@ -0,0 +1,94 @@
+package devices
+
+import (
+	"fmt"
+	"os"
+	"os/exec"
+	"strings"
+	"sync"
+)
+
+// TODO: A command device
+// You will be able to use shell commands to push the power button and get the status.
+//
+// Status will give an env variable: WOLBODGE_STATUS_FILE, you will be expected to write a "0" or a "1" there, depending on the state.
+
+func NewCommand(shell []string, statusCmd string, toggleStatusCmd string) Device {
+	device := &command{
+		shell:           shell,
+		statusCmd:       statusCmd,
+		toggleStatusCmd: toggleStatusCmd,
+		lock:            sync.Mutex{},
+	}
+	return device
+}
+
+type command struct {
+	shell           []string
+	statusCmd       string
+	toggleStatusCmd string
+	lock            sync.Mutex
+}
+
+func (d *command) Status() (bool, error) {
+	d.lock.Lock()
+	defer d.lock.Unlock()
+
+	file, err := os.CreateTemp("", "wolbodge-status-*")
+	if err != nil {
+		return false, fmt.Errorf("failed to create temporary status file: %w", err)
+	}
+	defer os.Remove(file.Name())
+
+	cmd := d.makeCommand(d.statusCmd)
+	cmd.Env = append(
+		cmd.Environ(),
+		fmt.Sprintf("WOLBODGE_STATUS_FILE=%s", file.Name()),
+	)
+
+	err = cmd.Run()
+	if err != nil {
+		return false, fmt.Errorf("failed to run command: %w", err)
+	}
+
+	data, err := os.ReadFile(file.Name())
+	if err != nil {
+		return false, fmt.Errorf("failed to read status file: %w", err)
+	}
+
+	content := string(data)
+	content = strings.TrimSpace(content)
+
+	switch content {
+	case "0":
+		return false, nil
+	case "1":
+		return true, nil
+	default:
+		return false, fmt.Errorf("invalid status file content, expected \"0\" or \"1\", got \"%s\"", content)
+	}
+}
+
+func (d *command) ToggleStatus() error {
+	d.lock.Lock()
+	defer d.lock.Unlock()
+
+	cmd := d.makeCommand(d.toggleStatusCmd)
+	err := cmd.Run()
+	if err != nil {
+		return fmt.Errorf("failed to run command: %w", err)
+	}
+
+	return nil
+}
+
+func (d *command) makeCommand(command string) *exec.Cmd {
+	args := make([]string, len(d.shell))
+	copy(args, d.shell)
+
+	for i := range args {
+		args[i] = strings.ReplaceAll(args[i], "$COMMAND", command)
+	}
+
+	return exec.Command(args[0], args[1:]...)
+}

devices/devices.go

@@ -6,8 +6,13 @@ import (
 )
 
 type Device interface {
+	// Retreive the status of the device.
+	// This is usually acheived by taking a reading from the power LED.
 	Status() (bool, error)
-	PushPowerButton() error
+
+	// Toggle the status of the device.
+	// This is usually achieved by pressing the power button.
+	ToggleStatus() error
 }
 
 func KeepDeviceInSync(logger *log.Logger, device Device, wantStatus func() (bool, error), exit <-chan bool) {
@@ -36,15 +41,15 @@ func KeepDeviceInSync(logger *log.Logger, device Device, wantStatus func() (bool
 				continue
 			}
 
-			err = device.PushPowerButton()
+			err = device.ToggleStatus()
 			if err != nil {
-				logger.Printf("Failed to push power button, waiting 2 minutes until next attempt: %s", err)
+				logger.Printf("Failed to toggle device status, waiting 2 minutes until next attempt: %s", err)
 				// Cooldown to not overwhelm the device with start/stop requests
 				time.Sleep(2 * time.Minute)
 				return
 			}
 
-			logger.Printf("Pushed power button")
+			logger.Printf("Toggled device status")
 			time.Sleep(2 * time.Minute)
 		}
 	}

devices/libgpiod.go

@@ -1,101 +0,0 @@
-package devices
-
-import (
-	"fmt"
-	"os/exec"
-	"sync"
-	"time"
-)
-
-// TODO: Do not use subprocesses here, they are unreliable, provide hidden dependencies and are a common target for vulnerabilities.
-// TODO: Improve pulldown, pullup
-func NewLibgpiod(gpiochip string, powerButtonPin int, powerLEDPin int) Device {
-	device := &libgpiod{
-		gpiochip:       gpiochip,
-		powerButtonPin: powerButtonPin,
-		powerLEDPin:    powerLEDPin,
-		lock:           sync.Mutex{},
-	}
-
-	return device
-}
-
-type libgpiod struct {
-	gpiochip       string
-	powerButtonPin int
-	powerLEDPin    int
-	lock           sync.Mutex
-}
-
-func (d *libgpiod) Status() (bool, error) {
-	d.lock.Lock()
-	defer d.lock.Unlock()
-
-	status, err := d.read(d.powerLEDPin)
-	if err != nil {
-		return false, err
-	}
-
-	return status, nil
-}
-
-func (d *libgpiod) PushPowerButton() error {
-	d.lock.Lock()
-	defer d.lock.Unlock()
-
-	err := d.write(d.powerButtonPin, 1)
-	if err != nil {
-		return err
-	}
-
-	time.Sleep(2 * time.Second)
-
-	err = d.write(d.powerButtonPin, 0)
-	if err != nil {
-		return err
-	}
-
-	return nil
-}
-
-func (d *libgpiod) write(pin int, value int) error {
-	cmd := exec.Command(
-		"env", "sh", "-c",
-		fmt.Sprintf("gpioset %s %d=%d", d.gpiochip, pin, value),
-	)
-
-	outRaw, err := cmd.Output()
-	if err != nil {
-		return err
-	}
-
-	out := string(outRaw)
-	if out == "" {
-		return nil
-	}
-
-	return fmt.Errorf("unexpected command output: %s", err)
-}
-
-func (d *libgpiod) read(pin int) (bool, error) {
-	cmd := exec.Command(
-		"env", "sh", "-c",
-		fmt.Sprintf("gpioget --bias pull-down %s %d", d.gpiochip, pin),
-	)
-
-	outRaw, err := cmd.Output()
-	if err != nil {
-		return false, err
-	}
-
-	out := string(outRaw)
-
-	switch out {
-	case "0\n":
-		return false, nil
-	case "1\n":
-		return true, nil
-	default:
-		return false, fmt.Errorf("unexpected command output: %s", out)
-	}
-}

devices/test.go

@@ -2,10 +2,10 @@ package devices
 
 import "sync"
 
-func NewTest(initialStatus bool) Device {
+func NewTest(status bool) Device {
 	device := &test{
 		lock:   sync.Mutex{},
-		status: initialStatus,
+		status: status,
 	}
 	return device
 }
@@ -22,7 +22,7 @@ func (d *test) Status() (bool, error) {
 	return d.status, nil
 }
 
-func (d *test) PushPowerButton() error {
+func (d *test) ToggleStatus() error {
 	d.lock.Lock()
 	defer d.lock.Unlock()
 

env.go

@@ -5,6 +5,7 @@ import (
 	"log"
 	"os"
 	"strconv"
+	"strings"
 
 	"git.1e99.eu/1e99/wolbodge/devices"
 	"git.1e99.eu/1e99/wolbodge/sessions"
@@ -31,15 +32,15 @@ func NewDevice() (devices.Device, error) {
 	case "test":
 		return devices.NewTest(false), nil
 
-	case "libgpiod":
+	case "command":
-		var gpiochip string
+		var shell []string
-		var powerButtonPin int
+		var statusCmd string
-		var powerLEDPin int
+		var toggleStatusCmd string
-		Env("WOLBODGE_DEVICE_GPIOCHIP", &gpiochip, "gpiochip0")
+		Env("WOLBODGE_DEVICE_SHELL", &shell, "")
-		Env("WOLBODGE_DEVICE_POWER_BUTTON_PIN", &powerButtonPin, "27")
+		Env("WOLBODGE_DEVICE_STATUS_COMMAND", &statusCmd, "")
-		Env("WOLBODGE_DEVICE_POWER_LED_PIN", &powerLEDPin, "17")
+		Env("WOLBODGE_DEVICE_TOGGLE_STATUS_COMMAND", &toggleStatusCmd, "")
 
-		return devices.NewLibgpiod(gpiochip, powerButtonPin, powerLEDPin), nil
+		return devices.NewCommand(shell, statusCmd, toggleStatusCmd), nil
 
 	default:
 		return nil, fmt.Errorf("unknown device type: %s", deviceType)
@@ -73,5 +74,8 @@ func Env(name string, out any, def string) {
 
 	case *string:
 		*value = raw
+
+	case *[]string:
+		*value = strings.Fields(raw)
 	}
 }