React to lid open via acpi_listen

Author: sstark

acpi_listen.go

@@ -0,0 +1,46 @@
+package main
+
+import (
+	"bufio"
+	"os/exec"
+)
+
+// AcpiEvent returns a channel from which you can receive ACPI events
+// by reading from acpi_listen output.
+// Arguments are like printed by acpi_listen, for example:
+//
+//	"button/lid LID close"
+//	"button/lid LID open"
+//	"video/brightnessdown BRTDN 00000087 00000000"
+//	"wmi PNP0C14:05 000000d0 00000000"
+//
+// Passing one or more of these strings will make the returned channel
+// only react to the corresponding events. Passing "" will make it react
+// to all events.
+// The item returned from the channel will be the ACPI event string in
+// the same format as the filter argument.
+// AcpiEvent will create a goroutine that spawns an acpi_listen instance
+// and wait for output from it to fill the event channel.
+func AcpiEvent(cmdName string, watchedEvent string) (eventsOut chan string, err error) {
+	eventsOut = make(chan string, 100)
+	cmd := exec.Command(cmdName)
+	out, err := cmd.StdoutPipe()
+	if err != nil {
+		return nil, err
+	}
+	scanner := bufio.NewScanner(out)
+	err = cmd.Start()
+	if err != nil {
+		return nil, err
+	}
+	go func() {
+		for scanner.Scan() {
+			text := scanner.Text()
+			if text == watchedEvent || watchedEvent == "" {
+				line := scanner.Text()
+				eventsOut <- line
+			}
+		}
+	}()
+	return eventsOut, err
+}

acpi_listen_test.go

@@ -0,0 +1,16 @@
+package main
+
+import (
+	"testing"
+)
+
+const mockAcpiListen = "./mock_acpi_listen.sh"
+
+func TestAcpiEvent(t *testing.T) {
+	acpiChan, _ := AcpiEvent(mockAcpiListen, acpiLidOpenEvent)
+	event := <-acpiChan
+
+	if event != acpiLidOpenEvent {
+		t.Errorf("got %q, want %q", event, acpiLidOpenEvent)
+	}
+}

clock.go

@@ -7,6 +7,11 @@ import (
 	"time"
 )
 
+const (
+	acpiLidOpenEvent = "button/lid LID open"
+	acpiListenCmd    = "acpi_listen"
+)
+
 // repeatUntilInterrupt runs the given function every interval.
 // It will return whenever one of the signals in interruptSignals is received.
 func repeatUntilInterrupt(callback func(), interval time.Duration, interruptSignals ...os.Signal) {
@@ -16,10 +21,17 @@ func repeatUntilInterrupt(callback func(), interval time.Duration, interruptSign
 	sigc := make(chan os.Signal, 1)
 	signal.Notify(sigc, interruptSignals...)
 	quit := make(chan bool)
+	acpiEvent, acpiErr := AcpiEvent(acpiListenCmd, acpiLidOpenEvent)
+	if acpiErr != nil {
+		slog.Warn("ACPI event listener could not be started", "error", acpiErr)
+	}
 	for {
 		select {
 		case <-ticker.C:
 			callback()
+		case <-acpiEvent:
+			slog.Info("acpi event received")
+			callback()
 		case sig := <-sigc:
 			slog.Debug("received signal", "signal", sig)
 			go func() { quit <- true }()

main_test.go

@@ -2,17 +2,15 @@ package main
 
 import (
 	"flag"
-	"io"
-	"log/slog"
 	"strconv"
 	"strings"
 	"testing"
 	"time"
 )
 
-func TestMain(t *testing.T) {
-	slog.SetDefault(slog.New(slog.NewTextHandler(io.Discard, nil)))
-}
+//func TestMain(t *testing.T) {
+//	slog.SetDefault(slog.New(slog.NewTextHandler(io.Discard, nil)))
+//}
 
 type roundFloatTestCase struct {
 	in        float64

mock_acpi_listen.sh

@@ -0,0 +1,24 @@
+#!/bin/bash
+
+output=(
+"video/brightnessdown BRTDN 00000087 00000000"
+"video/brightnessup BRTUP 00000086 00000000"
+"video/brightnessdown BRTDN 00000087 00000000"
+"video/brightnessup BRTUP 00000086 00000000"
+"button/lid LID close"
+"button/lid LID open"
+"video/brightnessdown BRTDN 00000087 00000000"
+"wmi PNP0C14:05 000000d0 00000000"
+"video/brightnessup BRTUP 00000086 00000000"
+"wmi PNP0C14:05 000000d0 00000000"
+"video/brightnessdown BRTDN 00000087 00000000"
+"wmi PNP0C14:05 000000d0 00000000"
+)
+
+for line in "${output[@]}"
+do
+  sleep 0.1
+  echo "$line"
+done
+
+sleep 10000000000000