evdev: enable marshaling and unmarshaling from outside, docs improvem…

…ents
function61 · Apr 3, 2022 · 80c4607 · 80c4607
1 parent 5e89d4b
commit 80c4607
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Showing 2 changed files with 21 additions and 7 deletions.
diff --git a/app/evdev/evdev.go b/app/evdev/evdev.go
@@ -104,11 +104,14 @@ func (d *Device) SetLedOff(led Led) error {
 }
 
 func (d *Device) writeEvent(evType EventType, code uint16, value int32) error {
-	return binary.Write(d.handle, binary.LittleEndian, &InputEvent{
+	event := &InputEvent{
+		// TODO: we're sending time as zero?
 		Type:  evType,
 		Code:  code,
 		Value: value,
-	})
+	}
+	_, err := d.handle.Write(event.AsBytes())
+	return err
 }
 
 func readOneInputEvent(inputDevice *os.File) (*InputEvent, error) {
@@ -121,7 +124,7 @@ func readOneInputEvent(inputDevice *os.File) (*InputEvent, error) {
 	if n <= 0 {
 		return nil, nil
 	}
-	return eventFromBuffer(buffer)
+	return InputEventFromBytes(buffer)
 }
 
 func grabExclusiveInputDeviceAccess(inputDevice *os.File) error {
@@ -133,7 +136,7 @@ func grabExclusiveInputDeviceAccess(inputDevice *os.File) error {
 	return nil
 }
 
-func eventFromBuffer(buffer []byte) (*InputEvent, error) {
+func InputEventFromBytes(buffer []byte) (*InputEvent, error) {
 	event := &InputEvent{}
 	err := binary.Read(bytes.NewBuffer(buffer), binary.LittleEndian, event)
 	return event, err

diff --git a/app/evdev/input_event.go b/app/evdev/input_event.go
@@ -1,6 +1,8 @@
 package evdev
 
 import (
+	"bytes"
+	"encoding/binary"
 	"fmt"
 	"syscall"
 	"time"
@@ -20,9 +22,9 @@ var eventsize = int(unsafe.Sizeof(InputEvent{}))
 // Has to match the C struct/wire protocol
 type InputEvent struct {
 	Time  syscall.Timeval
-	Type  EventType
-	Code  uint16
-	Value int32
+	Type  EventType // EvKey | EvSyn | EvLed | ...
+	Code  uint16    // Code is the actual key code, e.g. KeyLEFTSHIFT
+	Value int32     // additional specifier like Press/Hold/Release when Type=EvKey
 }
 
 func (i *InputEvent) TimevalToTime() time.Time {
@@ -70,3 +72,12 @@ func (i *InputEvent) String() string {
 		return fmt.Sprintf("unknown: %d", i.Type)
 	}
 }
+
+// marshals to evdev "wire format"
+func (i *InputEvent) AsBytes() []byte {
+	buf := bytes.NewBuffer(make([]byte, 0, 24)) // 24 = sizeof(InputEvent)
+	if err := binary.Write(buf, binary.LittleEndian, i); err != nil {
+		panic(err)
+	}
+	return buf.Bytes()
+}