Fix text input event segfault

The text input control_event was initially designed for mapping
SDL_TextInputEvent, limited to 32 characters.

For simplicity, the copy/paste feature was implemented using the same
control_event: it just sends the text to paste.

However, the pasted text might have a length breaking some assumptions:
 - on the client, the event max-size was smaller than the text
   max-length,
 - on the server, the raw buffer storing the events was smaller than the
   max event size.

Fix these inconsistencies, and encode the length on 2 bytes, to accept
more than 256 characters.

Fixes <https://github.com/Genymobile/scrcpy/issues/10>.

server/src/main/java/com/genymobile/scrcpy/ControlEventReader.java

@@ -13,8 +13,8 @@ public class ControlEventReader {
     private static final int SCROLL_PAYLOAD_LENGTH = 16;
     private static final int COMMAND_PAYLOAD_LENGTH = 1;
 
-    private static final int TEXT_MAX_LENGTH = 256;
-    private static final int RAW_BUFFER_SIZE = 128;
+    public static final int TEXT_MAX_LENGTH = 300;
+    private static final int RAW_BUFFER_SIZE = 1024;
 
     private final byte[] rawBuffer = new byte[RAW_BUFFER_SIZE];
     private final ByteBuffer buffer = ByteBuffer.wrap(rawBuffer);
@@ -94,7 +94,7 @@ public class ControlEventReader {
         if (buffer.remaining() < 1) {
             return null;
         }
-        int len = toUnsigned(buffer.get());
+        int len = toUnsigned(buffer.getShort());
         if (buffer.remaining() < len) {
             return null;
         }

server/src/test/java/com/genymobile/scrcpy/ControlEventReaderTest.java

@@ -3,14 +3,15 @@ package com.genymobile.scrcpy;
 import android.view.KeyEvent;
 import android.view.MotionEvent;
 
-import org.junit.Assert;
-import org.junit.Test;
-
 import java.io.ByteArrayInputStream;
 import java.io.ByteArrayOutputStream;
 import java.io.DataOutputStream;
 import java.io.IOException;
 import java.nio.charset.StandardCharsets;
+import java.util.Arrays;
+
+import org.junit.Assert;
+import org.junit.Test;
 
 public class ControlEventReaderTest {
 
@@ -43,8 +44,8 @@ public class ControlEventReaderTest {
         DataOutputStream dos = new DataOutputStream(bos);
         dos.writeByte(ControlEvent.TYPE_TEXT);
         byte[] text = "testé".getBytes(StandardCharsets.UTF_8);
-        dos.writeByte(text.length);
-        dos.write("testé".getBytes(StandardCharsets.UTF_8));
+        dos.writeShort(text.length);
+        dos.write(text);
         byte[] packet = bos.toByteArray();
 
         reader.readFrom(new ByteArrayInputStream(packet));
@@ -54,6 +55,26 @@ public class ControlEventReaderTest {
         Assert.assertEquals("testé", event.getText());
     }
 
+    @Test
+    public void testParseLongTextEvent() throws IOException {
+        ControlEventReader reader = new ControlEventReader();
+
+        ByteArrayOutputStream bos = new ByteArrayOutputStream();
+        DataOutputStream dos = new DataOutputStream(bos);
+        dos.writeByte(ControlEvent.TYPE_TEXT);
+        byte[] text = new byte[ControlEventReader.TEXT_MAX_LENGTH];
+        Arrays.fill(text, (byte) 'a');
+        dos.writeShort(text.length);
+        dos.write(text);
+        byte[] packet = bos.toByteArray();
+
+        reader.readFrom(new ByteArrayInputStream(packet));
+        ControlEvent event = reader.next();
+
+        Assert.assertEquals(ControlEvent.TYPE_TEXT, event.getType());
+        Assert.assertEquals(new String(text, StandardCharsets.US_ASCII), event.getText());
+    }
+
     @Test
     public void testParseMouseEvent() throws IOException {
         ControlEventReader reader = new ControlEventReader();