usb: add api for reading from device stream

Author: Netdex

app/src/main/assets/scripts/debug.lua

@@ -0,0 +1,6 @@
+kb = luausb.create({ id = 0, type = "keyboard" })
+
+while true do
+    print(kb.debug())
+    wait(1000)
+end

app/src/main/assets/scripts/exfiltrate.lua

@@ -15,8 +15,8 @@ while true do
     end
 
     print("running")
-    -- wait 1 second for things to settle down
-    wait(1000)
+    -- wait 2 second for things to settle down
+    wait(2000)
 
     kb.chord(MOD_LSUPER, KEY_R)
     wait(1000)

app/src/main/java/org/netdex/androidusbscript/function/DeviceStream.java

@@ -4,13 +4,16 @@
 
 import java.io.Closeable;
 import java.io.IOException;
+import java.io.InputStream;
 import java.io.OutputStream;
+import java.io.PushbackInputStream;
 
 public abstract class DeviceStream implements Closeable {
     private final FileSystem fs_;
     private final String devicePath_;
 
     private OutputStream os_;
+    private InputStream is_;
 
     public DeviceStream(FileSystem fs, String devicePath) {
         this.fs_ = fs;
@@ -22,6 +25,14 @@ protected void write(byte[] b) throws IOException {
         this.getOutputStream().write(b);
     }
 
+    protected int read(byte[] b) throws IOException {
+//        Log.d(TAG, String.format("read %s > %s", Util.bytesToHex(buffer), devicePath_));
+        return this.getInputStream().read(b);
+    }
+    public int available() throws IOException {
+        return this.getInputStream().available();
+    }
+
     protected OutputStream getOutputStream() throws IOException {
         if (os_ == null) {
             if (!fs_.exists(devicePath_))
@@ -31,9 +42,20 @@ protected OutputStream getOutputStream() throws IOException {
         return os_;
     }
 
+    protected InputStream getInputStream() throws IOException {
+        if (is_ == null) {
+            if (!fs_.exists(devicePath_))
+                throw new RuntimeException(String.format("Device \"%s\" does not exist", devicePath_));
+            is_ = fs_.fopen_r(devicePath_);
+        }
+        return is_;
+    }
+
     @Override
     public void close() throws IOException {
         if (os_ != null)
             os_.close();
+        if (is_ != null)
+            is_.close();
     }
 }

app/src/main/java/org/netdex/androidusbscript/task/LuaUsbLibrary.java

@@ -243,7 +243,7 @@ public keyboard(int id) {
             public LuaValue call() {
                 LuaValue library = tableOf();
                 for (LuaFunction f : new LuaFunction[]{
-                        new raw(), new chord(), new press(), new string()}) {
+                        new raw(), new chord(), new press(), new string(), new debug()}) {
                     library.set(f.name(), f);
                 }
                 return library;
@@ -314,7 +314,6 @@ public Varargs invoke(Varargs args) {
             }
 
             class string extends TwoArgFunction {
-
                 @Override
                 public LuaValue call(LuaValue arg1, LuaValue arg2) {
                     String string = arg1.checkjstring();
@@ -327,6 +326,17 @@ public LuaValue call(LuaValue arg1, LuaValue arg2) {
                     return NIL;
                 }
             }
+
+            class debug extends ZeroArgFunction {
+                @Override
+                public LuaValue call() {
+                    try {
+                        return valueOf(hid_.available());
+                    } catch (IOException e) {
+                        throw new LuaError(e);
+                    }
+                }
+            }
         }
 
         class mouse extends ZeroArgFunction {