app: harden mirroring lifecycle and state

1 files changed, 48 insertions, 0 deletions

diff --git a/app/src/main/java/invalid/lena/scrcpy/Licenses.java b/app/src/main/java/invalid/lena/scrcpy/Licenses.java
new file mode 100644
index 0000000..8e66912
--- /dev/null
+++ b/app/src/main/java/invalid/lena/scrcpy/Licenses.java
@@ -0,0 +1,48 @@
+package invalid.lena.scrcpy;
+
+import android.app.Activity;
+import android.os.Bundle;
+import android.view.WindowInsets;
+import android.widget.TextView;
+
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.nio.charset.StandardCharsets;
+
+// Shows the bundled third-party notices.
+//
+// This is a legal requirement, not a courtesy. The APK links
+// libspake2.so, which is LGPL-3.0: section 4 lets an LGPL library be
+// combined into a differently-licensed work only if the combined work
+// gives prominent notice that the library is used and is covered by the
+// LGPL, and points at the source needed to relink it. Shipping that text
+// as an asset no code reads is not notice. This screen is what makes it
+// notice.
+public final class Licenses extends Activity {
+
+    private static final String ASSET = "THIRD_PARTY_NOTICES";
+
+    @Override
+    protected void onCreate(Bundle saved) {
+        super.onCreate(saved);
+        setContentView(R.layout.licenses);
+        Ui.padForInsets(findViewById(R.id.root), WindowInsets.Type.systemBars());
+        ((TextView) findViewById(R.id.notices)).setText(read());
+    }
+
+    private String read() {
+        try (InputStream in = getAssets().open(ASSET)) {
+            ByteArrayOutputStream out = new ByteArrayOutputStream();
+            byte[] buf = new byte[8192];
+            for (int n; (n = in.read(buf)) >= 0; ) {
+                if (n == 0) throw new IOException("license asset read made no progress");
+                out.write(buf, 0, n);
+            }
+            return out.toString(StandardCharsets.UTF_8.name());
+        } catch (IOException e) {
+            Log.e(e, "licenses: cannot read %s", ASSET);
+            return getString(R.string.licenses_unavailable);
+        }
+    }
+}