TerminalApp: Template for offline disk resize

1: Get root_partition from app's internal directory
2: Run e2fsck and resize2fs on root partition

This isn't enabled yet.

Bug: 371491254
Test: Resize partition (increase and shrink) and verify root partitions
gets mounted in VM after resize
Change-Id: Ic277513628b16979ab274fe007d8a620d3e4f84a
Signed-off-by: Akilesh Kailash <akailash@google.com>
diff --git a/android/TerminalApp/java/com/android/virtualization/terminal/MainActivity.java b/android/TerminalApp/java/com/android/virtualization/terminal/MainActivity.java
index c232e37..c3a9fa8 100644
--- a/android/TerminalApp/java/com/android/virtualization/terminal/MainActivity.java
+++ b/android/TerminalApp/java/com/android/virtualization/terminal/MainActivity.java
@@ -17,8 +17,11 @@
 
 import android.content.ClipData;
 import android.content.ClipboardManager;
+import android.content.Context;
 import android.content.Intent;
 import android.os.Bundle;
+import android.system.ErrnoException;
+import android.system.Os;
 import android.util.Log;
 import android.view.Menu;
 import android.view.MenuItem;
@@ -35,6 +38,12 @@
 
 import com.google.android.material.appbar.MaterialToolbar;
 
+import java.io.File;
+import java.io.FileDescriptor;
+import java.io.FileNotFoundException;
+import java.io.IOException;
+import java.io.RandomAccessFile;
+
 public class MainActivity extends AppCompatActivity
         implements VmLauncherServices.VmLauncherServiceCallback,
                 AccessibilityManager.TouchExplorationStateChangeListener {
@@ -45,6 +54,17 @@
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
+
+        try {
+            // No resize for now.
+            long newSizeInBytes = 0;
+            diskResize(this, newSizeInBytes);
+        } catch (IOException e) {
+            Log.e(TAG, "Failed to resize disk", e);
+            Toast.makeText(this, "Error resizing disk: " + e.getMessage(), Toast.LENGTH_LONG)
+                    .show();
+        }
+
         Toast.makeText(this, R.string.vm_creation_message, Toast.LENGTH_SHORT).show();
         VmLauncherServices.startVmLauncherService(this, this);
 
@@ -69,6 +89,90 @@
         getSystemService(AccessibilityManager.class).addTouchExplorationStateChangeListener(this);
     }
 
+    private void diskResize(Context context, long sizeInBytes) throws IOException {
+        try {
+            if (sizeInBytes == 0) {
+                return;
+            }
+            File file = getPartitionFile(context, "root_part");
+            String filePath = file.getAbsolutePath();
+            Log.d(TAG, "Disk-resize in progress for partition: " + filePath);
+
+            long currentSize = Os.stat(filePath).st_size;
+            runE2fsck(filePath);
+            if (sizeInBytes > currentSize) {
+                allocateSpace(file, sizeInBytes);
+            }
+
+            resizeFilesystem(filePath, sizeInBytes);
+        } catch (ErrnoException e) {
+            Log.e(TAG, "ErrnoException during disk resize", e);
+            throw new IOException("ErrnoException during disk resize", e);
+        } catch (IOException e) {
+            Log.e(TAG, "Failed to resize disk", e);
+            throw e;
+        }
+    }
+
+    private static File getPartitionFile(Context context, String fileName)
+            throws FileNotFoundException {
+        File file = new File(context.getFilesDir(), fileName);
+        if (!file.exists()) {
+            Log.d(TAG, fileName + " - file not found");
+            throw new FileNotFoundException("File not found: " + fileName);
+        }
+        return file;
+    }
+
+    private static void allocateSpace(File file, long sizeInBytes) throws IOException {
+        try {
+            RandomAccessFile raf = new RandomAccessFile(file, "rw");
+            FileDescriptor fd = raf.getFD();
+            Os.posix_fallocate(fd, 0, sizeInBytes);
+            raf.close();
+            Log.d(TAG, "Allocated space to: " + sizeInBytes + " bytes");
+        } catch (ErrnoException e) {
+            Log.e(TAG, "Failed to allocate space", e);
+            throw new IOException("Failed to allocate space", e);
+        }
+    }
+
+    private static void runE2fsck(String filePath) throws IOException {
+        try {
+            runCommand("/system/bin/e2fsck", "-f", filePath);
+            Log.d(TAG, "e2fsck completed: " + filePath);
+        } catch (IOException e) {
+            Log.e(TAG, "Failed to run e2fsck", e);
+            throw e;
+        }
+    }
+
+    private static void resizeFilesystem(String filePath, long sizeInBytes) throws IOException {
+        long sizeInMB = sizeInBytes / (1024 * 1024);
+        if (sizeInMB == 0) {
+            Log.e(TAG, "Invalid size: " + sizeInBytes + " bytes");
+            throw new IllegalArgumentException("Size cannot be zero MB");
+        }
+        String sizeArg = sizeInMB + "M";
+        try {
+            runCommand("/system/bin/resize2fs", filePath, sizeArg);
+            Log.d(TAG, "resize2fs completed: " + filePath + ", size: " + sizeArg);
+        } catch (IOException e) {
+            Log.e(TAG, "Failed to run resize2fs", e);
+            throw e;
+        }
+    }
+
+    private static void runCommand(String... command) throws IOException {
+        try {
+            Process process = new ProcessBuilder(command).redirectErrorStream(true).start();
+            process.waitFor();
+        } catch (InterruptedException e) {
+            Thread.currentThread().interrupt();
+            throw new IOException("Command interrupted", e);
+        }
+    }
+
     @Override
     protected void onDestroy() {
         getSystemService(AccessibilityManager.class).removeTouchExplorationStateChangeListener(this);