add getRootfsFile

instead of constant for filename in several places

Bug: 366386783
Test: build
Change-Id: Iba59fe79c6c5841e8be66460c97204cac1c6e6c5
diff --git a/android/TerminalApp/java/com/android/virtualization/terminal/MainActivity.java b/android/TerminalApp/java/com/android/virtualization/terminal/MainActivity.java
index 10451ec..2f0d301 100644
--- a/android/TerminalApp/java/com/android/virtualization/terminal/MainActivity.java
+++ b/android/TerminalApp/java/com/android/virtualization/terminal/MainActivity.java
@@ -289,16 +289,6 @@
         }
     }
 
-    public static File getPartitionFile(Context context, String fileName)
-            throws FileNotFoundException {
-        File file = new File(InstallUtils.getInternalStorageDir(context), fileName);
-        if (!file.exists()) {
-            Log.d(TAG, file.getAbsolutePath() + " - 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");
@@ -536,7 +526,7 @@
 
     private void resizeDiskIfNecessary() {
         try {
-            File file = getPartitionFile(this, "root_part");
+            File file = InstallUtils.getRootfsFile(this);
             SharedPreferences sharedPref = this.getSharedPreferences(
                     getString(R.string.preference_file_key), Context.MODE_PRIVATE);
             SharedPreferences.Editor editor = sharedPref.edit();
diff --git a/android/TerminalApp/java/com/android/virtualization/terminal/SettingsDiskResizeActivity.kt b/android/TerminalApp/java/com/android/virtualization/terminal/SettingsDiskResizeActivity.kt
index 58be98d..7ccce9c 100644
--- a/android/TerminalApp/java/com/android/virtualization/terminal/SettingsDiskResizeActivity.kt
+++ b/android/TerminalApp/java/com/android/virtualization/terminal/SettingsDiskResizeActivity.kt
@@ -27,6 +27,7 @@
 import android.widget.TextView
 import androidx.appcompat.app.AppCompatActivity
 import androidx.core.view.isVisible
+import com.android.virtualization.vmlauncher.InstallUtils
 import com.google.android.material.button.MaterialButton
 import com.google.android.material.slider.Slider
 import java.util.regex.Pattern
@@ -55,7 +56,7 @@
                     0
                 )
             ).toFloat();
-        val partition = MainActivity.getPartitionFile(this, "root_part")
+        val partition = InstallUtils.getRootfsFile(this)
         val minDiskSizeMb =
             bytesToMb(MainActivity.getMinFilesystemSize(partition)).toFloat()
                 .coerceAtMost(diskSizeMb)
diff --git a/libs/vm_launcher_lib/java/com/android/virtualization/vmlauncher/InstallUtils.java b/libs/vm_launcher_lib/java/com/android/virtualization/vmlauncher/InstallUtils.java
index 57691bf..d55d268 100644
--- a/libs/vm_launcher_lib/java/com/android/virtualization/vmlauncher/InstallUtils.java
+++ b/libs/vm_launcher_lib/java/com/android/virtualization/vmlauncher/InstallUtils.java
@@ -28,6 +28,7 @@
 
 import java.io.BufferedInputStream;
 import java.io.File;
+import java.io.FileNotFoundException;
 import java.io.IOException;
 import java.nio.file.Files;
 import java.nio.file.Path;
@@ -41,6 +42,7 @@
 
     private static final String VM_CONFIG_FILENAME = "vm_config.json";
     private static final String COMPRESSED_PAYLOAD_FILENAME = "images.tar.gz";
+    private static final String ROOTFS_FILENAME = "root_part";
     private static final String INSTALLATION_COMPLETED_FILENAME = "completed";
     private static final String PAYLOAD_DIR = "linux";
 
@@ -172,4 +174,13 @@
             return false;
         }
     }
+
+    public static File getRootfsFile(Context context) throws FileNotFoundException {
+        File file = new File(getInternalStorageDir(context), ROOTFS_FILENAME);
+        if (!file.exists()) {
+            Log.d(TAG, file.getAbsolutePath() + " - file not found");
+            throw new FileNotFoundException("File not found: " + ROOTFS_FILENAME);
+        }
+        return file;
+    }
 }