deleteFolder(): check if passed argument is a symlink

Prevents possible data loss when user replaced directory '~/storage' with
a symlink.

app/src/main/java/com/termux/app/TermuxInstaller.java

@@ -209,18 +209,18 @@ private static String determineTermuxArchName() {
  Arrays.toString(Build.SUPPORTED_ABIS));
  }
 
- /** Delete a folder and all its content or throw. */
+ /** Delete a folder and all its content or throw. Don't follow symlinks. */
  static void deleteFolder(File fileOrDirectory) throws IOException {
- File[] children = fileOrDirectory.listFiles();
- if (children != null) {
- for (File child : children) {
- if (child.getCanonicalFile().equals(child.getAbsoluteFile())) {
+ if (fileOrDirectory.getCanonicalPath().equals(fileOrDirectory.getAbsolutePath()) && fileOrDirectory.isDirectory()) {
+ File[] children = fileOrDirectory.listFiles();
+
+ if (children != null) {
+ for (File child : children) {
  deleteFolder(child);
- } else {
- child.delete();
  }
  }
  }
+
  if (!fileOrDirectory.delete()) {
  throw new RuntimeException("Unable to delete " + (fileOrDirectory.isDirectory() ? "directory " : "file ") + fileOrDirectory.getAbsolutePath());
  }