infer_clone/infer/tests/codetoanalyze/java/lab/LeaksExceptions.java

/*
 * Copyright (c) 2017-present, Facebook, Inc.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 */

package codetoanalyze.java.checkers;

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;

public class LeaksExceptions {

  void tryWithResourcesOk() throws IOException, FileNotFoundException {
    // this is syntactic sugar that makes sure stream gets closed
    try (FileInputStream stream = new FileInputStream("file.txt")) {
      // do something with stream here
    }
  }

  void closeInFinallyOk() throws IOException, FileNotFoundException {
    FileInputStream stream = null;
    try {
      stream = new FileInputStream("file.txt");
    } finally {
      if (stream != null) {
        stream.close();
      }
    }
  }

  void twoResourcesBad() throws IOException, FileNotFoundException {
    FileInputStream stream1 = null;
    FileInputStream stream2 = null;
    try {
      stream1 = new FileInputStream("file1.txt");
      stream2 = new FileInputStream("file2.txt");
    } finally {
      if (stream1 != null) {
        stream1.close(); // close() can throw!
      }
      if (stream2 != null) {
        stream2.close(); // then this is never reached and stream2 leaks
      }
    }
  }

  void leakInCatchBad() throws IOException, FileNotFoundException {
    FileInputStream stream = null;
    try {
      stream = new FileInputStream("file_in.txt");
    } catch (Exception e) {
      FileOutputStream fis = new FileOutputStream("file_out.txt");
      // forgot to close fis
    } finally {
      if (stream != null) {
        stream.close();
      }
    }
  }
}