Android java.io.IOException: write failed: EBADF (Bad file number)

Question

I have read several posts about the EBADF error that does not resolve my issue. What makes my case unique is that I am trying to write to the getFilesDir, that should be writable by the application.

I am getting the EBADF error when executing the encrypt method. The file argument is created using:

new File(mContext.getFilesDir(), "file.dat")

Where is a listing of the encrypt method:

public static void encrypt(File file, String password, List<Object> objects) {

    byte[] salt = generateSalt();
    byte[] iv = generateIV();
    Cipher c = createCipher(password, salt, Cipher.ENCRYPT_MODE, iv);

    try (FileOutputStream fos = new FileOutputStream(file)) {
        fos.write(salt);
        fos.write(iv);
        try (CipherOutputStream cos = new CipherOutputStream(fos, c);
        ObjectOutputStream oos = new ObjectOutputStream(cos)) {
            for (Object o : objects) {
                oos.writeObject(o);
            }
        }

    } catch (FileNotFoundException e) {
        throw new RuntimeException(e);
    } catch (IOException e) {
        throw new RuntimeException(e);
    }
}

Can anyone see why I am getting the exception?

Here is the exception log:

 Caused by: java.lang.RuntimeException: java.io.IOException: write failed: EBADF (Bad file number)
    at za.co.lot24media.password.util.EncryptUtil.encrypt(EncryptUtil.java:69)
    at za.co.lot24media.password.store.Store.save(Store.java:94)
    at za.co.lot24media.password.store.Store.createSamples(Store.java:179)
    at za.co.lot24media.password.store.Store.load(Store.java:76)
    at za.co.lot24media.password.activity.login.LoginAction$2.doInBackground(LoginAction.java:62)
    at za.co.lot24media.password.activity.login.LoginAction$2.doInBackground(LoginAction.java:55)
    at android.os.AsyncTask$2.call(AsyncTask.java:292)
    at java.util.concurrent.FutureTask.run(FutureTask.java:237)
    at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231) 
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112) 
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587) 
    at java.lang.Thread.run(Thread.java:818) 
 Caused by: java.io.IOException: write failed: EBADF (Bad file number)
    at libcore.io.IoBridge.write(IoBridge.java:502)
    at java.io.FileOutputStream.write(FileOutputStream.java:186)
    at java.io.OutputStream.write(OutputStream.java:82)
    at javax.crypto.CipherOutputStream.close(CipherOutputStream.java:129)
    at za.co.lot24media.password.util.EncryptUtil.encrypt(EncryptUtil.java:64)

** EDITED **

The issue seems to be with the ObjectOutputStream writing to the CipherOutputStream. When I remove the ObjectOutputStream from the encrypt() method, the method succeeds. The code below works:

    public static void encrypt(File file, String password, StoreDataRecord storeDataRecord) {

    byte[] salt = generateSalt();
    byte[] iv = generateIV();
    Cipher c = createCipher(password, salt, Cipher.ENCRYPT_MODE, iv);

    try (FileOutputStream fos = new FileOutputStream(file)) {
        fos.write(salt);
        fos.write(iv);

        try (CipherOutputStream cos = new CipherOutputStream(fos, c)) {
            cos.write(new byte[10]);
        }

    } catch (FileNotFoundException e) {
        throw new RuntimeException(e);
    } catch (IOException e) {
        throw new RuntimeException(e);
    }
}

I used byte[10] just to write arbitrary data to the stream.

** EDIT 2 **

The following solution also works, writing the data to a ByteArrayOutputStream first:

public static void encrypt(File file, String password, StoreDataRecord storeDataRecord) {

    byte[] salt = generateSalt();
    byte[] iv = generateIV();
    Cipher c = createCipher(password, salt, Cipher.ENCRYPT_MODE, iv);

    try (FileOutputStream fos = new FileOutputStream(file)) {
        fos.write(salt);
        fos.write(iv);

        try (ByteArrayOutputStream bos = new ByteArrayOutputStream();
             ObjectOutputStream oos = new ObjectOutputStream(bos);
             CipherOutputStream cos = new CipherOutputStream(fos, c)) {
            oos.writeObject(storeDataRecord.getVersion());
            oos.writeObject(storeDataRecord.getItems());
            cos.write(bos.toByteArray());
        }
    } catch (FileNotFoundException e) {
        throw new RuntimeException(e);
    } catch (IOException e) {
        throw new RuntimeException(e);
    }
}

Answer 1

As i see your encrypt method call on doInBackground so it can produce some complicated situation like move to another fragment or create two instance of fragment and this make android confuse. Best way is you ignore encrypt method when onDestroy() called.

And make sure your streams not closed before you use them.

Hope it's helps