Question

I have a function that copies binary file

    public static void copyFile(String Src, String Dst) throws FileNotFoundException, IOException {
    File f1 = new File(Src);
    File f2 = new File(Dst);
    FileInputStream in = new FileInputStream(f1);

    FileOutputStream out = new FileOutputStream(f2);

    byte[] buf = new byte[1024];
    int len;
    while ((len = in.read(buf)) > 0) {
        out.write(buf, 0, len);
    }
    in.close();
    out.close();
}

and the second function

    private String copyDriverToSafeLocation(String driverPath) {
    String safeDir = System.getProperty("user.home");
    String safeLocation = safeDir + "\\my_pkcs11tmp.dll";
    try {
        Utils.copyFile(driverPath, safeLocation);
        return safeLocation;
    } catch (Exception ex) {
        System.out.println("Exception occured while copying driver: " + ex);
        return null;
    }
}

The second function is run for every driver found in the system.
The driver file is copied and I am trying to initialize PKCS11 with that driver.
If initialization failed I go to next driver, I copy it to the tmp location and so on.

The initialization is in try/catch block
After the first failure I am no longer able to copy next driver to the standard location.

I get the exception

Exception occured while copying driver: java.io.FileNotFoundException: C:\Users\Norbert\my_pkcs11tmp.dll (The process cannot access the file because it is being used by another process)

How can I avoid the exception and safely copy the driver file?

For those curious why am I trying to copy the driver … PKCS11 has nasty BUG, which prevents using drivers stored in the location that has “(” in the path … and this is a case I am facing.

I will appreciate your help.

Answer 1

If the file is used by an other process and locked, there is no generic solutions to be able to access it. You best chance is to use FileLock but it’s plateform-dependant, read the documentation, it’s written that the results are “advisory”, so be carefull. you can also take a look at the ReentrantReadWriteLock class.