Class OSFileSystem

lib/org/apache/harmony/luni/platform/OSFileSystem.java:29–299

This is the portable implementation of the file system interface.

 * 
 */
class OSFileSystem implements IFileSystem {

    static {
        oneTimeInitializationImpl();
    }

    private static final OSFileSystem singleton = new OSFileSystem();

    public static OSFileSystem getOSFileSystem() {
        return singleton;
    }

    private OSFileSystem() {
        super();
    }

    private native static void oneTimeInitializationImpl();

    private final void validateLockArgs(int type, long start, long length) {
        if ((type != IFileSystem.SHARED_LOCK_TYPE)
                && (type != IFileSystem.EXCLUSIVE_LOCK_TYPE)) {
            throw new IllegalArgumentException("Illegal lock type requested."); //$NON-NLS-1$
        }

        // Start position
        if (start < 0) {
            throw new IllegalArgumentException(
                    "Lock start position must be non-negative"); //$NON-NLS-1$
        }

        // Length of lock stretch
        if (length < 0) {
            throw new IllegalArgumentException(
                    "Lock length must be non-negative"); //$NON-NLS-1$
        }
    }

    private native int lockImpl(long fileDescriptor, long start, long length,
            int type, boolean wait);

    /**
     * Returns the granularity for virtual memory allocation.
     * Note that this value for Windows differs from the one for the
     * page size (64K and 4K respectively).
     */
    public native int getAllocGranularity() throws IOException;

    public boolean lock(long fileDescriptor, long start, long length, int type,
            boolean waitFlag) throws IOException {
        // Validate arguments
        validateLockArgs(type, start, length);
        int result = lockImpl(fileDescriptor, start, length, type, waitFlag);
        return result != -1;
    }

    private native int unlockImpl(long fileDescriptor, long start, long length);

    public void unlock(long fileDescriptor, long start, long length)