iaik.pkcs.pkcs11.DefaultMutexHandler Maven / Gradle / Ivy
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package iaik.pkcs.pkcs11;
import iaik.pkcs.pkcs11.wrapper.PKCS11Constants;
import sun.security.pkcs11.wrapper.PKCS11Exception;
/**
* This class offers a default-implementation of a MutexHandler.
*
* @author Karl Scheibelhofer
* @version 1.0
* @invariants
*/
@SuppressWarnings("restriction")
public class DefaultMutexHandler implements MutexHandler {
/**
* A simple mutex implementation, but it satisfies the requirements stated
* in PKCS#11 v2.11.
*
* @author Karl
* Scheibelhofer
* @version 1.0
* @invariants
*/
class Mutex {
/**
* Indicates that this mutex is currently locked.
*/
protected boolean locked_;
/**
* Default constructor.
*
* @preconditions
* @postconditions (locked_ == false)
*/
public Mutex() {
locked_ = false;
}
/**
* Locks this mutex. Waits until the mutex gets unlocked, if
* it is already locked.
*
* @exception InterruptedException
* If the current thread has been interrupted.
* @preconditions
* @postconditions (locked_ == true)
*/
public synchronized void lock()
throws InterruptedException {
if (Thread.interrupted()) {
throw new InterruptedException();
}
try {
while (locked_) {
wait();
}
locked_ = true;
} catch (InterruptedException ex) {
notify();
throw ex;
}
}
/**
* Unlocks this mutex. It returns the previous lock-state.
*
* @return True, if the mutex was locked. False, otherwise.
* @preconditions
* @postconditions (locked_ == false)
* and (result == locked_@pre)
*/
public synchronized boolean unlock() {
boolean previousState = locked_;
locked_ = false;
notify();
return previousState;
}
/**
* Returns the string representation of this object.
*
* @return the string representation of this object
*/
public String toString() {
return ((locked_) ? "locked" : "unlocked");
}
}
/**
* Create a new mutex object.
*
* @return The new mutex object.
* @exception PKCS11Exception
* If the wrapper should return a different value than CKR_OK
* to the library. It gets the error-code and returns it as
* CK_RV.
* @preconditions
* @postconditions (result <> null)
*/
@Override
public Object createMutex()
throws PKCS11Exception {
return new Mutex();
}
/**
* Destroy a mutex object.
*
* @param mutex
* The mutex object to destroy.
* @exception PKCS11Exception
* If the wrapper should return a different value than CKR_OK
* to the library. It gets the error-code and returns it as
* CK_RV.
* @preconditions (mutex <> null)
* @postconditions
*/
@Override
public void destroyMutex(Object mutex)
throws PKCS11Exception {
// trust in the garbage collector
}
/**
* If this method is called on with a mutex object which is not locked, the
* calling thread obtains a lock on that mutex object and returns.
* If this method is called with a mutex object which is locked by some
* thread other than the calling thread, the calling thread blocks and waits
* for that mutex to be unlocked.
* If this method is called with a a mutex object which is locked by the
* calling thread, the behavior of this method call is undefined.
*
* @param mutex
* The mutex object to lock.
* @exception PKCS11Exception
* If the wrapper should return a different value than CKR_OK
* to the library. It gets the error-code and returns it as
* CK_RV.
* @preconditions (mutex <> null)
* @postconditions
*/
@Override
public void lockMutex(Object mutex)
throws PKCS11Exception {
try {
Mutex castedMutex = (Mutex) mutex;
while (true) {
try {
castedMutex.lock();
break;
} catch (InterruptedException ex) {
// try again, until we succeed
}
}
} catch (ClassCastException ex) {
throw new PKCS11Exception(PKCS11Constants.CKR_MUTEX_BAD);
}
}
/**
* If this method is called with a mutex object which is locked by the
* calling thread, that mutex object is unlocked and the function call
* returns. Furthermore: If exactly one thread was blocking on that
* particular mutex object, then that thread stops blocking, obtains a lock
* on that mutex object, and its lockMutex(Object) call returns.
* If more than one thread was blocking on that particular mutex object,
* then exactly one of the blocking threads is selected somehow. That lucky
* thread stops blocking, obtains a lock on the mutex object, and its
* lockMutex(Object) call returns. All other threads blocking on that
* particular mutex object continue to block.
* If this method is called with a mutex object which is not locked, then
* the method call throws an exception with the error code
* PKCS11Constants.CKR_mutex_NOT_LOCKED.
* If this method is called with a mutex object which is locked by some
* thread other than the calling thread, the behavior of this method call is
* undefined.
*
* @param mutex
* The mutex object to unlock.
* @exception PKCS11Exception
* If the wrapper should return a different value than CKR_OK
* to the library. It gets the error-code and returns it as
* CK_RV.
* @preconditions (mutex <> null)
* @postconditions
*/
@Override
public void unlockMutex(Object mutex)
throws PKCS11Exception {
try {
Mutex castedMutex = (Mutex) mutex;
castedMutex.unlock();
} catch (ClassCastException ex) {
throw new PKCS11Exception(PKCS11Constants.CKR_MUTEX_BAD);
}
}
}
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