Help with segmentation fault please!

I have an assignment to implement a module for something called a SIX Lock. It's basically a complex locking mechanism used for concurrent data access. In any case I'm getting a segmentation fault that I've traced to one line of code but cannot figure out why!

So I have this "class" implementing this SIXlock structure as defined below:

Code:

typedef struct
{
	pthread_mutex_t mutex;			/*our mutex*/
	pthread_cond_t not_locked;		/*cond variable */
	SIXlock_mode_t groupMode;		/*our overall group mode*/
	pthread_t *myThreads;			/*pointer to threads*/
	SIXlock_mode_t *grantedMode;	/*lock mode of each thread */
	int numThreads;				/*number of threads in array*/

} SIXlock_lock_t;

Yup...I'm using the pthreads library and that's about it.
So I have this create function which starts off like this:

Code:

/*-------------------------------------------------------------------------
/Function: 	SIXlock_create
/Input:		Pointer to a SIXlock object
/Output:	Returns parameter pointer pointing to created lock
/		Returns SIXlock_result_t notifying the user of the success/failure
-------------------------------------------------------------------------*/
SIXlock_result_t SIXlock_create(SIXlock_lock_t **lockPointer)
{
	int i;
	lockPointer = NULL;

	/*setup memory allocation*/
	lockPointer = (SIXlock_lock_t **)malloc(sizeof( SIXlock_lock_t ));

	/*if error, return result*/
	if(lockPointer == NULL)
		return SIXLOCK_RESULT_ERROR_MALLOC;
	
	/*initialize*/
	pthread_mutex_init(&((*lockPointer)->mutex), NULL);

....

}

but when it gets to the:

pthread_mutex_init(&((*lockPointer)->mutex), NULL);

line, it throws a segmentation fault. Can someone please help????

You haven't got the right indirection when setting your lockpointer - it should be

Code:

*lockpointer = malloc(...);

Note also that you SHOULD NOT cast malloc in C - if you are using a C++ compiler, then it may be acceptable (but then you should be using new/delete!)

Edit: And of course the

Code:

lockpointer = NULL;

should be

Code:

*lockpointer = NULL;

--
Mats

Thanks! Wow...don't know how I couldn't figure that one out