Question

Due to my feeble understanding of allocating type memory to pointers, the following causes a bus error on the call to barrier_create (‘hi’ is never printed).

typedef struct barrier barrier_t; typedef struct barrier *barrier_p;  barrier_p test_barrier_p;  int main(int argc, char *argv[]) {     barrier_create(*test_barrier_p); }  int barrier_create(barrier_p *barrier_pointer) { printf('hi\n');     barrier_p old_barrier, new_barrier;     int count;     old_barrier = (barrier_p) *barrier_pointer;     new_barrier = (barrier_p) malloc(sizeof(*new_barrier));     count = pthread_mutex_init(&new_barrier->lock, NULL);     new_barrier->is_valid = VALID_BARRIER;     new_barrier->counter = 0;     new_barrier->release_flag = 0;     *barrier_pointer = new_barrier;     return HAPPY_HAPPY_JOY_JOY; } 

What am I missing or mis-typing?

Answer 1

barrier_create(*test_barrier_p); 

Since barrier_create takes address of a barrier_p, this should be &test_barrier_p, not *test_barrier_p.

printf('hi\n'); 

Inaccurate test of code reachability because stdout is likely buffered; I’d recommend fprintf(stderr, 'hi\n'); instead.

new_barrier = (barrier_p) malloc(sizeof(*new_barrier)); 

I’d say sizeof(barrier_t). Again a * in an odd place, the _p notation may not be helping your type manipulation clarity.

For pedanticism, I would check the return value of malloc. I see little point in keeping the old value unless to recover in some way from a malloc error.

What is the purpose of count?