#include "libnazgul.h"
#include "ids.h"

msgQueue * queueInit(msgSpaceId externId, int queueIdx) {
	int queueFd;
	msgQueue * queue;
	sem_t * semaphore;
	msgQueueId queueId;

	queue = NULL;
	
	if(msgQueueIdIntern(queueId, externId, queueIdx) < 0) {
		return NULL;
	}
	
	queueFd = shm_open(queueId, O_RDWR|O_CREAT|O_EXCL|O_TRUNC, MSGSPACE_DEFAULT_MODE);
	if(queueFd == -1) {
		fprintf(stderr, "queueInit : %s initialisation failed: %s\n", queueId, strerror(errno));
		return NULL;
	}

	if(ftruncate(queueFd, sizeof(* queue)) == -1) {
		fprintf( stderr, "Queue resizing failed: %s\n",
			strerror( errno ) );
		return NULL;
  }


	/* on remplit la structure msgQueue */
	queue->elemCounter = 0;
	strcpy(queue->headId,queue->id);
	strcpy(queue->tailId,queue->id);


	
	// creation du semaphore
	semaphore = sem_open(queueId, O_CREAT|O_EXCL, SEM_DEFAULT_MODE, 1);
	if(semaphore == SEM_FAILED) {
		NZG_ERROR("sem_open", queueId);
		goto ERROR;
	}

if(sem_wait(semaphore)==-1){
	NZG_ERROR("sem_wait",queueId);
	goto ERROR;
  }

	/* on ferme tout ce qu'il faut */
	sem_close(semaphore);
	close(queueFd);
	
	return queue;
ERROR:
	return NULL;
	
}