l3.libnazgul/src/queueInit.c

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

msgQueue * queueInit(msgSpaceId externId, int queueIdx) {
	int queueFd;
	msgQueue * queue;
	sem_t * semProtectFd;
	msgQueueSemId queueSemProtectId;
	sem_t * semReadableFd;
	msgQueueSemId queueSemReadableId;
	msgQueueId queueId;

	queue = NULL;

	msgQueueProtSemIdIntern(queueSemProtectId,externId,queueIdx);
	msgQueueReadSemIdIntern(queueSemReadableId,externId,queueIdx);
 
	// creation du semaphore de lecture 
	semReadableFd = sem_open(queueSemReadableId, 
		O_CREAT|O_EXCL, SEM_DEFAULT_MODE, 0);
	if(semReadableFd == SEM_FAILED) {
	  NZG_ERROR("sem_open", queueSemReadableId);
	  goto ERROR;
	}
	
	// creation du semaphore de protection
	semProtectFd = sem_open(queueSemProtectId, 
		O_CREAT|O_EXCL, SEM_DEFAULT_MODE, 1);
	if(semProtectFd == SEM_FAILED) {
	  NZG_ERROR("sem_open", queueSemProtectId);
	  goto ERROR;
	}

	if(sem_wait(semProtectFd)==-1){
	  NZG_ERROR("sem_wait",queueSemProtectId);
	  goto ERROR;
	}

	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);



	/* on ferme tout ce qu'il faut */
	sem_close(semProtectFd);
	close(queueFd);

	return queue;
ERROR:
	return NULL;

}