互斥锁与条件变量实现读写锁----my_pthread_rwlock_init

#include "../unipc.h"
#include "pthread_rwlock.h"



int my_pthread_rwlock_init(my_pthread_rwlock_t *rw, my_pthread_rwlockattr_t *attr)
{
    int rc = -1;

    if(attr != NULL)
        return EINVAL;

    rc = pthread_mutex_init(&rw->rw_mutex,NULL);
    if(rc != 0) {
        printf("pthread_mutex_init error:%s\n",strerror(errno));
        goto err1;
    }

    rc = pthread_cond_init(&rw->rw_condreaders,NULL);
    if(rc != 0) {
        printf("pthread_cond_init readers error:%s\n",strerror(errno));
        goto err2;
    }

    rc = pthread_cond_init(&rw->rw_condwriters,NULL);
    if(rc != 0) {
        printf("pthread_cond_init writers error:%s\n",strerror(errno));
        goto err3;
    }

    rw->rw_magic = RW_MAGIC;
    rw->rw_nwaitreaders = 0;
    rw->rw_nwaitwriters = 0;
    rw->rw_refcount = 0;
    return 0;

err3:
    pthread_cond_destroy(&rw->rw_condreaders);
err2:
    pthread_mutex_destroy(&rw->rw_mutex);
err1:
    return rc;

}