asmlinkage long sys_semget (key_t key, int nsems, int semflg)
{
int id, err = -EINVAL;
struct sem_array *sma;
if (nsems < 0 || nsems > sc_semmsl)
return -EINVAL;
down(&sem_ids.sem);
if (key == IPC_PRIVATE) {
err = newary(key, nsems, semflg);
} else if ((id = ipc_findkey(&sem_ids, key)) == -1) { /* key not used */
if (!(semflg & IPC_CREAT))
err = -ENOENT;
else
err = newary(key, nsems, semflg);
} else if (semflg & IPC_CREAT && semflg & IPC_EXCL) {
err = -EEXIST;
} else {
sma = sem_lock(id);
if(sma==NULL)
BUG();
if (nsems > sma->sem_nsems)
err = -EINVAL;
else if (ipcperms(&sma->sem_perm, semflg))
err = -EACCES;
else
err = sem_buildid(id, sma->sem_perm.seq);
sem_unlock(id);
}
up(&sem_ids.sem);
return err;
}
asmlinkage int sys_semget (key_t key, int nsems, int semflg)
{
int id, err = -EINVAL;
struct semid_ds *sma;
lock_kernel();
if (nsems < 0 || nsems > SEMMSL)
goto out;
if (key == IPC_PRIVATE) {
err = newary(key, nsems, semflg);
} else if ((id = findkey (key)) == -1) { /* key not used */
if (!(semflg & IPC_CREAT))
err = -ENOENT;
else
err = newary(key, nsems, semflg);
} else if (semflg & IPC_CREAT && semflg & IPC_EXCL) {
err = -EEXIST;
} else {
sma = semary[id];
if (nsems > sma->sem_nsems)
err = -EINVAL;
else if (ipcperms(&sma->sem_perm, semflg))
err = -EACCES;
else
err = (int) sma->sem_perm.seq * SEMMNI + id;
}
out:
unlock_kernel();
return err;
}
/* 从系统中获取一个信号量 */
int sys_semget (key_t key, int nsems, int semflg)
{
int id;
struct semid_ds *sma;
if (nsems < 0 || nsems > SEMMSL)
return -EINVAL;
if (key == IPC_PRIVATE)
return newary(key, nsems, semflg);
if ((id = findkey (key)) == -1) { /* key not used */
/* 对应key的信号量没有找到，又不是创建标记则出错，否则创建一个新的 */
if (!(semflg & IPC_CREAT))
return -ENOENT;
return newary(key, nsems, semflg);
}
if (semflg & IPC_CREAT && semflg & IPC_EXCL)
return -EEXIST;
sma = semary[id];
if (nsems > sma->sem_nsems)
return -EINVAL;
if (ipcperms(&sma->sem_perm, semflg))
return -EACCES;
/* 和newary返回联系 */
return sma->sem_perm.seq*SEMMNI + id;
}
int sys_semget (key_t key, int nsems, int semflg)
{
int id;
struct semid_ds *sma;
if (nsems < 0 || nsems > SEMMSL)
return -EINVAL;
if (key == IPC_PRIVATE)
return newary(key, nsems, semflg);
if ((id = findkey (key)) == -1) { /* key not used */
if (!(semflg & IPC_CREAT))
return -ENOENT;
return newary(key, nsems, semflg);
}
if (semflg & IPC_CREAT && semflg & IPC_EXCL)
return -EEXIST;
sma = semary[id];
if (nsems > sma->sem_nsems)
return -EINVAL;
if (ipcperms(&sma->sem_perm, semflg))
return -EACCES;
return (unsigned int) sma->sem_perm.seq * SEMMNI + id;
}
