/*!
* Decrement (lock) semaphore value by 1 (if not 0 when thread is blocked)
* \param sem Semaphore descriptor (user level descriptor)
* \return 0 if successful, -1 otherwise and appropriate error number is set
*/
int sys__sem_wait ( sem_t *sem )
{
ksem_t *ksem;
kobject_t *kobj;
kthread_t *kthread;
SYS_ENTRY();
ASSERT_ERRNO_AND_EXIT ( sem, EINVAL );
kthread = kthread_get_active ();
kobj = sem->ptr;
ASSERT_ERRNO_AND_EXIT ( kobj, EINVAL );
ASSERT_ERRNO_AND_EXIT ( list_find ( &kobjects, &kobj->list ),
EINVAL );
ksem = kobj->kobject;
ASSERT_ERRNO_AND_EXIT ( ksem && ksem->id == sem->id, EINVAL );
kthread_set_errno ( kthread, EXIT_SUCCESS );
kthread_set_syscall_retval ( kthread, EXIT_SUCCESS );
if ( ksem->sem_value > 0 )
{
ksem->sem_value--;
ksem->last_lock = kthread;
}
else {
kthread_enqueue ( kthread, &ksem->queue );
kthreads_schedule ();
}
SYS_EXIT ( kthread_get_errno(NULL), kthread_get_syscall_retval(NULL) );
}
/*!
* Wait on conditional variable
* \param cond conditional variable descriptor (user level descriptor)
* \param mutex Mutex descriptor (user level descriptor)
* \return 0 if successful, -1 otherwise and appropriate error number is set
*/
int sys__pthread_cond_wait ( pthread_cond_t *cond, pthread_mutex_t *mutex )
{
kpthread_cond_t *kcond;
kpthread_mutex_t *kmutex;
kobject_t *kobj_cond, *kobj_mutex;
SYS_ENTRY();
ASSERT_ERRNO_AND_EXIT ( cond && mutex, EINVAL );
kobj_cond = cond->ptr;
ASSERT_ERRNO_AND_EXIT ( kobj_cond, EINVAL );
ASSERT_ERRNO_AND_EXIT ( list_find ( &kobjects, &kobj_cond->list ),
EINVAL );
kcond = kobj_cond->kobject;
ASSERT_ERRNO_AND_EXIT ( kcond && kcond->id == cond->id, EINVAL );
kobj_mutex = mutex->ptr;
ASSERT_ERRNO_AND_EXIT ( kobj_mutex, EINVAL );
ASSERT_ERRNO_AND_EXIT ( list_find ( &kobjects, &kobj_mutex->list),
EINVAL );
kmutex = kobj_mutex->kobject;
ASSERT_ERRNO_AND_EXIT ( kmutex && kmutex->id == mutex->id, EINVAL );
ASSERT_ERRNO_AND_EXIT ( kmutex->owner == kthread_get_active(), EPERM );
kthread_set_errno ( NULL, EXIT_SUCCESS );
kthread_set_syscall_retval ( NULL, EXIT_SUCCESS );
/* move thread in conditional variable queue */
kthread_enqueue ( NULL, &kcond->queue );
/* save reference to mutex object */
kthread_set_private_param ( NULL, kobj_mutex );
/* release mutex */
kmutex->owner = kthreadq_get ( &kmutex->queue );
if ( kmutex->owner )
kthreadq_release ( &kmutex->queue );
kthreads_schedule ();
SYS_EXIT ( kthread_get_errno(NULL), kthread_get_syscall_retval(NULL) );
}
/*!
* Increment (lock) semaphore value by 1 (or unblock one thread that is blocked)
* \param sem Semaphore descriptor (user level descriptor)
* \return 0 if successful, -1 otherwise and appropriate error number is set
*/
int sys__sem_post ( sem_t *sem )
{
ksem_t *ksem;
kobject_t *kobj;
kthread_t *kthread, *released;
SYS_ENTRY();
ASSERT_ERRNO_AND_EXIT ( sem, EINVAL );
kthread = kthread_get_active ();
kobj = sem->ptr;
ASSERT_ERRNO_AND_EXIT ( kobj, EINVAL );
ASSERT_ERRNO_AND_EXIT ( list_find ( &kobjects, &kobj->list ),
EINVAL );
ksem = kobj->kobject;
ASSERT_ERRNO_AND_EXIT ( ksem && ksem->id == sem->id, EINVAL );
kthread_set_errno ( kthread, EXIT_SUCCESS );
kthread_set_syscall_retval ( kthread, EXIT_SUCCESS );
released = kthreadq_get ( &ksem->queue ); /* first to release */
if ( !released || ksem->sem_value < 0 )
{
/* if initial semaphore value (set by sem_init) was negative,
* semaphore will not release threads until its value
* reaches zero (small extension of POSIX semaphore) */
ksem->sem_value++;
}
else {
kthreadq_release ( &ksem->queue );
kthreads_schedule ();
}
SYS_EXIT ( kthread_get_errno(NULL), kthread_get_syscall_retval(NULL) );
}
/*!
* Wait for thread termination
* \param thread Thread descriptor (user level descriptor)
* \param retval Where to store exit status of joined thread
* \return 0 if thread already gone; -1 if not finished and 'wait' not set;
* 'thread exit status' otherwise
*/
int sys__pthread_join ( pthread_t *thread, void **retval )
{
kthread_t *kthread;
SYS_ENTRY();
ASSERT_ERRNO_AND_EXIT ( thread, ESRCH );
kthread = thread->ptr;
if ( kthread_get_id (kthread) != thread->id )
{
/* at 'kthread' is now something else */
SYS_EXIT ( ESRCH, EXIT_FAILURE );
}
else if ( kthread_is_alive (kthread) )
{
kthread_set_errno ( NULL, EXIT_SUCCESS );
kthread_set_syscall_retval ( NULL, EXIT_SUCCESS );
kthread_set_private_param ( kthread_get_active(), retval );
kthread_wait_thread ( NULL, kthread );
kthreads_schedule ();
SYS_EXIT ( kthread_get_errno(NULL),
kthread_get_syscall_retval(NULL) );
}
else {
/* target thread is passive, collect status and free descr. */
kthread_collect_status ( kthread, retval );
SYS_EXIT ( EXIT_SUCCESS, EXIT_SUCCESS );
}
}
int sys__get_errno ( void *p )
{
return kthread_get_errno (NULL);
}
int sys__get_errno ()
{
SYS_ENTRY();
SYS_RETURN ( kthread_get_errno (NULL) );
}
