int sys_exec(char* filename)
{
tid_t tid = process_execute(filename);
if(tid == -1) // process execute failed, return -1
return -1;
else // tid is valid
{
intr_disable();
thread_block(); // block myself, until child wakes me up
// with the exec_status, telling me if the elf load was successful
intr_enable();
struct thread* child = get_thread_from_tid(tid);
if(child)
{
// exec_status will be -1 if load failed, hence we return -1
// in such case
tid = child->exec_status;
child->parent_waiting_exec = 0;
// child had blocked itself, unblock it
thread_unblock(child);
}
return tid;
}
}
/* handle a SIGCHLD signal */
void sigchld_callback(void)
{
int pid, status;
for (;;)
{
if (!(pid = waitpid( -1, &status, WUNTRACED | WNOHANG | __WALL ))) break;
if (pid != -1)
{
struct thread *thread = get_thread_from_tid( pid );
if (!thread) thread = get_thread_from_pid( pid );
handle_child_status( thread, pid, status, -1 );
}
else break;
}
}
