void
bsd_utaskbootstrap(void)
{
thread_t thread;
struct uthread *ut;
/*
* Clone the bootstrap process from the kernel process, without
* inheriting either task characteristics or memory from the kernel;
*/
thread = cloneproc(TASK_NULL, COALITION_NULL, kernproc, FALSE, TRUE);
/* Hold the reference as it will be dropped during shutdown */
initproc = proc_find(1);
#if __PROC_INTERNAL_DEBUG
if (initproc == PROC_NULL)
panic("bsd_utaskbootstrap: initproc not set\n");
#endif
/*
* Since we aren't going back out the normal way to our parent,
* we have to drop the transition locks explicitly.
*/
proc_signalend(initproc, 0);
proc_transend(initproc, 0);
ut = (struct uthread *)get_bsdthread_info(thread);
ut->uu_sigmask = 0;
act_set_astbsd(thread);
proc_clear_return_wait(initproc, thread);
}
/*
* fork
*
* Description: fork system call.
*
* Parameters: parent Parent process to fork
* uap (void) [unused]
* retval Return value
*
* Returns: 0 Success
* EAGAIN Resource unavailable, try again
*
* Notes: Attempts to create a new child process which inherits state
* from the parent process. If successful, the call returns
* having created an initially suspended child process with an
* extra Mach task and thread reference, for which the thread
* is initially suspended. Until we resume the child process,
* it is not yet running.
*
* The return information to the child is contained in the
* thread state structure of the new child, and does not
* become visible to the child through a normal return process,
* since it never made the call into the kernel itself in the
* first place.
*
* After resuming the thread, this function returns directly to
* the parent process which invoked the fork() system call.
*
* Important: The child thread_resume occurs before the parent returns;
* depending on scheduling latency, this means that it is not
* deterministic as to whether the parent or child is scheduled
* to run first. It is entirely possible that the child could
* run to completion prior to the parent running.
*/
int
fork(proc_t parent_proc, __unused struct fork_args *uap, int32_t *retval)
{
thread_t child_thread;
int err;
retval[1] = 0; /* flag parent return for user space */
if ((err = fork1(parent_proc, &child_thread, PROC_CREATE_FORK, NULL)) == 0) {
task_t child_task;
proc_t child_proc;
/* Return to the parent */
child_proc = (proc_t)get_bsdthreadtask_info(child_thread);
retval[0] = child_proc->p_pid;
/*
* Drop the signal lock on the child which was taken on our
* behalf by forkproc()/cloneproc() to prevent signals being
* received by the child in a partially constructed state.
*/
proc_signalend(child_proc, 0);
proc_transend(child_proc, 0);
/* flag the fork has occurred */
proc_knote(parent_proc, NOTE_FORK | child_proc->p_pid);
DTRACE_PROC1(create, proc_t, child_proc);
#if CONFIG_DTRACE
if ((dtrace_proc_waitfor_hook = dtrace_proc_waitfor_exec_ptr) != NULL)
(*dtrace_proc_waitfor_hook)(child_proc);
#endif
/* "Return" to the child */
proc_clear_return_wait(child_proc, child_thread);
/* drop the extra references we got during the creation */
if ((child_task = (task_t)get_threadtask(child_thread)) != NULL) {
task_deallocate(child_task);
}
thread_deallocate(child_thread);
}
return(err);
}
