void group_removechildren(FAR struct task_group_s *group)
{
FAR struct child_status_s *curr;
FAR struct child_status_s *next;
/* Remove all child structures for the TCB and return them to the freelist */
for (curr = group->tg_children; curr; curr = next) {
next = curr->flink;
group_freechild(curr);
}
group->tg_children = NULL;
group_dumpchildren(group, "group_removechildren");
}
int task_reparent(pid_t ppid, pid_t chpid)
{
#ifdef CONFIG_SCHED_CHILD_STATUS
FAR struct child_status_s *child;
#endif
FAR struct task_group_s *chgrp;
FAR struct task_group_s *ogrp;
FAR struct task_group_s *pgrp;
struct tcb_s *tcb;
gid_t ogid;
gid_t pgid;
irqstate_t flags;
int ret;
/* Disable interrupts so that nothing can change in the relatinoship of
* the three task: Child, current parent, and new parent.
*/
flags = irqsave();
/* Get the child tasks task group */
tcb = sched_gettcb(chpid);
if (!tcb)
{
ret = -ECHILD;
goto errout_with_ints;
}
DEBUGASSERT(tcb->group);
chgrp = tcb->group;
/* Get the GID of the old parent task's task group (ogid) */
ogid = chgrp->tg_pgid;
/* Get the old parent task's task group (ogrp) */
ogrp = group_findbygid(ogid);
if (!ogrp)
{
ret = -ESRCH;
goto errout_with_ints;
}
/* If new parent task's PID (ppid) is zero, then new parent is the
* grandparent will be the new parent, i.e., the parent of the current
* parent task.
*/
if (ppid == 0)
{
/* Get the grandparent task's task group (pgrp) */
pgid = ogrp->tg_pgid;
pgrp = group_findbygid(pgid);
}
else
{
/* Get the new parent task's task group (pgrp) */
tcb = sched_gettcb(ppid);
if (!tcb)
{
ret = -ESRCH;
goto errout_with_ints;
}
pgrp = tcb->group;
pgid = pgrp->tg_gid;
}
if (!pgrp)
{
ret = -ESRCH;
goto errout_with_ints;
}
/* Then reparent the child. Notice that we don't actually change the
* parent of the task. Rather, we change the parent task group for
* all members of the child's task group.
*/
chgrp->tg_pgid = pgid;
#ifdef CONFIG_SCHED_CHILD_STATUS
/* Remove the child status entry from old parent task group */
child = group_removechild(ogrp, chpid);
if (child)
{
/* Has the new parent's task group supressed child exit status? */
if ((pgrp->tg_flags && GROUP_FLAG_NOCLDWAIT) == 0)
{
/* No.. Add the child status entry to the new parent's task group */
group_addchild(pgrp, child);
}
else
{
/* Yes.. Discard the child status entry */
group_freechild(child);
}
/* Either case is a success */
ret = OK;
}
else
{
/* This would not be an error if the original parent's task group has
* suppressed child exit status.
*/
ret = ((ogrp->tg_flags && GROUP_FLAG_NOCLDWAIT) == 0) ? -ENOENT : OK;
}
#else /* CONFIG_SCHED_CHILD_STATUS */
DEBUGASSERT(otcb->nchildren > 0);
otcb->nchildren--; /* The orignal parent now has one few children */
ptcb->nchildren++; /* The new parent has one additional child */
ret = OK;
#endif /* CONFIG_SCHED_CHILD_STATUS */
errout_with_ints:
irqrestore(flags);
return ret;
}
int task_reparent(pid_t ppid, pid_t chpid)
{
#ifdef CONFIG_SCHED_CHILD_STATUS
FAR struct child_status_s *child;
#endif
struct tcb_s *ptcb;
struct tcb_s *chtcb;
struct tcb_s *otcb;
pid_t opid;
irqstate_t flags;
int ret;
/* Disable interrupts so that nothing can change in the relatinoship of
* the three task: Child, current parent, and new parent.
*/
flags = irqsave();
/* Get the child tasks TCB (chtcb) */
chtcb = sched_gettcb(chpid);
if (!chtcb)
{
ret = -ECHILD;
goto errout_with_ints;
}
/* Get the PID of the child task's parent (opid) */
opid = chtcb->ppid;
/* Get the TCB of the child task's parent (otcb) */
otcb = sched_gettcb(opid);
if (!otcb)
{
ret = -ESRCH;
goto errout_with_ints;
}
/* If new parent task's PID (ppid) is zero, then new parent is the
* grandparent will be the new parent, i.e., the parent of the current
* parent task.
*/
if (ppid == 0)
{
ppid = otcb->ppid;
}
/* Get the new parent task's TCB (ptcb) */
ptcb = sched_gettcb(ppid);
if (!ptcb)
{
ret = -ESRCH;
goto errout_with_ints;
}
/* Then reparent the child */
chtcb->ppid = ppid; /* The task specified by ppid is the new parent */
#ifdef CONFIG_SCHED_CHILD_STATUS
/* Remove the child status entry from old parent TCB */
child = group_removechild(otcb->group, chpid);
if (child)
{
/* Has the new parent's task group supressed child exit status? */
if ((ptcb->group->tg_flags && GROUP_FLAG_NOCLDWAIT) == 0)
{
/* No.. Add the child status entry to the new parent's task group */
group_addchild(ptcb->group, child);
}
else
{
/* Yes.. Discard the child status entry */
group_freechild(child);
}
/* Either case is a success */
ret = OK;
}
else
{
/* This would not be an error if the original parent's task group has
* suppressed child exit status.
*/
ret = ((otcb->group->tg_flags && GROUP_FLAG_NOCLDWAIT) == 0) ? -ENOENT : OK;
}
#else /* CONFIG_SCHED_CHILD_STATUS */
DEBUGASSERT(otcb->nchildren > 0);
otcb->nchildren--; /* The orignal parent now has one few children */
ptcb->nchildren++; /* The new parent has one additional child */
ret = OK;
#endif /* CONFIG_SCHED_CHILD_STATUS */
errout_with_ints:
irqrestore(flags);
return ret;
}
pid_t waitpid(pid_t pid, int *stat_loc, int options)
{
FAR struct tcb_s *rtcb = this_task();
FAR struct tcb_s *ctcb;
#ifdef CONFIG_SCHED_CHILD_STATUS
FAR struct child_status_s *child;
bool retains;
#endif
FAR struct siginfo info;
sigset_t set;
int errcode;
int ret;
DEBUGASSERT(stat_loc);
/* waitpid() is a cancellation point */
(void)enter_cancellation_point();
/* None of the options are supported */
#ifdef CONFIG_DEBUG_FEATURES
if (options != 0)
{
set_errno(ENOSYS);
leave_cancellation_point();
return ERROR;
}
#endif
/* Create a signal set that contains only SIGCHLD */
(void)sigemptyset(&set);
(void)sigaddset(&set, SIGCHLD);
/* Disable pre-emption so that nothing changes while the loop executes */
sched_lock();
/* Verify that this task actually has children and that the requested PID
* is actually a child of this task.
*/
#ifdef CONFIG_SCHED_CHILD_STATUS
/* Does this task retain child status? */
retains = ((rtcb->group->tg_flags && GROUP_FLAG_NOCLDWAIT) == 0);
if (rtcb->group->tg_children == NULL && retains)
{
errcode = ECHILD;
goto errout_with_errno;
}
else if (pid != (pid_t)-1)
{
/* Get the TCB corresponding to this PID and make sure that the
* thread it is our child.
*/
ctcb = sched_gettcb(pid);
#ifdef HAVE_GROUP_MEMBERS
if (ctcb == NULL || ctcb->group->tg_pgid != rtcb->group->tg_gid)
#else
if (ctcb == NULL || ctcb->group->tg_ppid != rtcb->pid)
#endif
{
errcode = ECHILD;
goto errout_with_errno;
}
/* Does this task retain child status? */
if (retains)
{
/* Check if this specific pid has allocated child status? */
if (group_findchild(rtcb->group, pid) == NULL)
{
errcode = ECHILD;
goto errout_with_errno;
}
}
}
#else /* CONFIG_SCHED_CHILD_STATUS */
if (rtcb->group->tg_nchildren == 0)
{
/* There are no children */
errcode = ECHILD;
goto errout_with_errno;
}
else if (pid != (pid_t)-1)
{
/* Get the TCB corresponding to this PID and make sure that the
* thread it is our child.
*/
ctcb = sched_gettcb(pid);
#ifdef HAVE_GROUP_MEMBERS
if (ctcb == NULL || ctcb->group->tg_pgid != rtcb->group->tg_gid)
#else
if (ctcb == NULL || ctcb->group->tg_ppid != rtcb->pid)
#endif
{
errcode = ECHILD;
goto errout_with_errno;
}
}
#endif /* CONFIG_SCHED_CHILD_STATUS */
/* Loop until the child that we are waiting for dies */
for (; ; )
{
#ifdef CONFIG_SCHED_CHILD_STATUS
/* Check if the task has already died. Signals are not queued in
* NuttX. So a possibility is that the child has died and we
* missed the death of child signal (we got some other signal
* instead).
*/
if (pid == (pid_t)-1)
{
/* We are waiting for any child, check if there are still
* chilren.
*/
DEBUGASSERT(!retains || rtcb->group->tg_children);
if (retains && (child = group_exitchild(rtcb->group)) != NULL)
{
/* A child has exited. Apparently we missed the signal.
* Return the saved exit status.
*/
/* The child has exited. Return the saved exit status */
*stat_loc = child->ch_status << 8;
/* Discard the child entry and break out of the loop */
(void)group_removechild(rtcb->group, child->ch_pid);
group_freechild(child);
break;
}
}
/* We are waiting for a specific PID. Does this task retain child status? */
else if (retains)
{
/* Get the current status of the child task. */
child = group_findchild(rtcb->group, pid);
DEBUGASSERT(child);
/* Did the child exit? */
if ((child->ch_flags & CHILD_FLAG_EXITED) != 0)
{
/* The child has exited. Return the saved exit status */
*stat_loc = child->ch_status << 8;
/* Discard the child entry and break out of the loop */
(void)group_removechild(rtcb->group, pid);
group_freechild(child);
break;
}
}
else
{
/* We can use kill() with signal number 0 to determine if that
* task is still alive.
*/
ret = kill(pid, 0);
if (ret < 0)
{
/* It is no longer running. We know that the child task
* was running okay when we started, so we must have lost
* the signal. In this case, we know that the task exit'ed,
* but we do not know its exit status. It would be better
* to reported ECHILD than bogus status.
*/
errcode = ECHILD;
goto errout_with_errno;
}
}
#else /* CONFIG_SCHED_CHILD_STATUS */
/* Check if the task has already died. Signals are not queued in
* NuttX. So a possibility is that the child has died and we
* missed the death of child signal (we got some other signal
* instead).
*/
if (rtcb->group->tg_nchildren == 0 ||
(pid != (pid_t)-1 && (ret = kill(pid, 0)) < 0))
{
/* We know that the child task was running okay we stared,
* so we must have lost the signal. What can we do?
* Let's return ECHILD.. that is at least informative.
*/
errcode = ECHILD;
goto errout_with_errno;
}
#endif /* CONFIG_SCHED_CHILD_STATUS */
/* Wait for any death-of-child signal */
ret = sigwaitinfo(&set, &info);
if (ret < 0)
{
goto errout_with_lock;
}
/* Was this the death of the thread we were waiting for? In the of
* pid == (pid_t)-1, we are waiting for any child thread.
*/
if (info.si_signo == SIGCHLD &&
(pid == (pid_t)-1 || info.si_pid == pid))
{
/* Yes... return the status and PID (in the event it was -1) */
*stat_loc = info.si_status << 8;
pid = info.si_pid;
break;
}
}
leave_cancellation_point();
sched_unlock();
return (int)pid;
errout_with_errno:
set_errno(errcode);
errout_with_lock:
leave_cancellation_point();
sched_unlock();
return ERROR;
}
