ladybird/Kernel/ProcessGroup.h
Andreas Kling 3e30d9bc99 Kernel: Make ProcessGroup a ListedRefCounted and fix two races
This closes two race windows:

- ProcessGroup removed itself from the "all process groups" list in its
  destructor. It was possible to walk the list between the last unref()
  and the destructor invocation, and grab a pointer to a ProcessGroup
  that was about to get deleted.

- sys$setsid() could end up creating a process group that already
  existed, as there was a race window between checking if the PGID
  is used, and actually creating a ProcessGroup with that PGID.
2023-04-05 11:37:27 +02:00

51 lines
1.2 KiB
C++

/*
* Copyright (c) 2020-2023, the SerenityOS developers.
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#pragma once
#include <AK/IntrusiveList.h>
#include <AK/RefPtr.h>
#include <Kernel/Forward.h>
#include <Kernel/Library/ListedRefCounted.h>
#include <Kernel/Library/LockWeakable.h>
#include <Kernel/Locking/SpinlockProtected.h>
#include <Kernel/UnixTypes.h>
namespace Kernel {
class ProcessGroup
: public ListedRefCounted<ProcessGroup, LockType::Spinlock>
, public LockWeakable<ProcessGroup> {
AK_MAKE_NONMOVABLE(ProcessGroup);
AK_MAKE_NONCOPYABLE(ProcessGroup);
public:
~ProcessGroup();
static ErrorOr<NonnullRefPtr<ProcessGroup>> create_if_unused_pgid(ProcessGroupID);
static ErrorOr<NonnullRefPtr<ProcessGroup>> find_or_create(ProcessGroupID);
static RefPtr<ProcessGroup> from_pgid(ProcessGroupID);
ProcessGroupID const& pgid() const { return m_pgid; }
private:
ProcessGroup(ProcessGroupID pgid)
: m_pgid(pgid)
{
}
ProcessGroupID m_pgid;
mutable IntrusiveListNode<ProcessGroup> m_list_node;
public:
using AllInstancesList = IntrusiveList<&ProcessGroup::m_list_node>;
static SpinlockProtected<AllInstancesList, LockRank::None>& all_instances();
};
}