jcs.org
Serenity Operating System
1/*
2 * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
3 * Copyright (c) 2021, sin-ack <sin-ack@protonmail.com>
4 *
5 * SPDX-License-Identifier: BSD-2-Clause
6 */
7
8#pragma once
9
10#include <AK/Badge.h>
11#include <AK/Checked.h>
12#include <AK/CircularQueue.h>
13#include <AK/HashMap.h>
14#include <AK/NonnullOwnPtr.h>
15#include <Kernel/API/InodeWatcherEvent.h>
16#include <Kernel/FileSystem/File.h>
17#include <Kernel/Forward.h>
18
19namespace Kernel {
20
21// A specific description of a watch.
22struct WatchDescription {
23 int wd;
24 Inode& inode;
25 unsigned event_mask;
26
27 static ErrorOr<NonnullOwnPtr<WatchDescription>> create(int wd, Inode& inode, unsigned event_mask)
28 {
29 return adopt_nonnull_own_or_enomem(new (nothrow) WatchDescription(wd, inode, event_mask));
30 }
31
32private:
33 WatchDescription(int wd, Inode& inode, unsigned event_mask)
34 : wd(wd)
35 , inode(inode)
36 , event_mask(event_mask)
37 {
38 }
39};
40
41class InodeWatcher final : public File {
42public:
43 static ErrorOr<NonnullRefPtr<InodeWatcher>> try_create();
44 virtual ~InodeWatcher() override;
45
46 virtual bool can_read(OpenFileDescription const&, u64) const override;
47 virtual ErrorOr<size_t> read(OpenFileDescription&, u64, UserOrKernelBuffer&, size_t) override;
48 // Can't write to an inode watcher.
49 virtual bool can_write(OpenFileDescription const&, u64) const override { return true; }
50 virtual ErrorOr<size_t> write(OpenFileDescription&, u64, UserOrKernelBuffer const&, size_t) override { return EIO; }
51 virtual ErrorOr<void> close() override;
52
53 virtual ErrorOr<NonnullOwnPtr<KString>> pseudo_path(OpenFileDescription const&) const override;
54 virtual StringView class_name() const override { return "InodeWatcher"sv; };
55 virtual bool is_inode_watcher() const override { return true; }
56
57 void notify_inode_event(Badge<Inode>, InodeIdentifier, InodeWatcherEvent::Type, StringView name = {});
58
59 ErrorOr<int> register_inode(Inode&, unsigned event_mask);
60 ErrorOr<void> unregister_by_wd(int);
61 void unregister_by_inode(Badge<Inode>, InodeIdentifier);
62
63private:
64 explicit InodeWatcher() { }
65
66 mutable Mutex m_lock;
67
68 struct Event {
69 int wd { 0 };
70 InodeWatcherEvent::Type type { InodeWatcherEvent::Type::Invalid };
71 OwnPtr<KString> path;
72 };
73 CircularQueue<Event, 32> m_queue;
74 Checked<int> m_wd_counter { 1 };
75
76 // NOTE: These two hashmaps provide two different ways of reaching the same
77 // watch description, so they will overlap.
78 HashMap<int, NonnullOwnPtr<WatchDescription>> m_wd_to_watches;
79 HashMap<InodeIdentifier, WatchDescription*> m_inode_to_watches;
80};
81
82}