jcs.org
Serenity Operating System
1/*
2 * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
3 *
4 * SPDX-License-Identifier: BSD-2-Clause
5 */
6
7#pragma once
8
9// Device is the base class of everything that lives in the /dev directory.
10//
11// To expose a Device to the filesystem, simply pass two unique numbers to the constructor,
12// and then mknod a file in /dev with those numbers.
13//
14// There are two main subclasses:
15// - BlockDevice (random access)
16// - CharacterDevice (sequential)
17#include <AK/DoublyLinkedList.h>
18#include <AK/Error.h>
19#include <AK/Function.h>
20#include <AK/HashMap.h>
21#include <Kernel/Devices/AsyncDeviceRequest.h>
22#include <Kernel/FileSystem/DeviceFileTypes.h>
23#include <Kernel/FileSystem/File.h>
24#include <Kernel/FileSystem/SysFS/Registry.h>
25#include <Kernel/FileSystem/SysFS/Subsystems/DeviceIdentifiers/DeviceComponent.h>
26#include <Kernel/FileSystem/SysFS/Subsystems/DeviceIdentifiers/SymbolicLinkDeviceComponent.h>
27#include <Kernel/Library/LockRefPtr.h>
28#include <Kernel/UnixTypes.h>
29
30namespace Kernel {
31
32class Device : public File {
33protected:
34 enum class State {
35 Normal,
36 BeingRemoved,
37 };
38
39public:
40 virtual ~Device() override;
41
42 MajorNumber major() const { return m_major; }
43 MinorNumber minor() const { return m_minor; }
44
45 virtual ErrorOr<NonnullOwnPtr<KString>> pseudo_path(OpenFileDescription const&) const override;
46 virtual ErrorOr<NonnullRefPtr<OpenFileDescription>> open(int options) override;
47
48 UserID uid() const { return m_uid; }
49 GroupID gid() const { return m_gid; }
50
51 virtual bool is_device() const override { return true; }
52 virtual void will_be_destroyed() override;
53 virtual ErrorOr<void> after_inserting();
54 virtual bool is_openable_by_jailed_processes() const { return false; }
55 void process_next_queued_request(Badge<AsyncDeviceRequest>, AsyncDeviceRequest const&);
56
57 template<typename AsyncRequestType, typename... Args>
58 ErrorOr<NonnullLockRefPtr<AsyncRequestType>> try_make_request(Args&&... args)
59 {
60 auto request = TRY(adopt_nonnull_lock_ref_or_enomem(new (nothrow) AsyncRequestType(*this, forward<Args>(args)...)));
61 SpinlockLocker lock(m_requests_lock);
62 bool was_empty = m_requests.is_empty();
63 TRY(m_requests.try_append(request));
64 if (was_empty)
65 request->do_start(move(lock));
66 return request;
67 }
68
69protected:
70 Device(MajorNumber major, MinorNumber minor);
71 void set_uid(UserID uid) { m_uid = uid; }
72 void set_gid(GroupID gid) { m_gid = gid; }
73
74 void after_inserting_add_to_device_management();
75 void before_will_be_destroyed_remove_from_device_management();
76
77 virtual void after_inserting_add_symlink_to_device_identifier_directory() = 0;
78 virtual void before_will_be_destroyed_remove_symlink_from_device_identifier_directory() = 0;
79
80 // FIXME: These methods will be eventually removed after all nodes in /sys/dev/block/ and
81 // /sys/dev/char/ are symlinks.
82 virtual void after_inserting_add_to_device_identifier_directory() = 0;
83 virtual void before_will_be_destroyed_remove_from_device_identifier_directory() = 0;
84
85private:
86 MajorNumber const m_major { 0 };
87 MinorNumber const m_minor { 0 };
88 UserID m_uid { 0 };
89 GroupID m_gid { 0 };
90
91 State m_state { State::Normal };
92
93 Spinlock<LockRank::None> m_requests_lock {};
94 DoublyLinkedList<LockRefPtr<AsyncDeviceRequest>> m_requests;
95
96protected:
97 // FIXME: This pointer will be eventually removed after all nodes in /sys/dev/block/ and
98 // /sys/dev/char/ are symlinks.
99 LockRefPtr<SysFSDeviceComponent> m_sysfs_component;
100
101 LockRefPtr<SysFSSymbolicLinkDeviceComponent> m_symlink_sysfs_component;
102 LockRefPtr<SysFSDirectory> m_sysfs_device_directory;
103};
104
105}