summaryrefslogtreecommitdiffstats
path: root/src/core/hle/kernel/handle_table.h
blob: d5718884458b16fb5e4075e8250b96ea710c3753 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
// Copyright 2014 Citra Emulator Project
// Licensed under GPLv2 or any later version
// Refer to the license.txt file included.

#pragma once

#include <array>
#include <cstddef>
#include <memory>

#include "common/common_types.h"
#include "core/hle/kernel/k_auto_object.h"
#include "core/hle/kernel/kernel.h"
#include "core/hle/kernel/object.h"
#include "core/hle/result.h"

namespace Kernel {

class KernelCore;

enum KernelHandle : Handle {
    InvalidHandle = 0,
    CurrentThread = 0xFFFF8000,
    CurrentProcess = 0xFFFF8001,
};

/**
 * This class allows the creation of Handles, which are references to objects that can be tested
 * for validity and looked up. Here they are used to pass references to kernel objects to/from the
 * emulated process. it has been designed so that it follows the same handle format and has
 * approximately the same restrictions as the handle manager in the CTR-OS.
 *
 * Handles contain two sub-fields: a slot index (bits 31:15) and a generation value (bits 14:0).
 * The slot index is used to index into the arrays in this class to access the data corresponding
 * to the Handle.
 *
 * To prevent accidental use of a freed Handle whose slot has already been reused, a global counter
 * is kept and incremented every time a Handle is created. This is the Handle's "generation". The
 * value of the counter is stored into the Handle as well as in the handle table (in the
 * "generations" array). When looking up a handle, the Handle's generation must match with the
 * value stored on the class, otherwise the Handle is considered invalid.
 *
 * To find free slots when allocating a Handle without needing to scan the entire object array, the
 * generations field of unallocated slots is re-purposed as a linked list of indices to free slots.
 * When a Handle is created, an index is popped off the list and used for the new Handle. When it
 * is destroyed, it is again pushed onto the list to be re-used by the next allocation. It is
 * likely that this allocation strategy differs from the one used in CTR-OS, but this hasn't been
 * verified and isn't likely to cause any problems.
 */
class HandleTable final : NonCopyable {
public:
    /// This is the maximum limit of handles allowed per process in Horizon
    static constexpr std::size_t MAX_COUNT = 1024;

    explicit HandleTable(KernelCore& kernel);
    ~HandleTable();

    /**
     * Sets the number of handles that may be in use at one time
     * for this handle table.
     *
     * @param handle_table_size The desired size to limit the handle table to.
     *
     * @returns an error code indicating if initialization was successful.
     *          If initialization was not successful, then ERR_OUT_OF_MEMORY
     *          will be returned.
     *
     * @pre handle_table_size must be within the range [0, 1024]
     */
    ResultCode SetSize(s32 handle_table_size);

    /**
     * Allocates a handle for the given object.
     * @return The created Handle or one of the following errors:
     *           - `ERR_HANDLE_TABLE_FULL`: the maximum number of handles has been exceeded.
     */
    ResultVal<Handle> Create(Object* obj);

    /**
     * Returns a new handle that points to the same object as the passed in handle.
     * @return The duplicated Handle or one of the following errors:
     *           - `ERR_INVALID_HANDLE`: an invalid handle was passed in.
     *           - Any errors returned by `Create()`.
     */
    ResultVal<Handle> Duplicate(Handle handle);

    /**
     * Closes a handle, removing it from the table and decreasing the object's ref-count.
     * @return `RESULT_SUCCESS` or one of the following errors:
     *           - `ERR_INVALID_HANDLE`: an invalid handle was passed in.
     */
    bool Remove(Handle handle);

    /// Checks if a handle is valid and points to an existing object.
    bool IsValid(Handle handle) const;

    /**
     * Looks up a handle.
     * @return Pointer to the looked-up object, or `nullptr` if the handle is not valid.
     */
    Object* GetGeneric(Handle handle) const;

    /**
     * Looks up a handle while verifying its type.
     * @return Pointer to the looked-up object, or `nullptr` if the handle is not valid or its
     *         type differs from the requested one.
     */
    template <class T>
    T* Get(Handle handle) const {
        return DynamicObjectCast<T>(GetGeneric(handle));
    }

    template <typename T = KAutoObject>
    KScopedAutoObject<T> GetObject(Handle handle) const {
        if (handle == CurrentThread) {
            return kernel.CurrentScheduler()->GetCurrentThread()->DynamicCast<T*>();
        } else if (handle == CurrentProcess) {
            return kernel.CurrentProcess()->DynamicCast<T*>();
        }

        if (!IsValid(handle)) {
            return nullptr;
        }

        auto* obj = objects_new[static_cast<u16>(handle >> 15)];
        return obj->DynamicCast<T*>();
    }

    template <typename T = KAutoObject>
    KScopedAutoObject<T> GetObjectWithoutPseudoHandle(Handle handle) const {
        if (!IsValid(handle)) {
            return nullptr;
        }
        auto* obj = objects_new[static_cast<u16>(handle >> 15)];
        return obj->DynamicCast<T*>();
    }

    /// Closes all handles held in this table.
    void Clear();

    // NEW IMPL

    template <typename T>
    ResultCode Add(Handle* out_handle, T* obj) {
        static_assert(std::is_base_of<KAutoObject, T>::value);
        return this->Add(out_handle, obj, obj->GetTypeObj().GetClassToken());
    }

    ResultCode Add(Handle* out_handle, KAutoObject* obj, u16 type);

private:
    /// Stores the Object referenced by the handle or null if the slot is empty.
    std::array<std::shared_ptr<Object>, MAX_COUNT> objects;
    std::array<KAutoObject*, MAX_COUNT> objects_new{};

    /**
     * The value of `next_generation` when the handle was created, used to check for validity. For
     * empty slots, contains the index of the next free slot in the list.
     */
    std::array<u16, MAX_COUNT> generations;

    /**
     * The limited size of the handle table. This can be specified by process
     * capabilities in order to restrict the overall number of handles that
     * can be created in a process instance
     */
    u16 table_size = static_cast<u16>(MAX_COUNT);

    /**
     * Global counter of the number of created handles. Stored in `generations` when a handle is
     * created, and wraps around to 1 when it hits 0x8000.
     */
    u16 next_generation = 1;

    /// Head of the free slots linked list.
    u16 next_free_slot = 0;

    /// Underlying kernel instance that this handle table operates under.
    KernelCore& kernel;
};

} // namespace Kernel