/*
 * Process Hacker -
 *   internal object manager
 *
 * Copyright (C) 2009-2016 wj32
 *
 * This file is part of Process Hacker.
 *
 * Process Hacker is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Process Hacker is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Process Hacker.  If not, see <http://www.gnu.org/licenses/>.
 */

#ifndef _PH_REFP_H
#define _PH_REFP_H

#define PH_OBJECT_TYPE_TABLE_SIZE 256

/** The object was allocated from the small free list. */
#define PH_OBJECT_FROM_SMALL_FREE_LIST 0x1
/** The object was allocated from the type free list. */
#define PH_OBJECT_FROM_TYPE_FREE_LIST 0x2

/**
 * The object header contains object manager information including the reference count of an object
 * and its type.
 */
typedef struct _PH_OBJECT_HEADER
{
    union
    {
        struct
        {
            USHORT TypeIndex;
            UCHAR Flags;
            UCHAR Reserved1;
#ifdef _WIN64
            ULONG Reserved2;
#endif
            union
            {
                LONG RefCount;
                struct
                {
                    LONG SavedTypeIndex : 16;
                    LONG SavedFlags : 8;
                    LONG Reserved : 7;
                    LONG DeferDelete : 1; // MUST be the high bit, so that RefCount < 0 when deferring delete
                };
            };
#ifdef _WIN64
            ULONG Reserved3;
#endif
        };
        SLIST_ENTRY DeferDeleteListEntry;
    };

#ifdef DEBUG
    PVOID StackBackTrace[16];
    LIST_ENTRY ObjectListEntry;
#endif

    /**
     * The body of the object. For use by the \ref PhObjectToObjectHeader and
     * \ref PhObjectHeaderToObject macros.
     */
    QUAD_PTR Body;
} PH_OBJECT_HEADER, *PPH_OBJECT_HEADER;

#ifndef DEBUG
#ifdef _WIN64
C_ASSERT(FIELD_OFFSET(PH_OBJECT_HEADER, TypeIndex) == 0x0);
C_ASSERT(FIELD_OFFSET(PH_OBJECT_HEADER, Flags) == 0x2);
C_ASSERT(FIELD_OFFSET(PH_OBJECT_HEADER, Reserved1) == 0x3);
C_ASSERT(FIELD_OFFSET(PH_OBJECT_HEADER, Reserved2) == 0x4);
C_ASSERT(FIELD_OFFSET(PH_OBJECT_HEADER, RefCount) == 0x8);
C_ASSERT(FIELD_OFFSET(PH_OBJECT_HEADER, Reserved3) == 0xc);
C_ASSERT(FIELD_OFFSET(PH_OBJECT_HEADER, DeferDeleteListEntry) == 0x0);
C_ASSERT(FIELD_OFFSET(PH_OBJECT_HEADER, Body) == 0x10);
#else
C_ASSERT(FIELD_OFFSET(PH_OBJECT_HEADER, TypeIndex) == 0x0);
C_ASSERT(FIELD_OFFSET(PH_OBJECT_HEADER, Flags) == 0x2);
C_ASSERT(FIELD_OFFSET(PH_OBJECT_HEADER, Reserved1) == 0x3);
C_ASSERT(FIELD_OFFSET(PH_OBJECT_HEADER, RefCount) == 0x4);
C_ASSERT(FIELD_OFFSET(PH_OBJECT_HEADER, DeferDeleteListEntry) == 0x0);
C_ASSERT(FIELD_OFFSET(PH_OBJECT_HEADER, Body) == 0x8);
#endif
#endif

/**
 * Gets a pointer to the object header for an object.
 *
 * \param Object A pointer to an object.
 *
 * \return A pointer to the object header of the object.
 */
#define PhObjectToObjectHeader(Object) ((PPH_OBJECT_HEADER)CONTAINING_RECORD((PCHAR)(Object), PH_OBJECT_HEADER, Body))

/**
 * Gets a pointer to an object from an object header.
 *
 * \param ObjectHeader A pointer to an object header.
 *
 * \return A pointer to an object.
 */
#define PhObjectHeaderToObject(ObjectHeader) ((PVOID)&((PPH_OBJECT_HEADER)(ObjectHeader))->Body)

/**
 * Calculates the total size to allocate for an object.
 *
 * \param Size The size of the object to allocate.
 *
 * \return The new size, including space for the object header.
 */
#define PhAddObjectHeaderSize(Size) ((Size) + FIELD_OFFSET(PH_OBJECT_HEADER, Body))

/** An object type specifies a kind of object and its delete procedure. */
typedef struct _PH_OBJECT_TYPE
{
    /** The flags that were used to create the object type. */
    USHORT Flags;
    UCHAR TypeIndex;
    UCHAR Reserved;
    /** The total number of objects of this type that are alive. */
    ULONG NumberOfObjects;
    /** An optional procedure called when objects of this type are freed. */
    PPH_TYPE_DELETE_PROCEDURE DeleteProcedure;
    /** The name of the type. */
    PWSTR Name;
    /** A free list to use when allocating for this type. */
    PH_FREE_LIST FreeList;
} PH_OBJECT_TYPE, *PPH_OBJECT_TYPE;

/**
 * Increments a reference count, but will never increment from a nonpositive value to 1.
 *
 * \param RefCount A pointer to a reference count.
 */
FORCEINLINE
BOOLEAN
PhpInterlockedIncrementSafe(
    _Inout_ PLONG RefCount
    )
{
    /* Here we will attempt to increment the reference count, making sure that it is positive. */
    return _InterlockedIncrementPositive(RefCount);
}

PPH_OBJECT_HEADER PhpAllocateObject(
    _In_ PPH_OBJECT_TYPE ObjectType,
    _In_ SIZE_T ObjectSize
    );

VOID PhpFreeObject(
    _In_ PPH_OBJECT_HEADER ObjectHeader
    );

VOID PhpDeferDeleteObject(
    _In_ PPH_OBJECT_HEADER ObjectHeader
    );

NTSTATUS PhpDeferDeleteObjectRoutine(
    _In_ PVOID Parameter
    );

#endif