/** @file
 *
 * HGCM (Host-Guest Communication Manager):
 * HGCMObjects - Host-Guest Communication Manager objects
 */

/*
 * Copyright (C) 2006-2007 Oracle Corporation
 *
 * This file is part of VirtualBox Open Source Edition (OSE), as
 * available from http://www.virtualbox.org. This file is free software;
 * you can redistribute it and/or modify it under the terms of the GNU
 * General Public License (GPL) as published by the Free Software
 * Foundation, in version 2 as it comes in the "COPYING" file of the
 * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
 * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
 */

#define LOG_GROUP_MAIN_OVERRIDE LOG_GROUP_HGCM
#include "Logging.h"

#include "hgcm/HGCMObjects.h"

#include <string.h>

#include <VBox/err.h>


static RTCRITSECT g_critsect;

/* There are internal handles, which are not saved,
 * and client handles, which are saved.
 * They use different range of values:
 *     1..7FFFFFFF for clients,
 *     0x80000001..0xFFFFFFFF for other handles.
 */
static uint32_t volatile g_u32InternalHandleCount;
static uint32_t volatile g_u32ClientHandleCount;

static PAVLULNODECORE g_pTree;


DECLINLINE(int) hgcmObjEnter (void)
{
    return RTCritSectEnter (&g_critsect);
}

DECLINLINE(void) hgcmObjLeave (void)
{
    RTCritSectLeave (&g_critsect);
}

int hgcmObjInit (void)
{
    int rc = VINF_SUCCESS;

    LogFlow(("MAIN::hgcmObjInit\n"));

    g_u32InternalHandleCount = 0x80000000;
    g_u32ClientHandleCount = 0;
    g_pTree = NULL;

    rc = RTCritSectInit (&g_critsect);

    LogFlow(("MAIN::hgcmObjInit: rc = %Rrc\n", rc));

    return rc;
}

void hgcmObjUninit (void)
{
    if (RTCritSectIsInitialized (&g_critsect))
    {
        RTCritSectDelete (&g_critsect);
    }
}

uint32_t hgcmObjMake (HGCMObject *pObject, uint32_t u32HandleIn)
{
    int handle = 0;

    LogFlow(("MAIN::hgcmObjGenerateHandle: pObject %p\n", pObject));

    int rc = hgcmObjEnter ();

    if (RT_SUCCESS(rc))
    {
        ObjectAVLCore *pCore = &pObject->m_core;

        /* Generate a new handle value. */

        uint32_t volatile *pu32HandleCountSource = pObject->Type () == HGCMOBJ_CLIENT?
                                                       &g_u32ClientHandleCount:
                                                       &g_u32InternalHandleCount;

        uint32_t u32Start = *pu32HandleCountSource;

        for (;;)
        {
            uint32_t Key;

            if (u32HandleIn == 0)
            {
                Key = ASMAtomicIncU32 (pu32HandleCountSource);

                if (Key == u32Start)
                {
                    /* Rollover. Something is wrong. */
                    AssertReleaseFailed ();
                    break;
                }

                /* 0 and 0x80000000 are not valid handles. */
                if ((Key & 0x7FFFFFFF) == 0)
                {
                    /* Over the invalid value, reinitialize the source. */
                    *pu32HandleCountSource = pObject->Type () == HGCMOBJ_CLIENT?
                                                 0:
                                                 0x80000000;
                    continue;
                }
            }
            else
            {
                Key = u32HandleIn;
            }

            /* Insert object to AVL tree. */
            pCore->AvlCore.Key = Key;

            bool bRC = RTAvlULInsert(&g_pTree, &pCore->AvlCore);

            /* Could not insert a handle. */
            if (!bRC)
            {
                if (u32HandleIn == 0)
                {
                    /* Try another generated handle. */
                    continue;
                }
                else
                {
                    /* Could not use the specified handle. */
                    break;
                }
            }

            /* Initialize backlink. */
            pCore->pSelf = pObject;

            /* Reference the object for time while it resides in the tree. */
            pObject->Reference ();

            /* Store returned handle. */
            handle = Key;

            Log(("Object key inserted 0x%08X\n", Key));

            break;
        }

        hgcmObjLeave ();
    }
    else
    {
        AssertReleaseMsgFailed (("MAIN::hgcmObjGenerateHandle: Failed to acquire object pool semaphore"));
    }

    LogFlow(("MAIN::hgcmObjGenerateHandle: handle = 0x%08X, rc = %Rrc, return void\n", handle, rc));

    return handle;
}

uint32_t hgcmObjGenerateHandle (HGCMObject *pObject)
{
    return hgcmObjMake (pObject, 0);
}

uint32_t hgcmObjAssignHandle (HGCMObject *pObject, uint32_t u32Handle)
{
    return hgcmObjMake (pObject, u32Handle);
}

void hgcmObjDeleteHandle (uint32_t handle)
{
    int rc = VINF_SUCCESS;

    LogFlow(("MAIN::hgcmObjDeleteHandle: handle 0x%08X\n", handle));

    if (handle)
    {
        rc = hgcmObjEnter ();

        if (RT_SUCCESS(rc))
        {
            ObjectAVLCore *pCore = (ObjectAVLCore *)RTAvlULRemove (&g_pTree, handle);

            if (pCore)
            {
                AssertRelease(pCore->pSelf);

                pCore->pSelf->Dereference ();
            }

            hgcmObjLeave ();
        }
        else
        {
            AssertReleaseMsgFailed (("Failed to acquire object pool semaphore, rc = %Rrc", rc));
        }
    }

    LogFlow(("MAIN::hgcmObjDeleteHandle: rc = %Rrc, return void\n", rc));

    return;
}

HGCMObject *hgcmObjReference (uint32_t handle, HGCMOBJ_TYPE enmObjType)
{
    LogFlow(("MAIN::hgcmObjReference: handle 0x%08X\n", handle));

    HGCMObject *pObject = NULL;

    if ((handle & 0x7FFFFFFF) == 0)
    {
        return pObject;
    }

    int rc = hgcmObjEnter ();

    if (RT_SUCCESS(rc))
    {
        ObjectAVLCore *pCore = (ObjectAVLCore *)RTAvlULGet (&g_pTree, handle);

        Assert(!pCore || (pCore->pSelf && pCore->pSelf->Type() == enmObjType));
        if (    pCore
            &&  pCore->pSelf
            &&  pCore->pSelf->Type() == enmObjType)
        {
            pObject = pCore->pSelf;

            AssertRelease(pObject);

            pObject->Reference ();
        }

        hgcmObjLeave ();
    }
    else
    {
        AssertReleaseMsgFailed (("Failed to acquire object pool semaphore, rc = %Rrc", rc));
    }

    LogFlow(("MAIN::hgcmObjReference: return pObject %p\n", pObject));

    return pObject;
}

void hgcmObjDereference (HGCMObject *pObject)
{
    LogFlow(("MAIN::hgcmObjDereference: pObject %p\n", pObject));

    AssertRelease(pObject);

    pObject->Dereference ();

    LogFlow(("MAIN::hgcmObjDereference: return\n"));
}

uint32_t hgcmObjQueryHandleCount ()
{
    return g_u32ClientHandleCount;
}

void hgcmObjSetHandleCount (uint32_t u32ClientHandleCount)
{
    Assert(g_u32ClientHandleCount <= u32ClientHandleCount);

    int rc = hgcmObjEnter ();

    if (RT_SUCCESS(rc))
    {
        if (g_u32ClientHandleCount <= u32ClientHandleCount)
            g_u32ClientHandleCount = u32ClientHandleCount;
        hgcmObjLeave ();
   }
}