ob_x.h

ReactOS是一些高手根据Windows XP的内核编写出的类XP。内核实现机理和API函数调用几乎相同。甚至可以兼容XP的程序。喜欢研究系统内核的人可以看一看。

/*
* PROJECT:         ReactOS Kernel
* LICENSE:         GPL - See COPYING in the top level directory
* FILE:            ntoskrnl/include/ob_x.h
* PURPOSE:         Intenral Inlined Functions for the Object Manager
* PROGRAMMERS:     Alex Ionescu ([e-mail])
*/

#include "ex.h"

#define OBP_LOCK_STATE_PRE_ACQUISITION_EXCLUSIVE    0xAAAA1234
#define OBP_LOCK_STATE_PRE_ACQUISITION_SHARED       0xBBBB1234
#define OBP_LOCK_STATE_POST_ACQUISITION_EXCLUSIVE   0xCCCC1234
#define OBP_LOCK_STATE_POST_ACQUISITION_SHARED      0xDDDD1234
#define OBP_LOCK_STATE_RELEASED                     0xEEEE1234
#define OBP_LOCK_STATE_INITIALIZED                  0xFFFF1234

POBJECT_HEADER_NAME_INFO
FORCEINLINE
ObpAcquireNameInformation(IN POBJECT_HEADER ObjectHeader)
{
    POBJECT_HEADER_NAME_INFO ObjectNameInfo;
    ULONG NewValue, References;

    /* Make sure we have name information at all */
    ObjectNameInfo = OBJECT_HEADER_TO_NAME_INFO(ObjectHeader);
    if (!ObjectNameInfo) return NULL;

    /* Get the number of references */
    References = ObjectNameInfo->QueryReferences;
    for (;;)
    {
        /* Check if the count is 0 and fail if so */
        if (!References) return NULL;

        /* Increment the number of references */
        NewValue = InterlockedCompareExchange((PLONG)&ObjectNameInfo->
                                              QueryReferences,
                                              References + 1,
                                              References);
        if (NewValue == References) break;

        /* We failed, try again */
        References = NewValue;
    }

    /* Check for magic flag */
    if (ObjectNameInfo->QueryReferences & 0x80000000)
    {
        /* FIXME: Unhandled*/
        DbgPrint("OB: Unhandled path\n");
        KEBUGCHECK(0);
    }

    /* Return the name information */
    return ObjectNameInfo;
}

VOID
FORCEINLINE
ObpReleaseNameInformation(IN POBJECT_HEADER_NAME_INFO HeaderNameInfo)
{
    POBJECT_DIRECTORY Directory;

    /* Bail out if there's no info at all */
    if (!HeaderNameInfo) return;

    /* Remove a query reference and check if it was the last one */
    if (!InterlockedDecrement((PLONG)&HeaderNameInfo->QueryReferences))
    {
        /* Check if we have a name */
        if (HeaderNameInfo->Name.Buffer)
        {
            /* We can get rid of the object name now */
            ExFreePool(HeaderNameInfo->Name.Buffer);
            RtlInitEmptyUnicodeString(&HeaderNameInfo->Name, NULL, 0);
        }

        /* Check if the object has a directory associated to it */
        Directory = HeaderNameInfo->Directory;
        if (Directory)
        {
            /* Delete the directory */
            HeaderNameInfo->Directory = NULL;
            ObDereferenceObjectDeferDelete(Directory);
        }
    }
}

VOID
FORCEINLINE
ObpAcquireDirectoryLockShared(IN POBJECT_DIRECTORY Directory,
                               IN POBP_LOOKUP_CONTEXT Context)
{
    /* It's not, set lock flag */
    Context->LockStateSignature = OBP_LOCK_STATE_PRE_ACQUISITION_SHARED;

    /* Lock it */
    KeEnterCriticalRegion();
    ExAcquirePushLockShared(&Directory->Lock);

    /* Update lock flag */
    Context->LockStateSignature = OBP_LOCK_STATE_POST_ACQUISITION_SHARED;
}

VOID
FORCEINLINE
ObpAcquireDirectoryLockExclusive(IN POBJECT_DIRECTORY Directory,
                                  IN POBP_LOOKUP_CONTEXT Context)
{
    /* Update lock flag */
    Context->LockStateSignature = OBP_LOCK_STATE_PRE_ACQUISITION_EXCLUSIVE;

    /* Acquire an exclusive directory lock */
    KeEnterCriticalRegion();
    ExAcquirePushLockExclusive(&Directory->Lock);

    /* Set the directory */
    Context->Directory = Directory;

    /* Update lock settings */
    Context->LockStateSignature = OBP_LOCK_STATE_POST_ACQUISITION_EXCLUSIVE;
    Context->DirectoryLocked = TRUE;
}

VOID
FORCEINLINE
ObpReleaseDirectoryLock(IN POBJECT_DIRECTORY Directory,
                         IN POBP_LOOKUP_CONTEXT Context)
{
    /* Release the lock */
    ExReleasePushLock(&Directory->Lock);
    Context->LockStateSignature = OBP_LOCK_STATE_RELEASED;
    KeLeaveCriticalRegion();
}

VOID
FORCEINLINE
ObpInitializeDirectoryLookup(IN POBP_LOOKUP_CONTEXT Context)
{
    /* Initialize a null context */
    Context->Object = NULL;
    Context->Directory = NULL;
    Context->DirectoryLocked = FALSE;
    Context->LockStateSignature = OBP_LOCK_STATE_INITIALIZED;
}

VOID
FORCEINLINE
ObpReleaseLookupContextObject(IN POBP_LOOKUP_CONTEXT Context)
{
    POBJECT_HEADER ObjectHeader;
    POBJECT_HEADER_NAME_INFO HeaderNameInfo;

    /* Check if we had found an object */
    if (Context->Object)
    {
        /* Get the object name information */
        ObjectHeader = OBJECT_TO_OBJECT_HEADER(Context->Object);
        HeaderNameInfo = OBJECT_HEADER_TO_NAME_INFO(ObjectHeader);

        /* release the name information */
        ObpReleaseNameInformation(HeaderNameInfo);

        /* Dereference the object */
        ObDereferenceObject(Context->Object);
        Context->Object = NULL;
    }
}

VOID
FORCEINLINE
ObpCleanupDirectoryLookup(IN POBP_LOOKUP_CONTEXT Context)
{
    /* Check if we came back with the directory locked */
    if (Context->DirectoryLocked)
    {
        /* Release the lock */
        ObpReleaseDirectoryLock(Context->Directory, Context);
        Context->Directory = NULL;
        Context->DirectoryLocked = FALSE;
    }

    /* Clear the context  */
    ObpReleaseLookupContextObject(Context);
}

VOID
FORCEINLINE
ObpEnterObjectTypeMutex(IN POBJECT_TYPE ObjectType)
{
    /* Sanity check */
    ASSERT(KeGetCurrentIrql() <= APC_LEVEL);

    /* Enter a critical region and acquire the resource */
    KeEnterCriticalRegion();
    ExAcquireResourceExclusiveLite(&ObjectType->Mutex, TRUE);
}

VOID
FORCEINLINE
ObpLeaveObjectTypeMutex(IN POBJECT_TYPE ObjectType)
{
    /* Enter a critical region and acquire the resource */
    ExReleaseResourceLite(&ObjectType->Mutex);
    KeLeaveCriticalRegion();

    /* Sanity check */
    ASSERT(KeGetCurrentIrql() <= APC_LEVEL);
}

VOID
FORCEINLINE
ObpReleaseCapturedAttributes(IN POBJECT_CREATE_INFORMATION ObjectCreateInfo)
{
    /* Check if we have a security descriptor */
    if (ObjectCreateInfo->SecurityDescriptor)
    {
        /* Release it */
        SeReleaseSecurityDescriptor(ObjectCreateInfo->SecurityDescriptor,
                                    ObjectCreateInfo->ProbeMode,
                                    TRUE);
        ObjectCreateInfo->SecurityDescriptor = NULL;
    }
}

PVOID
FORCEINLINE
ObpAllocateCapturedAttributes(IN PP_NPAGED_LOOKASIDE_NUMBER Type)
{
    PVOID Buffer;
    PNPAGED_LOOKASIDE_LIST List;
    PKPRCB Prcb = KeGetCurrentPrcb();

    /* Get the P list first */
    List = (PNPAGED_LOOKASIDE_LIST)Prcb->PPLookasideList[Type].P;

    /* Attempt allocation */
    List->L.TotalAllocates++;
    Buffer = (PVOID)InterlockedPopEntrySList(&List->L.ListHead);
    if (!Buffer)
    {
        /* Let the balancer know that the P list failed */
        List->L.AllocateMisses++;

        /* Try the L List */
        List = (PNPAGED_LOOKASIDE_LIST)Prcb->PPLookasideList[Type].L;
        List->L.TotalAllocates++;
        Buffer = (PVOID)InterlockedPopEntrySList(&List->L.ListHead);
        if (!Buffer)
        {
            /* Let the balancer know the L list failed too */
            List->L.AllocateMisses++;

            /* Allocate it */
            Buffer = List->L.Allocate(List->L.Type, List->L.Size, List->L.Tag);
        }
    }

    /* Return buffer */
    return Buffer;
}

VOID
FORCEINLINE
ObpFreeCapturedAttributes(IN PVOID Buffer,
                          IN PP_NPAGED_LOOKASIDE_NUMBER Type)
{
    PNPAGED_LOOKASIDE_LIST List;
    PKPRCB Prcb = KeGetCurrentPrcb();

    /* Use the P List */
    List = (PNPAGED_LOOKASIDE_LIST)Prcb->PPLookasideList[Type].P;
    List->L.TotalFrees++;

    /* Check if the Free was within the Depth or not */
    if (ExQueryDepthSList(&List->L.ListHead) >= List->L.Depth)
    {
        /* Let the balancer know */
        List->L.FreeMisses++;

        /* Use the L List */
        List = (PNPAGED_LOOKASIDE_LIST)Prcb->PPLookasideList[Type].L;
        List->L.TotalFrees++;

        /* Check if the Free was within the Depth or not */
        if (ExQueryDepthSList(&List->L.ListHead) >= List->L.Depth)
        {
            /* All lists failed, use the pool */
            List->L.FreeMisses++;
            List->L.Free(Buffer);
        }
    }
    else
    {
        /* The free was within the Depth */
        InterlockedPushEntrySList(&List->L.ListHead,
                                  (PSINGLE_LIST_ENTRY)Buffer);
    }
}

VOID
FORCEINLINE
ObpFreeAndReleaseCapturedAttributes(IN POBJECT_CREATE_INFORMATION ObjectCreateInfo)
{
    /* First release the attributes, then free them from the lookaside list */
    ObpReleaseCapturedAttributes(ObjectCreateInfo);
    ObpFreeCapturedAttributes(ObjectCreateInfo, LookasideCreateInfoList);
}

#if DBG
VOID
FORCEINLINE
ObpCalloutStart(IN PKIRQL CalloutIrql)
{
    /* Save the callout IRQL */
    *CalloutIrql = KeGetCurrentIrql();
}

VOID
FORCEINLINE
ObpCalloutEnd(IN KIRQL CalloutIrql,
              IN PCHAR Procedure,
              IN POBJECT_TYPE ObjectType,
              IN PVOID Object)
{
    /* Detect IRQL change */
    if (CalloutIrql != KeGetCurrentIrql())
    {
        /* Print error */
        DbgPrint("OB: ObjectType: %wZ  Procedure: %s  Object: %08x\n",
                 &ObjectType->Name, Procedure, Object);
        DbgPrint("    Returned at %x IRQL, but was called at %x IRQL\n",
                 KeGetCurrentIrql(), CalloutIrql);
        DbgBreakPoint();
    }
}
#else
VOID
FORCEINLINE
ObpCalloutStart(IN PKIRQL CalloutIrql)
{
    /* No-op */
    UNREFERENCED_PARAMETER(CalloutIrql);
}

VOID
FORCEINLINE
ObpCalloutEnd(IN KIRQL CalloutIrql,
              IN PCHAR Procedure,
              IN POBJECT_TYPE ObjectType,
              IN PVOID Object)
{
    UNREFERENCED_PARAMETER(CalloutIrql);
}
#endif