CODEWITHSUNDEEP
c++wdk
Joe.wang
Joe.wang

Reputation: 11791

Why RtlCopyMemory failed

All, I was trying to use RtlCopyMemory to duplicate a structure instance, But seems it didn't successfully copy the instance before the callback returns. I didn't know if I missed something, Please help to review the below code. Thanks.

#define RtlZeroMemory(Destination,Length) memset((Destination),0,(Length))
#define RtlCopyMemory(Destination,Source,Length) memcpy((Destination),(Source),(Length))

typedef struct _FLT_RELATED_OBJECTS {

    USHORT CONST Size;
    USHORT CONST TransactionContext;            //TxF mini-version
    PFLT_FILTER CONST Filter;
    PFLT_VOLUME CONST Volume;
    PFLT_INSTANCE CONST Instance;
    PFILE_OBJECT CONST FileObject;
    PKTRANSACTION CONST Transaction;

} FLT_RELATED_OBJECTS, *PFLT_RELATED_OBJECTS;

FLT_POSTOP_CALLBACK_STATUS
CreateBackUpFile_WhenPostCreatedCallback (
    _Inout_ PFLT_CALLBACK_DATA Data,
    _In_ PCFLT_RELATED_OBJECTS FltObjects,
    _In_ PVOID CompletionContext,
    _In_ FLT_POST_OPERATION_FLAGS Flags
    )
{
   PFLT_RELATED_OBJECTS copiedRelatedObj;
   ...
   RtlZeroMemory(&copiedRelatedObj, FltObjects->Size);
   KdBreakPoint();
   RtlCopyMemory(&copiedRelatedObj,FltObjects,FltObjects->Size);
   DbgPrint("The file name in the FltObjects is : %s\n",FltObjects->FileObject->FileName);
   DbgPrint("The file name in the Duplicated FltObjects is : %s\n",copiedRelatedObj->FileObject->FileName);
   ...
}

Upvotes: 0

Views: 1086

Answers (2)

Ivan
Ivan

Reputation: 2057

RtlZeroMemory requires pointer to a memory block as its first argument. But you give it pointer to pointer ( as PFLT_RELATED_OBJECTS is already a pointer ). Use

FLT_RELATED_OBJECTS copiedRelatedObj;

Upvotes: 1

Hans Passant
Hans Passant

Reputation: 942109

   PFLT_RELATED_OBJECTS copiedRelatedObj;

The copiedRelatedObj variable is a pointer. It is not initialized. Yell a bit invisible Microsoft C programmers for that dreadful habit of declaring pointer types. Then remove the P. Fix:

   FLT_RELATED_OBJECTS copiedRelatedObj;

Upvotes: 1

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