Memory allocation problem

[Machado]

Please help me how to use memcpy in the following situation.
When I run the following code, I am getting Segmentation error due to memcpy. I can see some problem with my Setdata function. how do I correct it.

struct Packet_t
{   
    int  mType;   
    int  mUnit;   
    unsigned long mLength;
    char   mMessage[1];
} __attribute__((__packed__));          // packet is packed...


class PacketAccessor
{
   private:

    Packet_t mData;

   public: 
     //Default Constructor
     PacketAccessor(): mData()
     {
     }      
                 
    //Default Destructor
    ~DistributionPacketAccessor()
    {    

    }    

    //--------------------------------------------------------

    //! Get accessor functions
    //--------------------------------------------------------

    int GetType() const                { return mData.mType; };
    int GetUnit() const                { return mData.mUnit; };
    unsigned long GetLength() const    { return ntohs(mData.mLength); };
    char *GetData()                    { return mData.mMessage;}

    //--------------------------------------------------------
    //! Set accessor functions
    //--------------------------------------------------------
    void SetTypeIdentifier(const int type)     { mData.mType = type; };
    void SetUnit(const int unit)               { mData.mUnit = unit; };
    void SetLength(const int dataLength)       { mData.mLength = htons(dataLength); };                void SetData(char * data, unsigned long length)
    {        memcpy(mData.mMessage, data, length);    }    

}; 

[prog-bman]

Maybe you meant length + 1 if you are working with c-style strings.