Dictionary ReadTdhMap()

in Source/Tx.Windows/EtwTdh/EtwTdhEventInfo.cs [193:234]
35 lines of code
4 McCabe index (conditional complexity)

        Dictionary<uint, string> ReadTdhMap(string mapName, ref EtwNativeEvent e)
        {
            IntPtr pMapName = Marshal.StringToBSTR(mapName);

            int bufferSize = 0;
            int status = EtwNativeMethods.TdhGetEventMapInformation(
                ref *e.record,
                pMapName,
                IntPtr.Zero, ref bufferSize);

            if (122 != status) // ERROR_INSUFFICIENT_BUFFER
            {
                throw new Exception("Unexpected TDH status " + status);
            }

            var mybuffer = Marshal.AllocHGlobal(bufferSize);
            status = EtwNativeMethods.TdhGetEventMapInformation(
                ref *e.record,
                pMapName,
                mybuffer, ref bufferSize);

            if (status != 0)
            {
                throw new Exception("TDH status " + status);
            }

            EVENT_MAP_INFO* mapInfo = (EVENT_MAP_INFO*)mybuffer;
            byte* startMap = (byte*)mapInfo;
            var name1 = CopyString(startMap, mapInfo->NameOffset);
            byte* endMap = startMap + sizeof(EVENT_MAP_INFO);

            var map = new Dictionary<uint, string>();
            for (int i = 0; i < mapInfo->EntryCount; i++)
            {
                EVENT_MAP_ENTRY* mapEntry = (EVENT_MAP_ENTRY*)endMap + i;
                uint value = mapEntry->Value;
                string name = CopyString(startMap, mapEntry->OutputOffset);
                map.Add(value, name);
            }

            return map;
        }