DWORD WINAPI InstanceThread()

in pipe-to-python-samples/main.cpp [142:253]
78 lines of code
14 McCabe index (conditional complexity)

DWORD WINAPI InstanceThread(LPVOID lpvParam)
// This routine is a thread processing function to read from and reply to a client
// via the open pipe connection passed from the main loop. Note this allows
// the main loop to continue executing, potentially creating more threads of
// of this procedure to run concurrently, depending on the number of incoming
// client connections.
{
    HANDLE hHeap = GetProcessHeap();
    TCHAR *pchRequest = (TCHAR *)HeapAlloc(hHeap, 0, BUFSIZE * sizeof(TCHAR));
    TCHAR *pchReply = (TCHAR *)HeapAlloc(hHeap, 0, FRAME_BUFSIZE);

    DWORD cbBytesRead = 0, cbReplyBytes = 0, cbWritten = 0;
    BOOL fSuccess = FALSE;
    HANDLE hPipe = NULL;

    // Do some extra error checking since the app will keep running even if this
    // thread fails.

    if (lpvParam == NULL)
    {
        printf("\nERROR - Pipe Server Failure:\n");
        printf("   InstanceThread got an unexpected NULL value in lpvParam.\n");
        printf("   InstanceThread exitting.\n");
        if (pchReply != NULL)
            HeapFree(hHeap, 0, pchReply);
        if (pchRequest != NULL)
            HeapFree(hHeap, 0, pchRequest);
        return (DWORD)-1;
    }

    if (pchRequest == NULL)
    {
        printf("\nERROR - Pipe Server Failure:\n");
        printf("   InstanceThread got an unexpected NULL heap allocation.\n");
        printf("   InstanceThread exitting.\n");
        if (pchReply != NULL)
            HeapFree(hHeap, 0, pchReply);
        return (DWORD)-1;
    }

    if (pchReply == NULL)
    {
        printf("\nERROR - Pipe Server Failure:\n");
        printf("   InstanceThread got an unexpected NULL heap allocation.\n");
        printf("   InstanceThread exitting.\n");
        if (pchRequest != NULL)
            HeapFree(hHeap, 0, pchRequest);
        return (DWORD)-1;
    }

    // Print verbose messages. In production code, this should be for debugging only.
    printf("InstanceThread created, receiving and processing messages.\n");

    // The thread's parameter is a handle to a pipe object instance.

    hPipe = (HANDLE)lpvParam;

    // Loop until done reading
    while (1)
    {
        // Read client requests from the pipe. This simplistic code only allows messages
        // up to BUFSIZE characters in length.
        fSuccess = ReadFile(hPipe,                   // handle to pipe
                            pchRequest,              // buffer to receive data
                            BUFSIZE * sizeof(TCHAR), // size of buffer
                            &cbBytesRead,            // number of bytes read
                            NULL);                   // not overlapped I/O

        if (!fSuccess || cbBytesRead == 0)
        {
            if (GetLastError() == ERROR_BROKEN_PIPE)
            {
                _tprintf(TEXT("InstanceThread: client disconnected.\n"), GetLastError());
            }
            else
            {
                _tprintf(TEXT("InstanceThread ReadFile failed, GLE=%d.\n"), GetLastError());
            }
            break;
        }

        // Process the incoming message.
        GetAnswerToRequest(pchRequest, pchReply, &cbReplyBytes);

        // Write the reply to the pipe.
        fSuccess = WriteFile(hPipe,        // handle to pipe
            pchReply,     // buffer to write from
            cbReplyBytes, // number of bytes to write
            &cbWritten,   // number of bytes written
            NULL);        // not overlapped I/O

        if (!fSuccess || cbReplyBytes != cbWritten)
        {
            _tprintf(TEXT("InstanceThread WriteFile failed, GLE=%d.\n"), GetLastError());
            break;
        }
    }

    // Flush the pipe to allow the client to read the pipe's contents
    // before disconnecting. Then disconnect the pipe, and close the
    // handle to this pipe instance.

    FlushFileBuffers(hPipe);
    DisconnectNamedPipe(hPipe);
    CloseHandle(hPipe);

    HeapFree(hHeap, 0, pchRequest);
    HeapFree(hHeap, 0, pchReply);

    printf("InstanceThread exitting.\n");
    return 1;
}