comm_ioctl.c

 
#include <winpr/config.h>
 
#include <winpr/assert.h>
#include <errno.h>
 
#include <winpr/wlog.h>
 
#include "comm.h"
#include "comm_ioctl.h"
#include "comm_serial_sys.h"
#include "comm_sercx_sys.h"
#include "comm_sercx2_sys.h"
 
static const char* comm_ioctl_modem_status_string(ULONG status, char* buffer, size_t size);
 
/* NB: MS-RDPESP's recommendation:
 *
 * <2> Section 3.2.5.1.6: Windows Implementations use IOCTL constants
 * for IoControlCode values.  The content and values of the IOCTLs are
 * opaque to the protocol. On the server side, the data contained in
 * an IOCTL is simply packaged and sent to the client side. For
 * maximum compatibility between the different versions of the Windows
 * operating system, the client implementation only singles out
 * critical IOCTLs and invokes the applicable Win32 port API. The
 * other IOCTLS are passed directly to the client-side driver, and the
 * processing of this value depends on the drivers installed on the
 * client side. The values and parameters for these IOCTLS can be
 * found in [MSFT-W2KDDK] Volume 2, Part 2—Serial and Parallel
 * Drivers, and in [MSDN-PORTS].
 */
static BOOL s_CommDeviceIoControl(HANDLE hDevice, DWORD dwIoControlCode, LPVOID lpInBuffer,
                                  DWORD nInBufferSize, LPVOID lpOutBuffer, DWORD nOutBufferSize,
                                  LPDWORD lpBytesReturned, LPOVERLAPPED lpOverlapped)
{
  char buffer[128] = WINPR_C_ARRAY_INIT;
  WINPR_COMM* pComm = (WINPR_COMM*)hDevice;
  const SERIAL_DRIVER* pServerSerialDriver = nullptr;
 
  if (!CommIsHandleValid(hDevice))
    return FALSE;
 
  if (lpOverlapped)
  {
    SetLastError(ERROR_NOT_SUPPORTED);
    return FALSE;
  }
 
  if (lpBytesReturned == nullptr)
  {
    SetLastError(
        ERROR_INVALID_PARAMETER); /* since we doesn't support lpOverlapped != nullptr */
    return FALSE;
  }
 
  /* clear any previous last error */
  SetLastError(ERROR_SUCCESS);
 
  *lpBytesReturned = 0; /* will be adjusted if required ... */
 
  CommLog_Print(WLOG_DEBUG, "CommDeviceIoControl: IoControlCode: %s [0x%08" PRIx32 "]",
                _comm_serial_ioctl_name(dwIoControlCode), dwIoControlCode);
 
  /* remoteSerialDriver to be use ...
   *
   * FIXME: might prefer to use an automatic rather than static structure
   */
  switch (pComm->serverSerialDriverId)
  {
    case SerialDriverSerialSys:
      pServerSerialDriver = SerialSys_s();
      break;
 
    case SerialDriverSerCxSys:
      pServerSerialDriver = SerCxSys_s();
      break;
 
    case SerialDriverSerCx2Sys:
      pServerSerialDriver = SerCx2Sys_s();
      break;
 
    case SerialDriverUnknown:
    default:
      CommLog_Print(WLOG_DEBUG, "Unknown remote serial driver (%u), using SerCx2.sys",
                    pComm->serverSerialDriverId);
      pServerSerialDriver = SerCx2Sys_s();
      break;
  }
 
  WINPR_ASSERT(pServerSerialDriver != nullptr);
 
  switch (dwIoControlCode)
  {
    case IOCTL_USBPRINT_GET_1284_ID:
    {
      /* FIXME:
       * http://msdn.microsoft.com/en-us/library/windows/hardware/ff551803(v=vs.85).aspx */
      *lpBytesReturned = nOutBufferSize; /* an empty OutputBuffer will be returned */
      SetLastError(ERROR_CALL_NOT_IMPLEMENTED);
      return FALSE;
    }
    case IOCTL_SERIAL_SET_BAUD_RATE:
    {
      if (pServerSerialDriver->set_baud_rate)
      {
        SERIAL_BAUD_RATE* pBaudRate = (SERIAL_BAUD_RATE*)lpInBuffer;
 
        WINPR_ASSERT(nInBufferSize >= sizeof(SERIAL_BAUD_RATE));
        if (nInBufferSize < sizeof(SERIAL_BAUD_RATE))
        {
          SetLastError(ERROR_INVALID_PARAMETER);
          return FALSE;
        }
 
        return pServerSerialDriver->set_baud_rate(pComm, pBaudRate);
      }
      break;
    }
    case IOCTL_SERIAL_GET_BAUD_RATE:
    {
      if (pServerSerialDriver->get_baud_rate)
      {
        SERIAL_BAUD_RATE* pBaudRate = (SERIAL_BAUD_RATE*)lpOutBuffer;
 
        WINPR_ASSERT(nOutBufferSize >= sizeof(SERIAL_BAUD_RATE));
        if (nOutBufferSize < sizeof(SERIAL_BAUD_RATE))
        {
          SetLastError(ERROR_INSUFFICIENT_BUFFER);
          return FALSE;
        }
 
        if (!pServerSerialDriver->get_baud_rate(pComm, pBaudRate))
          return FALSE;
 
        *lpBytesReturned = sizeof(SERIAL_BAUD_RATE);
        return TRUE;
      }
      break;
    }
    case IOCTL_SERIAL_GET_PROPERTIES:
    {
      if (pServerSerialDriver->get_properties)
      {
        COMMPROP* pProperties = (COMMPROP*)lpOutBuffer;
 
        WINPR_ASSERT(nOutBufferSize >= sizeof(COMMPROP));
        if (nOutBufferSize < sizeof(COMMPROP))
        {
          SetLastError(ERROR_INSUFFICIENT_BUFFER);
          return FALSE;
        }
 
        if (!pServerSerialDriver->get_properties(pComm, pProperties))
          return FALSE;
 
        *lpBytesReturned = sizeof(COMMPROP);
        return TRUE;
      }
      break;
    }
    case IOCTL_SERIAL_SET_CHARS:
    {
      if (pServerSerialDriver->set_serial_chars)
      {
        SERIAL_CHARS* pSerialChars = (SERIAL_CHARS*)lpInBuffer;
 
        WINPR_ASSERT(nInBufferSize >= sizeof(SERIAL_CHARS));
        if (nInBufferSize < sizeof(SERIAL_CHARS))
        {
          SetLastError(ERROR_INVALID_PARAMETER);
          return FALSE;
        }
 
        return pServerSerialDriver->set_serial_chars(pComm, pSerialChars);
      }
      break;
    }
    case IOCTL_SERIAL_GET_CHARS:
    {
      if (pServerSerialDriver->get_serial_chars)
      {
        SERIAL_CHARS* pSerialChars = (SERIAL_CHARS*)lpOutBuffer;
 
        WINPR_ASSERT(nOutBufferSize >= sizeof(SERIAL_CHARS));
        if (nOutBufferSize < sizeof(SERIAL_CHARS))
        {
          SetLastError(ERROR_INSUFFICIENT_BUFFER);
          return FALSE;
        }
 
        if (!pServerSerialDriver->get_serial_chars(pComm, pSerialChars))
          return FALSE;
 
        *lpBytesReturned = sizeof(SERIAL_CHARS);
        return TRUE;
      }
      break;
    }
    case IOCTL_SERIAL_SET_LINE_CONTROL:
    {
      if (pServerSerialDriver->set_line_control)
      {
        SERIAL_LINE_CONTROL* pLineControl = (SERIAL_LINE_CONTROL*)lpInBuffer;
 
        WINPR_ASSERT(nInBufferSize >= sizeof(SERIAL_LINE_CONTROL));
        if (nInBufferSize < sizeof(SERIAL_LINE_CONTROL))
        {
          SetLastError(ERROR_INVALID_PARAMETER);
          return FALSE;
        }
 
        return pServerSerialDriver->set_line_control(pComm, pLineControl);
      }
      break;
    }
    case IOCTL_SERIAL_GET_LINE_CONTROL:
    {
      if (pServerSerialDriver->get_line_control)
      {
        SERIAL_LINE_CONTROL* pLineControl = (SERIAL_LINE_CONTROL*)lpOutBuffer;
 
        WINPR_ASSERT(nOutBufferSize >= sizeof(SERIAL_LINE_CONTROL));
        if (nOutBufferSize < sizeof(SERIAL_LINE_CONTROL))
        {
          SetLastError(ERROR_INSUFFICIENT_BUFFER);
          return FALSE;
        }
 
        if (!pServerSerialDriver->get_line_control(pComm, pLineControl))
          return FALSE;
 
        *lpBytesReturned = sizeof(SERIAL_LINE_CONTROL);
        return TRUE;
      }
      break;
    }
    case IOCTL_SERIAL_SET_HANDFLOW:
    {
      if (pServerSerialDriver->set_handflow)
      {
        SERIAL_HANDFLOW* pHandflow = (SERIAL_HANDFLOW*)lpInBuffer;
 
        WINPR_ASSERT(nInBufferSize >= sizeof(SERIAL_HANDFLOW));
        if (nInBufferSize < sizeof(SERIAL_HANDFLOW))
        {
          SetLastError(ERROR_INVALID_PARAMETER);
          return FALSE;
        }
 
        return pServerSerialDriver->set_handflow(pComm, pHandflow);
      }
      break;
    }
    case IOCTL_SERIAL_GET_HANDFLOW:
    {
      if (pServerSerialDriver->get_handflow)
      {
        SERIAL_HANDFLOW* pHandflow = (SERIAL_HANDFLOW*)lpOutBuffer;
 
        WINPR_ASSERT(nOutBufferSize >= sizeof(SERIAL_HANDFLOW));
        if (nOutBufferSize < sizeof(SERIAL_HANDFLOW))
        {
          SetLastError(ERROR_INSUFFICIENT_BUFFER);
          return FALSE;
        }
 
        if (!pServerSerialDriver->get_handflow(pComm, pHandflow))
          return FALSE;
 
        *lpBytesReturned = sizeof(SERIAL_HANDFLOW);
        return TRUE;
      }
      break;
    }
    case IOCTL_SERIAL_SET_TIMEOUTS:
    {
      if (pServerSerialDriver->set_timeouts)
      {
        SERIAL_TIMEOUTS* pHandflow = (SERIAL_TIMEOUTS*)lpInBuffer;
 
        WINPR_ASSERT(nInBufferSize >= sizeof(SERIAL_TIMEOUTS));
        if (nInBufferSize < sizeof(SERIAL_TIMEOUTS))
        {
          SetLastError(ERROR_INVALID_PARAMETER);
          return FALSE;
        }
 
        return pServerSerialDriver->set_timeouts(pComm, pHandflow);
      }
      break;
    }
    case IOCTL_SERIAL_GET_TIMEOUTS:
    {
      if (pServerSerialDriver->get_timeouts)
      {
        SERIAL_TIMEOUTS* pHandflow = (SERIAL_TIMEOUTS*)lpOutBuffer;
 
        WINPR_ASSERT(nOutBufferSize >= sizeof(SERIAL_TIMEOUTS));
        if (nOutBufferSize < sizeof(SERIAL_TIMEOUTS))
        {
          SetLastError(ERROR_INSUFFICIENT_BUFFER);
          return FALSE;
        }
 
        if (!pServerSerialDriver->get_timeouts(pComm, pHandflow))
          return FALSE;
 
        *lpBytesReturned = sizeof(SERIAL_TIMEOUTS);
        return TRUE;
      }
      break;
    }
    case IOCTL_SERIAL_SET_DTR:
    {
      if (pServerSerialDriver->set_dtr)
      {
        return pServerSerialDriver->set_dtr(pComm);
      }
      break;
    }
    case IOCTL_SERIAL_CLR_DTR:
    {
      if (pServerSerialDriver->clear_dtr)
      {
        return pServerSerialDriver->clear_dtr(pComm);
      }
      break;
    }
    case IOCTL_SERIAL_SET_RTS:
    {
      if (pServerSerialDriver->set_rts)
      {
        return pServerSerialDriver->set_rts(pComm);
      }
      break;
    }
    case IOCTL_SERIAL_CLR_RTS:
    {
      if (pServerSerialDriver->clear_rts)
      {
        return pServerSerialDriver->clear_rts(pComm);
      }
      break;
    }
    case IOCTL_SERIAL_GET_MODEMSTATUS:
    {
      if (pServerSerialDriver->get_modemstatus)
      {
        ULONG* pRegister = (ULONG*)lpOutBuffer;
 
        WINPR_ASSERT(nOutBufferSize >= sizeof(ULONG));
        if (nOutBufferSize < sizeof(ULONG))
        {
          SetLastError(ERROR_INSUFFICIENT_BUFFER);
          return FALSE;
        }
 
        if (!pServerSerialDriver->get_modemstatus(pComm, pRegister))
          return FALSE;
 
        CommLog_Print(WLOG_DEBUG, "modem status %s" PRIx32,
                      comm_ioctl_modem_status_string(*pRegister, buffer, sizeof(buffer)));
        *lpBytesReturned = sizeof(ULONG);
        return TRUE;
      }
      break;
    }
    case IOCTL_SERIAL_SET_WAIT_MASK:
    {
      if (pServerSerialDriver->set_wait_mask)
      {
        ULONG* pWaitMask = (ULONG*)lpInBuffer;
 
        WINPR_ASSERT(nInBufferSize >= sizeof(ULONG));
        if (nInBufferSize < sizeof(ULONG))
        {
          SetLastError(ERROR_INVALID_PARAMETER);
          return FALSE;
        }
 
        const BOOL rc = pServerSerialDriver->set_wait_mask(pComm, pWaitMask);
        CommLog_Print(WLOG_DEBUG, "set_wait_mask %s -> %d",
                      CommSerialEvString(*pWaitMask, buffer, sizeof(buffer)), rc);
        return rc;
      }
      break;
    }
    case IOCTL_SERIAL_GET_WAIT_MASK:
    {
      if (pServerSerialDriver->get_wait_mask)
      {
        ULONG* pWaitMask = (ULONG*)lpOutBuffer;
 
        WINPR_ASSERT(nOutBufferSize >= sizeof(ULONG));
        if (nOutBufferSize < sizeof(ULONG))
        {
          SetLastError(ERROR_INSUFFICIENT_BUFFER);
          return FALSE;
        }
 
        if (!pServerSerialDriver->get_wait_mask(pComm, pWaitMask))
          return FALSE;
 
        CommLog_Print(WLOG_DEBUG, "get_wait_mask %s",
                      CommSerialEvString(*pWaitMask, buffer, sizeof(buffer)));
        *lpBytesReturned = sizeof(ULONG);
        return TRUE;
      }
      break;
    }
    case IOCTL_SERIAL_WAIT_ON_MASK:
    {
      if (pServerSerialDriver->wait_on_mask)
      {
        ULONG* pOutputMask = (ULONG*)lpOutBuffer;
 
        WINPR_ASSERT(nOutBufferSize >= sizeof(ULONG));
        if (nOutBufferSize < sizeof(ULONG))
        {
          SetLastError(ERROR_INSUFFICIENT_BUFFER);
          return FALSE;
        }
 
        const BOOL rc = pServerSerialDriver->wait_on_mask(pComm, pOutputMask);
 
        *lpBytesReturned = sizeof(ULONG);
        CommLog_Print(WLOG_DEBUG, "wait_on_mask %s -> %d",
                      CommSerialEvString(*pOutputMask, buffer, sizeof(buffer)), rc);
        return rc;
      }
      break;
    }
    case IOCTL_SERIAL_SET_QUEUE_SIZE:
    {
      if (pServerSerialDriver->set_queue_size)
      {
        SERIAL_QUEUE_SIZE* pQueueSize = (SERIAL_QUEUE_SIZE*)lpInBuffer;
 
        WINPR_ASSERT(nInBufferSize >= sizeof(SERIAL_QUEUE_SIZE));
        if (nInBufferSize < sizeof(SERIAL_QUEUE_SIZE))
        {
          SetLastError(ERROR_INVALID_PARAMETER);
          return FALSE;
        }
 
        return pServerSerialDriver->set_queue_size(pComm, pQueueSize);
      }
      break;
    }
    case IOCTL_SERIAL_PURGE:
    {
      if (pServerSerialDriver->purge)
      {
        ULONG* pPurgeMask = (ULONG*)lpInBuffer;
 
        WINPR_ASSERT(nInBufferSize >= sizeof(ULONG));
        if (nInBufferSize < sizeof(ULONG))
        {
          SetLastError(ERROR_INVALID_PARAMETER);
          return FALSE;
        }
 
        return pServerSerialDriver->purge(pComm, pPurgeMask);
      }
      break;
    }
    case IOCTL_SERIAL_GET_COMMSTATUS:
    {
      if (pServerSerialDriver->get_commstatus)
      {
        SERIAL_STATUS* pCommstatus = (SERIAL_STATUS*)lpOutBuffer;
 
        WINPR_ASSERT(nOutBufferSize >= sizeof(SERIAL_STATUS));
        if (nOutBufferSize < sizeof(SERIAL_STATUS))
        {
          SetLastError(ERROR_INSUFFICIENT_BUFFER);
          return FALSE;
        }
 
        if (!pServerSerialDriver->get_commstatus(pComm, pCommstatus))
          return FALSE;
 
        *lpBytesReturned = sizeof(SERIAL_STATUS);
        return TRUE;
      }
      break;
    }
    case IOCTL_SERIAL_SET_BREAK_ON:
    {
      if (pServerSerialDriver->set_break_on)
      {
        return pServerSerialDriver->set_break_on(pComm);
      }
      break;
    }
    case IOCTL_SERIAL_SET_BREAK_OFF:
    {
      if (pServerSerialDriver->set_break_off)
      {
        return pServerSerialDriver->set_break_off(pComm);
      }
      break;
    }
    case IOCTL_SERIAL_SET_XOFF:
    {
      if (pServerSerialDriver->set_xoff)
      {
        return pServerSerialDriver->set_xoff(pComm);
      }
      break;
    }
    case IOCTL_SERIAL_SET_XON:
    {
      if (pServerSerialDriver->set_xon)
      {
        return pServerSerialDriver->set_xon(pComm);
      }
      break;
    }
    case IOCTL_SERIAL_GET_DTRRTS:
    {
      if (pServerSerialDriver->get_dtrrts)
      {
        ULONG* pMask = (ULONG*)lpOutBuffer;
 
        WINPR_ASSERT(nOutBufferSize >= sizeof(ULONG));
        if (nOutBufferSize < sizeof(ULONG))
        {
          SetLastError(ERROR_INSUFFICIENT_BUFFER);
          return FALSE;
        }
 
        if (!pServerSerialDriver->get_dtrrts(pComm, pMask))
          return FALSE;
 
        *lpBytesReturned = sizeof(ULONG);
        return TRUE;
      }
      break;
    }
    case IOCTL_SERIAL_CONFIG_SIZE:
    {
      if (pServerSerialDriver->config_size)
      {
        ULONG* pSize = (ULONG*)lpOutBuffer;
 
        WINPR_ASSERT(nOutBufferSize >= sizeof(ULONG));
        if (nOutBufferSize < sizeof(ULONG))
        {
          SetLastError(ERROR_INSUFFICIENT_BUFFER);
          return FALSE;
        }
 
        if (!pServerSerialDriver->config_size(pComm, pSize))
          return FALSE;
 
        *lpBytesReturned = sizeof(ULONG);
        return TRUE;
      }
      break;
    }
    case IOCTL_SERIAL_IMMEDIATE_CHAR:
    {
      if (pServerSerialDriver->immediate_char)
      {
        UCHAR* pChar = (UCHAR*)lpInBuffer;
 
        WINPR_ASSERT(nInBufferSize >= sizeof(UCHAR));
        if (nInBufferSize < sizeof(UCHAR))
        {
          SetLastError(ERROR_INVALID_PARAMETER);
          return FALSE;
        }
 
        return pServerSerialDriver->immediate_char(pComm, pChar);
      }
      break;
    }
    case IOCTL_SERIAL_RESET_DEVICE:
    {
      if (pServerSerialDriver->reset_device)
      {
        return pServerSerialDriver->reset_device(pComm);
      }
      break;
    }
    default:
      break;
  }
 
  CommLog_Print(
      WLOG_WARN, _T("unsupported IoControlCode=[0x%08" PRIX32 "] %s (remote serial driver: %s)"),
      dwIoControlCode, _comm_serial_ioctl_name(dwIoControlCode), pServerSerialDriver->name);
  SetLastError(ERROR_CALL_NOT_IMPLEMENTED); /* => STATUS_NOT_IMPLEMENTED */
  return FALSE;
}
 
BOOL CommDeviceIoControl(HANDLE hDevice, DWORD dwIoControlCode, LPVOID lpInBuffer,
                         DWORD nInBufferSize, LPVOID lpOutBuffer, DWORD nOutBufferSize,
                         LPDWORD lpBytesReturned, LPOVERLAPPED lpOverlapped)
{
  WINPR_COMM* pComm = (WINPR_COMM*)hDevice;
  BOOL result = 0;
 
  if (hDevice == INVALID_HANDLE_VALUE)
  {
    SetLastError(ERROR_INVALID_HANDLE);
    return FALSE;
  }
 
  if (!CommIsHandled(hDevice))
    return FALSE;
 
  if (!pComm->fd)
  {
    SetLastError(ERROR_INVALID_HANDLE);
    return FALSE;
  }
 
  result = s_CommDeviceIoControl(hDevice, dwIoControlCode, lpInBuffer, nInBufferSize, lpOutBuffer,
                                 nOutBufferSize, lpBytesReturned, lpOverlapped);
 
  if (lpBytesReturned && *lpBytesReturned != nOutBufferSize)
  {
    /* This might be a hint for a bug, especially when result==TRUE */
    CommLog_Print(WLOG_WARN,
                  "IoControlCode=[0x%08" PRIX32 "] %s: lpBytesReturned=%" PRIu32
                  " and nOutBufferSize=%" PRIu32 " are different!",
                  dwIoControlCode, _comm_serial_ioctl_name(dwIoControlCode), *lpBytesReturned,
                  nOutBufferSize);
  }
 
  if (pComm->permissive)
  {
    if (!result)
    {
      CommLog_Print(WLOG_WARN,
                    "[permissive]: IoControlCode=[0x%08" PRIX32 "] %s failed, ignoring",
                    dwIoControlCode, _comm_serial_ioctl_name(dwIoControlCode));
    }
 
    return TRUE; /* always! */
  }
 
  return result;
}
 
int comm_ioctl_tcsetattr(int fd, int optional_actions, const struct termios* termios_p)
{
  struct termios currentState = WINPR_C_ARRAY_INIT;
  size_t count = 0;
  do
  {
    const int src = tcsetattr(fd, optional_actions, termios_p);
    if (src < 0)
    {
      char buffer[64] = WINPR_C_ARRAY_INIT;
      CommLog_Print(WLOG_WARN, "[%" PRIuz "] tcsetattr failure, errno: %s [%d]", count,
                    winpr_strerror(errno, buffer, sizeof(buffer)), errno);
      return src;
    }
 
    /* NB: tcsetattr() can succeed even if not all changes have been applied. */
    const int rrc = tcgetattr(fd, &currentState);
    if (rrc < 0)
    {
      char buffer[64] = WINPR_C_ARRAY_INIT;
      CommLog_Print(WLOG_WARN, "[%" PRIuz "] tcgetattr failure, errno: %s [%d]", count,
                    winpr_strerror(errno, buffer, sizeof(buffer)), errno);
      return rrc;
    }
    // NOLINTNEXTLINE(bugprone-suspicious-memory-comparison,cert-exp42-c,cert-flp37-c)
  } while ((memcmp(&currentState, termios_p, sizeof(struct termios)) != 0) && (count++ < 2));
 
  return 0;
}
 
static const char* comm_ioctl_modem_flag_str(ULONG flag)
{
  switch (flag)
  {
    case SERIAL_MSR_DCTS:
      return "SERIAL_MSR_DCTS";
    case SERIAL_MSR_DDSR:
      return "SERIAL_MSR_DDSR";
    case SERIAL_MSR_TERI:
      return "SERIAL_MSR_TERI";
    case SERIAL_MSR_DDCD:
      return "SERIAL_MSR_DDCD";
    case SERIAL_MSR_CTS:
      return "SERIAL_MSR_CTS";
    case SERIAL_MSR_DSR:
      return "SERIAL_MSR_DSR";
    case SERIAL_MSR_RI:
      return "SERIAL_MSR_RI";
    case SERIAL_MSR_DCD:
      return "SERIAL_MSR_DCD";
    default:
      return "SERIAL_MSR_UNKNOWN";
  }
}
 
const char* comm_ioctl_modem_status_string(ULONG status, char* buffer, size_t size)
{
  const ULONG flags[] = { SERIAL_MSR_DCTS, SERIAL_MSR_DDSR, SERIAL_MSR_TERI, SERIAL_MSR_DDCD,
                        SERIAL_MSR_CTS,  SERIAL_MSR_DSR,  SERIAL_MSR_RI,   SERIAL_MSR_DCD
 
  };
  winpr_str_append("{", buffer, size, "");
 
  const char* sep = "";
  for (size_t x = 0; x < ARRAYSIZE(flags); x++)
  {
    const ULONG flag = flags[x];
    if (status & flag)
    {
      winpr_str_append(comm_ioctl_modem_flag_str(flag), buffer, size, sep);
      sep = "|";
    }
  }
 
  char number[32] = WINPR_C_ARRAY_INIT;
  (void)_snprintf(number, sizeof(number), "}[0x%08" PRIx32 "]", status);
  winpr_str_append(number, buffer, size, "");
  return buffer;
}