enumser.cpp

列举当前所有的串口

#include "stdafx.h"
#include "enumser.h"





///////////////////////////// Statics / Locals ////////////////////////////////

#ifdef _DEBUG
#undef THIS_FILE
#define new DEBUG_NEW
static char BASED_CODE THIS_FILE[] = __FILE__;
#endif




///////////////////////////// Implementation //////////////////////////////////

void EnumerateSerialPorts(CUIntArray& ports)
{
  //Make sure we clear out any elements which may already be in the array
  ports.RemoveAll();

  //Determine what OS we are running on
  OSVERSIONINFO osvi;
  osvi.dwOSVersionInfoSize = sizeof(OSVERSIONINFO);
  BOOL bGetVer = GetVersionEx(&osvi);

  //On NT use the QueryDosDevice API
  if (bGetVer && (osvi.dwPlatformId == VER_PLATFORM_WIN32_NT))
  {
    //Use QueryDosDevice to look for all devices of the form COMx. This is a better
    //solution as it means that no ports have to be opened at all.
    TCHAR szDevices[65535];
    DWORD dwChars = QueryDosDevice(NULL, szDevices, 65535);
    if (dwChars)
    {
      int i=0;

      for (;;)
      {
        //Get the current device name
        TCHAR* pszCurrentDevice = &szDevices[i];

        //If it looks like "COMX" then
        //add it to the array which will be returned
        int nLen = _tcslen(pszCurrentDevice);
        if (nLen > 3 && _tcsnicmp(pszCurrentDevice, _T("COM"), 3) == 0)
        {
          //Work out the port number
          int nPort = _ttoi(&pszCurrentDevice[3]);
          ports.Add(nPort);
        }

        // Go to next NULL character
        while(szDevices[i] != _T('\0'))
          i++;

        // Bump pointer to the next string
        i++;

        // The list is double-NULL terminated, so if the character is
        // now NULL, we're at the end
        if (szDevices[i] == _T('\0'))
          break;
      }
    }
    else
      TRACE(_T("Failed in call to QueryDosDevice, GetLastError:%d\n"), GetLastError());
  }
  else
  {
    //On 95/98 open up each port to determine their existence

    //Up to 255 COM ports are supported so we iterate through all of them seeing
    //if we can open them or if we fail to open them, get an access denied or general error error.
    //Both of these cases indicate that there is a COM port at that number. 
    for (UINT i=1; i<256; i++)
    {
      //Form the Raw device name
      CString sPort;
      sPort.Format(_T("\\\\.\\COM%d"), i);

      //Try to open the port
      BOOL bSuccess = FALSE;
      HANDLE hPort = ::CreateFile(sPort, GENERIC_READ | GENERIC_WRITE, 0, 0, OPEN_EXISTING, 0, 0);
      if (hPort == INVALID_HANDLE_VALUE)
      {
        DWORD dwError = GetLastError();

        //Check to see if the error was because some other app had the port open or a general failure
        if (dwError == ERROR_ACCESS_DENIED || dwError == ERROR_GEN_FAILURE)
          bSuccess = TRUE;
      }
      else
      {
        //The port was opened successfully
        bSuccess = TRUE;

        //Don't forget to close the port, since we are going to do nothing with it anyway
        CloseHandle(hPort);
      }

      //Add the port number to the array which will be returned
      if (bSuccess)
        ports.Add(i);
    }
  }
}