Methods Collection of Enumerating Com Port in Windows, by C

Posted 2020-09-22 wzzkaifa

     According to this stack overflow thread, PJ Naughter has implemented 9 methods to emunerate com port in Windows. That code was namedEnumSerialPorts.


     As my using, I found some method would list non-existed com ports. for example:

My computer com port be :

 But the output of  PJ Naughte‘s EnumSerialPorts be :

CreateFile method reports
COM1
COM4
COM5
COM98
COM99
QueryDosDevice method reports
COM5
COM1
COM98
COM99
COM4
GetDefaultCommConfig method reports
COM1
COM4
COM5
COM98
COM99
Device Manager (SetupAPI - GUID_DEVINTERFACE_COMPORT) reports
COM1 <通訊連接埠>
COM4 <USB Serial Port>
Device Manager (SetupAPI - Ports Device information set) reports
COM99 <Bluetooth Serial Port>
COM4 <USB Serial Port>
COM1 <通訊連接埠>
COM98 <Bluetooth Serial Port>
COM5 <USB-SERIAL CH340>
EnumPorts method reports
COM1
COM2
COM4
COM7
COM8
COM10
COM6
COM5
COM98
COM99
COM9
COM11
COM12
COM13
COM14
COM16
COM17
COM18
COM19
COM20
COM21
COM22
COM23
COM24
COM25
COM26
COM27
COM28
COM29
COM30
COM31
COM32
COM3
WMI method reports
COM1 <通訊連接埠 (COM1)>
ComDB method reports
COM1
COM3
COM4
COM5
COM6
COM7
COM8
COM9
COM22
COM23
COM24
COM25
COM26
COM27
COM28
COM29
COM30
COM31
COM32
COM98
COM99
Registry method reports
COM98
COM99
COM5
COM1
COM4

    Otherwise, that code are too extrvagen, those is hard to separate into an individual function: it is too much dependency on the other functions.

I has reorganized those functions being independent forms in C(instead of C++), those are more portable and useful. I also eliminated some methods which would report unused com ports.

My code be :

/*
 Enumerating com ports in Windows 

 original by PJ Naughter, 1998 - 2013 
 http://www.naughter.com/enumser.html  (Web: www.naughter.com, Email: [email protected])

 reorganize by Gaiger Chen , Jul, 2015

 NO COPYRIGHT,  welcome to use for everyone.
*/

#include <windows.h>

#include <stdio.h>
#include <tchar.h>
#include <setupapi.h>
#include <locale.h>

#define MAX_PORT_NUM      (256)
#define MAX_STR_LEN       (256*sizeof(TCHAR))


/*assure portName be double ARRAY , not double point*/
BOOL EnumerateComPortByCreateFile(UINT *pNumber, TCHAR *pPortName, int strMaxLen)
{
 UINT i, jj;
 INT ret; 
 TCHAR *pTempPortName; 
 
 *pNumber = 0;
 jj = 0;
 pTempPortName = (TCHAR*)HeapAlloc(GetProcessHeap(),
    HEAP_GENERATE_EXCEPTIONS|HEAP_ZERO_MEMORY, 
    strMaxLen*sizeof(pTempPortName));

 ret = FALSE;

 for (i = 1; i<= 255; i++){    
  HANDLE hSerial;

  _stprintf_s(pTempPortName, strMaxLen, TEXT("\\\\.\\COM%u"), i);

  hSerial = CreateFile(pTempPortName, GENERIC_READ | GENERIC_WRITE, 
   0, 0, OPEN_EXISTING, 0, 0);

  if(INVALID_HANDLE_VALUE == hSerial)
   continue;

  _tcsncpy(pPortName + jj*strMaxLen, pTempPortName, 
   _tcsnlen(pTempPortName, strMaxLen));

  jj++;
 }/*for [i MAX_PORT_NUM] */

 HeapFree(GetProcessHeap(), 0, pTempPortName); pTempPortName = NULL;
 *pNumber = jj;

 if(0 <jj)
  ret = TRUE;

 return ret;
}/*EnumerateComPortByCreateFile*/


BOOL EnumerateComPortQueryDosDevice(UINT *pNumber, TCHAR *pPortName, int strMaxLen)
{
 UINT i, jj;
 INT ret;

 OSVERSIONINFOEX osvi;
 ULONGLONG dwlConditionMask;
 DWORD dwChars;
 
 TCHAR *pDevices;   
 UINT nChars;

 ret = FALSE;
 
 memset(&osvi, 0, sizeof(osvi));
 osvi.dwOSVersionInfoSize = sizeof(OSVERSIONINFO);
 osvi.dwPlatformId = VER_PLATFORM_WIN32_NT;
 dwlConditionMask = 0;

 VER_SET_CONDITION(dwlConditionMask, VER_PLATFORMID, VER_EQUAL);

 if(FALSE == VerifyVersionInfo(&osvi, VER_PLATFORMID, dwlConditionMask))
 {
   DWORD dwError = GetLastError();
  _tprintf(TEXT("VerifyVersionInfo error, %d\n", dwError));
  return -1;
 }/*if*/

   
 pDevices = NULL;

 nChars = 4096;   
 pDevices = (TCHAR*)HeapAlloc(GetProcessHeap(), 
  HEAP_GENERATE_EXCEPTIONS, nChars*sizeof(TCHAR));

 while(0 < nChars)
 {
  dwChars = QueryDosDevice(NULL, pDevices, nChars);

  if(0 == dwChars)
  {
   DWORD dwError = GetLastError();

   if(ERROR_INSUFFICIENT_BUFFER == dwError)
   {      
    nChars *= 2;    
    HeapFree(GetProcessHeap(), 0, pDevices);    
    pDevices = (TCHAR*)HeapAlloc(GetProcessHeap(), 
     HEAP_GENERATE_EXCEPTIONS, nChars*sizeof(TCHAR));

    continue;
   }/*if ERROR_INSUFFICIENT_BUFFER == dwError*/
   
   _tprintf(TEXT("QueryDosDevice error, %d\n", dwError));
   return -1;     
  }/*if */


  //printf("dwChars = %d\n", dwChars);
  i = 0;
  jj = 0;
  while (TEXT(‘\0‘) != pDevices[i] )
  {
   TCHAR* pszCurrentDevice;
   size_t nLen;
   pszCurrentDevice = &(pDevices[i]);
   nLen = _tcslen(pszCurrentDevice);

   //_tprintf(TEXT("%s\n"), &pTargetPathStr[i]);
   if (3 < nLen)
            {
              if ((0 == _tcsnicmp(pszCurrentDevice, TEXT("COM"), 3))
      && FALSE != isdigit(pszCurrentDevice[3]) )
              {
                //Work out the port number                
    _tcsncpy(pPortName + jj*strMaxLen, 
     pszCurrentDevice, MAX_STR_LEN);
    jj++; 
    
              }
            }

   i += (nLen + 1);
  }
  
  break;
 }/*while*/
 
 if(NULL != pDevices)
  HeapFree(GetProcessHeap(), 0, pDevices); 
 
  
 *pNumber = jj;

 if(0 < jj)
  ret = TRUE;

 return ret;
}/*EnumerateComPortByQueryDosDevice*/


BOOL EnumerateComPortByGetDefaultCommConfig(UINT *pNumber, TCHAR *pPortName, 
  int strMaxLen)
{
 UINT i, jj;
 INT ret;
 
 TCHAR *pTempPortName; 

 pTempPortName = (TCHAR*)HeapAlloc(GetProcessHeap(), 
  HEAP_GENERATE_EXCEPTIONS| HEAP_ZERO_MEMORY, strMaxLen);

 *pNumber = 0;
 jj = 0;
 ret = FALSE;

 for (i = 1; i<=255; i++){    

  //Form the Raw device name    
  COMMCONFIG cc;
  DWORD dwSize ;

  dwSize = sizeof(COMMCONFIG);

  _stprintf_s(pTempPortName, strMaxLen/2, TEXT("COM%u"), i);

  if (FALSE == GetDefaultCommConfig(pTempPortName, &cc, &dwSize))
    continue;
    
  _tcsncpy(pPortName + jj*strMaxLen, pTempPortName, 
   _tcsnlen(pTempPortName, strMaxLen));
  jj++;
 }/*for [1 255] */

 HeapFree(GetProcessHeap(), 0, pTempPortName);
  pTempPortName = NULL;
 
 *pNumber = jj;

 if(0 <jj)
  ret = TRUE;

 return ret;
}/*EnumerateComPortByGetDefaultCommConfig*/


BOOL EnumerateComPortSetupAPI_GUID_DEVINTERFACE_COMPORT(UINT *pNumber, 
   TCHAR *pPortName, int strMaxLen, TCHAR *pFriendName)
{ 
 UINT i, jj;
 INT ret;
 
 TCHAR *pTempPortName;
 HMODULE hLibrary;
 TCHAR szFullPath[_MAX_PATH];

 GUID guid;
 HDEVINFO hDevInfoSet;
  

 typedef HKEY (__stdcall SetupDiOpenDevRegKeyFunType)
  (HDEVINFO, PSP_DEVINFO_DATA, DWORD, DWORD, DWORD, REGSAM);
 
 //typedef BOOL (__stdcall SetupDiClassGuidsFromNameFunType)
 // (LPCTSTR, LPGUID, DWORD, PDWORD);

 typedef BOOL (__stdcall SetupDiDestroyDeviceInfoListFunType)
  (HDEVINFO);
 typedef BOOL (__stdcall SetupDiEnumDeviceInfoFunType)
  (HDEVINFO, DWORD, PSP_DEVINFO_DATA);

 typedef HDEVINFO (__stdcall SetupDiGetClassDevsFunType)
  (LPGUID, LPCTSTR, HWND, DWORD);

 typedef BOOL (__stdcall SetupDiGetDeviceRegistryPropertyFunType)
  (HDEVINFO, PSP_DEVINFO_DATA, DWORD, PDWORD, PBYTE, DWORD, PDWORD);

 SetupDiOpenDevRegKeyFunType* SetupDiOpenDevRegKeyFunPtr;

 SetupDiGetClassDevsFunType *SetupDiGetClassDevsFunPtr;
 SetupDiGetDeviceRegistryPropertyFunType *SetupDiGetDeviceRegistryPropertyFunPtr;

 SetupDiDestroyDeviceInfoListFunType *SetupDiDestroyDeviceInfoListFunPtr;  
 SetupDiEnumDeviceInfoFunType *SetupDiEnumDeviceInfoFunPtr; 

 BOOL bMoreItems;
 SP_DEVINFO_DATA devInfo;

 ret = FALSE;
 jj = 0;
 szFullPath[0] = _T(‘\0‘); 

 //Get the Windows System32 directory
 
 
 if(0 == GetSystemDirectory(szFullPath, _countof(szFullPath)))
 {
  _tprintf(TEXT("CEnumerateSerial::UsingSetupAPI1 failed, Error:%u\n"), 
   GetLastError());
  return FALSE;
 }/*if*/
 

 //Setup the full path and delegate to LoadLibrary    
#pragma warning(suppress: 6102) //There is a bug with the SAL annotation of GetSystemDirectory in the Windows 8.1 SDK
 _tcscat_s(szFullPath, _countof(szFullPath), _T("\\"));
 _tcscat_s(szFullPath, _countof(szFullPath), TEXT("SETUPAPI.DLL"));
 hLibrary = LoadLibrary(szFullPath);

 
 SetupDiOpenDevRegKeyFunPtr = 
  (SetupDiOpenDevRegKeyFunType*)GetProcAddress(hLibrary, "SetupDiOpenDevRegKey");
  
#if defined _UNICODE 
 SetupDiGetClassDevsFunPtr = 
  (SetupDiGetClassDevsFunType*)GetProcAddress(hLibrary, "SetupDiGetClassDevsW");
 SetupDiGetDeviceRegistryPropertyFunPtr = (SetupDiGetDeviceRegistryPropertyFunType*)
  GetProcAddress(hLibrary, "SetupDiGetDeviceRegistryPropertyW");
#else
 SetupDiGetClassDevsFunPtr = 
  (SetupDiGetClassDevsFunType*)GetProcAddress(hLibrary, "SetupDiGetClassDevsA");

 SetupDiGetDeviceRegistryPropertyFunPtr = (SetupDiGetDeviceRegistryPropertyFunType*)
  GetProcAddress(hLibrary, "SetupDiGetDeviceRegistryPropertyA");
#endif

  SetupDiDestroyDeviceInfoListFunPtr = (SetupDiDestroyDeviceInfoListFunType*)
  GetProcAddress(hLibrary, "SetupDiDestroyDeviceInfoList");

 SetupDiEnumDeviceInfoFunPtr = (SetupDiEnumDeviceInfoFunType*)
  GetProcAddress(hLibrary, "SetupDiEnumDeviceInfo");

 guid = GUID_DEVINTERFACE_COMPORT;

 hDevInfoSet = SetupDiGetClassDevsFunPtr(&guid, NULL, NULL, 
  DIGCF_PRESENT | DIGCF_DEVICEINTERFACE);


 if (INVALID_HANDLE_VALUE == hDevInfoSet)
 {
  //Set the error to report
  _tprintf(TEXT("error lpfnSETUPDIGETCLASSDEVS, %d"), GetLastError());
  return FALSE;
 }/*if */
 

 //bMoreItems = TRUE;
 devInfo.cbSize = sizeof(SP_DEVINFO_DATA);
 i = 0;
 jj = 0;

 do
 {
  HKEY hDeviceKey;  
  BOOL isFound;

  isFound = FALSE;
  bMoreItems = SetupDiEnumDeviceInfoFunPtr(hDevInfoSet, i, &devInfo); 

  if(FALSE == bMoreItems)
   break;   

  i++;

  hDeviceKey = SetupDiOpenDevRegKeyFunPtr(hDevInfoSet, &devInfo, 
   DICS_FLAG_GLOBAL, 0, DIREG_DEV, KEY_QUERY_VALUE);
 
  if (INVALID_HANDLE_VALUE != hDeviceKey)
  {
   int nPort;    
   size_t nLen;
   LPTSTR pszPortName;

   nPort = 0;
   pszPortName = NULL;

   {    
    //First query for the size of the registry value 
    DWORD dwType;
    DWORD dwDataSize;
    LONG err;
    DWORD dwAllocatedSize;
    DWORD dwReturnedSize;
    dwType = 0; dwDataSize = 0; 

    err = RegQueryValueEx(hDeviceKey, TEXT("PortName"), NULL, 
     &dwType, NULL, &dwDataSize);

    if (ERROR_SUCCESS != err)    
     continue;    
    
    //Ensure the value is a string
    if (dwType != REG_SZ)    
     continue;
    
    //Allocate enough bytes for the return value
    dwAllocatedSize = dwDataSize + sizeof(TCHAR);

    /* +sizeof(TCHAR) is to allow us to NULL terminate 
     the data if it is not null terminated in the registry
    */

    pszPortName = (LPTSTR)LocalAlloc(LMEM_FIXED, dwAllocatedSize); 

    if (pszPortName == NULL)
     continue;

    //Recall RegQueryValueEx to return the data
    pszPortName[0] = _T(‘\0‘);
    dwReturnedSize = dwAllocatedSize;

    err = RegQueryValueEx(hDeviceKey, TEXT("PortName"), NULL, 
     &dwType, (LPBYTE)pszPortName, &dwReturnedSize);

    if (ERROR_SUCCESS != err)
    {
     LocalFree(pszPortName);
     pszPortName = NULL;     
     continue;
    }

    //Handle the case where the data just returned is the same size as the allocated size. This could occur where the data
    //has been updated in the registry with a non null terminator between the two calls to ReqQueryValueEx above. Rather than
    //return a potentially non-null terminated block of data, just fail the method call
    if (dwReturnedSize >= dwAllocatedSize)
     continue;        

    //NULL terminate the data if it was not returned NULL terminated because it is not stored null terminated in the registry
    if (pszPortName[dwReturnedSize/sizeof(TCHAR) - 1] != _T(‘\0‘))
     pszPortName[dwReturnedSize/sizeof(TCHAR)] = _T(‘\0‘);
   }/*local varable*/

   //If it looks like "COMX" then
   //add it to the array which will be returned
   nLen = _tcslen(pszPortName);

   if (3 < nLen)
   {
     if (0 == _tcsnicmp(pszPortName, TEXT("COM"), 3))
     {
     if(FALSE == isdigit(pszPortName[3]) )
      continue;

    //Work out the port number
     _tcsncpy(pPortName + jj*strMaxLen, pszPortName, 
     _tcsnlen(pszPortName, strMaxLen));

    //_stprintf_s(&portName[jj][0], strMaxLen, TEXT("%s"), pszPortName);          
     } else
     {
      continue;
     }/*if 0 == _tcsnicmp(pszPortName, TEXT("COM"), 3)*/
   }/*if 3 < nLen*/

   LocalFree(pszPortName);    
   isFound = TRUE;   

   //Close the key now that we are finished with it
   RegCloseKey(hDeviceKey);
  }/*INVALID_HANDLE_VALUE != hDeviceKey*/

  if(FALSE == isFound)
   continue;

  //If the port was a serial port, then also try to get its friendly name  
  {
   TCHAR szFriendlyName[1024];     
   DWORD dwSize;
   DWORD dwType;
   szFriendlyName[0] = _T(‘\0‘);
   dwSize = sizeof(szFriendlyName);
   dwType = 0;

   if( (TRUE == SetupDiGetDeviceRegistryPropertyFunPtr(hDevInfoSet, &devInfo, 
       SPDRP_DEVICEDESC, &dwType, (PBYTE)(szFriendlyName), 
       dwSize, &dwSize) ) && (REG_SZ == dwType)        
   )
   {
    _tcsncpy(pFriendName + jj*strMaxLen, &szFriendlyName[0], 
     _tcsnlen(&szFriendlyName[0], strMaxLen));
   }
   else
   {
    _stprintf_s(pFriendName + jj*strMaxLen, strMaxLen, TEXT("")); 
   }/*if SetupDiGetDeviceRegistryPropertyFunPtr */    
  }/*local variable */

  jj++;
 }while(1);

 *pNumber = jj;
 if(0 <jj)
  ret = TRUE;

 return ret;
}/*EnumerateComPortSetupAPI_GUID_DEVINTERFACE_COMPORT*/


BOOL EnumerateComPortSetupAPISetupDiClassGuidsFromNamePort(UINT *pNumber, 
  TCHAR *pPortName, int strMaxLen, TCHAR *pFriendName)
{ 
 UINT i, jj;
 INT ret;
 
 TCHAR *pTempPortName;
 HMODULE hLibrary;
 TCHAR szFullPath[_MAX_PATH];

 GUID *pGuid;
 DWORD dwGuids;
 HDEVINFO hDevInfoSet;
  

 typedef HKEY (__stdcall SetupDiOpenDevRegKeyFunType)
  (HDEVINFO, PSP_DEVINFO_DATA, DWORD, DWORD, DWORD, REGSAM);
 
 typedef BOOL (__stdcall SetupDiClassGuidsFromNameFunType)
  (LPCTSTR, LPGUID, DWORD, PDWORD);

 typedef BOOL (__stdcall SetupDiDestroyDeviceInfoListFunType)
  (HDEVINFO);
 typedef BOOL (__stdcall SetupDiEnumDeviceInfoFunType)
  (HDEVINFO, DWORD, PSP_DEVINFO_DATA);

 typedef HDEVINFO (__stdcall SetupDiGetClassDevsFunType)
  (LPGUID, LPCTSTR, HWND, DWORD);

 typedef BOOL (__stdcall SetupDiGetDeviceRegistryPropertyFunType)
  (HDEVINFO, PSP_DEVINFO_DATA, DWORD, PDWORD, PBYTE, DWORD, PDWORD);

 SetupDiOpenDevRegKeyFunType* SetupDiOpenDevRegKeyFunPtr;

 SetupDiClassGuidsFromNameFunType *SetupDiClassGuidsFromNameFunPtr;
 SetupDiGetClassDevsFunType *SetupDiGetClassDevsFunPtr;
 SetupDiGetDeviceRegistryPropertyFunType *SetupDiGetDeviceRegistryPropertyFunPtr; 

 SetupDiDestroyDeviceInfoListFunType *SetupDiDestroyDeviceInfoListFunPtr;  
 SetupDiEnumDeviceInfoFunType *SetupDiEnumDeviceInfoFunPtr; 

 BOOL bMoreItems;
 SP_DEVINFO_DATA devInfo;

 ret = FALSE;
 jj = 0;
 szFullPath[0] = _T(‘\0‘); 

 //Get the Windows System32 directory
 
 
 if(0 == GetSystemDirectory(szFullPath, _countof(szFullPath)))
 {
  _tprintf(TEXT("CEnumerateSerial::UsingSetupAPI1 failed, Error:%u\n"), 
   GetLastError());
  return FALSE;
 }/*if*/
 

 //Setup the full path and delegate to LoadLibrary    
#pragma warning(suppress: 6102) //There is a bug with the SAL annotation of GetSystemDirectory in the Windows 8.1 SDK
 _tcscat_s(szFullPath, _countof(szFullPath), _T("\\"));
 _tcscat_s(szFullPath, _countof(szFullPath), TEXT("SETUPAPI.DLL"));
 hLibrary = LoadLibrary(szFullPath);

 
 SetupDiOpenDevRegKeyFunPtr = 
  (SetupDiOpenDevRegKeyFunType*)GetProcAddress(hLibrary, "SetupDiOpenDevRegKey");
  
#if defined _UNICODE 
 SetupDiClassGuidsFromNameFunPtr = (SetupDiClassGuidsFromNameFunType*)
  GetProcAddress(hLibrary, "SetupDiGetDeviceRegistryPropertyW");
 SetupDiGetClassDevsFunPtr = 
  (SetupDiGetClassDevsFunType*)GetProcAddress(hLibrary, "SetupDiGetClassDevsW");
 SetupDiGetDeviceRegistryPropertyFunPtr
  = (SetupDiGetDeviceRegistryPropertyFunType*)GetProcAddress(hLibrary, "SetupDiGetDeviceRegistryPropertyW");
#else
 SetupDiClassGuidsFromNameFunPtr = (SetupDiClassGuidsFromNameFunType*)
  GetProcAddress(hLibrary, "SetupDiClassGuidsFromNameA");
 SetupDiGetClassDevsFunPtr = (SetupDiGetClassDevsFunType*)
  GetProcAddress(hLibrary, "SetupDiGetClassDevsA");
 SetupDiGetDeviceRegistryPropertyFunPtr = (SetupDiGetDeviceRegistryPropertyFunType*)
  GetProcAddress(hLibrary, "SetupDiGetDeviceRegistryPropertyA");
#endif

  SetupDiDestroyDeviceInfoListFunPtr = (SetupDiDestroyDeviceInfoListFunType*)
  GetProcAddress(hLibrary, "SetupDiDestroyDeviceInfoList");

 SetupDiEnumDeviceInfoFunPtr = (SetupDiEnumDeviceInfoFunType*)
  GetProcAddress(hLibrary, "SetupDiEnumDeviceInfo");

 
 //First need to convert the name "Ports" to a GUID using SetupDiClassGuidsFromName
 dwGuids = 0;
 SetupDiClassGuidsFromNameFunPtr(TEXT("Ports"), NULL, 0, &dwGuids);

 if(0 == dwGuids)  
  return FALSE;
 
 //Allocate the needed memory
 pGuid = (GUID*)HeapAlloc(GetProcessHeap(), 
  HEAP_GENERATE_EXCEPTIONS, dwGuids * sizeof(GUID));
 
 if(NULL == pGuid) 
  return FALSE;
 

 //Call the function again
 
 if (FALSE == SetupDiClassGuidsFromNameFunPtr(TEXT("Ports"), 
   pGuid, dwGuids, &dwGuids))  
 {
  return FALSE;
 }/*if*/


 hDevInfoSet = SetupDiGetClassDevsFunPtr(pGuid, NULL, NULL, 
  DIGCF_PRESENT /*| DIGCF_DEVICEINTERFACE*/);


 if (INVALID_HANDLE_VALUE == hDevInfoSet)
 {
  //Set the error to report
  _tprintf(TEXT("error SetupDiGetClassDevsFunPtr, %d"), GetLastError());
  return FALSE;
 }/*if */
 

 //bMoreItems = TRUE;
 devInfo.cbSize = sizeof(SP_DEVINFO_DATA);
 i = 0;
 jj = 0;

 do
 {
  HKEY hDeviceKey;  
  BOOL isFound;

  isFound = FALSE;
  bMoreItems = SetupDiEnumDeviceInfoFunPtr(hDevInfoSet, i, &devInfo);  
  if(FALSE == bMoreItems)
   break;   

  i++;

  hDeviceKey = SetupDiOpenDevRegKeyFunPtr(hDevInfoSet, &devInfo, 
   DICS_FLAG_GLOBAL, 0, DIREG_DEV, KEY_QUERY_VALUE);
 
  if (INVALID_HANDLE_VALUE != hDeviceKey)
  {
   int nPort;    
   size_t nLen;
   LPTSTR pszPortName;

   nPort = 0;
   pszPortName = NULL;

   {    
    //First query for the size of the registry value 
    DWORD dwType;
    DWORD dwDataSize;
    LONG err;
    DWORD dwAllocatedSize;
    DWORD dwReturnedSize;
    dwType = 0; dwDataSize = 0; 

    err = RegQueryValueEx(hDeviceKey, TEXT("PortName"), NULL, 
     &dwType, NULL, &dwDataSize);

    if (ERROR_SUCCESS != err)    
     continue;    
    
    //Ensure the value is a string
    if (dwType != REG_SZ)    
     continue;
    
    //Allocate enough bytes for the return value
    dwAllocatedSize = dwDataSize + sizeof(TCHAR);

    /* +sizeof(TCHAR) is to allow us to NULL terminate 
     the data if it is not null terminated in the registry
    */

    pszPortName = (LPTSTR)LocalAlloc(LMEM_FIXED, dwAllocatedSize); 

    if (pszPortName == NULL)
     continue;

    //Recall RegQueryValueEx to return the data
    pszPortName[0] = TEXT(‘\0‘);
    dwReturnedSize = dwAllocatedSize;

    err = RegQueryValueEx(hDeviceKey, TEXT("PortName"), NULL, 
     &dwType, (LPBYTE)pszPortName, &dwReturnedSize);

    if (ERROR_SUCCESS != err)
    {
     LocalFree(pszPortName);
     pszPortName = NULL;     
     continue;
    }

    //Handle the case where the data just returned is the same size as the allocated size. This could occur where the data
    //has been updated in the registry with a non null terminator between the two calls to ReqQueryValueEx above. Rather than
    //return a potentially non-null terminated block of data, just fail the method call
    if (dwReturnedSize >= dwAllocatedSize)
     continue;        

    //NULL terminate the data if it was not returned NULL terminated because it is not stored null terminated in the registry
    if (pszPortName[dwReturnedSize/sizeof(TCHAR) - 1] != _T(‘\0‘))
     pszPortName[dwReturnedSize/sizeof(TCHAR)] = _T(‘\0‘);
   }/*local varable*/

   //If it looks like "COMX" then
   //add it to the array which will be returned
   nLen = _tcslen(pszPortName);

   if (3 < nLen)
   {
     if (0 == _tcsnicmp(pszPortName, TEXT("COM"), 3))
     {
     if(FALSE == isdigit(pszPortName[3]) )
      continue;

    //Work out the port number
     _tcsncpy(pPortName + jj*strMaxLen, pszPortName, 
     _tcsnlen(pszPortName, strMaxLen));

    //_stprintf_s(&portName[jj][0], strMaxLen, TEXT("%s"), pszPortName);          
     }
     else
     {
      continue;
     }/*if 0 == _tcsnicmp(pszPortName, TEXT("COM"), 3)*/

   }/*if 3 < nLen*/

   LocalFree(pszPortName);    
   isFound = TRUE;  

   //Close the key now that we are finished with it
   RegCloseKey(hDeviceKey);
  }/*INVALID_HANDLE_VALUE != hDeviceKey*/

  if(FALSE == isFound)
   continue;

  //If the port was a serial port, then also try to get its friendly name  
  {
   TCHAR szFriendlyName[1024];     
   DWORD dwSize;
   DWORD dwType;
   szFriendlyName[0] = _T(‘\0‘);
   dwSize = sizeof(szFriendlyName);
   dwType = 0;

   if( (TRUE == SetupDiGetDeviceRegistryPropertyFunPtr(hDevInfoSet, &devInfo, 
       SPDRP_DEVICEDESC, &dwType, (PBYTE)(szFriendlyName), 
       dwSize, &dwSize) ) && (REG_SZ == dwType)        
   )
   {
    _tcsncpy(pFriendName + jj*strMaxLen, &szFriendlyName[0], 
     _tcsnlen(&szFriendlyName[0], strMaxLen));
   }
   else
   {
    _stprintf_s(pFriendName + jj*strMaxLen, strMaxLen, TEXT("")); 
   }/*if SetupDiGetDeviceRegistryPropertyFunPtr */    
  }/*local variable */

  jj++;
 }while(1);

 HeapFree(GetProcessHeap(), 0, pGuid);

 *pNumber = jj;

 if(0 <jj)
  ret = TRUE;

 return ret;
}/*EnumerateComPortSetupAPISetupDiClassGuidsFromNamePort*/


BOOL EnumerateComPortRegistry(UINT *pNumber, TCHAR *pPortName, int strMaxLen)
{
  //What will be the return value from this function (assume the worst) 
 UINT jj;
 BOOL ret;

 HKEY hSERIALCOMM;
 ret = FALSE;

 if ( ERROR_SUCCESS == RegOpenKeyEx(HKEY_LOCAL_MACHINE, 
  TEXT("HARDWARE\\DEVICEMAP\\SERIALCOMM"), 0, KEY_QUERY_VALUE, &hSERIALCOMM) 
  )
 {
    //Get the max value name and max value lengths
  DWORD dwMaxValueNameLen;
  DWORD dwMaxValueLen;
  DWORD dwQueryInfo;

  dwQueryInfo = RegQueryInfoKey(hSERIALCOMM, NULL, NULL,
  NULL, NULL, NULL, NULL, NULL, 
  &dwMaxValueNameLen, &dwMaxValueLen, NULL, NULL);

  if(ERROR_SUCCESS == dwQueryInfo)
  {
   DWORD dwMaxValueNameSizeInChars, dwMaxValueNameSizeInBytes,
    dwMaxValueDataSizeInChars, dwMaxValueDataSizeInBytes;

   DWORD *pValueName;
   DWORD *pValueData;

   dwMaxValueNameSizeInChars = dwMaxValueNameLen + 1; //Include space for the NULL terminator
   dwMaxValueNameSizeInBytes = dwMaxValueNameSizeInChars * sizeof(TCHAR);
   dwMaxValueDataSizeInChars = dwMaxValueLen/sizeof(TCHAR) + 1; //Include space for the NULL terminator
   dwMaxValueDataSizeInBytes = dwMaxValueDataSizeInChars * sizeof(TCHAR);
    
   //Allocate some space for the value name and value data      

   pValueName = (GUID*)HeapAlloc(GetProcessHeap(), 
    HEAP_GENERATE_EXCEPTIONS| HEAP_ZERO_MEMORY, dwMaxValueNameSizeInBytes);
   pValueData = (GUID*)HeapAlloc(GetProcessHeap(), 
    HEAP_GENERATE_EXCEPTIONS| HEAP_ZERO_MEMORY, dwMaxValueDataSizeInBytes);

   if(NULL != pValueName && NULL != pValueData)
   {    
    //Enumerate all the values underneath HKEY_LOCAL_MACHINE\HARDWARE\DEVICEMAP\SERIALCOMM
    DWORD i;
    DWORD dwType;
    DWORD dwValueNameSize;
    DWORD dwDataSize;
    LONG nEnum;

    
    dwValueNameSize = dwMaxValueNameSizeInChars;
    dwDataSize = dwMaxValueDataSizeInBytes;

    i = 0; 

    nEnum = RegEnumValue(hSERIALCOMM, i, 
     pValueName, &dwValueNameSize, NULL, &dwType,
     pValueData, &dwDataSize);

    jj = 0;
    while (ERROR_SUCCESS == nEnum)
    {
      //If the value is of the correct type, then add it to the array
     if (REG_SZ == dwType)
     {     
      _stprintf_s(pPortName + jj*strMaxLen, 
       strMaxLen, TEXT("%s"), pValueData);
      jj++;      
     }/*if */

     //Prepare for the next time around
     dwValueNameSize = dwMaxValueNameSizeInChars;
     dwDataSize = dwMaxValueDataSizeInBytes;
     ZeroMemory(pValueName, dwMaxValueNameSizeInBytes);
     ZeroMemory(pValueData, dwMaxValueDataSizeInBytes);
     i++;
     nEnum = RegEnumValue(hSERIALCOMM, i, pValueName, 
       &dwValueNameSize, NULL, &dwType, pValueData, &dwDataSize);
    }/*while*/
   }
   else
   {
    return FALSE;
   }/*if NULL != pValueName && NULL != pValueData*/

   HeapFree(GetProcessHeap(), 0, pValueName);
   HeapFree(GetProcessHeap(), 0, pValueData);
  }/*ERROR_SUCCESS == dwQueryInfo*/
    
  //Close the registry key now that we are finished with it    
  RegCloseKey(hSERIALCOMM);
     
  if (dwQueryInfo != ERROR_SUCCESS)
    return FALSE;
 }/*ERROR_SUCCESS == RegOpenKeyEx*/
  
 *pNumber = jj;

 if(0 <jj)
  ret = TRUE;

 return ret;
}/*EnumerateComPortRegistry*/



#define TIMER_BEGIN(TIMER_LABEL) \
   { unsigned int tBegin##TIMER_LABEL, tEnd##TIMER_LABEL; \
   tBegin##TIMER_LABEL = GetTime();
          
#define TIMER_END(TIMER_LABEL)  \
   tEnd##TIMER_LABEL = GetTime();\
   fprintf(stderr, "%s cost time = %d ms\n", \
   #TIMER_LABEL, tEnd##TIMER_LABEL - tBegin##TIMER_LABEL); \
   }

unsigned int GetTime(void)
{
 /*winmm.lib*/
 return ( unsigned int)timeGetTime();
}/*GetTime*/

int main(int argc, TCHAR argv[])
{ 
 TCHAR portName[MAX_PORT_NUM][MAX_STR_LEN];
 TCHAR friendlyName[MAX_PORT_NUM][MAX_STR_LEN];
 UINT i;
 UINT n;

 char* nativeLocale;

 nativeLocale = _strdup( setlocale(LC_CTYPE,NULL) );

 

 for(i = 0; i< MAX_PORT_NUM; i++)
  ZeroMemory(&portName[i][0], MAX_STR_LEN);

 _tprintf(TEXT("\nCreateFile method : \n"));
TIMER_BEGIN(EnumerateComPortByCreateFile);
 EnumerateComPortByCreateFile(&n, &portName[0][0], MAX_STR_LEN);
TIMER_END(EnumerateComPortByCreateFile);
 _tprintf(TEXT("sought %d:\n"), n);
 for(i = 0; i< n; i++) 
  _tprintf(TEXT("\t%s\n"), &portName[i][0]);
 



 for(i = 0; i< MAX_PORT_NUM; i++)
  ZeroMemory(&portName[0][0], MAX_STR_LEN);

 _tprintf(TEXT("\nQueryDosDevice method : ")); 
TIMER_BEGIN(EnumerateComPortQueryDosDevice); 
 EnumerateComPortQueryDosDevice(&n, &portName[0][0], MAX_STR_LEN);
TIMER_END(EnumerateComPortQueryDosDevice);
 _tprintf(TEXT("sought %d:\n"), n);

 for(i = 0; i< n; i++)
  _tprintf("\t%s\n", &portName[i][0]);
 


 

 for(i = 0; i< MAX_PORT_NUM; i++)
  ZeroMemory(&portName[i][0], MAX_STR_LEN);

 _tprintf(TEXT("\nGetDefaultCommConfig method : \n"));
TIMER_BEGIN(EnumerateComPortByGetDefaultCommConfig);
 EnumerateComPortByGetDefaultCommConfig(&n, &portName[0][0], MAX_STR_LEN);
TIMER_END(EnumerateComPortByGetDefaultCommConfig);
 _tprintf(TEXT("sought %d:\n"), n);

 for(i = 0; i< n; i++) 
  _tprintf(TEXT("\t%s\n"), &portName[i][0]);
 



 for(i = 0; i< MAX_PORT_NUM; i++){
  ZeroMemory(&portName[i][0], MAX_STR_LEN);
  ZeroMemory(&friendlyName[i][0], MAX_STR_LEN);
 }/*for i[i MAX_PORT_NUM]*/

 _tprintf(TEXT("\nSetupAPI GUID_DEVINTERFACE_COMPORT method : \n")); 

TIMER_BEGIN(EnumerateComPortSetupAPI_GUID_DEVINTERFACE_COMPORT);
 EnumerateComPortSetupAPI_GUID_DEVINTERFACE_COMPORT(&n, &portName[0][0], 
  MAX_STR_LEN, &friendlyName[0][0]);
TIMER_END(EnumerateComPortSetupAPI_GUID_DEVINTERFACE_COMPORT);

 _tprintf(TEXT("sought %d:\n"), n);
 
 setlocale(LC_CTYPE, "" );   
 for(i = 0; i< n; i++) 
  _tprintf(TEXT("\t%s <%s> \n"), &portName[i][0],  &friendlyName[i][0]);
 setlocale(LC_CTYPE, nativeLocale);
 



 for(i = 0; i< MAX_PORT_NUM; i++){
  ZeroMemory(&portName[i][0], MAX_STR_LEN);
  ZeroMemory(&friendlyName[i][0], MAX_STR_LEN);
 }/*for i[i MAX_PORT_NUM]*/

 _tprintf(TEXT("\nSetupAPI SetupDiClassGuidsFromNamePort method : \n"));
 
TIMER_BEGIN(EnumerateComPortSetupAPISetupDiClassGuidsFromNamePort);
 EnumerateComPortSetupAPISetupDiClassGuidsFromNamePort(&n, &portName[0][0], 
  MAX_STR_LEN, &friendlyName[0][0]);
TIMER_END(EnumerateComPortSetupAPISetupDiClassGuidsFromNamePort);

 _tprintf(TEXT("sought %d:\n"), n);
 
 setlocale(LC_CTYPE, "" );   
 for(i = 0; i< n; i++) 
  _tprintf(TEXT("\t%s <%s> \n"), &portName[i][0],  &friendlyName[i][0]);
 setlocale(LC_CTYPE, nativeLocale);


 

 for(i = 0; i< MAX_PORT_NUM; i++)
  ZeroMemory(&portName[i][0], MAX_STR_LEN);

 _tprintf(TEXT("\nRegistry method : \n"));

TIMER_BEGIN(EnumerateComPortRegistry);
 EnumerateComPortRegistry(&n, &portName[0][0], MAX_STR_LEN);
TIMER_END(EnumerateComPortRegistry);
 _tprintf(TEXT("sought %d:\n"), n);
 for(i = 0; i< n; i++) 
  _tprintf(TEXT("\t%s\n"), &portName[i][0]);


 return 0; 
}/*main*/

The output be :

CreateFile method :
EnumerateComPortByCreateFile cost time = 35 ms
sought 5:
        \\.\COM1
        \\.\COM4
        \\.\COM5
        \\.\COM98
        \\.\COM99

QueryDosDevice method : EnumerateComPortQueryDosDevice cost time = 7 ms
sought 5:
        COM5
        COM1
        COM98
        COM99
        COM4

GetDefaultCommConfig method :
EnumerateComPortByGetDefaultCommConfig cost time = 772 ms
sought 5:
        COM1
        COM4
        COM5
        COM98
        COM99

SetupAPI GUID_DEVINTERFACE_COMPORT method :
EnumerateComPortSetupAPI_GUID_DEVINTERFACE_COMPORT cost time = 12 ms
sought 2:
        COM1 <通訊連接埠>
        COM4 <USB Serial Port>

SetupAPI SetupDiClassGuidsFromNamePort method :
EnumerateComPortSetupAPISetupDiClassGuidsFromNamePort cost time = 10 ms
sought 5:
        COM99 <Bluetooth Serial Port>
        COM4 <USB Serial Port>
        COM1 <通訊連接埠>
        COM98 <Bluetooth Serial Port>
        COM5 <USB-SERIAL CH340>

Registry method :
EnumerateComPortRegistry cost time = 0 ms
sought 5:
        COM98
        COM99
        COM5
        COM1
        COM4

      Note that: EnumerateComPortSetupAPI_GUID_DEVINTERFACE_COMPORT
would not list CH340 port, which is on an Arduino UNO board. (But the same function could list other CH340 port, if it is not on this Arduino). Besides,  this function could not list Bluetooth virtual com ports.
     
     If you would like to use my code, I suggest you use function

BOOL EnumerateComPortSetupAPISetupDiClassGuidsFromNamePort(UINT *pNumber, 
  TCHAR *pPortName, int strMaxLen, TCHAR *pFriendName)

     That is the best one which balances speed and detail; but this one are most complicated in implementation. Otherwise, if you want to implement a function which could list com ports as simple as possible, I recommend use theCreateFilemethod: that is rudimentary, but sufficient.