CreateFileMapping for Directory - c++

Question

I have this function which gives the full file name(path) from the file handle. The only problem is CreateFileMapping fails for directory handles. Is there a workaround for it?
I get the handle using NtCreateFile()
ULONG status = NtCreatefile(&f, GENERIC_ALL, &oa, iosb, NULL, FILE_ATTRIBUTE_NORMAL, FILE_SHARE_READ | FILE_SHARE_WRITE, FILE_OPEN, FILE_OPEN_BY_FILE_ID , NULL, 0);
printf("status: %X, handle: %x\n", status, f);
AND
BOOL CHouseKeeper::GetFileNameFromHandle(HANDLE hFile)
{
BOOL bSuccess = FALSE;
TCHAR pszFilename[MAX_PATH+1];
HANDLE hFileMap;
// Get the file size.
DWORD dwFileSizeHi = 0;
DWORD dwFileSizeLo = GetFileSize(hFile, &dwFileSizeHi);
if( dwFileSizeLo == 0 && dwFileSizeHi == 0 )
{
_tprintf(TEXT("Cannot map a file with a length of zero.\n"));
return FALSE;
}
// Create a file mapping object.
//It fails here if a directory handle is passed, it returns 0
hFileMap = CreateFileMapping(hFile,
NULL,
PAGE_READONLY,
0,
1,
NULL);
if (hFileMap)
{
// Create a file mapping to get the file name.
void* pMem = MapViewOfFile(hFileMap, FILE_MAP_READ, 0, 0, 1);
if (pMem)
{
if (GetMappedFileName (GetCurrentProcess(),
pMem,
pszFilename,
MAX_PATH))
{
// Translate path with device name to drive letters.
TCHAR szTemp[BUFSIZE];
szTemp[0] = '\0';
if (GetLogicalDriveStrings(BUFSIZE-1, szTemp))
{
TCHAR szName[MAX_PATH];
TCHAR szDrive[3] = TEXT(" :");
BOOL bFound = FALSE;
TCHAR* p = szTemp;
do
{
// Copy the drive letter to the template string
*szDrive = *p;
// Look up each device name
if (QueryDosDevice(szDrive, szName, MAX_PATH))
{
size_t uNameLen = _tcslen(szName);
if (uNameLen < MAX_PATH)
{
bFound = _tcsnicmp(pszFilename, szName, uNameLen) == 0
&& *(pszFilename + uNameLen) == _T('\\');
if (bFound)
{
// Reconstruct pszFilename using szTempFile
// Replace device path with DOS path
TCHAR szTempFile[MAX_PATH];
StringCchPrintf(szTempFile,
MAX_PATH,
TEXT("%s%s"),
szDrive,
pszFilename+uNameLen);
StringCchCopyN(pszFilename, MAX_PATH+1, szTempFile, _tcslen(szTempFile));
}
}
}
// Go to the next NULL character.
while (*p++);
} while (!bFound && *p); // end of string
}
}
bSuccess = TRUE;
UnmapViewOfFile(pMem);
}
CloseHandle(hFileMap);
}else {
wcout<<GetLastError()<<endl;
}
_tprintf(TEXT("File name is %s\n"), pszFilename);
return(bSuccess);
}

Answer 1

You can use NtQueryInformationFile with FileNameInformation to retrieve the name associated with a file handle.