Check unsupported file name for fopen - c++

Question

I'm trying to open a file to treat it later. My problem is that if my file name is not ANSI (Arabic, Hindi...) fopen_s and fopen refuse to open it and give me an Invalid argument error. I can't use CreateFile() to do that so I thought to check either my file name is supported by fopen or not(try to open it) and create a temporary file instead:
QString fileN=QString::fromWCharArray(fname);
QFileInfo file(DIRPath+"/"+fileN);
bool Supported=true;
if(file.exists()) {
QString temp;
char* Fname=(char*)malloc(260*sizeof(char));
strcpy(Fname,(QString(DIRPath+"/"+fileN).toStdString()).c_str());
FILE* Filedesc;
errno_t err=fopen_s(&Filedesc,Fname,"rb");
if(Filedesc!=NULL) {
qDebug()<<"\nfile opened ";
fclose(Filedesc);
} else if(err==22) {
qDebug()<<"\nfail to open file error 22: Invalid argument";
temp=QString(DIRPath+"/Temp"+QString::number(nb));
Supported=false;
} else qDebug()<<"\nfail to open file error"<<GetLastError()<<"errno"<<errno<<"strerrno"<<strerror(errno);
Fname=NULL;
free(Fname);
...
My question is: can anyone clarify for me the UNICODE/ANSI confusion? Am I safe so far or are there more precautions to consider? Is there a safer way to check if the given name is not ANSI?
Thank you in advance, any help will be appreciated.
EDIT 1
I tried this but in vain : CreateFile() return an INVALID_HANDLE_VALUE and GetLastError() return 0
//WCHAR fname[]=L"D:/أحدالأنشطة.txt";
char* name="D:/أحدالأنشطة.txt";
wchar_t* nameW=(wchar_t*)malloc(sizeof(wchar_t)*17);
qDebug()<<"s :"<<mbstowcs(nameW,name,17);
//QString path=QString::fromWCharArray(fname,17);
//QString path=QString::fromLatin1(name,17);
HANDLE fileHandle = CreateFile( nameW, // file to open
GENERIC_READ, // open for reading
FILE_SHARE_READ, // share for reading
NULL, // default security
OPEN_EXISTING, // existing file only
FILE_ATTRIBUTE_NORMAL, // normal file
NULL);
if (fileHandle == INVALID_HANDLE_VALUE)
{
qDebug()<<"CreateFile failed!\n"<<GetLastError();
nameW=NULL;
free(nameW);
return 2;
}else
qDebug()<<"CreateFile succeeded!\n";
int fd = _open_osfhandle((intptr_t) fileHandle, _O_RDONLY);
FILE* fstr = _fdopen(fd, "r");
QFile indirect;
if (!indirect.open(fstr, QIODevice::ReadOnly))
qDebug()<<"QFile open against file descriptor failed!\n";
else
{
qDebug()<<"QFile open against file descriptor succeeded!\n";
indirect.close();
}
// This will fail
QFile direct(path);
if (!direct.open(QIODevice::ReadOnly))
qDebug()<<"QFile open of filename directly failed!\n";
else
{
qDebug()<<"QFile open of filename directly succeeded!\n";
direct.close();
}
nameW=NULL;
free(nameW);
EDIT 2
QString fname(QFile::decodeName("D:/أحدالأنشطة.txt"));
QFile qFile(fname);
bool b=qFile.open(QIODevice::ReadOnly);
if(b)
{
FILE* filedesc = fdopen(qFile.handle(), "rb");
if(filedesc!=NULL)
{
char* nb=(char*)malloc(2*sizeof(char));
qDebug()<<"opened ";
size_t size=fread(nb,sizeof(char),2,filedesc);
fclose(filedesc);
qDebug()<<"filedesc closed size "<<size<<"nb "<<QString::fromAscii(nb,2);
nb=NULL;
free(nb);
}else qDebug()<<"filedesc failed error"<<strerror(errno);
}else
qDebug()<<"qFile failed error"<<strerror(errno);

Answer 1

You should probably use QFile to open the file, and then pass QFile::handle() to your C function. In the C code you would then use fdopen() to associate a FILE* stream to the file descriptor. Note that the mode you use in fdopen() should be compatible with the mode you used in QFile::open(). For example:
void c_func(int fd)
{
FILE* file = fdopen(fd, "rb");
// ...
}