Detect if file is open locally or over share - c++

Question

I'm trying to check if a file is open in Win32:
bool CheckFileUnlocked(const TCHAR *file)
{
HANDLE fh = ::CreateFile(file, GENERIC_READ, 0, NULL, OPEN_EXISTING, 0, NULL);
if(fh != NULL && fh != INVALID_HANDLE_VALUE) {
return (CloseHandle(fh) == TRUE);
}
return false;
}
I need to be able to distinguish if a file is opened locally, in that case the function must return true against if it is opened from a shared path. The file itself is accessible over network, and is mapped in a shared drive. The function above tries to open file with exclusive access. I tried adding else clause reducing to:
bool CheckFileUnlocked(const TCHAR *file)
{
HANDLE fh = ::CreateFile(file, GENERIC_READ, 0, NULL, OPEN_EXISTING, 0, NULL);
if(fh != NULL && fh != INVALID_HANDLE_VALUE) {
return (CloseHandle(fh) == TRUE);
} else {
fh = ::CreateFile(file, GENERIC_READ, FILE_SHARE_READ, NULL, OPEN_EXISTING, 0, NULL);
if(fh != NULL && fh != INVALID_HANDLE_VALUE) {
return (CloseHandle(fh) == TRUE);
}
}
return false;
}
But I still couldn't figure out if the file was open locally or over network on another system. I also tried LockFileEx() and UnlockFileEx(), but I'm guessing these might be wrong approaches. How do I solve this without actually querying the Application (LibreOffice Writer), assuming it provides API level access to this condition (LO actually provides a popup upon opening said document and allows to open it as ReadOnly, or open a Copy)?

Answer 1

You can try GetFileInformationByHandleEx:
FileRemoteProtocolInfo should return properties of network access, and probably should fail on local files
FileStorageInfo should return properties of the storage, it might fail on network (but need to verify that)