Handling of Windows system file status broken since 1.79.0

[MarcelRaad]

Since commit 97722a3, calls like these fail on Windows 10:
boost::filesystem::is_directory(L"C:\\System Volume Information")
boost::filesystem::is_symlink(L"C:\\DumpStack.log")

This is because CreateFileW now fails with ERROR_ACCESS_DENIED, while the previously used GetFileAttributesW succeeded.

[Lastique]

Note that std::filesystem::symlink_status also returns "Access denied" for "C:\System Volume Information". std::filesystem::status succeeds. I'm not sure I like this kind of inconsistency.

[MarcelRaad]

I can confirm that the patch works great. Thanks a lot!

[TMeindl]

FYI: This does still not work when the directory is on a usb device; i.e. when a USB Device is for example mounted on drive H and has a valid directory with the name "source":
boost::filesystem::is_directory("H:\source") --> false
std::filesystem::is_directory("H:\source") --> true

[Lastique]

What filesystem is H:? What Windows version? Can you debug this case?

Assuming that you're not passing an error_code and there is no exception, WinAPI calls don't fail in your case, so this is not the same issue as the one that was originally reported here. Please open a new issue with all additional information you find.

[TMeindl]

Ah, sorry, there where other changes in the operations.cpp file; I just used this patch for testing. I can confirm that with boost version 1.80 boost::filesystem::is_directory() works as expected.