reg.cpp: check for guid format

[Artoria2e5]

If this complies this should fix #171

[DDoSolitary]

Thanks. Some suggestions:

• Pass the string as const ref (crwstr)
• Also skip if the string is too long (code == ERROR_MORE_DATA)
• Add a corresponding unit test in test_reg.cpp

[Artoria2e5]

I think I should really grab a compiler before I do all that...

[Artoria2e5]

Oh by the way, I don't think the thing needs a length check. The calling buffer is supposed to only be that long anyways, and I don't find the regex particularly complex.

(Yes I am deleting War Thunder high-res assets and googling MSVC community)

[DDoSolitary]

I mean, as Microsoft is adding other "non-distro" subkeys under the Lxss key, it's possible that they add something whose name is longer than a GUID. In that case, the current code will simply throw an exception and exit immediately

LxRunOffline/src/lib/reg.cpp

Line 151 in 9ad2554

else if (code) throw lro_error::from_win32(err_msg::err_enum_key, { reg_base_path }, code);

This is not very ideal and we need to make it skip the subkey instead.

[Artoria2e5]

many thanks for cleaning my shit up…