Rebase Windows support onto RawHandle instead of File

[adamreichold]

This is a follow-up to #30 and allows mapping anything that implements AsRawHandle including the types of async-std.

I took the Win32 API usage from Rust's standard library and thereby adjusted the existing structure declarations to match.

I did test this under Wine using the async-std cat example as in #30 but I have to admit to not feeling particularly confident on this as Win32 is not a platform I regularly target.

[RazrFalcon]

Nice! Should I merge #30 first?

[RazrFalcon]

Adding more raw winapi calls is not great, but looks like there is no other way.

[adamreichold]

Nice! Should I merge #30 first?

Yes, #30 is simple and safe while this is bound to get more involved.

Adding more raw winapi calls is not great, but looks like there is no other way.

Well, I could actually use fs::File::from_raw_handle to turn the given handle back into an instance of fs::File. This way I could use basically the same API calls as now, but I am not sure if fs::File makes any extra assumptions on the handle (that the raw Win32 API calls do not make) and personally, I would say that roundabout way would be quite confusing.

A different maintainability/clean-up change I could follow-up with would be to replace the manual FFI declarations by usage of the winapi crate? But I am not sure how downstream consumers (most importantly rustc) would like that.

[RazrFalcon]

The whole reason this fork exist is to remove the winapi crate dependency, so no. The current code if fine.

[RazrFalcon]

Thanks again for your work! Do you plan any other changes or can I publish a new release?

[adamreichold]

Thanks again for your work! Do you plan any other changes or can I publish a new release?

I am currently pondering whether the assertions in the Drop impls for MmapInner should be removed in the line with the discussion at rust-lang/lang-team#97 I am currently looking into standard library types and they all seem to ignore being unable to close/free/release resources during drop, e.g. https://doc.rust-lang.org/stable/src/std/io/buffered/bufwriter.rs.html#669-674 What do you think?