Drop USB interface before reset

[dingari]

This is required on (at least) macOS, as the usb_reset method will fail while there are interfaces claimed.

This should fix #6

Relies on dfu-rs/dfu-core#31

[cecton]

@sjoerdsimons is this PR okay for you?

Notable changes:

• added nix files (useful for some, doesn't hurt)
• adapted the code to drop the interface after the usb_reset()

[sjoerdsimons]

I'd rather not include the nix files; I don't use nix, so that'll just go unmaintained.. I don't think crates should have distro specific configuration in them as that's a very slippery slope.

As it stands this commit still makes dfu-nusb use a forked dfu-core, so that should be dropped before merging. Also should do a semver bump as the api is changed.

The code i'd need to further review (as always end of the year is hectic, so i'm slow).. But from a quick look the change to the usb_reset signature seems awkward, simply taking self would end up a lot more elegant (and a much smaller delta).

[sjoerdsimons]

@cecton btw just quickly looking at dfu-core ; looks like 0.9.2 is a semver break (changing the type of arguments); That should have been 0.10 instead

[dingari]

Totally understand wrt to the nix devshell. I always meant to remove them before PR-ing. I'll fixup the commit and re-push.

As it stands this commit still makes dfu-nusb use a forked dfu-core, so that should be dropped before merging.

Oh, yeah! Totally. I'll wait for a new dfu-core semver bump and fix that.

Also should do a semver bump as the api is changed.

I figured a maintainer would do that before issuing a new release?

[dingari]

But from a quick look the change to the usb_reset signature seems awkward, simply taking self would end up a lot more elegant (and a much smaller delta).

Sure, I'll be happy to make that change to dfu-core (consuming self), and updating this PR to reflect that.

[dingari]

@sjoerdsimons making usb_reset consume self just shifts the partial-move into the DfuASync / DfuSync impls. As download calls usb_reset.

error[E0507]: cannot move out of `self.io` which is behind a mutable reference
   --> /Users/genki/development/dfu-core/src/asynchronous.rs:239:21
    |
239 |                     self.io.usb_reset().await?;
    |                     ^^^^^^^ ----------- `self.io` moved due to this method call
    |                     |
    |                     move occurs because `self.io` has type `IO`, which does not implement the `Copy` trait
    |
note: `DfuAsyncIo::usb_reset` takes ownership of the receiver `self`, which moves `self.io`
   --> /Users/genki/development/dfu-core/src/asynchronous.rs:40:18
    |
40  |     fn usb_reset(self) -> impl Future<Output = Result<Self::Reset, Self::Error>> + Send;
    |                  ^^^^
help: if `IO` implemented `Clone`, you could clone the value
   --> /Users/genki/development/dfu-core/src/asynchronous.rs:157:6
    |
157 | impl<IO, E> DfuASync<IO, E>
    |      ^^ consider constraining this type parameter with `Clone`
...
239 |                     self.io.usb_reset().await?;
    |                     ------- you could clone this value

error[E0507]: cannot move out of `self.io` which is behind a mutable reference
   --> /Users/genki/development/dfu-core/src/sync.rs:173:21
    |
173 |                     self.io.usb_reset()?;
    |                     ^^^^^^^ ----------- `self.io` moved due to this method call
    |                     |
    |                     move occurs because `self.io` has type `IO`, which does not implement the `Copy` trait
    |
note: `DfuIo::usb_reset` takes ownership of the receiver `self`, which moves `self.io`
   --> /Users/genki/development/dfu-core/src/lib.rs:107:18
    |
107 |     fn usb_reset(self) -> Result<Self::Reset, Self::Error>;
    |                  ^^^^
help: if `IO` implemented `Clone`, you could clone the value
   --> /Users/genki/development/dfu-core/src/sync.rs:95:6
    |
95  | impl<IO, E> DfuSync<IO, E>
    |      ^^ consider constraining this type parameter with `Clone`
...
173 |                     self.io.usb_reset()?;
    |                     ------- you could clone this value

For more information about this error, try `rustc --explain E0507`.
error: could not compile `dfu-core` (lib) due to 2 previous errors

So, honestly, I think the way this PR does it is just OK. I could move the interface-unwrapping in a fn to avoid code duplication.

[cecton]

Oops you're right

It's yanked and I released 0.10.

[cecton]

@sjoerdsimons making usb_reset consume self just shifts the partial-move into the DfuASync / DfuSync impls. As download calls usb_reset.

Ah yes that was the issue. Using a state machine has its limitations. The IO object must stay alive.

[cecton]

Seems all good to me. Only waiting on @sjoerdsimons feedback 😇