On Thu, 2023-03-09 at 15:04 +0900, Asahi Lina wrote:
On 08/03/2023 02.34, Björn Roy Baron wrote:
+ // SAFETY: This is just the ioctl argument, which hopefully has the right type + // (we've done our best checking the size).
In the rust tree there is the ReadableFromBytes [1] trait which indicates that it is safe to read arbitrary bytes into the type. Maybe you could add it as bound on the argument type when it lands in rust-next? This way you can't end up with for example a struct containing a bool with the byte value 2, which is UB.
There's actually a much bigger story here, because that trait isn't really very useful without a way to auto-derive it. I need the same kind of guarantee for all the GPU firmware structs...
There's one using only declarative macros [1] and one using proc macros [2]. And then, since ioctl arguments are declared in C UAPI header files, we need a way to be able to derive those traits for them... which I guess means bindgen changes?
It'd be cool to be able to auto-verify that uAPI structs are all tightly packed and use the right subset of types. Maybe not possible this iteration but it'd be cool to see in future. I'd like to see it for C as well, ideally.
~Faith