[libc-commits] [libc] [libc] Extend the baremetal I/O vendor ABI (PR #98683)

[Roland McGrath via libc-commits]

frobtech wrote:

> LGTM, I agree with the comments. For return types I think we should generally match what `fread` and `fwrite` do: return the number of characters read/written.

The precise protocol here is already set by the `fopencookie` callbacks' APIs, which have the same return value semantics as their POSIX counterparts.

https://github.com/llvm/llvm-project/pull/98683