On Sun, May 23, 2021 at 7:57 PM Matthew Flatt <mfl...@cs.utah.edu> wrote:
> At Sun, 23 May 2021 14:57:42 +0000, Sage Gerard wrote: > > Is there a cross-VM way to pass an arbitrary input port to the C > > runtime (e.g. via open-input-bytes), such that the C runtime can read > > bytes on its own? > > No, not unless you know that the port's implementation is sufficiently > constrained. In general, reading from a port can involve thread > switches and synchronization, and those are not allowed in callbacks > from foreign libraries. > Off hand, I think some some version of "sanitizing" an arbitrary port for use from C is used by: - `racket/system` (here <https://github.com/racket/racket/blob/448b77a6629c68659e1360fbe9f9e1ecea078f9c/racket/collects/racket/system.rkt#L98-L114> and here <https://github.com/racket/racket/blob/448b77a6629c68659e1360fbe9f9e1ecea078f9c/racket/collects/racket/system.rkt#L173-L193>), where the implementation comes from `racket/private/streams`; - `racket/draw`, for the various parts of Cairo that can read from or write to ports, in `racket/draw/unsafe/callback` (and maybe something similar in `racket/draw/private/write-bytes`?); and - `readline`, which uses callbacks rather than creating file-stream ports. Would it make sense to expose some part of this functionality as a new primitive? (I'm not familiar with all of the constraints in these use-cases: maybe they're different enough that the answer is "no".) -Philip -- You received this message because you are subscribed to the Google Groups "Racket Users" group. To unsubscribe from this group and stop receiving emails from it, send an email to racket-users+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/racket-users/010001799bd5ab46-d39f83a5-bb2d-49e5-8ce2-3315307742ac-000000%40email.amazonses.com.
