bjoernager/rust
bjoernager/rust
1
Fork 0
Code Activity

Change WASI's RawFd from u32 to c_int (i32).

Browse source 
WASI previously used `u32` as its `RawFd` type, since its "file descriptors"
are unsigned table indices, and there's no fundamental reason why WASI can't
have more than 2^31 handles.

However, this creates myriad little incompability problems with code
that also supports Unix platforms, where `RawFd` is `c_int`. While WASI
isn't a Unix, it often shares code with Unix, and this difference made
such shared code inconvenient. #87329 is the most recent example of such
code.

So, switch WASI to use `c_int`, which is `i32`. This will mean that code
intending to support WASI should ideally avoid assuming that negative file
descriptors are invalid, even though POSIX itself says that file descriptors
are never negative.

This is a breaking change, but `RawFd` is considerd an experimental
feature in [the documentation].

[the documentation]: https://doc.rust-lang.org/stable/std/os/wasi/io/type.RawFd.html
This commit is contained in:
Dan Gohman 2021-08-13 08:58:05 -07:00
parent 8df945c471
commit 35de5c9b35
5 changed files with 83 additions and 54 deletions
Download patch file Download diff file Expand all files Collapse all files

21
library/std/src/os/wasi/io.rs
View file

@ -6,11 +6,18 @@
use crate::fs;
use crate::io;
use crate::net;
use crate::os::raw;
use crate::sys;
use crate::sys_common::{AsInner, FromInner, IntoInner};
/// Raw file descriptors.
pub type RawFd = u32;
///
/// This has type `c_int` to ease compatibility with code that also compiles on
/// Unix configurations, however unlike Unix and POSIX, in WASI negative file
/// descriptors are valid. Only `-1` is reserved for indicating errors. Code
/// intending to be portable across Unix platforms and WASI should avoid
/// assuming that negative file descriptors are invalid.
pub type RawFd = raw::c_int;
/// A trait to extract the raw WASI file descriptor from an underlying
/// object.
@ -161,41 +168,41 @@ impl IntoRawFd for fs::File {
impl AsRawFd for io::Stdin {
#[inline]
fn as_raw_fd(&self) -> RawFd {
libc::STDIN_FILENO as RawFd
libc::STDIN_FILENO
}
}
impl AsRawFd for io::Stdout {
#[inline]
fn as_raw_fd(&self) -> RawFd {
libc::STDOUT_FILENO as RawFd
libc::STDOUT_FILENO
}
}
impl AsRawFd for io::Stderr {
#[inline]
fn as_raw_fd(&self) -> RawFd {
libc::STDERR_FILENO as RawFd
libc::STDERR_FILENO
}
}
impl<'a> AsRawFd for io::StdinLock<'a> {
#[inline]
fn as_raw_fd(&self) -> RawFd {
libc::STDIN_FILENO as RawFd
libc::STDIN_FILENO
}
}
impl<'a> AsRawFd for io::StdoutLock<'a> {
#[inline]
fn as_raw_fd(&self) -> RawFd {
libc::STDOUT_FILENO as RawFd
libc::STDOUT_FILENO
}
}
impl<'a> AsRawFd for io::StderrLock<'a> {
#[inline]
fn as_raw_fd(&self) -> RawFd {
libc::STDERR_FILENO as RawFd
libc::STDERR_FILENO
}
}