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Update to wasi 0.11#253

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Merged
josephlr merged 3 commits into from
Apr 15, 2022
Merged

Update to wasi 0.11 #253

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4588b54
Update to wasi 0.11
Thomasdezeeuw Mar 19, 2022
3487d64
Use libc::strerror to get the error message on wasi
Thomasdezeeuw Mar 26, 2022
523b443
Remove libc dependency for WASI
Thomasdezeeuw Mar 29, 2022
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2 changes: 1 addition & 1 deletion Cargo.toml
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Expand Up@@ -21,7 +21,7 @@ core = { version = "1.0", optional = true, package = "rustc-std-workspace-core"
libc = { version = "0.2.120", default-features = false }

[target.'cfg(target_os = "wasi")'.dependencies]
wasi = "0.10"
wasi = "0.11"

[target.'cfg(all(target_arch = "wasm32", target_os = "unknown"))'.dependencies]
wasm-bindgen = { version = "0.2.62", default-features = false, optional = true }
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4 changes: 0 additions & 4 deletions src/error.rs
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Expand Up@@ -109,10 +109,6 @@ cfg_if! {
let idx = buf.iter().position(|&b| b == 0).unwrap_or(n);
core::str::from_utf8(&buf[..idx]).ok()
}
} else if #[cfg(target_os = "wasi")] {
fn os_err(errno: i32, _buf: &mut [u8]) -> Option<wasi::Error> {
wasi::Error::from_raw_error(errno as _)
}
} else {
fn os_err(_errno: i32, _buf: &mut [u8]) -> Option<&str> {
None
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12 changes: 4 additions & 8 deletions src/wasi.rs
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Expand Up@@ -9,15 +9,11 @@
//! Implementation for WASI
use crate::Error;
use core::num::NonZeroU32;
use wasi::random_get;
use wasi::wasi_snapshot_preview1::random_get;

@josephlrjosephlrMar 26, 2022

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Why not just use wasi::random_get?

@ThomasdezeeuwThomasdezeeuwMar 26, 2022

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Because the new Errno from wasi, which replaced Error, can actually hold 0. Errno::as_raw returns u16, which may be zero, thus invalidating the previous code calling NonZeroU32::new_unchecked. However handling zero ourselves ensures we can call NonZeroU32::new_unchecked again.

@josephlrjosephlrMar 26, 2022

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But it won't actually be zero if the function returns Err, so it seems fine.

@newpavlovnewpavlovMar 26, 2022•
edited
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It would mean that soundness of our code relies on an implementation detail of wasi. I am not sure we can rely on it, even though it's a very reasonable assumption.

@ThomasdezeeuwThomasdezeeuwMar 26, 2022

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It would mean that soundness of our code relies on an implementation detail of wasi. I am not sure we can rely on it, even though it's a very reasonable assumption.

This is the exact reason I decided to switch.


pub fn getrandom_inner(dest: &mut [u8]) -> Result<(), Error> {
unsafe {
random_get(dest.as_mut_ptr(), dest.len()).map_err(|e: wasi::Error| {
// convert wasi's Error into getrandom's NonZeroU32 error
// SAFETY: `wasi::Error` is `NonZeroU16` internally, so `e.raw_error()`
// will never return 0
NonZeroU32::new_unchecked(e.raw_error() as u32).into()
})
match unsafe { random_get(dest.as_mut_ptr() as i32, dest.len() as i32) } {
0 => Ok(()),
err => Err(unsafe { NonZeroU32::new_unchecked(err as u32) }.into()),
}
}