Add support for wasm32-wasip1 and wasm32-wasip2, remove support for wasm32-wasi (#499)

The `wasm32-wasi` target will be removed in Rust 1.84
(https://blog.rust-lang.org/2024/04/09/updates-to-rusts-wasi-targets.html)
and existing users are encouraged to migrate to either
`wasm32-wasip1`, or `wasm32-wasip2`.

Strictly speaking, this is a breaking change despite affecting only
deprecated target, so it's probably better to release it in `getrandom`
v0.3.

Author: newpavlov

.cargo/config.toml

@@ -1,7 +1,9 @@
 # Allow normal use of "cargo run" and "cargo test" on these wasm32 platforms.
 [target.wasm32-unknown-unknown]
 runner = 'wasm-bindgen-test-runner'
-[target.wasm32-wasi]
+[target.wasm32-wasip1]
+runner = 'wasmtime'
+[target.wasm32-wasip2]
 runner = 'wasmtime'
 
 # Just run on node by default (that's where emscripten is tested)

.github/workflows/tests.yml

@@ -274,21 +274,25 @@ jobs:
         run: cargo test --no-run -Z build-std=std,panic_abort --target=wasm64-unknown-unknown --features=js
 
   wasi-tests:
-    name: WASI Test
+    name: WASI Tests
     runs-on: ubuntu-22.04
     steps:
       - uses: actions/checkout@v4
-      - uses: dtolnay/rust-toolchain@stable
+      - uses: dtolnay/rust-toolchain@master
         with:
-          targets: wasm32-wasi
-      - name: Install precompiled wasmtime
+          toolchain: nightly # TODO: Use stable after 1.82 is released as stable
+          targets: wasm32-wasip1,wasm32-wasip2
+      - name: Install Wasmtime
         run: |
-          VERSION=v2.0.0
+          VERSION=v24.0.0
           URL=https://github.com/bytecodealliance/wasmtime/releases/download/${VERSION}/wasmtime-${VERSION}-x86_64-linux.tar.xz
           wget -O - $URL | tar -xJ --strip-components=1 -C ~/.cargo/bin
           wasmtime --version
       - uses: Swatinem/rust-cache@v2
-      - run: cargo test --target wasm32-wasi
+      - name: WASI 0.1 Test
+        run: cargo test --target wasm32-wasip1
+      - name: WASI 0.2 Test
+        run: cargo test --target wasm32-wasip2
 
   build-tier2:
     name: Tier 2 Build

.github/workflows/workspace.yml

@@ -23,7 +23,7 @@ jobs:
         # Fixed Nigthly version is used to prevent
         # CI failures which are not relevant to PR changes
         # on introduction of new Clippy lints.
-        toolchain: nightly-2024-06-11
+        toolchain: nightly-2024-09-04
         components: clippy,rust-src
     - name: std feature
       run: cargo clippy --features std
@@ -59,8 +59,10 @@ jobs:
       run: cargo clippy -Zbuild-std=core --target x86_64-unknown-redox
     - name: VxWorks (vxworks.rs)
       run: cargo clippy -Zbuild-std=core --target x86_64-wrs-vxworks
-    - name: WASI (wasi.rs)
-      run: cargo clippy -Zbuild-std=core --target wasm32-wasip2
+    - name: WASI preview 1 (wasi.rs)
+      run: cargo clippy -Zbuild-std=core --target wasm32-wasip1
+    - name: WASI preview 2 (wasi.rs)
+      run: cargo clippy -Zbuild-std=core,alloc --target wasm32-wasip2
     - name: Windows 7 (windows7.rs)
       run: cargo clippy -Zbuild-std=core --target x86_64-win7-windows-msvc
     - name: Windows (windows.rs)
@@ -86,7 +88,7 @@ jobs:
       - uses: dtolnay/rust-toolchain@master
         with:
           # We need Nightly for doc_auto_cfg
-          toolchain: nightly-2024-06-11
+          toolchain: nightly-2024-09-04
       - uses: Swatinem/rust-cache@v2
       - name: Generate Docs
         env:

CHANGELOG.md

@@ -8,8 +8,13 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Breaking Changes
 - Update MSRV to 1.38 [#425]
+- Remove support of the `wasm32-wasi` target (use `wasm32-wasip1` or `wasm32-wasip2` instead) [#499]
+
+### Added
+- `wasm32-wasip1` and `wasm32-wasip2` support [#499]
 
 [#425]: https://github.com/rust-random/getrandom/pull/425
+[#499]: https://github.com/rust-random/getrandom/pull/499
 
 ## [0.2.15] - 2024-05-06
 ### Added

Cargo.toml

@@ -21,9 +21,12 @@ core = { version = "1.0", optional = true, package = "rustc-std-workspace-core"
 [target.'cfg(unix)'.dependencies]
 libc = { version = "0.2.154", default-features = false }
 
-[target.'cfg(target_os = "wasi")'.dependencies]
+[target.'cfg(all(target_arch = "wasm32", target_os = "wasi", target_env = "p1"))'.dependencies]
 wasi = { version = "0.11", default-features = false }
 
+[target.'cfg(all(target_arch = "wasm32", target_os = "wasi", target_env = "p2"))'.dependencies]
+wasi = { version = "0.13", default-features = false }
+
 [target.'cfg(all(windows, not(target_vendor = "win7")))'.dependencies]
 windows-targets = "0.52"
 
@@ -46,10 +49,7 @@ js = ["wasm-bindgen", "js-sys"]
 # Feature to enable custom RNG implementations
 custom = []
 # Unstable feature to support being a libstd dependency
-rustc-dep-of-std = [
-  "compiler_builtins",
-  "core",
-]
+rustc-dep-of-std = ["compiler_builtins", "core"]
 # Unstable/test-only feature to run wasm-bindgen tests in a browser
 test-in-browser = []
 
@@ -64,10 +64,10 @@ rustdoc-args = ["--cfg", "docsrs"]
 # workaround for https://github.com/cross-rs/cross/issues/1345
 [package.metadata.cross.target.x86_64-unknown-netbsd]
 pre-build = [
-    "mkdir -p /tmp/netbsd",
-    "curl https://cdn.netbsd.org/pub/NetBSD/NetBSD-9.2/amd64/binary/sets/base.tar.xz -O",
-    "tar -C /tmp/netbsd -xJf base.tar.xz",
-    "cp /tmp/netbsd/usr/lib/libexecinfo.so /usr/local/x86_64-unknown-netbsd/lib",
-    "rm base.tar.xz",
-    "rm -rf /tmp/netbsd",
+  "mkdir -p /tmp/netbsd",
+  "curl https://cdn.netbsd.org/pub/NetBSD/NetBSD-9.2/amd64/binary/sets/base.tar.xz -O",
+  "tar -C /tmp/netbsd -xJf base.tar.xz",
+  "cp /tmp/netbsd/usr/lib/libexecinfo.so /usr/local/x86_64-unknown-netbsd/lib",
+  "rm base.tar.xz",
+  "rm -rf /tmp/netbsd",
 ]

src/lib.rs

@@ -24,7 +24,8 @@
 //! | VxWorks           | `*‑wrs‑vxworks‑*`  | `randABytes` after checking entropy pool initialization with `randSecure`
 //! | ESP-IDF           | `*‑espidf`         | [`esp_fill_random`]
 //! | Emscripten        | `*‑emscripten`     | [`getentropy`][13]
-//! | WASI              | `wasm32‑wasi`      | [`random_get`]
+//! | WASI 0.1    | `wasm32‑wasip1`    | [`random_get`]
+//! | WASI 0.2    | `wasm32‑wasip2`    | [`get-random-u64`]
 //! | Web Browser and Node.js | `wasm*‑*‑unknown` | [`Crypto.getRandomValues`] if available, then [`crypto.randomFillSync`] if on Node.js, see [WebAssembly support]
 //! | SOLID             | `*-kmc-solid_*`    | `SOLID_RNG_SampleRandomBytes`
 //! | Nintendo 3DS      | `*-nintendo-3ds`   | [`getrandom`][18]
@@ -191,7 +192,8 @@
 //! [`cprng_draw`]: https://fuchsia.dev/fuchsia-src/zircon/syscalls/cprng_draw
 //! [`crypto.randomFillSync`]: https://nodejs.org/api/crypto.html#cryptorandomfillsyncbuffer-offset-size
 //! [`esp_fill_random`]: https://docs.espressif.com/projects/esp-idf/en/latest/esp32/api-reference/system/random.html#_CPPv415esp_fill_randomPv6size_t
-//! [`random_get`]: https://github.com/WebAssembly/WASI/blob/main/phases/snapshot/docs.md#-random_getbuf-pointeru8-buf_len-size---errno
+//! [`random_get`]: https://github.com/WebAssembly/WASI/blob/snapshot-01/phases/snapshot/docs.md#-random_getbuf-pointeru8-buf_len-size---errno
+//! [`get-random-u64`]: https://github.com/WebAssembly/WASI/blob/v0.2.1/wasip2/random/random.wit#L23-L28
 //! [WebAssembly support]: #webassembly-support
 //! [`wasm-bindgen`]: https://github.com/rustwasm/wasm-bindgen
 //! [`module`]: https://rustwasm.github.io/wasm-bindgen/reference/attributes/on-js-imports/module.html

src/wasi.rs

@@ -1,9 +1,53 @@
-//! Implementation for WASI
+//! Implementation for WASI (preview 1 and 2)
+//!
+//! `target_env = "p1"` was introduced only in Rust 1.80, so on earlier compiler versions this
+//! code will result in a compilation error.
 use crate::Error;
 use core::mem::MaybeUninit;
-use wasi::random_get;
 
+#[cfg(not(any(target_env = "p1", target_env = "p2")))]
+compile_error!(
+    "Unknown version of WASI (only previews 1 and 2 are supported) \
+    or Rust version older than 1.80 was used"
+);
+
+#[cfg(target_env = "p1")]
 pub fn getrandom_inner(dest: &mut [MaybeUninit<u8>]) -> Result<(), Error> {
-    unsafe { random_get(dest.as_mut_ptr().cast::<u8>(), dest.len()) }
+    unsafe { wasi::random_get(dest.as_mut_ptr().cast::<u8>(), dest.len()) }
         .map_err(|e| Error::from_os_error(e.raw().into()))
 }
+
+#[cfg(target_env = "p2")]
+pub fn getrandom_inner(dest: &mut [MaybeUninit<u8>]) -> Result<(), Error> {
+    use core::ptr::copy_nonoverlapping;
+    use wasi::random::random::get_random_u64;
+
+    let (prefix, chunks, suffix) = unsafe { dest.align_to_mut::<MaybeUninit<u64>>() };
+
+    // We use `get_random_u64` instead of `get_random_bytes` because the latter creates
+    // an allocation due to the Wit IDL [restrictions][0]. This should be fine since
+    // the main use case of `getrandom` is seed generation.
+    //
+    // [0]: https://github.com/WebAssembly/wasi-random/issues/27
+    if !prefix.is_empty() {
+        let val = get_random_u64();
+        let src = (&val as *const u64).cast();
+        unsafe {
+            copy_nonoverlapping(src, prefix.as_mut_ptr(), prefix.len());
+        }
+    }
+
+    for dst in chunks {
+        dst.write(get_random_u64());
+    }
+
+    if !suffix.is_empty() {
+        let val = get_random_u64();
+        let src = (&val as *const u64).cast();
+        unsafe {
+            copy_nonoverlapping(src, suffix.as_mut_ptr(), suffix.len());
+        }
+    }
+
+    Ok(())
+}