Don't use Uint8Array when not necessary

Author: daxpedda

.github/workflows/tests.yml

@@ -229,13 +229,29 @@ jobs:
  # run: cargo test
 
  web:
- name: Web
+ name: Web ${{ matrix.rust.description }}
  runs-on: ubuntu-24.04
+ strategy:
+ fail-fast: false
+ matrix:
+ rust:
+ - { version: stable, atomics: false }
+ - {
+ description: with Atomics,
+ atomics: true,
+ version: nightly,
+ components: rust-src,
+ flags: '-Ctarget-feature=+atomics,+bulk-memory',
+ args: '-Zbuild-std=panic_abort,std',
+ }
  env:
  CARGO_BUILD_TARGET: wasm32-unknown-unknown
  steps:
  - uses: actions/checkout@v4
- - uses: dtolnay/rust-toolchain@stable
+ - uses: dtolnay/rust-toolchain@master
+ with:
+ toolchain: ${{ matrix.rust.version }}
+ components: ${{ matrix.rust.components }}
  # - name: Install precompiled wasm-bindgen
  # shell: bash
  # run: |
@@ -251,39 +267,39 @@ jobs:
  - uses: Swatinem/rust-cache@v2
  - name: Test (Node)
  env:
- RUSTFLAGS: -Dwarnings --cfg getrandom_backend="wasm_js"
- run: cargo test --features std
+ RUSTFLAGS: -Dwarnings --cfg getrandom_backend="wasm_js" ${{ matrix.rust.flags }}
+ run: cargo test --features std ${{ matrix.rust.args }}
  - name: Test (Firefox)
  env:
  GECKODRIVER: geckodriver
  WASM_BINDGEN_USE_BROWSER: 1
- RUSTFLAGS: -Dwarnings --cfg getrandom_backend="wasm_js"
- run: cargo test --features std
+ RUSTFLAGS: -Dwarnings --cfg getrandom_backend="wasm_js" ${{ matrix.rust.flags }}
+ run: cargo test --features std ${{ matrix.rust.args }}
  - name: Test (Chrome)
  env:
  CHROMEDRIVER: chromedriver
  WASM_BINDGEN_USE_BROWSER: 1
- RUSTFLAGS: -Dwarnings --cfg getrandom_backend="wasm_js"
- run: cargo test --features std
+ RUSTFLAGS: -Dwarnings --cfg getrandom_backend="wasm_js" ${{ matrix.rust.flags }}
+ run: cargo test --features std ${{ matrix.rust.args }}
  - name: Test (dedicated worker)
  env:
  GECKODRIVER: geckodriver
  WASM_BINDGEN_USE_DEDICATED_WORKER: 1
- RUSTFLAGS: -Dwarnings --cfg getrandom_backend="wasm_js"
- run: cargo test --features std
+ RUSTFLAGS: -Dwarnings --cfg getrandom_backend="wasm_js" ${{ matrix.rust.flags }}
+ run: cargo test --features std ${{ matrix.rust.args }}
  - name: Test (shared worker)
  env:
  GECKODRIVER: geckodriver
  WASM_BINDGEN_USE_SHARED_WORKER: 1
- RUSTFLAGS: -Dwarnings --cfg getrandom_backend="wasm_js"
- run: cargo test --features std
+ RUSTFLAGS: -Dwarnings --cfg getrandom_backend="wasm_js" ${{ matrix.rust.flags }}
+ run: cargo test --features std ${{ matrix.rust.args }}
  - name: Test (service worker)
  env:
  # Firefox doesn't support module service workers and therefor can't import scripts
  CHROMEDRIVER: chromedriver
  WASM_BINDGEN_USE_SERVICE_WORKER: 1
- RUSTFLAGS: -Dwarnings --cfg getrandom_backend="wasm_js"
- run: cargo test --features std
+ RUSTFLAGS: -Dwarnings --cfg getrandom_backend="wasm_js" ${{ matrix.rust.flags }}
+ run: cargo test --features std ${{ matrix.rust.args }}
 
  wasi:
  name: WASI

.github/workflows/workspace.yml

@@ -49,6 +49,10 @@ jobs:
  env:
  RUSTFLAGS: -Dwarnings --cfg getrandom_backend="wasm_js"
  run: cargo clippy -Zbuild-std --target wasm32-unknown-unknown
+ - name: Web WASM with atomics (wasm_js.rs)
+ env:
+ RUSTFLAGS: -Dwarnings --cfg getrandom_backend="wasm_js" -Ctarget-feature=+atomics,+bulk-memory
+ run: cargo clippy -Zbuild-std --target wasm32-unknown-unknown
  - name: Linux (linux_android.rs)
  env:
  RUSTFLAGS: -Dwarnings --cfg getrandom_backend="linux_getrandom"

src/backends/wasm_js.rs

@@ -19,28 +19,36 @@ pub fn fill_inner(dest: &mut [MaybeUninit<u8>]) -> Result<(), Error> {
  CRYPTO.with(|crypto| {
  let crypto = crypto.as_ref().ok_or(Error::WEB_CRYPTO)?;
 
- // getRandomValues does not work with all types of WASM memory,
- // so we initially write to browser memory to avoid exceptions.
- let buf = Uint8Array::new_with_length(CRYPTO_BUFFER_SIZE.into());
- for chunk in dest.chunks_mut(CRYPTO_BUFFER_SIZE.into()) {
- let chunk_len: u32 = chunk
- .len()
- .try_into()
- .expect("chunk length is bounded by CRYPTO_BUFFER_SIZE");
- // The chunk can be smaller than buf's length, so we call to
- // JS to create a smaller view of buf without allocation.
- let sub_buf = if chunk_len == u32::from(CRYPTO_BUFFER_SIZE) {
- buf.clone()
- } else {
- buf.subarray(0, chunk_len)
- };
-
- if crypto.get_random_values(&sub_buf).is_err() {
- return Err(Error::WEB_GET_RANDOM_VALUES);
- }
+ if wasm_bindgen::is_memory_shared() {
+ // getRandomValues does not work with all types of WASM memory,
+ // so we initially write to browser memory to avoid exceptions.
+ let buf = Uint8Array::new_with_length(CRYPTO_BUFFER_SIZE.into());
+ for chunk in dest.chunks_mut(CRYPTO_BUFFER_SIZE.into()) {
+ let chunk_len: u32 = chunk
+ .len()
+ .try_into()
+ .expect("chunk length is bounded by CRYPTO_BUFFER_SIZE");
+ // The chunk can be smaller than buf's length, so we call to
+ // JS to create a smaller view of buf without allocation.
+ let sub_buf = if chunk_len == u32::from(CRYPTO_BUFFER_SIZE) {
+ buf.clone()
+ } else {
+ buf.subarray(0, chunk_len)
+ };
+
+ if crypto.get_random_values(&sub_buf).is_err() {
+ return Err(Error::WEB_GET_RANDOM_VALUES);
+ }
 
- // SAFETY: `sub_buf`'s length is the same length as `chunk`
- unsafe { sub_buf.raw_copy_to_ptr(chunk.as_mut_ptr().cast::<u8>()) };
+ // SAFETY: `sub_buf`'s length is the same length as `chunk`
+ unsafe { sub_buf.raw_copy_to_ptr(chunk.as_mut_ptr().cast::<u8>()) };
+ }
+ } else {
+ for chunk in dest.chunks_mut(CRYPTO_BUFFER_SIZE.into()) {
+ if crypto.get_random_values_ref(chunk).is_err() {
+ return Err(Error::WEB_GET_RANDOM_VALUES);
+ }
+ }
  }
  Ok(())
  })
@@ -56,4 +64,6 @@ extern "C" {
  // Crypto.getRandomValues()
  #[wasm_bindgen(method, js_name = getRandomValues, catch)]
  fn get_random_values(this: &Crypto, buf: &Uint8Array) -> Result<(), JsValue>;
+ #[wasm_bindgen(method, js_name = getRandomValues, catch)]
+ fn get_random_values_ref(this: &Crypto, buf: &mut [MaybeUninit<u8>]) -> Result<(), JsValue>;
 }