Remove wasi dependency completely

Cargo.toml

@@ -21,9 +21,6 @@ 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(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"
 

src/wasi.rs

@@ -11,6 +11,9 @@ compile_error!(
     or Rust version older than 1.80 was used"
 );
 
+#[cfg(not(target_arch = "wasm32"))]
+compile_error!("Currently only 32-bit WASI targets are supported");
+
 #[cfg(target_env = "p1")]
 pub fn getrandom_inner(dest: &mut [MaybeUninit<u8>]) -> Result<(), Error> {
     // This linking is vendored from the wasi crate:
@@ -34,7 +37,19 @@ pub fn getrandom_inner(dest: &mut [MaybeUninit<u8>]) -> Result<(), Error> {
 #[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;
+
+    // Based on the code from the wasi v0.13 crate:
+    // https://docs.rs/wasi/0.13.2+wasi-0.2.1/src/wasi/bindings.rs.html#10845-10860
+    fn get_random_u64() -> u64 {
+        unsafe {
+            #[link(wasm_import_module = "wasi:random/random@0.2.1")]
+            extern "C" {
+                #[link_name = "get-random-u64"]
+                fn wit_import() -> i64;
+            }
+            wit_import() as u64
+        }
+    }
 
     let (prefix, chunks, suffix) = unsafe { dest.align_to_mut::<MaybeUninit<u64>>() };