feat: works

__wasm/wit-bindgen-sample/engine/getrandom/src/linux_android.rs

@@ -0,0 +1,47 @@
+// Copyright 2018 Developers of the Rand project.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// https://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or https://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+//! Implementation for Linux / Android
+use crate::{
+    util::LazyBool,
+    util_libc::{last_os_error, sys_fill_exact},
+    {use_file, Error},
+};
+
+pub fn getrandom_inner(dest: &mut [u8]) -> Result<(), Error> {
+    // getrandom(2) was introduced in Linux 3.17
+    static HAS_GETRANDOM: LazyBool = LazyBool::new();
+    if HAS_GETRANDOM.unsync_init(is_getrandom_available) {
+        sys_fill_exact(dest, |buf| unsafe {
+            getrandom(buf.as_mut_ptr() as *mut libc::c_void, buf.len(), 0)
+        })
+    } else {
+        use_file::getrandom_inner(dest)
+    }
+}
+
+fn is_getrandom_available() -> bool {
+    let res = unsafe { getrandom(core::ptr::null_mut(), 0, libc::GRND_NONBLOCK) };
+    if res < 0 {
+        match last_os_error().raw_os_error() {
+            Some(libc::ENOSYS) => false, // No kernel support
+            Some(libc::EPERM) => false,  // Blocked by seccomp
+            _ => true,
+        }
+    } else {
+        true
+    }
+}
+
+unsafe fn getrandom(
+    buf: *mut libc::c_void,
+    buflen: libc::size_t,
+    flags: libc::c_uint,
+) -> libc::ssize_t {
+    libc::syscall(libc::SYS_getrandom, buf, buflen, flags) as libc::ssize_t
+}