Add support for getentropy in d8

Author: hoodmane

src/lib/libwasi.js

@@ -567,6 +567,9 @@ var WasiLibrary = {
 
   // random.h
 
+#if ENVIRONMENT_MAY_BE_SHELL
+  $initRandomFill__deps: ['$base64Decode'],
+#endif
   $initRandomFill: () => {
 #if ENVIRONMENT_MAY_BE_NODE && MIN_NODE_VERSION < 190000
     // This block is not needed on v19+ since crypto.getRandomValues is builtin
@@ -576,6 +579,18 @@ var WasiLibrary = {
     }
 #endif // ENVIRONMENT_MAY_BE_NODE
 
+#if ENVIRONMENT_MAY_BE_SHELL
+    if (ENVIRONMENT_IS_SHELL) {
+      return (view) => {
+        if (!os.system) {
+          throw new Error('randomFill not supported on d8 unless --enable-os-system is passed');
+        }
+        const b64 = os.system('sh', ['-c', `head -c${view.byteLength} /dev/urandom | base64 --wrap=0`]);
+        view.set(base64Decode(b64));
+      };
+    }
+#endif
+
 #if SHARED_MEMORY
     // like with most Web APIs, we can't use Web Crypto API directly on shared memory,
     // so we need to create an intermediate buffer and copy it to the destination

src/modules.mjs

@@ -78,7 +78,7 @@ function calculateLibraries() {
     libraries.push('libmemoryprofiler.js');
   }
 
-  if (SUPPORT_BASE64_EMBEDDING) {
+  if (SUPPORT_BASE64_EMBEDDING || ENVIRONMENT_MAY_BE_SHELL) {
     libraries.push('libbase64.js');
   }
 

test/test_other.py

@@ -16016,3 +16016,20 @@ def test_locate_file_abspath_esm(self, args):
                  output_suffix='.mjs',
                  emcc_args=['--pre-js', 'pre.js',
                             '--extern-post-js', test_file('modularize_post_js.js')] + args)
+  @requires_v8
+  def test_getentropy_d8(self):
+    create_file('main.c', '''
+      #include "assert.h"
+      #include <unistd.h>
+
+      int main() {
+        char buf[100];
+        assert(getentropy(buf, sizeof(buf)) == 0);
+        return 0;
+      }
+    ''')
+
+    msg = 'randomFill not supported on d8 unless --enable-os-system is passed'
+    self.do_runf('main.c', msg, assert_returncode=1)
+    self.v8_args += ['--enable-os-system']
+    self.do_runf('main.c')