fix: correct ArrayBuffer validation in arrayBufferToBase64

Makefile

@@ -73,6 +73,7 @@ endif
 			echo "Got: $$error_msg"; \
 			exit 1; \
 		fi
+		@extism call examples/base64.wasm greet --wasi --input="Benjamin" --log-level=debug
 
 compile-examples: cli
 		cd examples/react && npm install && npm run build && cd ../..
@@ -81,6 +82,7 @@ compile-examples: cli
 		./target/release/extism-js examples/host_funcs/script.js -i examples/host_funcs/script.d.ts -o examples/host_funcs.wasm
 		./target/release/extism-js examples/exports/script.js -i examples/exports/script.d.ts -o examples/exports.wasm
 		./target/release/extism-js examples/exception/script.js -i examples/exception/script.d.ts -o examples/exception.wasm
+		./target/release/extism-js examples/base64/script.js -i examples/base64/script.d.ts -o examples/base64.wasm
 
 kitchen: 
 	cd examples/kitchen-sink && npm install && npm run build && cd ../..

crates/core/src/globals.rs

@@ -187,37 +187,24 @@ fn build_host_object<'js>(this: Ctx<'js>) -> anyhow::Result<Object<'js>> {
         this.clone(),
         MutFn::new(move |cx: Ctx<'js>, args: Rest<Value<'js>>| {
             let data = args.first().unwrap();
-            if !data.is_array() {
-                return Err::<_, rquickjs::Error>(to_js_error(
-                    cx.clone(),
-                    anyhow!("Expect an array buffer"),
-                ));
-            }
 
-            let Some(data) = data.as_array() else {
-                return Err::<_, rquickjs::Error>(to_js_error(
-                    cx.clone(),
-                    anyhow!("Could not convert arg to array buffer"),
-                ));
-            };
+            let data = data
+                .as_object()
+                .ok_or_else(|| to_js_error(cx.clone(), anyhow!("Expected an ArrayBuffer")))?;
 
             if !data.is_array_buffer() {
-                return Err::<_, rquickjs::Error>(to_js_error(
-                    cx.clone(),
-                    anyhow!("Expected an array buffer"),
-                ));
+                return Err(to_js_error(cx.clone(), anyhow!("Expected an ArrayBuffer")));
             }
 
-            let Some(data) = data.as_array_buffer() else {
-                return Err::<_, rquickjs::Error>(to_js_error(
-                    cx.clone(),
-                    anyhow!("Could not convert the array to an arrayBuffer"),
-                ));
-            };
-            use base64::prelude::*;
             let bytes = data
+                .as_array_buffer()
+                .expect("Should be able to cast data as an array buffer")
                 .as_bytes()
-                .ok_or_else(|| to_js_error(cx.clone(), anyhow!("Could not convert to bytes")))?;
+                .ok_or_else(|| {
+                    to_js_error(cx.clone(), anyhow!("Could not get bytes from ArrayBuffer"))
+                })?;
+
+            use base64::prelude::*;
             let as_string = BASE64_STANDARD.encode(bytes);
 
             rquickjs::String::from_str(cx.clone(), &as_string)

examples/base64/jsconfig.json

@@ -0,0 +1,8 @@
+{
+  "compilerOptions": {
+    "lib": [],
+    "types": [
+      "../../crates/core/src/prelude"
+    ]
+  }
+}

examples/base64/script.d.ts

@@ -0,0 +1,3 @@
+declare module "main" {
+  export function greet(): I32;
+}

examples/base64/script.js

@@ -0,0 +1,22 @@
+function greet() {
+  try {
+    const base64String = "SGVsbG8g8J+MjSBXb3JsZCHwn4yN";
+
+    console.log('decoding string:', base64String);
+
+    const decodedBuffer = Host.base64ToArrayBuffer(base64String);
+    const decodedString = new TextDecoder().decode(decodedBuffer);
+
+    console.log('decoded string:', decodedString);
+
+    const encodedBuffer = Host.arrayBufferToBase64(decodedBuffer);
+
+    console.log('encoded string:', encodedBuffer);
+
+    Host.outputString(`Hello, ${Host.inputString()}`)
+  } catch (error) {
+    console.error('Base64 test failed, Error:', JSON.stringify(error));
+  }
+}
+
+module.exports = { greet };

examples/kitchen-sink/src/index.ts

@@ -34,5 +34,6 @@ export function greet() {
   const mem = Memory.fromString("Hello, " + body.data + " " + configLastName);
   Host.outputString(mem.readString()); // TODO: ideally have a way to output memory directly
   mem.free();
+
   return 0;
 }