fix(napi): JsStringUtf8 memory leak (#2911)

crates/napi/src/js_values/string/mod.rs

@@ -109,13 +109,11 @@ impl<'env> JsString<'env> {
       )
     })?;
 
-    // respect '\0' with js string, for example: `let hello = [a,'\0',b,'\0',c].join('')`
-    let mut result = mem::ManuallyDrop::new(result);
-    let buf_ptr = result.as_mut_ptr();
-    let bytes = unsafe { std::slice::from_raw_parts(buf_ptr.cast(), written_char_count) };
+    mem::forget(result);
+
     Ok(JsStringUtf8 {
       inner: self,
-      buf: bytes,
+      buf: unsafe { Vec::from_raw_parts(buf_ptr.cast(), written_char_count, written_char_count) },
     })
   }
 
@@ -161,7 +159,9 @@ impl<'env> JsString<'env> {
     Ok(JsStringLatin1 {
       inner: self,
       buf: unsafe { std::slice::from_raw_parts(buf_ptr.cast(), written_char_count) },
-      _inner_buf: vec![],
+      _inner_buf: unsafe {
+        Vec::from_raw_parts(buf_ptr.cast(), written_char_count, written_char_count)
+      },
     })
   }
 }

crates/napi/src/js_values/string/utf8.rs

@@ -1,20 +1,21 @@
 use std::convert::TryFrom;
 use std::str;
 
-use crate::{bindgen_prelude::ToNapiValue, sys, Error, JsString, Result};
+use crate::{bindgen_prelude::ToNapiValue, sys, Error, JsString, Result, Status};
 
 pub struct JsStringUtf8<'env> {
   pub(crate) inner: JsString<'env>,
-  pub(crate) buf: &'env [u8],
+  pub(crate) buf: Vec<u8>,
 }
 
 impl<'env> JsStringUtf8<'env> {
   pub fn as_str(&self) -> Result<&str> {
-    Ok(unsafe { str::from_utf8_unchecked(self.buf) })
+    str::from_utf8(self.buf.as_slice())
+      .map_err(|err| Error::new(Status::InvalidArg, err.to_string()))
   }
 
   pub fn as_slice(&self) -> &[u8] {
-    self.buf
+    self.buf.as_slice()
   }
 
   pub fn len(&self) -> usize {

examples/napi/__tests__/__snapshots__/values.spec.ts.md

@@ -832,6 +832,8 @@ Generated by [AVA](https://avajs.dev).
     ␊
     export declare function indexSetToRust(set: Set<string>): void␊
     ␊
+    export declare function intoUtf8(s: string): string␊
+    ␊
     export declare function jsErrorCallback(value: unknown): Array<Error>␊
     ␊
     /** default enum values are continuos i32s start from 0 */␊

examples/napi/__tests__/values.spec.ts

@@ -286,6 +286,7 @@ import {
   arrayParams,
   indexSetToRust,
   indexSetToJs,
+  intoUtf8,
 } from '../index.cjs'
 // import other stuff in `#[napi(module_exports)]`
 import nativeAddon from '../index.cjs'
@@ -337,6 +338,7 @@ test('string', (t) => {
   t.is(createExternalLatin1String(), 'External Latin1')
   t.is(createStaticLatin1String(), 'Static Latin1 string')
   t.is(createStaticUtf16String(), 'Static UTF16')
+  t.is(intoUtf8('Hello'), 'Hello')
 })
 
 test('JsStringLatin1::from_external tests', (t) => {

examples/napi/example.wasi-browser.js

@@ -283,6 +283,7 @@ export const i8ArrayToArray = __napiModule.exports.i8ArrayToArray
 export const indexmapPassthrough = __napiModule.exports.indexmapPassthrough
 export const indexSetToJs = __napiModule.exports.indexSetToJs
 export const indexSetToRust = __napiModule.exports.indexSetToRust
+export const intoUtf8 = __napiModule.exports.intoUtf8
 export const jsErrorCallback = __napiModule.exports.jsErrorCallback
 export const Kind = __napiModule.exports.Kind
 export const KindInValidate = __napiModule.exports.KindInValidate

examples/napi/example.wasi.cjs

@@ -328,6 +328,7 @@ module.exports.i8ArrayToArray = __napiModule.exports.i8ArrayToArray
 module.exports.indexmapPassthrough = __napiModule.exports.indexmapPassthrough
 module.exports.indexSetToJs = __napiModule.exports.indexSetToJs
 module.exports.indexSetToRust = __napiModule.exports.indexSetToRust
+module.exports.intoUtf8 = __napiModule.exports.intoUtf8
 module.exports.jsErrorCallback = __napiModule.exports.jsErrorCallback
 module.exports.Kind = __napiModule.exports.Kind
 module.exports.KindInValidate = __napiModule.exports.KindInValidate

examples/napi/index.cjs

@@ -728,6 +728,7 @@ module.exports.i8ArrayToArray = nativeBinding.i8ArrayToArray
 module.exports.indexmapPassthrough = nativeBinding.indexmapPassthrough
 module.exports.indexSetToJs = nativeBinding.indexSetToJs
 module.exports.indexSetToRust = nativeBinding.indexSetToRust
+module.exports.intoUtf8 = nativeBinding.intoUtf8
 module.exports.jsErrorCallback = nativeBinding.jsErrorCallback
 module.exports.Kind = nativeBinding.Kind
 module.exports.KindInValidate = nativeBinding.KindInValidate

examples/napi/index.d.cts

@@ -793,6 +793,8 @@ export declare function indexSetToJs(): Set<string>
 
 export declare function indexSetToRust(set: Set<string>): void
 
+export declare function intoUtf8(s: string): string
+
 export declare function jsErrorCallback(value: unknown): Array<Error>
 
 /** default enum values are continuos i32s start from 0 */

examples/napi/src/string.rs

@@ -1,4 +1,4 @@
-use napi::{bindgen_prelude::*, JsString, JsStringLatin1, JsStringUtf16};
+use napi::{bindgen_prelude::*, JsString, JsStringLatin1, JsStringUtf16, JsStringUtf8};
 
 #[napi(object)]
 pub struct Latin1MethodsResult {
@@ -40,6 +40,11 @@ pub fn return_c_string() -> RawCString {
   RawCString::new(mock_c_string_ptr, NAPI_AUTO_LENGTH)
 }
 
+#[napi]
+pub fn into_utf8(s: JsString) -> Result<JsStringUtf8> {
+  s.into_utf8()
+}
+
 #[napi]
 /// Function to test escaped quotes in comments.
 /// This comment contains escaped quotes: \\"g+sx\\" and should not break JSON parsing.