lib: add primordials.SafeStringIterator

lib/internal/per_context/primordials.js

@@ -232,6 +232,9 @@ primordials.SafeWeakSet = makeSafe(
 // Refs: https://tc39.es/ecma262/#sec-%typedarray%-intrinsic-object
 [
   { name: 'TypedArray', original: Reflect.getPrototypeOf(Uint8Array) },
+  { name: 'StringIterator', original: {
+    prototype: Reflect.getPrototypeOf(String.prototype[Symbol.iterator]()),
+  } },
 ].forEach(({ name, original }) => {
   primordials[name] = original;
   // The static %TypedArray% methods require a valid `this`, but can't be bound,
@@ -240,5 +243,10 @@ primordials.SafeWeakSet = makeSafe(
   copyPrototype(original.prototype, primordials, `${name}Prototype`);
 });
 
+primordials.SafeStringIterator = createSafeIterator(
+  primordials.StringPrototypeSymbolIterator,
+  primordials.StringIteratorPrototypeNext
+);
+
 Object.setPrototypeOf(primordials, null);
 Object.freeze(primordials);

lib/internal/repl/utils.js

@@ -9,6 +9,7 @@ const {
   MathMin,
   RegExpPrototypeTest,
   SafeSet,
+  SafeStringIterator,
   StringPrototypeEndsWith,
   StringPrototypeIndexOf,
   StringPrototypeLastIndexOf,
@@ -425,7 +426,7 @@ function setupPreview(repl, contextSymbol, bufferSymbol, active) {
           getStringWidth(inspected) > maxColumns) {
         maxColumns -= 4 + (repl.useColors ? 0 : 3);
         let res = '';
-        for (const char of inspected) {
+        for (const char of new SafeStringIterator(inspected)) {
           maxColumns -= getStringWidth(char);
           if (maxColumns < 0)
             break;

lib/internal/source_map/prepare_stack_trace.js

@@ -9,6 +9,7 @@ const {
   StringPrototypeSlice,
   StringPrototypeSplit,
   StringPrototypeStartsWith,
+  SafeStringIterator,
 } = primordials;
 
 let debug = require('internal/util/debuglog').debuglog('source_map', (fn) => {
@@ -144,7 +145,8 @@ function getErrorSource(
   // Display ^ in appropriate position, regardless of whether tabs or
   // spaces are used:
   let prefix = '';
-  for (const character of StringPrototypeSlice(line, 0, originalColumn + 1)) {
+  for (const character of new SafeStringIterator(
+    StringPrototypeSlice(line, 0, originalColumn + 1))) {
     prefix += (character === '\t') ? '\t' :
       StringPrototypeRepeat(' ', getStringWidth(character));
   }

lib/internal/util/inspect.js

@@ -42,6 +42,7 @@ const {
   ReflectApply,
   RegExp,
   RegExpPrototypeToString,
+  SafeStringIterator,
   Set,
   SetPrototypeGetSize,
   SetPrototypeValues,
@@ -2005,7 +2006,7 @@ if (internalBinding('config').hasIntl) {
     if (removeControlChars)
       str = stripVTControlCharacters(str);
     str = str.normalize('NFC');
-    for (const char of str) {
+    for (const char of new SafeStringIterator(str)) {
       const code = char.codePointAt(0);
       if (isFullWidthCodePoint(code)) {
         width += 2;

lib/readline.js

@@ -59,6 +59,7 @@ const {
   StringPrototypeTrim,
   Symbol,
   SymbolAsyncIterator,
+  SafeStringIterator,
 } = primordials;
 
 const {
@@ -760,7 +761,7 @@ Interface.prototype._getDisplayPos = function(str) {
   const col = this.columns;
   let rows = 0;
   str = stripVTControlCharacters(str);
-  for (const char of str) {
+  for (const char of new SafeStringIterator(str)) {
     if (char === '\n') {
       // Rows must be incremented by 1 even if offset = 0 or col = +Infinity.
       rows += MathCeil(offset / col) || 1;
@@ -1181,7 +1182,7 @@ function emitKeypressEvents(stream, iface = {}) {
         iface.isCompletionEnabled = false;
 
         let length = 0;
-        for (const character of string) {
+        for (const character of new SafeStringIterator(string)) {
           length += character.length;
           if (length === string.length) {
             iface.isCompletionEnabled = true;