readline: improve robustness against prototype mutation

PR-URL: #45614
Reviewed-By: James M Snell <jasnell@gmail.com>

lib/internal/readline/interface.js

@@ -22,13 +22,10 @@ const {
   NumberIsNaN,
   ObjectSetPrototypeOf,
   RegExpPrototypeExec,
-  RegExpPrototypeSymbolReplace,
-  RegExpPrototypeSymbolSplit,
   StringPrototypeCodePointAt,
   StringPrototypeEndsWith,
   StringPrototypeRepeat,
   StringPrototypeSlice,
-  StringPrototypeSplit,
   StringPrototypeStartsWith,
   StringPrototypeTrim,
   Symbol,
@@ -77,7 +74,7 @@ const kHistorySize = 30;
 const kMaxUndoRedoStackSize = 2048;
 const kMincrlfDelay = 100;
 // \r\n, \n, or \r followed by something other than \n
-const lineEnding = /\r?\n|\r(?!\n)/;
+const lineEnding = /\r?\n|\r(?!\n)/g;
 
 const kLineObjectStream = Symbol('line object stream');
 const kQuestionCancel = Symbol('kQuestionCancel');
@@ -590,31 +587,40 @@ class Interface extends InterfaceConstructor {
       this[kSawReturnAt] &&
       DateNow() - this[kSawReturnAt] <= this.crlfDelay
     ) {
-      string = RegExpPrototypeSymbolReplace(/^\n/, string, '');
+      if (StringPrototypeCodePointAt(string) === 10) string = StringPrototypeSlice(string, 1);
       this[kSawReturnAt] = 0;
     }
 
     // Run test() on the new string chunk, not on the entire line buffer.
-    const newPartContainsEnding = RegExpPrototypeExec(lineEnding, string) !== null;
-
-    if (this[kLine_buffer]) {
-      string = this[kLine_buffer] + string;
-      this[kLine_buffer] = null;
-    }
-    if (newPartContainsEnding) {
+    let newPartContainsEnding = RegExpPrototypeExec(lineEnding, string);
+    if (newPartContainsEnding !== null) {
+      if (this[kLine_buffer]) {
+        string = this[kLine_buffer] + string;
+        this[kLine_buffer] = null;
+        newPartContainsEnding = RegExpPrototypeExec(lineEnding, string);
+      }
       this[kSawReturnAt] = StringPrototypeEndsWith(string, '\r') ?
         DateNow() :
         0;
 
-      // Got one or more newlines; process into "line" events
-      const lines = StringPrototypeSplit(string, lineEnding);
+      const indexes = [0, newPartContainsEnding.index, lineEnding.lastIndex];
+      let nextMatch;
+      while ((nextMatch = RegExpPrototypeExec(lineEnding, string)) !== null) {
+        ArrayPrototypePush(indexes, nextMatch.index, lineEnding.lastIndex);
+      }
+      const lastIndex = indexes.length - 1;
       // Either '' or (conceivably) the unfinished portion of the next line
-      string = ArrayPrototypePop(lines);
-      this[kLine_buffer] = string;
-      for (let n = 0; n < lines.length; n++) this[kOnLine](lines[n]);
+      this[kLine_buffer] = StringPrototypeSlice(string, indexes[lastIndex]);
+      for (let i = 1; i < lastIndex; i += 2) {
+        this[kOnLine](StringPrototypeSlice(string, indexes[i - 1], indexes[i]));
+      }
     } else if (string) {
       // No newlines this time, save what we have for next time
-      this[kLine_buffer] = string;
+      if (this[kLine_buffer]) {
+        this[kLine_buffer] += string;
+      } else {
+        this[kLine_buffer] = string;
+      }
     }
   }
 
@@ -1322,12 +1328,18 @@ class Interface extends InterfaceConstructor {
         // falls through
         default:
           if (typeof s === 'string' && s) {
-            const lines = RegExpPrototypeSymbolSplit(/\r\n|\n|\r/, s);
-            for (let i = 0, len = lines.length; i < len; i++) {
-              if (i > 0) {
+            let nextMatch = RegExpPrototypeExec(lineEnding, s);
+            if (nextMatch !== null) {
+              this[kInsertString](StringPrototypeSlice(s, 0, nextMatch.index));
+              let { lastIndex } = lineEnding;
+              while ((nextMatch = RegExpPrototypeExec(lineEnding, s)) !== null) {
                 this[kLine]();
+                this[kInsertString](StringPrototypeSlice(s, lastIndex, nextMatch.index));
+                ({ lastIndex } = lineEnding);
               }
-              this[kInsertString](lines[i]);
+              if (lastIndex === s.length) this[kLine]();
+            } else {
+              this[kInsertString](s);
             }
           }
       }