From 55d6daf8ee5e9f0de21ed8f49d842b67737a9143 Mon Sep 17 00:00:00 2001
From: Lucian Buzzo <lucian.buzzo@gmail.com>
Date: Sun, 11 Mar 2018 21:39:27 +0000
Subject: [PATCH] Do not mutate options object used in constructor

Connects to #1322

change-type: patch
---
 src/Terminal.test.ts    |  18 ++++--
 src/Terminal.ts         |   3 +-
 src/utils/Clone.test.ts | 137 ++++++++++++++++++++++++++++++++++++++++
 src/utils/Clone.ts      |  28 ++++++++
 4 files changed, 181 insertions(+), 5 deletions(-)
 create mode 100644 src/utils/Clone.test.ts
 create mode 100644 src/utils/Clone.ts

diff --git a/src/Terminal.test.ts b/src/Terminal.test.ts
index d47fbdaf..5a604379 100644
--- a/src/Terminal.test.ts
+++ b/src/Terminal.test.ts
@@ -20,12 +20,13 @@ class TestTerminal extends Terminal {
 
 describe('term.js addons', () => {
   let term: TestTerminal;
+  const termOptions = {
+    cols: INIT_COLS,
+    rows: INIT_ROWS
+  };
 
   beforeEach(() => {
-    term = new TestTerminal({
-      cols: INIT_COLS,
-      rows: INIT_ROWS
-    });
+    term = new TestTerminal(termOptions);
     term.refresh = () => {};
     (<any>term).renderer = new MockRenderer();
     term.viewport = new MockViewport();
@@ -43,6 +44,15 @@ describe('term.js addons', () => {
     };
   });
 
+  it('should not mutate the options parameter', () => {
+    term.setOption('cols', 1000);
+
+    assert.deepEqual(termOptions, {
+      cols: INIT_COLS,
+      rows: INIT_ROWS
+    });
+  });
+
   it('should apply addons with Terminal.applyAddon', () => {
     Terminal.applyAddon(attach);
     // Test that addon was applied successfully, adding attach to Terminal's
diff --git a/src/Terminal.ts b/src/Terminal.ts
index a5841c9d..d1a266b2 100644
--- a/src/Terminal.ts
+++ b/src/Terminal.ts
@@ -40,6 +40,7 @@ import { CharMeasure } from './utils/CharMeasure';
 import * as Browser from './shared/utils/Browser';
 import * as Strings from './Strings';
 import { MouseHelper } from './utils/MouseHelper';
+import { clone } from './utils/Clone';
 import { DEFAULT_BELL_SOUND, SoundManager } from './SoundManager';
 import { DEFAULT_ANSI_COLORS } from './renderer/ColorManager';
 import { MouseZoneManager } from './input/MouseZoneManager';
@@ -245,7 +246,7 @@ export class Terminal extends EventEmitter implements ITerminal, IInputHandlingT
     options: ITerminalOptions = {}
   ) {
     super();
-    this.options = options;
+    this.options = clone(options);
     this._setup();
   }
 
diff --git a/src/utils/Clone.test.ts b/src/utils/Clone.test.ts
new file mode 100644
index 00000000..f5708a9e
--- /dev/null
+++ b/src/utils/Clone.test.ts
@@ -0,0 +1,137 @@
+/**
+ * Copyright (c) 2016 The xterm.js authors. All rights reserved.
+ * @license MIT
+ */
+
+import { assert, expect } from 'chai';
+import { clone } from './Clone';
+
+describe('clone', () => {
+  it('should clone simple objects', () => {
+    const test = {
+      a: 1,
+      b: 2
+    };
+
+    assert.deepEqual(clone(test), { a: 1, b: 2 });
+  });
+
+  it('should clone nested objects', () => {
+    const test = {
+      bar: {
+        a: 1,
+        b: 2,
+        c: {
+          foo: 'bar'
+        }
+      }
+    };
+
+    assert.deepEqual(clone(test), {
+      bar: {
+        a: 1,
+        b: 2,
+        c: {
+          foo: 'bar'
+        }
+      }
+    });
+  });
+
+  it('should clone null values', () => {
+    const test = {
+      a: null
+    };
+
+    assert.deepEqual(clone(test), { a: null });
+  });
+
+  it('should clone array values', () => {
+    const test = {
+      a: [1, 2, 3],
+      b: [1, null, 'test', { foo: 'bar' }]
+    };
+
+    assert.deepEqual(clone(test), {
+      a: [1, 2, 3],
+      b: [1, null, 'test', { foo: 'bar' }]
+    });
+  });
+
+  it('should stop mutation from occuring on the original object', () => {
+    const test = {
+      a: 1,
+      b: 2,
+      c: {
+        foo: 'bar'
+      }
+    };
+
+    const cloned = clone(test);
+
+    test.a = 5;
+    test.c.foo = 'barbaz';
+
+    assert.deepEqual(cloned, {
+      a: 1,
+      b: 2,
+      c: {
+        foo: 'bar'
+      }
+    });
+  });
+
+  it('should clone to a maximum depth of 5 by default', () => {
+    const test = {
+      a: {
+        b: {
+          c: {
+            d: {
+              e: {
+                f: 'foo'
+              }
+            }
+          }
+        }
+      }
+    };
+
+    const cloned = clone(test);
+
+    test.a.b.c.d.e.f = 'bar';
+
+    // The values at a greater depth then 5 should not be cloned
+    assert.equal(cloned.a.b.c.d.e.f, 'bar');
+  });
+
+  it('should allow an optional maximum depth to be set', () => {
+    const test = {
+      a: {
+        b: {
+          c: 'foo'
+        }
+      }
+    };
+
+    const cloned = clone(test, 2);
+
+    test.a.b.c = 'bar';
+
+    // The values at a greater depth then 2 should not be cloned
+    assert.equal(cloned.a.b.c, 'bar');
+  });
+
+  it('should not throw when cloning a recursive reference', () => {
+    const test = {
+      a: {
+        b: {
+          c: {}
+        }
+      }
+    };
+
+    test.a.b.c = test;
+
+    expect(() => clone(test)).to.not.throw();
+  });
+});
diff --git a/src/utils/Clone.ts b/src/utils/Clone.ts
new file mode 100644
index 00000000..b09c0258
--- /dev/null
+++ b/src/utils/Clone.ts
@@ -0,0 +1,28 @@
+/**
+ * Copyright (c) 2016 The xterm.js authors. All rights reserved.
+ * @license MIT
+ */
+
+/*
+ * A simple utility for cloning values
+ */
+export const clone = <T>(val: T, depth: number = 5): T => {
+  if (typeof val !== 'object') {
+    return val;
+  }
+
+  // cloning null always returns null
+  if (val === null) {
+    return null;
+  }
+
+  // If we're cloning an array, use an array as the base, otherwise use an object
+  const clonedObject: any = Array.isArray(val) ? [] : {};
+
+  for (const key in val) {
+    // Recursively clone eack item unless we're at the maximum depth
+    clonedObject[key] = depth <= 1 ? val[key] : clone(val[key], depth - 1);
+  }
+
+  return clonedObject as T;
+};