From 7f4049d379f5083634ab63e59c51eebaabdc4b7a Mon Sep 17 00:00:00 2001
From: Jasper De Moor <jdemo@live.be>
Date: Sun, 24 Jun 2018 08:06:12 +0200
Subject: [PATCH] Fix bugs related to watching symlinks (#1408)

---
 src/Bundler.js                                | 10 +++++---
 src/utils/fs.js                               | 11 +++++++-
 .../commonjs-with-symlinks/local.js           |  2 ++
 .../commonjs-with-symlinks/src/index.js       |  5 ++++
 .../src/symlinked_local.js                    |  1 +
 test/watcher.js                               | 25 +++++++++++++++++++
 6 files changed, 50 insertions(+), 4 deletions(-)
 create mode 100644 test/integration/commonjs-with-symlinks/local.js
 create mode 100644 test/integration/commonjs-with-symlinks/src/index.js
 create mode 120000 test/integration/commonjs-with-symlinks/src/symlinked_local.js

diff --git a/src/Bundler.js b/src/Bundler.js
index 5698f5efc52..1bc7351ef44 100644
--- a/src/Bundler.js
+++ b/src/Bundler.js
@@ -56,6 +56,7 @@ class Bundler extends EventEmitter {
     this.pending = false;
     this.loadedAssets = new Map();
     this.watchedAssets = new Map();
+
     this.farm = null;
     this.watcher = null;
     this.hmr = null;
@@ -391,24 +392,27 @@ class Bundler extends EventEmitter {
     return asset;
   }
 
-  watch(path, asset) {
+  async watch(path, asset) {
     if (!this.watcher) {
       return;
     }
 
+    path = await fs.realpath(path);
+
     if (!this.watchedAssets.has(path)) {
       this.watcher.watch(path);
       this.watchedAssets.set(path, new Set());
     }
-
     this.watchedAssets.get(path).add(asset);
   }
 
-  unwatch(path, asset) {
+  async unwatch(path, asset) {
     if (!this.watchedAssets.has(path)) {
       return;
     }
 
+    path = await fs.realpath(path);
+
     let watched = this.watchedAssets.get(path);
     watched.delete(asset);
 
diff --git a/src/utils/fs.js b/src/utils/fs.js
index a301f0eadce..830efa410aa 100644
--- a/src/utils/fs.js
+++ b/src/utils/fs.js
@@ -7,7 +7,16 @@ exports.writeFile = promisify(fs.writeFile);
 exports.stat = promisify(fs.stat);
 exports.readdir = promisify(fs.readdir);
 exports.unlink = promisify(fs.unlink);
-exports.realpath = promisify(fs.realpath);
+exports.realpath = async function(path) {
+  const realpath = promisify(fs.realpath);
+  try {
+    path = await realpath(path);
+  } catch (e) {
+    // do nothing
+  }
+  return path;
+};
+exports.lstat = promisify(fs.lstat);
 
 exports.exists = function(filename) {
   return new Promise(resolve => {
diff --git a/test/integration/commonjs-with-symlinks/local.js b/test/integration/commonjs-with-symlinks/local.js
new file mode 100644
index 00000000000..59aa6ffd125
--- /dev/null
+++ b/test/integration/commonjs-with-symlinks/local.js
@@ -0,0 +1,2 @@
+exports.a = 1;
+exports.b = 2;
diff --git a/test/integration/commonjs-with-symlinks/src/index.js b/test/integration/commonjs-with-symlinks/src/index.js
new file mode 100644
index 00000000000..29505d1b818
--- /dev/null
+++ b/test/integration/commonjs-with-symlinks/src/index.js
@@ -0,0 +1,5 @@
+var local = require('./symlinked_local');
+
+module.exports = function () {
+  return local.a + local.b;
+};
diff --git a/test/integration/commonjs-with-symlinks/src/symlinked_local.js b/test/integration/commonjs-with-symlinks/src/symlinked_local.js
new file mode 120000
index 00000000000..ea037a11afd
--- /dev/null
+++ b/test/integration/commonjs-with-symlinks/src/symlinked_local.js
@@ -0,0 +1 @@
+../local.js
\ No newline at end of file
diff --git a/test/watcher.js b/test/watcher.js
index 9b9019034b9..f5de60da3d3 100644
--- a/test/watcher.js
+++ b/test/watcher.js
@@ -253,4 +253,29 @@ describe('watcher', function() {
     assert(file.includes('function Foo'));
     assert(file.includes('function Bar'));
   });
+
+  it('should rebuild if the file behind a symlink changes', async function() {
+    await ncp(
+      __dirname + '/integration/commonjs-with-symlinks/',
+      __dirname + '/input'
+    );
+
+    b = bundler(__dirname + '/input/src/index.js', {
+      watch: true
+    });
+
+    let bundle = await b.bundle();
+    let output = await run(bundle);
+
+    assert.equal(output(), 3);
+
+    await fs.writeFile(
+      __dirname + '/input/local.js',
+      'exports.a = 5; exports.b = 5;'
+    );
+
+    bundle = await nextBundle(b);
+    output = await run(bundle);
+    assert.equal(output(), 10);
+  });
 });