Issue 5535 - Replace our module system with webpack

webpack_runner.js

Index: webpack_runner.js
diff --git a/webpack_runner.js b/webpack_runner.js
new file mode 100644
index 0000000000000000000000000000000000000000..b04016265abc109cbb9597c2bb5fdc8fc10c5742
--- /dev/null
+++ b/webpack_runner.js
@@ -0,0 +1,150 @@
+/*
+ * This file is part of Adblock Plus <https://adblockplus.org/>,
+ * Copyright (C) 2006-present eyeo GmbH
+ *
+ * Adblock Plus is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 3 as
+ * published by the Free Software Foundation.
+ *
+ * Adblock Plus is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with Adblock Plus.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+"use strict";
+
+const path = require("path");
+const process = require("process");
+
+const MemoryFS = require("memory-fs");
+const webpack = require("webpack");
+
+// We read the configuration from STDIN rather than as an argument to improve
+// the output on error. Otherwise the (fairly huge) configuration is printed
+// along with the actual error message.
+let inputChunks = [];
+process.stdin.setEncoding("utf-8");
+process.stdin.on("data", chunk => { inputChunks.push(chunk); });
+process.stdin.on("end", () =>
+{
+  let {bundles, extension_path,
+       info_module, resolve_paths} = JSON.parse(inputChunks.join(""));
+
+  // The contents of the info module is passed to us as a string from the Python
+  // packager and we pass it through to our custom loader now so it is available
+  // at bundle time.
+  require("./info-loader").setInfoModule(info_module);
+
+  // Since the cost of starting Node.js and loading all the modules is hugely
+  // larger than actually producing bundles we avoid paying it multiple times,
+  // instead producing all the bundles in one go.
+  let options = [];
+  for (let {bundle_name, entry_points} of bundles)
+  {
+    options.push({
+      context: extension_path,
+      devtool: "source-map",
+      module: {
+        rules: [{
+          include: path.join(__dirname, "info.js"),
+          use: ["info-loader"]
+        }]
+      },
+      entry: entry_points,
+      output: {
+        path: "/",
+        filename: bundle_name
+      },
+      resolve: {
+        modules: resolve_paths,
+        alias: {
+          // To use our custom loader for the info module we must first set up
+          // an alias to a file that exists.
+          info$: path.join(__dirname, "info.js"),
+          // Prevent builtin Node.js modules from being used instead of our own
+          // when the names clash. Once relative paths are used this won't be
+          // necessary.
+          url$: "url.js",
+          events$: "events.js",
+          punycode$: "punycode.js"
+        },
+        plugins: [
+          function()
+          {
+            // Our old module system in packagerChrome.py used to prefix
+            // module names with the name of their parent directory and an
+            // underscore - but only when that directory wasn't called
+            // "lib". This plugin is for backwards compatability, but can
+            // be removed once use of that deprecated syntax has been
+            // replaced.
+            this.plugin("described-resolve", (request, callback) =>
+            {
+              let target = request.request;
+
+              let prefixIndex = target.indexOf("_");
+              if (prefixIndex == -1)
+                return callback();
+
+              let prefix = target.substring(0, prefixIndex);
+              if (prefix == "lib")
+                return callback();
+
+              let fixedTarget = path.join(prefix,
+                                           target.substring(prefixIndex + 1));
+              return this.doResolve(
+                "resolve", Object.assign({}, request, {request: fixedTarget}),
+                "Changed prefixed path using legacy buildtools syntax from " +
+                target + " to " + fixedTarget,
+                callback
+              );
+            });
+          }
+        ]
+      },
+      resolveLoader: {
+        modules: [path.resolve(__dirname)]
+      }
+    });
+  }
+
+  // Based on this example
+  // https://webpack.js.org/api/node/#custom-file-systems
+  let memoryFS = new MemoryFS();
+  let webpackCompiler = webpack(options);
+
+  webpackCompiler.outputFileSystem = memoryFS;
+  webpackCompiler.run((err, stats) =>
+  {
+    // Error handling is based on this example
+    // https://webpack.js.org/api/node/#error-handling
+    if (err)
+    {
+      let reason = err.stack || err;
+      if (err.details)
+        reason += "\n" + err.details;
+      throw new Error(reason);
+    }
+    else if (stats.hasErrors())
+      throw new Error(stats.toJson().errors.join("\n"));
+    else
+    {
+      let files = {};
+
+      for (let config of options)
+      {
+        let filepath = path.join(config.output.path, config.output.filename);
+        let relativeFilepath = path.relative("/", filepath);

[kzar, 2017/10/12 11:57:28]

These few lines are the only difference from the previous review (except for
being rebased e.g. the omitted package-lock.json) file. See
https://issues.adblockplus.org/ticket/5535 and
https://codereview.adblockplus.org/29573821/ for more context.

+        files[relativeFilepath] = memoryFS.readFileSync(filepath, "utf-8");
+        files[relativeFilepath + ".map"] = memoryFS.readFileSync(
+          filepath + ".map", "utf-8"
+        );
+      }
+
+      console.log(JSON.stringify(files));
+    }
+  });
+});