Resolve symlinks inside 'node_modules'

Author: aleclarson

lib/require-hook.js

@@ -18,12 +18,75 @@ module.exports = function requireHook (opts) {
   var hasSetMain = false;
   var currentWrapFile = null;
 
+  function resolveSymlink (filePath) {
+    while (fs.existsSync(filePath) && fs.lstatSync(filePath).isSymbolicLink()) {
+      filePath = fs.readlinkSync(filePath);
+    }
+    return filePath;
+  }
+
+  // Searches each parent directory for a 'package.json'
+  function resolvePackage (pkgRoot) {
+    while (pkgRoot !== path.sep) {
+      pkgPath = path.join(pkgRoot, 'package.json');
+      if (fs.existsSync(pkgPath)) {
+        return resolveSymlink(pkgRoot);
+      }
+      pkgRoot = path.dirname(pkgRoot);
+    }
+    return null;
+  }
+
+  // Searches each 'node_modules' directory
+  // for a module (including the global root)
+  function resolveModule (request, parent) {
+    var pkgRoot = resolvePackage(
+      parent.id === '.' ?
+        process.cwd() :
+        path.dirname(parent.id)
+    );
+    if (pkgRoot) {
+      var depName = request.split(path.sep)[0];
+      var depPath = resolveSymlink(
+        path.join(pkgRoot, 'node_modules', depName)
+      );
+      if (fs.existsSync(depPath)) {
+        return path.join(
+          depPath,
+          path.relative(depName, request)
+        );
+      }
+
+      //
+      // Search each directory in $NODE_PATH
+      //
+      var nodePaths = process.env.NODE_PATH.split(':');
+      for (var i = 0; i < nodePaths.length; i++) {
+        pkgRoot = nodePaths[i];
+        if (fs.existsSync(pkgRoot) && fs.statSync(pkgRoot).isDirectory()) {
+          depPath = resolveSymlink(
+            path.join(pkgRoot, depName)
+          );
+          if (fs.existsSync(depPath)) {
+            return path.join(
+              depPath,
+              path.relative(depName, request)
+            );
+          }
+        }
+      }
+    }
+    return request;
+  }
+
   var loadModule = Module._load;
   Module._load = function(request, parent, isMain) {
     if (request[0] === '.') {
       if (parent.id === '.') {
         request = path.resolve(process.cwd(), request);
       }
+    } else if (request[0] !== path.sep) {
+      request = resolveModule(request, parent);
     }
     return loadModule(request, parent, isMain);
   };