Add meaningful error when executing bower link on windows when user is not elevated.

#472

lib/commands/link.js

@@ -1,12 +1,10 @@
-var fs = require('graceful-fs');
 var path = require('path');
-var mkdirp = require('mkdirp');
 var rimraf = require('rimraf');
 var mout = require('mout');
 var Q = require('q');
 var Logger = require('bower-logger');
 var Project = require('../core/Project');
-var createError = require('../util/createError');
+var createLink = require('../util/createLink');
 var cli = require('../util/cli');
 var defaultConfig = require('../config');
 
@@ -72,30 +70,6 @@ function linkTo(name, localName, config) {
     return logger;
 }
 
-function createLink(src, dst) {
-    var dstDir = path.dirname(dst);
-
-    // Create directory
-    return Q.nfcall(mkdirp, dstDir)
-    // Check if source exists
-    .then(function () {
-        return Q.nfcall(fs.lstat, src)
-        .fail(function (error) {
-            if (error.code === 'ENOENT') {
-                throw createError('Failed to create link to ' + path.basename(src), 'ENOENT', {
-                    details: src + ' doest not exists or points to a non-existent package'
-                });
-            }
-
-            throw error;
-        });
-    })
-    // Create symlink
-    .then(function () {
-        return Q.nfcall(fs.symlink, src, dst, 'dir');
-    });
-}
-
 // -------------------
 
 var link = {

lib/util/createLink.js

@@ -0,0 +1,44 @@
+var fs = require('fs');
+var path = require('path');
+var Q = require('q');
+var mkdirp = require('mkdirp');
+var createError = require('./createError');
+
+var isWin = process.platform === 'win32';
+
+function createLink(src, dst, type) {
+    var dstDir = path.dirname(dst);
+
+    // Create directory
+    return Q.nfcall(mkdirp, dstDir)
+    // Check if source exists
+    .then(function () {
+        return Q.nfcall(fs.stat, src)
+        .fail(function (error) {
+            if (error.code === 'ENOENT') {
+                throw createError('Failed to create link to ' + path.basename(src), 'ENOENT', {
+                    details: src + ' doest not exists or points to a non-existent file'
+                });
+            }
+
+            throw error;
+        });
+    })
+    // Create symlink
+    .then(function (stat) {
+        type = type || (stat.isDirectory() ? 'dir' : 'file');
+
+        return Q.nfcall(fs.symlink, src, dst, type)
+        .fail(function (err) {
+            if (isWin && err.code === 'EPERM') {
+                throw createError('Unable to create link to ' + path.basename(src), err.code, {
+                    details: err.message + '\n\nTry running this command in an elevated terminal (run as root/administrator).'
+                });
+            }
+
+            throw err;
+        });
+    });
+}
+
+module.exports = createLink;