fix error messages for readonly

Fail more cleanly when run from a readonly files system without setting readOnly true.

red.js

@@ -101,8 +101,18 @@ if (parsedArgs.settings) {
             var settingsStat = fs.statSync(defaultSettings);
             if (settingsStat.mtime.getTime() <= settingsStat.ctime.getTime()) {
                 // Default settings file has not been modified - safe to copy
-                fs.copySync(defaultSettings,userSettingsFile);
-                settingsFile = userSettingsFile;
+                try {
+                    fs.copySync(defaultSettings,userSettingsFile);
+                    settingsFile = userSettingsFile;
+                }
+                catch (err) {
+                    console.log("Failed to copy settings file to "+userSettingsFile);
+                    console.log("Error: "+err.toString());
+                    if (err.code == "EACCES") {
+                        console.log("You may need to set readOnly: true, in settings.js");
+                    }
+                    process.exit(1);
+                }
             } else {
                 // Use default settings.js as it has been modified
                 settingsFile = defaultSettings;

red/runtime/locales/en-US/runtime.json

@@ -142,6 +142,7 @@
             "restore": "Restoring __type__ file backup : __path__",
             "restore-fail": "Restoring __type__ file backup failed : __message__",
             "fsync-fail": "Flushing file __path__ to disk failed : __message__",
+            "fwrite-fail": "Writing backup file __path__ to disk failed : __message__",
             "projects": {
                 "changing-project": "Setting active project : __project__",
                 "active-project": "Active project : __project__",

red/runtime/storage/localfilesystem/util.js

@@ -81,7 +81,11 @@ module.exports = {
      writeFile: function(path,content,backupPath) {
          if (backupPath) {
             if (fs.existsSync(path)) {
-                fs.renameSync(path,backupPath);
+                try {
+                    fs.renameSync(path,backupPath);
+                } catch(e) {
+                    log.warn(log._("storage.localfilesystem.fwrite-fail",{path:path, message:e.toString()}));
+                }
             }
         }
         return when.promise(function(resolve,reject) {