1 files changed, 117 insertions, 0 deletions
diff --git a/toolkit/components/processsingleton/ContentProcessSingleton.js b/toolkit/components/processsingleton/ContentProcessSingleton.js
new file mode 100644
index 000000000..72f5803e1
--- /dev/null
+++ b/toolkit/components/processsingleton/ContentProcessSingleton.js
@@ -0,0 +1,117 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+const Cu = Components.utils;
+const Ci = Components.interfaces;
+
+Cu.import("resource://gre/modules/Services.jsm");
+Cu.import("resource://gre/modules/XPCOMUtils.jsm");
+
+XPCOMUtils.defineLazyServiceGetter(this, "cpmm",
+                                   "@mozilla.org/childprocessmessagemanager;1",
+                                   "nsIMessageSender");
+
+/*
+ * The message manager has an upper limit on message sizes that it can
+ * reliably forward to the parent so we limit the size of console log event
+ * messages that we forward here. The web console is local and receives the
+ * full console message, but addons subscribed to console event messages
+ * in the parent receive the truncated version. Due to fragmentation,
+ * messages as small as 1MB have resulted in IPC allocation failures on
+ * 32-bit platforms. To limit IPC allocation sizes, console.log messages
+ * with arguments with total size > MSG_MGR_CONSOLE_MAX_SIZE (bytes) have
+ * their arguments completely truncated. MSG_MGR_CONSOLE_VAR_SIZE is an
+ * approximation of how much space (in bytes) a JS non-string variable will
+ * require in the manager's implementation. For strings, we use 2 bytes per
+ * char. The console message URI and function name are limited to
+ * MSG_MGR_CONSOLE_INFO_MAX characters. We don't attempt to calculate
+ * the exact amount of space the message manager implementation will require
+ * for a given message so this is imperfect.
+ */
+const MSG_MGR_CONSOLE_MAX_SIZE = 1024 * 1024; // 1MB
+const MSG_MGR_CONSOLE_VAR_SIZE = 8;
+const MSG_MGR_CONSOLE_INFO_MAX = 1024;
+
+function ContentProcessSingleton() {}
+ContentProcessSingleton.prototype = {
+  classID: Components.ID("{ca2a8470-45c7-11e4-916c-0800200c9a66}"),
+  QueryInterface: XPCOMUtils.generateQI([Ci.nsIObserver,
+                                         Ci.nsISupportsWeakReference]),
+
+  observe: function(subject, topic, data) {
+    switch (topic) {
+    case "app-startup": {
+      Services.obs.addObserver(this, "console-api-log-event", false);
+      Services.obs.addObserver(this, "xpcom-shutdown", false);
+      cpmm.addMessageListener("DevTools:InitDebuggerServer", this);
+      break;
+    }
+    case "console-api-log-event": {
+      let consoleMsg = subject.wrappedJSObject;
+
+      let msgData = {
+        level: consoleMsg.level,
+        filename: consoleMsg.filename.substring(0, MSG_MGR_CONSOLE_INFO_MAX),
+        lineNumber: consoleMsg.lineNumber,
+        functionName: consoleMsg.functionName.substring(0,
+          MSG_MGR_CONSOLE_INFO_MAX),
+        timeStamp: consoleMsg.timeStamp,
+        arguments: [],
+      };
+
+      // We can't send objects over the message manager, so we sanitize
+      // them out, replacing those arguments with "<unavailable>".
+      let unavailString = "<unavailable>";
+      let unavailStringLength = unavailString.length * 2; // 2-bytes per char
+
+      // When the sum of argument sizes reaches MSG_MGR_CONSOLE_MAX_SIZE,
+      // replace all arguments with "<truncated>".
+      let totalArgLength = 0;
+
+      // Walk through the arguments, checking the type and size.
+      for (let arg of consoleMsg.arguments) {
+        if ((typeof arg == "object" || typeof arg == "function") &&
+            arg !== null) {
+          arg = unavailString;
+          totalArgLength += unavailStringLength;
+        } else if (typeof arg == "string") {
+          totalArgLength += arg.length * 2; // 2-bytes per char
+        } else {
+          totalArgLength += MSG_MGR_CONSOLE_VAR_SIZE;
+        }
+
+        if (totalArgLength <= MSG_MGR_CONSOLE_MAX_SIZE) {
+          msgData.arguments.push(arg);
+        } else {
+          // arguments take up too much space
+          msgData.arguments = ["<truncated>"];
+          break;
+        }
+      }
+
+      cpmm.sendAsyncMessage("Console:Log", msgData);
+      break;
+    }
+
+    case "xpcom-shutdown":
+      Services.obs.removeObserver(this, "console-api-log-event");
+      Services.obs.removeObserver(this, "xpcom-shutdown");
+      cpmm.removeMessageListener("DevTools:InitDebuggerServer", this);
+      break;
+    }
+  },
+
+  receiveMessage: function (message) {
+    // load devtools component on-demand
+    // Only reply if we are in a real content process
+    if (Services.appinfo.processType == Services.appinfo.PROCESS_TYPE_CONTENT) {
+      let {init} = Cu.import("resource://devtools/server/content-server.jsm", {});
+      init(message);
+    }
+  },
+};
+
+this.NSGetFactory = XPCOMUtils.generateNSGetFactory([ContentProcessSingleton]);