extensions/renderer/module_system.h

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef EXTENSIONS_RENDERER_MODULE_SYSTEM_H_
   6 #define EXTENSIONS_RENDERER_MODULE_SYSTEM_H_
   7
   8 #include <map>
   9 #include <set>
  10 #include <string>
  11 #include <vector>
  12
  13 #include "base/compiler_specific.h"
  14 #include "base/memory/linked_ptr.h"
  15 #include "base/memory/scoped_ptr.h"
  16 #include "extensions/renderer/native_handler.h"
  17 #include "extensions/renderer/object_backed_native_handler.h"
  18 #include "gin/modules/module_registry_observer.h"
  19 #include "v8/include/v8.h"
  20
  21 namespace extensions {
  22
  23 class ScriptContext;
  24
  25 // A module system for JS similar to node.js' require() function.
  26 // Each module has three variables in the global scope:
  27 //   - exports, an object returned to dependencies who require() this
  28 //     module.
  29 //   - require, a function that takes a module name as an argument and returns
  30 //     that module's exports object.
  31 //   - requireNative, a function that takes the name of a registered
  32 //     NativeHandler and returns an object that contains the functions the
  33 //     NativeHandler defines.
  34 //
  35 // Each module in a ModuleSystem is executed at most once and its exports
  36 // object cached.
  37 //
  38 // Note that a ModuleSystem must be used only in conjunction with a single
  39 // v8::Context.
  40 // TODO(koz): Rename this to JavaScriptModuleSystem.
  41 class ModuleSystem : public ObjectBackedNativeHandler,
  42                      public gin::ModuleRegistryObserver {
  43  public:
  44   class SourceMap {
  45    public:
  46     virtual ~SourceMap() {}
  47     virtual v8::Local<v8::Value> GetSource(v8::Isolate* isolate,
  48                                            const std::string& name) = 0;
  49     virtual bool Contains(const std::string& name) = 0;
  50   };
  51
  52   class ExceptionHandler {
  53    public:
  54     explicit ExceptionHandler(ScriptContext* context) : context_(context) {}
  55     virtual ~ExceptionHandler() {}
  56     virtual void HandleUncaughtException(const v8::TryCatch& try_catch) = 0;
  57
  58    protected:
  59     // Formats |try_catch| as a nice string.
  60     std::string CreateExceptionString(const v8::TryCatch& try_catch);
  61     // A script context associated with this handler. Owned by the module
  62     // system.
  63     ScriptContext* context_;
  64   };
  65
  66   // Enables native bindings for the duration of its lifetime.
  67   class NativesEnabledScope {
  68    public:
  69     explicit NativesEnabledScope(ModuleSystem* module_system);
  70     ~NativesEnabledScope();
  71
  72    private:
  73     ModuleSystem* module_system_;
  74     DISALLOW_COPY_AND_ASSIGN(NativesEnabledScope);
  75   };
  76
  77   // |source_map| is a weak pointer.
  78   ModuleSystem(ScriptContext* context, SourceMap* source_map);
  79   ~ModuleSystem() override;
  80
  81   // Require the specified module. This is the equivalent of calling
  82   // require('module_name') from the loaded JS files.
  83   v8::Local<v8::Value> Require(const std::string& module_name);
  84   void Require(const v8::FunctionCallbackInfo<v8::Value>& args);
  85
  86   // Run |code| in the current context with the name |name| used for stack
  87   // traces.
  88   v8::Local<v8::Value> RunString(v8::Local<v8::String> code,
  89                                  v8::Local<v8::String> name);
  90
  91   // Calls the specified method exported by the specified module. This is
  92   // equivalent to calling require('module_name').method_name() from JS.
  93   v8::Local<v8::Value> CallModuleMethod(const std::string& module_name,
  94                                         const std::string& method_name);
  95   v8::Local<v8::Value> CallModuleMethod(
  96       const std::string& module_name,
  97       const std::string& method_name,
  98       std::vector<v8::Local<v8::Value>>* args);
  99   v8::Local<v8::Value> CallModuleMethod(const std::string& module_name,
 100                                         const std::string& method_name,
 101                                         int argc,
 102                                         v8::Local<v8::Value> argv[]);
 103
 104   // Register |native_handler| as a potential target for requireNative(), so
 105   // calls to requireNative(|name|) from JS will return a new object created by
 106   // |native_handler|.
 107   void RegisterNativeHandler(const std::string& name,
 108                              scoped_ptr<NativeHandler> native_handler);
 109
 110   // Causes requireNative(|name|) to look for its module in |source_map_|
 111   // instead of using a registered native handler. This can be used in unit
 112   // tests to mock out native modules.
 113   void OverrideNativeHandlerForTest(const std::string& name);
 114
 115   // Executes |code| in the current context with |name| as the filename.
 116   void RunString(const std::string& code, const std::string& name);
 117
 118   // Make |object|.|field| lazily evaluate to the result of
 119   // require(|module_name|)[|module_field|].
 120   //
 121   // TODO(kalman): All targets for this method are ObjectBackedNativeHandlers,
 122   //               move this logic into those classes (in fact, the chrome
 123   //               object is the only client, only that needs to implement it).
 124   void SetLazyField(v8::Local<v8::Object> object,
 125                     const std::string& field,
 126                     const std::string& module_name,
 127                     const std::string& module_field);
 128
 129   void SetLazyField(v8::Local<v8::Object> object,
 130                     const std::string& field,
 131                     const std::string& module_name,
 132                     const std::string& module_field,
 133                     v8::AccessorNameGetterCallback getter);
 134
 135   // Make |object|.|field| lazily evaluate to the result of
 136   // requireNative(|module_name|)[|module_field|].
 137   // TODO(kalman): Same as above.
 138   void SetNativeLazyField(v8::Local<v8::Object> object,
 139                           const std::string& field,
 140                           const std::string& module_name,
 141                           const std::string& module_field);
 142
 143   // Passes exceptions to |handler| rather than console::Fatal.
 144   void SetExceptionHandlerForTest(scoped_ptr<ExceptionHandler> handler) {
 145     exception_handler_ = handler.Pass();
 146   }
 147
 148  protected:
 149   friend class ModuleSystemTestEnvironment;
 150   friend class ScriptContext;
 151   void Invalidate() override;
 152
 153  private:
 154   typedef std::map<std::string, linked_ptr<NativeHandler> > NativeHandlerMap;
 155
 156   // Retrieves the lazily defined field specified by |property|.
 157   static void LazyFieldGetter(v8::Local<v8::Name> property,
 158                               const v8::PropertyCallbackInfo<v8::Value>& info);
 159   // Retrieves the lazily defined field specified by |property| on a native
 160   // object.
 161   static void NativeLazyFieldGetter(
 162       v8::Local<v8::Name> property,
 163       const v8::PropertyCallbackInfo<v8::Value>& info);
 164
 165   // Called when an exception is thrown but not caught.
 166   void HandleException(const v8::TryCatch& try_catch);
 167
 168   void RequireForJs(const v8::FunctionCallbackInfo<v8::Value>& args);
 169   v8::Local<v8::Value> RequireForJsInner(v8::Local<v8::String> module_name);
 170
 171   typedef v8::Local<v8::Value>(ModuleSystem::*RequireFunction)(
 172       const std::string&);
 173   // Base implementation of a LazyFieldGetter which uses |require_fn| to require
 174   // modules.
 175   static void LazyFieldGetterInner(
 176       v8::Local<v8::String> property,
 177       const v8::PropertyCallbackInfo<v8::Value>& info,
 178       RequireFunction require_function);
 179
 180   // Return the named source file stored in the source map.
 181   // |args[0]| - the name of a source file in source_map_.
 182   v8::Local<v8::Value> GetSource(const std::string& module_name);
 183
 184   // Return an object that contains the native methods defined by the named
 185   // NativeHandler.
 186   // |args[0]| - the name of a native handler object.
 187   v8::Local<v8::Value> RequireNativeFromString(const std::string& native_name);
 188   void RequireNative(const v8::FunctionCallbackInfo<v8::Value>& args);
 189
 190   // Return a promise for a requested module.
 191   // |args[0]| - the name of a module.
 192   void RequireAsync(const v8::FunctionCallbackInfo<v8::Value>& args);
 193
 194   // Wraps |source| in a (function(define, require, requireNative, ...) {...}).
 195   v8::Local<v8::String> WrapSource(v8::Local<v8::String> source);
 196
 197   // NativeHandler implementation which returns the private area of an Object.
 198   void Private(const v8::FunctionCallbackInfo<v8::Value>& args);
 199
 200   // Loads and runs a Javascript module.
 201   v8::Local<v8::Value> LoadModule(const std::string& module_name);
 202
 203   // Invoked when a module is loaded in response to a requireAsync call.
 204   // Resolves |resolver| with |value|.
 205   void OnModuleLoaded(scoped_ptr<v8::Global<v8::Promise::Resolver>> resolver,
 206                       v8::Local<v8::Value> value);
 207
 208   // gin::ModuleRegistryObserver overrides.
 209   void OnDidAddPendingModule(
 210       const std::string& id,
 211       const std::vector<std::string>& dependencies) override;
 212
 213   // Marks any existing NativeHandler named |name| as clobbered.
 214   // See |clobbered_native_handlers_|.
 215   void ClobberExistingNativeHandler(const std::string& name);
 216
 217   ScriptContext* context_;
 218
 219   // A map from module names to the JS source for that module. GetSource()
 220   // performs a lookup on this map.
 221   SourceMap* source_map_;
 222
 223   // A map from native handler names to native handlers.
 224   NativeHandlerMap native_handler_map_;
 225
 226   // When 0, natives are disabled, otherwise indicates how many callers have
 227   // pinned natives as enabled.
 228   int natives_enabled_;
 229
 230   // Called when an exception is thrown but not caught in JS. Overridable by
 231   // tests.
 232   scoped_ptr<ExceptionHandler> exception_handler_;
 233
 234   // A set of native handlers that should actually be require()d as non-native
 235   // handlers. This is used for tests to mock out native handlers in JS.
 236   std::set<std::string> overridden_native_handlers_;
 237
 238   // A list of NativeHandlers that have been clobbered, either due to
 239   // registering a NativeHandler when one was already registered with the same
 240   // name, or due to OverrideNativeHandlerForTest. This is needed so that they
 241   // can be later Invalidated. It should only happen in tests.
 242   std::vector<linked_ptr<NativeHandler>> clobbered_native_handlers_;
 243
 244   base::WeakPtrFactory<ModuleSystem> weak_factory_;
 245
 246   DISALLOW_COPY_AND_ASSIGN(ModuleSystem);
 247 };
 248
 249 }  // namespace extensions
 250
 251 #endif  // EXTENSIONS_RENDERER_MODULE_SYSTEM_H_