chrome_frame/dll_redirector.h

   1 // Copyright (c) 2011 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 CHROME_FRAME_MODULE_UTILS_H_
   6 #define CHROME_FRAME_MODULE_UTILS_H_
   7
   8 #include <ObjBase.h>
   9 #include <windows.h>
  10
  11 #include "base/basictypes.h"
  12 #include "base/memory/scoped_ptr.h"
  13 #include "base/memory/singleton.h"
  14 #include "base/shared_memory.h"
  15
  16 // Forward
  17 namespace ATL {
  18 class CSecurityAttributes;
  19 }
  20 class Version;
  21
  22 // A singleton class that provides a facility to register the version of the
  23 // current module as the only version that should be loaded system-wide. If
  24 // this module is not the first instance loaded in the system, then the version
  25 // that loaded first will be delegated to. This makes a few assumptions:
  26 //  1) That different versions of the module this code is in reside in
  27 //     neighbouring versioned directories, e.g.
  28 //       C:\foo\bar\1.2.3.4\my_module.dll
  29 //       C:\foo\bar\1.2.3.5\my_module.dll
  30 //  2) That the instance of this class will outlive the module that may be
  31 //     delegated to. That is to say, that this class only guarantees that the
  32 //     module is loaded as long as this instance is active.
  33 //  3) The module this is compiled into is built with version info.
  34 class DllRedirector {
  35  public:
  36   // Returns the singleton instance.
  37   static DllRedirector* GetInstance();
  38
  39   virtual ~DllRedirector();
  40
  41   // Attempts to register this Chrome Frame version as the first loaded version
  42   // on the system. If this succeeds, return true. If it fails, it returns
  43   // false meaning that there is another version already loaded somewhere and
  44   // the caller should delegate to that version instead.
  45   bool DllRedirector::RegisterAsFirstCFModule();
  46
  47   // Unregisters the well known window class if we registered it earlier.
  48   // This is intended to be called from DllMain under PROCESS_DETACH.
  49   void DllRedirector::UnregisterAsFirstCFModule();
  50
  51   // Helper function to return the DllGetClassObject function pointer from
  52   // the given module. On success, the return value is non-null and module
  53   // will have had its reference count incremented.
  54   LPFNGETCLASSOBJECT GetDllGetClassObjectPtr();
  55
  56  protected:
  57   DllRedirector();
  58   friend struct DefaultSingletonTraits<DllRedirector>;
  59
  60   // Constructor used for tests.
  61   explicit DllRedirector(const char* shared_memory_name);
  62
  63   // Returns an HMODULE to the version of the module that should be loaded.
  64   virtual HMODULE GetFirstModule();
  65
  66   // Returns the version of the current module or NULL if none can be found.
  67   // The caller must free the Version.
  68   virtual Version* GetCurrentModuleVersion();
  69
  70   // Attempt to load the specified version dll. Finds it by walking up one
  71   // directory from our current module's location, then appending the newly
  72   // found version number. The Version class in base will have ensured that we
  73   // actually have a valid version and not e.g. ..\..\..\..\MyEvilFolder\.
  74   virtual HMODULE LoadVersionedModule(Version* version);
  75
  76   // Builds the necessary SECURITY_ATTRIBUTES to allow low integrity access
  77   // to an object. Returns true on success, false otherwise.
  78   virtual bool BuildSecurityAttributesForLock(
  79       ATL::CSecurityAttributes* sec_attr);
  80
  81   // Attempts to change the permissions on the given file mapping to read only.
  82   // Returns true on success, false otherwise.
  83   virtual bool SetFileMappingToReadOnly(base::SharedMemoryHandle mapping);
  84
  85   // Shared memory segment that contains the version beacon.
  86   scoped_ptr<base::SharedMemory> shared_memory_;
  87
  88   // The current version of the DLL to be loaded.
  89   scoped_ptr<Version> dll_version_;
  90
  91   // The handle to the first version of this module that was loaded. This
  92   // may refer to the current module, or another version of the same module
  93   // that we go and load.
  94   HMODULE first_module_handle_;
  95
  96   // Used for tests to override the name of the shared memory segment.
  97   std::string shared_memory_name_;
  98
  99   friend class ModuleUtilsTest;
 100
 101   DISALLOW_COPY_AND_ASSIGN(DllRedirector);
 102 };
 103
 104 #endif  // CHROME_FRAME_MODULE_UTILS_H_