1 // Copyright (c) 2017 The Chromium Embedded Framework Authors. All rights 2 // reserved. Use of this source code is governed by a BSD-style license that 3 // can be found in the LICENSE file. 4 5 #ifndef CEF_LIBCEF_DLL_CTOCPP_CTOCPP_SCOPED_H_ 6 #define CEF_LIBCEF_DLL_CTOCPP_CTOCPP_SCOPED_H_ 7 #pragma once 8 9 #include "include/base/cef_logging.h" 10 #include "include/capi/cef_base_capi.h" 11 #include "include/cef_base.h" 12 #include "libcef_dll/wrapper_types.h" 13 14 // Wrap a C structure with a C++ class. This is used when the implementation 15 // exists on the other side of the DLL boundary but will have methods called on 16 // this side of the DLL boundary. 17 template <class ClassName, class BaseName, class StructName> 18 class CefCToCppScoped : public BaseName { 19 public: 20 CefCToCppScoped(const CefCToCppScoped&) = delete; 21 CefCToCppScoped& operator=(const CefCToCppScoped&) = delete; 22 23 // Create a new wrapper instance for a structure reference received from the 24 // other side. The caller owns the CToCpp wrapper instance but not necessarily 25 // the underling object on the CppToC side (depends if s->del is non-NULL). 26 // The returned wrapper object can be used as either a scoped argument or to 27 // pass ownership. For example: 28 // 29 // void my_method(my_type1_t* struct1, my_type2_t* struct2) { 30 // // Passes ownership to MyMethod1(). 31 // MyMethod1(MyType1CToCpp::Wrap(struct1)); 32 // 33 // // Passes reference to MyMethod2(). 34 // CefOwnPtr<MyType1> obj2 = MyType2CToCpp::Wrap(struct2); 35 // MyMethod2(obj2.get()); 36 // // |obj2| is deleted when my_method() goes out of scope. 37 // } 38 // 39 // void MyMethod1(CefOwnPtr<MyType1> obj1) { 40 // // |obj1| is deleted when MyMethod1() goes out of scope. 41 // } 42 // 43 // void MyMethod2(CefRawPtr<MyType2> obj2) { 44 // } 45 static CefOwnPtr<BaseName> Wrap(StructName* s); 46 47 // Retrieve the underlying structure reference from a wrapper instance for 48 // return back to the other side. Ownership will be passed back to the other 49 // side and the wrapper will be deleted. For example: 50 // 51 // void MyMethod(CefOwnPtr<MyType> obj) { 52 // // Ownership of the underlying MyType object is passed to my_method(). 53 // my_method(MyTypeCToCpp::UnwrapOwn(std::move(obj))); 54 // // |obj| is now NULL. 55 // } 56 static StructName* UnwrapOwn(CefOwnPtr<BaseName> c); 57 58 // Retrieve the underlying structure reference from a wrapper instance for 59 // return back to the other side. Ownership does not change. For example: 60 // 61 // void MyMethod(CefRawPtr<MyType> obj) { 62 // // A reference is passed to my_method(). Ownership does not change. 63 // my_method2(MyTypeCToCpp::UnwrapRaw(obj)); 64 // } 65 static StructName* UnwrapRaw(CefRawPtr<BaseName> c); 66 67 // Override delete operator to properly delete the WrapperStruct. 68 // ~CefCToCppScoped will be called first followed by this method. 69 static void operator delete(void* ptr); 70 71 protected: 72 CefCToCppScoped() = default; 73 virtual ~CefCToCppScoped() = default; 74 75 // If returning the structure across the DLL boundary use Unwrap() instead. GetStruct()76 StructName* GetStruct() const { 77 WrapperStruct* wrapperStruct = GetWrapperStruct(this); 78 // Verify that the wrapper offset was calculated correctly. 79 DCHECK_EQ(kWrapperType, wrapperStruct->type_); 80 return wrapperStruct->struct_; 81 } 82 83 private: 84 // Used to associate this wrapper object and the structure reference received 85 // from the other side. 86 struct WrapperStruct; 87 88 static WrapperStruct* GetWrapperStruct(const BaseName* obj); 89 90 // Unwrap as the derived type. 91 static StructName* UnwrapDerivedOwn(CefWrapperType type, 92 CefOwnPtr<BaseName> c); 93 static StructName* UnwrapDerivedRaw(CefWrapperType type, 94 CefRawPtr<BaseName> c); 95 96 static CefWrapperType kWrapperType; 97 }; 98 99 template <class ClassName, class BaseName, class StructName> 100 struct CefCToCppScoped<ClassName, BaseName, StructName>::WrapperStruct { 101 CefWrapperType type_; 102 StructName* struct_; 103 ClassName wrapper_; 104 }; 105 106 template <class ClassName, class BaseName, class StructName> 107 CefOwnPtr<BaseName> CefCToCppScoped<ClassName, BaseName, StructName>::Wrap( 108 StructName* s) { 109 if (!s) 110 return CefOwnPtr<BaseName>(); 111 112 // Wrap their structure with the CefCToCpp object. 113 WrapperStruct* wrapperStruct = new WrapperStruct; 114 wrapperStruct->type_ = kWrapperType; 115 wrapperStruct->struct_ = s; 116 117 return CefOwnPtr<BaseName>(&wrapperStruct->wrapper_); 118 } 119 120 template <class ClassName, class BaseName, class StructName> 121 StructName* CefCToCppScoped<ClassName, BaseName, StructName>::UnwrapOwn( 122 CefOwnPtr<BaseName> c) { 123 if (!c.get()) 124 return nullptr; 125 126 WrapperStruct* wrapperStruct = GetWrapperStruct(c.get()); 127 128 // If the type does not match this object then we need to unwrap as the 129 // derived type. 130 if (wrapperStruct->type_ != kWrapperType) 131 return UnwrapDerivedOwn(wrapperStruct->type_, std::move(c)); 132 133 StructName* orig_struct = wrapperStruct->struct_; 134 135 #if DCHECK_IS_ON() 136 // We should own the object currently. 137 cef_base_scoped_t* base = reinterpret_cast<cef_base_scoped_t*>(orig_struct); 138 DCHECK(base && base->del); 139 #endif 140 141 // Don't delete the original object when the wrapper is deleted. 142 wrapperStruct->struct_ = nullptr; 143 144 // Return the original structure. 145 return orig_struct; 146 // The wrapper |c| is deleted when this method goes out of scope. 147 } 148 149 template <class ClassName, class BaseName, class StructName> 150 StructName* CefCToCppScoped<ClassName, BaseName, StructName>::UnwrapRaw( 151 CefRawPtr<BaseName> c) { 152 if (!c) 153 return nullptr; 154 155 WrapperStruct* wrapperStruct = GetWrapperStruct(c); 156 157 // If the type does not match this object then we need to unwrap as the 158 // derived type. 159 if (wrapperStruct->type_ != kWrapperType) 160 return UnwrapDerivedRaw(wrapperStruct->type_, c); 161 162 // Return the original structure. 163 return wrapperStruct->struct_; 164 } 165 166 template <class ClassName, class BaseName, class StructName> 167 NO_SANITIZE("cfi-icall") 168 void CefCToCppScoped<ClassName, BaseName, StructName>::operator delete( 169 void* ptr) { 170 WrapperStruct* wrapperStruct = GetWrapperStruct(static_cast<BaseName*>(ptr)); 171 // Verify that the wrapper offset was calculated correctly. 172 DCHECK_EQ(kWrapperType, wrapperStruct->type_); 173 174 // May be NULL if UnwrapOwn() was called. 175 cef_base_scoped_t* base = 176 reinterpret_cast<cef_base_scoped_t*>(wrapperStruct->struct_); 177 178 // If we own the object (base->del != NULL) then notify the other side that 179 // the object has been deleted. 180 if (base && base->del) 181 base->del(base); 182 183 // Delete the wrapper structure without executing ~CefCToCppScoped() an 184 // additional time. 185 ::operator delete(wrapperStruct); 186 } 187 188 template <class ClassName, class BaseName, class StructName> 189 typename CefCToCppScoped<ClassName, BaseName, StructName>::WrapperStruct* 190 CefCToCppScoped<ClassName, BaseName, StructName>::GetWrapperStruct( 191 const BaseName* obj) { 192 // Offset using the WrapperStruct size instead of individual member sizes to 193 // avoid problems due to platform/compiler differences in structure padding. 194 return reinterpret_cast<WrapperStruct*>( 195 reinterpret_cast<char*>(const_cast<BaseName*>(obj)) - 196 (sizeof(WrapperStruct) - sizeof(ClassName))); 197 } 198 199 #endif // CEF_LIBCEF_DLL_CTOCPP_CTOCPP_SCOPED_H_ 200