lazily read/write context for all threads

GleeBug/Debugger.Loop.cpp

@@ -44,8 +44,6 @@ namespace GleeBug
                 {
                     mThread = mProcess->thread = &threadFound->second;
                     mRegisters = &mThread->registers;
-                    if (!mThread->RegReadContext())
-                        cbInternalError("ThreadInfo::RegReadContext() failed!");
                 }
                 else
                 {
@@ -64,6 +62,10 @@ namespace GleeBug
                 }
             }
 
+            //read register contexts
+            if(mProcess && !mProcess->RegReadContext())
+                cbInternalError("Process::RegReadContext() failed!");                        
+
             //call the pre debug event callback
             cbPreDebugEvent(mDebugEvent);
 
@@ -120,12 +122,9 @@ namespace GleeBug
                     mThread->registers.TrapFlag = false;
             }
 
-            //write the register context
+            //write register contexts
-            if (mThread)
+            if(mProcess && !mProcess->RegWriteContext())
-            {
+                cbInternalError("Process::RegWriteContext() failed!");
-                if (!mThread->RegWriteContext())
-                    cbInternalError("ThreadInfo::RegWriteContext() failed!");
-            }
 
             //continue the debug event
             if (!ContinueDebugEvent(mDebugEvent.dwProcessId, mDebugEvent.dwThreadId, mContinueStatus))

GleeBug/Debugger.Process.h

@@ -394,6 +394,24 @@ namespace GleeBug
             StepOver(std::bind(callback, debugger));
         }
 
+        bool RegReadContext()
+        {
+            auto result = true;
+            for(auto & thread : this->threads)
+                if(!thread.second.RegReadContext())
+                    result = false;
+            return result;
+        }
+
+        bool RegWriteContext()
+        {
+            auto result = true;
+            for(auto & thread : this->threads)
+                if(!thread.second.RegWriteContext())
+                    result = false;
+            return result;
+        }
+
         private:
             Capstone mCapstone;
     };

GleeBug/Debugger.Thread.Registers.GetSet.cpp

@@ -54,8 +54,10 @@
 
 namespace GleeBug
 {
-    ptr Registers::Get(R reg) const
+    ptr Registers::Get(R reg)
     {
+        handleLazyContext();
+
         switch (reg)
         {
         case R::DR0:
@@ -244,6 +246,8 @@ namespace GleeBug
 
     void Registers::Set(R reg, ptr value)
     {
+        handleLazyContext();
+
         switch (reg)
         {
         case R::DR0:
@@ -513,21 +517,27 @@ namespace GleeBug
         }
     }
 
-    bool Registers::GetFlag(F flag) const
+    bool Registers::GetFlag(F flag)
     {
+        handleLazyContext();
+
         return (mContext.EFlags & ptr(flag)) == ptr(flag);
     }
 
     void Registers::SetFlag(F flag, bool set)
     {
+        handleLazyContext();
+
         if (set)
             mContext.EFlags |= ptr(flag);
         else
             mContext.EFlags &= ~ptr(flag);
     }
 
-    void* Registers::getPtr(R reg) const
+    void* Registers::getPtr(R reg)
     {
+        handleLazyContext();
+
         switch (reg)
         {
         case R::DR0:

GleeBug/Debugger.Thread.Registers.cpp

@@ -102,13 +102,45 @@ namespace GleeBug
         memset(&this->mContext, 0, sizeof(CONTEXT));
     }
 
-    const CONTEXT* Registers::GetContext() const
+    const CONTEXT* Registers::GetContext()
     {
+        handleLazyContext();
         return &mContext;
     }
 
     void Registers::SetContext(const CONTEXT & context)
     {
+        handleLazyContext();
         this->mContext = context;
     }
+
+    void Registers::setContextLazy(CONTEXT* oldContext, HANDLE hThread)
+    {
+        this->mLazyOldContext = oldContext;
+        this->mLazyThread = hThread;
+        this->mLazySet = true;
+        this->mContext = *this->mLazyOldContext;        
+    }
+
+    bool Registers::handleLazyContext()
+    {
+        if(!this->mLazySet)
+            return true;
+
+        if(!this->mLazyOldContext || !this->mLazyThread) //assert
+            __debugbreak();
+
+        //TODO: handle failure of GetThreadContext
+        auto result = false;
+        if(GetThreadContext(this->mLazyThread, this->mLazyOldContext))
+        {
+            this->mContext = *this->mLazyOldContext;
+            result = true;
+        }
+        
+        this->mLazyOldContext = nullptr;
+        this->mLazyThread = nullptr;
+        this->mLazySet = false;        
+        return result;
+    }
 };

GleeBug/Debugger.Thread.Registers.h

@@ -11,6 +11,7 @@ namespace GleeBug
     class Registers
     {
         friend class Register;
+        friend class Thread;
 
     public:
         /**
@@ -123,7 +124,7 @@ namespace GleeBug
         \param reg The register to get.
         \return The register value.
         */
-        ptr Get(R reg) const;
+        ptr Get(R reg);
 
         /**
         \brief Sets a given register.
@@ -137,7 +138,7 @@ namespace GleeBug
         \param flag The flag to get.
         \return true if the flag is set, false otherwise.
         */
-        bool GetFlag(F flag) const;
+        bool GetFlag(F flag);
 
         /**
         \brief Sets a flag.
@@ -149,7 +150,7 @@ namespace GleeBug
         \brief Gets a pointer to the context object.
         \return This function will never return a nullptr.
         */
-        const CONTEXT* GetContext() const;
+        const CONTEXT* GetContext();
 
         /**
         \brief Sets the CONTEXT.
@@ -160,7 +161,24 @@ namespace GleeBug
     private:
         CONTEXT mContext;
 
-        void* getPtr(R reg) const;
+        CONTEXT* mLazyOldContext = nullptr;
+        HANDLE mLazyThread = nullptr;
+        bool mLazySet = false;
+
+        /**
+        \brief Lazily set CONTEXT. This will only actually retrieve the context if a function in this thread is called.
+        \param oldContext Pointer to the old context, used to determine if updates are required.
+        \param hThread Handle of the thread to get the context from if required.
+        */
+        void setContextLazy(CONTEXT* oldContext, HANDLE hThread);
+
+        /**
+        \brief Retrieve the actual context if setContextLazy has been called.
+        \return Whether retrieving the actual context was successful.
+        */
+        bool handleLazyContext();
+
+        void* getPtr(R reg);
     };
 };
 

GleeBug/Debugger.Thread.cpp

@@ -44,21 +44,17 @@ namespace GleeBug
     {
         memset(&this->mOldContext, 0, sizeof(CONTEXT));
         this->mOldContext.ContextFlags = CONTEXT_ALL; //TODO: granular control over what's required
-        if (GetThreadContext(this->hThread, &this->mOldContext))
+        this->registers.setContextLazy(&this->mOldContext, this->hThread);
-        {
-            this->registers.SetContext(this->mOldContext);
         return true;
     }
-        return false;
-    }
 
-    bool Thread::RegWriteContext() const
+    bool Thread::RegWriteContext()
     {
         //check if something actually changed
-        if (memcmp(&this->mOldContext, this->registers.GetContext(), sizeof(CONTEXT)) == 0)
+        if (memcmp(&this->mOldContext, &this->registers.mContext, sizeof(CONTEXT)) == 0)
             return true;
         //update the context
-        return !!SetThreadContext(this->hThread, this->registers.GetContext());
+        return !!SetThreadContext(this->hThread, &this->registers.mContext);
     }
 
     void Thread::StepInto()

GleeBug/Debugger.Thread.h

@@ -55,7 +55,7 @@ namespace GleeBug
         \brief Write the register context to the thread. This does nothing if the registers did not change.
         \return true if it succeeds, false if it fails.
         */
-        bool RegWriteContext() const;
+        bool RegWriteContext();
 
         /**
         \brief Step into.

TitanEngineEmulator/Emulator.h

@@ -235,6 +235,8 @@ public:
         auto thread = threadFromHandle(hActiveThread);
         if (!thread)
             return 0;
+        if(mIsRunning)
+            thread->RegReadContext();
         return thread->registers.Get(registerFromDword(IndexOfRegister));
     }
 
@@ -243,7 +245,11 @@ public:
         auto thread = threadFromHandle(hActiveThread);
         if (!thread)
             return false;
+        if(mIsRunning)
+            thread->RegReadContext();
         thread->registers.Set(registerFromDword(IndexOfRegister), NewRegisterValue);
+        if(mIsRunning)
+            thread->RegWriteContext();
         return true;
     }
 
@@ -252,6 +258,8 @@ public:
         auto thread = threadFromHandle(hActiveThread);
         if (!thread || !titcontext)
             return false;
+        if(mIsRunning)
+            thread->RegReadContext();
         memset(titcontext, 0, sizeof(TITAN_ENGINE_CONTEXT_t));
         auto context = thread->registers.GetContext();
         titcontext->cax = thread->registers.Gax();
@@ -294,6 +302,8 @@ public:
         auto thread = threadFromHandle(hActiveThread);
         if (!thread || !titcontext)
             return false;
+        if(mIsRunning)
+            thread->RegReadContext();
         thread->registers.Gax = titcontext->cax;
         thread->registers.Gcx = titcontext->ccx;
         thread->registers.Gdx = titcontext->cdx;
@@ -328,6 +338,8 @@ public:
         context.SegCs = titcontext->cs;
         context.SegSs = titcontext->ss;
         thread->registers.SetContext(context);
+        if(mIsRunning)
+            thread->RegWriteContext();
         return true;
     }
 
@@ -449,11 +461,17 @@ public:
     {
         if (!mProcess)
             return false;
-        return mProcess->SetHardwareBreakpoint(bpxAddress,
+        if(mIsRunning)
+            mProcess->RegReadContext();
+        if(!mProcess->SetHardwareBreakpoint(bpxAddress,
             (HardwareSlot)IndexOfRegister, [bpxCallBack](const BreakpointInfo & info)
         {
             (HWBPCALLBACK(bpxCallBack))((const void*)info.address);
-        }, hwtypeFromTitan(bpxType), hwsizeFromTitan(bpxSize));
+        }, hwtypeFromTitan(bpxType), hwsizeFromTitan(bpxSize)))
+            return false;
+        if(mIsRunning)
+            mProcess->RegWriteContext();
+        return true;
     }
 
     bool DeleteHardwareBreakPoint(DWORD IndexOfRegister)