Final Fixes. Now I suppose everything works correctly. Test by yourself.

GleeBug/Debugger.Loop.Exception.cpp

@@ -256,28 +256,63 @@ namespace GleeBug
             return;
         }
 
-
+        //TODO: If I only have a page with Read bp and the exception was not on read, I don't execute the callback. Because since this was implemented with PAGE_GUARD, writtes or executes still trigger
-        /*
+        //This callback.
-        Access = 1,
+        //FIX: If the memoryBreakpointPages for this page does not have a access flag and has a read flag, but the exception was not on read. Then we resume the debuggee.
-        Read = 2,
+        if ((exceptionRecord.ExceptionInformation[0] != 0))
-        Write = 4,
-        Execute = 8
-        */
-        //The generated exception on this page was on Read. It should be expected that the breakpoint is also on Read. Or on Access.
-        //Yes - I know that the software itself may have been 0x1337 enough and purposely generated an exception convincing me that it is my bpx >_>.
-        //We shouldn't care about other stuff such as Write or Execute since these breakpoints are implemented with Access Violation.
-        if (!(pageProperties.Type & 0x1))
         {
-            if ((exceptionRecord.ExceptionInformation[0] == 0) && (!(pageProperties.Type & 0x2)))
+            //The bpx is solely on read.
+            if (((pageProperties.Type & 0x2) != 0) && ((pageProperties.Type & 0x1) == 0))
+               {
+                   mContinueStatus = DBG_CONTINUE;
+                    //We restore the protection
+                    if (!mProcess->MemProtect(pageAddr, PAGE_SIZE, pageProperties.OldProtect))
+                    {
+                        sprintf_s(error, "MemProtect failed on 0x%p", pageAddr);
+                        cbInternalError(error);
+                    }
+
+                    mThread->StepInternal(std::bind([this, pageAddr]()
+                    {
+                        //seek out the page address
+                        auto found_page = mProcess->memoryBreakpointPages.find(pageAddr);
+                        if (found_page == mProcess->memoryBreakpointPages.end())
+                        {
+                            //no page being used by bpx? Then just return
+                            return;
+                        }
+                        mProcess->MemProtect(pageAddr, PAGE_SIZE, found_page->second.NewProtect);
+                        return;
+                    }));
+                    return;
+                }
+            else if (((pageProperties.Type & 0x1) != 0))
+            {
+                //We are fine if the breakpoint is on Access and somethine other than a read occurred.
+            }
+            else
+            {
+                //This exception handler was called within a page that had no breakpoints on read or access. Probably the program generated this exception! what a 0x1337 brat.
+                //In this situation we return control to debuggee.
+                return;
+            }
+
+        }
+        else
+        {
+            //The generated exception is on read.
+            //If the page doesn't have a breakpoint on read or on access then something else must have gone wrong - we pass execution to debuggee.
+            if ((!(pageProperties.Type & 0x2)) && (!(pageProperties.Type & 0x1)))
             {
-                //perhaps the program generated such exception
                 return;
             }
         }
+        
 
         /*
         ASSUME:
         The breakpoint at exceptionAddress was indeed generated by me.
+        Its safe to call the callbacks.
         */
         //generic breakpoint callback function.
         cbBreakpoint(info);
@@ -333,8 +368,10 @@ namespace GleeBug
 
     void Debugger::exceptionAccessViolation(const EXCEPTION_RECORD & exceptionRecord, bool firstChance)
     {
-        //Same shit as before
+        /*
-
+        ASSUME:
+        exceptionAddress may or may not have been generated by your breakpoints.
+        */
         char error[128] = "";
         auto exceptionAddress = ptr(exceptionRecord.ExceptionInformation[1]);
 
@@ -342,32 +379,49 @@ namespace GleeBug
         auto foundRange = mProcess->memoryBreakpointRanges.find(Range(exceptionAddress, exceptionAddress));
         if (foundRange == mProcess->memoryBreakpointRanges.end())
         {
-            //if not in range, check if a memory breakpoint is in the accessed page
+            //if not in range, check if a memory breakpoint is in the accessed page 
             auto foundPage = mProcess->memoryBreakpointPages.find(exceptionAddress & ~(PAGE_SIZE - 1));
             if (foundPage != mProcess->memoryBreakpointPages.end())
             {
+                //(this means that by our fault the program generated an exception, we should clean it)
                 mContinueStatus = DBG_CONTINUE;
                 //if the page contains a memory breakpoint we have to restore the old protection to correctly resume the debuggee
                 const auto & page = foundPage->second;
                 const auto pBaseAddr = foundPage->first;
-                //TODO: single step and page protection changes
+
-                //FIXED
+                //We restore the protection
                 if (!mProcess->MemProtect(foundPage->first, PAGE_SIZE, foundPage->second.OldProtect))
                 {
                     sprintf_s(error, "MemProtect failed on 0x%p", foundPage->first);
                     cbInternalError(error);
                 }
-                //step + restore new protection to keep bp 
+
-                mThread->StepInternal(std::bind([this, page, pBaseAddr]()
+                //However the following situations may occur:
+                // The instruction we singlestep to is a software breakpoint, which may execute a callback, that can :
+                // -actually delete a memory breakpoint that takes this page into account 
+                // -add more memory breakpoints
+                //The solution: We just try to see if the page is mapped into memoryBreakpointPages. If the page is in deed being used by any memory breakpoint,
+                // then we ought to restore the protection.
+                mThread->StepInternal(std::bind([this, pBaseAddr]()
                 {
-                    mProcess->MemProtect(pBaseAddr, PAGE_SIZE, page.NewProtect);
+                    //seek out the page address
+                    auto found_page = mProcess->memoryBreakpointPages.find(pBaseAddr);
+                    if (found_page == mProcess->memoryBreakpointPages.end())
+                    {
+                        //no page being used by bpx? Then just return
+                        return;
+                    }
+                    mProcess->MemProtect(pBaseAddr, PAGE_SIZE, found_page->second.NewProtect);
                     return;
                 }));
             }
             return;
         }
 
-        //find the breakpoint associated with the hit breakpoint range
+        /*
+        ASSUME:
+        exceptionAddress is indeed inside a breakpoint range you have defined.
+        */
         auto foundInfo = mProcess->breakpoints.find({ BreakpointType::Memory, foundRange->first });
         if (foundInfo == mProcess->breakpoints.end())
         {
@@ -386,39 +440,48 @@ namespace GleeBug
         printf("memory breakpoint: 0x%p (size: %d)\n", info.address, info.internal.memory.size);
 
         //TODO: check if the right type is accessed (ExceptionInformation[0])
-        //FIXED: Marques
+        //FIXED: 
         auto bpxPage = mProcess->memoryBreakpointPages.find(exceptionAddress & ~(PAGE_SIZE - 1));
+        auto pageAddr = bpxPage->first;
+        auto pageProperties = bpxPage->second;
+
         if (bpxPage == mProcess->memoryBreakpointPages.end())
         {
             sprintf_s(error, "Process::memoryBreakPointPages data structure is incosistent, should dump page at 0x%p", exceptionAddress & ~(PAGE_SIZE - 1));
             cbInternalError(error);
             return;
         }
+
+
+        
         /*
         Access = 1,
         Read = 2,
         Write = 4,
         Execute = 8
         */
-        //Write but the bpx was not on write
+        //ExceptionInformation[0] should be considered as 1 or 8, because these are for exceptions generated on write or execute.
-        //We shouldn't care about other stuff such as read or access because those were implemented with page guards.
+        //Execute is only implemented with page guard if no Data-Execution-Prevention is implemented by the Kernel.
-        if ((exceptionRecord.ExceptionInformation[0] == 1) && (!(bpxPage->second.Type & 0x4)))
+        if ((exceptionRecord.ExceptionInformation[0] == 1) && (!(pageProperties.Type & 4)))
         {
-            //perhaps the program generated such exception
+            //The exception was on Write but there was no page breakpoint in Write? Then the program changed the page permissions, or naturally overwritten protected data. We do not interfere.
             return;
         }
 
-        //Exec but bpx was not on exec.
+        if ((exceptionRecord.ExceptionInformation[0] == 8) && (!(pageProperties.Type & 8)))
-        if ((exceptionRecord.ExceptionInformation[0] == 8) && (!(bpxPage->second.Type & 0x8)))
         {
-            //perhaps the program generated such exception
+            //The exception was on Execution but there was no page breakpoint in Execute? Then the program changed the page permissions, or naturally executed protected code. We do not interfere.
             return;
         }
+        /*
+        ASSUME:
+        The breakpoint at exceptionAddress was indeed generated by me.
+        */
         //generic breakpoint callback function.
         cbBreakpoint(info);
 
         //TODO: execute the user callback (if present)
-        //FIXED: Marques
+        //FIXED:
         auto bpxCb = mProcess->breakpointCallbacks.find({ BreakpointType::Memory, info.address });
         if (bpxCb != mProcess->breakpointCallbacks.end())
         {
@@ -429,26 +492,36 @@ namespace GleeBug
         mContinueStatus = DBG_CONTINUE;
         //TODO: single step and restore page protection
         //FIXED:
-        if (!mProcess->MemProtect(bpxPage->first, PAGE_SIZE, bpxPage->second.OldProtect))
+        if (!mProcess->MemProtect(pageAddr, PAGE_SIZE, pageProperties.OldProtect))
         {
-            sprintf_s(error, "MemProtect failed on 0x%p", bpxPage->first);
+            sprintf_s(error, "MemProtect failed on 0x%p", pageAddr);
             cbInternalError(error);
         }
         //Pass info as well
-        auto pageAddr = bpxPage->first;
+        mThread->StepInternal(std::bind([this, pageAddr]()
-        auto pageProperties = bpxPage->second;
-        mThread->StepInternal(std::bind([this, info, pageAddr, pageProperties]()
         {
-            //Check if the bpx still exists
+            //With page check this should work better: So when we reach this part of the code we are sure that:
-            auto found_range = mProcess->memoryBreakpointRanges.find(Range(info.address, info.address));
+            //-The exception Address In deed corresponded to an existing (now possibly deleted) memory breakpoint range
-            if (found_range != mProcess->memoryBreakpointRanges.end())
+            //-memoryBreakpointPages was in deed consistent with this memory address that generated the exception (The data structure wasn't corrupted somehow)
+            //So our new technique basically checks if the page address is still inside memoryBreakpointRanges structure. If this is true, we simply apply the NewProtect.
+            //Wide variety of possible scenarios:
+            //-Bpx on this page and bpx is not singleshot: In the case of PAGE_GUARD page protection (handled by this exception handler), if the page permission map persists, we simply 
+            // enforce the newProtect because this page belongs to a breakpoint somewhere.
+            //-Bpx is singleshot: Then it was deleted by the end of this call. If the refcount is zero, then we dont find the page on the Memory map, so assume no more memory breakpoints happen there.
+            // therefore, we do not enforce new protection.
+            //-Bpx was deleted on the handler: Again the page may or may not be mapped on memoryBreakpointPages. If the bp was deleted, and there are no more breakpoints in this page - The page does not exist on the map and therefore we do not restore old page protection.
+            //-Bpx was deleted on the handler AND a new breakpoint was added: if the bpx was deleted, and a new one was added on this page then, surely the page is mapped under memoryBreakpointPages.
+            //Check if the memory page is mapped
+
+            auto found_page = mProcess->memoryBreakpointPages.find(pageAddr);
+            if (found_page != mProcess->memoryBreakpointPages.end())
             {
-                mProcess->MemProtect(pageAddr, PAGE_SIZE, pageProperties.NewProtect);
+                mProcess->MemProtect(pageAddr, PAGE_SIZE, found_page->second.NewProtect);
             }
             return;
         }));
 
-        if (foundInfo->second.singleshoot)
+        if (info.singleshoot)
         {
             mProcess->DeleteMemoryBreakpoint(exceptionAddress);
         }

MyDebugger/MyDebugger.h

@@ -19,6 +19,7 @@ protected:
         unsigned char dataToExec[4];
         const char tmp[] = "aaaa";
 
+
         printf("Reached memory breakpoint! GIP: 0x%p\n",
             mRegisters->Gip());
 
@@ -30,6 +31,13 @@ protected:
         }
 
         mProcess->DeleteMemoryBreakpoint(mRegisters->Gip());
+        memcpy(dataToExec, tmp, 4);
+        mProcess->MemReadUnsafe(mRegisters->Gip(), dataToExec, 4);
+        printf("\n What are my bytes? I am so lost.. Dump: ");
+        for (int i = 0; i < 4; i++)
+        {
+            printf("%02X ", dataToExec[i]);
+        }
         mProcess->SetMemoryBreakpoint(mRegisters->Gip() + 1, 0x1, this, &MyDebugger::cbMemoryBreakpoint2, MemoryType::Access, false);
         memcpy(dataToExec, tmp, 4);
         mProcess->MemReadUnsafe(mRegisters->Gip(), dataToExec, 4);
@@ -50,7 +58,7 @@ protected:
         auto addr = mRegisters->Esi();
 #endif //_WIN64
         printf("Addr: 0x%p\n", addr);
-        if (mProcess->SetMemoryBreakpoint(addr, 0x1, this, &MyDebugger::cbMemoryBreakpoint, MemoryType::Access, false))
+        if (mProcess->SetMemoryBreakpoint(addr, 0x10000, this, &MyDebugger::cbMemoryBreakpoint, MemoryType::Execute, false))
             puts("Memory breakpoint set!");
         else
             puts("Failed to set memory breakpoint...");