Add basic infrastructure for protecting V8's heap when leaving the VM...

src/platform-win32.cc

 // Copyright 2006-2008 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 783 matching lines @@
     SYSTEM_INFO info;
     GetSystemInfo(&info);
     allocate_alignment = info.dwAllocationGranularity;
   }
   return allocate_alignment;
 }
 
 
 void* OS::Allocate(const size_t requested,
                    size_t* allocated,
-                   bool executable) {
+                   bool is_executable) {
   // VirtualAlloc rounds allocated size to page size automatically.
   size_t msize = RoundUp(requested, GetPageSize());
 
   // Windows XP SP2 allows Data Excution Prevention (DEP).
-  int prot = executable ? PAGE_EXECUTE_READWRITE : PAGE_READWRITE;
+  int prot = is_executable ? PAGE_EXECUTE_READWRITE : PAGE_READWRITE;
   LPVOID mbase = VirtualAlloc(NULL, msize, MEM_COMMIT | MEM_RESERVE, prot);
   if (mbase == NULL) {
     LOG(StringEvent("OS::Allocate", "VirtualAlloc failed"));
     return NULL;
   }
 
   ASSERT(IsAligned(reinterpret_cast<size_t>(mbase), OS::AllocateAlignment()));
 
   *allocated = msize;
   UpdateAllocatedSpaceLimits(mbase, msize);
   return mbase;
 }
 
 
-void OS::Free(void* buf, const size_t length) {
+void OS::Free(void* address, const size_t size) {
   // TODO(1240712): VirtualFree has a return value which is ignored here.
-  VirtualFree(buf, 0, MEM_RELEASE);
-  USE(length);
+  VirtualFree(address, 0, MEM_RELEASE);
+  USE(size);
 }
 
 
+#ifdef ENABLE_HEAP_PROTECTION
+
+void OS::Protect(void* address, size_t size) {
+  // TODO(1240712): VirtualProtect has a return value which is ignored here.
+  DWORD old_protect;
+  VirtualProtect(address, size, PAGE_READONLY, &old_protect);
+}
+
+
+void OS::Unprotect(void* address, size_t size, bool is_executable) {
+  // TODO(1240712): VirtualProtect has a return value which is ignored here.
+  DWORD new_protect = is_executable ? PAGE_EXECUTE_READWRITE : PAGE_READWRITE;
+  DWORD old_protect;
+  VirtualProtect(address, size, new_protect, &old_protect);
+}
+
+#endif
+
+
 void OS::Sleep(int milliseconds) {
   ::Sleep(milliseconds);
 }
 
 
 void OS::Abort() {
   if (!IsDebuggerPresent()) {
 #ifdef _MSC_VER
     // Make the MSVCRT do a silent abort.
     _set_abort_behavior(0, _WRITE_ABORT_MSG);
@@ skipping 451 matching lines @@
 }
 
 
 VirtualMemory::~VirtualMemory() {
   if (IsReserved()) {
     if (0 == VirtualFree(address(), 0, MEM_RELEASE)) address_ = NULL;
   }
 }
 
 
-bool VirtualMemory::Commit(void* address, size_t size, bool executable) {
-  int prot = executable ? PAGE_EXECUTE_READWRITE : PAGE_READWRITE;
+bool VirtualMemory::Commit(void* address, size_t size, bool is_executable) {
+  int prot = is_executable ? PAGE_EXECUTE_READWRITE : PAGE_READWRITE;
   if (NULL == VirtualAlloc(address, size, MEM_COMMIT, prot)) {
     return false;
   }
 
   UpdateAllocatedSpaceLimits(address, size);
   return true;
 }
 
 
 bool VirtualMemory::Uncommit(void* address, size_t size) {
@@ skipping 515 matching lines @@
 
   // Release the thread handles
   CloseHandle(data_->sampler_thread_);
   CloseHandle(data_->profiled_thread_);
 }
 
 
 #endif  // ENABLE_LOGGING_AND_PROFILING
 
 } }  // namespace v8::internal