VirtualProtect platform abstraction.

src/xenia/base/memory.h

@@ -18,6 +18,21 @@
 #include "xenia/base/byte_order.h"
 
 namespace xe {
+namespace memory {
+
+// Returns the native page size of the system, in bytes.
+size_t page_size();
+
+enum class PageAccess {
+  kNoAccess = 0,
+  kReadOnly,
+  kReadWrite,
+};
+
+// Sets the access rights for the given block of memory and returns the previous
+// access rights. Both base_address and length will be adjusted to page_size().
+bool Protect(void* base_address, size_t length, PageAccess access,
+             PageAccess* out_old_access);
 
 inline size_t hash_combine(size_t seed) { return seed; }
 
@@ -28,6 +43,10 @@ size_t hash_combine(size_t seed, const T& v, const Ts&... vs) {
   return hash_combine(seed, vs...);
 }
 
+}  // namespace memory
+
+// TODO(benvanik): move into xe::memory::
+
 constexpr void* low_address(void* address) {
   return (void*)(uint64_t(address) & 0xFFFFFFFF);
 }

src/xenia/base/memory_win.cc

@@ -0,0 +1,73 @@
+/**
+ ******************************************************************************
+ * Xenia : Xbox 360 Emulator Research Project                                 *
+ ******************************************************************************
+ * Copyright 2015 Ben Vanik. All rights reserved.                             *
+ * Released under the BSD license - see LICENSE in the root for more details. *
+ ******************************************************************************
+ */
+
+#include "xenia/base/memory.h"
+
+#include "xenia/base/platform_win.h"
+
+namespace xe {
+namespace memory {
+
+size_t page_size() {
+  static size_t value = 0;
+  if (!value) {
+    SYSTEM_INFO si;
+    GetSystemInfo(&si);
+    value = si.dwAllocationGranularity;
+  }
+  return value;
+}
+
+bool Protect(void* base_address, size_t length, PageAccess access,
+             PageAccess* out_old_access) {
+  if (out_old_access) {
+    *out_old_access = PageAccess::kNoAccess;
+  }
+  DWORD new_protect;
+  switch (access) {
+    case PageAccess::kNoAccess:
+      new_protect = PAGE_NOACCESS;
+      break;
+    case PageAccess::kReadOnly:
+      new_protect = PAGE_READONLY;
+      break;
+    case PageAccess::kReadWrite:
+      new_protect = PAGE_READWRITE;
+      break;
+    default:
+      assert_unhandled_case(access);
+      break;
+  }
+  DWORD old_protect = 0;
+  BOOL result = VirtualProtect(base_address, length, new_protect, &old_protect);
+  if (result) {
+    if (out_old_access) {
+      switch (old_protect) {
+        case PAGE_NOACCESS:
+          *out_old_access = PageAccess::kNoAccess;
+          break;
+        case PAGE_READONLY:
+          *out_old_access = PageAccess::kReadOnly;
+          break;
+        case PAGE_READWRITE:
+          *out_old_access = PageAccess::kReadWrite;
+          break;
+        default:
+          assert_unhandled_case(access);
+          break;
+      }
+    }
+    return true;
+  } else {
+    return false;
+  }
+}
+
+}  // namespace memory
+}  // namespace xe

src/xenia/base/platform.h

@@ -76,9 +76,6 @@ const size_t max_path = 1024;  // PATH_MAX
 // Launches a web browser to the given URL.
 void LaunchBrowser(const char* url);
 
-// Returns the native page size of the system, in bytes.
-size_t page_size();
-
 }  // namespace xe
 
 #endif  // XENIA_BASE_PLATFORM_H_

src/xenia/base/platform_win.cc

@@ -11,16 +11,6 @@
 
 namespace xe {
 
-size_t page_size() {
-  static size_t value = 0;
-  if (!value) {
-    SYSTEM_INFO si;
-    GetSystemInfo(&si);
-    value = si.dwAllocationGranularity;
-  }
-  return value;
-}
-
 void LaunchBrowser(const char* url) {
   ShellExecuteA(NULL, "open", url, NULL, NULL, SW_SHOWNORMAL);
 }