Cleanup browser blacklist code

chrome_elf/blacklist/blacklist.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome_elf/blacklist/blacklist.h"
 
 #include <string.h>
 
 #include "base/basictypes.h"
 #include "chrome_elf/blacklist/blacklist_interceptions.h"
 #include "sandbox/win/src/interception_internal.h"
 #include "sandbox/win/src/internal_types.h"
 #include "sandbox/win/src/sandbox_utils.h"
 #include "sandbox/win/src/service_resolver.h"
 #include "version.h"  // NOLINT
 
 // http://blogs.msdn.com/oldnewthing/archive/2004/10/25/247180.aspx
 extern "C" IMAGE_DOS_HEADER __ImageBase;
 
 namespace blacklist{
 
-const wchar_t* g_troublesome_dlls[kTroublesomeDllsMaxCount] = {};
-int g_troublesome_dlls_cur_index = 0;
+const wchar_t* g_troublesome_dlls[kTroublesomeDllsMaxCount] = {
+  // Keep this null pointer here to mark the end of the list.
+  NULL,
+};
 
 const wchar_t kRegistryBeaconPath[] = L"SOFTWARE\\Google\\Chrome\\BLBeacon";
 const wchar_t kBeaconVersion[] = L"version";
 const wchar_t kBeaconState[] = L"state";
 
 }  // namespace blacklist
 
 // Allocate storage for thunks in a page of this module to save on doing
 // an extra allocation at run time.
 #pragma section(".crthunk",read,execute)
@@ skipping 192 matching lines @@
                            kBeaconState,
                            0,
                            REG_DWORD,
                            reinterpret_cast<LPBYTE>(&blacklist_state),
                            sizeof(blacklist_state));
   ::RegCloseKey(key);
 
   return (result == ERROR_SUCCESS);
 }
 
+int BlacklistSize() {
+  int size = -1;
+  while(blacklist::g_troublesome_dlls[++size] != NULL);
+
+  return size;
+}
+
 bool AddDllToBlacklist(const wchar_t* dll_name) {
-  if (g_troublesome_dlls_cur_index >= kTroublesomeDllsMaxCount)
+  int blacklist_size = BlacklistSize();
+  // We need to leave one space at the end for the null pointer.
+  if (blacklist_size + 1 >= kTroublesomeDllsMaxCount)
     return false;
-  for (int i = 0; i < g_troublesome_dlls_cur_index; ++i) {
-    if (!wcscmp(g_troublesome_dlls[i], dll_name))
+  for (int i=0; i < blacklist_size; ++i) {
+    if (!_wcsicmp(g_troublesome_dlls[i], dll_name))
       return true;
   }
 
   // Copy string to blacklist.
   wchar_t* str_buffer = new wchar_t[wcslen(dll_name) + 1];
   wcscpy(str_buffer, dll_name);
 
-  g_troublesome_dlls[g_troublesome_dlls_cur_index] = str_buffer;
-  g_troublesome_dlls_cur_index++;
+  g_troublesome_dlls[blacklist_size] = str_buffer;
   return true;
 }
 
 bool RemoveDllFromBlacklist(const wchar_t* dll_name) {
-  for (int i = 0; i < g_troublesome_dlls_cur_index; ++i) {
-    if (!wcscmp(g_troublesome_dlls[i], dll_name)) {
+  int blacklist_size = BlacklistSize();
+  for (int i = 0; i < blacklist_size; ++i) {
+    if (!_wcsicmp(g_troublesome_dlls[i], dll_name)) {
       // Found the thing to remove. Delete it then replace it with the last
       // element.
-      g_troublesome_dlls_cur_index--;
       delete[] g_troublesome_dlls[i];
-      g_troublesome_dlls[i] = g_troublesome_dlls[g_troublesome_dlls_cur_index];
-      g_troublesome_dlls[g_troublesome_dlls_cur_index] = NULL;
+      g_troublesome_dlls[i] = g_troublesome_dlls[blacklist_size - 1];
+      g_troublesome_dlls[blacklist_size - 1] = NULL;
       return true;
     }
   }
   return false;
 }
 
 bool Initialize(bool force) {
 #if defined(_WIN64)
   // TODO(robertshield): Implement 64-bit support by providing 64-bit
   //                     interceptors.
@@ skipping 69 matching lines @@
   // Mark the thunk storage as executable and prevent any future writes to it.
   BOOL page_executable = VirtualProtect(&g_thunk_storage,
                                         sizeof(g_thunk_storage),
                                         PAGE_EXECUTE_READ,
                                         &old_protect);
 
   return NT_SUCCESS(ret) && page_executable;
 }
 
 }  // namespace blacklist