Add UMA stats to record when DLLs are successfully blocked in the Browser.

chrome_elf/blacklist/blacklist.cc

Index: chrome_elf/blacklist/blacklist.cc
diff --git a/chrome_elf/blacklist/blacklist.cc b/chrome_elf/blacklist/blacklist.cc
index 958d7103b798ba5488b8d9857f7be6a06c20cecb..3310376f61df5a6226507e447301729d94b4942c 100644
--- a/chrome_elf/blacklist/blacklist.cc
+++ b/chrome_elf/blacklist/blacklist.cc
@@ -28,6 +28,9 @@ const wchar_t* g_troublesome_dlls[kTroublesomeDllsMaxCount] = {
   NULL,
 };
 
+bool g_blocked_dlls[kTroublesomeDllsMaxCount] = { false };
+int g_num_blocked_dlls = 0;
+
 const wchar_t kRegistryBeaconPath[] = L"SOFTWARE\\Google\\Chrome\\BLBeacon";
 const wchar_t kBeaconVersion[] = L"version";
 const wchar_t kBeaconState[] = L"state";
@@ -298,6 +301,7 @@ bool AddDllToBlacklist(const wchar_t* dll_name) {
   wcscpy(str_buffer, dll_name);
 
   g_troublesome_dlls[blacklist_size] = str_buffer;
+  g_blocked_dlls[blacklist_size] = false;
   return true;
 }
 
@@ -310,12 +314,43 @@ bool RemoveDllFromBlacklist(const wchar_t* dll_name) {
       delete[] g_troublesome_dlls[i];
       g_troublesome_dlls[i] = g_troublesome_dlls[blacklist_size - 1];
       g_troublesome_dlls[blacklist_size - 1] = NULL;
+
+      // Also update the stats recording if we have blocked this dll or not.
+      if (g_blocked_dlls[i])
+        --g_num_blocked_dlls;
+      g_blocked_dlls[i] = g_blocked_dlls[blacklist_size - 1];
       return true;
     }
   }
   return false;
 }
 
+// TODO(csharp): Maybe store these values in the registry so we can
+// still report them if Chrome crashes early.
+void SuccessfullyBlocked(const wchar_t** blocked_dlls, int* size) {

[robertshield, 2014/02/24 15:24:05]

null check the inputs

[csharp, 2014/02/24 21:37:16]

Done.

+  // If the array isn't big enough, just report the size it needs to be and
+  // return.
+  if (*size < g_num_blocked_dlls) {
+    *size = g_num_blocked_dlls;
+    return;
+  }
+
+  int strings_to_fill = 0;
+  for (int i = 0; strings_to_fill != g_num_blocked_dlls; ++i) {

[robertshield, 2014/02/24 15:24:05]

be paranoid: also bounds check the index |i| against the length of the list it
is indexing into.

[csharp, 2014/02/24 21:37:16]

Done.

+    if (g_blocked_dlls[i]) {
+      blocked_dlls[strings_to_fill] = g_troublesome_dlls[i];
+      ++strings_to_fill;
+    }
+  }
+}
+
+void BlockedDll(int blocked_index) {
+  if (!g_blocked_dlls[blocked_index]) {
+    ++g_num_blocked_dlls;
+    g_blocked_dlls[blocked_index] = true;
+  }
+}
+
 bool Initialize(bool force) {
   // Check to see that we found the functions we need in ntdll.
   if (!InitializeInterceptImports())