Modifying detection of HTML page.

The method for retrieving the expected type description for HTML pages
was far more complex than it needed to be. We now use the
AssocQueryString API instead of trying to read the registry.

Author: jimevans

cpp/iedriver/DocumentHost.cpp

@@ -297,61 +297,31 @@ bool DocumentHost::IsHtmlPage(IHTMLDocument2* doc) {
     return false;
   }
 
-  std::wstring document_type_key_name= L"";
-  if (RegistryUtilities::GetRegistryValue(HKEY_CURRENT_USER,
-                                          L"Software\\Microsoft\\Windows\\Shell\\Associations\\UrlAssociations\\http\\UserChoice",
-                                          L"Progid",
-                                          &document_type_key_name)) {
-    // Look for the user-customization under Vista/Windows 7 first. If it's
-    // IE, set the document friendly name lookup key to 'htmlfile'. If not,
-    // set it to blank so that we can look up the proper HTML type.
-    if (document_type_key_name == L"IE.HTTP") {
-      document_type_key_name = L"htmlfile";
-    } else {
-      LOG(DEBUG) << "Unable to support custom document type: " << LOGWSTRING(document_type_key_name);
-      document_type_key_name = L"";
-    }
-  } else {
-    LOG(DEBUG) << "Unable to read document type from registry";
-  }
+  // Call once to get the required buffer size, then again to fill
+  // the buffer.
+  DWORD mime_type_name_buffer_size = 0;
+  HRESULT hr = ::AssocQueryString(0,
+                                  ASSOCSTR_FRIENDLYDOCNAME,
+                                  L".htm",
+                                  NULL,
+                                  NULL,
+                                  &mime_type_name_buffer_size);
+
+  std::vector<wchar_t> mime_type_name_buffer(mime_type_name_buffer_size);
+  hr = ::AssocQueryString(0,
+                          ASSOCSTR_FRIENDLYDOCNAME,
+                          L".htm",
+                          NULL,
+                          &mime_type_name_buffer[0],
+                          &mime_type_name_buffer_size);
 
-  if (document_type_key_name == L"") {
-    // To be technically correct, we should look up the extension specified
-    // for the text/html MIME type first (located in the "Extension" value
-    // of HKEY_CLASSES_ROOT\MIME\Database\Content Type\text/html), but that
-    // should always resolve to ".htm" anyway. From the extension, we can 
-    // find the browser-specific subkey of HKEY_CLASSES_ROOT, the default 
-    // value of which should contain the browser-specific friendly name of
-    // the MIME type for HTML documents, which is what 
-    // IHTMLDocument2::get_mimeType() returns.
-    if (!RegistryUtilities::GetRegistryValue(HKEY_CLASSES_ROOT,
-                                             L".htm",
-                                             L"",
-                                             &document_type_key_name)) {
-      LOG(WARN) << "Unable to read document type from registry for '.htm'";
-      return false;
-    }
-  }
-
-  // First try the (default) value for the subkey. Some browsers (Opera)
-  // do not write this information in the (default) value, so if that fails,
-  // try the FriendlyTypeName value.
-  std::wstring mime_type_name;
-  if (!RegistryUtilities::GetRegistryValue(HKEY_CLASSES_ROOT,
-                                           document_type_key_name,
-                                           L"",
-                                           &mime_type_name)) {
-    if (!RegistryUtilities::GetRegistryValue(HKEY_CLASSES_ROOT,
-                                             document_type_key_name,
-                                             L"FriendlyTypeName",
-                                             &mime_type_name)) {
-      LOG(WARN) << "Unable to read mime type from registry for document type";
-      return false;
-    }
+  if (FAILED(hr)) {
+    LOGHR(WARN, hr) << "Call to AssocQueryString failed in getting friendly name of .htm documents";
+    return false;
   }
 
+  std::wstring mime_type_name = &mime_type_name_buffer[0];
   std::wstring type_string = type;
-
   if (type_string == mime_type_name) {
     return true;
   }
@@ -364,7 +334,7 @@ bool DocumentHost::IsHtmlPage(IHTMLDocument2* doc) {
 
   if (L"Firefox HTML Document" == mime_type_name) {
     LOG(INFO) << "It looks like Firefox was once the default browser. " 
-        << "Guessing the page type from mime type alone";
+              << "Guessing the page type from mime type alone";
     return true;
   }