Run a single FilterEngine instance in a separate process

AdblockPlusEngine/main.cpp

 #include <AdblockPlus.h>
 #include <iostream>
+#include <Lmcons.h>
 #include <ShlObj.h>
 #include <sstream>
 #include <vector>
 #include <Windows.h>
 #include <Sddl.h>
 
 namespace
 {
-  const std::wstring pipeName = L"\\\\.\\pipe\\adblockplusengine";

[Wladimir Palant, 2013/05/23 14:25:01]

I realized that the pipe name should be user-specific - if a different user runs
Adblock Plus on the same machine, this user should have a different pipe. Please
use GetUserName() and incorporate it into the pipe name.

[Felix Dahlke, 2013/05/23 19:10:44]

Oh, you're right. Appended the user name. Considered using the SID instead, but
it's a hassle to get and I don't think using the name will cause problems here.

[Wladimir Palant, 2013/05/23 20:10:15]

Not sure whether the user name can be changed but definitely not when the user
is logged in - so not an issue.

+  std::wstring GetUserName()
+  {
+    const DWORD maxLength = UNLEN + 1;
+    std::auto_ptr<wchar_t> buffer(new wchar_t[maxLength]);
+    DWORD length = maxLength;
+    if (!::GetUserName(buffer.get(), &length))
+    {
+      std::stringstream stream;
+      stream << "Failed to get the current user's name (Error code: " << GetLastError() << ")";
+      throw std::runtime_error("Failed to get the current user's name");
+    }
+    return std::wstring(buffer.get(), length);
+  }
+
+  const std::wstring pipeName = L"\\\\.\\pipe\\adblockplusengine_" + GetUserName();
   const int bufferSize = 1024;
   std::auto_ptr<AdblockPlus::FilterEngine> filterEngine;
 
   class AutoHandle
   {
   public:
     AutoHandle()
     {
     }
 
@@ skipping 48 matching lines @@
   std::vector<std::string> UnmarshalStrings(const std::string& message)
   {
     std::stringstream stream(message);
     std::vector<std::string> strings;
     std::string string;
     while (std::getline(stream, string, ';'))
         strings.push_back(string);
     return strings;
   }
 
-  std::string ToString(std::wstring value)
-  {
-    int size = WideCharToMultiByte(CP_UTF8, 0, value.c_str(), value.length(), 0, 0, 0, 0);

[Wladimir Palant, 2013/05/23 14:25:01]

Error case (size is 0 for a value with non-zero length) still isn't handled
here.

[Felix Dahlke, 2013/05/23 19:10:44]

It is, it returns an empty string. I thought it was better not to crash hard if
some conversion fails. The code I copied from libadblockplus handles the return
value of the first call, but not for the second, not exactly sure why.

[Wladimir Palant, 2013/05/23 20:10:15]

We should actually crash early here. While I cannot imagine what can cause a
conversion to UTF8 to fail, I am certain that I don't want to program to try
continue working after it - it might cause unexplainable issues further on.

The second return value is ignored because WideCharToMultiByte supposedly
checked the string on first call - it shouldn't detect any new issues on next
round.

-    std::auto_ptr<char> converted(new char[size]);
-    WideCharToMultiByte(CP_UTF8, 0, value.c_str(), value.length(), converted.get(), size, 0, 0);
-    std::string string(converted.get(), size);
-    return string;
+  std::string ToUtf8String(std::wstring str)
+  {
+    size_t length = str.size();
+    if (length == 0)
+      return std::string();
+
+    DWORD utf8StringLength = WideCharToMultiByte(CP_UTF8, 0, str.c_str(), length, 0, 0, 0, 0);
+    if (utf8StringLength == 0)
+      throw std::runtime_error("Failed to determine the required buffer size");
+
+    std::string utf8String(utf8StringLength, '\0');
+    WideCharToMultiByte(CP_UTF8, 0, str.c_str(), length, &utf8String[0], utf8StringLength, 0, 0);
+    return utf8String;
   }
 
   std::string ReadMessage(HANDLE pipe)
   {
     std::stringstream stream;
     std::auto_ptr<char> buffer(new char[bufferSize]);
     bool doneReading = false;
     while (!doneReading)
     {
       DWORD bytesRead;
@@ skipping 71 matching lines @@
     appDataPath.assign(pathBuffer);
     CoTaskMemFree(pathBuffer);
   }
   else
   { 
     std::auto_ptr<wchar_t> pathBuffer(new wchar_t[MAX_PATH]); 
     if (!SHGetSpecialFolderPath(0, pathBuffer.get(), CSIDL_LOCAL_APPDATA, true))
       throw std::runtime_error("Unable to find app data directory");
     appDataPath.assign(pathBuffer.get());
   }
-  return std::wstring(appDataPath) + L"\\AdblockPlus";

[Wladimir Palant, 2013/05/23 14:25:01]

appDataPath already is a wstring, no need to construct a new string here.

[Felix Dahlke, 2013/05/23 19:10:44]

Done.

+  return appDataPath + L"\\AdblockPlus";
 }
 
 std::auto_ptr<AdblockPlus::FilterEngine> CreateFilterEngine()
 {
   // TODO: Pass appInfo in, which should be sent by the client
   AdblockPlus::JsEnginePtr jsEngine = AdblockPlus::JsEngine::New();
-  std::string dataPath = ToString(GetAppDataPath());
+  std::string dataPath = ToUtf8String(GetAppDataPath());
   dynamic_cast<AdblockPlus::DefaultFileSystem*>(jsEngine->GetFileSystem().get())->SetBasePath(dataPath);
   std::auto_ptr<AdblockPlus::FilterEngine> filterEngine(new AdblockPlus::FilterEngine(jsEngine));
   std::vector<AdblockPlus::SubscriptionPtr> subscriptions = filterEngine->FetchAvailableSubscriptions();
   // TODO: Select a subscription based on the language, not just the first one.
   //       This should ideally be done in libadblockplus.
   AdblockPlus::SubscriptionPtr subscription = subscriptions[0];
   subscription->AddToList();
   return filterEngine;
 }
 
@@ skipping 42 matching lines @@
     AutoHandle thread(CreateThread(0, 0, ClientThread, static_cast<LPVOID>(pipe), 0, 0));
     if (!thread.get())
     {
       LogLastError("CreateThread failed");
       return 1;
     }
   }
 
   return 0;
 }