Fix named pipe security on Windows XP

src/shared/Communication.cpp

 #include <Windows.h>
 #include <Lmcons.h>
 #include <Sddl.h>
 #include <aclapi.h>
 #include <strsafe.h>
 
 #include "AutoHandle.h"
 #include "Communication.h"
 #include "Utils.h"
 
@@ skipping 176 matching lines @@
     OpenProcessToken(GetCurrentProcess(), TOKEN_READ, token);
     
     if (IsWindowsVistaOrLater())
     {
       std::auto_ptr<SID> logonSid = GetLogonSid(token);
       // Create a SECURITY_DESCRIPTOR that has both Low Integrity and allows access to all AppContainers
       // This is needed since IE likes to jump out of Enhanced Protected Mode for specific pages (bing.com)
       std::auto_ptr<SECURITY_DESCRIPTOR> securityDescriptor = CreateSecurityDescriptor(logonSid.get());
       securityAttributes.lpSecurityDescriptor = securityDescriptor.release();
       sharedSecurityDescriptor.reset(static_cast<SECURITY_DESCRIPTOR*>(securityAttributes.lpSecurityDescriptor));
-
-      pipe = CreateNamedPipeW(pipeName.c_str(),  PIPE_ACCESS_DUPLEX, PIPE_TYPE_MESSAGE | PIPE_READMODE_MESSAGE | PIPE_WAIT,
-        PIPE_UNLIMITED_INSTANCES, bufferSize, bufferSize, 0, &securityAttributes);
-    }
-    else
-    {
-      pipe = CreateNamedPipeW(pipeName.c_str(),  PIPE_ACCESS_DUPLEX, PIPE_TYPE_MESSAGE | PIPE_READMODE_MESSAGE | PIPE_WAIT,
-        PIPE_UNLIMITED_INSTANCES, bufferSize, bufferSize, 0, &securityAttributes);

[Felix Dahlke, 2014/06/24 12:25:05]

This is the exact same "CreateNamedPipeW" done in the if body above. We can move
it below the if body and get rid of the else branch here.

-    }
+    }
+    pipe = CreateNamedPipeW(pipeName.c_str(),  PIPE_ACCESS_DUPLEX, PIPE_TYPE_MESSAGE | PIPE_READMODE_MESSAGE | PIPE_WAIT,
+      PIPE_UNLIMITED_INSTANCES, bufferSize, bufferSize, 0, &securityAttributes);
   }
   else
   {
     pipe = CreateFileW(pipeName.c_str(), GENERIC_READ | GENERIC_WRITE, 0, 0, OPEN_EXISTING, 0, 0);
     if (pipe == INVALID_HANDLE_VALUE && GetLastError() == ERROR_PIPE_BUSY)
     {
       if (!WaitNamedPipeW(pipeName.c_str(), 10000))
         throw PipeBusyError();
 
       pipe = CreateFileW(pipeName.c_str(), GENERIC_READ | GENERIC_WRITE, 0, 0, OPEN_EXISTING, 0, 0);
@@ skipping 49 matching lines @@
   return Communication::InputBuffer(stream.str());
 }
 
 void Communication::Pipe::WriteMessage(Communication::OutputBuffer& message)
 {
   DWORD bytesWritten;
   std::string data = message.Get();
   if (!WriteFile(pipe, data.c_str(), static_cast<DWORD>(data.length()), &bytesWritten, 0))
     throw std::runtime_error("Failed to write to pipe");
 }