OpenThread() Returns NULL Win32
c++, multithreading, visual-c++, winapi, windows
Solution
Maybe you're asking for too much access (`THREAD_ALL_ACCESS`), though I'd think that you'd have pretty much all permissions to your own thread. Try reducing the access to what you really need.
What does `GetLastError()` return?
Update:
Take a look at this comment from MSDN:
Windows Server 2003 and Windows XP/2000: The size of the `THREAD_ALL_ACCESS` flag increased on Windows Server 2008 and Windows Vista. If an application compiled for Windows Server 2008 and Windows Vista is run on Windows Server 2003 or Windows XP/2000, the `THREAD_ALL_ACCESS` flag is too large and the function specifying this flag fails with `ERROR_ACCESS_DENIED`. To avoid this problem, specify the minimum set of access rights required for the operation. If `THREAD_ALL_ACCESS` must be used, set `_WIN32_WINNT` to the minimum operating system targeted by your application (for example, `#define _WIN32_WINNT _WIN32_WINNT_WINXP` ). For more information, see Using the Windows Headers
Problem
I feel like there is an obvious answer to this, but it's been eluding me. I've got some legacy code in C++ here that breaks when it tries to call OpenThread(). I'm running it in Visual C++ 2008 Express Edition. The program first gets the ThreadID of the calling thread, and attempts to open it, like so: ThreadId threadId = IsThreaded() ? thread_id : ::GetCurrentThreadId(); HANDLE threadHandle = OpenThread(THREAD_ALL_ACCESS, FALSE, threadId); Now here's what I don't understand: if the thread ID is the current thread's ID, isn't it already open? Could that be why it's returning NULL? Any feedback would be appreciated.