Re: Thread local storage problem, and fix

[Thomas Pfaff <tpfaff@gmx.net>]

On Wed, 22 Aug 2001, Phil Frisbie, Jr. wrote:

> While converting the simple per thread error storage in HawkNL over to
> POSIX and
> native Windows thread local storage, I came across some problems. I
> store a
> HawkNL error code for the thread, and if it is a Winsock error I set the
> error
> to NL_SOCKET_ERROR so the application can retrieve the real error code.
> But
> Winsock errors seemed to be cleared whenever pthread_getspecific() was
> called.
> They were also cleared by calling the native Windows TlsGetValue().
>
> So, I looked at the Pthreads-win32 source code for
> pthread_getspecific(), and
> found this:
>
> void *
> pthread_getspecific (pthread_key_t key)
> {
>   int lasterror = GetLastError();
>
>   void *ptr = TlsGetValue (key->key);
>
>   SetLastError( lasterror );
>
>   return ptr;
> }
>
> I guess someone already found out TlsGetValue() clears out the last
> error, but
> they did not know it also clears out the last Winsock error. The fix is
> to
> change the code to:
>
> void *
> pthread_getspecific (pthread_key_t key)
> {
>   int lasterror = GetLastError();
>   int lastWSAerror = WSAGetLastError();
>
>   void *ptr = TlsGetValue (key->key);
>
>   SetLastError( lasterror );
>   WSASetLastError( lastWSAerror );
>
>   return ptr;
> }
>
> I have added a work around to HawkNL until this gets fixed.
>
>
> Phil Frisbie, Jr.
> Lead Developer, Hawk Software
> http://www.hawksoft.com
>

strange,

at least on NT4 the WSALastError equals to Win32 LastError when i used
Winsock2, so i did not saved it too.

I will have a look if you tell me your platform.

Greetings,

Thomas