Re: How to detect NPTL at compile time

Jakub Jelinek wrote:
> On Fri, Apr 04, 2003 at 02:51:51PM -0800, Wan-Teh Chang wrote:
> 
>>Red Hat Linux 9 ships with the NPTL.  Our code
>>contains workarounds for LinuxThreads, and I
>>want to disable the workarounds if we are compiling
>>against NPTL.  How do I detect whether the pthread
>>library is LinuxThreads or NPTL at compile time?
>>Can I use the glibc version number to determine
>>that (i.e., NPTL if glibc 2.3 or higher)?

RH-9 has both NPTL and LinuxThreads. Your program could run
with either library. You should detect library type and
disable LT workarounds at runtime, not compile time.

> 
> 
> No.
> 
> int isnptl (void)
> {
>   size_t n = confstr (_CS_GNU_LIBPTHREAD_VERSION, NULL, 0);
>   if (n > 0)
>     {
>       char *buf = alloca (n);
>       confstr (_CS_GNU_LIBPTHREAD_VERSION, buf, n);
>       if (strstr (buf, "NPTL"))
>         return 1;
>     }
>   return 0;
> }
> 

As pointed out by another email today, apparently confstr()
doesn't work correctly on RH-9. It always returns "NPTL 0.29"
even I'm running with LinuxThreads. Any workaround for that?

thanks,
-hui