Re: Official Linux system wrapper library?

Florian Weimer
2018-11-11T10:30:38Z

* Willy Tarreau:

> On Sun, Nov 11, 2018 at 07:55:30AM +0100, Michael Kerrisk (man-pages) wrote:
>> [1] https://sourceware.org/bugzilla/show_bug.cgi?id=6399 is a
>> longstanding example.
>
> This one was a sad read and shows that applications will continue to
> suffer from glibc's prehistorical view on operating systems and will
> continue to have to define their own syscall wrappers to exploit the
> full potential of the modern operating systems they execute on.

What's modern about a 15-bit thread identifier?

I understand that using this interface is required in some cases (which
includes some system calls for which glibc does provide wrappers), but I
assumed that it was at least understood that these reusable IDs for
tasks were an extremely poor interface. Aren't the resulting bugs
common knowledge?

> This reminds me when one had to write their own spinlocks and atomics
> many years ago. Seeing comments suggesting an application should open
> /proc/$PID makes me really wonder if people actually want to use slow
> and insecure applications designed this way.

I don't understand. If you want a non-reusable identifier, you have to
go through the /proc interface anyway. I think the recommendation is to
use the PID/start time combination to get a unique process identifier or
something like that.

I wanted to add gettid to glibc this cycle, but your comments suggest to
me that if we did this, we'd likely never get a proper non-reusable
thread identifier from the kernel. So I'm not sure what do anymore.

Thanks,
Florian