glibc-2.3.x: SIGRTMIN & kern_has_rtsigs() *WITHOUT* -lpthread

[Chris Wedgwood <cw@f00f.org>]

Hi there,

I'm not *who* is at fault here (quite possibly me), but Debian 'sid'
now uses glibc-2.3.x instead of glibc-2.2.x.

Bug: SIGRTMIN/__libc__current_sigrtmin() under glibc-2.2.x and
glibc-2.3.x work differently.


Under glibc-2.2.x you can build an application and *NOT* link with
-lpthread and have SIGRTMIN (ie. __libc__current_sigrtmin() return
sane value), under glibc-2.3.x you cannot do this.   For glibc-2.3.x
you must use -lpthread which over-rides kernel_has_rtsigs().

This means any any applications using glibc-2.3.x which are not
compiled -lpthread may crash as they will get SIGIO unexpectedly in
places... and that's not very cool.

I checked the source and don't actually see why this works in 2.2.x
and not 2.3.x; the code involved hasn't changed, but maybe when
linking with 2.2.x I get a different kernel_has_rtsigs() andhow?


   --cw

P.S. Is there a defined glibc API for allocation and management of
     realtime signals?   I don't see one which means using them from
     libraries and simialr is not an option.