pthread_sigaction() ?

[Xavier Roche]

Hi folks,

POSIX defines pthread_kill(pthread_t thread, int sig) to deliver a 
signal to a specific thread.

But there is no way to handle it properly without overriding the global 
signal handler ; ie. a given thread can not override locally the signal 
handler for a specific purpose without a tight cooperation with the rest 
of the process. And even with a cooperative process, handling a signal 
differently for a given thread requires some acrobatic code (locking is 
in theory forbidden as non signal-safe for example)

I was wondering why such function does not exist yet:

int pthread_sigaction_np(int signum, const struct sigaction *act,
                          struct sigaction *oldact);

(or
int pthread_sigaction_np(pthread_t thread, int signum,
                          const struct sigaction *act,
                          struct sigaction *oldact);
?)

Some considerations regarding priority of handlers would have to  be 
solved first ; it. sigation() handler vs. pthread_sigaction() handler 
(the two could override each other depending on the ordering, for example)

Any thoughts on this ? No use case maybe ? [my use case was the ability 
to locally handle signals to be able to siglongjmp() back to a defined 
state on a given code section, without modifying the global signal handler]


(*) 
<http://pubs.opengroup.org/onlinepubs/9699919799/functions/pthread_kill.html>