Bug 25132

I want to block a signal by sigprocmask, but the signal is not blocked.

Following description is for SIGTERM signal.

In pthread library, signal is trapped by thread_sig_handler(). If
the signal mask is set, the signal blocks in the handler. But
thread_init() sets thread_sig_hander() as signal handler only for
_SCHED_SIGNAL, SIGINFO and SIGCHLD. When the SIGTERM signal is caught,
the signal is processed in kernel and default handler (kill process)
is called.

If I set some signal hander for SIGTERM, then thread_sig_handler() is
used as the signal handler for SIGTERM. Then the signal mask is correctly
used.

How-To-Repeat: Compile this program with -pthread option. For example,
  cc test.c -pthread
This program should block 'SIGTERM' signal, but 'kill -TERM pid' kills
this program.

#include <signal.h>

int main()
{
        sigset_t tset;
        sigemptyset(&tset);
        sigaddset(&tset, SIGTERM);
        sigprocmask(SIG_BLOCK,&tset,NULL);
        while(1) ;
}

But this program correctly blocks the signal.

#include <signal.h>

void handler(int sig) {
        _exit(0);
}

int main()
{
        sigset_t tset;
        sigemptyset(&tset);
        sigaddset(&tset, SIGTERM);
        sigprocmask(SIG_BLOCK,&tset,NULL);
        signal(SIGTERM,handler);
        while(1) ;
}