Change signal mask after vfork/clone system call

From: Gregory Giguashvili
Date: Tue Oct 19 2010 - 04:04:59 EST


For new processes created by vfork, while signals are blocked using pthread_sigmask: is there a way in a multi-threaded parent to safely unblock signals before the new process is started? Does pthread_atfork like functionality exist for vfork-ed processes maybe?

Ideally, the following code should work, except we're not allowed to call anything in the child process besides exec family of functions.

sigmask_t new;
sigmask_t old;
sigaddset (&new, SIGCHLD);
pthread_sigmask (SIG_BLOCK, &new, &old);

switch (vfork ()) {
case 0: // parent
break;
case -1: // error
break;
default: // child
pthread_sigmask (SIG_SETMASK, &old, NULL);
execv (...);
_exit (-1);
}

Finally, if using fork should be efficient for starting processes from applications with heavy VM/RSS memory footprint, this question becomes obsolete.

Thanks
Giga

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