Externally disabling signals for a Linux program

Question

On Linux, is it possible to somehow disable signaling for programs externally... that is, without modifying their source code?

Context:

Answer 1

The process signal mask is inherited across exec, so you can simply write a small wrapper program that blocks SIGINT and executes the target:

#include 
#include 
#include 

int main(int argc, char *argv[])
{
        sigset_t sigs;

        sigemptyset(&sigs);
        sigaddset(&sigs, SIGINT);
        sigprocmask(SIG_BLOCK, &sigs, 0);

        if (argc > 1) {
                execvp(argv[1], argv + 1);
                perror("execv");
        } else {
                fprintf(stderr, "Usage: %s  [args...]\n", argv[0]);
        }
        return 1;
}

If you compile this program to noint, you would just execute ./noint ./y.

As ephemient notes in comments, the signal disposition is also inherited, so you can have the wrapper ignore the signal instead of blocking it:

#include 
#include 
#include 

int main(int argc, char *argv[])
{
        struct sigaction sa = { 0 };

        sa.sa_handler = SIG_IGN;
        sigaction(SIGINT, &sa, 0);

        if (argc > 1) {
                execvp(argv[1], argv + 1);
                perror("execv");
        } else {
                fprintf(stderr, "Usage: %s  [args...]\n", argv[0]);
        }
        return 1;
}

(and of course for a belt-and-braces approach, you could do both).