sigaction's signal handler not called in child process

I've a program, which installs a signal handler for SIGSEGV. In signal handler ( I try to catch crash ) I restart my application.

But when my application is resurrected it doesn't handle SIGSEGV anymore.

Here's an example:

#include <stdio.h>
#include <stdlib.h>
#include <signal.h>
#include <unistd.h>

const char * app = 0;

void sig_handler(int signo)
{
    puts("sig_handler");

    const pid_t p = fork();

    if (p == 0)
    {
        printf("Running app %s\n", app);
        execl(app, 0);
    }

    exit(1);
}


int main(int argc, char** argv)
{
    app = argv[0];

    struct sigaction act;
    sigemptyset(&act.sa_mask);

    act.sa_handler = sig_handler;
    act.sa_flags = 0;

    const int status = sigaction(SIGSEGV, &act, 0) == 0;     
    printf("signaction = %d\n", status);

    sleep(5);

    int* a = 0;
    int b = *a;

    return 0;
}

what I get in output is:

./signals 
signaction = 1
sig_handler
Running app ./signals
signaction = 1

So I can see sighandler was set in right way, but resurrected app simply crashed silently.

What am I missing?