LinuxQuestions.org - How to reinstall a signal handler after exec ( Strange behaviour in signal handling )

Hi

The following program is born totally out of curiosity and as far as i can think has no real use ? (Kindly point out if i am wrong anywhere)
I am trying to install signal handler for SIGSEGV.

Code:

#include<iostream>

#include<unistd.h>

#include<signal.h>

using namespace std;

void signal_handler(int n)

{

    cout<<"\nSEGMENTATION FAULT OCCURRED I AM LOADING THE PROCESS AGAIN"<<endl;

    execv("a.out",0);

}

int main()

{

    struct sigaction s;

    s.sa_handler=signal_handler;

    cout<<"\nTHIS IS THE MAIN OF THE PROCESS"<<endl;

    if(sigaction(SIGSEGV,&s,0))

    {

        cout<<"\nINSTALLATION OF SIGNAL HANDLER FAILED"<<endl;

    }

    else

    {

        cout<<"\nSIGNAL HANDLER SUCCESSFULLY INSTALLED"<<endl;

    }

    int* p=0;

    *p=6;

        cout<<"\nBefore return"<<endl;

    return 0;

}

The thing is that i want to handle the signal SIGSEGV and then exec the same process(executable a.out).

exec i guess clears all the signal dispositions and reinstalls the default signal dispositions. But since the new process starts from the main, i can again reinstall the signal handler for SIGSEGV( and infact the output verifies it but still i get the following behaviour which i don't expect)

Quote:

me@battleaXe:~/programs$ g++ signal_handling.cpp
me@battleaXe:~/programs$ ./a.out

THIS IS THE MAIN OF THE PROCESS

SIGNAL HANDLER SUCCESSFULLY INSTALLED

SEGMENTATION FAULT OCCURRED I AM LOADING THE PROCESS AGAIN

THIS IS THE MAIN OF THE PROCESS

SIGNAL HANDLER SUCCESSFULLY INSTALLED
Segmentation fault
me@battleaXe:~/programs$

My expected behaviour is that the process should keep on segfaulting and keep reloading itself infinitely. I does happen for the first time but from next time onwards it doesn't( as you can clearly see in the output )

I have googled for more than 2 hours without any satisfactory answer.
I also learned from somewhere that when a signal handler is being executed, that signal is masked i.e SIGSEGV in my case would be masked and when i do exec in the signal handler, the signal SIGSEGV would remain masked in the execed process. But if that is the case then i should never get "Segmentation fault" because if SIGSEGV gets masked, it won't be delivered and in that case my program should execute completely, isn't it ? But infact the statement "Before return" never gets printed as you can see from the output.
May be i am missing something and there could be some flaw in the way i have understood things to be.

Waiting eagerly for your response.

Thanks & Regards
lali.cpp