Question

I have to write a function that retrieves some information about some signal handling status. That is if there is a specific handler or the signal is ignored, the signal which are blocked and what flags are activated. In order to do this I use sigaction function. Here is my code:

void show_signal_info(int signal_number){
    struct sigaction s;
    int nomask=1;

    if(sigaction(signal_number, NULL, &s) == -1){
        perror("Error getting information of signal");
    }else{
        printf("Signal name: %s\n",signal_name(signal_number));

        printf("Signal mask: ");
        for(i=0; i<32; i++){
            if(sigismember(s.sa_mask,i) == 1)
                printf("%s ",signal_name(i);
        printf("%s",nomask ? "None\n" : "\n");

        if(s.sa_handler == SIG_DFL)
             printf("Default\n");
        else if (s.sa_handler == SIG_IGN)
             printf("Ignored\n");
        else
             printf("Handler\n");

        [...]

    }
}

The problem is that I dont know how to check what flags are on with s.sa_flags? There is some macros similar to those I can use with wait() function or there is other way to do it?

Answer 1

The problem is that I dont know how to check what flags are on with
s.sa_flags

You can test bits, for example:

if (s.sa_flags & SA_RESTART)
    ....