#include <inttypes.h>
#include <signal.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>

#define ADD_SIGNAL(signal)      { signal, #signal }

const struct {
        int                     signal;
        const char*     name;
} kSignals[] = {
        ADD_SIGNAL(SIGHUP),
        ADD_SIGNAL(SIGINT),
        ADD_SIGNAL(SIGQUIT),
        ADD_SIGNAL(SIGILL),
        ADD_SIGNAL(SIGCHLD),
        ADD_SIGNAL(SIGABRT),
        ADD_SIGNAL(SIGPIPE),
        ADD_SIGNAL(SIGFPE),
        ADD_SIGNAL(SIGKILL),
        ADD_SIGNAL(SIGSTOP),
        ADD_SIGNAL(SIGSEGV),
        ADD_SIGNAL(SIGCONT),
        ADD_SIGNAL(SIGTSTP),
        ADD_SIGNAL(SIGALRM),
        ADD_SIGNAL(SIGTERM),
        ADD_SIGNAL(SIGTTIN),
        ADD_SIGNAL(SIGTTOU),
        ADD_SIGNAL(SIGUSR1),
        ADD_SIGNAL(SIGUSR2),
        ADD_SIGNAL(SIGWINCH),
        ADD_SIGNAL(SIGKILLTHR),
        ADD_SIGNAL(SIGTRAP),
        {-1, NULL}
};

#define ADD_SA_FLAG(flag)       { flag, #flag }


const struct {
        int                     flag;
        const char*     name;
} kSigActionFlags[] = {
        ADD_SA_FLAG(SA_NOCLDSTOP),
#ifdef SA_NOCLDWAIT
                ADD_SA_FLAG(SA_NOCLDWAIT),
#endif
#ifdef SA_RESETHAND
        ADD_SA_FLAG(SA_RESETHAND),
#endif
#ifdef SA_NODEFER
        ADD_SA_FLAG(SA_NODEFER),
#endif
#ifdef SA_RESTART
        ADD_SA_FLAG(SA_RESTART),
#endif
#ifdef SA_ONSTACK
        ADD_SA_FLAG(SA_ONSTACK),
#endif
#ifdef SA_SIGINFO
        ADD_SA_FLAG(SA_SIGINFO),
#endif
        {0, NULL}
};


int
main(int argc, const char* const* argv)
{
        // print pid, process group
        printf("process id:       %d\n", (int)getpid());
        printf("parent id:        %d\n", (int)getppid());
        printf("process group:    %d\n", (int)getpgrp());
        printf("fg process group: %d\n", (int)tcgetpgrp(STDOUT_FILENO));

        // print signal mask
        sigset_t signalMask;
        sigprocmask(SIG_BLOCK, NULL, &signalMask);
        printf("blocked signals:  ");
        bool printedFirst = false;
        for (int i = 0; kSignals[i].name; i++) {
                if (sigismember(&signalMask, kSignals[i].signal)) {
                        if (printedFirst) {
                                printf(", ");
                        } else
                                printedFirst = true;
                        printf("%s", kSignals[i].name);
                }
        }
        printf("\n");

        // print signal handlers
        printf("signal handlers:\n");
        for (int i = 0; kSignals[i].name; i++) {
                struct sigaction action;
                sigaction(kSignals[i].signal, NULL, &action);

                // signal name
                int signalNameSpacing = 10 - (int)strlen(kSignals[i].name);
                if (signalNameSpacing < 0)
                        signalNameSpacing = 0;
                printf("  %s:%*s ", kSignals[i].name, signalNameSpacing, "");

                // signal handler
                if (action.sa_handler == SIG_DFL)
                        printf("SIG_DFL");
                else if (action.sa_handler == SIG_IGN)
                        printf("SIG_IGN");
                else if (action.sa_handler == SIG_ERR)
                        printf("SIG_ERR");
                else
                        printf("%p", action.sa_handler);

                printf(" (");

                // flags
                printedFirst = false;
                for (int i = 0; kSigActionFlags[i].name; i++) {
                        if (action.sa_flags & kSigActionFlags[i].flag) {
                                if (printedFirst) {
                                        printf(", ");
                                } else
                                        printedFirst = true;
                                printf("%s", kSigActionFlags[i].name);
                        }
                }
                printf(")\n");
        }
        

        return 0;
}