rov_posixsignal2c++exception001.cpp - test whether a POSIX signal can be turned into a C++ exception
Posted by Anonymous on Tue 7th Apr 2026 14:59
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/*
 * rov_posixsignal2c++exception001.cpp - test whether a POSIX signal can be
 * turned into a C++ exception
 *
 * Compile with $ g++ -std=c++17 -g -Wall -Wextra rov_posixsignal2c++exception001.cpp #
 *
 * Written by Roland Mainz <roland.mainz@rovema.de>
 */

#include <cstdio>
#include <csignal>
#include <exception>
#include <string>
#include <cstring>
#include <stdexcept>

class posix_signal_exception : public std::exception {
private:
    int sig_num;
    std::string msg;

public:
    explicit posix_signal_exception(int signum) : sig_num(signum) {
        /* FIXME: We should store the whole siginfo() data here */
        msg = "Caught POSIX signal: " + std::to_string(signum) +
              " (" + strsignal(signum) + ")";
    }

    /*[[nodiscard]]*/ const char* what() const noexcept override {
        return msg.c_str();
    }

    /*[[nodiscard]]*/ int signum() const noexcept {
        return sig_num;
    }
};

extern "C"
void signal_handler(int signum) {
    throw posix_signal_exception(signum);
}

void setup_signal_handler(int signum) {
    struct sigaction sa;
    (void)memset(&sa, 0, sizeof(sa));

    sa.sa_handler = signal_handler;
    (void)sigemptyset(&sa.sa_mask);

    sa.sa_flags = SA_NODEFER;

    if (sigaction(signum, &sa, NULL) == -1) {
        throw std::runtime_error("setup_signal_handler: Failed to setup signal handler.");
    }
}

int main(int ac, char *av[])
{
    (void)ac;
    (void)av;

    try {
        setup_signal_handler(SIGFPE);

        (void)fprintf(stderr, "Signal handler installed. Triggering a divide-by-zero...\n");

        volatile int zero = 0;
        int result = 10 / zero;

        (void)fprintf(stderr, "Result: %d\n", result);

    } catch (const posix_signal_exception &e) {
        (void)fprintf(stderr, "#### posix_signal_exception caught\n");
        (void)fprintf(stderr, "Message: '%s'\n", e.what());
        (void)fprintf(stderr, "Signal Number: %d\n", e.signum());
    } catch (const std::exception& e) {
        (void)fprintf(stderr, "#### Standard exception caught: '%s'\n", e.what());
    }

    return EXIT_SUCCESS;
}