/*
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/.
 *
 * Copyright 2019, Danny Robson <danny@nerdcruft.net>
 */

#include "crash.hpp"

#include "../backtrace.hpp"
#include "../posix/except.hpp"
#include "../map/fixed.hpp"

#include <signal.h>

#include <iostream>
#include <cstring>


///////////////////////////////////////////////////////////////////////////////
static constexpr
int to_handle[] = {
    SIGBUS,
    SIGFPE,
    SIGILL,
    SIGSEGV,
    SIGABRT,
};


auto constexpr handled_count = std::size (to_handle);


cruft::map::fixed<handled_count, int, struct sigaction> s_old_handlers;


//-----------------------------------------------------------------------------
void dumping_handler (int sig, siginfo_t *info, void *ucontext)
{
    std::clog << cruft::backtrace () << '\n';

    // Forward the signal to the previously registered handler
    auto const next_handler = s_old_handlers.at (sig);
    if (next_handler.sa_flags & SA_SIGINFO)
        next_handler.sa_sigaction (sig, info, ucontext);
    else
        next_handler.sa_handler (sig);
}


///////////////////////////////////////////////////////////////////////////////
void
cruft::debug::init_crash_handler ()
{
    struct sigaction new_handler {};
    memset (&new_handler, 0, sizeof (new_handler));
    new_handler.sa_flags = SA_SIGINFO;
    new_handler.sa_sigaction = dumping_handler;

    for (auto const sigid: to_handle) {
        cruft::posix::error::try_code (
            sigaction (
                sigid,
                &new_handler,
                &s_old_handlers[sigid]
            )
        );
    }
}