/* See LICENSE file for copyright and license details. */
#include <errno.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define UNW_LOCAL_ONLY
#include <elfutils/libdwfl.h>
#include <libunwind.h>


static const int full_paths = 0;


static void
dump_stack(ucontext_t *ucontext)
{
	int saved_errno = errno, lineno;
	unw_word_t rip;
	unw_cursor_t cursor;
	char *debuginfo_path = NULL;
	Dwarf_Addr ip;
	Dwfl_Callbacks callbacks;
	Dwfl *dwfl = NULL;
	Dwfl_Line *line = NULL;
	Dwfl_Module *module = NULL;
	const char *filename = NULL, *p;
	const char *funcname = NULL;
	int first = 1;

	if (unw_init_local2(&cursor, ucontext, UNW_INIT_SIGNAL_FRAME))
		goto out;

	memset(&callbacks, 0, sizeof(callbacks));

	callbacks.find_elf       = dwfl_linux_proc_find_elf;
	callbacks.find_debuginfo = dwfl_standard_find_debuginfo;
	callbacks.debuginfo_path = &debuginfo_path;


	dwfl = dwfl_begin(&callbacks);

	if (dwfl) {
		if (dwfl_linux_proc_report(dwfl, getpid()) ||
		    dwfl_report_end(dwfl, NULL, NULL)) {
			dwfl_end(dwfl);
			dwfl = NULL;
		}
	}

	do {
		if (unw_get_reg(&cursor, UNW_REG_IP, &rip))
			break;
		ip = (Dwarf_Addr)rip;

		if (dwfl) {
			module   = dwfl_addrmodule(dwfl, ip);
			funcname = module ? dwfl_module_addrname(module, ip) : NULL;
			line     = dwfl_getsrc(dwfl, ip);
			if (line) {
				filename = dwfl_lineinfo(line, &(Dwarf_Addr){0},
				                         &lineno, NULL, NULL, NULL);
				if (!full_paths && (p = strrchr(filename, '/')))
					filename = &p[1];
			}
		}

		fprintf(stderr, "%s 0x%016"PRIxPTR": %s",
		        first ? "crashed at" : "        by",
			(uintptr_t)ip,
		        funcname ? funcname : "???");
		first = 0;
		if (line)
			fprintf(stderr, " (%s:%i)\n", filename, lineno);
		else
			fprintf(stderr, "\n");

	} while (unw_step(&cursor) > 0);

	if (dwfl)
		dwfl_end(dwfl);
out:
	errno = saved_errno;
}


static void
stack_dumper(int sig, siginfo_t *info, void *ucontext)
{
	(void) sig;
	(void) info;
	dump_stack(ucontext);
}


int
main(void)
{
	struct sigaction sa;

	memset(&sa, 0, sizeof(sa));
	sa.sa_sigaction = &stack_dumper;
	sa.sa_flags = (int)(SA_RESETHAND | SA_SIGINFO);

#if 1
	{
		static volatile int *null = NULL;
		sigaction(SIGSEGV, &sa, NULL);
		return *null;
	}
#else
	sigaction(SIGABRT, &sa, NULL);
	abort();
	return 0;
#endif
}