/* IRCfs - IRC FileServ for *nix.
 * Copyright (C) 2002  Nick 'Zaf' Clifford <zaf@nrc.co.nz>
 * For licensing details, refer to the LICENSE file in the source 
 * code directory.
 *
 */
#define _GNU_SOURCE
#include <string.h>
#include <signal.h>
#include "runtime.h"
#include "crash.h"
#include "config.h"
#ifdef ENABLE_DEBUG
#define DUMP_CORE

#if defined(HAVE_GETRLIMIT) && HAVE_SYS_RESOURCE_H
#include <sys/resource.h>
#endif
#endif
#ifdef HAVE_BACKTRACE
#include <execinfo.h>
#endif

volatile sig_atomic_t crash_fatal_error_in_progress = 0;
volatile sig_atomic_t crash_debugger_running = 0;

void signal_fatal_handler(int signum);

#ifndef HAVE_STRSIGNAL
char *strsignal(int signum)
{
	return "Unknown - no strsignal";
}
#endif

void signal_setup()
{
	struct sigaction sa;

	sigaction (SIGTRAP, NULL, &sa);
	if (sa.sa_handler != SIG_DFL) {
		/* Signal Trap is set, so we'll defer to the debugger. */
		fprintf(stderr,"Hello debugger!\n");
		crash_debugger_running = 1;
	} else {
		sa.sa_flags = 0;
		sigemptyset(&sa.sa_mask);
	
		sa.sa_handler = signal_fatal_handler;

#ifdef SIGSEGV
		sigaction(SIGSEGV,&sa,NULL);
#endif
#ifdef SIGILL
		sigaction(SIGILL,&sa,NULL);
#endif
#ifdef SIGFPE
		sigaction(SIGFPE,&sa,NULL);
#endif
#ifdef SIGBUS
		sigaction(SIGBUS,&sa,NULL);
#endif
#ifdef SIGTRAP
		sigaction(SIGTRAP,&sa,NULL);
#endif
#ifdef SIGEMT
		sigaction(SIGEMT,&sa,NULL);
#endif
#ifdef SIGSYS
		sigaction(SIGSYS,&sa,NULL);
#endif
	}
	/* Signals we ignore */
	
	sa.sa_flags = 0;
	sigemptyset(&sa.sa_mask);
	sa.sa_handler = SIG_IGN;
#ifdef SIGINFO
	sigaction(SIGINFO,&sa,NULL);
#endif
#ifdef SIGWINCH
	sigaction(SIGWINCH,&sa,NULL);
#endif
#ifdef SIGUSR1
	sigaction(SIGUSR1,&sa,NULL);
#endif
#ifdef SIGUSR2
	sigaction(SIGUSR2,&sa,NULL);
#endif
#ifdef SIGPIPE
	sigaction(SIGPIPE,&sa,NULL);
#endif
#ifdef SIGIO
	sigaction(SIGIO,&sa,NULL);
#endif
#ifdef SIGALRM
	sigaction(SIGALRM,&sa,NULL);
#endif
	/* Signals we ignore, but shouldn't (eg TODO) */
#ifdef SIGXFSZ
	sigaction(SIGXFSZ,&sa,NULL); /* Exceeded file size limits */
#endif
#ifdef SIGXCPU
	sigaction(SIGXCPU,&sa,NULL); /* Exceeded CPU limits */
#endif
#ifdef SIGLOST
	sigaction(SIGLOST,&sa,NULL); /* Lost an NFS resource */
#endif
}


int setup_core_dump()
{
#if defined(DUMP_CORE) && defined(HAVE_GETRLIMIT) && defined(HAVE_SETRLIMIT)
	struct rlimit rl;
#ifndef RLIM_INFINITY
/* If RLIM_INIFINITY isn't defined try BSDs OFILE */
#ifdef RLIMIT_OFILE
#define RLIM_INFINITY RLIM_OFILE
#else
#define RLIM_INFINITY 0xFFFF
#endif
#endif
	if (getrlimit(RLIMIT_CORE,&rl) == -1) {
		return -1;
	}
	if (rl.rlim_cur > 0 || rl.rlim_cur == RLIM_INFINITY) {
		return 0;
	}
	rl.rlim_max = RLIM_INFINITY;
	if (setrlimit(RLIMIT_CORE,&rl) == -1) {
		return -1;
	}
	return 0;
#else
	return -1;
#endif
}


void signal_fatal_handler(int signum)
{
	static char buffer[255];
	const char *cp;
#ifdef HAVE_BACKTRACE
	static void *backtrace_buffer[91];
	int n;
#endif
	
	/* Since this handler is established for more than one kind of signal, 
	 * it might still get invoked recursively by delivery of some other 
	 * kind of signal.  Use a static variable to keep track of that. 
	 * Raising the signal again invokes the signals default behaviour
	 */ 
	if (crash_fatal_error_in_progress)
		raise (signum);
	crash_fatal_error_in_progress = 1;

	/* It *should* be safe to write to stderr since it isn't used
	 * anywhere else in the program
	 */
	snprintf(buffer,sizeof(buffer)-1,"Received fatal signal %d: ",
			signum);
	write(2,buffer,strlen(buffer));
	cp = strsignal(signum);
	write(2,cp,strlen(cp));
	write(2,"\n",1);
#ifdef HAVE_BACKTRACE
	n = backtrace(backtrace_buffer,90);
	if (n == -1) {
		snprintf(buffer,sizeof(buffer)-1,
				"backtrace() returned -1 error=%d:",
				errno);
		write(2,buffer,strlen(buffer));
		cp = strerror(errno);
		write(2,cp,strlen(cp));
		write(2,"\n",1);
	} else {
		cp = "Generating backtrace:\n";
		write(2,cp,strlen(cp));
		backtrace_symbols_fd(backtrace_buffer,n,2);
		cp = "Done\n";
		write(2,cp,strlen(cp));
	}
#else
	cp = "No backtrace support on this system\n";
	write(2,cp,strlen(cp));
#endif

	abort();	
}