/*
crashhandler.c - advanced crashhandler
Copyright (C) 2016 Mittorn

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.
*/

#if HAVE_LIBBACKTRACE
#include <signal.h>
#include "common.h"
#include "backtrace.h"
#include "input.h"

static struct backtrace_state *g_bt_state;
static qboolean enable_libbacktrace;

static void Sys_BacktraceError( void *data, const char *msg, int errnum )
{
	if( errnum < 0 )
	{
		Con_Printf( S_ERROR "no symbol info, no libbacktrace\n" );
		return;
	}

	Con_Printf( S_ERROR "libbacktrace error: %s (%d)\n", msg, errnum );

	enable_libbacktrace = false;
}

struct print_data
{
	char *message;
	size_t message_size;
	int len;
	int idx;
	int logfd;
};

static void Sys_AppendPrint( struct print_data *pd, const char *fmt, ... )
{
	va_list va;
	int len;

	va_start( va, fmt );
	len = Q_vsnprintf( pd->message, pd->message_size, fmt, va );
	va_end( va );

	if( len > 0 )
	{
		char ch = '\n';

		write( pd->logfd, pd->message, len );
		write( pd->logfd, &ch, 1 );

		write( STDERR_FILENO, pd->message, len );
		write( STDERR_FILENO, &ch, 1 );

		pd->message += len;
		pd->len += len;
		pd->message_size -= len;
	}
}

static void Sys_BacktracePrintError( void *data, const char *msg, int errnum )
{
	struct print_data *pd = data;
	Sys_AppendPrint( pd, "%2d: error: %s (%d)\n", pd->idx++, msg, errnum );
}

static void Sys_BacktracePrintSyminfo( void *data, uintptr_t pc, const char *symname, uintptr_t symval, uintptr_t symsize )
{
	struct print_data *pd = data;
	Dl_info dlinfo = { 0 };
	const char *module_name;

	if( dladdr((void *)pc, &dlinfo ))
		module_name = dlinfo.dli_fname;
	else module_name = NULL;

	if( symname )
	{
		if( module_name )
			Sys_AppendPrint( pd, "%2d: <%s+%d> (%s)\n", pd->idx++, symname, pc - symval, module_name );
		else
			Sys_AppendPrint( pd, "%2d: <%s+%d>\n", pd->idx++, symname, pc - symval );
	}
	else
	{
		if( module_name )
			Sys_AppendPrint( pd, "%2d: %p (%s)\n", pd->idx++, pc, module_name );
		else
			Sys_AppendPrint( pd, "%2d: %p\n", pd->idx++, pc );
	}
}

static int Sys_BacktracePrintFull( void *data, uintptr_t pc, const char *filename, int lineno, const char *function )
{
	struct print_data *pd = data;
	Dl_info dlinfo = { 0 };
	const char *module_name;

	if( dladdr((void *)pc, &dlinfo ))
		module_name = dlinfo.dli_fname;
	else module_name = NULL;

	if( filename && lineno >= 0 && function )
	{
		filename = COM_FileWithoutPath( filename );

		if( module_name )
			Sys_AppendPrint( pd, "%2d: %s (%s:%d) (%s)\n", pd->idx++, function, filename, lineno, module_name );
		else
			Sys_AppendPrint( pd, "%2d: %s (%s:%d)\n", pd->idx++, function, filename, lineno );
	}
	else
	{
		backtrace_syminfo( g_bt_state, pc, Sys_BacktracePrintSyminfo, Sys_BacktraceError, data );
	}

	return 0;
}

void Sys_CrashLibbacktrace( int signal, siginfo_t *si, void *context )
{
	char message[8192];
	int len, logfd;
	struct print_data pd = { .idx = 0 };

	(void)context;

	// flush buffers before writing directly to descriptors
	fflush( stdout );
	fflush( stderr );

	// safe actions first, stack and memory may be corrupted
	len = Q_snprintf( message, sizeof( message ), "Ver: " XASH_ENGINE_NAME " " XASH_VERSION " (build %i-%s-%s, %s-%s)\n",
					  Q_buildnum(), g_buildcommit, g_buildbranch, Q_buildos(), Q_buildarch() );

#if !XASH_FREEBSD && !XASH_NETBSD && !XASH_OPENBSD && !XASH_APPLE // they don't have si_ptr
	len += Q_snprintf( message + len, sizeof( message ) - len, "Crash: signal %d errno %d with code %d at %p %p\n", signal, si->si_errno, si->si_code, si->si_addr, si->si_ptr );
#else
	len += Q_snprintf( message + len, sizeof( message ) - len, "Crash: signal %d errno %d with code %d at %p\n", signal, si->si_errno, si->si_code, si->si_addr );
#endif

	write( STDERR_FILENO, message, len );

	// now get log fd and write trace directly to log
	pd.logfd = logfd = Sys_LogFileNo();
	write( logfd, message, len );

	pd.message = message + len;
	pd.message_size = sizeof( message ) - len;
	pd.len = 0;

	backtrace_full( g_bt_state, 1, Sys_BacktracePrintFull, Sys_BacktracePrintError, &pd );

	// put MessageBox as Sys_Error
	Msg( "%s\n", message );
#if !XASH_DEDICATED
	IN_SetMouseGrab( false );
#endif
	host.crashed = true;
	Platform_MessageBox( "Xash Error", message, false );

	// log saved, now we can try to save configs and close log correctly, it may crash
	if( host.type == HOST_NORMAL )
		CL_Crashed();
	host.status = HOST_CRASHED;

	Sys_Quit( "crashed" );
}

qboolean Sys_SetupLibbacktrace( const char *argv0 )
{
	enable_libbacktrace = true;
	g_bt_state = backtrace_create_state( argv0, true, Sys_BacktraceError, NULL );
	return g_bt_state != NULL && enable_libbacktrace;
}

#endif // HAVE_EXECINFO