/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*
 * Copyright (c) 1983, 1984, 1985, 1986, 1987, 1988, 1989 AT&T
 * All Rights Reserved
 *
 * Portions of this source code were derived from Berkeley
 * 4.3 BSD under license from the regents of the University of
 * California.
 */

/* Swap handler for SIGFPE codes.	 */

#include "lint.h"
#include <mtlib.h>
#include <errno.h>
#include <signal.h>
#include <floatingpoint.h>
#include <sys/types.h>
#include <sys/ucontext.h>
#include <sys/siginfo.h>
#include <thread.h>
#include <synch.h>
#include <stdlib.h>

#ifndef FPE_INTDIV
#define	FPE_INTDIV	1 /* integer divide by zero */
#endif
#ifndef FPE_INTOVF
#define	FPE_INTOVF	2 /* integer overflow */
#endif
#ifndef FPE_FLTDIV
#define	FPE_FLTDIV	3 /* [floating divide by zero] */
#endif
#ifndef FPE_FLTOVF
#define	FPE_FLTOVF	4 /* [floating overflow] */
#endif
#ifndef FPE_FLTUND
#define	FPE_FLTUND	5 /* [floating underflow] */
#endif
#ifndef FPE_FLTRES
#define	FPE_FLTRES	6 /* [floating inexact result] */
#endif
#ifndef FPE_FLTINV
#define	FPE_FLTINV	7 /* [floating invalid operation] */
#endif

#if defined(__i386) || defined(__amd64)

#ifndef	FPE_FLTSUB
#define	FPE_FLTSUB	8 /* subscript out of range */
#endif
#ifndef	FPE_FLTDEN
#define	FPE_FLTDEN	9 /* x86-specific: denormal operand */
#endif

#define	N_SIGFPE_CODE	10

#else

#define	N_SIGFPE_CODE	8

#endif /* __i386 */

/* Array of SIGFPE codes. */

static const sigfpe_code_type sigfpe_codes[N_SIGFPE_CODE] = {
	FPE_INTDIV,
	FPE_INTOVF,
	FPE_FLTDIV,
	FPE_FLTOVF,
	FPE_FLTUND,
	FPE_FLTRES,
	FPE_FLTINV,
#if defined(__i386) || defined(__amd64)
	FPE_FLTSUB,
	FPE_FLTDEN,
#endif
	0
};

/* Array of handlers. */

static mutex_t sigfpe_lock = DEFAULTMUTEX;

sigfpe_handler_type ieee_handlers[N_IEEE_EXCEPTION];
static sigfpe_handler_type sigfpe_handlers[N_SIGFPE_CODE];

static	int	_sigfpe_master_enabled;
/* Originally zero, set to 1 by _enable_sigfpe_master. */

#ifndef BADSIG
#define	BADSIG		(void (*)(void))-1
#endif

static void
_sigfpe_master(int sig, siginfo_t *siginfo, void *arg)
{
	ucontext_t	*ucontext = arg;
	int		i;
	int		code;
	enum fp_exception_type exception;

	lmutex_lock(&sigfpe_lock);
	code = siginfo->si_code;
	for (i = 0; (i < N_SIGFPE_CODE) && (code != sigfpe_codes[i]); i++)
		continue;
	/* Find index of handler. */
	if (i >= N_SIGFPE_CODE)
		i = N_SIGFPE_CODE - 1;
	switch ((intptr_t)sigfpe_handlers[i]) {
	case ((intptr_t)(SIGFPE_DEFAULT)):
		switch (code) {
		case FPE_FLTINV:
			exception = fp_invalid;
			goto ieee;
		case FPE_FLTRES:
			exception = fp_inexact;
			goto ieee;
		case FPE_FLTDIV:
			exception = fp_division;
			goto ieee;
		case FPE_FLTUND:
			exception = fp_underflow;
			goto ieee;
		case FPE_FLTOVF:
			exception = fp_overflow;
			goto ieee;
#if defined(__i386) || defined(__amd64)
		case FPE_FLTDEN:
			exception = fp_denormalized;
			goto ieee;
#endif
		default:	/* The common default treatment is to abort. */
			break;
		}
		/* FALLTHROUGH */
	case ((intptr_t)(SIGFPE_ABORT)):
		abort();
		break;
	case ((intptr_t)(SIGFPE_IGNORE)):
		lmutex_unlock(&sigfpe_lock);
		return;
	default:	/* User-defined not SIGFPE_DEFAULT or SIGFPE_ABORT. */
		(sigfpe_handlers[i])(sig, siginfo, ucontext);
		lmutex_unlock(&sigfpe_lock);
		return;
	}
ieee:
	switch ((intptr_t)ieee_handlers[(int)exception]) {
	case ((intptr_t)(SIGFPE_DEFAULT)): /* Error condition but ignore it. */
	case ((intptr_t)(SIGFPE_IGNORE)): /* Error condition but ignore it. */
		lmutex_unlock(&sigfpe_lock);
		return;
	case ((intptr_t)(SIGFPE_ABORT)):
		abort();
	default:
		(ieee_handlers[(int)exception])(sig, siginfo, ucontext);
		lmutex_unlock(&sigfpe_lock);
		return;
	}
}

static int
_enable_sigfpe_master(void)
{
	/* Enable the sigfpe master handler always. */
	struct sigaction newsigact, oldsigact;

	newsigact.sa_sigaction = _sigfpe_master;
	(void) sigemptyset(&newsigact.sa_mask);
	newsigact.sa_flags = SA_SIGINFO;	/* enhanced handler */
	_sigfpe_master_enabled = 1;
	return (sigaction(SIGFPE, &newsigact, &oldsigact));
}

static int
_test_sigfpe_master(void)
{
	/*
	 * Enable the sigfpe master handler if it's never been enabled
	 * before.
	 */

	if (_sigfpe_master_enabled == 0)
		return (_enable_sigfpe_master());
	else
		return (_sigfpe_master_enabled);
}

sigfpe_handler_type
sigfpe(sigfpe_code_type code, sigfpe_handler_type hdl)
{
	sigfpe_handler_type oldhdl;
	int		i;

	lmutex_lock(&sigfpe_lock);
	(void) _test_sigfpe_master();
	for (i = 0; (i < N_SIGFPE_CODE) && (code != sigfpe_codes[i]); i++)
		continue;
	/* Find index of handler. */
	if (i >= N_SIGFPE_CODE) {
		errno = EINVAL;
		lmutex_unlock(&sigfpe_lock);
		/* Not 0 or SIGFPE code */
		return ((sigfpe_handler_type)BADSIG);
	}
	oldhdl = sigfpe_handlers[i];
	sigfpe_handlers[i] = hdl;
	lmutex_unlock(&sigfpe_lock);
	return (oldhdl);
}