/*
 *  linux/kernel/signal.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file README.legal in the main directory of this archive
 * for more details.
 */

/*
 * 680x0 support by Hamish Macdonald
 */

#include <asm/system.h>
#include <asm/segment.h>

#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/traps.h>
#include <linux/signal.h>
#include <linux/errno.h>
#include <linux/wait.h>
#include <linux/ptrace.h>
#include <linux/unistd.h>

#define _S(nr) (1<<((nr)-1))

#define _BLOCKABLE (~(_S(SIGKILL) | _S(SIGSTOP)))

asmlinkage int do_signal(unsigned long oldmask, struct frame * regs);

asmlinkage int sys_sigprocmask(int how, sigset_t *set, sigset_t *oset)
{
	sigset_t new_set, old_set = current->blocked;
	int error;

	if (set) {
		error = verify_area(VERIFY_READ, set, sizeof(sigset_t));
		if (error)
			return error;
		new_set = get_fs_long((unsigned long *) set) & _BLOCKABLE;
		switch (how) {
		case SIG_BLOCK:
			current->blocked |= new_set;
			break;
		case SIG_UNBLOCK:
			current->blocked &= ~new_set;
			break;
		case SIG_SETMASK:
			current->blocked = new_set;
			break;
		default:
			return -EINVAL;
		}
	}
	if (oset) {
		error = verify_area(VERIFY_WRITE, oset, sizeof(sigset_t));
		if (error)
			return error;
		put_fs_long(old_set, (unsigned long *) oset);
	}
	return 0;
}

asmlinkage int sys_sgetmask(void)
{
	return current->blocked;
}

asmlinkage int sys_ssetmask(int newmask)
{
	int old=current->blocked;

	current->blocked = newmask & _BLOCKABLE;
	return old;
}

asmlinkage int sys_sigpending(sigset_t *set)
{
	int error;
	/* fill in "set" with signals pending but blocked. */
	error = verify_area(VERIFY_WRITE, set, 4);
	if (!error)
		put_fs_long(current->blocked & current->signal, (unsigned long *)set);
	return error;
}

/*
 * atomically swap in the new signal mask, and wait for a signal.
 */
asmlinkage int sys_sigsuspend(int restart, unsigned long oldmask, unsigned long set)
{
	unsigned long mask;
	struct frame * regs = (struct frame *) &restart;

	mask = current->blocked;
	current->blocked = set & _BLOCKABLE;
	regs->d0 = -EINTR;
	while (1) {
		current->state = TASK_INTERRUPTIBLE;
		schedule();
		if (do_signal(mask,regs))
			return -EINTR;
	}
}

/*
 * POSIX 3.3.1.3:
 *  "Setting a signal action to SIG_IGN for a signal that is pending
 *   shall cause the pending signal to be discarded, whether or not
 *   it is blocked" (but SIGCHLD is unspecified: linux leaves it alone).
 *
 *  "Setting a signal action to SIG_DFL for a signal that is pending
 *   and whose default action is to ignore the signal (for example,
 *   SIGCHLD), shall cause the pending signal to be discarded, whether
 *   or not it is blocked"
 *
 * Note the silly behaviour of SIGCHLD: SIG_IGN means that the signal
 * isn't actually ignored, but does automatic child reaping, while
 * SIG_DFL is explicitly said by POSIX to force the signal to be ignored..
 */
static void check_pending(int signum)
{
	struct sigaction *p;

	p = signum - 1 + current->sigaction;
	if (p->sa_handler == SIG_IGN) {
		if (signum == SIGCHLD)
			return;
		current->signal &= ~_S(signum);
		return;
	}
	if (p->sa_handler == SIG_DFL) {
		if (signum != SIGCONT && signum != SIGCHLD && signum != SIGWINCH)
			return;
		current->signal &= ~_S(signum);
		return;
	}
}

asmlinkage int sys_signal(int signum, unsigned long handler)
{
	struct sigaction tmp;

	if (signum<1 || signum>32 || signum==SIGKILL || signum==SIGSTOP)
		return -EINVAL;
	if (handler >= TASK_SIZE)
		return -EFAULT;
	tmp.sa_handler = (void (*)(int)) handler;
	tmp.sa_mask = 0;
	tmp.sa_flags = SA_ONESHOT | SA_NOMASK;
	tmp.sa_restorer = NULL;
	handler = (long) current->sigaction[signum-1].sa_handler;
	current->sigaction[signum-1] = tmp;
	check_pending(signum);
	return handler;
}

asmlinkage int sys_sigaction(int signum, const struct sigaction * action,
	struct sigaction * oldaction)
{
	struct sigaction new_sa, *p;

	if (signum<1 || signum>32 || signum==SIGKILL || signum==SIGSTOP)
		return -EINVAL;
	p = signum - 1 + current->sigaction;
	if (action) {
		memcpy_fromfs(&new_sa, action, sizeof(struct sigaction));
		if (new_sa.sa_flags & SA_NOMASK)
			new_sa.sa_mask = 0;
		else {
			new_sa.sa_mask |= _S(signum);
			new_sa.sa_mask &= _BLOCKABLE;
		}
		if (TASK_SIZE <= (unsigned long) new_sa.sa_handler)
			return -EFAULT;
	}
	if (oldaction) {
		if (!verify_area(VERIFY_WRITE,oldaction, sizeof(struct sigaction)))
			memcpy_tofs(oldaction, p, sizeof(struct sigaction));
	}
	if (action) {
		*p = new_sa;
		check_pending(signum);
	}
	return 0;
}