text: /*
   * Copyright (c) 1982, 1986, 1989, 1991, 1993
   *	The Regents of the University of California.  All rights reserved.
   * (c) UNIX System Laboratories, Inc.
   * All or some portions of this file are derived from material licensed
   * to the University of California by American Telephone and Telegraph
   * Co. or Unix System Laboratories, Inc. and are reproduced herein with
   * the permission of UNIX System Laboratories, Inc.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in the
   *    documentation and/or other materials provided with the distribution.
   * 3. Neither the name of the University nor the names of its contributors
   *    may be used to endorse or promote products derived from this software
   *    without specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   * SUCH DAMAGE.
   *
   *	@(#)kern_sig.c	8.7 (Berkeley) 4/18/94
   * $FreeBSD: src/sys/kern/kern_sig.c,v 1.72.2.17 2003/05/16 16:34:34 obrien Exp $
   */
  
  #include "opt_ktrace.h"
  
  #include <sys/param.h>
  #include <sys/systm.h>
  #include <sys/kernel.h>
  #include <sys/sysproto.h>
  #include <sys/signalvar.h>
  #include <sys/resourcevar.h>
  #include <sys/vnode.h>
  #include <sys/event.h>
  #include <sys/proc.h>
  #include <sys/nlookup.h>
  #include <sys/pioctl.h>
  #include <sys/acct.h>
  #include <sys/fcntl.h>
  #include <sys/lock.h>
  #include <sys/wait.h>
  #include <sys/ktrace.h>
  #include <sys/syslog.h>
  #include <sys/stat.h>
  #include <sys/sysent.h>
  #include <sys/sysctl.h>
  #include <sys/malloc.h>
  #include <sys/interrupt.h>
  #include <sys/unistd.h>
  #include <sys/kern_syscall.h>
  #include <sys/vkernel.h>
  
  #include <sys/signal2.h>
  #include <sys/thread2.h>
  #include <sys/spinlock2.h>
  
  #include <machine/cpu.h>
  #include <machine/smp.h>
  
  static int	coredump(struct lwp *, int);
  static char	*expand_name(const char *, uid_t, pid_t);
  static int	dokillpg(int sig, int pgid, int all);
  static int	sig_ffs(sigset_t *set);
  static int	sigprop(int sig);
  static void	lwp_signotify(struct lwp *lp);
  static void	lwp_signotify_remote(void *arg);
  static int	kern_sigtimedwait(sigset_t set, siginfo_t *info,
  		    struct timespec *timeout);
  
  static int	filt_sigattach(struct knote *kn);
  static void	filt_sigdetach(struct knote *kn);
  static int	filt_signal(struct knote *kn, long hint);
  
  struct filterops sig_filtops =
  	{ 0, filt_sigattach, filt_sigdetach, filt_signal };
  
  static int	kern_logsigexit = 1;
  SYSCTL_INT(_kern, KERN_LOGSIGEXIT, logsigexit, CTLFLAG_RW, 
      &kern_logsigexit, 0, 
      "Log processes quitting on abnormal signals to syslog(3)");
  
  /*
   * Can process p, with pcred pc, send the signal sig to process q?
   */
  #define CANSIGNAL(q, sig) \
  	(!p_trespass(curproc->p_ucred, (q)->p_ucred) || \
  	((sig) == SIGCONT && (q)->p_session == curproc->p_session))
  
  /*
   * Policy -- Can real uid ruid with ucred uc send a signal to process q?
   */
  #define CANSIGIO(ruid, uc, q) \
  	((uc)->cr_uid == 0 || \
  	    (ruid) == (q)->p_ucred->cr_ruid || \
  	    (uc)->cr_uid == (q)->p_ucred->cr_ruid || \
  	    (ruid) == (q)->p_ucred->cr_uid || \
  	    (uc)->cr_uid == (q)->p_ucred->cr_uid)
  
  int sugid_coredump;
  SYSCTL_INT(_kern, OID_AUTO, sugid_coredump, CTLFLAG_RW, 
  	&sugid_coredump, 0, "Enable coredumping set user/group ID processes");
  
  static int	do_coredump = 1;
  SYSCTL_INT(_kern, OID_AUTO, coredump, CTLFLAG_RW,
  	&do_coredump, 0, "Enable/Disable coredumps");
  
  /*
   * Signal properties and actions.
   * The array below categorizes the signals and their default actions
   * according to the following properties:
   */
  #define	SA_KILL		0x01		/* terminates process by default */
  #define	SA_CORE		0x02		/* ditto and coredumps */
  #define	SA_STOP		0x04		/* suspend process */
  #define	SA_TTYSTOP	0x08		/* ditto, from tty */
  #define	SA_IGNORE	0x10		/* ignore by default */
  #define	SA_CONT		0x20		/* continue if suspended */
  #define	SA_CANTMASK	0x40		/* non-maskable, catchable */
  #define SA_CKPT         0x80            /* checkpoint process */
  
  
  static int sigproptbl[NSIG] = {
          SA_KILL,                /* SIGHUP */
          SA_KILL,                /* SIGINT */
          SA_KILL|SA_CORE,        /* SIGQUIT */
          SA_KILL|SA_CORE,        /* SIGILL */
          SA_KILL|SA_CORE,        /* SIGTRAP */
          SA_KILL|SA_CORE,        /* SIGABRT */
          SA_KILL|SA_CORE,        /* SIGEMT */
          SA_KILL|SA_CORE,        /* SIGFPE */
          SA_KILL,                /* SIGKILL */
          SA_KILL|SA_CORE,        /* SIGBUS */
          SA_KILL|SA_CORE,        /* SIGSEGV */
          SA_KILL|SA_CORE,        /* SIGSYS */
          SA_KILL,                /* SIGPIPE */
          SA_KILL,                /* SIGALRM */
          SA_KILL,                /* SIGTERM */
          SA_IGNORE,              /* SIGURG */
          SA_STOP,                /* SIGSTOP */
          SA_STOP|SA_TTYSTOP,     /* SIGTSTP */
          SA_IGNORE|SA_CONT,      /* SIGCONT */
          SA_IGNORE,              /* SIGCHLD */
          SA_STOP|SA_TTYSTOP,     /* SIGTTIN */
          SA_STOP|SA_TTYSTOP,     /* SIGTTOU */
          SA_IGNORE,              /* SIGIO */
          SA_KILL,                /* SIGXCPU */
          SA_KILL,                /* SIGXFSZ */
          SA_KILL,                /* SIGVTALRM */
          SA_KILL,                /* SIGPROF */
          SA_IGNORE,              /* SIGWINCH  */
          SA_IGNORE,              /* SIGINFO */
          SA_KILL,                /* SIGUSR1 */
          SA_KILL,                /* SIGUSR2 */
  	SA_IGNORE,              /* SIGTHR */
  	SA_CKPT,                /* SIGCKPT */ 
  	SA_KILL|SA_CKPT,        /* SIGCKPTEXIT */  
  	SA_IGNORE,
  	SA_IGNORE,
  	SA_IGNORE,
  	SA_IGNORE,
  	SA_IGNORE,
  	SA_IGNORE,
  	SA_IGNORE,
  	SA_IGNORE,
  	SA_IGNORE,
  	SA_IGNORE,
  	SA_IGNORE,
  	SA_IGNORE,
  	SA_IGNORE,
  	SA_IGNORE,
  	SA_IGNORE,
  	SA_IGNORE,
  	SA_IGNORE,
  	SA_IGNORE,
  	SA_IGNORE,
  	SA_IGNORE,
  	SA_IGNORE,
  	SA_IGNORE,
  	SA_IGNORE,
  	SA_IGNORE,
  	SA_IGNORE,
  	SA_IGNORE,
  	SA_IGNORE,
  	SA_IGNORE,
  	SA_IGNORE,
  	SA_IGNORE,
  
  };
  
  static __inline int
  sigprop(int sig)
  {
  
  	if (sig > 0 && sig < NSIG)
  		return (sigproptbl[_SIG_IDX(sig)]);
  	return (0);
  }
  
  static __inline int
  sig_ffs(sigset_t *set)
  {
  	int i;
  
  	for (i = 0; i < _SIG_WORDS; i++)
  		if (set->__bits[i])
  			return (ffs(set->__bits[i]) + (i * 32));
  	return (0);
  }
  
  /* 
   * No requirements. 
   */
  int
  kern_sigaction(int sig, struct sigaction *act, struct sigaction *oact)
  {
  	struct thread *td = curthread;
  	struct proc *p = td->td_proc;
  	struct lwp *lp;
  	struct sigacts *ps = p->p_sigacts;
  
  	if (sig <= 0 || sig > _SIG_MAXSIG)
  		return (EINVAL);
  
  	lwkt_gettoken(&p->p_token);
  
  	if (oact) {
  		oact->sa_handler = ps->ps_sigact[_SIG_IDX(sig)];
  		oact->sa_mask = ps->ps_catchmask[_SIG_IDX(sig)];
  		oact->sa_flags = 0;
  		if (SIGISMEMBER(ps->ps_sigonstack, sig))
  			oact->sa_flags |= SA_ONSTACK;
  		if (!SIGISMEMBER(ps->ps_sigintr, sig))
  			oact->sa_flags |= SA_RESTART;
  		if (SIGISMEMBER(ps->ps_sigreset, sig))
  			oact->sa_flags |= SA_RESETHAND;
  		if (SIGISMEMBER(ps->ps_signodefer, sig))
  			oact->sa_flags |= SA_NODEFER;
  		if (SIGISMEMBER(ps->ps_siginfo, sig))
  			oact->sa_flags |= SA_SIGINFO;
  		if (sig == SIGCHLD && p->p_sigacts->ps_flag & PS_NOCLDSTOP)
  			oact->sa_flags |= SA_NOCLDSTOP;
  		if (sig == SIGCHLD && p->p_sigacts->ps_flag & PS_NOCLDWAIT)
  			oact->sa_flags |= SA_NOCLDWAIT;
  	}
  	if (act) {
  		/*
  		 * Check for invalid requests.  KILL and STOP cannot be
  		 * caught.
  		 */
  		if (sig == SIGKILL || sig == SIGSTOP) {
  			if (act->sa_handler != SIG_DFL) {
  				lwkt_reltoken(&p->p_token);
  				return (EINVAL);
  			}
  		}
  
  		/*
  		 * Change setting atomically.
  		 */
  		ps->ps_catchmask[_SIG_IDX(sig)] = act->sa_mask;
  		SIG_CANTMASK(ps->ps_catchmask[_SIG_IDX(sig)]);
  		if (act->sa_flags & SA_SIGINFO) {
  			ps->ps_sigact[_SIG_IDX(sig)] =
  			    (__sighandler_t *)act->sa_sigaction;
  			SIGADDSET(ps->ps_siginfo, sig);
  		} else {
  			ps->ps_sigact[_SIG_IDX(sig)] = act->sa_handler;
  			SIGDELSET(ps->ps_siginfo, sig);
  		}
  		if (!(act->sa_flags & SA_RESTART))
  			SIGADDSET(ps->ps_sigintr, sig);
  		else
  			SIGDELSET(ps->ps_sigintr, sig);
  		if (act->sa_flags & SA_ONSTACK)
  			SIGADDSET(ps->ps_sigonstack, sig);
  		else
  			SIGDELSET(ps->ps_sigonstack, sig);
  		if (act->sa_flags & SA_RESETHAND)
  			SIGADDSET(ps->ps_sigreset, sig);
  		else
  			SIGDELSET(ps->ps_sigreset, sig);
  		if (act->sa_flags & SA_NODEFER)
  			SIGADDSET(ps->ps_signodefer, sig);
  		else
  			SIGDELSET(ps->ps_signodefer, sig);
  		if (sig == SIGCHLD) {
  			if (act->sa_flags & SA_NOCLDSTOP)
  				p->p_sigacts->ps_flag |= PS_NOCLDSTOP;
  			else
  				p->p_sigacts->ps_flag &= ~PS_NOCLDSTOP;
  			if (act->sa_flags & SA_NOCLDWAIT) {
  				/*
  				 * Paranoia: since SA_NOCLDWAIT is implemented
  				 * by reparenting the dying child to PID 1 (and
  				 * trust it to reap the zombie), PID 1 itself
  				 * is forbidden to set SA_NOCLDWAIT.
  				 */
  				if (p->p_pid == 1)
  					p->p_sigacts->ps_flag &= ~PS_NOCLDWAIT;
  				else
  					p->p_sigacts->ps_flag |= PS_NOCLDWAIT;
  			} else {
  				p->p_sigacts->ps_flag &= ~PS_NOCLDWAIT;
  			}
  			if (ps->ps_sigact[_SIG_IDX(SIGCHLD)] == SIG_IGN)
  				ps->ps_flag |= PS_CLDSIGIGN;
  			else
  				ps->ps_flag &= ~PS_CLDSIGIGN;
  		}
  		/*
  		 * Set bit in p_sigignore for signals that are set to SIG_IGN,
  		 * and for signals set to SIG_DFL where the default is to
  		 * ignore. However, don't put SIGCONT in p_sigignore, as we
  		 * have to restart the process.
  		 *
  		 * Also remove the signal from the process and lwp signal
  		 * list.
  		 */
  		if (ps->ps_sigact[_SIG_IDX(sig)] == SIG_IGN ||
  		    (sigprop(sig) & SA_IGNORE &&
  		     ps->ps_sigact[_SIG_IDX(sig)] == SIG_DFL)) {
  			SIGDELSET(p->p_siglist, sig);
  			FOREACH_LWP_IN_PROC(lp, p) {
  				spin_lock(&lp->lwp_spin);
  				SIGDELSET(lp->lwp_siglist, sig);
  				spin_unlock(&lp->lwp_spin);
  			}
  			if (sig != SIGCONT) {
  				/* easier in ksignal */
  				SIGADDSET(p->p_sigignore, sig);
  			}
  			SIGDELSET(p->p_sigcatch, sig);
  		} else {
  			SIGDELSET(p->p_sigignore, sig);
  			if (ps->ps_sigact[_SIG_IDX(sig)] == SIG_DFL)
  				SIGDELSET(p->p_sigcatch, sig);
  			else
  				SIGADDSET(p->p_sigcatch, sig);
  		}
  	}
  	lwkt_reltoken(&p->p_token);
  	return (0);
  }
  
  int
  sys_sigaction(struct sigaction_args *uap)
  {
  	struct sigaction act, oact;
  	struct sigaction *actp, *oactp;
  	int error;
  
  	actp = (uap->act != NULL) ? &act : NULL;
  	oactp = (uap->oact != NULL) ? &oact : NULL;
  	if (actp) {
  		error = copyin(uap->act, actp, sizeof(act));
  		if (error)
  			return (error);
  	}
  	error = kern_sigaction(uap->sig, actp, oactp);
  	if (oactp && !error) {
  		error = copyout(oactp, uap->oact, sizeof(oact));
  	}
  	return (error);
  }
  
  /*
   * Initialize signal state for process 0;
   * set to ignore signals that are ignored by default.
   */
  void
  siginit(struct proc *p)
  {
  	int i;
  
  	for (i = 1; i <= NSIG; i++)
  		if (sigprop(i) & SA_IGNORE && i != SIGCONT)
  			SIGADDSET(p->p_sigignore, i);
  }
  
  /*
   * Reset signals for an exec of the specified process.
   */
  void
  execsigs(struct proc *p)
  {
  	struct sigacts *ps = p->p_sigacts;
  	struct lwp *lp;
  	int sig;
  
  	lp = ONLY_LWP_IN_PROC(p);
  
  	/*
  	 * Reset caught signals.  Held signals remain held
  	 * through p_sigmask (unless they were caught,
  	 * and are now ignored by default).
  	 */
  	while (SIGNOTEMPTY(p->p_sigcatch)) {
  		sig = sig_ffs(&p->p_sigcatch);
  		SIGDELSET(p->p_sigcatch, sig);
  		if (sigprop(sig) & SA_IGNORE) {
  			if (sig != SIGCONT)
  				SIGADDSET(p->p_sigignore, sig);
  			SIGDELSET(p->p_siglist, sig);
  			/* don't need spinlock */
  			SIGDELSET(lp->lwp_siglist, sig);
  		}
  		ps->ps_sigact[_SIG_IDX(sig)] = SIG_DFL;
  	}
  
  	/*
  	 * Reset stack state to the user stack.
  	 * Clear set of signals caught on the signal stack.
  	 */
  	lp->lwp_sigstk.ss_flags = SS_DISABLE;
  	lp->lwp_sigstk.ss_size = 0;
  	lp->lwp_sigstk.ss_sp = NULL;
  	lp->lwp_flags &= ~LWP_ALTSTACK;
  	/*
  	 * Reset no zombies if child dies flag as Solaris does.
  	 */
  	p->p_sigacts->ps_flag &= ~(PS_NOCLDWAIT | PS_CLDSIGIGN);
  	if (ps->ps_sigact[_SIG_IDX(SIGCHLD)] == SIG_IGN)
  		ps->ps_sigact[_SIG_IDX(SIGCHLD)] = SIG_DFL;
  }
  
  /*
   * kern_sigprocmask() - MP SAFE ONLY IF p == curproc
   *
   *	Manipulate signal mask.  This routine is MP SAFE *ONLY* if
   *	p == curproc.
   */
  int
  kern_sigprocmask(int how, sigset_t *set, sigset_t *oset)
  {
  	struct thread *td = curthread;
  	struct lwp *lp = td->td_lwp;
  	struct proc *p = td->td_proc;
  	int error;
  
  	lwkt_gettoken(&p->p_token);
  
  	if (oset != NULL)
  		*oset = lp->lwp_sigmask;
  
  	error = 0;
  	if (set != NULL) {
  		switch (how) {
  		case SIG_BLOCK:
  			SIG_CANTMASK(*set);
  			SIGSETOR(lp->lwp_sigmask, *set);
  			break;
  		case SIG_UNBLOCK:
  			SIGSETNAND(lp->lwp_sigmask, *set);
  			break;
  		case SIG_SETMASK:
  			SIG_CANTMASK(*set);
  			lp->lwp_sigmask = *set;
  			break;
  		default:
  			error = EINVAL;
  			break;
  		}
  	}
  
  	lwkt_reltoken(&p->p_token);
  
  	return (error);
  }
  
  /*
   * sigprocmask()
   *
   * MPSAFE
   */
  int
  sys_sigprocmask(struct sigprocmask_args *uap)
  {
  	sigset_t set, oset;
  	sigset_t *setp, *osetp;
  	int error;
  
  	setp = (uap->set != NULL) ? &set : NULL;
  	osetp = (uap->oset != NULL) ? &oset : NULL;
  	if (setp) {
  		error = copyin(uap->set, setp, sizeof(set));
  		if (error)
  			return (error);
  	}
  	error = kern_sigprocmask(uap->how, setp, osetp);
  	if (osetp && !error) {
  		error = copyout(osetp, uap->oset, sizeof(oset));
  	}
  	return (error);
  }
  
  /*
   * MPSAFE
   */
  int
  kern_sigpending(struct __sigset *set)
  {
  	struct lwp *lp = curthread->td_lwp;
  
  	*set = lwp_sigpend(lp);
  
  	return (0);
  }
  
  /*
   * MPSAFE
   */
  int
  sys_sigpending(struct sigpending_args *uap)
  {
  	sigset_t set;
  	int error;
  
  	error = kern_sigpending(&set);
  
  	if (error == 0)
  		error = copyout(&set, uap->set, sizeof(set));
  	return (error);
  }
  
  /*
   * Suspend process until signal, providing mask to be set
   * in the meantime.
   *
   * MPSAFE
   */
  int
  kern_sigsuspend(struct __sigset *set)
  {
  	struct thread *td = curthread;
  	struct lwp *lp = td->td_lwp;
  	struct proc *p = td->td_proc;
  	struct sigacts *ps = p->p_sigacts;
  
  	/*
  	 * When returning from sigsuspend, we want
  	 * the old mask to be restored after the
  	 * signal handler has finished.  Thus, we
  	 * save it here and mark the sigacts structure
  	 * to indicate this.
  	 */
  	lp->lwp_oldsigmask = lp->lwp_sigmask;
  	lp->lwp_flags |= LWP_OLDMASK;
  
  	SIG_CANTMASK(*set);
  	lp->lwp_sigmask = *set;
  	while (tsleep(ps, PCATCH, "pause", 0) == 0)
  		/* void */;
  	/* always return EINTR rather than ERESTART... */
  	return (EINTR);
  }
  
  /*
   * Note nonstandard calling convention: libc stub passes mask, not
   * pointer, to save a copyin.
   *
   * MPSAFE
   */
  int
  sys_sigsuspend(struct sigsuspend_args *uap)
  {
  	sigset_t mask;
  	int error;
  
  	error = copyin(uap->sigmask, &mask, sizeof(mask));
  	if (error)
  		return (error);
  
  	error = kern_sigsuspend(&mask);
  
  	return (error);
  }
  
  /*
   * MPSAFE
   */
  int
  kern_sigaltstack(struct sigaltstack *ss, struct sigaltstack *oss)
  {
  	struct thread *td = curthread;
  	struct lwp *lp = td->td_lwp;
  	struct proc *p = td->td_proc;
  
  	if ((lp->lwp_flags & LWP_ALTSTACK) == 0)
  		lp->lwp_sigstk.ss_flags |= SS_DISABLE;
  
  	if (oss)
  		*oss = lp->lwp_sigstk;
  
  	if (ss) {
  		if (ss->ss_flags & ~SS_DISABLE)
  			return (EINVAL);
  		if (ss->ss_flags & SS_DISABLE) {
  			if (lp->lwp_sigstk.ss_flags & SS_ONSTACK)
  				return (EINVAL);
  			lp->lwp_flags &= ~LWP_ALTSTACK;
  			lp->lwp_sigstk.ss_flags = ss->ss_flags;
  		} else {
  			if (ss->ss_size < p->p_sysent->sv_minsigstksz)
  				return (ENOMEM);
  			lp->lwp_flags |= LWP_ALTSTACK;
  			lp->lwp_sigstk = *ss;
  		}
  	}
  
  	return (0);
  }
  
  /*
   * MPSAFE
   */
  int
  sys_sigaltstack(struct sigaltstack_args *uap)
  {
  	stack_t ss, oss;
  	int error;
  
  	if (uap->ss) {
  		error = copyin(uap->ss, &ss, sizeof(ss));
  		if (error)
  			return (error);
  	}
  
  	error = kern_sigaltstack(uap->ss ? &ss : NULL,
  	    uap->oss ? &oss : NULL);
  
  	if (error == 0 && uap->oss)
  		error = copyout(&oss, uap->oss, sizeof(*uap->oss));
  	return (error);
  }
  
  /*
   * Common code for kill process group/broadcast kill.
   * cp is calling process.
   */
  struct killpg_info {
  	int nfound;
  	int sig;
  };
  
  static int killpg_all_callback(struct proc *p, void *data);
  
  static int
  dokillpg(int sig, int pgid, int all)
  {
  	struct killpg_info info;
  	struct proc *cp = curproc;
  	struct proc *p;
  	struct pgrp *pgrp;
  
  	info.nfound = 0;
  	info.sig = sig;
  
  	if (all) {
  		/*
  		 * broadcast
  		 */
  		allproc_scan(killpg_all_callback, &info);
  	} else {
  		if (pgid == 0) {
  			/*
  			 * zero pgid means send to my process group.
  			 */
  			pgrp = cp->p_pgrp;
  			pgref(pgrp);
  		} else {
  			pgrp = pgfind(pgid);
  			if (pgrp == NULL)
  				return (ESRCH);
  		}
  
  		/*
  		 * Must interlock all signals against fork
  		 */
  		lockmgr(&pgrp->pg_lock, LK_EXCLUSIVE);
  		LIST_FOREACH(p, &pgrp->pg_members, p_pglist) {
  			if (p->p_pid <= 1 || 
  			    p->p_stat == SZOMB ||
  			    (p->p_flags & P_SYSTEM) ||
  			    !CANSIGNAL(p, sig)) {
  				continue;
  			}
  			++info.nfound;
  			if (sig)
  				ksignal(p, sig);
  		}
  		lockmgr(&pgrp->pg_lock, LK_RELEASE);
  		pgrel(pgrp);
  	}
  	return (info.nfound ? 0 : ESRCH);
  }
  
  static int
  killpg_all_callback(struct proc *p, void *data)
  {
  	struct killpg_info *info = data;
  
  	if (p->p_pid <= 1 || (p->p_flags & P_SYSTEM) ||
  	    p == curproc || !CANSIGNAL(p, info->sig)) {
  		return (0);
  	}
  	++info->nfound;
  	if (info->sig)
  		ksignal(p, info->sig);
  	return(0);
  }
  
  /*
   * Send a general signal to a process or LWPs within that process.
   *
   * Note that new signals cannot be sent if a process is exiting or already
   * a zombie, but we return success anyway as userland is likely to not handle
   * the race properly.
   * 
   * No requirements.
   */
  int
  kern_kill(int sig, pid_t pid, lwpid_t tid)
  {
  	int t;
  
  	if ((u_int)sig > _SIG_MAXSIG)
  		return (EINVAL);
  
  	lwkt_gettoken(&proc_token);
  
  	if (pid > 0) {
  		struct proc *p;
  		struct lwp *lp = NULL;
  
  		/*
  		 * Send a signal to a single process.  If the kill() is
  		 * racing an exiting process which has not yet been reaped
  		 * act as though the signal was delivered successfully but
  		 * don't actually try to deliver the signal.
  		 */
  		if ((p = pfind(pid)) == NULL) {
  			if ((p = zpfind(pid)) == NULL) {
  				lwkt_reltoken(&proc_token);
  				return (ESRCH);
  			}
  			lwkt_reltoken(&proc_token);
  			PRELE(p);
  			return (0);
  		}
  		lwkt_gettoken(&p->p_token);
  		if (!CANSIGNAL(p, sig)) {
  			lwkt_reltoken(&p->p_token);
  			PRELE(p);
  			lwkt_reltoken(&proc_token);
  			return (EPERM);
  		}
  
  		/*
  		 * NOP if the process is exiting.  Note that lwpsignal() is
  		 * called directly with P_WEXIT set to kill individual LWPs
  		 * during exit, which is allowed.
  		 */
  		if (p->p_flags & P_WEXIT) {
  			lwkt_reltoken(&p->p_token);
  			PRELE(p);
  			lwkt_reltoken(&proc_token);
  			return (0);
  		}
  		if (tid != -1) {
  			lp = lwp_rb_tree_RB_LOOKUP(&p->p_lwp_tree, tid);
  			if (lp == NULL) {
  				lwkt_reltoken(&p->p_token);
  				PRELE(p);
  				lwkt_reltoken(&proc_token);
  				return (ESRCH);
  			}
  		}
  		if (sig)
  			lwpsignal(p, lp, sig);
  		lwkt_reltoken(&p->p_token);
  		PRELE(p);
  		lwkt_reltoken(&proc_token);
  		return (0);
  	}
  
  	/*
  	 * If we come here, pid is a special broadcast pid.
  	 * This doesn't mix with a tid.
  	 */
  	if (tid != -1) {
  		lwkt_reltoken(&proc_token);
  		return (EINVAL);
  	}
  	switch (pid) {
  	case -1:		/* broadcast signal */
  		t = (dokillpg(sig, 0, 1));
  		break;
  	case 0:			/* signal own process group */
  		t = (dokillpg(sig, 0, 0));
  		break;
  	default:		/* negative explicit process group */
  		t = (dokillpg(sig, -pid, 0));
  		break;
  	}
  	lwkt_reltoken(&proc_token);
  	return t;
  }
  
  int
  sys_kill(struct kill_args *uap)
  {
  	int error;
  
  	error = kern_kill(uap->signum, uap->pid, -1);
  	return (error);
  }
  
  int
  sys_lwp_kill(struct lwp_kill_args *uap)
  {
  	int error;
  	pid_t pid = uap->pid;
  
  	/*
  	 * A tid is mandatory for lwp_kill(), otherwise
  	 * you could simply use kill().
  	 */
  	if (uap->tid == -1)
  		return (EINVAL);
  
  	/*
  	 * To save on a getpid() function call for intra-process
  	 * signals, pid == -1 means current process.
  	 */
  	if (pid == -1)
  		pid = curproc->p_pid;
  
  	error = kern_kill(uap->signum, pid, uap->tid);
  	return (error);
  }
  
  /*
   * Send a signal to a process group.
   */
  void
  gsignal(int pgid, int sig)
  {
  	struct pgrp *pgrp;
  
  	if (pgid && (pgrp = pgfind(pgid)))
  		pgsignal(pgrp, sig, 0);
  }
  
  /*
   * Send a signal to a process group.  If checktty is 1,
   * limit to members which have a controlling terminal.
   *
   * pg_lock interlocks against a fork that might be in progress, to
   * ensure that the new child process picks up the signal.
   */
  void
  pgsignal(struct pgrp *pgrp, int sig, int checkctty)
  {
  	struct proc *p;
  
  	/*
  	 * Must interlock all signals against fork
  	 */
  	if (pgrp) {
  		pgref(pgrp);
  		lockmgr(&pgrp->pg_lock, LK_EXCLUSIVE);
  		LIST_FOREACH(p, &pgrp->pg_members, p_pglist) {
  			if (checkctty == 0 || p->p_flags & P_CONTROLT)
  				ksignal(p, sig);
  		}
  		lockmgr(&pgrp->pg_lock, LK_RELEASE);
  		pgrel(pgrp);
  	}
  }
  
  /*
   * Send a signal caused by a trap to the current lwp.  If it will be caught
   * immediately, deliver it with correct code.  Otherwise, post it normally.
   *
   * These signals may ONLY be delivered to the specified lwp and may never
   * be delivered to the process generically.
   */
  void
  trapsignal(struct lwp *lp, int sig, u_long code)
  {
  	struct proc *p = lp->lwp_proc;
  	struct sigacts *ps = p->p_sigacts;
  
  	/*
  	 * If we are a virtual kernel running an emulated user process
  	 * context, switch back to the virtual kernel context before
  	 * trying to post the signal.
  	 */
  	if (lp->lwp_vkernel && lp->lwp_vkernel->ve) {
  		struct trapframe *tf = lp->lwp_md.md_regs;
  		tf->tf_trapno = 0;
  		vkernel_trap(lp, tf);
  	}
  
  
  	if ((p->p_flags & P_TRACED) == 0 && SIGISMEMBER(p->p_sigcatch, sig) &&
  	    !SIGISMEMBER(lp->lwp_sigmask, sig)) {
  		lp->lwp_ru.ru_nsignals++;
  #ifdef KTRACE
  		if (KTRPOINT(lp->lwp_thread, KTR_PSIG))
  			ktrpsig(lp, sig, ps->ps_sigact[_SIG_IDX(sig)],
  				&lp->lwp_sigmask, code);
  #endif
  		(*p->p_sysent->sv_sendsig)(ps->ps_sigact[_SIG_IDX(sig)], sig,
  						&lp->lwp_sigmask, code);
  		SIGSETOR(lp->lwp_sigmask, ps->ps_catchmask[_SIG_IDX(sig)]);
  		if (!SIGISMEMBER(ps->ps_signodefer, sig))
  			SIGADDSET(lp->lwp_sigmask, sig);
  		if (SIGISMEMBER(ps->ps_sigreset, sig)) {
  			/*
  			 * See kern_sigaction() for origin of this code.
  			 */
  			SIGDELSET(p->p_sigcatch, sig);
  			if (sig != SIGCONT &&
  			    sigprop(sig) & SA_IGNORE)
  				SIGADDSET(p->p_sigignore, sig);
  			ps->ps_sigact[_SIG_IDX(sig)] = SIG_DFL;
  		}
  	} else {
  		lp->lwp_code = code;	/* XXX for core dump/debugger */
  		lp->lwp_sig = sig;	/* XXX to verify code */
  		lwpsignal(p, lp, sig);
  	}
  }
  
  /*
   * Find a suitable lwp to deliver the signal to.  Returns NULL if all
   * lwps hold the signal blocked.
   *
   * Caller must hold p->p_token.
   *
   * Returns a lp or NULL.  If non-NULL the lp is held and its token is
   * acquired.
   */
  static struct lwp *
  find_lwp_for_signal(struct proc *p, int sig)
  {
  	struct lwp *lp;
  	struct lwp *run, *sleep, *stop;
  
  	/*
  	 * If the running/preempted thread belongs to the proc to which
  	 * the signal is being delivered and this thread does not block
  	 * the signal, then we can avoid a context switch by delivering
  	 * the signal to this thread, because it will return to userland
  	 * soon anyways.
  	 */
  	lp = lwkt_preempted_proc();
  	if (lp != NULL && lp->lwp_proc == p) {
  		LWPHOLD(lp);
  		lwkt_gettoken(&lp->lwp_token);
  		if (!SIGISMEMBER(lp->lwp_sigmask, sig)) {
  			/* return w/ token held */
  			return (lp);
  		}
  		lwkt_reltoken(&lp->lwp_token);
  		LWPRELE(lp);
  	}
  
  	run = sleep = stop = NULL;
  	FOREACH_LWP_IN_PROC(lp, p) {
  		/*
  		 * If the signal is being blocked by the lwp, then this
  		 * lwp is not eligible for receiving the signal.
  		 */
  		LWPHOLD(lp);
  		lwkt_gettoken(&lp->lwp_token);
  
  		if (SIGISMEMBER(lp->lwp_sigmask, sig)) {
  			lwkt_reltoken(&lp->lwp_token);
  			LWPRELE(lp);
  			continue;
  		}
  
  		switch (lp->lwp_stat) {
  		case LSRUN:
  			if (sleep) {
  				lwkt_token_swap();
  				lwkt_reltoken(&sleep->lwp_token);
  				LWPRELE(sleep);
  				sleep = NULL;
  				run = lp;
  			} else if (stop) {
  				lwkt_token_swap();
  				lwkt_reltoken(&stop->lwp_token);
  				LWPRELE(stop);
  				stop = NULL;
  				run = lp;
  			} else {
  				run = lp;
  			}
  			break;
  		case LSSLEEP:
  			if (lp->lwp_flags & LWP_SINTR) {
  				if (sleep) {
  					lwkt_reltoken(&lp->lwp_token);
  					LWPRELE(lp);
  				} else if (stop) {
  					lwkt_token_swap();
  					lwkt_reltoken(&stop->lwp_token);
  					LWPRELE(stop);
  					stop = NULL;
  					sleep = lp;
  				} else {
  					sleep = lp;
  				}
  			} else {
  				lwkt_reltoken(&lp->lwp_token);
  				LWPRELE(lp);
  			}
  			break;
  		case LSSTOP:
  			if (sleep) {
  				lwkt_reltoken(&lp->lwp_token);
  				LWPRELE(lp);
  			} else if (stop) {
  				lwkt_reltoken(&lp->lwp_token);
  				LWPRELE(lp);
  			} else {
  				stop = lp;
  			}
  			break;
  		}
  		if (run)
  			break;
  	}
  
  	if (run != NULL)
  		return (run);
  	else if (sleep != NULL)
  		return (sleep);
  	else
  		return (stop);
  }
  
  /*
   * Send the signal to the process.  If the signal has an action, the action
   * is usually performed by the target process rather than the caller; we add
   * the signal to the set of pending signals for the process.
   *
   * Exceptions:
   *   o When a stop signal is sent to a sleeping process that takes the
   *     default action, the process is stopped without awakening it.
   *   o SIGCONT restarts stopped processes (or puts them back to sleep)
   *     regardless of the signal action (eg, blocked or ignored).
   *
   * Other ignored signals are discarded immediately.
   *
   * If the caller wishes to call this function from a hard code section the
   * caller must already hold p->p_token (see kern_clock.c).
   *
   * No requirements.
   */
  void
  ksignal(struct proc *p, int sig)
  {
  	lwpsignal(p, NULL, sig);
  }
  
  /*
   * The core for ksignal.  lp may be NULL, then a suitable thread
   * will be chosen.  If not, lp MUST be a member of p.
   *
   * If the caller wishes to call this function from a hard code section the
   * caller must already hold p->p_token.
   *
   * No requirements.
   */
  void
  lwpsignal(struct proc *p, struct lwp *lp, int sig)
  {
  	struct proc *q;
  	sig_t action;
  	int prop;
  
  	if (sig > _SIG_MAXSIG || sig <= 0) {
  		kprintf("lwpsignal: signal %d\n", sig);
  		panic("lwpsignal signal number");
  	}
  
  	KKASSERT(lp == NULL || lp->lwp_proc == p);
  
  	/*
  	 * We don't want to race... well, all sorts of things.  Get appropriate
  	 * tokens.
  	 *
  	 * Don't try to deliver a generic signal to an exiting process,
  	 * the signal structures could be in flux.  We check the LWP later
  	 * on.
  	 */
  	PHOLD(p);
  	lwkt_gettoken(&p->p_token);
  	if (lp) {
  		LWPHOLD(lp);
  		lwkt_gettoken(&lp->lwp_token);
  	} else if (p->p_flags & P_WEXIT) {
  		goto out;
  	}
  
  	prop = sigprop(sig);
  
  	/*
  	 * If proc is traced, always give parent a chance;
  	 * if signal event is tracked by procfs, give *that*
  	 * a chance, as well.
  	 */
  	if ((p->p_flags & P_TRACED) || (p->p_stops & S_SIG)) {
  		action = SIG_DFL;
  	} else {
  		/*
  		 * Do not try to deliver signals to an exiting lwp.  Note
  		 * that we must still deliver the signal if P_WEXIT is set
  		 * in the process flags.
  		 */
  		if (lp && (lp->lwp_mpflags & LWP_MP_WEXIT)) {
  			if (lp) {
  				lwkt_reltoken(&lp->lwp_token);
  				LWPRELE(lp);
  			}
  			lwkt_reltoken(&p->p_token);
  			PRELE(p);
  			return;
  		}
  
  		/*
  		 * If the signal is being ignored, then we forget about
  		 * it immediately.  NOTE: We don't set SIGCONT in p_sigignore,
  		 * and if it is set to SIG_IGN, action will be SIG_DFL here.
  		 */
  		if (SIGISMEMBER(p->p_sigignore, sig)) {
  			/*
  			 * Even if a signal is set SIG_IGN, it may still be
  			 * lurking in a kqueue.
  			 */
  			KNOTE(&p->p_klist, NOTE_SIGNAL | sig);
  			if (lp) {
  				lwkt_reltoken(&lp->lwp_token);
  				LWPRELE(lp);
  			}
  			lwkt_reltoken(&p->p_token);
  			PRELE(p);
  			return;
  		}
  		if (SIGISMEMBER(p->p_sigcatch, sig))
  			action = SIG_CATCH;
  		else
  			action = SIG_DFL;
  	}
  
  	/*
  	 * If continuing, clear any pending STOP signals.
  	 */
  	if (prop & SA_CONT)
  		SIG_STOPSIGMASK(p->p_siglist);
  	
  	if (prop & SA_STOP) {
  		/*
  		 * If sending a tty stop signal to a member of an orphaned
  		 * process group, discard the signal here if the action
  		 * is default; don't stop the process below if sleeping,
  		 * and don't clear any pending SIGCONT.
  		 */
  		if (prop & SA_TTYSTOP && p->p_pgrp->pg_jobc == 0 &&
  		    action == SIG_DFL) {
  			if (lp) {
  				lwkt_reltoken(&lp->lwp_token);
  				LWPRELE(lp);
  			}
  			lwkt_reltoken(&p->p_token);
  			PRELE(p);
  		        return;
  		}
  		SIG_CONTSIGMASK(p->p_siglist);
  		p->p_flags &= ~P_CONTINUED;
  	}
  
  	if (p->p_stat == SSTOP) {
  		/*
  		 * Nobody can handle this signal, add it to the lwp or
  		 * process pending list 
  		 */
  		if (lp) {
  			spin_lock(&lp->lwp_spin);
  			SIGADDSET(lp->lwp_siglist, sig);
  			spin_unlock(&lp->lwp_spin);
  		} else {
  			SIGADDSET(p->p_siglist, sig);
  		}
  
  		/*
  		 * If the process is stopped and is being traced, then no
  		 * further action is necessary.
  		 */
  		if (p->p_flags & P_TRACED)
  			goto out;
  
  		/*
  		 * If the process is stopped and receives a KILL signal,
  		 * make the process runnable.
  		 */
  		if (sig == SIGKILL) {
  			proc_unstop(p);
  			goto active_process;
  		}
  
  		/*
  		 * If the process is stopped and receives a CONT signal,
  		 * then try to make the process runnable again.
  		 */
  		if (prop & SA_CONT) {
  			/*
  			 * If SIGCONT is default (or ignored), we continue the
  			 * process but don't leave the signal in p_siglist, as
  			 * it has no further action.  If SIGCONT is held, we
  			 * continue the process and leave the signal in
  			 * p_siglist.  If the process catches SIGCONT, let it
  			 * handle the signal itself.
  			 *
  			 * XXX what if the signal is being held blocked?
  			 *
  			 * Token required to interlock kern_wait().
  			 * Reparenting can also cause a race so we have to
  			 * hold (q).
  			 */
  			q = p->p_pptr;
  			PHOLD(q);
  			lwkt_gettoken(&q->p_token);
  			p->p_flags |= P_CONTINUED;
  			wakeup(q);
  			if (action == SIG_DFL)
  				SIGDELSET(p->p_siglist, sig);
  			proc_unstop(p);
  			lwkt_reltoken(&q->p_token);
  			PRELE(q);
  			if (action == SIG_CATCH)
  				goto active_process;
  			goto out;
  		}
  
  		/*
  		 * If the process is stopped and receives another STOP
  		 * signal, we do not need to stop it again.  If we did
  		 * the shell could get confused.
  		 *
  		 * However, if the current/preempted lwp is part of the
  		 * process receiving the signal, we need to keep it,
  		 * so that this lwp can stop in issignal() later, as
  		 * we don't want to wait until it reaches userret!
  		 */
  		if (prop & SA_STOP) {
  			if (lwkt_preempted_proc() == NULL ||
  			    lwkt_preempted_proc()->lwp_proc != p)
  				SIGDELSET(p->p_siglist, sig);
  		}
  
  		/*
  		 * Otherwise the process is stopped and it received some
  		 * signal, which does not change its stopped state.  When
  		 * the process is continued a wakeup(p) will be issued which
  		 * will wakeup any threads sleeping in tstop().
  		 */
  		if (lp == NULL) {
  			/* NOTE: returns lp w/ token held */
  			lp = find_lwp_for_signal(p, sig);
  		}
  		goto out;
  
  		/* NOTREACHED */
  	}
  	/* else not stopped */
  active_process:
  
  	/*
  	 * Never deliver a lwp-specific signal to a random lwp.
  	 */
  	if (lp == NULL) {
  		/* NOTE: returns lp w/ token held */
  		lp = find_lwp_for_signal(p, sig);
  		if (lp) {
  			if (SIGISMEMBER(lp->lwp_sigmask, sig)) {
  				lwkt_reltoken(&lp->lwp_token);
  				LWPRELE(lp);
  				lp = NULL;
  			}
  		}
  	}
  
  	/*
  	 * Deliver to the process generically if (1) the signal is being
  	 * sent to any thread or (2) we could not find a thread to deliver
  	 * it to.
  	 */
  	if (lp == NULL) {
  		SIGADDSET(p->p_siglist, sig);
  		goto out;
  	}
  
  	/*
  	 * Deliver to a specific LWP whether it masks it or not.  It will
  	 * not be dispatched if masked but we must still deliver it.
  	 */
  	if (p->p_nice > NZERO && action == SIG_DFL && (prop & SA_KILL) &&
  	    (p->p_flags & P_TRACED) == 0) {
  		p->p_nice = NZERO;
  	}
  
  	/*
  	 * If the process receives a STOP signal which indeed needs to
  	 * stop the process, do so.  If the process chose to catch the
  	 * signal, it will be treated like any other signal.
  	 */
  	if ((prop & SA_STOP) && action == SIG_DFL) {
  		/*
  		 * If a child holding parent blocked, stopping
  		 * could cause deadlock.  Take no action at this
  		 * time.
  		 */
  		if (p->p_flags & P_PPWAIT) {
  			SIGADDSET(p->p_siglist, sig);
  			goto out;
  		}
  
  		/*
  		 * Do not actually try to manipulate the process, but simply
  		 * stop it.  Lwps will stop as soon as they safely can.
  		 *
  		 * Ignore stop if the process is exiting.
  		 */
  		if ((p->p_flags & P_WEXIT) == 0) {
  			p->p_xstat = sig;
  			proc_stop(p);
  		}
  		goto out;
  	}
  
  	/*
  	 * If it is a CONT signal with default action, just ignore it.
  	 */
  	if ((prop & SA_CONT) && action == SIG_DFL)
  		goto out;
  
  	/*
  	 * Mark signal pending at this specific thread.
  	 */
  	spin_lock(&lp->lwp_spin);
  	SIGADDSET(lp->lwp_siglist, sig);
  	spin_unlock(&lp->lwp_spin);
  
  	lwp_signotify(lp);
  
  out:
  	if (lp) {
  		lwkt_reltoken(&lp->lwp_token);
  		LWPRELE(lp);
  	}
  	lwkt_reltoken(&p->p_token);
  	PRELE(p);
  }
  
  /*
   * Notify the LWP that a signal has arrived.  The LWP does not have to be
   * sleeping on the current cpu.
   *
   * p->p_token and lp->lwp_token must be held on call.
   *
   * We can only safely schedule the thread on its current cpu and only if
   * one of the SINTR flags is set.  If an SINTR flag is set AND we are on
   * the correct cpu we are properly interlocked, otherwise we could be
   * racing other thread transition states (or the lwp is on the user scheduler
   * runq but not scheduled) and must not do anything.
   *
   * Since we hold the lwp token we know the lwp cannot be ripped out from
   * under us so we can safely hold it to prevent it from being ripped out
   * from under us if we are forced to IPI another cpu to make the local
   * checks there.
   *
   * Adjustment of lp->lwp_stat can only occur when we hold the lwp_token,
   * which we won't in an IPI so any fixups have to be done here, effectively
   * replicating part of what setrunnable() does.
   */
  static void
  lwp_signotify(struct lwp *lp)
  {
  	ASSERT_LWKT_TOKEN_HELD(&lp->lwp_proc->p_token);
  
  	crit_enter();
  	if (lp == lwkt_preempted_proc()) {
  		/*
  		 * lwp is on the current cpu AND it is currently running
  		 * (we preempted it).
  		 */
  		signotify();
  	} else if (lp->lwp_flags & LWP_SINTR) {
  		/*
  		 * lwp is sitting in tsleep() with PCATCH set
  		 */
  		if (lp->lwp_thread->td_gd == mycpu) {
  			setrunnable(lp);
  		} else {
  			/*
  			 * We can only adjust lwp_stat while we hold the
  			 * lwp_token, and we won't in the IPI function.
  			 */
  			LWPHOLD(lp);
  			if (lp->lwp_stat == LSSTOP)
  				lp->lwp_stat = LSSLEEP;
  			lwkt_send_ipiq(lp->lwp_thread->td_gd,
  				       lwp_signotify_remote, lp);
  		}
  	} else if (lp->lwp_thread->td_flags & TDF_SINTR) {
  		/*
  		 * lwp is sitting in lwkt_sleep() with PCATCH set.
  		 */
  		if (lp->lwp_thread->td_gd == mycpu) {
  			setrunnable(lp);
  		} else {
  			/*
  			 * We can only adjust lwp_stat while we hold the
  			 * lwp_token, and we won't in the IPI function.
  			 */
  			LWPHOLD(lp);
  			if (lp->lwp_stat == LSSTOP)
  				lp->lwp_stat = LSSLEEP;
  			lwkt_send_ipiq(lp->lwp_thread->td_gd,
  				       lwp_signotify_remote, lp);
  		}
  	} else {
  		/*
  		 * Otherwise the lwp is either in some uninterruptable state
  		 * or it is on the userland scheduler's runqueue waiting to
  		 * be scheduled to a cpu.
  		 */
  	}
  	crit_exit();
  }
  
  /*
   * This function is called via an IPI so we cannot call setrunnable() here
   * (because while we hold the lp we don't own its token, and can't get it
   * from an IPI).
   *
   * We are interlocked by virtue of being on the same cpu as the target.  If
   * we still are and LWP_SINTR or TDF_SINTR is set we can safely schedule
   * the target thread.
   */
  static void
  lwp_signotify_remote(void *arg)
  {
  	struct lwp *lp = arg;
  	thread_t td = lp->lwp_thread;
  
  	if (lp == lwkt_preempted_proc()) {
  		signotify();
  		LWPRELE(lp);
  	} else if (td->td_gd == mycpu) {
  		if ((lp->lwp_flags & LWP_SINTR) ||
  		    (td->td_flags & TDF_SINTR)) {
  			lwkt_schedule(td);
  		}
  		LWPRELE(lp);
  	} else {
  		lwkt_send_ipiq(td->td_gd, lwp_signotify_remote, lp);
  		/* LWPHOLD() is forwarded to the target cpu */
  	}
  }
  
  /*
   * Caller must hold p->p_token
   */
  void
  proc_stop(struct proc *p)
  {
  	struct proc *q;
  	struct lwp *lp;
  
  	ASSERT_LWKT_TOKEN_HELD(&p->p_token);
  
  	/* If somebody raced us, be happy with it */
  	if (p->p_stat == SSTOP || p->p_stat == SZOMB) {
  		return;
  	}
  	p->p_stat = SSTOP;
  
  	FOREACH_LWP_IN_PROC(lp, p) {
  		LWPHOLD(lp);
  		lwkt_gettoken(&lp->lwp_token);
  
  		switch (lp->lwp_stat) {
  		case LSSTOP:
  			/*
  			 * Do nothing, we are already counted in
  			 * p_nstopped.
  			 */
  			break;
  
  		case LSSLEEP:
  			/*
  			 * We're sleeping, but we will stop before
  			 * returning to userspace, so count us
  			 * as stopped as well.  We set LWP_MP_WSTOP
  			 * to signal the lwp that it should not
  			 * increase p_nstopped when reaching tstop().
  			 *
  			 * LWP_MP_WSTOP is protected by lp->lwp_token.
  			 */
  			if ((lp->lwp_mpflags & LWP_MP_WSTOP) == 0) {
  				atomic_set_int(&lp->lwp_mpflags, LWP_MP_WSTOP);
  				++p->p_nstopped;
  			}
  			break;
  
  		case LSRUN:
  			/*
  			 * We might notify ourself, but that's not
  			 * a problem.
  			 */
  			lwp_signotify(lp);
  			break;
  		}
  		lwkt_reltoken(&lp->lwp_token);
  		LWPRELE(lp);
  	}
  
  	if (p->p_nstopped == p->p_nthreads) {
  		/*
  		 * Token required to interlock kern_wait().  Reparenting can
  		 * also cause a race so we have to hold (q).
  		 */
  		q = p->p_pptr;
  		PHOLD(q);
  		lwkt_gettoken(&q->p_token);
  		p->p_flags &= ~P_WAITED;
  		wakeup(q);
  		if ((q->p_sigacts->ps_flag & PS_NOCLDSTOP) == 0)
  			ksignal(p->p_pptr, SIGCHLD);
  		lwkt_reltoken(&q->p_token);
  		PRELE(q);
  	}
  }
  
  /*
   * Caller must hold proc_token
   */
  void
  proc_unstop(struct proc *p)
  {
  	struct lwp *lp;
  
  	ASSERT_LWKT_TOKEN_HELD(&p->p_token);
  
  	if (p->p_stat != SSTOP)
  		return;
  
  	p->p_stat = SACTIVE;
  
  	FOREACH_LWP_IN_PROC(lp, p) {
  		LWPHOLD(lp);
  		lwkt_gettoken(&lp->lwp_token);
  
  		switch (lp->lwp_stat) {
  		case LSRUN:
  			/*
  			 * Uh?  Not stopped?  Well, I guess that's okay.
  			 */
  			if (bootverbose)
  				kprintf("proc_unstop: lwp %d/%d not sleeping\n",
  					p->p_pid, lp->lwp_tid);
  			break;
  
  		case LSSLEEP:
  			/*
  			 * Still sleeping.  Don't bother waking it up.
  			 * However, if this thread was counted as
  			 * stopped, undo this.
  			 *
  			 * Nevertheless we call setrunnable() so that it
  			 * will wake up in case a signal or timeout arrived
  			 * in the meantime.
  			 *
  			 * LWP_MP_WSTOP is protected by lp->lwp_token.
  			 */
  			if (lp->lwp_mpflags & LWP_MP_WSTOP) {
  				atomic_clear_int(&lp->lwp_mpflags,
  						 LWP_MP_WSTOP);
  				--p->p_nstopped;
  			} else {
  				if (bootverbose)
  					kprintf("proc_unstop: lwp %d/%d sleeping, not stopped\n",
  						p->p_pid, lp->lwp_tid);
  			}
  			/* FALLTHROUGH */
  
  		case LSSTOP:
  			/*
  			 * This handles any lwp's waiting in a tsleep with
  			 * SIGCATCH.
  			 */
  			lwp_signotify(lp);
  			break;
  
  		}
  		lwkt_reltoken(&lp->lwp_token);
  		LWPRELE(lp);
  	}
  
  	/*
  	 * This handles any lwp's waiting in tstop().  We have interlocked
  	 * the setting of p_stat by acquiring and releasing each lpw's
  	 * token.
  	 */
  	wakeup(p);
  }
  
  /* 
   * No requirements.
   */
  static int
  kern_sigtimedwait(sigset_t waitset, siginfo_t *info, struct timespec *timeout)
  {
  	sigset_t savedmask, set;
  	struct proc *p = curproc;
  	struct lwp *lp = curthread->td_lwp;
  	int error, sig, hz, timevalid = 0;
  	struct timespec rts, ets, ts;
  	struct timeval tv;
  
  	error = 0;
  	sig = 0;
  	ets.tv_sec = 0;		/* silence compiler warning */
  	ets.tv_nsec = 0;	/* silence compiler warning */
  	SIG_CANTMASK(waitset);
  	savedmask = lp->lwp_sigmask;
  
  	if (timeout) {
  		if (timeout->tv_sec >= 0 && timeout->tv_nsec >= 0 &&
  		    timeout->tv_nsec < 1000000000) {
  			timevalid = 1;
  			getnanouptime(&rts);
  		 	ets = rts;
  			timespecadd(&ets, timeout);
  		}
  	}
  
  	for (;;) {
  		set = lwp_sigpend(lp);
  		SIGSETAND(set, waitset);
  		if ((sig = sig_ffs(&set)) != 0) {
  			SIGFILLSET(lp->lwp_sigmask);
  			SIGDELSET(lp->lwp_sigmask, sig);
  			SIG_CANTMASK(lp->lwp_sigmask);
  			sig = issignal(lp, 1);
  			/*
  			 * It may be a STOP signal, in the case, issignal
  			 * returns 0, because we may stop there, and new
  			 * signal can come in, we should restart if we got
  			 * nothing.
  			 */
  			if (sig == 0)
  				continue;
  			else
  				break;
  		}
  
  		/*
  		 * Previous checking got nothing, and we retried but still
  		 * got nothing, we should return the error status.
  		 */
  		if (error)
  			break;
  
  		/*
  		 * POSIX says this must be checked after looking for pending
  		 * signals.
  		 */
  		if (timeout) {
  			if (timevalid == 0) {
  				error = EINVAL;
  				break;
  			}
  			getnanouptime(&rts);
  			if (timespeccmp(&rts, &ets, >=)) {
  				error = EAGAIN;
  				break;
  			}
  			ts = ets;
  			timespecsub(&ts, &rts);
  			TIMESPEC_TO_TIMEVAL(&tv, &ts);
  			hz = tvtohz_high(&tv);
  		} else {
  			hz = 0;
  		}
  
  		lp->lwp_sigmask = savedmask;
  		SIGSETNAND(lp->lwp_sigmask, waitset);
  		/*
  		 * We won't ever be woken up.  Instead, our sleep will
  		 * be broken in lwpsignal().
  		 */
  		error = tsleep(&p->p_sigacts, PCATCH, "sigwt", hz);
  		if (timeout) {
  			if (error == ERESTART) {
  				/* can not restart a timeout wait. */
  				error = EINTR;
  			} else if (error == EAGAIN) {
  				/* will calculate timeout by ourself. */
  				error = 0;
  			}
  		}
  		/* Retry ... */
  	}
  
  	lp->lwp_sigmask = savedmask;
  	if (sig) {
  		error = 0;
  		bzero(info, sizeof(*info));
  		info->si_signo = sig;
  		spin_lock(&lp->lwp_spin);
  		lwp_delsig(lp, sig);	/* take the signal! */
  		spin_unlock(&lp->lwp_spin);
  
  		if (sig == SIGKILL) {
  			sigexit(lp, sig);
  			/* NOT REACHED */
  		}
  	}
  
  	return (error);
  }
  
  /*
   * MPALMOSTSAFE
   */
  int
  sys_sigtimedwait(struct sigtimedwait_args *uap)
  {
  	struct timespec ts;
  	struct timespec *timeout;
  	sigset_t set;
  	siginfo_t info;
  	int error;
  
  	if (uap->timeout) {
  		error = copyin(uap->timeout, &ts, sizeof(ts));
  		if (error)
  			return (error);
  		timeout = &ts;
  	} else {
  		timeout = NULL;
  	}
  	error = copyin(uap->set, &set, sizeof(set));
  	if (error)
  		return (error);
  	error = kern_sigtimedwait(set, &info, timeout);
  	if (error)
  		return (error);
  	if (uap->info)
  		error = copyout(&info, uap->info, sizeof(info));
  	/* Repost if we got an error. */
  	/*
  	 * XXX lwp
  	 *
  	 * This could transform a thread-specific signal to another
  	 * thread / process pending signal.
  	 */
  	if (error) {
  		ksignal(curproc, info.si_signo);
  	} else {
  		uap->sysmsg_result = info.si_signo;
  	}
  	return (error);
  }
  
  /*
   * MPALMOSTSAFE
   */
  int
  sys_sigwaitinfo(struct sigwaitinfo_args *uap)
  {
  	siginfo_t info;
  	sigset_t set;
  	int error;
  
  	error = copyin(uap->set, &set, sizeof(set));
  	if (error)
  		return (error);
  	error = kern_sigtimedwait(set, &info, NULL);
  	if (error)
  		return (error);
  	if (uap->info)
  		error = copyout(&info, uap->info, sizeof(info));
  	/* Repost if we got an error. */
  	/*
  	 * XXX lwp
  	 *
  	 * This could transform a thread-specific signal to another
  	 * thread / process pending signal.
  	 */
  	if (error) {
  		ksignal(curproc, info.si_signo);
  	} else {
  		uap->sysmsg_result = info.si_signo;
  	}
  	return (error);
  }
  
  /*
   * If the current process has received a signal that would interrupt a
   * system call, return EINTR or ERESTART as appropriate.
   */
  int
  iscaught(struct lwp *lp)
  {
  	struct proc *p = lp->lwp_proc;
  	int sig;
  
  	if (p) {
  		if ((sig = CURSIG(lp)) != 0) {
  			if (SIGISMEMBER(p->p_sigacts->ps_sigintr, sig))
  				return (EINTR);                        
  			return (ERESTART);     
  		}                         
  	}
  	return(EWOULDBLOCK);
  }
  
  /*
   * If the current process has received a signal (should be caught or cause
   * termination, should interrupt current syscall), return the signal number.
   * Stop signals with default action are processed immediately, then cleared;
   * they aren't returned.  This is checked after each entry to the system for
   * a syscall or trap (though this can usually be done without calling issignal
   * by checking the pending signal masks in the CURSIG macro).
   *
   * This routine is called via CURSIG/__cursig.  We will acquire and release
   * p->p_token but if the caller needs to interlock the test the caller must
   * also hold p->p_token.
   *
   *	while (sig = CURSIG(curproc))
   *		postsig(sig);
   *
   * MPSAFE
   */
  int
  issignal(struct lwp *lp, int maytrace)
  {
  	struct proc *p = lp->lwp_proc;
  	sigset_t mask;
  	int sig, prop;
  
  	lwkt_gettoken(&p->p_token);
  
  	for (;;) {
  		int traced = (p->p_flags & P_TRACED) || (p->p_stops & S_SIG);
  
  		/*
  		 * If this process is supposed to stop, stop this thread.
  		 */
  		if (p->p_stat == SSTOP)
  			tstop();
  
  		mask = lwp_sigpend(lp);
  		SIGSETNAND(mask, lp->lwp_sigmask);
  		if (p->p_flags & P_PPWAIT)
  			SIG_STOPSIGMASK(mask);
  		if (SIGISEMPTY(mask)) {		/* no signal to send */
  			lwkt_reltoken(&p->p_token);
  			return (0);
  		}
  		sig = sig_ffs(&mask);
  
  		STOPEVENT(p, S_SIG, sig);
  
  		/*
  		 * We should see pending but ignored signals
  		 * only if P_TRACED was on when they were posted.
  		 */
  		if (SIGISMEMBER(p->p_sigignore, sig) && (traced == 0)) {
  			spin_lock(&lp->lwp_spin);
  			lwp_delsig(lp, sig);
  			spin_unlock(&lp->lwp_spin);
  			continue;
  		}
  		if (maytrace &&
  		    (p->p_flags & P_TRACED) &&
  		    (p->p_flags & P_PPWAIT) == 0) {
  			/*
  			 * If traced, always stop, and stay stopped until
  			 * released by the parent.
  			 *
  			 * NOTE: SSTOP may get cleared during the loop,
  			 * but we do not re-notify the parent if we have 
  			 * to loop several times waiting for the parent
  			 * to let us continue.
  			 *
  			 * XXX not sure if this is still true
  			 */
  			p->p_xstat = sig;
  			proc_stop(p);
  			do {
  				tstop();
  			} while (!trace_req(p) && (p->p_flags & P_TRACED));
  
  			/*
  			 * If parent wants us to take the signal,
  			 * then it will leave it in p->p_xstat;
  			 * otherwise we just look for signals again.
  			 */
  			spin_lock(&lp->lwp_spin);
  			lwp_delsig(lp, sig);	/* clear old signal */
  			spin_unlock(&lp->lwp_spin);
  			sig = p->p_xstat;
  			if (sig == 0)
  				continue;
  
  			/*
  			 * Put the new signal into p_siglist.  If the
  			 * signal is being masked, look for other signals.
  			 *
  			 * XXX lwp might need a call to ksignal()
  			 */
  			SIGADDSET(p->p_siglist, sig);
  			if (SIGISMEMBER(lp->lwp_sigmask, sig))
  				continue;
  
  			/*
  			 * If the traced bit got turned off, go back up
  			 * to the top to rescan signals.  This ensures
  			 * that p_sig* and ps_sigact are consistent.
  			 */
  			if ((p->p_flags & P_TRACED) == 0)
  				continue;
  		}
  
  		prop = sigprop(sig);
  
  		/*
  		 * Decide whether the signal should be returned.
  		 * Return the signal's number, or fall through
  		 * to clear it from the pending mask.
  		 */
  		switch ((intptr_t)p->p_sigacts->ps_sigact[_SIG_IDX(sig)]) {
  		case (intptr_t)SIG_DFL:
  			/*
  			 * Don't take default actions on system processes.
  			 */
  			if (p->p_pid <= 1) {
  #ifdef DIAGNOSTIC
  				/*
  				 * Are you sure you want to ignore SIGSEGV
  				 * in init? XXX
  				 */
  				kprintf("Process (pid %lu) got signal %d\n",
  					(u_long)p->p_pid, sig);
  #endif
  				break;		/* == ignore */
  			}
  
  			/*
  			 * Handle the in-kernel checkpoint action
  			 */
  			if (prop & SA_CKPT) {
  				checkpoint_signal_handler(lp);
  				break;
  			}
  
  			/*
  			 * If there is a pending stop signal to process
  			 * with default action, stop here,
  			 * then clear the signal.  However,
  			 * if process is member of an orphaned
  			 * process group, ignore tty stop signals.
  			 */
  			if (prop & SA_STOP) {
  				if (p->p_flags & P_TRACED ||
  		    		    (p->p_pgrp->pg_jobc == 0 &&
  				    prop & SA_TTYSTOP))
  					break;	/* == ignore */
  				if ((p->p_flags & P_WEXIT) == 0) {
  					p->p_xstat = sig;
  					proc_stop(p);
  					tstop();
  				}
  				break;
  			} else if (prop & SA_IGNORE) {
  				/*
  				 * Except for SIGCONT, shouldn't get here.
  				 * Default action is to ignore; drop it.
  				 */
  				break;		/* == ignore */
  			} else {
  				lwkt_reltoken(&p->p_token);
  				return (sig);
  			}
  
  			/*NOTREACHED*/
  
  		case (intptr_t)SIG_IGN:
  			/*
  			 * Masking above should prevent us ever trying
  			 * to take action on an ignored signal other
  			 * than SIGCONT, unless process is traced.
  			 */
  			if ((prop & SA_CONT) == 0 &&
  			    (p->p_flags & P_TRACED) == 0)
  				kprintf("issignal\n");
  			break;		/* == ignore */
  
  		default:
  			/*
  			 * This signal has an action, let
  			 * postsig() process it.
  			 */
  			lwkt_reltoken(&p->p_token);
  			return (sig);
  		}
  		spin_lock(&lp->lwp_spin);
  		lwp_delsig(lp, sig);		/* take the signal! */
  		spin_unlock(&lp->lwp_spin);
  	}
  	/* NOTREACHED */
  }
  
  /*
   * Take the action for the specified signal
   * from the current set of pending signals.
   *
   * Caller must hold p->p_token
   */
  void
  postsig(int sig)
  {
  	struct lwp *lp = curthread->td_lwp;
  	struct proc *p = lp->lwp_proc;
  	struct sigacts *ps = p->p_sigacts;
  	sig_t action;
  	sigset_t returnmask;
  	int code;
  
  	KASSERT(sig != 0, ("postsig"));
  
  	KNOTE(&p->p_klist, NOTE_SIGNAL | sig);
  
  	/*
  	 * If we are a virtual kernel running an emulated user process
  	 * context, switch back to the virtual kernel context before
  	 * trying to post the signal.
  	 */
  	if (lp->lwp_vkernel && lp->lwp_vkernel->ve) {
  		struct trapframe *tf = lp->lwp_md.md_regs;
  		tf->tf_trapno = 0;
  		vkernel_trap(lp, tf);
  	}
  
  	spin_lock(&lp->lwp_spin);
  	lwp_delsig(lp, sig);
  	spin_unlock(&lp->lwp_spin);
  	action = ps->ps_sigact[_SIG_IDX(sig)];
  #ifdef KTRACE
  	if (KTRPOINT(lp->lwp_thread, KTR_PSIG))
  		ktrpsig(lp, sig, action, lp->lwp_flags & LWP_OLDMASK ?
  			&lp->lwp_oldsigmask : &lp->lwp_sigmask, 0);
  #endif
  	STOPEVENT(p, S_SIG, sig);
  
  	if (action == SIG_DFL) {
  		/*
  		 * Default action, where the default is to kill
  		 * the process.  (Other cases were ignored above.)
  		 */
  		sigexit(lp, sig);
  		/* NOTREACHED */
  	} else {
  		/*
  		 * If we get here, the signal must be caught.
  		 */
  		KASSERT(action != SIG_IGN && !SIGISMEMBER(lp->lwp_sigmask, sig),
  		    ("postsig action"));
  
  		/*
  		 * Reset the signal handler if asked to
  		 */
  		if (SIGISMEMBER(ps->ps_sigreset, sig)) {
  			/*
  			 * See kern_sigaction() for origin of this code.
  			 */
  			SIGDELSET(p->p_sigcatch, sig);
  			if (sig != SIGCONT &&
  			    sigprop(sig) & SA_IGNORE)
  				SIGADDSET(p->p_sigignore, sig);
  			ps->ps_sigact[_SIG_IDX(sig)] = SIG_DFL;
  		}
  
  		/*
  		 * Set the signal mask and calculate the mask to restore
  		 * when the signal function returns.
  		 *
  		 * Special case: user has done a sigsuspend.  Here the
  		 * current mask is not of interest, but rather the
  		 * mask from before the sigsuspend is what we want
  		 * restored after the signal processing is completed.
  		 */
  		if (lp->lwp_flags & LWP_OLDMASK) {
  			returnmask = lp->lwp_oldsigmask;
  			lp->lwp_flags &= ~LWP_OLDMASK;
  		} else {
  			returnmask = lp->lwp_sigmask;
  		}
  
  		SIGSETOR(lp->lwp_sigmask, ps->ps_catchmask[_SIG_IDX(sig)]);
  		if (!SIGISMEMBER(ps->ps_signodefer, sig))
  			SIGADDSET(lp->lwp_sigmask, sig);
  
  		lp->lwp_ru.ru_nsignals++;
  		if (lp->lwp_sig != sig) {
  			code = 0;
  		} else {
  			code = lp->lwp_code;
  			lp->lwp_code = 0;
  			lp->lwp_sig = 0;
  		}
  		(*p->p_sysent->sv_sendsig)(action, sig, &returnmask, code);
  	}
  }
  
  /*
   * Kill the current process for stated reason.
   */
  void
  killproc(struct proc *p, char *why)
  {
  	log(LOG_ERR, "pid %d (%s), uid %d, was killed: %s\n", 
  		p->p_pid, p->p_comm,
  		p->p_ucred ? p->p_ucred->cr_uid : -1, why);
  	ksignal(p, SIGKILL);
  }
  
  /*
   * Force the current process to exit with the specified signal, dumping core
   * if appropriate.  We bypass the normal tests for masked and caught signals,
   * allowing unrecoverable failures to terminate the process without changing
   * signal state.  Mark the accounting record with the signal termination.
   * If dumping core, save the signal number for the debugger.  Calls exit and
   * does not return.
   *
   * This routine does not return.
   */
  void
  sigexit(struct lwp *lp, int sig)
  {
  	struct proc *p = lp->lwp_proc;
  
  	lwkt_gettoken(&p->p_token);
  	p->p_acflag |= AXSIG;
  	if (sigprop(sig) & SA_CORE) {
  		lp->lwp_sig = sig;
  		/*
  		 * Log signals which would cause core dumps
  		 * (Log as LOG_INFO to appease those who don't want
  		 * these messages.)
  		 * XXX : Todo, as well as euid, write out ruid too
  		 */
  		if (coredump(lp, sig) == 0)
  			sig |= WCOREFLAG;
  		if (kern_logsigexit)
  			log(LOG_INFO,
  			    "pid %d (%s), uid %d: exited on signal %d%s\n",
  			    p->p_pid, p->p_comm,
  			    p->p_ucred ? p->p_ucred->cr_uid : -1,
  			    sig &~ WCOREFLAG,
  			    sig & WCOREFLAG ? " (core dumped)" : "");
  	}
  	lwkt_reltoken(&p->p_token);
  	exit1(W_EXITCODE(0, sig));
  	/* NOTREACHED */
  }
  
  static char corefilename[MAXPATHLEN+1] = {"%N.core"};
  SYSCTL_STRING(_kern, OID_AUTO, corefile, CTLFLAG_RW, corefilename,
  	      sizeof(corefilename), "process corefile name format string");
  
  /*
   * expand_name(name, uid, pid)
   * Expand the name described in corefilename, using name, uid, and pid.
   * corefilename is a kprintf-like string, with three format specifiers:
   *	%N	name of process ("name")
   *	%P	process id (pid)
   *	%U	user id (uid)
   * For example, "%N.core" is the default; they can be disabled completely
   * by using "/dev/null", or all core files can be stored in "/cores/%U/%N-%P".
   * This is controlled by the sysctl variable kern.corefile (see above).
   */
  
  static char *
  expand_name(const char *name, uid_t uid, pid_t pid)
  {
  	char *temp;
  	char buf[11];		/* Buffer for pid/uid -- max 4B */
  	int i, n;
  	char *format = corefilename;
  	size_t namelen;
  
  	temp = kmalloc(MAXPATHLEN + 1, M_TEMP, M_NOWAIT);
  	if (temp == NULL)
  		return NULL;
  	namelen = strlen(name);
  	for (i = 0, n = 0; n < MAXPATHLEN && format[i]; i++) {
  		int l;
  		switch (format[i]) {
  		case '%':	/* Format character */
  			i++;
  			switch (format[i]) {
  			case '%':
  				temp[n++] = '%';
  				break;
  			case 'N':	/* process name */
  				if ((n + namelen) > MAXPATHLEN) {
  					log(LOG_ERR, "pid %d (%s), uid (%u):  Path `%s%s' is too long\n",
  					    pid, name, uid, temp, name);
  					kfree(temp, M_TEMP);
  					return NULL;
  				}
  				memcpy(temp+n, name, namelen);
  				n += namelen;
  				break;
  			case 'P':	/* process id */
  				l = ksprintf(buf, "%u", pid);
  				if ((n + l) > MAXPATHLEN) {
  					log(LOG_ERR, "pid %d (%s), uid (%u):  Path `%s%s' is too long\n",
  					    pid, name, uid, temp, name);
  					kfree(temp, M_TEMP);
  					return NULL;
  				}
  				memcpy(temp+n, buf, l);
  				n += l;
  				break;
  			case 'U':	/* user id */
  				l = ksprintf(buf, "%u", uid);
  				if ((n + l) > MAXPATHLEN) {
  					log(LOG_ERR, "pid %d (%s), uid (%u):  Path `%s%s' is too long\n",
  					    pid, name, uid, temp, name);
  					kfree(temp, M_TEMP);
  					return NULL;
  				}
  				memcpy(temp+n, buf, l);
  				n += l;
  				break;
  			default:
  			  	log(LOG_ERR, "Unknown format character %c in `%s'\n", format[i], format);
  			}
  			break;
  		default:
  			temp[n++] = format[i];
  		}
  	}
  	temp[n] = '\0';
  	return temp;
  }
  
  /*
   * Dump a process' core.  The main routine does some
   * policy checking, and creates the name of the coredump;
   * then it passes on a vnode and a size limit to the process-specific
   * coredump routine if there is one; if there _is not_ one, it returns
   * ENOSYS; otherwise it returns the error from the process-specific routine.
   *
   * The parameter `lp' is the lwp which triggered the coredump.
   */
  
  static int
  coredump(struct lwp *lp, int sig)
  {
  	struct proc *p = lp->lwp_proc;
  	struct vnode *vp;
  	struct ucred *cred = p->p_ucred;
  	struct flock lf;
  	struct nlookupdata nd;
  	struct vattr vattr;
  	int error, error1;
  	char *name;			/* name of corefile */
  	off_t limit;
  	
  	STOPEVENT(p, S_CORE, 0);
  
  	if (((sugid_coredump == 0) && p->p_flags & P_SUGID) || do_coredump == 0)
  		return (EFAULT);
  	
  	/*
  	 * Note that the bulk of limit checking is done after
  	 * the corefile is created.  The exception is if the limit
  	 * for corefiles is 0, in which case we don't bother
  	 * creating the corefile at all.  This layout means that
  	 * a corefile is truncated instead of not being created,
  	 * if it is larger than the limit.
  	 */
  	limit = p->p_rlimit[RLIMIT_CORE].rlim_cur;
  	if (limit == 0)
  		return EFBIG;
  
  	name = expand_name(p->p_comm, p->p_ucred->cr_uid, p->p_pid);
  	if (name == NULL)
  		return (EINVAL);
  	error = nlookup_init(&nd, name, UIO_SYSSPACE, NLC_LOCKVP);
  	if (error == 0)
  		error = vn_open(&nd, NULL, O_CREAT | FWRITE | O_NOFOLLOW, S_IRUSR | S_IWUSR);
  	kfree(name, M_TEMP);
  	if (error) {
  		nlookup_done(&nd);
  		return (error);
  	}
  	vp = nd.nl_open_vp;
  	nd.nl_open_vp = NULL;
  	nlookup_done(&nd);
  
  	vn_unlock(vp);
  	lf.l_whence = SEEK_SET;
  	lf.l_start = 0;
  	lf.l_len = 0;
  	lf.l_type = F_WRLCK;
  	error = VOP_ADVLOCK(vp, (caddr_t)p, F_SETLK, &lf, 0);
  	if (error)
  		goto out2;
  
  	/* Don't dump to non-regular files or files with links. */
  	if (vp->v_type != VREG ||
  	    VOP_GETATTR(vp, &vattr) || vattr.va_nlink != 1) {
  		error = EFAULT;
  		goto out1;
  	}
  
  	/* Don't dump to files current user does not own */
  	if (vattr.va_uid != p->p_ucred->cr_uid) {
  		error = EFAULT;
  		goto out1;
  	}
  
  	VATTR_NULL(&vattr);
  	vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
  	vattr.va_size = 0;
  	VOP_SETATTR(vp, &vattr, cred);
  	p->p_acflag |= ACORE;
  	vn_unlock(vp);
  
  	error = p->p_sysent->sv_coredump ?
  		  p->p_sysent->sv_coredump(lp, sig, vp, limit) : ENOSYS;
  
  out1:
  	lf.l_type = F_UNLCK;
  	VOP_ADVLOCK(vp, (caddr_t)p, F_UNLCK, &lf, 0);
  out2:
  	error1 = vn_close(vp, FWRITE);
  	if (error == 0)
  		error = error1;
  	return (error);
  }
  
  /*
   * Nonexistent system call-- signal process (may want to handle it).
   * Flag error in case process won't see signal immediately (blocked or ignored).
   *
   * MPALMOSTSAFE
   */
  /* ARGSUSED */
  int
  sys_nosys(struct nosys_args *args)
  {
  	lwpsignal(curproc, curthread->td_lwp, SIGSYS);
  	return (EINVAL);
  }
  
  /*
   * Send a SIGIO or SIGURG signal to a process or process group using
   * stored credentials rather than those of the current process.
   */
  void
  pgsigio(struct sigio *sigio, int sig, int checkctty)
  {
  	if (sigio == NULL)
  		return;
  		
  	if (sigio->sio_pgid > 0) {
  		if (CANSIGIO(sigio->sio_ruid, sigio->sio_ucred,
  		             sigio->sio_proc))
  			ksignal(sigio->sio_proc, sig);
  	} else if (sigio->sio_pgid < 0) {
  		struct proc *p;
  		struct pgrp *pg = sigio->sio_pgrp;
  
  		/*
  		 * Must interlock all signals against fork
  		 */
  		pgref(pg);
  		lockmgr(&pg->pg_lock, LK_EXCLUSIVE);
  		LIST_FOREACH(p, &pg->pg_members, p_pglist) {
  			if (CANSIGIO(sigio->sio_ruid, sigio->sio_ucred, p) &&
  			    (checkctty == 0 || (p->p_flags & P_CONTROLT)))
  				ksignal(p, sig);
  		}
  		lockmgr(&pg->pg_lock, LK_RELEASE);
  		pgrel(pg);
  	}
  }
  
  static int
  filt_sigattach(struct knote *kn)
  {
  	struct proc *p = curproc;
  
  	kn->kn_ptr.p_proc = p;
  	kn->kn_flags |= EV_CLEAR;		/* automatically set */
  
  	/* XXX lock the proc here while adding to the list? */
  	knote_insert(&p->p_klist, kn);
  
  	return (0);
  }
  
  static void
  filt_sigdetach(struct knote *kn)
  {
  	struct proc *p = kn->kn_ptr.p_proc;
  
  	knote_remove(&p->p_klist, kn);
  }
  
  /*
   * signal knotes are shared with proc knotes, so we apply a mask to 
   * the hint in order to differentiate them from process hints.  This
   * could be avoided by using a signal-specific knote list, but probably
   * isn't worth the trouble.
   */
  static int
  filt_signal(struct knote *kn, long hint)
  {
  	if (hint & NOTE_SIGNAL) {
  		hint &= ~NOTE_SIGNAL;
  
  		if (kn->kn_id == hint)
  			kn->kn_data++;
  	}
  	return (kn->kn_data != 0);
  }
  