This patchset fixes a large number of file descriptor race conditions.

    Pre-rfork code assumed inherent locking of a process's file descriptor
    array.  However, with the advent of rfork() the file descriptor table
    could be shared between processes.  This patch closes over a dozen
    serious race conditions related to one thread manipulating the table
    (e.g. closing or dup()ing a descriptor) while another is blocked in
    an open(), close(), fcntl(), read(), write(), etc...

PR: kern/11629
Discussed with: Alexander Viro <viro@math.psu.edu>

1 files changed, 666 insertions, 0 deletions

diff --git a/sys/svr4/svr4_signal.c b/sys/svr4/svr4_signal.c
new file mode 100644
index 0000000..46407ba
--- /dev/null
+++ b/sys/svr4/svr4_signal.c
@@ -0,0 +1,666 @@
+/*
+ * Copyright (c) 1998 Mark Newton
+ * Copyright (c) 1994 Christos Zoulas
+ * All rights reserved.
+ *
+ * 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. The name of the author may not be used to endorse or promote products
+ *    derived from this software without specific prior written permission
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
+ * 
+ * $FreeBSD$
+ */
+
+#include <sys/param.h>
+#include <sys/systm.h>
+#include <sys/proc.h>
+#include <sys/filedesc.h>
+#include <sys/signal.h>
+#include <sys/signalvar.h>
+#include <sys/sysproto.h>
+
+#include <svr4/svr4.h>
+#include <svr4/svr4_types.h>
+#include <svr4/svr4_signal.h>
+#include <svr4/svr4_proto.h>
+#include <svr4/svr4_util.h>
+#include <svr4/svr4_ucontext.h>
+
+#define	svr4_sigmask(n)		(1 << (((n) - 1) & 31))
+#define	svr4_sigword(n)		(((n) - 1) >> 5)
+#define svr4_sigemptyset(s)	memset((s), 0, sizeof(*(s)))
+#define	svr4_sigismember(s, n)	((s)->bits[svr4_sigword(n)] & svr4_sigmask(n))
+#define	svr4_sigaddset(s, n)	((s)->bits[svr4_sigword(n)] |= svr4_sigmask(n))
+
+void svr4_to_bsd_sigaction __P((const struct svr4_sigaction *,
+				struct sigaction *));
+void bsd_to_svr4_sigaction __P((const struct sigaction *,
+				struct svr4_sigaction *));
+void svr4_sigfillset __P((svr4_sigset_t *));
+
+int bsd_to_svr4_sig[SVR4_SIGTBLSZ] = {
+	SVR4_SIGHUP,
+	SVR4_SIGINT,
+	SVR4_SIGQUIT,
+	SVR4_SIGILL,
+	SVR4_SIGTRAP,
+	SVR4_SIGABRT,
+	SVR4_SIGEMT,
+	SVR4_SIGFPE,
+	SVR4_SIGKILL,
+	SVR4_SIGBUS,
+	SVR4_SIGSEGV,
+	SVR4_SIGSYS,
+	SVR4_SIGPIPE,
+	SVR4_SIGALRM,
+	SVR4_SIGTERM,
+	SVR4_SIGURG,
+	SVR4_SIGSTOP,
+	SVR4_SIGTSTP,
+	SVR4_SIGCONT,
+	SVR4_SIGCHLD,
+	SVR4_SIGTTIN,
+	SVR4_SIGTTOU,
+	SVR4_SIGIO,
+	SVR4_SIGXCPU,
+	SVR4_SIGXFSZ,
+	SVR4_SIGVTALRM,
+	SVR4_SIGPROF,
+	SVR4_SIGWINCH,
+	0,			/* SIGINFO */
+	SVR4_SIGUSR1,
+	SVR4_SIGUSR2,
+};
+
+int svr4_to_bsd_sig[SVR4_SIGTBLSZ] = {
+	SIGHUP,
+	SIGINT,
+	SIGQUIT,
+	SIGILL,
+	SIGTRAP,
+	SIGABRT,
+	SIGEMT,
+	SIGFPE,
+	SIGKILL,
+	SIGBUS,
+	SIGSEGV,
+	SIGSYS,
+	SIGPIPE,
+	SIGALRM,
+	SIGTERM,
+	SIGUSR1,
+	SIGUSR2,
+	SIGCHLD,
+	0,		/* XXX NetBSD uses SIGPWR here, but we don't seem to have one */
+	SIGWINCH,
+	SIGURG,
+	SIGIO,
+	SIGSTOP,
+	SIGTSTP,
+	SIGCONT,
+	SIGTTIN,
+	SIGTTOU,
+	SIGVTALRM,
+	SIGPROF,
+	SIGXCPU,
+	SIGXFSZ,
+};
+
+void
+svr4_sigfillset(s)
+	svr4_sigset_t *s;
+{
+	int i;
+
+	svr4_sigemptyset(s);
+	for (i = 0; i < SVR4_NSIG; i++) 
+		if (svr4_to_bsd_sig[i] != 0)
+			svr4_sigaddset(s, i);
+}
+
+void
+svr4_to_bsd_sigset(sss, bss)
+	const svr4_sigset_t *sss;
+	sigset_t *bss;
+{
+	int i, newsig;
+
+	SIGEMPTYSET(*bss);
+	for (i = 0; i < SVR4_NSIG; i++)
+		if (svr4_sigismember(sss, i + 1)) {
+			newsig = svr4_to_bsd_sig[i];
+			if (newsig)
+				SIGADDSET(*bss, newsig);
+		}
+}
+
+void
+bsd_to_svr4_sigset(bss, sss)
+	const sigset_t *bss;
+	svr4_sigset_t *sss;
+{
+	int i, newsig;
+
+	svr4_sigemptyset(sss);
+	sss->bits[0] = bss->__bits[0] & ~((1U << SVR4_SIGTBLSZ) - 1);
+	sss->bits[1] = bss->__bits[1];
+	sss->bits[2] = bss->__bits[2];
+	sss->bits[3] = bss->__bits[3];
+	for (i = 1; i <= SVR4_SIGTBLSZ; i++) {
+		if (SIGISMEMBER(*bss, i)) {
+			newsig = bsd_to_svr4_sig[_SIG_IDX(i)];
+			if (newsig)
+				svr4_sigaddset(sss, newsig);
+		}
+	}
+}
+
+/*
+ * XXX: Only a subset of the flags is currently implemented.
+ */
+void
+svr4_to_bsd_sigaction(ssa, bsa)
+	const struct svr4_sigaction *ssa;
+	struct sigaction *bsa;
+{
+
+	bsa->sa_handler = (sig_t) ssa->ssa_handler;
+	svr4_to_bsd_sigset(&ssa->ssa_mask, &bsa->sa_mask);
+	bsa->sa_flags = 0;
+	if ((ssa->ssa_flags & SVR4_SA_ONSTACK) != 0)
+		bsa->sa_flags |= SA_ONSTACK;
+	if ((ssa->ssa_flags & SVR4_SA_RESETHAND) != 0)
+		bsa->sa_flags |= SA_RESETHAND;
+	if ((ssa->ssa_flags & SVR4_SA_RESTART) != 0)
+		bsa->sa_flags |= SA_RESTART;
+	if ((ssa->ssa_flags & SVR4_SA_SIGINFO) != 0)
+		DPRINTF(("svr4_to_bsd_sigaction: SA_SIGINFO ignored\n"));
+	if ((ssa->ssa_flags & SVR4_SA_NOCLDSTOP) != 0)
+		bsa->sa_flags |= SA_NOCLDSTOP;
+	if ((ssa->ssa_flags & SVR4_SA_NODEFER) != 0)
+		bsa->sa_flags |= SA_NODEFER;
+	if ((ssa->ssa_flags & SVR4_SA_NOCLDWAIT) != 0)
+		bsa->sa_flags |= SA_NOCLDWAIT;
+	if ((ssa->ssa_flags & ~SVR4_SA_ALLBITS) != 0)
+		DPRINTF(("svr4_to_bsd_sigaction: extra bits ignored\n"));
+}
+
+void
+bsd_to_svr4_sigaction(bsa, ssa)
+	const struct sigaction *bsa;
+	struct svr4_sigaction *ssa;
+{
+
+	ssa->ssa_handler = (svr4_sig_t) bsa->sa_handler;
+	bsd_to_svr4_sigset(&bsa->sa_mask, &ssa->ssa_mask);
+	ssa->ssa_flags = 0;
+	if ((bsa->sa_flags & SA_ONSTACK) != 0)
+		ssa->ssa_flags |= SVR4_SA_ONSTACK;
+	if ((bsa->sa_flags & SA_RESETHAND) != 0)
+		ssa->ssa_flags |= SVR4_SA_RESETHAND;
+	if ((bsa->sa_flags & SA_RESTART) != 0)
+		ssa->ssa_flags |= SVR4_SA_RESTART;
+	if ((bsa->sa_flags & SA_NODEFER) != 0)
+		ssa->ssa_flags |= SVR4_SA_NODEFER;
+	if ((bsa->sa_flags & SA_NOCLDSTOP) != 0)
+		ssa->ssa_flags |= SVR4_SA_NOCLDSTOP;
+}
+
+void
+svr4_to_bsd_sigaltstack(sss, bss)
+	const struct svr4_sigaltstack *sss;
+	struct sigaltstack *bss;
+{
+
+	bss->ss_sp = sss->ss_sp;
+	bss->ss_size = sss->ss_size;
+	bss->ss_flags = 0;
+	if ((sss->ss_flags & SVR4_SS_DISABLE) != 0)
+		bss->ss_flags |= SS_DISABLE;
+	if ((sss->ss_flags & SVR4_SS_ONSTACK) != 0)
+		bss->ss_flags |= SS_ONSTACK;
+	if ((sss->ss_flags & ~SVR4_SS_ALLBITS) != 0)
+	  /*XXX*/ uprintf("svr4_to_bsd_sigaltstack: extra bits ignored\n");
+}
+
+void
+bsd_to_svr4_sigaltstack(bss, sss)
+	const struct sigaltstack *bss;
+	struct svr4_sigaltstack *sss;
+{
+
+	sss->ss_sp = bss->ss_sp;
+	sss->ss_size = bss->ss_size;
+	sss->ss_flags = 0;
+	if ((bss->ss_flags & SS_DISABLE) != 0)
+		sss->ss_flags |= SVR4_SS_DISABLE;
+	if ((bss->ss_flags & SS_ONSTACK) != 0)
+		sss->ss_flags |= SVR4_SS_ONSTACK;
+}
+
+int
+svr4_sys_sigaction(p, uap)
+	register struct proc *p;
+	struct svr4_sys_sigaction_args *uap;
+{
+	struct svr4_sigaction *nisa, *oisa, tmpisa;
+	struct sigaction *nbsa, *obsa, tmpbsa;
+	struct sigaction_args sa;
+	caddr_t sg;
+	int error;
+
+	DPRINTF(("@@@ svr4_sys_sigaction(%d, %d, %d)\n", p->p_pid,
+			SCARG(uap, signum),
+			SVR4_SVR42BSD_SIG(SCARG(uap, signum))));
+	
+	sg = stackgap_init();
+	nisa = SCARG(uap, nsa);
+	oisa = SCARG(uap, osa);
+
+	if (oisa != NULL)
+		obsa = stackgap_alloc(&sg, sizeof(struct sigaction));
+	else
+		obsa = NULL;
+
+	if (nisa != NULL) {
+		nbsa = stackgap_alloc(&sg, sizeof(struct sigaction));
+		if ((error = copyin(nisa, &tmpisa, sizeof(tmpisa))) != 0)
+			return error;
+		svr4_to_bsd_sigaction(&tmpisa, &tmpbsa);
+		if ((error = copyout(&tmpbsa, nbsa, sizeof(tmpbsa))) != 0)
+			return error;
+	} else
+		nbsa = NULL;
+
+#if defined(DEBUG_SVR4)
+	{
+		int i;
+		for (i = 0; i < 4; i++) 
+			DPRINTF(("\tssa_mask[%d] = %lx\n", i,
+						nisa->ssa_mask.bits[i]));
+		DPRINTF(("\tssa_handler = %lx\n", nisa->ssa_handler));
+	}
+#endif
+
+	SCARG(&sa, sig) = SVR4_SVR42BSD_SIG(SCARG(uap, signum));
+	SCARG(&sa, act) = nbsa;
+	SCARG(&sa, oact) = obsa;
+
+	if ((error = sigaction(p, &sa)) != 0)
+		return error;
+
+	if (oisa != NULL) {
+		if ((error = copyin(obsa, &tmpbsa, sizeof(tmpbsa))) != 0)
+			return error;
+		bsd_to_svr4_sigaction(&tmpbsa, &tmpisa);
+		if ((error = copyout(&tmpisa, oisa, sizeof(tmpisa))) != 0)
+			return error;
+	}
+
+	return 0;
+}
+
+int 
+svr4_sys_sigaltstack(p, uap)
+	register struct proc *p;
+	struct svr4_sys_sigaltstack_args *uap;
+{
+	struct svr4_sigaltstack *nsss, *osss, tmpsss;
+	struct sigaltstack *nbss, *obss, tmpbss;
+	struct sigaltstack_args sa;
+	caddr_t sg;
+	int error, *retval;
+
+	retval = p->p_retval;
+	sg = stackgap_init();
+	nsss = SCARG(uap, nss);
+	osss = SCARG(uap, oss);
+
+	if (osss != NULL)
+		obss = stackgap_alloc(&sg, sizeof(struct sigaltstack));
+	else
+		obss = NULL;
+
+	if (nsss != NULL) {
+		nbss = stackgap_alloc(&sg, sizeof(struct sigaltstack));
+		if ((error = copyin(nsss, &tmpsss, sizeof(tmpsss))) != 0)
+			return error;
+		svr4_to_bsd_sigaltstack(&tmpsss, &tmpbss);
+		if ((error = copyout(&tmpbss, nbss, sizeof(tmpbss))) != 0)
+			return error;
+	} else
+		nbss = NULL;
+
+	SCARG(&sa, ss) = nbss;
+	SCARG(&sa, oss) = obss;
+
+	if ((error = sigaltstack(p, &sa)) != 0)
+		return error;
+
+	if (obss != NULL) {
+		if ((error = copyin(obss, &tmpbss, sizeof(tmpbss))) != 0)
+			return error;
+		bsd_to_svr4_sigaltstack(&tmpbss, &tmpsss);
+		if ((error = copyout(&tmpsss, osss, sizeof(tmpsss))) != 0)
+			return error;
+	}
+
+	return 0;
+}
+
+/*
+ * Stolen from the ibcs2 one
+ */
+int
+svr4_sys_signal(p, uap)
+	register struct proc *p;
+	struct svr4_sys_signal_args *uap;
+{
+	int signum;
+	int error, *retval = p->p_retval;
+	caddr_t sg = stackgap_init();
+
+	DPRINTF(("@@@ svr4_sys_signal(%d)\n", p->p_pid));
+
+	signum = SVR4_SVR42BSD_SIG(SVR4_SIGNO(SCARG(uap, signum)));
+	if (signum <= 0 || signum > SVR4_NSIG)
+		return (EINVAL);
+
+	switch (SVR4_SIGCALL(SCARG(uap, signum))) {
+	case SVR4_SIGDEFER_MASK:
+		if (SCARG(uap, handler) == SVR4_SIG_HOLD)
+			goto sighold;
+		/* FALLTHROUGH */
+
+	case SVR4_SIGNAL_MASK:
+		{
+			struct sigaction_args sa_args;
+			struct sigaction *nbsa, *obsa, sa;
+
+			nbsa = stackgap_alloc(&sg, sizeof(struct sigaction));
+			obsa = stackgap_alloc(&sg, sizeof(struct sigaction));
+			SCARG(&sa_args, sig) = signum;
+			SCARG(&sa_args, act) = nbsa;
+			SCARG(&sa_args, oact) = obsa;
+
+			sa.sa_handler = (sig_t) SCARG(uap, handler);
+			SIGEMPTYSET(sa.sa_mask);
+			sa.sa_flags = 0;
+
+			if (signum != SIGALRM)
+				sa.sa_flags = SA_RESTART;
+
+			if ((error = copyout(&sa, nbsa, sizeof(sa))) != 0)
+				return error;
+			if ((error = sigaction(p, &sa_args)) != 0) {
+				DPRINTF(("signal: sigaction failed: %d\n",
+					 error));
+				*retval = (int)SVR4_SIG_ERR;
+				return error;
+			}
+			if ((error = copyin(obsa, &sa, sizeof(sa))) != 0)
+				return error;
+			*retval = (int)sa.sa_handler;
+			return 0;
+		}
+
+	case SVR4_SIGHOLD_MASK:
+sighold:
+		{
+			struct sigprocmask_args sa;
+			sigset_t *set;
+
+			set = stackgap_alloc(&sg, sizeof(sigset_t));
+			SIGEMPTYSET(*set);
+			SIGADDSET(*set, signum);
+			SCARG(&sa, how) = SIG_BLOCK;
+			SCARG(&sa, set) = set;
+			SCARG(&sa, oset) = NULL;
+			return sigprocmask(p, &sa);
+		}
+
+	case SVR4_SIGRELSE_MASK:
+		{
+			struct sigprocmask_args sa;
+			sigset_t *set;
+
+			set = stackgap_alloc(&sg, sizeof(sigset_t));
+			SIGEMPTYSET(*set);
+			SIGADDSET(*set, signum);
+			SCARG(&sa, how) = SIG_UNBLOCK;
+			SCARG(&sa, set) = set;
+			SCARG(&sa, oset) = NULL;
+			return sigprocmask(p, &sa);
+		}
+
+	case SVR4_SIGIGNORE_MASK:
+		{
+			struct sigaction_args sa_args;
+			struct sigaction *bsa, sa;
+
+			bsa = stackgap_alloc(&sg, sizeof(struct sigaction));
+			SCARG(&sa_args, sig) = signum;
+			SCARG(&sa_args, act) = bsa;
+			SCARG(&sa_args, oact) = NULL;
+
+			sa.sa_handler = SIG_IGN;
+			SIGEMPTYSET(sa.sa_mask);
+			sa.sa_flags = 0;
+			if ((error = copyout(&sa, bsa, sizeof(sa))) != 0)
+				return error;
+			if ((error = sigaction(p, &sa_args)) != 0) {
+				DPRINTF(("sigignore: sigaction failed\n"));
+				return error;
+			}
+			return 0;
+		}
+
+	case SVR4_SIGPAUSE_MASK:
+		{
+			struct sigsuspend_args sa;
+			sigset_t *set;
+
+			set = stackgap_alloc(&sg, sizeof(sigset_t));
+			*set = p->p_sigmask;
+			SIGDELSET(*set, signum);
+			SCARG(&sa, sigmask) = set;
+			return sigsuspend(p, &sa);
+		}
+
+	default:
+		return (ENOSYS);
+	}
+}
+
+
+int
+svr4_sys_sigprocmask(p, uap)
+	struct proc *p;
+	struct svr4_sys_sigprocmask_args *uap;
+{
+	svr4_sigset_t sss;
+	sigset_t bss;
+	int error = 0, *retval;
+
+	retval = p->p_retval;
+	if (SCARG(uap, oset) != NULL) {
+		/* Fix the return value first if needed */
+		bsd_to_svr4_sigset(&p->p_sigmask, &sss);
+		if ((error = copyout(&sss, SCARG(uap, oset), sizeof(sss))) != 0)
+			return error;
+	}
+
+	if (SCARG(uap, set) == NULL)
+		/* Just examine */
+		return 0;
+
+	if ((error = copyin(SCARG(uap, set), &sss, sizeof(sss))) != 0)
+		return error;
+
+	svr4_to_bsd_sigset(&sss, &bss);
+
+	mtx_enter_sched_quick();
+
+	switch (SCARG(uap, how)) {
+	case SVR4_SIG_BLOCK:
+		SIGSETOR(p->p_sigmask, bss);
+		SIG_CANTMASK(p->p_sigmask);
+		break;
+
+	case SVR4_SIG_UNBLOCK:
+		SIGSETNAND(p->p_sigmask, bss);
+		break;
+
+	case SVR4_SIG_SETMASK:
+		p->p_sigmask = bss;
+		SIG_CANTMASK(p->p_sigmask);
+		break;
+
+	default:
+		error = EINVAL;
+		break;
+	}
+
+	mtx_exit_sched_quick();
+
+	return error;
+}
+
+int
+svr4_sys_sigpending(p, uap)
+	struct proc *p;
+	struct svr4_sys_sigpending_args *uap;
+{
+	sigset_t bss;
+	int *retval;
+	svr4_sigset_t sss;
+
+	DPRINTF(("@@@ svr4_sys_sigpending(%d)\n", p->p_pid));
+	retval = p->p_retval;
+	switch (SCARG(uap, what)) {
+	case 1:	/* sigpending */
+		if (SCARG(uap, mask) == NULL)
+			return 0;
+		bss = p->p_siglist;
+		SIGSETAND(bss, p->p_sigmask);
+		bsd_to_svr4_sigset(&bss, &sss);
+		break;
+
+	case 2:	/* sigfillset */
+		svr4_sigfillset(&sss);
+#if defined(DEBUG_SVR4)
+		{
+			int i;
+			for (i = 0; i < 4; i++)
+				DPRINTF(("new sigset[%d] = %lx\n", i, (long)sss.bits[i]));
+		}
+#endif
+		break;
+
+	default:
+		return EINVAL;
+	}
+		
+	return copyout(&sss, SCARG(uap, mask), sizeof(sss));
+}
+
+int
+svr4_sys_sigsuspend(p, uap)
+	register struct proc *p;
+	struct svr4_sys_sigsuspend_args *uap;
+{
+	svr4_sigset_t sss;
+	sigset_t *bss;
+	struct sigsuspend_args sa;
+	int error;
+	caddr_t sg = stackgap_init();
+
+	if ((error = copyin(SCARG(uap, ss), &sss, sizeof(sss))) != 0)
+		return error;
+
+	bss = stackgap_alloc(&sg, sizeof(sigset_t));
+	svr4_to_bsd_sigset(&sss, bss);
+
+	SCARG(&sa, sigmask) = bss;
+	return sigsuspend(p, &sa);
+}
+
+
+int
+svr4_sys_kill(p, uap)
+	register struct proc *p;
+	struct svr4_sys_kill_args *uap;
+{
+	struct kill_args ka;
+
+	SCARG(&ka, pid) = SCARG(uap, pid);
+	SCARG(&ka, signum) = SVR4_SVR42BSD_SIG(SCARG(uap, signum));
+	return kill(p, &ka);
+}
+
+
+int 
+svr4_sys_context(p, uap)
+	register struct proc *p;
+	struct svr4_sys_context_args *uap;
+{
+	struct svr4_ucontext uc;
+	int error;
+
+	switch (uap->func) {
+	case 0:
+		DPRINTF(("getcontext(%p)\n", uap->uc));
+		svr4_getcontext(p, &uc, &p->p_sigmask,
+		    p->p_sigstk.ss_flags & SS_ONSTACK);
+		return copyout(&uc, uap->uc, sizeof(uc));
+
+	case 1: 
+		DPRINTF(("setcontext(%p)\n", uap->uc));
+		if ((error = copyin(uap->uc, &uc, sizeof(uc))) != 0)
+			return error;
+		DPRINTF(("uc_flags = %lx\n", uc.uc_flags));
+#if defined(DEBUG_SVR4)
+		{
+			int i;
+			for (i = 0; i < 4; i++)
+				DPRINTF(("uc_sigmask[%d] = %lx\n", i,
+							uc.uc_sigmask.bits[i]));
+		}
+#endif
+		return svr4_setcontext(p, &uc);
+
+	default:
+		DPRINTF(("context(%d, %p)\n", uap->func,
+		    uap->uc));
+		return ENOSYS;
+	}
+	return 0;
+}
+
+int
+svr4_sys_pause(p, uap)
+	register struct proc *p;
+	struct svr4_sys_pause_args *uap;
+{
+	struct sigsuspend_args bsa;
+
+	SCARG(&bsa, sigmask) = &p->p_sigmask;
+	return sigsuspend(p, &bsa);
+}