Split 4.x and 5.x signal handling so that we can keep 4.x signal

handling clean and functional as 5.x evolves.  This allows some of the
nasty bandaids in the 5.x codepaths to be unwound.

Encapsulate 4.x signal handling under COMPAT_FREEBSD4 (there is an
anti-foot-shooting measure in place, 5.x folks need this for a while) and
finish encapsulating the older stuff under COMPAT_43.  Since the ancient
stuff is required on alpha (longjmp(3) passes a 'struct osigcontext *'
to the current sigreturn(2), instead of the 'ucontext_t *' that sigreturn
is supposed to take), add a compile time check to prevent foot shooting
there too.  Add uniform COMPAT_43 stubs for ia64/sparc64/powerpc.

Tested on: i386, alpha, ia64.  Compiled on sparc64 (a few days ago).
Approved by: re

4 files changed, 89 insertions, 19 deletions

diff --git a/sys/kern/init_sysent.c b/sys/kern/init_sysent.c
index fb28d32..601920b 100644
--- a/sys/kern/init_sysent.c
+++ b/sys/kern/init_sysent.c
@@ -131,7 +131,7 @@ struct sysent sysent[] = {
 	{ SYF_MPSAFE | AS(getpriority_args), (sy_call_t *)getpriority },	/* 100 = getpriority */
 	{ compat(SYF_MPSAFE | AS(osend_args),send) },	/* 101 = old send */
 	{ compat(SYF_MPSAFE | AS(orecv_args),recv) },	/* 102 = old recv */
-	{ SYF_MPSAFE | AS(osigreturn_args), (sy_call_t *)osigreturn },	/* 103 = osigreturn */
+	{ compat(SYF_MPSAFE | AS(osigreturn_args),sigreturn) },	/* 103 = old sigreturn */
 	{ SYF_MPSAFE | AS(bind_args), (sy_call_t *)bind },	/* 104 = bind */
 	{ SYF_MPSAFE | AS(setsockopt_args), (sy_call_t *)setsockopt },	/* 105 = setsockopt */
 	{ SYF_MPSAFE | AS(listen_args), (sy_call_t *)listen },	/* 106 = listen */
@@ -370,9 +370,9 @@ struct sysent sysent[] = {
 	{ 0, (sy_call_t *)nosys },			/* 339 = pioctl */
 	{ SYF_MPSAFE | AS(sigprocmask_args), (sy_call_t *)sigprocmask },	/* 340 = sigprocmask */
 	{ SYF_MPSAFE | AS(sigsuspend_args), (sy_call_t *)sigsuspend },	/* 341 = sigsuspend */
-	{ SYF_MPSAFE | AS(sigaction_args), (sy_call_t *)sigaction },	/* 342 = sigaction */
+	{ compat4(SYF_MPSAFE | AS(freebsd4_sigaction_args),sigaction) },	/* 342 = old sigaction */
 	{ SYF_MPSAFE | AS(sigpending_args), (sy_call_t *)sigpending },	/* 343 = sigpending */
-	{ SYF_MPSAFE | AS(sigreturn_args), (sy_call_t *)sigreturn },	/* 344 = sigreturn */
+	{ compat4(SYF_MPSAFE | AS(freebsd4_sigreturn_args),sigreturn) },	/* 344 = old sigreturn */
 	{ 0, (sy_call_t *)nosys },			/* 345 = sigtimedwait */
 	{ 0, (sy_call_t *)nosys },			/* 346 = sigwaitinfo */
 	{ SYF_MPSAFE | AS(__acl_get_file_args), (sy_call_t *)__acl_get_file },	/* 347 = __acl_get_file */
@@ -444,8 +444,8 @@ struct sysent sysent[] = {
 	{ AS(extattr_get_link_args), (sy_call_t *)extattr_get_link },	/* 413 = extattr_get_link */
 	{ AS(extattr_delete_link_args), (sy_call_t *)extattr_delete_link },	/* 414 = extattr_delete_link */
 	{ 0, (sy_call_t *)nosys },			/* 415 = __execve_mac */
-	{ 0, (sy_call_t *)nosys },			/* 416 = newsigreturn */
-	{ 0, (sy_call_t *)nosys },			/* 417 = newsigaction */
+	{ SYF_MPSAFE | AS(sigaction_args), (sy_call_t *)sigaction },	/* 416 = sigaction */
+	{ SYF_MPSAFE | AS(sigreturn_args), (sy_call_t *)sigreturn },	/* 417 = sigreturn */
 	{ 0, (sy_call_t *)nosys },			/* 418 = __xstat */
 	{ 0, (sy_call_t *)nosys },			/* 419 = __xfstat */
 	{ 0, (sy_call_t *)nosys },			/* 420 = __xlstat */
diff --git a/sys/kern/kern_sig.c b/sys/kern/kern_sig.c
index 0d5000e..3503609 100644
--- a/sys/kern/kern_sig.c
+++ b/sys/kern/kern_sig.c
@@ -73,6 +73,13 @@
 
 #include <machine/cpu.h>
 
+#if !defined(COMPAT_FREEBSD4) && !defined(NO_COMPAT_FREEBSD4)
+#error "You *really* want COMPAT_FREEBSD4 on -current for a while"
+#endif
+#if defined (__alpha__) && !defined(COMPAT_43)
+#error "You *really* need COMPAT_43 on the alpha for longjmp(3)"
+#endif
+
 #define	ONSIG	32		/* NSIG for osig* syscalls.  XXX. */
 
 static int	coredump(struct thread *);
@@ -229,14 +236,15 @@ sig_ffs(sigset_t *set)
 /*
  * kern_sigaction
  * sigaction
+ * freebsd4_sigaction
  * osigaction
  */
 int
-kern_sigaction(td, sig, act, oact, old)
+kern_sigaction(td, sig, act, oact, flags)
 	struct thread *td;
 	register int sig;
 	struct sigaction *act, *oact;
-	int old;
+	int flags;
 {
 	register struct sigacts *ps;
 	struct proc *p = td->td_proc;
@@ -353,9 +361,18 @@ kern_sigaction(td, sig, act, oact, old)
 			else
 				SIGADDSET(p->p_sigcatch, sig);
 		}
+#ifdef COMPAT_FREEBSD4
+		if (ps->ps_sigact[_SIG_IDX(sig)] == SIG_IGN ||
+		    ps->ps_sigact[_SIG_IDX(sig)] == SIG_DFL ||
+		    (flags & KSA_FREEBSD4) == 0)
+			SIGDELSET(ps->ps_freebsd4, sig);
+		else
+			SIGADDSET(ps->ps_freebsd4, sig);
+#endif
 #ifdef COMPAT_43
 		if (ps->ps_sigact[_SIG_IDX(sig)] == SIG_IGN ||
-		    ps->ps_sigact[_SIG_IDX(sig)] == SIG_DFL || !old)
+		    ps->ps_sigact[_SIG_IDX(sig)] == SIG_DFL ||
+		    (flags & KSA_OSIGSET) == 0)
 			SIGDELSET(ps->ps_osigset, sig);
 		else
 			SIGADDSET(ps->ps_osigset, sig);
@@ -403,6 +420,46 @@ done2:
 	return (error);
 }
 
+#ifdef COMPAT_FREEBSD4
+#ifndef _SYS_SYSPROTO_H_
+struct freebsd4_sigaction_args {
+	int	sig;
+	struct	sigaction *act;
+	struct	sigaction *oact;
+};
+#endif
+/*
+ * MPSAFE
+ */
+/* ARGSUSED */
+int
+freebsd4_sigaction(td, uap)
+	struct thread *td;
+	register struct freebsd4_sigaction_args *uap;
+{
+	struct sigaction act, oact;
+	register struct sigaction *actp, *oactp;
+	int error;
+
+	mtx_lock(&Giant);
+
+	actp = (uap->act != NULL) ? &act : NULL;
+	oactp = (uap->oact != NULL) ? &oact : NULL;
+	if (actp) {
+		error = copyin(uap->act, actp, sizeof(act));
+		if (error)
+			goto done2;
+	}
+	error = kern_sigaction(td, uap->sig, actp, oactp, KSA_FREEBSD4);
+	if (oactp && !error) {
+		error = copyout(oactp, uap->oact, sizeof(oact));
+	}
+done2:
+	mtx_unlock(&Giant);
+	return (error);
+}
+#endif	/* COMAPT_FREEBSD4 */
+
 #ifdef COMPAT_43	/* XXX - COMPAT_FBSD3 */
 #ifndef _SYS_SYSPROTO_H_
 struct osigaction_args {
@@ -441,7 +498,7 @@ osigaction(td, uap)
 		nsap->sa_flags = sa.sa_flags;
 		OSIG2SIG(sa.sa_mask, nsap->sa_mask);
 	}
-	error = kern_sigaction(td, uap->signum, nsap, osap, 1);
+	error = kern_sigaction(td, uap->signum, nsap, osap, KSA_OSIGSET);
 	if (osap && !error) {
 		sa.sa_handler = osap->sa_handler;
 		sa.sa_flags = osap->sa_flags;
@@ -452,6 +509,18 @@ done2:
 	mtx_unlock(&Giant);
 	return (error);
 }
+
+#if !defined(__i386__) && !defined(__alpha__)
+/* Avoid replicating the same stub everywhere */
+int
+osigreturn(td, uap)
+	struct thread *td;
+	struct osigreturn_args *uap;
+{
+
+	return (nosys(td, (struct nosys_args *)uap));
+}
+#endif
 #endif /* COMPAT_43 */
 
 /*
diff --git a/sys/kern/syscalls.c b/sys/kern/syscalls.c
index 142e8f2..3215b63 100644
--- a/sys/kern/syscalls.c
+++ b/sys/kern/syscalls.c
@@ -110,7 +110,7 @@ char *syscallnames[] = {
 	"getpriority",			/* 100 = getpriority */
 	"old.send",		/* 101 = old send */
 	"old.recv",		/* 102 = old recv */
-	"osigreturn",			/* 103 = osigreturn */
+	"old.sigreturn",		/* 103 = old sigreturn */
 	"bind",			/* 104 = bind */
 	"setsockopt",			/* 105 = setsockopt */
 	"listen",			/* 106 = listen */
@@ -349,9 +349,9 @@ char *syscallnames[] = {
 	"#339",			/* 339 = pioctl */
 	"sigprocmask",			/* 340 = sigprocmask */
 	"sigsuspend",			/* 341 = sigsuspend */
-	"sigaction",			/* 342 = sigaction */
+	"old.sigaction",		/* 342 = old sigaction */
 	"sigpending",			/* 343 = sigpending */
-	"sigreturn",			/* 344 = sigreturn */
+	"old.sigreturn",		/* 344 = old sigreturn */
 	"#345",			/* 345 = sigtimedwait */
 	"#346",			/* 346 = sigwaitinfo */
 	"__acl_get_file",			/* 347 = __acl_get_file */
@@ -423,8 +423,8 @@ char *syscallnames[] = {
 	"extattr_get_link",			/* 413 = extattr_get_link */
 	"extattr_delete_link",			/* 414 = extattr_delete_link */
 	"#415",			/* 415 = __execve_mac */
-	"#416",			/* 416 = newsigreturn */
-	"#417",			/* 417 = newsigaction */
+	"sigaction",			/* 416 = sigaction */
+	"sigreturn",			/* 417 = sigreturn */
 	"#418",			/* 418 = __xstat */
 	"#419",			/* 419 = __xfstat */
 	"#420",			/* 420 = __xlstat */
diff --git a/sys/kern/syscalls.master b/sys/kern/syscalls.master
index a0172b8..482b2a9 100644
--- a/sys/kern/syscalls.master
+++ b/sys/kern/syscalls.master
@@ -175,7 +175,7 @@
 100	MSTD	BSD	{ int getpriority(int which, int who); }
 101	MCOMPAT	BSD	{ int send(int s, caddr_t buf, int len, int flags); }
 102	MCOMPAT	BSD	{ int recv(int s, caddr_t buf, int len, int flags); }
-103	MSTD	BSD	{ int osigreturn(struct osigcontext *sigcntxp); }
+103	MCOMPAT	BSD	{ int sigreturn(struct osigcontext *sigcntxp); }
 104	MSTD	BSD	{ int bind(int s, caddr_t name, int namelen); }
 105	MSTD	BSD	{ int setsockopt(int s, int level, int name, \
 			    caddr_t val, int valsize); }
@@ -490,10 +490,10 @@
 340	MSTD	POSIX	{ int sigprocmask(int how, const sigset_t *set, \
 			    sigset_t *oset); }
 341	MSTD	POSIX	{ int sigsuspend(const sigset_t *sigmask); }
-342	MSTD	POSIX	{ int sigaction(int sig, const struct sigaction *act, \
+342	MCOMPAT4 POSIX	{ int sigaction(int sig, const struct sigaction *act, \
 			    struct sigaction *oact); }
 343	MSTD	POSIX	{ int sigpending(sigset_t *set); }
-344	MSTD	BSD	{ int sigreturn(const struct __ucontext *sigcntxp); }
+344	MCOMPAT4 BSD	{ int sigreturn(const struct ucontext4 *sigcntxp); }
 345	UNIMPL	NOHIDE	sigtimedwait
 346	UNIMPL	NOHIDE	sigwaitinfo
 347	MSTD	BSD	{ int __acl_get_file(const char *path, \
@@ -601,8 +601,9 @@
 414	STD	BSD	{ int extattr_delete_link(const char *path, \
 			    int attrnamespace, const char *attrname); }
 415	UNIMPL	BSD	__execve_mac
-416	UNIMPL	BSD	newsigreturn
-417	UNIMPL	BSD	newsigaction
+416	MSTD	POSIX	{ int sigaction(int sig, const struct sigaction *act, \
+			    struct sigaction *oact); }
+417	MSTD	BSD	{ int sigreturn(const struct __ucontext *sigcntxp); }
 418	UNIMPL	BSD	__xstat
 419	UNIMPL	BSD	__xfstat
 420	UNIMPL	BSD	__xlstat