From f49d8202560a777f033de1f50d0b3372c5a12fe7 Mon Sep 17 00:00:00 2001
From: Konstantin Belousov <kib@FreeBSD.org>
Date: Tue, 12 Jul 2011 20:37:18 +0000
Subject: [PATCH] Implement an RFTSIGZMB flag to rfork(2) to specify a signal
 that is delivered to parent when the child exists.

Submitted by:	Petr Salinger <Petr.Salinger seznam cz> (Debian/kFreeBSD)
MFC after:	1 week
X-MFC-note:	bump __FreeBSD_version
---
 sys/kern/kern_fork.c | 17 ++++++++++++++++-
 sys/sys/unistd.h     |  8 ++++++++
 2 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/sys/kern/kern_fork.c b/sys/kern/kern_fork.c
index a8abd8e86c83..9d3e22d224cf 100644
--- a/sys/kern/kern_fork.c
+++ b/sys/kern/kern_fork.c
@@ -476,7 +476,10 @@ do_fork(struct thread *td, int flags, struct proc *p2, struct thread *td2,
 		sigacts_copy(newsigacts, p1->p_sigacts);
 		p2->p_sigacts = newsigacts;
 	}
-	if (flags & RFLINUXTHPN) 
+
+	if (flags & RFTSIGZMB)
+	        p2->p_sigparent = RFTSIGNUM(flags);
+	else if (flags & RFLINUXTHPN)
 	        p2->p_sigparent = SIGUSR1;
 	else
 	        p2->p_sigparent = SIGCHLD;
@@ -719,10 +722,22 @@ fork1(struct thread *td, int flags, int pages, struct proc **procp)
 	static int curfail;
 	static struct timeval lastfail;
 
+	/* Check for the undefined or unimplemented flags. */
+	if ((flags & ~(RFFLAGS | RFTSIGFLAGS(RFTSIGMASK))) != 0)
+		return (EINVAL);
+
+	/* Signal value requires RFTSIGZMB. */
+	if ((flags & RFTSIGFLAGS(RFTSIGMASK)) != 0 && (flags & RFTSIGZMB) == 0)
+		return (EINVAL);
+
 	/* Can't copy and clear. */
 	if ((flags & (RFFDG|RFCFDG)) == (RFFDG|RFCFDG))
 		return (EINVAL);
 
+	/* Check the validity of the signal number. */
+	if ((flags & RFTSIGZMB) != 0 && (u_int)RFTSIGNUM(flags) > _SIG_MAXSIG)
+		return (EINVAL);
+
 	p1 = td->td_proc;
 
 	/*
diff --git a/sys/sys/unistd.h b/sys/sys/unistd.h
index 378308de8204..9d56a3a42730 100644
--- a/sys/sys/unistd.h
+++ b/sys/sys/unistd.h
@@ -180,8 +180,16 @@
 #define	RFLINUXTHPN	(1<<16)	/* do linux clone exit parent notification */
 #define	RFSTOPPED	(1<<17)	/* leave child in a stopped state */
 #define	RFHIGHPID	(1<<18)	/* use a pid higher than 10 (idleproc) */
+#define	RFTSIGZMB	(1<<19)	/* select signal for exit parent notification */
+#define	RFTSIGSHIFT	20	/* selected signal number is in bits 20-27  */
+#define	RFTSIGMASK	0xFF
+#define	RFTSIGNUM(flags)	(((flags) >> RFTSIGSHIFT) & RFTSIGMASK)
+#define	RFTSIGFLAGS(signum)	((signum) << RFTSIGSHIFT)
 #define	RFPPWAIT	(1<<31)	/* parent sleeps until child exits (vfork) */
 #define	RFKERNELONLY	(RFSTOPPED | RFHIGHPID | RFPPWAIT)
+#define	RFFLAGS		(RFFDG | RFPROC | RFMEM | RFNOWAIT | RFCFDG | \
+    RFTHREAD | RFSIGSHARE | RFLINUXTHPN | RFSTOPPED | RFHIGHPID | RFTSIGZMB | \
+    RFPPWAIT)
 
 #endif /* __BSD_VISIBLE */