Change default privsep directory to /var/empty.

Add a post-install check to ensure that PRIVSEP_PATH is really empty.

INSTALL

@@ -57,11 +57,20 @@ for creating the user and group are system dependant):
 On most Linux and BSD systems, something like should work:
 
  groupadd _ntp
- useradd -g _ntp -s /sbin/nologin -d /var/empty/ntp -c 'OpenNTP daemon' _ntp
- mkdir -p /var/empty/ntp
- chown 0 /var/empty/ntp
- chgrp 0 /var/empty/ntp
- chmod 0755 /var/empty/ntp
+ useradd -g _ntp -s /sbin/nologin -d /var/empty -c 'OpenNTP daemon' _ntp
+ mkdir -p /var/empty
+ chown 0 /var/empty
+ chgrp 0 /var/empty
+ chmod 0755 /var/empty
+
+NOTE:
+If you installed a previous OpenNTPD release and created a /var/empty/ntp
+directory, please delete the /var/empty/ntp directory and adjust the _ntp
+user's home directory to point to /var/empty instead.
+
+This is important because, if you have any other daemons that also use
+/var/empty as a home directory, they will all have an empty privilege
+separation directory.
 
 As of OS X 10.10, something this this should work similarly
 (thanks to jasper@ for suggesting)

Makefile.am

@@ -66,7 +66,8 @@ install-exec-hook:
 	@if [ ! -f "$(DESTDIR)$(sysconfdir)/ntpd.conf" ]; then \
 		$(INSTALL) -m 644 "$(srcdir)/ntpd.conf" "$(DESTDIR)$(sysconfdir)/ntpd.conf"; \
 	else \
-		echo "$(DESTDIR)$(sysconfdir)/ntpd.conf already exists, install will not overwrite"; \
+		echo; \
+		echo " $(DESTDIR)$(sysconfdir)/ntpd.conf already exists, install will not overwrite"; \
 	fi
 	@if [ ! -d "$(PRIVSEP_PATH)" ]; then \
 		echo; \
@@ -100,6 +101,17 @@ install-exec-hook:
 		echo ; \
 		echo "   useradd -g $(PRIVSEP_USER) -s /sbin/nologin -d $(PRIVSEP_PATH) -c 'OpenNTP daemon' $(PRIVSEP_USER)" ; \
 	fi
+	@if [ -d $(PRIVSEP_PATH) ]; then \
+		if [ `ls -A $(PRIVSEP_PATH)|wc -l` != "0" ]; then \
+		echo; \
+		echo " WARNING: the privilege separation path is specified as $(PRIVSEP_PATH), " ; \
+		echo "          but this directory contains files!" ; \
+		echo ; \
+		echo " Please ensure that $(PRIVSEP_PATH) is empty. If you installed a previous " ; \
+		echo " OpenNTPD version and created a user with a home directory at /var/empty/ntpd, " ; \
+		echo " please adjust that user to use /var/empty instead and delete /var/empty/ntpd." ; \
+		fi; \
+	fi
 	@echo
 
 uninstall-local:

configure.ac

@@ -204,7 +204,7 @@ AC_ARG_WITH(privsep-path,
 	[ AC_DEFINE_UNQUOTED(NTPD_CHROOT_DIR, "$withval",
 	    [Privilege separation chroot path])
 	  PRIVSEP_PATH=$withval ],
-	[ PRIVSEP_PATH=/var/empty/ntp ]
+	[ PRIVSEP_PATH=/var/empty ]
 )
 AC_SUBST(PRIVSEP_PATH)