use ifup for bridge-less cable; allow UPPER scripting for image file root; allow no-overlay subhost

functions

@@ -50,57 +50,86 @@ auto eth$i
 iface eth$i inet manual
 EOF
 	BR="${C%=*}"
-	[ -z "$BR" ] || brctl addif $BR $IF
+	if [ -z "$BR" ] ; then
+	    ip link set $IF
+	    ifup $IF
+	else
+	    brctl addif $BR $IF
+	fi
 	i=$((i+1))
     done
 }
 
-REAPER=$(dirname $(realpath $0))/reaper
 # (name live system root work)
 # Set up an overlay fmr $name on $live, with a new tmpfs on its /run,
 # and "install" a "reaper" as the upcoming pid 1
 setup_overlay() {
-    local ROOT="$4"
-    local LIVE="$2"
+    local LIVE="$2" LOWER="$3" UPPER="$4" ROOT
 
     if grep -q "$1 $2" /proc/mounts ; then
 	die "$1 is already mounted"
     fi
 
-    # setup $ROOT/run
-    mkdir -p "$ROOT/run"
-    mount -t tmpfs -osize=100M tmpfs "$ROOT/run"
-    mkdir -p "$ROOT/run/lock"
-    # setup $ROOT/dev
-    mkdir -p "$ROOT/dev"
-    mount -t tmpfs -osize=100M tmpfs "$ROOT/dev"
-    mknod -m 622 "$ROOT/dev/console" c 5 1
-    mknod -m 666 "$ROOT/dev/null" c 1 3
-    mknod -m 666 "$ROOT/dev/zero" c 1 5
-    mknod -m 666 "$ROOT/dev/ptmx" c 5 2
-    mknod -m 666 "$ROOT/dev/tty" c 5 0
-    mknod -m 444 "$ROOT/dev/random" c 1 8
-    mknod -m 444 "$ROOT/dev/urandom" c 1 9
-    chown root:tty "$ROOT/dev/console"
-    chown root:tty "$ROOT/dev/ptmx"
-    chown root:tty "$ROOT/dev/tty"
-    ln -sTf /proc/self/fd "$ROOT/dev/fd"
-    ln -sTf /proc/self/fd/0 "$ROOT/dev/stdin"
-    ln -sTf /proc/self/fd/1 "$ROOT/dev/stdout"
-    ln -sTf /proc/self/fd/2 "$ROOT/dev/stderr"
-    ln -sTf /proc/kcore "$ROOT/dev/core"
-    mkdir "$ROOT/dev/shm"
-    mkdir "$ROOT/dev/pts"
-    chmod 1777 "$ROOT/dev/shm"
+    if [ -f "${UPPER%% *}" ] ; then
+	if [ -x "${UPPER%% *}" ] ; then
+	    echo "${UPPER%% *} appears to be executable" >&2
+	    # Giving a program/script as UPPER= asks for running this
+	    # first, to make a root filesystem available. The script takes
+	    # ACTION "setup" and "teardown", and on "setup" it must tell
+	    # where the ROOT is set up.
+	    ROOT="$(env ACTION=setup $UPPER)"
+	    if [ ! -d "$ROOT" ] ; then
+		# setup failed
+		die "root setup failed: $UPPER"
+	    fi
+	    UPPER="$ROOT"
+	    ## Now falling down to "normal overlay" setup
+	else
+	    die "${UPPER%% *} (root setup program/script) is not executable"
+	fi
+    fi
+
+    # LIVE is the same as LOWER then skip the overlay; just assume
+    # a proper chroot system exists at LIVE.
+    if [ "$LIVE" != "$LOWER" ] ; then
+	# setup $UPPER/run
+	mkdir -p "$UPPER/run"
+	mount -t tmpfs -osize=100M tmpfs "$UPPER/run"
+	mkdir -p "$UPPER/run/lock"
+	# setup $UPPER/dev
+	mkdir -p "$UPPER/dev"
+	mount -t tmpfs -osize=100M tmpfs "$UPPER/dev"
+	mknod -m 622 "$UPPER/dev/console" c 5 1
+	mknod -m 666 "$UPPER/dev/null" c 1 3
+	mknod -m 666 "$UPPER/dev/zero" c 1 5
+	mknod -m 666 "$UPPER/dev/ptmx" c 5 2
+	mknod -m 666 "$UPPER/dev/tty" c 5 0
+	mknod -m 444 "$UPPER/dev/random" c 1 8
+	mknod -m 444 "$UPPER/dev/urandom" c 1 9
+	chown root:tty "$UPPER/dev/console"
+	chown root:tty "$UPPER/dev/ptmx"
+	chown root:tty "$UPPER/dev/tty"
+	ln -sTf /proc/self/fd "$UPPER/dev/fd"
+	ln -sTf /proc/self/fd/0 "$UPPER/dev/stdin"
+	ln -sTf /proc/self/fd/1 "$UPPER/dev/stdout"
+	ln -sTf /proc/self/fd/2 "$UPPER/dev/stderr"
+	ln -sTf /proc/kcore "$UPPER/dev/core"
+	mkdir "$UPPER/dev/shm"
+	mkdir "$UPPER/dev/pts"
+	chmod 1777 "$UPPER/dev/shm"
 
-    if mount -t overlay -olowerdir=$3,upperdir=$4,workdir=$5 $1 $2 ; then
-	: # all good
-    else
-	umount -R "$ROOT/dev"
-	umount "$ROOT/run"
-	die "Cannot set up the overlay mount $2"
+	OLY="-olowerdir=$3,upperdir=$UPPER,workdir=$5"
+	if mount -t overlay "$OLY" $1 $2 ; then
+	    : # all good
+	else
+	    umount -R "$UPPER/dev"
+	    umount "$UPPER/run"
+	    die "Cannot set up the overlay mount $2"
+	fi
     fi
-    cp -p $REAPER $LIVE/.reaper
+
+    echo "Installing $OVERLAYDIR/reaper to $LIVE/.reaper"
+    cp -p $OVERLAYDIR/reaper $LIVE/.reaper
 }
 
 start_services() {

overlay-boot

@@ -4,10 +4,14 @@
 # is an overlay of the subhost's root and an OS root. The service
 # subhost is defined by a configuration file named on teh command line
 
+OVERLAYDIR="$(realpath $(dirname $0))"
+
 [ $(id -u) = 0 ] || exec sudo $0 $@
 . $(dirname $(realpath $0))/functions $*
+
 CONFIG="$1"
 [ -r "$CONFIG" ] || die "Missing configuration $CONFIG"
+
 config NAME $(basename $1 .${1##*.})
 config LOG /tmp/oly-$NAME.log
 
@@ -28,6 +32,10 @@ fi
 config BASE
 BASE="$(cd $(dirname $CONFIG); realpath $BASE)"
 
+[ -z "$BASE" ] && die "BASE is unset; bogus $CONFIG ?"
+[ -d "$BASE" ] || die "$BASE is not a directory; bogus $CONFIG ?"
+cd "$BASE" || die "$BASE is inaccessible"
+
 config LIVE "$BASE/live"
 config UPPER "$BASE/root"
 config WORK "$BASE/work"
@@ -45,19 +53,35 @@ setup_overlay "$NAME" "$LIVE" "$LOWER" "$UPPER" "$WORK"
 
 exithandler() {
     ip netns del $NAME
-    umount -R "$LIVE"
+    [ "$LOWER" != "$LIVE" ] && umount -R "$LIVE"
+    [ -f "${UPPER%% *}" ] && [ -x "${UPPER%% *}" ] && \
+	env ACTION=teardown $UPPER
 }
 trap "exithandler" 0
 
 CMD="unshare -fp --mount-proc ip netns exec $NAME chroot $LIVE /bin/sh"
 echo "$CMD"
 
+config RAM_SIZE 50M
+
 cat <<EOF | $CMD
 set -x
 mount -t proc proc /proc
 mount -t devpts devpts /dev/pts
 mount -t sysfs sysfs /sys
+if [ "$RAM_SIZE" != "none" ] && ! grep -q '/run tmpfs' /proc/mounts ; then
+    mount -t tmpfs -osize=$RAM_SIZE,mode=755 tmpfs /run
+fi
 for srv in $START ; do service \$srv start ; done
+dummy_service() {
+    [ \$# -gt 3 ] && return 0
+    echo "Starting dummy service" >&2
+    set +x
+    [ -p /run/dummy_service ] || mkfifo /run/dummy_service
+    ( printf dummy_service > /proc/self/comm ; read X < /run/dummy_service ) &
+    set -x
+}
+dummy_service /proc/*/comm
 exec /.reaper $NAME
 EOF
 echo "EXITED $CMD"

overlay-go

@@ -25,3 +25,9 @@ EOF
 fi
 
 sudo nsenter -t "$RSPID" -n -m -p -r -w -u -C /bin/bash
+if [ $? = 137 ] ; then
+    echo "######### please 'fg' this again (if stopped)" >&2
+    stty sane # a killed bash might leave the tty insane and stty
+              # typically gets stopped trying to correct it
+fi
+echo "done"