xpp: waitfor_xpds: handle missing serial numbers

Fixes a regression since 949ea4ca9f
(2.7.0) - allows using an Astribank with no serial.

* Some of the olderst Astribanks don't have a serial number burned in
  them. Thus there is no serial attribute for the sysfs USB device node.

* waitfor_xpds identifies the Astribanks by their serial numbers.

* An lone Astribank without serial number would thus block waitfor_xpds
  (until timeout).

* Now we warn about them.

* We also try to handle it gracefully. As long as there's only one
  of thease, it would be counted as "NO-SERIAL".

Signed-off-by: Tzafrir Cohen <tzafrir.cohen@xorcom.com>

xpp/waitfor_xpds

@@ -41,18 +41,25 @@ ab_list() {
 }
 
 ab_serial_nums() {
-	ab_list | \
-		sed 's,$,/serial,' | \
-		xargs grep -H '' 2>/dev/null | \
-		sed 's,.*/serial:,,' | \
-		sed 's/^$/NO-SERIAL/' | \
-		sort -u
+	for i in `ab_list`; do
+		s=`cat "$i/serial" 2>/dev/null` || :
+		if [ "$s" = '' ]; then
+			echo "NO-SERIAL"
+		else
+			echo "$s"
+		fi
+	done | sort -u || :
 }
 
 detected_serial_nums() {
-	cat /sys/bus/astribanks/devices/*/transport/serial 2> /dev/null | \
-		sed 's/^$/NO-SERIAL/' | \
-		sort -u || :
+	for i in /sys/bus/astribanks/devices/*/transport; do
+		s=`cat "$i/serial" 2>/dev/null` || :
+		if [ "$s" = '' ]; then
+			echo "NO-SERIAL"
+		else
+			echo "$s"
+		fi
+	done | sort -u || :
 }
 
 calc_union() {
@@ -98,6 +105,14 @@ if ! astribank_is_starting; then
 	exit 0
 fi
 
+# Sanity check
+for i in `ab_list`; do
+	s=`cat "$i/serial" 2>/dev/null` || :
+	if [ "$s" = '' ]; then
+		echo >&2 "WARNING! Astribank without serial number: $i"
+	fi
+done
+
 serial_nums=`ab_serial_nums`
 
 # Loop until detected (hopefully) all astribanks and they are initialized