lib: add function set_bootcounter()

Function to reset the boot counter
Supporting old and new formats
Accept 2 arguments:
 bootcounter: number, 0 if skipped
 upgrade flag (could be omitted):
   1: set upgrade state (default)
   0: disable upgrade state

Signed-off-by: Denis Pynkin <denis.pynkin@collabora.com>

run-test-ota-rollback-blacklist.sh

@@ -19,11 +19,8 @@ phase_boot()
 	OLDREV=$(ostree rev-parse $BRANCHNAME)
 	ostree admin upgrade --allow-downgrade --deploy-only --override-commit=$OLDREV
 
-	# Emulate the ugrade state -- set the upgrade flag and bootcounter to 0
-	# Use old format to be compatible with the first implementation of the counter
-	# echo "bc 00" | xxd -r -p /boot/uboot.cnt
-	# New format (depending on U-Boot installed):
-	echo "bd 01 00 01" | xxd -r -p > /boot/uboot.cnt
+	# Emulate the ugrade state -- set  bootcounter to 0 and the upgrade flag
+	set_bootcounter 0 1
 
 	# Store the commit with prepared revision for use in tests later
 	echo $OLDREV > $(get_phase_data_path)
@@ -55,9 +52,7 @@ phase_check_update()
 
 	# Emulate the ugrade state -- set the upgrade flag and bootcounter to any value above the limit
 	# This should to trigger the U-Boot to boot previous version after reboot
-	# New format (depending on U-Boot installed):
-	echo "bd 01 05 01" | xxd -r -p > /boot/uboot.cnt
-	sync
+	set_bootcounter 5
 }
 
 phase_check_rollback()

run-test-rollback-blacklist.sh

@@ -47,9 +47,7 @@ phase_check_update()
 
 	# Emulate the ugrade state -- set the upgrade flag and bootcounter to any value above the limit
 	# This should to trigger the U-Boot to boot previous version after reboot
-	# New format (depending on U-Boot installed):
-	echo "bd 01 05 01" | xxd -r -p > /boot/uboot.cnt
-	sync
+	set_bootcounter 5
 }
 
 phase_check_rollback()

update-manager-common.sh

@@ -344,3 +344,38 @@ check_bootcounter()
 		return $ret
 	)
 }
+
+# Function to reset the boot counter
+# Supporting old and new formats
+# Accept 2 arguments:
+#  bootcounter: number, 0 if skip
+#  upgrade flag (could be omitted):
+#    1: set upgrade state (default)
+#    0: disable upgrade state
+set_bootcounter()
+{
+	local bootcount="${1:-0}"
+	local upgrade_flag="${2:-1}"
+
+	local magic="bc"
+	test -f /boot/uboot.cnt && magic="$(od -An -t x1 -N1 /boot/uboot.cnt | tr -d ' ')"
+
+	case "$magic" in
+		"bc")	# Old style "BC 00"
+			if [ "$upgrade_flag" -eq 1 ]; then
+				echo "bc $(printf "%.2x" $bootcount)" | xxd -r -p > /boot/uboot.cnt
+			else
+				# Remove the file to mark we are not in upgrade state
+				rm -f /boot/uboot.cnt
+			fi
+			;;
+		"bd")	# New style "BD 01 00 01"
+			echo "bd 01 $(printf "%.2x" $bootcount) $(printf "%.2x" $upgrade_flag)" | xxd -r -p > /boot/uboot.cnt
+			;;
+		*)
+			echo "Unknown magic ($magic) in /boot/uboot.cnt"
+			return 1
+			;;
+	esac
+	sync
+}