debian/postinst: add checks, be verbose

Do not attempt to change permissions/ownership if the package gets
upgraded from a version higher than the next release.

Do not fail if the user deleted the config file.

Be verbose when changing permissions.

Related: OS#4107
Change-Id: I48e8f5d2a36886d28366bef1918f7464a48d2159
---
M debian/postinst
1 file changed, 21 insertions(+), 2 deletions(-)

diff --git a/debian/postinst b/debian/postinst
index 680cb2f..3353c37 100755
--- a/debian/postinst
+++ b/debian/postinst
@@ -16,8 +16,10 @@
 		fi
 
 		# Fix permissions of previous (root-owned) install (OS#4107)
-		mkdir -p /var/lib/osmo_dia2gsup
-		chown -R osmocom:osmocom /var/lib/osmo_dia2gsup
+		if dpkg --compare-versions "$2" le "0.3.0"; then
+			mkdir -p /var/lib/osmo_dia2gsup
+			chown -R -v osmocom:osmocom /var/lib/osmo_dia2gsup
+		fi
 		;;
 esac
 

