package/dropbear: Fix symlink only if pointing to the right directory

This commit ensures that the /etc/dropbear symlink won't be removed if
it points elsewhere than /var/run/dropbear.

[Thomas:
 - fix indentation / too long lines as suggested by Yann E. Morin.]

Signed-off-by: Paul Cercueil <paul@crapouillou.net>
Reviewed-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/dropbear/S50dropbear

@@ -12,12 +12,14 @@ start() {
 	echo -n "Starting dropbear sshd: "
 	umask 077
 
-	# If /etc/dropbear is not a directory, and
+	# If /etc/dropbear is a symlink to /var/run/dropbear, and
 	#   - the filesystem is RO (i.e. we can not rm the symlink),
 	#     create the directory pointed to by the symlink.
 	#   - the filesystem is RW (i.e. we can rm the symlink),
 	#     replace the symlink with an actual directory
-	if ! [ -d /etc/dropbear ]; then
+	if [ -L /etc/dropbear \
+	     -a "$(readlink -f /etc/dropbear)" = "/var/run/dropbear" ]
+	then
 		if rm -f /etc/dropbear; then
 			mkdir -p /etc/dropbear
 		else

package/dropbear/dropbear.service

@@ -3,13 +3,14 @@ Description=Dropbear SSH daemon
 After=syslog.target network.target auditd.service
 
 [Service]
-# If /etc/dropbear is not a directory, and
+# If /etc/dropbear is a symlink to /var/run/dropbear, and
 #   - the filesystem is RO (i.e. we can not rm the symlink),
 #     create the directory pointed to by the symlink.
 #   - the filesystem is RW (i.e. we can rm the symlink),
 #     replace the symlink with an actual directory
 ExecStartPre=/bin/sh -c '\
-if ! [ -d /etc/dropbear ]; then \
+if [ -L /etc/dropbear \
+     -a "$(readlink -f /etc/dropbear)" = "/var/run/dropbear" ]; then \
     if rm -f /etc/dropbear; then \
         mkdir -p /etc/dropbear; \
     else \