Backend: update apex support

- support unmounting TWRP's mounted apex files to avoid conflicts
- hide less apex u/mount stderr to aid future debugging

META-INF/com/google/android/update-binary

@@ -69,8 +69,8 @@ mount_apex() {
         if [ $? != 0 ]; then
           while [ $num -lt 64 ]; do
             loop=/dev/block/loop$num;
-            ($BB mknod $loop b 7 $((num * minorx));
-            $BB losetup $loop $dest.img) 2>/dev/null;
+            [ -e $loop ] || $BB mknod $loop b 7 $((num * minorx));
+            $BB losetup $loop $dest.img 2>/dev/null;
             num=$((num + 1));
             $BB losetup $loop | $BB grep -q $dest.img && break;
           done;
@@ -89,9 +89,8 @@ mount_apex() {
   $($BB grep -o 'export .* /.*' /system_root/init.environ.rc | $BB sed 's; /;=/;'); unset export;
 }
 umount_apex() {
-  [ -d /apex/com.android.runtime ] || return 1;
   local dest loop var;
-  for var in $($BB grep -o 'export .* /.*' /system_root/init.environ.rc | $BB awk '{ print $2 }'); do
+  for var in $($BB grep -o 'export .* /.*' /system_root/init.environ.rc 2>/dev/null | $BB awk '{ print $2 }'); do
     if [ "$(eval echo \$OLD_$var)" ]; then
       eval $var=\$OLD_${var};
     else
@@ -100,11 +99,9 @@ umount_apex() {
     unset OLD_${var};
   done;
   for dest in $($BB find /apex -type d -mindepth 1 -maxdepth 1); do
-    if [ -f $dest.img ]; then
-      loop=$($BB mount | $BB grep $dest | $BB cut -d\  -f1);
-    fi;
-    ($BB umount -l $dest;
-    $BB losetup -d $loop) 2>/dev/null;
+    loop=$($BB mount | $BB grep $dest | $BB grep loop | $BB cut -d\  -f1);
+    $BB umount -l $dest;
+    [ "$loop" ] && $BB losetup -d $loop;
   done;
   $BB rm -rf /apex 2>/dev/null;
 }

META-INF/com/google/android/updater-script

@@ -3,4 +3,4 @@
 # Dummy file; update-binary is a shell script (DO NOT CHANGE)
 #
 #
-# AK_BASE_VERSION=20211004
+# AK_BASE_VERSION=20211016