* It turns out that the people who told me that removing a conffile in the

  preinst was sufficient to have dpkg replace it without prompting when
  moving a conffile between packages were very much mistaken. As far as I
  can tell, the only way to do this reliably is to write out the desired
  new text of the conffile in the preinst. This is gross, and requires
  shipping the text of all conffiles in the preinst too, but there's
  nothing for it. Fortunately this nonsense is only required for smooth
  upgrades from sarge.

1 files changed, 19 insertions, 2 deletions

diff --git a/debian/openssh-client.preinst b/debian/openssh-client.preinst
index 0e200712e..9cf29dfba 100644
--- a/debian/openssh-client.preinst
+++ b/debian/openssh-client.preinst
@@ -1,17 +1,34 @@
 #! /bin/sh -e
 
+ETC_SSH_MODULI=@ETC_SSH_MODULI@
+
+ETC_SSH_SSH_CONFIG=@ETC_SSH_SSH_CONFIG@
+
 action="$1"
 version="$2"
 
 prepare_transfer_conffile () {
         CONFFILE="$1"
+        TEXT="$2"
+        MODE="$3"
         [ -e "$CONFFILE" ] || return 0
 
         md5sum="$(md5sum "$CONFFILE" |sed -e 's/ .*//')"
         old_md5sum="$(sed -n -e "/^Conffiles:/,/^[^ ]/{\\' $CONFFILE'{s/^ [^ ]* //;s/ .*//;p}}" /var/lib/dpkg/status)"
         if [ "$md5sum" = "$old_md5sum" ]; then
                 echo >&2 "Transferring ownership of conffile $CONFFILE ..."
+                # We have to write out the desired new text of the conffile,
+                # which is tricky in the preinst, hence the nasty way we
+                # have to hardcode the text here. Fortunately, this is only
+                # necessary with sarge's dpkg and older.
+                if echo "$TEXT" | head -n1 | grep -q '^@.*@$'; then
+                        echo >&2 'Unsubstituted conffile text! Please report this bug.'
+                        exit 1
+                fi
+                printf '%s' "$TEXT" >"$CONFFILE.dpkg-new"
+                chmod "$MODE" "$CONFFILE.dpkg-new"
                 mv -f "$CONFFILE" "$CONFFILE.moved-by-preinst"
+                mv -f "$CONFFILE.dpkg-new" "$CONFFILE"
                 return 0
         fi
 }
@@ -19,8 +36,8 @@ prepare_transfer_conffile () {
 case $action in
         install|upgrade)
                 if dpkg --compare-versions "$version" lt 0; then
-                        prepare_transfer_conffile /etc/ssh/moduli
-                        prepare_transfer_conffile /etc/ssh/ssh_config
+                        prepare_transfer_conffile /etc/ssh/moduli "$ETC_SSH_MODULI" 0644
+                        prepare_transfer_conffile /etc/ssh/ssh_config "$ETC_SSH_SSH_CONFIG" 0644
                 fi
                 ;;
 esac