[Logcheck-devel] Bug#453519: logcheck-database: amavisd-new file looks like the one shipped by amavisd-new

[Frédéric Brière]

On Sat, Aug 22, 2009 at 11:21:35AM -0400, Frédéric Brière wrote:
> There's no way to tell this manually-added file apart from another one
> which was left around as cruft.

Actually, this doesn't bother dpkg at all, which will gladly convert
such a file into a conffile when the occasion comes.  If it's good
enough for dpkg, it's good enough for me.

So, here's the commit I made to remove old crufty files.  I tested it as
much as possible, but a little peer review certainly wouldn't hurt.


commit 7c0a9db4606434b8366b64f82b31f428228a9237
Author: Frédéric Brière <fbriere at fbriere.net>
Date:   Sun Aug 23 16:24:37 2009 -0400

    Support removing even older conffiles in logcheck-database's preinst
    
    Many conffiles have come and gone throughout logcheck's history, and due
    to the fact that dpkg did not remove them, these obsolete files are
    still left rotting on many installations.  (See bug #453519 for an
    example.)
    
    This attempts to delete those files on install/upgrade, after making
    sure they have not been "adopted" by another package in the meantime.
    If a file is deemed to have been modified, it will be backed up and
    subsequently ignored by logcheck.
    
    Since there may no longer be any record of that conffile[*], a list of
    past MD5 checksums must be provided in $OLD_CONFFILES.  More than one
    checksum is allowed per conffile, as the package may have been upgraded
    past the last modification, leaving the conffile in an older state.
    
    Unlike with rm_conffile(), we do bother comparing package versions here,
    as the call to dpkg-query --search can be costly.  One single version
    check should be enough, as we don't plan (with any luck) to add any
    files to that list.
    
    [*] Actually, dpkg will keep a record of that conffile up until the
    package is purged, or another package adopts it.

diff --git a/debian/logcheck-database.preinst b/debian/logcheck-database.preinst
index c2d6589..a7e3eca 100644
--- a/debian/logcheck-database.preinst
+++ b/debian/logcheck-database.preinst
@@ -18,10 +18,22 @@ set -e
 # deleted (or backed away) at the next upgrade.
 #
 # Conffiles must be listed here from the very moment of their removal; adding
-# them later on will not work correctly.
+# them later on will not work correctly.  If you ever forget, you'll need to
+# add them to OLD_CONFFILES below, instead.
 
 REMOVED_CONFFILES=""
 
+# List of conffiles which were once part of this package a long time ago, and
+# have never been cleaned up properly.  They will be removed if they are still
+# around, unclaimed, and match any specified MD5 checksum.
+#
+# Each line contains one filename, followed by one or many MD5 checksums, all
+# separated by whitespace.  When adding files to this list,
+# OLD_CONFFILES_VERSION needs to be bumped up to the current version.
+
+OLD_CONFFILES_VERSION="1.3.4"
+OLD_CONFFILES=""
+
 
 # Copied from <http://wiki.debian.org/DpkgConffileHandling>
 rm_conffile() {
@@ -46,6 +58,33 @@ rm_conffile() {
     fi
 }
 
+# Delete an old forgotten conffile if it's still around and unclaimed, and
+# matches one of any MD5 checksums.  If no checksum matches, it will be
+# backed up and move aside.
+rm_old_conffile() {
+    local PKGNAME="$1"
+    local CONFFILE="$2"
+    shift 2
+
+    [ -e "$CONFFILE" ] || return 0
+
+    # Leave that file alone if it now belongs to another package
+    dpkg-query --search "$CONFFILE" >/dev/null 2>&1 && return 0
+
+    local md5sum="$(md5sum $CONFFILE | sed -e 's/ .*//')"
+    for OLD_MD5SUM in "$@"; do
+        if [ "$md5sum" = "$OLD_MD5SUM" ]; then
+            echo "Removing obsolete conffile $CONFFILE ..."
+            rm -f "$CONFFILE"
+            return
+        fi
+    done
+
+    echo "Obsolete conffile $CONFFILE has been modified by you."
+    echo "Saving as $CONFFILE.dpkg-bak ..."
+    mv -f "$CONFFILE" "$CONFFILE".dpkg-bak
+}
+
 
 case "$1" in
     install|upgrade)
@@ -56,6 +95,21 @@ case "$1" in
                 rm_conffile logcheck-database "$CONFFILE"
             done
         fi
+
+        # Remove $OLD_CONFFILES on a new install, or when upgrading
+        # from an old version.
+        if dpkg --compare-versions "$2" lt "$OLD_CONFFILES_VERSION"; then
+            echo "$OLD_CONFFILES" | while read CONFFILE MD5SUMS; do
+                if [ "$2" ]; then
+		    # It's actually quite possible that the file still
+		    # "belongs" to us, and that we can avoid a costly call to
+		    # dpkg-query --search.
+                    rm_conffile logcheck-database "$CONFFILE"
+                fi
+
+                rm_old_conffile logcheck-database "$CONFFILE" $MD5SUMS
+            done
+        fi
     ;;
 
     abort-upgrade)

-- 
I did this 'cause Linux gives me a woody.  It doesn't generate revenue.
		-- Dave '-ddt->` Taylor, announcing DOOM for Linux