From f8d0b27dcb64f0e6f03d1c3cf2cb85277a017a98 Mon Sep 17 00:00:00 2001
From: Mark Wooding <mdw@distorted.org.uk>
Date: Fri, 14 Dec 2012 23:07:33 +0000
Subject: [PATCH] rsync-backup.8, rsync-backup.in: Allow per-backup retention
 policy.

Now stuff like the media library doesn't keep old mistakes and changed
files forever, but we can still keep lots of history for most of the
filesystems.
---
 rsync-backup.8  | 29 ++++++++++++++++++++++++++++-
 rsync-backup.in | 18 ++++++++++++++++--
 2 files changed, 44 insertions(+), 3 deletions(-)

diff --git a/rsync-backup.8 b/rsync-backup.8
index 20682ea..4ba5952 100644
--- a/rsync-backup.8
+++ b/rsync-backup.8
@@ -156,7 +156,10 @@ will avoid inefficient and pointless messing about
 in this case.
 This command clears the
 .B like
-list.
+list, and resets the retention policy to its default (i.e., the to
+policy defined prior to the first
+.B host
+command).
 .TP
 .BI "like " "host\fR ..."
 Declare that subsequent filesystems are `similar' to like-named
@@ -197,6 +200,30 @@ or
 Expiry considers each existing dump against the policy lines in order:
 the last applicable line determines the dump's fate \(en so you should
 probably write the lines in decreasing order of duration.
+.PP
+Groups of
+.B retain
+commands between
+.B host
+and/or
+.B backup
+commands collectively define a retention policy.  Once a policy is
+defined, subsequent
+.B backup
+operations use the policy.  The first
+.B retain
+command after a
+.B host
+or
+.B backup
+command clears the policy and starts defining a new one.  The policy
+defined before the first
+.B host
+is the
+.I default
+policy: at the start of each
+.B host
+stanza, the policy is reset to the default.
 .TP
 .BI "retry " count
 The
diff --git a/rsync-backup.in b/rsync-backup.in
index 292c6eb..7519b12 100644
--- a/rsync-backup.in
+++ b/rsync-backup.in
@@ -130,7 +130,7 @@ hostrun () {
 
 _hostrun () {
   h=$1 cmd=$2
-  ## Like hostrun, but without the complicated logging, but targetted at a
+  ## Like hostrun, but without the complicated logging, and targetted at a
   ## specific host.
 
   if localp $h; then sh -c "$cmd"
@@ -667,10 +667,14 @@ do_backup () {
   $verbose "	commit"
 
   ## Expire old backups.
+  case "${expire_policy+t},${default_policy+t}" in
+    ,t) expire_policy=$default_policy ;;
+  esac
   case "${expire_policy+t},$dryrun" in
     t,nil) run "expiry for $host:$fs" expire_backups ;;
     t,t) expire_backups ;;
   esac
+  clear_policy=t
 
   ## Report success.
   case $dryrun in
@@ -776,13 +780,23 @@ backup () {
 ###--------------------------------------------------------------------------
 ### Configuration functions.
 
-host () { host=$1; like=; $verbose "host $host"; }
+host () {
+  host=$1
+  like=
+  case "${expire_policy+t},${default_policy+t}" in
+    t,) default_policy=$expire_policy ;;
+  esac
+  unset expire_policy
+  $verbose "host $host"
+}
+
 snaptype () { snap=$1; shift; snapargs="$*"; retry=0; }
 rsyncargs () { rsyncargs="$*"; }
 like () { like="$*"; }
 retry () { retry="$*"; }
 
 retain () {
+  case $clear_policy in t) unset expire_policy; clear_policy=nil ;; esac
   expire_policy="${expire_policy+$expire_policy
 }$*"
 }
-- 
2.11.0