From 44f7cae115e5e16d593d771bb6997dffb66f1212 Mon Sep 17 00:00:00 2001
From: Christoph Klaffl <christoph@phreaker.eu>
Date: Thu, 13 Feb 2020 01:01:09 +0100
Subject: [PATCH] implemented pre pruning script hook

---
 sanoid               | 21 +++++++++++++++++++--
 sanoid.conf          |  2 ++
 sanoid.defaults.conf |  1 +
 3 files changed, 22 insertions(+), 2 deletions(-)

diff --git a/sanoid b/sanoid
index c280d46..f9dfe33 100755
--- a/sanoid
+++ b/sanoid
@@ -316,6 +316,25 @@ sub prune_snapshots {
 					if (checklock('sanoid_pruning')) {
 						writelock('sanoid_pruning');
 						foreach my $snap( @prunesnaps ){
+							my $dataset = (split '@', $snap)[0];
+							my $snapname = (split '@', $snap)[1];
+
+							if (! $args{'readonly'} && $config{$dataset}{'pre_pruning_script'}) {
+								$ENV{'SANOID_TARGET'} = $dataset;
+								$ENV{'SANOID_SNAPNAME'} = $snapname;
+								if ($args{'verbose'}) { print "executing pre_pruning_script '".$config{$dataset}{'pre_pruning_script'}."' on dataset '$dataset'\n"; }
+								my $ret = runscript('pre_pruning_script', $dataset);
+
+								delete $ENV{'SANOID_TARGET'};
+								delete $ENV{'SANOID_SNAPNAME'};
+
+								if ($ret != 0) {
+									# warning was already thrown by runscript function
+									# skip pruning if pre snapshot script returns non zero exit code
+									next;
+								}
+							}
+
 							if ($args{'verbose'}) { print "INFO: pruning $snap ... \n"; }
 							if (!$args{'force-prune'} && iszfsbusy($path)) {
 								if ($args{'verbose'}) { print "INFO: deferring pruning of $snap - $path is currently in zfs send or receive.\n"; }
@@ -323,8 +342,6 @@ sub prune_snapshots {
 								if (! $args{'readonly'}) {
 									if (system($zfs, "destroy", $snap) == 0) {
 										$pruned{$snap} = 1;
-										my $dataset = (split '@', $snap)[0];
-										my $snapname = (split '@', $snap)[1];
 										if ($config{$dataset}{'pruning_script'}) {
 											$ENV{'SANOID_TARGET'} = $dataset;
 											$ENV{'SANOID_SNAPNAME'} = $snapname;
diff --git a/sanoid.conf b/sanoid.conf
index 6bd5c62..6d982bc 100644
--- a/sanoid.conf
+++ b/sanoid.conf
@@ -97,6 +97,8 @@
 	pre_snapshot_script = /path/to/script.sh
 	### run script after snapshot
 	post_snapshot_script = /path/to/script.sh
+	### run script before pruning snapshot
+	pre_pruning_script = /path/to/script.sh
 	### run script after pruning snapshot
 	pruning_script = /path/to/script.sh
 	### don't take an inconsistent snapshot (skip if pre script fails)
diff --git a/sanoid.defaults.conf b/sanoid.defaults.conf
index a9ca382..d65601c 100644
--- a/sanoid.defaults.conf
+++ b/sanoid.defaults.conf
@@ -21,6 +21,7 @@ skip_children =
 
 pre_snapshot_script =
 post_snapshot_script =
+pre_pruning_script =
 pruning_script =
 script_timeout = 5
 no_inconsistent_snapshot =