From f5ac493bbdf269f51ac861e1503c3834dea79b9d Mon Sep 17 00:00:00 2001
From: thiswillbeyourgithub
 <26625900+thiswillbeyourgithub@users.noreply.github.com>
Date: Tue, 16 Sep 2025 14:52:52 +0200
Subject: [PATCH 1/2] feat: crash if template can't be found

Signed-off-by: thiswillbeyourgithub <26625900+thiswillbeyourgithub@users.noreply.github.com>
---
 sanoid | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/sanoid b/sanoid
index 8e0d186..1e32ecd 100755
--- a/sanoid
+++ b/sanoid
@@ -1020,6 +1020,12 @@ sub init {
 				$rawtemplate =~ s/\s+$//g;
 
 				my $template = 'template_'.$rawtemplate;
+
+                # Check if template exists
+                if (!exists $ini{$template}) {
+                    die "FATAL ERROR: Template '$rawtemplate' referenced in section [$section] does not exist in $conf_file.\n";
+                }
+
 				foreach my $key (keys %{$ini{$template}}) {
 					if ($key =~ /template|recursive/) {
 						warn "ignored key '$key' from '$rawtemplate' template.\n";

From 88a09b141ee8f60758d4f4f94d268dae9cbcb4d4 Mon Sep 17 00:00:00 2001
From: thiswillbeyourgithub
 <26625900+thiswillbeyourgithub@users.noreply.github.com>
Date: Tue, 16 Sep 2025 15:00:44 +0200
Subject: [PATCH 2/2] feat: crash if found unused templates

Signed-off-by: thiswillbeyourgithub <26625900+thiswillbeyourgithub@users.noreply.github.com>
---
 sanoid | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/sanoid b/sanoid
index 1e32ecd..d119574 100755
--- a/sanoid
+++ b/sanoid
@@ -1145,6 +1145,35 @@ sub init {
 		}
 	}
 
+    # Check for unused templates
+    my %defined_templates;
+    my %used_templates;
+
+    # Collect all defined templates
+    foreach my $section (keys %ini) {
+        if ($section =~ /^template_(.+)$/) {
+            $defined_templates{$1} = 1;
+        }
+    }
+
+    # Collect all used templates
+    foreach my $section (keys %ini) {
+        if ($section !~ /^template_/ && defined $ini{$section}{'use_template'}) {
+            my @templates = split (' *, *', $ini{$section}{'use_template'});
+            foreach my $rawtemplate (@templates) {
+                $rawtemplate =~ s/\s+$//g; # strip trailing whitespace
+                $used_templates{$rawtemplate} = 1;
+            }
+        }
+    }
+
+    # Check for unused templates (excluding template_default)
+    foreach my $template (keys %defined_templates) {
+        if ($template ne 'default' && !exists $used_templates{$template}) {
+            die "FATAL ERROR: Template '$template' is defined but never used in $conf_file.\n";
+        }
+    }
+
 	return %config;
 } # end sub init