From 5df241d700083a33999f7af8759a8b5ad2750268 Mon Sep 17 00:00:00 2001
From: Stefan Schantl <stefan.schantl@ipfire.org>
Date: Sun, 5 May 2024 16:56:47 +0200
Subject: [PATCH] filesystem-functions.pl: Add functions to get
 snapshots/subvolumes

The btrfs_get_snapshots() and btrfs_get_subvolumes() functions are
designed to be used to get the desired details.

Signed-off-by: Stefan Schantl <stefan.schantl@ipfire.org>
---
 config/cfgroot/filesystem-functions.pl | 90 ++++++++++++++++++++++++++
 1 file changed, 90 insertions(+)

diff --git a/config/cfgroot/filesystem-functions.pl b/config/cfgroot/filesystem-functions.pl
index d48cbe1f6..6b041bc17 100644
--- a/config/cfgroot/filesystem-functions.pl
+++ b/config/cfgroot/filesystem-functions.pl
@@ -614,4 +614,94 @@ sub btrfs_subvolume_snapshot ($$$) {
 	return;
 }
 
+#
+## Easy to use function to get all created snapshots of a given volume.
+##
+## It uses the filter_subvolume_list function to only provide snapshots and
+## returns the data in the same way as recieved.
+#
+sub btrfs_get_snapshots ($) {
+	my ($volume) = @_;
+
+	my %snapshots = &_filter_subvolume_list (
+		"volume" => $volume,
+		"type" => "snapshots"
+	);
+
+	return %snapshots;
+}
+
+#
+## Easy to use function to get the subvolumes of a given BTRFS volume.
+##
+## It also uses the filter_subvolume_list function only provide subvolumes
+## returns the data in the same way as recieved.
+#
+sub btrfs_get_subvolumes ($) {
+	my ($volume) = @_;
+
+	my %subvolumes = &_filter_subvolume_list (
+		"volume" => $volume,
+		"type" => "subvolumes"
+	);
+
+	return %subvolumes;
+}
+
+#
+## Private function to filter the output of btrfs_subvolume_list command.
+##
+## It can be used to return subvolumes or snapshots and will return them
+## as a hash with the format "ID" => "path".
+##
+## Example: "256" => "@root" (in case subvolumes should be dispalyed.
+##          "xxx" => "<name>" (in case snapshots are requested and at least one exist)
+#
+sub _filter_subvolume_list (%) {
+	my (%options) = @_;
+
+	# Hash to translate filter type into level number.
+	my %level = (
+		"subvolumes" => "5",
+		"snapshots" => "257"
+	);
+
+	# Assign options values.
+	my $volume = $options{"volume"} if ($options{"volume"});
+	my $type = $options{"type"} if ($options{"type"});
+	my $filter_level = $level{$type} if ($type);
+	
+	# Hash to store the filtered subvolumes.
+	my %subvolumes;
+
+	# Call btrfs_subvolume_list function to get a list of all known subvolumes and snapshots.
+	my @output = &btrfs_subvolume_list($volume);
+
+	# Loop through the output array of the btrfs subvolumes list command.
+	foreach my $line (@output) {
+		# Parse the line and assign humand readable values.
+		$line =~ /ID (.*) gen (.*) top level (.*) path (.*)/ || next;
+		my ($id, $gen, $level, $path) = ($1, $2, $3, $4);
+
+		# Skip current line if only a certain type is requested.
+		next if (($type) && ($level ne $filter_level));
+
+		# Check if snapshots are requested.
+		if ($type eq "snapshots") {
+			# Split the returned path into pieces to only return the
+			# name of the snapshot without subvolume details.
+			my ($subvol, $name) = split("/", $path);
+
+			# Assign the snapshot name as path.
+			$path = $name;
+		}
+
+		# Assign the current element to the hash of subvolumes.
+		$subvolumes{$id} = $path;
+	}
+
+	# Return a hash reference.
+	return %subvolumes;
+}
+
 1;
-- 
2.39.5