[RFC PATCH v3 3/9] common/encrypt: add btrfs to get_ciphertext_filename

[Sweet Tea Dorminy <sweettea-kernel@dorminy.me>]

Add the relevant call to get an encrypted filename from btrfs.

Signed-off-by: Sweet Tea Dorminy <sweettea-kernel@dorminy.me>
---
 common/encrypt | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/common/encrypt b/common/encrypt
index fc1c8cc7..2c1925da 100644
--- a/common/encrypt
+++ b/common/encrypt
@@ -618,6 +618,19 @@ _get_ciphertext_filename()
 	local dir_inode=$3
 
 	case $FSTYP in
+	btrfs)
+		# Extract the filename from the inode_ref object, similar to:
+		# item 24 key (259 INODE_REF 257) itemoff 14826 itemsize 26
+		# 	index 3 namelen 16 name: J\xf7\x15tD\x8eL\xae/\x98\x9f\x09\xc1\xb6\x09>
+		#
+		$BTRFS_UTIL_PROG inspect-internal dump-tree $device | \
+			grep -A 1 "key ($inode INODE_REF " | tail -n 1 | \
+			perl -ne '
+				s/.*?name: //;
+				chomp;
+				s/\\x([[:xdigit:]]{2})/chr hex $1/eg;
+				print;'
+		;;
 	ext4)
 		# Extract the filename from the debugfs output line like:
 		#
@@ -715,6 +728,9 @@ _require_get_ciphertext_filename_support()
 			_notrun "dump.f2fs (f2fs-tools) is too old; doesn't support showing unambiguous on-disk filenames"
 		fi
 		;;
+	btrfs)
+		_require_command "$BTRFS_UTIL_PROG" btrfs
+		;;
 	*)
 		_notrun "_get_ciphertext_filename() isn't implemented on $FSTYP"
 		;;
-- 
2.41.0