From a17131aaf1458daf178dee7f745be2877016d1b9 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Peter=20Valdemar=20M=C3=B8rch?= <peter@morch.com>
Date: Thu, 27 Feb 2025 19:57:43 +0100
Subject: [PATCH] Fix BTRFS_SEND_C_CLONE

It now aligns with https://github.com/torvalds/linux/blob/dd83757f6e686a2188997cb58b5975f744bb7786/fs/btrfs/send.c#L5394

This maybe fixes #22.

Without this, I got this error:

Traceback (most recent call last):
  File "/home/peter/work/btrfs-snapshots-diff/./btrfs-snapshots-diff.py", line 653, in <module>
    main()
  File "/home/peter/work/btrfs-snapshots-diff/./btrfs-snapshots-diff.py", line 620, in main
    commands, paths = stream.decode(bogus=args.bogus)
                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/peter/work/btrfs-snapshots-diff/./btrfs-snapshots-diff.py", line 325, in decode
    offset2, path = self._tlv_get_string('BTRFS_SEND_A_PATH', offset)
                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/peter/work/btrfs-snapshots-diff/./btrfs-snapshots-diff.py", line 105, in _tlv_get_string
    raise ValueError(f'Unexpected attribute {self.send_attrs[attr]}')
ValueError: Unexpected attribute BTRFS_SEND_A_FILE_OFFSET

And according to btrfs/send.c BTRFS_SEND_A_PATH not supposed to be sent as the first
element of a BTRFS_SEND_C_CLONE, but BTRFS_SEND_A_FILE_OFFSET is.

The patch to create-example.sh causes the test to fail, but I cannot
fix them because of #23.
---
 btrfs-snapshots-diff.py | 16 +++++++++-------
 create-example.sh       |  2 ++
 2 files changed, 11 insertions(+), 7 deletions(-)

diff --git a/btrfs-snapshots-diff.py b/btrfs-snapshots-diff.py
index 8cd1ce4..8ffdd29 100755
--- a/btrfs-snapshots-diff.py
+++ b/btrfs-snapshots-diff.py
@@ -322,22 +322,24 @@ def decode(self, bogus=True):
                 )
 
             elif command == 'BTRFS_SEND_C_CLONE':
-                offset2, path = self._tlv_get_string('BTRFS_SEND_A_PATH', offset)
                 offset2, file_offset = self._tlv_get_u64(
-                    'BTRFS_SEND_A_FILE_OFFSET', offset2
+                    'BTRFS_SEND_A_FILE_OFFSET', offset
                 )
                 offset2, clone_len = self._tlv_get_u64(
                     'BTRFS_SEND_A_CLONE_LEN', offset2
                 )
+                offset2, path = self._tlv_get_string(
+                    'BTRFS_SEND_A_PATH', offset2
+                )
                 offset2, clone_uuid = self._tlv_get_uuid(
                     'BTRFS_SEND_A_CLONE_UUID', offset2
                 )
-                offset2, clone_transid = self._tlv_get_u64(
-                    'BTRFS_SEND_A_CLONE_TRANSID', offset2
+                offset2, clone_ctransid = self._tlv_get_u64(
+                    'BTRFS_SEND_A_CLONE_CTRANSID', offset2
                 )
                 offset2, clone_path = self._tlv_get_string(
-                    'BTRFS_SEND_A_CLONE_PATH', offset
-                )  # BTRFS_SEND_A_CLONE8PATH
+                    'BTRFS_SEND_A_CLONE_PATH', offset2
+                )
                 offset2, clone_offset = self._tlv_get_u64(
                     'BTRFS_SEND_A_CLONE_OFFSET', offset2
                 )
@@ -349,7 +351,7 @@ def decode(self, bogus=True):
                         'file_offset': file_offset,
                         'clone_len': clone_len,
                         'clone_uuid': clone_uuid,
-                        'clone_transid': clone_transid,
+                        'clone_transid': clone_ctransid,
                         'clone_path': clone_path,
                         'clone_offset': clone_offset,
                     }
diff --git a/create-example.sh b/create-example.sh
index 8b6d03f..f50274a 100755
--- a/create-example.sh
+++ b/create-example.sh
@@ -32,6 +32,8 @@ mkfifo fifo
 ln file hardlink
 ln -s file symlink
 echo 'Hello Btrfs' > 'xxx;yyy;zzz'
+dd if=/dev/zero of=source bs=1024 count=1024 > /dev/null 2>&1
+cp --reflink=always source bbbb
 mv file file2
 cd ..