As of btrfs-progs-v4.12, the "btrfs subvolume show" command does not
print the full (absolute, resolved) path anymore [1]. Instead, it prints
the relative path to btrfs root (or "/" if it is the root).
The impact for btrbk is that we cannot fill our realpath_cache in
btrfs_subvolume_show() anymore. This is not fatal, but has the
following consequences:
- The "check for duplicate snapshot locations" may now miss
subvolumes specified by symlinks.
- If multiple "volume" sections point to the same subvolume (e.g. if
specified using symlinks) an additional "btrfs subvolume list" is
called. Note that the subvolume will still be recognized as
identical, and the btr_tree will not be rebuilt.
[1] btrfs-progs commit: b7df24aa5cddc4802b9938f56372b73869775cd9
This gets important when using an old backup disk as source.
In terms of btrfs send/receive, all subvolumes matching "uuid /
received_uuid" are valid backups.
Merged (amend) from pull request: #116
Verified by Axel Burri <axel@tty0.ch>
We set "--no-random-seed-file" because one of the btrbk
design principles is to not create any files unasked. Enabling
"--no-random-seed-file" creates ~/.gnupg/random_seed, and as
such depends on $HOME to be set correctly (think on running in
cron). From gpg2(1) man page:
--no-random-seed-file GnuPG uses a file to store its
internal random pool over invocations This makes random
generation faster; however sometimes write operations are not
desired. This option can be used to achieve that with the cost
of slower random generation.
We use "dd" instead of shell redirections, as it is common to have
special filesystems (like NFS, SMB, FUSE) mounted on the raw target
path. By using "dd" we make sure to write in reasonably large blocks
(default=128K), which is not always the case when using redirections
(e.g. "gpg > outfile" writes in 8K blocks).
Another approach would be to always pipe through "cat", which uses
st_blksize from fstat(2) (with a minimum of 128K) to determine the
block size.
bugfix for: 796b6bd9bf
Replace realpath with readlink in allowed commands. Commit 796b6bd substituted readlink for realpath in file "btrbk"; this commit propagates the change to ssh_filter_btrbk.sh.
Add configuration option transaction_syslog, which can be set to a short
name of a syslog facility, like user or local5. Most of the ones besides
localX do not really make sense, but whatever, let the user decide.
The only logging that is relevant for logging to syslog is the logging
generated inside sub action, so it's easy to hijack all messages in
there and also send them to syslog if needed.
All output is done via print_formatted, which expects a file handle.
So, abuse a file handle to a string to be able to change as less code as
needed for this feature.
Since syslog already adds the timestamps for us, I added a syslog
formatting pattern, which is very similar to tlog, omitting the
timestap.
Axel Burri