For `restic backup`, support new flags
`--changed-files-from-verbatim` and `--changed-files-from-raw` to
read the files/dirs that actually have changed from a file (or
multiple files). Directories that don't (directly or indirectly)
contain any changed files/dirs will reuse the corresponding subtree
of the parent snapshot.
This option is useful for higher-level backup tools which use
restic as a backend but have their own mechanism of figuring out
which files have changed (e.g., using zfs or btrfs diff tools).
We require to explicitly pass `--parent` as a protection mechanism
in order to make sure the higher-level backup tool and restic agree
on the parent snapshot. Though the caller can circumvent this
protection mechanism by passing `--parent latest`.
Caveat: since device IDs are unstable (across reboots or across
different zfs/btrfs snapshots of the same subvolume), the parent
snapshot and current snapshot might have mismatching device IDs.
In this case, the feature will still reuse subtrees of the parent
snapshot (under the conditions mentioned above), so we end up with
a snapshot that contains subtrees with different `device_id`
values, even if there was only a single mountpoint in play.
For now, we could simply document this caveat and discourage users
who rely on correct restoration of hardlinks from using this
feature. When https://github.com/restic/restic/issues/3041 is
properly fixed in the future, then this caveat probably goes away,
too.
The idea for this feature emerged here:
https://github.com/restic/restic/issues/1502#issuecomment-1721956623
The old version was taken from an MPL-licensed library. This is a
cleanroom implementation. The code is shorter and it's now explicit that
only Linux ACLs are supported.
The test uses `WithTimeout` to create a context that cancels the List
operation after a given delay. Several backends internally use a derived
child context created using WithCancel.
The cancellation of a context first closes the done channel of the
context (here: the `WithTimeout` context) and _afterwards_ propagates
the cancellation to child contexts (here: the `WithCancel` context).
Therefor if the List implementation uses a child context, then it may
take a moment until that context is also cancelled. Thus give the
context cancellation a moment to propagate.
A stale lock may be refreshed if it continues to exist until after a
replacement lock has been created. This ensures that a repository was
not unlocked in the meantime.
When transferring a repository from S3 to, for example, a local disk
then all empty folders will be missing.
When saving files, the missing intermediate folders are created
automatically. Therefore, missing directories can be ignored by the
`List()` operation.
Linux allows the use of non-`user.` extended attributes on symlinks. One
of the main users of this functionality is SELinux's `security.selinux`
xattr for storing a path's label. By storing symlink xattrs, restic is
now suitable for backing up the root filesystem on Linux distributions
that use SELinux.
This commit adds support for symlink xattrs when backing up data,
restoring data, and mounting snapshots via a fuse mount. All calls to
the xattr library have been updated to the use `L` variants of the
various functions, which always operate on the path given, without
following symlinks.
Fixes: #4375
Signed-off-by: Andrew Gunnerson <accounts+github@chiller3.com>
