Add a callback to the PruneOptions struct which calculates the number of
bytes allowed to be unused after prune is done. This way, the logic is
closer to the option parsing code.
Also, add an explicit option `unlimited` for the use case when storage
does not matter but bandwidth and time do. Internally, this sets the
maximum number of unused bytes to MaxUint64.
Rework the documentation slightly so that no more "packs" are
mentioned and it talks about "files" instead.
Make it clear in the documentation that the percentage given to
`--max-unused` is relative to the whole repository size after pruning is
done. If specified, it must be below 100%, otherwise the repository
would contain 100% of unused data, which is pointless.
I had a hard time coming up with the correct formula to calculate the
maximum number of unused bytes based on the number of used bytes. For a
fraction `p` (0 ≤ p < 1), a repo with `u` bytes used, and the number of
unused bytes `x` the following holds:
x ≤ p * (u+x)
⇔ x ≤ p*u + p*x
⇔ x - p*x ≤ p*u
⇔ x * (1-p) ≤ p*u
⇔ x ≤ p/(1-p) * u
The restic security model includes full trust of the local machine, so
this should not fix any actual security problems, but it's better to be
safe than sorry.
Fixes #2192.
The file permissions included a go specific directory bit which
accidentially forced the usage of the GNU header format. This leads
to problems with 7zip on Windows or when extended attributes are
used.
The VSS support works for 32 and 64-bit windows, this includes a check that
the restic version matches the OS architecture as required by VSS. The backup
operation will fail the user has not sufficient permissions to use VSS.
Snapshotting volumes also covers mountpoints but skips UNC paths.
Cache locations were documented inconsistently in three places.
The backup docs mentioned PATH being used to find fusermount, which is
never run by restic backup. It now mentions ssh and rclone, which are
used by backends.
The notion of a "system-wide" environment variable makes no sense.
TMPDIR is now mentioned because it allows for optimization and may
have security implications.
