As mentioned in issue [#1560](https://github.com/restic/restic/pull/1560#issuecomment-364689346)
this changes the signature for `backend.Save()`. It now takes a
parameter of interface type `RewindReader`, so that the backend
implementations or our `RetryBackend` middleware can reset the reader to
the beginning and then retry an upload operation.
The `RewindReader` interface also provides a `Length()` method, which is
used in the backend to get the size of the data to be saved. This
removes several ugly hacks we had to do to pull the size back out of the
`io.Reader` passed to `Save()` before. In the `s3` and `rest` backend
this is actively used.
This is a bug fix: Before, when the worker function fn in List() of the
RetryBackend returned an error, the operation is retried with the next
file. This is not consistent with the documentation, the intention was
that when fn returns an error, this is passed on to the caller and the
List() operation is aborted. Only errors happening on the underlying
backend are retried.
The error leads to restic ignoring exclusive locks that are present in
the repo, so it may happen that a new backup is written which references
data that is going to be removed by a concurrently running `prune`
operation.
The bug was reported by a user here:
https://forum.restic.net/t/restic-backup-returns-0-exit-code-when-already-locked/484
Before, all backend implementations were required to return an error if
the file that is to be written already exists in the backend. For most
backends, that means making a request (e.g. via HTTP) and returning an
error when the file already exists.
This is not accurate, the file could have been created between the HTTP
request testing for it, and when writing starts. In addition, apart from
the `config` file in the repo, all other file names have pseudo-random
names with a very very low probability of a collision. And even if a
file name is written again, the way the restic repo is structured this
just means that the same content is placed there again. Which is not a
problem, just not very efficient.
So, this commit relaxes the requirement to return an error when the file
in the backend already exists, which allows reducing the number of API
requests and thereby the latency for remote backends.
During the development of #1524 I discovered that the Google Cloud
Storage backend did not yet use the HTTP transport, so things such as
bandwidth limiting did not work. This commit does the necessary magic to
make the GS library use our HTTP transport.
This is a follow-up on fb9729fdb9, which
runs the `ssh` in its own process group and selects that process group
as the foreground group. After the sftp connection is established,
restic switches back to the previous foreground process group.
This allows `ssh` to prompt for the password, but it won't receive
the interrupt signal (SIGINT, ^C) later on, because it is not in the
foreground process group any more, allowing a clean tear down.
We added previously a code to fix the issue of chaining
credentials, we do not need this anymore since the
upstream minio-go already has this relevant change.
Before, creating a new repo via REST would use the defaut HTTP client,
which is not a problem unless the server uses HTTPS and a TLS
certificate which isn't signed by a CA in the system's CA store. In this
case, all commands work except the 'init' command, which fails with a
message like "invalid certificate".
