rclone returns a "not found" error if an internal error occurs while
listing a folder. Ignoring this error lets restic erroneously think that
there are no files, which can cause `prune` to wipe the whole
repository.
This removes code that is only used within a backend implementation from
the backend package. The latter now only contains code that also has
external users.
Allow setting custom arguments for the `sftp` backend, by using the
`sftp.args` option. This is similar to the approach already implemented
in the `rclone` backend, to support new arguments without requiring
future code changes for each different SSH argument.
Closes #4241
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.
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.
Conceptually the backend configuration should be validated when creating
or opening the backend, but not when filling in information from
environment variables into the configuration.
This unified construction removes most backend-specific code from
global.go. The backend registry will also enable integration tests to
use custom backends if necessary.
In order to change the backend initialization in `global.go` to be able
to generically call cfg.ApplyEnvironment() for supported backends, the
`interface{}` returned by `ParseConfig` must contain a pointer to the
configuration.
An alternative would be to use reflection to convert the type from
`interface{}(Config)` to `interface{}(*Config)` (from value to pointer
type). However, this would just complicate the type mess further.
