This PR adds a dynamic property so a backend can signal if it supports streaming, based on the settings.
This is currently used for the File backend, so that toggling `--use-move-for-put` will disable streaming on the backend instead of relying on the `--disable-streaming-transfers` flag.
This PR moves the check from the FTP backend into shared code, so all backends will now check for read/write permissions when using the "Test" button.
For situations where write permissions are not required (like restore or verify) there is a flag on the v2 API that indicates if the connection was established, so the UI can show a message suggesting that it is possible to proceed, if the current UI operation does not require write permissions.
This fixes#2473
Some providers, B2, Idrivee2, JottaCloud and S3 (AWS version) needs a checksum for the content.
To calculate this content the libraries will calculate the hash by reading the stream. But since the stream can be throttled, the hash calculation is throttled.
In some cases the contents are buffered, so the transfer is done at full speed, but the hashing at throttled speed. The average speed is the same, but network traffic is bursty, which it should not be with a throttle.
Also added option to disable signing with AWS Sigv4 as that interferes with the throttled stream. It is not currently possible to pass the sha-256 hash to the Sigv4 code, so it will always read the entire (potentially throttled) stream before sending the contents, causing unwanted delays. Use the new option `--s3-disable-payload-signing` to disable v4 signing.
This PR is the final change, where all backends are now purely implemented with async interfaces.
The code changes here replace the LIST call with an async version. This affect all backends (and then some) but the changes are mostly mechanical rewrites of the code.
In many places, the backeds were already prepared for async output, in other some glue was needed.
To reduce the scope of this change, some backends simply report a synchronous result as an async list.
Kenneth Skovhede