Added support to enable object lock on bucket creation in posix and azure
backends.
Implemented the logic to add object legal hold and retention on object creation
in azure and posix backends.
Added the functionality for HeadObject to return object lock related headers.
Added integration tests for these features.
When fileystem quota exceeded, the gateway will now return the
error:
S3 error: 403 (QuotaExceeded):
Your request was denied due to quota exceeded.
This will help clients to better detect upload errors due to
quota exceeded.
Fixes#483
Since objects with trailing "/" are mapped to directories in the
posix filesystem, they must not contain data since there is no
place to store that data.
This checks both PutObject and CreateMultipartUpload for invalid
directory object types containing data.
