Optional interfaces are becoming more important in rclone,
--track-renames and --backup-dir both rely on them.
Up to this point rclone has used interface upgrades to define optional
behaviour on Fs objects. However when one Fs object wraps another it
is very difficult for this scheme to work accurately. rclone has
relied on specific error messages being returned when the interface
isn't supported - this is unsatisfactory because it means you have to
call the interface to see whether it is supported.
This change enables accurate detection of optional interfaces by use
of a Features struct as returned by an obligatory Fs.Features()
method. The Features struct contains flags and function pointers
which can be tested against nil to see whether they can be used.
As a result crypt and hubic can accurately reflect the capabilities of
the underlying Fs they are wrapping.
These are set in the form RCLONE_CONFIG_remote_option where remote is
the uppercased remote name and option is the uppercased config file
option name. Note that RCLONE_CONFIG_remote_TYPE must be set if
defining a new remote.
Fixes#616
If remote:path points to a file make NewFs return a sentinel error
fs.ErrorIsFile and an Fs which points to the parent.
Use this to remove the LimitedFs and just add this file to the
--files-from list.
This means that server side operations can be used also.
Fixes#518Fixes#545
Gives more accurate error propagation, control of depth of recursion
and short circuit recursion where possible.
Most of the the heavy lifting is done in the "fs" package, making file
system implementations a bit simpler.
This commit contains some code originally by Klaus Post.
Fixes#316
Chunks aren't buffered in memory, so chose 128M as the default size as
producing the maximum throughput. This takes the throughput from 78
kBytes/s to 4MBytes/s a 50x improvement!
This means that dropbox no longer stores MD5SUMs and modified times.
Fixup the tests so that blank MD5SUMs are ignored, and that if
Precision is set to a fs.ModTimeNotSupported, ModTimes can be ignored too.
This opens the door for other FSs which don't support metadata easily.
...unless had some errors or stats interval requested.
Add fs.ErrorLog to differentiate between Logs which should be
suppressed and errors which shouldn't.
