During some other work I discovered these tests weren't great, so I've
rewritten them to be a little better. The real changes here are:
- Don't play games with not starting the folder and such, and don't
construct a fake folder instance -- just use the one the model has. The
folder starts and scans but the folder contents are empty at this point
so that's fine.
- Use a fakefs instead of a temp dir.
- To support the above, implement a fakefs option `?content=true` to
make the fakefs actually retain written content. Use sparingly,
obviously, but it means the fakefs can usually be used instead of an
on disk real directory.
This adds a folder option "CopyOwnershipFromParent" which, when set,
makes Syncthing attempt to retain the owner/group information when
syncing files. Specifically, at the finisher stage we look at the parent
dir to get owner/group and then attempt a Lchown call on the temp file.
For this to succeed Syncthing must be running with the appropriate
permissions. On Linux this is CAP_FOWNER, which can be granted by the
service manager on startup or set on the binary in the filesystem. Other
operating systems do other things, but often it's not required to run as
full "root". On Windows this patch does nothing - ownership works
differently there and is generally less of a deal, as permissions are
inherited as ACLs anyway.
There are unit tests on the Lchown functionality, which requires the
above permissions to run. There is also a unit test on the folder which
uses the fake filesystem and hence does not need special permissions.
* lib/fs: Add fakefs
This adds a new fake filesystem type. It's described rather extensively
in fakefs.go, but the main point is that it's for testing: when you want
to spin up a Syncthing and have a terabyte or two of random files that
can be synced somewhere, or an inifitely large filesystem to sync files
into.
It has pseudorandom properties such that data read from one fakefs can
be written into another fakefs and read back and it will look
consistent, without any of the data actually being stored.
To use:
<folder id="default" path="whatever" ...>
<filesystemType>fake</filesystemType>
This will create an empty fake filesystem. You can also specify that it
should be prefilled with files:
<folder id="default" path="whatever?size=2000000" ...>
<filesystemType>fake</filesystemType>
This will create a filesystem filled with 2TB of random data that can be
scanned and synced. There are more options, see fakefs.go.
Prefilled data is based on a deterministic seed, so you can index the
data and restart Syncthing and the index is still correct for all the
stored data.
