Regroup marshling/unmarshaling and lint

[puellanivis]

This covers a few different things that were somewhat unrelated to starting to use filexfer but will make that transfer easier.

• Collects and isolates marshal/unmarshal code into packets.go
• Removing clamp and min functions that both did the same thing, and didn’t really contribute to more understandable code.
• Fix corner cases in os.ModeType → uint32 where we treat the various types as bitfields that can be OR’ed together rather than mutually exclusive values.
• a small bit of linting on request-server.go
• fileInfo can use the values in the wrapped FileStat, which we also don’t need to treat as an any.
• bring over the ls_formatting from PR-432, as this is an improvement beyond just bringing in filexfer as it extracts more UID/GID values for the various GOOS, supports setting UID/GID values from a FileStat, and also converts UIDs/GIDs to usernames and groupnames when possible. (Do we really want to use system-wide username/groupnames? Might be good to provide an ability to override this? Since request-server might be operating entirely disjoint from the underlying OS.)
• removed a few cgo build conditions that were not actually necessary
• verified that the code compiles for all GOOS supported in go1.16 (not verified that it works, just that it compiles)

[puellanivis]

I should run a regression test on this with FileZilla… since I’m touching the longname field…

[drakkan]

Hi,

I just tested with FileZilla and it seems ok. SFTPGo test cases also passed.

I'm not sure about UIDs/GIDs to usernames and groupnames conversion, however we may allow you to override the conversion in the future if needed. Thanks!

[drakkan]

The directory listing is now something like this

sftp> ls -la
drwxr-xr-x    1 0        0               0 Aug 16 07:19 .
drwxr-xr-x    1 0        0               0 Aug 16 07:19 local
-rw-r--r--    1 nicola   nicola       4034 Aug 16 07:19 file.txt
drwxr-xr-x    1 0        0               0 Aug 16 07:19 vdir1
drwxr-xr-x    1 0        0               0 Aug 16 07:19 vdir2
drwxr-xr-x    1 0        0               0 Aug 16 07:19 vdir3

., local, vdir1, vdir2, vdir3 are virtual directory and so UIDs/GIDs are not converted. The same happen for cloud storage based accounts. For non local files/dirs the type assertion fails and so no conversion happen. I think this is ok for now. Maybe if future we could allow to disable this conversion (it could slow down directory listing if we have a lot of entries) using a setting or provide an optional interface

[puellanivis]

Yeah, I was thinking of abstracting it away to an optional interface as well. It shouldn’t be too hard. 🤔

[puellanivis]

I’ve spun off the username and groupname lookup into an extension type on FileLister, default behavior for RequestServer should end up as “do not convert UID/GID from numbers”, and default unoverridable behavior for Server is to use os/user for username and groupname lookup.

[drakkan]

it looks good for me, thanks