Use part files for web UI upload

[PVince81]

Steps to reproduce

1. Prepare a bag full with luck
2. Enable encryption
3. Setup the sync client
4. Upload a lot of small files with the Web UI
5. While the Web UI is still uploading, the sync client will at some point start downloading

Expected result

No encryption error in log

Actual result

If you're (un-)luck, it might happen that the sync client sees a file while it is still being uploaded/encrypted, which results in the following:

{"reqId":"f88e81b5c643f29cba06d504d97b69b1","remoteAddr":"192.168.1.2","app":"remote","message":"Encryption key not found for \"\/root\/files\/sub10\/zegar.gif\" during attempted read via stream","level":4,"time":"2014-11-28T08:57:35+00:00"}

One solution for this would be to make files that are uploaded through the Web UI also become a part file at first, until all file operations, proxies, etc are finished (for encryption). Then at the end, rename the file to the final file.

Versions

OC 8 git master, possibly happening in any version

In general I think we should start using part files for everything related to upload.

@schiesbn @DeepDiver1975 @icewind1991

[PVince81]

I forgot to mention that the sync client will show an error when downloading that incomplete file. The next sync run will redownload it and all is fine in the end.

[DeepDiver1975]

In general I think we should start using part files for everything related to upload.

as soon as we migrate over to webdav in the browser this will be solved

[PVince81]

Closing as duplicate then: #12353