[Owncloud] kill "file" command

[Frank Karlitschek]

Hi everyone,

a question about mime type detection. 

Currently we try to detect the mimetype of every file in ownCloud. This is done on local files and also remote files. 
We first check our own mimetype list in ownCloud, than call the php mime_content_type call and if this also fails than a system "file" command is executed. The results are then stored in the filesystem cache and refreshed regularly.

The problem with the second two options is that it requires file access which is slow for encrypted files and external filesystems. For example we have to download the complete dropbox, google drive, .. where no streaming is supported, to detect the mimetypes. This is super slow of course and a nightmare. 

The question now is if we really need the exact mime type of every file? I think we could improve the performance significantly if we kill the second two detection options and only rely on our own mime type list. 


As far as I know we use the mime-types for the searchByMime call to get all files with a specific mime-type. But we only need this for well known file types like jpeg, mp3 and odt anyways. Searches for more esoteric file types are not needed and if yes then we can just add them to our list.

We also send the mime type to the browser during download. But I don't think it is a problem if we send an unknown mimetype for unknown filetypes. Apache does the same by default too.

We also use the mime types to show the correct file icons and preview in the web-interface. But we have a limited number of icons anyways so it should be ok if we just make sure that we have all this filetypes in our list.


So in my opinion we could get a very nice big speedup if we stop reading files for mime type detection. Especially external storage should be fast and usable with this change.

Do I miss something or can we do it like that?


Frank