Improve no disk space error handling when updating plugins

[Daedalon]

I received the following uninformative error message when trying to update a plugin (roughly translated from Finnish):

Error on updating BulletProof Security. Cannot create folder. /[WPDIR]/wp-content/upgrade/bulletproof-security.tmp.

The error was caused by not having enough disk space. The plugin update should check if that's the reason for the error and then display a more informative error message.

[csixty4]

It's a great idea from a user experience standpoint, but complicated by the fact PHP's filesystem & FTP functions don't give any kind of useful error status. The filesystem code could do a set of triage checks after failures, but that would only identify reasons that *might* have prevented an upgrade from completing.

I'm working on a plugin called ​upgrade-first-aid that does those kinds of checks outside of the plugin upgrader itself. It might be a good idea to add a disk space check (​disk_free_space()) to that plugin's code.

[thomaschr]

I thought about adding a String Variable to the Filesystem Class called lasterrordetail.
With a new method getlasterrordetail() in the Filesystem Subclasses you can get a detailed errorstring for the last occured error.

This string can then be filled in the mkdir Method.

Sounds this to much like a dirty hack because I'm not using the WP Error Class?

Greetings,

Thomas

PS: You can easily recreate the "Bug" when your disk is full and you're installing a new plugin.

PPS: Checking for a full filesystem in the path is simply a matter of calling disk_free_space($path). This holds true for the direct filesystem class, the others need to be handled differently.