File permissions if only FTP access

We run OJS with a webhosting provider, therefore we have only access to the server with FTP. We cannot find out the name of the user who runs the PHP scripts and we cannot chown the files to him. (But we do have the files directory above the web directory.) Updating to or installing OJS 3 did not work (as discussed here), possibly because of the wrong file permissions. PHP is set to Fast-CGI. Before we try to install OJS3 again, I want to know:

Is it true that if I set permissions of, the files dir, ./cache/, ./public/, /plugins/ and of /locale/ to 777 and the problem persists, then I know that lack of permissions is not the cause of the problem?

I have read this and this FAQ on this. asmecher wrote in the former: “Note that 777 permissions can be useful for debugging, but they are never safe to use.”

Hi @Aragon,

There are other things that could be at play – e.g. if your server uses SELinux extensions, which introduce permissions beyond the normal user/numeric codes.

It’s going to be very difficult to figure out what to use experimentally and land on a configuration that you’re confident is both functional and safe; it really should be possible to inquire about the server’s setup and set your permissions accordingly.

Alec Smecher
Public Knowledge Project Team