[Dev-luatex] file permissions

Hans Hagen pragma at wxs.nl
Sun Feb 6 23:33:37 CET 2011


On 6-2-2011 3:56, Reinhard Kotucha wrote:

> $ whoami
> reinhard
> $ ls -l /etc/passwd
> -rw-r--r-- 1 root root 2269 Dec 19 14:57 /etc/passwd
>
> Your test suggests that the file is writable, but this is only true
> for root, not for the user who is running the script.  You actually
> have to determine whether you are the owner of the file, or, if the
> file is group writable, whether you are member of this group, or
> whether the file is writable by everybody.

Isn't it a bug in the lfs library then? When is the point in returning 
an attribute that has no defined meaning?

> Regarding Windows, I'm not sure.  As far as I can see from the Lua
> sources, permission flags are directly derived from a stat() call.
> This means that they are related to the file owner too, not to the
> current user.

I suppose that we're only interested in the current user, so 
lfs.attributes should return the user's attributes. I was always under 
the impression that this was the case.

> If there is a file which is owned by the admin and is _not_ writable
> by normal users, does your test really return 'false' if run by a
> non-privileged user on Windows?

I don't know. Whatever we end up with it should be robust or at least 
predictable.

(i normally have only one account on computers and run everything as 
administrator or root)

Hans

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