Re: [Caml-list] Re: Unix.getlogin () fails when stdin is redirected

[Yaron Minsky <yminsky@janestreet.com>]

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Looping in ocaml-core list.

On Tue, Mar 20, 2012 at 8:51 PM, Gerd Stolpmann <info@gerd-stolpmann.de>wrote:

>
> I second this. There is one OS where getlogin does not follow POSIX and is
> maybe insecure, and the fix cannot be to hide the function for all other
> OS. IMHO, these differences should be handled on a higher level, and not
> in the module providing the bindings.
>
> Semantically, there is a big difference between getlogin and getuid:
> getlogin shall also work when the user calls a setuid program which in
> turn invokes a script. These script commands can then use getlogin to
> identify the original user (which is defined as the user of the session =
> the user of the controlling terminal). In contrast, getuid would return
> the uid to which setuid switched (for the script).
>
> So, I'd say, you cannot repair getlogin with getuid. The best fix is
> probably to just run `/usr/bin/logname </dev/tty` and read the printed
> name.
>

I can think of a few solutions here:

   - We can use getuid only on platforms where getlogin is busted
   - We can name our function something other than "getlogin", to avoid
   confusion.
   - We can shell-out, in the way you suggest, to implement getlogin on
   Linux.  My only worry is that this is also going to be somewhat fragile in
   its own way.  Does calling out to logname with the suggested redirect
   always work?

I'm open to other suggestions.

y

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