Re: [PATCH] Added support for dropping privileges to git-daemon.

From: Marco Costalba <mcostalba@gmail.com>
Date: Aug 19, 2006, 15:19 UTC
Message-ID: <e5bfff550608190819i3cade548g28b2c95fab172a49@mail.gmail.com>
In-Reply-To: <20060819132922.GA6644@code-monkey.de>

On 8/19/06, Tilman Sauerbeck <tilman@code-monkey.de> wrote:

Show 14 quoted lines

> Marco Costalba [2006-08-19 15:23]:
> > >
> > >+       if (!user ^ !group)
> > >+               die("either set both user and group or none of them");
> > >+
> > >
> >
> > Just a  question. Why simply not
> >
> >       if (user ^ group)
>
> Because gcc doesn't like that:
>  error: invalid operands to binary ^
>

Interesting!

Indeed gcc it's right, operator ^ it's a bitwise operator, not a logical one. So operands must be booleans (or numerical types in case of C).

The trick is that operator '!' performs an implicit conversion to integral on the 'user' and 'group' pointers.

BTW the following (very ugly) works.

         if ((int)user ^ (int)group)