[hackers] [quark] Fortify the sanity-checks || FRIGN

[git]

commit bd9d7e349346fd4664e134be1f8c5b162513b272
Author: FRIGN <d...@frign.de>
Date:   Thu Aug 14 17:48:37 2014 +0200

    Fortify the sanity-checks
    
    Hiltjo made a good start, but we need to check both the pointers
    and the first value to make sure that a NULL-pointer is not
    passed to the functions.

diff --git a/quark.c b/quark.c
index bae9808..27ec6a6 100644
--- a/quark.c
+++ b/quark.c
@@ -553,9 +553,9 @@ main(int argc, char *argv[]) {
        } ARGEND;
 
        /* sanity checks */
-       if (*user && !(upwd = getpwnam(user)))
+       if (user && *user && !(upwd = getpwnam(user)))
                die("error      invalid user %s
", user);
-       if (*group && !(gpwd = getgrnam(group)))
+       if (group && *group && !(gpwd = getgrnam(group)))
                die("error      invalid group %s
", group);
 
        signal(SIGCHLD, sighandler);