Re: nss_db: protect against empty mappings

[Florian Weimer <fweimer at redhat dot com>]

* DJ Delorie:

> "Carlos O'Donell" <carlos@redhat.com> writes:
>> Merge the fixes then.
>
> Subject: nss_db: fix endent wrt NULL mappings
>
> nss_db allows for getpwent et al to be called without a set*ent,
> but it only works once.  After the last get*ent a set*ent is
> required to restart, because the end*ent did not properly reset
> the module.  Resetting it to NULL allows for a proper restart.
>
> If the database doesn't exist, however, end*ent erroniously called
> munmap which set errno.
>
> The test case runs "makedb" inside the testroot, so needs selinux
> DSOs installed.
>
> Resolves: #24695
> Resolves: #24696

You need to add “[BZ #24695]” or “bug 24695” to the commit message, the
above will not work.  If you can squeeze both numbers into the first
line, that's best.

> +  /* Before the fix, this would call munmap(NULL) and set errno.  */

Missing space before parenthesis.

> +  /* setpwent() is intentionally omitted here.  The first call to
> +     getpwent detects that it's first and initializes.  The second
> +     time try_it is called, this "first call" was not detected before
> +     the fix, and getpwent would crash.  */

GNU style is not to write () after function names.

> +  while ((pw = getpwent ()) != NULL)
> +    ;
> +
> +  endpwent ();

Would it be possible to add error checking here?

> +  system ("/usr/bin/makedb -o /var/db/passwd.db /var/db/passwd.in");

I think you need to use the actual installation path, not /usr/bin.

Thanks,
Florian