getpwent bug?

[Dan Nelson]

In the last episode (Jul 16), Ashish SHUKLA said:
> Dan Nelson writes:
> > In the last episode (Jul 15), Jens Rehsack said:
> >> Hi all,
> >> 
> >> I detected an issue with getpwent on my FreeBSD test box:
> >> 
> >> perl -MData::Dumper -e 'my @e = getpwent(); print Dumper(\@e); endpwent(); @e = getpwent(); print Dumper(\@e); endpwent(); @e = getpwent(); print Dumper(\@e); endpwent();'
> >> $VAR1 = [ 'root', '', 0, 0, 0, '', 'Charlie &', '/root', '/bin/csh', 0 ];
> >> $VAR1 = [ 'toor', '*', 0, 0, 0, '', 'Bourne-again Superuser', '/root', '', 0 ];
> >> $VAR1 = [ 'daemon', '*', 1, 1, 0, '', 'Owner of many system processes', '/root', '/usr/sbin/nologin', 0 ];
> >> 
> >> I'm using FreeBSD waldorf.muppets.liwing.de 7.3-PRERELEASE FreeBSD 7.3-PRERELEASE #0: Fri Mar 12 11:31:18 UTC 2010 root at waldorf.muppets.liwing.de:/usr/obj/usr/src/sys/WALDORF  amd64
> 
> > The above output looks perfect, and should match the top three lines in
> > /your etc/passwd files.
> 
> Well, OP is also invoking 'endpwent()' after every 'getpwent()' invocation
> which according to GNU/Linux's glibc and NetBSD's libc (as OP mentioned)
> should rewind the position in passwd database to the beginning.

Ah. I missed the endpwent calls.
 
> To me it definitely looks like a bug in FreeBSD's getpw*() family of
> functions.
> 
> As tested using sysutils/lsof, in the following program in FreeBSD, the
> descriptor corresponding to '/etc/pwd.db' is closed on endpwent(3) but
> position in database is never rewinded as shown in the output.

It looks like the *pwent functions keep an internal counter that endpwent
doesn't reset.  Try the following patch:

Index: gen/getpwent.c
===================================================================
--- gen/getpwent.c      (revision 210157)
+++ gen/getpwent.c      (working copy)
@@ -794,6 +794,7 @@ files_setpwent(void *retval, void *mdata, va_list
                        (void)st->db->close(st->db);
                        st->db = NULL;
                }
+               st->keynum = 0;
                break;
        default:
                break;
 

-- 
	Dan Nelson
	dnelson at allantgroup.com