lib/PublicInbox/Admin.pm        | 11 +----------
 lib/PublicInbox/Config.pm       | 28 +++++++++++++++++++++++-----
 lib/PublicInbox/ExtSearchIdx.pm |  5 -----
 script/public-inbox-convert     |  2 +-
 script/public-inbox-init        |  2 +-

diff --git a/lib/PublicInbox/Admin.pm b/lib/PublicInbox/Admin.pm
index ea82133aa8adef38c994e528bf38649d4924bcf1..c972fb680a80da9b6ce5e9b0cf75c12a73fcf170 100644
--- a/lib/PublicInbox/Admin.pm
+++ b/lib/PublicInbox/Admin.pm
@@ -10,7 +10,7 @@ our @EXPORT_OK = qw(setup_signals);
 use PublicInbox::Config;
 use PublicInbox::Inbox;
 use PublicInbox::Spawn qw(popen_rd);
-use File::Spec ();
+*rel2abs_collapsed = \&PublicInbox::Config::rel2abs_collapsed;
 
 sub setup_signals {
 	my ($cb, $arg) = @_; # optional
@@ -25,15 +25,6 @@ 		eval { $cb->($sig, $arg) } if $cb;
 		$sig = 'SIG'.$sig;
 		exit(128 + POSIX->$sig);
 	};
-}
-
-# abs_path resolves symlinks, so we want to avoid it if rel2abs
-# is sufficient and doesn't leave "/.." or "/../"
-sub rel2abs_collapsed ($) {
-	my $p = File::Spec->rel2abs($_[0]);
-	return $p if substr($p, -3, 3) ne '/..' && index($p, '/../') < 0; # likely
-	require Cwd;
-	Cwd::abs_path($p);
 }
 
 sub resolve_inboxdir {
diff --git a/lib/PublicInbox/Config.pm b/lib/PublicInbox/Config.pm
index 2f5c83cd86c9f9322cca5a14120c6906c7cd73ea..577337dc8a024d375be2db4f72cffb0365be2ffb 100644
--- a/lib/PublicInbox/Config.pm
+++ b/lib/PublicInbox/Config.pm
@@ -368,6 +368,16 @@ 		undef;
 	}
 }
 
+# abs_path resolves symlinks, so we want to avoid it if rel2abs
+# is sufficient and doesn't leave "/.." or "/../"
+sub rel2abs_collapsed {
+	require File::Spec;
+	my $p = File::Spec->rel2abs($_[-1]);
+	return $p if substr($p, -3, 3) ne '/..' && index($p, '/../') < 0;
+	require Cwd;
+	Cwd::abs_path($p);
+}
+
 sub _fill {
 	my ($self, $pfx) = @_;
 	my $ibx = {};
@@ -391,9 +401,9 @@ 		}
 	}
 
 	# "mainrepo" is backwards compatibility:
-	$ibx->{inboxdir} //= $self->{"$pfx.mainrepo"} // return;
-	if ($ibx->{inboxdir} =~ /\n/s) {
-		warn "E: `$ibx->{inboxdir}' must not contain `\\n'\n";
+	my $dir = $ibx->{inboxdir} //= $self->{"$pfx.mainrepo"} // return;
+	if (index($dir, "\n") >= 0) {
+		warn "E: `$dir' must not contain `\\n'\n";
 		return;
 	}
 	foreach my $k (qw(obfuscate)) {
@@ -436,7 +446,7 @@ 		foreach my $list_id (@$listids) {
 			$self->{-by_list_id}->{lc($list_id)} = $ibx;
 		}
 	}
-	if (my $ngname = $ibx->{newsgroup}) {
+	if (defined(my $ngname = $ibx->{newsgroup})) {
 		if (ref($ngname)) {
 			delete $ibx->{newsgroup};
 			warn 'multiple newsgroups not supported: '.
@@ -445,13 +455,21 @@ 		# Newsgroup name needs to be compatible with RFC 3977
 		# wildmat-exact and RFC 3501 (IMAP) ATOM-CHAR.
 		# Leave out a few chars likely to cause problems or conflicts:
 		# '|', '<', '>', ';', '#', '$', '&',
-		} elsif ($ngname =~ m![^A-Za-z0-9/_\.\-\~\@\+\=:]!) {
+		} elsif ($ngname =~ m![^A-Za-z0-9/_\.\-\~\@\+\=:]! ||
+				$ngname eq '') {
 			delete $ibx->{newsgroup};
 			warn "newsgroup name invalid: `$ngname'\n";
 		} else {
 			# PublicInbox::NNTPD does stricter ->nntp_usable
 			# checks, keep this lean for startup speed
 			$self->{-by_newsgroup}->{$ngname} = $ibx;
+		}
+	}
+	unless (defined $ibx->{newsgroup}) { # for ->eidx_key
+		my $abs = rel2abs_collapsed($dir);
+		if ($abs ne $dir) {
+			warn "W: `$dir' canonicalized to `$abs'\n";
+			$ibx->{inboxdir} = $abs;
 		}
 	}
 	$self->{-by_name}->{$name} = $ibx;
diff --git a/lib/PublicInbox/ExtSearchIdx.pm b/lib/PublicInbox/ExtSearchIdx.pm
index b82d05462671500f97c4a04701804004bed1370c..c4b429df0cf8b5c8e71642d9e2d677837574d15e 100644
--- a/lib/PublicInbox/ExtSearchIdx.pm
+++ b/lib/PublicInbox/ExtSearchIdx.pm
@@ -72,11 +72,6 @@ 	if (!defined($ibx->uidvalidity)) {
 		warn "W: skipping $key (no UIDVALIDITY)\n";
 		return;
 	}
-	my $ibxdir = File::Spec->canonpath($ibx->{inboxdir});
-	if ($ibxdir ne $ibx->{inboxdir}) {
-		warn "W: `$ibx->{inboxdir}' canonicalized to `$ibxdir'\n";
-		$ibx->{inboxdir} = $ibxdir;
-	}
 	$self->{ibx_map}->{$key} //= do {
 		push @{$self->{ibx_list}}, $ibx;
 		$ibx;
diff --git a/script/public-inbox-convert b/script/public-inbox-convert
index fbd527a6a1bc187df3c3ebf511ff672a2378aed4..800c364cea4999352494249ce71691ccf023cc3b 100755
--- a/script/public-inbox-convert
+++ b/script/public-inbox-convert
@@ -75,7 +75,7 @@ 	$env = PublicInbox::Admin::index_prepare($opt, $cfg);
 }
 local %ENV = (%$env, %ENV) if $env;
 my $new = { %$old };
-$new->{inboxdir} = PublicInbox::Admin::rel2abs_collapsed($new_dir);
+$new->{inboxdir} = $cfg->rel2abs_collapsed($new_dir);
 $new->{version} = 2;
 $new = PublicInbox::InboxWritable->new($new, { nproc => $opt->{jobs} });
 $new->{-no_fsync} = 1 if !$opt->{fsync};
diff --git a/script/public-inbox-init b/script/public-inbox-init
index eb605a51221b2411e9a49e2154506f32ad9c54fc..afaa4c12978cadaee45d8284430c85c7a7ef7720 100755
--- a/script/public-inbox-init
+++ b/script/public-inbox-init
@@ -138,7 +138,7 @@
 my $pfx = "publicinbox.$name";
 my @x = (qw/git config/, "--file=$pi_config_tmp");
 
-PublicInbox::Admin::rel2abs_collapsed($inboxdir);
+PublicInbox::Config::rel2abs_collapsed($inboxdir);
 die "`\\n' not allowed in `$inboxdir'\n" if index($inboxdir, "\n") >= 0;
 
 if (-f "$inboxdir/inbox.lock") {