lib/PublicInbox/LeiMailSync.pm - pub/scm/infra/public-inbox - Git at Google

 # Copyright (C) all contributors <meta@public-inbox.org>
 # License: AGPL-3.0+ <https://www.gnu.org/licenses/agpl-3.0.txt>

 # for maintaining synchronization between lei/store <=> Maildir|MH|IMAP|JMAP
 package PublicInbox::LeiMailSync;
 use strict;
 use v5.10.1;
 use parent qw(PublicInbox::Lock);
 use PublicInbox::Compat qw(uniqstr);
 use DBI qw(:sql_types); # SQL_BLOB
 use PublicInbox::ContentHash qw(git_sha);
 use Carp ();
 use PublicInbox::Git qw(%HEXLEN2SHA);
 use PublicInbox::IO qw(read_all);

 sub dbh_new {
 	my ($self) = @_;
 	my $f = $self->{filename};
 	my $creat = !-s $f;
 	if ($creat) {
 		require PublicInbox::Syscall;
 		open my $fh, '+>>', $f or Carp::croak "open($f): $!";
 		PublicInbox::Syscall::nodatacow_fh($fh);
 	}
 	my $dbh = DBI->connect("dbi:SQLite:dbname=$f",'','', {
 		AutoCommit => 1,
 		RaiseError => 1,
 		PrintError => 0,
 		sqlite_use_immediate_transaction => 1,
 	});
 	# no sqlite_unicode, here, all strings are binary
 	create_tables($self, $dbh);
 	$dbh->do('PRAGMA journal_mode = WAL') if $creat;
 	$dbh->do('PRAGMA case_sensitive_like = ON');
 	$dbh;
 }

 sub new {
 	my ($cls, $f) = @_;
 	bless {
 		filename => $f,
 		fmap => {},
 		lock_path => "$f.flock",
 	}, $cls;
 }

 sub lms_write_prepare { ($_[0]->{dbh} //= dbh_new($_[0])); $_[0] }

 sub lms_pause {
 	my ($self) = @_;
 	$self->{fmap} = {};
 	my $dbh = delete $self->{dbh} // return;
 	eval { $dbh->do('PRAGMA optimize') };
 	warn 'W: optimize ', $dbh->sqlite_db_filename, ': ', $@ if $@;
 }

 sub create_tables {
 	my ($self, $dbh) = @_;
 	my $lk = $self->lock_for_scope;

 	$dbh->do(<<'');
 CREATE TABLE IF NOT EXISTS folders (
 	fid INTEGER PRIMARY KEY,
 	loc VARBINARY NOT NULL, /* URL;UIDVALIDITY=$N or $TYPE:/pathname */
 	UNIQUE (loc)
 )

 	$dbh->do(<<'');
 CREATE TABLE IF NOT EXISTS blob2num (
 	oidbin VARBINARY NOT NULL,
 	fid INTEGER NOT NULL, /* folder ID */
 	uid INTEGER NOT NULL, /* NNTP article number, IMAP UID, MH number */
 	/* not UNIQUE(fid, uid), since we may have broken servers */
 	UNIQUE (oidbin, fid, uid)
 )

 	# speeds up LeiImport->ck_update_kw (for "lei import") by 5-6x:
 	$dbh->do(<<'');
 CREATE INDEX IF NOT EXISTS idx_fid_uid ON blob2num(fid,uid)

 	$dbh->do(<<'');
 CREATE TABLE IF NOT EXISTS blob2name (
 	oidbin VARBINARY NOT NULL,
 	fid INTEGER NOT NULL, /* folder ID */
 	name VARBINARY NOT NULL, /* Maildir basename, JMAP blobId */
 	/* not UNIQUE(fid, name), since we may have broken software */
 	UNIQUE (oidbin, fid, name)
 )

 	# speeds up LeiImport->pmdir_cb (for "lei import") by ~6x:
 	$dbh->do(<<'');
 CREATE INDEX IF NOT EXISTS idx_fid_name ON blob2name(fid,name)

 }

 # used to fixup pre-1.7.0 folders
 sub update_fid ($$$) {
 	my ($dbh, $fid, $loc) = @_;
 	my $sth = $dbh->prepare(<<'');
 UPDATE folders SET loc = ? WHERE fid = ?

 	$sth->bind_param(1, $loc, SQL_BLOB);
 	$sth->bind_param(2, $fid);
 	$sth->execute;
 }

 sub get_fid ($$$) {
 	my ($sth, $folder, $dbh) = @_;
 	$sth->bind_param(1, $folder, SQL_BLOB);
 	$sth->execute;
 	my ($fid) = $sth->fetchrow_array;
 	if (defined $fid) { # for downgrade+upgrade (1.8 -> 1.7 -> 1.8)
 		my $del = $dbh->prepare_cached(<<'');
 DELETE FROM folders WHERE loc = ? AND fid != ?

 		$del->execute($folder, $fid);
 	} else {
 		$sth->bind_param(1, $folder, SQL_VARCHAR);
 		$sth->execute; # fixup old stuff
 		($fid) = $sth->fetchrow_array;
 		update_fid($dbh, $fid, $folder) if defined($fid);
 	}
 	$fid;
 }

 sub fid_for {
 	my ($self, $folder, $creat) = @_;
 	my $dbh = $self->{dbh} //= dbh_new($self);
 	my $sth = $dbh->prepare_cached(<<'', undef, 1);
 SELECT fid FROM folders WHERE loc = ? LIMIT 1

 	my $fid = get_fid($sth, $folder, $dbh);
 	return $fid if defined($fid);

 	# caller had trailing slash (LeiToMail)
 	if ($folder =~ s!\A((?:maildir|mh):.*?)/+\z!$1!i) {
 		$fid = get_fid($sth, $folder, $dbh);
 		if (defined $fid) {
 			update_fid($dbh, $fid, $folder);
 			return $fid;
 		}
 	# sometimes we stored trailing slash..
 	} elsif ($folder =~ m!\A(?:maildir|mh):!i) {
 		$fid = get_fid($sth, $folder, $dbh);
 		if (defined $fid) {
 			update_fid($dbh, $fid, $folder);
 			return $fid;
 		}
 	} elsif ($creat && $folder =~ m!\Aimaps?://!i) {
 		require PublicInbox::URIimap;
 		my $uri = PublicInbox::URIimap->new($folder);
 		$uri->uidvalidity //
 			Carp::croak("BUG: $folder has no UIDVALIDITY");
 		defined($uri->uid) and Carp::confess("BUG: $folder has UID");
 	}

 	return unless $creat;
 	($fid) = $dbh->selectrow_array('SELECT MAX(fid) FROM folders');

 	$fid += 1;
 	# in case we're reusing, clobber existing stale refs:
 	$dbh->do('DELETE FROM blob2name WHERE fid = ?', undef, $fid);
 	$dbh->do('DELETE FROM blob2num WHERE fid = ?', undef, $fid);

 	$sth = $dbh->prepare('INSERT INTO folders (fid, loc) VALUES (?, ?)');
 	$sth->bind_param(1, $fid);
 	$sth->bind_param(2, $folder, SQL_BLOB);
 	$sth->execute;

 	$fid;
 }

 sub add_folders {
 	my ($self, @folders) = @_;
 	my $lk = $self->lock_for_scope;
 	for my $f (@folders) { $self->{fmap}->{$f} //= fid_for($self, $f, 1) }
 }

 sub set_src {
 	my ($self, $oidbin, $folder, $id) = @_;
 	my $lk = $self->lock_for_scope;
 	my $fid = $self->{fmap}->{$folder} //= fid_for($self, $folder, 1);
 	my $dbh = $self->{dbh};
 	my ($sth, @param3, $del_old);
 	if (ref($id)) { # scalar name
 		@param3 = ($$id, SQL_BLOB);
 		$sth = $dbh->prepare_cached(<<'');
 INSERT OR IGNORE INTO blob2name (oidbin, fid, name) VALUES (?, ?, ?)

 		$del_old = $dbh->prepare_cached(<<'');
 DELETE FROM blob2name WHERE oidbin = ? AND fid = ? AND name = ?

 	} else { # numeric ID (IMAP UID, MH number)
 		@param3 = ($id);
 		$sth = $dbh->prepare_cached(<<'');
 INSERT OR IGNORE INTO blob2num (oidbin, fid, uid) VALUES (?, ?, ?)

 		$del_old = $dbh->prepare_cached(<<'');
 DELETE FROM blob2num WHERE oidbin = ? AND fid = ? AND uid = ?

 	}
 	$sth->bind_param(1, $oidbin, SQL_BLOB);
 	$sth->bind_param(2, $fid);
 	$sth->bind_param(3, @param3);
 	my $ret = $sth->execute;
 	$del_old->execute($oidbin, $fid, $param3[0]);
 	$ret;
 }

 sub clear_src {
 	my ($self, $folder, $id) = @_;
 	my $lk = $self->lock_for_scope;
 	my $fid = $self->{fmap}->{$folder} //= fid_for($self, $folder, 1);
 	my ($sth, @param3);
 	if (ref($id)) { # scalar name
 		@param3 = ($$id, SQL_BLOB);
 		$sth = $self->{dbh}->prepare_cached(<<'');
 DELETE FROM blob2name WHERE fid = ? AND name = ?

 	} else {
 		@param3 = ($id);
 		$sth = $self->{dbh}->prepare_cached(<<'');
 DELETE FROM blob2num WHERE fid = ? AND uid = ?

 	}
 	$sth->bind_param(1, $fid);
 	$sth->bind_param(2, @param3);
 	my $ret = $sth->execute;

 	# older versions may not have used SQL_BLOB:
 	if (defined($ret) && $ret == 0 && scalar(@param3) == 2) {
 		$sth->bind_param(1, $fid);
 		$sth->bind_param(2, $param3[0]);
 		$ret = $sth->execute;
 	}
 	$ret;
 }

 # Maildir-only
 sub mv_src {
 	my ($self, $folder, $oidbin, $id, $newbn) = @_;
 	my $lk = $self->lock_for_scope;
 	my $fid = $self->{fmap}->{$folder} //= fid_for($self, $folder, 1);
 	$self->{dbh}->begin_work;
 	my $sth = $self->{dbh}->prepare_cached(<<'');
 UPDATE blob2name SET name = ? WHERE fid = ? AND oidbin = ? AND name = ?

 	# eval since unique constraint may fail due to race
 	$sth->bind_param(1, $newbn, SQL_BLOB);
 	$sth->bind_param(2, $fid);
 	$sth->bind_param(3, $oidbin, SQL_BLOB);
 	$sth->bind_param(4, $$id, SQL_BLOB);
 	my $nr = eval { $sth->execute };
 	if (!defined($nr) || $nr == 0) { # $nr may be `0E0'
 		# delete from old, pre-SQL_BLOB rows:
 		my $del_old = $self->{dbh}->prepare_cached(<<'');
 DELETE FROM blob2name WHERE fid = ? AND oidbin = ? AND name = ?

 		$del_old->execute($fid, $oidbin, $$id); # missing-OK
 		$del_old->execute($fid, $oidbin, $newbn); # ditto

 		# may race with a clear_src, ensure new value exists
 		$sth = $self->{dbh}->prepare_cached(<<'');
 INSERT OR IGNORE INTO blob2name (oidbin, fid, name) VALUES (?, ?, ?)

 		$sth->bind_param(1, $oidbin, SQL_BLOB);
 		$sth->bind_param(2, $fid);
 		$sth->bind_param(3, $newbn, SQL_BLOB);
 		$sth->execute;
 	}
 	$self->{dbh}->commit;
 }

 # read-only, iterates every oidbin + UID or name for a given folder
 sub each_src {
 	my ($self, $folder, $cb, @args) = @_;
 	my $dbh = $self->{dbh} //= dbh_new($self);
 	my ($fid, @rng);
 	my $and_ge_le = '';
 	if (ref($folder) eq 'HASH') {
 		$fid = $folder->{fid} // die "BUG: no `fid'";
 		@rng = grep(defined, @$folder{qw(min max)});
 		$and_ge_le = 'AND uid >= ? AND uid <= ?' if @rng;
 	} else {
 		$fid = $self->{fmap}->{$folder} //=
 			fid_for($self, $folder) // return;
 	}

 	# minimize implicit txn time to avoid blocking writers by
 	# batching SELECTs.  This looks wonky but is necessary since
 	# $cb-> may access the DB on its own.
 	my $ary = $dbh->selectall_arrayref(<<"", undef, $fid, @rng);
 SELECT _rowid_,oidbin,uid FROM blob2num WHERE fid = ? $and_ge_le
 ORDER BY _rowid_ ASC LIMIT 1000

 	my $min = @$ary ? $ary->[-1]->[0] : undef;
 	while (defined $min) {
 		for my $row (@$ary) { $cb->($row->[1], $row->[2], @args) }

 		$ary = $dbh->selectall_arrayref(<<"", undef, $fid, @rng, $min);
 SELECT _rowid_,oidbin,uid FROM blob2num
 WHERE fid = ? $and_ge_le AND _rowid_ > ?
 ORDER BY _rowid_ ASC LIMIT 1000

 		$min = @$ary ? $ary->[-1]->[0] : undef;
 	}

 	$ary = $dbh->selectall_arrayref(<<'', undef, $fid);
 SELECT _rowid_,oidbin,name FROM blob2name WHERE fid = ?
 ORDER BY _rowid_ ASC LIMIT 1000

 	$min = @$ary ? $ary->[-1]->[0] : undef;
 	while (defined $min) {
 		for my $row (@$ary) { $cb->($row->[1], \($row->[2]), @args) }

 		$ary = $dbh->selectall_arrayref(<<'', undef, $fid, $min);
 SELECT _rowid_,oidbin,name FROM blob2name WHERE fid = ? AND _rowid_ > ?
 ORDER BY _rowid_ ASC LIMIT 1000

 		$min = @$ary ? $ary->[-1]->[0] : undef;
 	}
 }

 sub location_stats {
 	my ($self, $folder) = @_;
 	my $dbh = $self->{dbh} //= dbh_new($self);
 	my $fid;
 	my $ret = {};
 	$fid = $self->{fmap}->{$folder} //= fid_for($self, $folder) // return;
 	my ($row) = $dbh->selectrow_array(<<"", undef, $fid);
 SELECT COUNT(name) FROM blob2name WHERE fid = ?

 	$ret->{'name.count'} = $row if $row;
 	my $ntype = ($folder =~ m!\A(?:nntps?|s?news)://!i) ? 'article' :
 		(($folder =~ m!\Aimaps?://!i) ? 'uid' : "TODO<$folder>");
 	for my $op (qw(count min max)) {
 		($row) = $dbh->selectrow_array(<<"", undef, $fid);
 SELECT $op(uid) FROM blob2num WHERE fid = ?

 		$row or last;
 		$ret->{"$ntype.$op"} = $row;
 	}
 	$ret;
 }

 # must be called with lock
 sub _forget_fids ($;@) {
 	my $dbh = shift;
 	$dbh->begin_work;
 	for my $t (qw(blob2name blob2num folders)) {
 		my $sth = $dbh->prepare_cached("DELETE FROM $t WHERE fid = ?");
 		$sth->execute($_) for @_;
 	}
 	$dbh->commit;
 }

 # returns a { location => [ list-of-ids-or-names ] } mapping
 sub locations_for {
 	my ($self, $oidbin) = @_;
 	my ($fid, $sth, $id, %fid2id, %seen);
 	my $dbh = $self->{dbh} //= dbh_new($self);
 	$sth = $dbh->prepare('SELECT fid,uid FROM blob2num WHERE oidbin = ?');
 	$sth->bind_param(1, $oidbin, SQL_BLOB);
 	$sth->execute;
 	while (my ($fid, $uid) = $sth->fetchrow_array) {
 		push @{$fid2id{$fid}}, $uid;
 		$seen{"$uid.$fid"} = 1;
 	}

 	# deal with 1.7.0 DBs :<
 	$sth->bind_param(1, $oidbin, SQL_VARCHAR);
 	$sth->execute;
 	while (my ($fid, $uid) = $sth->fetchrow_array) {
 		next if $seen{"$uid.$fid"};
 		push @{$fid2id{$fid}}, $uid;
 	}

 	%seen = ();
 	$sth = $dbh->prepare('SELECT fid,name FROM blob2name WHERE oidbin = ?');
 	$sth->bind_param(1, $oidbin, SQL_BLOB);
 	$sth->execute;
 	while (my ($fid, $name) = $sth->fetchrow_array) {
 		push @{$fid2id{$fid}}, $name;
 		$seen{"$fid.$name"} = 1;
 	}

 	# deal with 1.7.0 DBs :<
 	$sth->bind_param(1, $oidbin, SQL_VARCHAR);
 	$sth->execute;
 	while (my ($fid, $name) = $sth->fetchrow_array) {
 		next if $seen{"$fid.$name"};
 		push @{$fid2id{$fid}}, $name;
 	}

 	$sth = $dbh->prepare('SELECT loc FROM folders WHERE fid = ? LIMIT 1');
 	my $ret = {};
 	my $drop_fids = $dbh->{ReadOnly} ? undef : {};
 	while (my ($fid, $ids) = each %fid2id) {
 		$sth->execute($fid);
 		my ($loc) = $sth->fetchrow_array;
 		unless (defined $loc) {
 			my $del = '';
 			if ($drop_fids) {
 				$del = ' (deleting)';
 				$drop_fids->{$fid} = $fid;
 			}
 			my $oidhex = unpack('H*', $oidbin);
 			warn "E: fid=$fid for $oidhex stale/unknown:\n", map {
 					'E: '.(ref() ? $$_ : "#$_")."$del\n";
 				} @$ids;
 			next;
 		}
 		$ret->{$loc} = $ids;
 	}
 	if ($drop_fids && scalar(values %$drop_fids)) {
 		my $lk = $self->lock_for_scope;
 		_forget_fids($self->{dbh}, values %$drop_fids);
 	}
 	scalar(keys %$ret) ? $ret : undef;
 }

 # returns a list of folders used for completion
 sub folders {
 	my ($self, @pfx) = @_;
 	my $sql = 'SELECT loc FROM folders';
 	my $re;
 	if (defined($pfx[0])) {
 		$sql .= ' WHERE loc REGEXP ?'; # DBD::SQLite uses perlre
 		if (ref($pfx[0])) { # assume qr// "Regexp"
 			$re = $pfx[0];
 		} else {
 			$re = !!$pfx[1] ? '.*' : '';
 			$re .= quotemeta($pfx[0]);
 			$re .= '.*';
 		}
 	}
 	my $sth = ($self->{dbh} //= dbh_new($self))->prepare($sql);
 	$sth->bind_param(1, $re) if defined($re);
 	$sth->execute;
 	map { $_->[0] } @{$sth->fetchall_arrayref};
 }

 sub blob_mismatch ($$$) {
 	my ($f, $oidhex, $rawref) = @_;
 	my $sha = $HEXLEN2SHA{length($oidhex)};
 	my $got = git_sha($sha, $rawref)->hexdigest;
 	$got eq $oidhex ? undef : warn("$f changed $oidhex => $got\n");
 }

 sub local_blob {
 	my ($self, $oidhex, $vrfy) = @_;
 	my $dbh = $self->{dbh} //= dbh_new($self);
 	my $oidbin = pack('H*', $oidhex);

 	my $b2n = $dbh->prepare(<<'');
 SELECT f.loc,b.name FROM blob2name b
 LEFT JOIN folders f ON b.fid = f.fid
 WHERE b.oidbin = ?

 	$b2n->bind_param(1, $oidbin, SQL_BLOB);
 	$b2n->execute;
 	while (my ($d, $n) = $b2n->fetchrow_array) {
 		substr($d, 0, length('maildir:')) = '';
 		# n.b. both mbsync and offlineimap use ":2," as a suffix
 		# in "new/", despite (from what I understand of reading
 		# <https://cr.yp.to/proto/maildir.html>), the ":2," only
 		# applies to files in "cur/".
 		my @try = $n =~ /:2,[a-zA-Z]+\z/ ? qw(cur new) : qw(new cur);
 		for my $x (@try) {
 			my $f = "$d/$x/$n";
 			open my $fh, '<', $f or next;
 			# some (buggy) Maildir writers are non-atomic:
 			my $raw = read_all($fh, -s $fh // next);
 			next if $vrfy && blob_mismatch $f, $oidhex, \$raw;
 			return \$raw;
 		}
 	}

 	# MH, except `uid' is not always unique (can be packed)
 	$b2n = $dbh->prepare(<<'');
 SELECT f.loc,b.uid FROM blob2num b
 LEFT JOIN folders f ON b.fid = f.fid
 WHERE b.oidbin = ? AND f.loc REGEXP '^mh:/'

 	$b2n->bind_param(1, $oidbin, SQL_BLOB);
 	$b2n->execute;
 	while (my ($f, $n) = $b2n->fetchrow_array) {
 		$f =~ s/\Amh://s or die "BUG: not MH: $f";
 		$f .= "/$n";
 		open my $fh, '<', $f or next;
 		my $raw = read_all($fh, -s $fh // next);
 		next if blob_mismatch $f, $oidhex, \$raw;
 		return \$raw;
 	}
 	undef;
 }

 sub match_imap_url {
 	my ($self, $url, $all) = @_; # $all = [ $lms->folders ];
 	$all //= [ $self->folders ];
 	require PublicInbox::URIimap;
 	my $want = PublicInbox::URIimap->new($url)->canonical;
 	my ($s, $h, $mb) = ($want->scheme, $want->host, $want->mailbox);
 	my @uri = map { PublicInbox::URIimap->new($_)->canonical }
 		grep(m!\A\Q$s\E://.*?\Q$h\E\b.*?/\Q$mb\E\b!, @$all);
 	my @match;
 	for my $x (@uri) {
 		next if $x->mailbox ne $want->mailbox;
 		next if $x->host ne $want->host;
 		next if $x->port != $want->port;
 		my $x_uidval = $x->uidvalidity;
 		next if ($want->uidvalidity // $x_uidval) != $x_uidval;

 		# allow nothing in want to possibly match ";AUTH=ANONYMOUS"
 		if (defined($x->auth) && !defined($want->auth) &&
 				!defined($want->user)) {
 			push @match, $x;
 		# or maybe user was forgotten on CLI:
 		} elsif (defined($x->user) && !defined($want->user)) {
 			push @match, $x;
 		} elsif (($x->user//"\0") eq ($want->user//"\0")) {
 			push @match, $x;
 		}
 	}
 	return @match if wantarray;
 	scalar(@match) <= 1 ? $match[0] :
 			"E: `$url' is ambiguous:\n\t".join("\n\t", @match)."\n";
 }

 sub match_nntp_url ($$$) {
 	my ($self, $url, $all) = @_; # $all = [ $lms->folders ];
 	$all //= [ $self->folders ];
 	require PublicInbox::URInntps;
 	my $want = PublicInbox::URInntps->new($url)->canonical;
 	my ($s, $h, $p) = ($want->scheme, $want->host, $want->port);
 	my $ng = $want->group; # force scalar (no article ranges)
 	my @uri = map { PublicInbox::URInntps->new($_)->canonical }
 		grep(m!\A\Q$s\E://.*?\Q$h\E\b.*?/\Q$ng\E\b!, @$all);
 	my @match;
 	for my $x (@uri) {
 		next if $x->group ne $ng || $x->host ne $h || $x->port != $p;
 		# maybe user was forgotten on CLI:
 		if (defined($x->userinfo) && !defined($want->userinfo)) {
 			push @match, $x;
 		} elsif (($x->userinfo//"\0") eq ($want->userinfo//"\0")) {
 			push @match, $x;
 		}
 	}
 	return @match if wantarray;
 	scalar(@match) <= 1 ? $match[0] :
 			"E: `$url' is ambiguous:\n\t".join("\n\t", @match)."\n";
 }

 # returns undef on failure, number on success
 sub group2folders {
 	my ($self, $lei, $all, $folders) = @_;
 	return $lei->fail(<<EOM) if @$folders;
 --all= not compatible with @$folders on command-line
 EOM
 	my %x = map { $_ => $_ } split(/,/, $all);
 	my @ok = grep(defined, delete(@x{qw(local remote), ''}));
 	push(@ok, '') if $all eq '';
 	my @no = keys %x;
 	if (@no) {
 		@no = (join(',', @no));
 		return $lei->fail(<<EOM);
 --all=@no not accepted (must be `local' and/or `remote')
 EOM
 	}
 	my @all = $self->folders;
 	for my $ok (@ok) {
 		if ($ok eq 'local') {
 			push @$folders, grep(!m!\A[a-z0-9\+]+://!i, @all);
 		} elsif ($ok eq 'remote') {
 			push @$folders, grep(m!\A[a-z0-9\+]+://!i, @all);
 		} elsif ($ok ne '') {
 			return $lei->fail("--all=$all not understood");
 		} else {
 			push @$folders, @all;
 		}
 	}
 	@$folders = uniqstr @$folders;
 	scalar(@$folders) || $lei->fail(<<EOM);
 no --mail-sync folders known to lei
 EOM
 }

 # map CLI args to folder table entries, returns undef on failure
 sub arg2folder {
 	my ($self, $lei, $folders) = @_;
 	my @all = $self->folders;
 	my %all = map { $_ => 1 } @all;
 	my @no;
 	for (@$folders) {
 		next if $all{$_}; # ok
 		if (m!\A(maildir|mh):(.+)!i) {
 			my $type = lc $1;
 			my $d = "$type:".$lei->abs_path($2);
 			push(@no, $_) unless $all{$d};
 			$_ = $d;
 		} elsif (-d "$_/new" && -d "$_/cur") {
 			my $d = 'maildir:'.$lei->abs_path($_);
 			push(@no, $_) unless $all{$d};
 			$_ = $d;
 		} elsif (m!\Aimaps?://!i) {
 			my $orig = $_;
 			my $res = match_imap_url($self, $orig, \@all);
 			if (ref $res) {
 				$_ = $$res;
 				$lei->qerr(<<EOM);
 # using `$res' instead of `$orig'
 EOM
 			} else {
 				warn($res, "\n") if defined $res;
 				push @no, $orig;
 			}
 		} elsif (m!\A(?:nntps?|s?news)://!i) {
 			my $orig = $_;
 			my $res = match_nntp_url($self, $orig, \@all);
 			if (ref $res) {
 				$_ = $$res;
 				$lei->qerr(<<EOM);
 # using `$res' instead of `$orig'
 EOM
 			} else {
 				warn($res, "\n") if defined $res;
 				push @no, $orig;
 			}
 		} else {
 			push @no, $_;
 		}
 	}
 	if (@no) {
 		my $no = join("\n\t", @no);
 		die <<EOF;
 No sync information for: $no
 Run `lei ls-mail-sync' to display valid choices
 EOF
 	}
 }

 sub forget_folders {
 	my ($self, @folders) = @_;
 	my $lk = $self->lock_for_scope;
 	_forget_fids($self->{dbh}, map {
 		delete($self->{fmap}->{$_}) //
 			fid_for($self, $_) // ();
 	} @folders);
 }

 # only used for changing canonicalization errors
 sub rename_folder {
 	my ($self, $old, $new) = @_;
 	my $lk = $self->lock_for_scope;
 	my $ofid = delete($self->{fmap}->{$old}) //
 		fid_for($self, $old) // return;
 	eval {
 		$self->{dbh}->do(<<EOM, undef, $new, $ofid);
 UPDATE folders SET loc = ? WHERE fid = ?
 EOM
 	};
 	if ($@ =~ /\bunique\b/i) {
 		my $nfid = $self->{fmap}->{$new} // fid_for($self, $new);
 		for my $t (qw(blob2name blob2num)) {
 			$self->{dbh}->do(<<EOM, undef, $nfid, $ofid);
 UPDATE OR REPLACE $t SET fid = ? WHERE fid = ?
 EOM
 		}
 		$self->{dbh}->do(<<EOM, undef, $ofid);
 DELETE FROM folders WHERE fid = ?
 EOM
 	}
 }

 sub num_oidbin ($$$) {
 	my ($self, $url, $uid) = @_; # $url MUST have UIDVALIDITY if IMAP
 	my $fid = $self->{fmap}->{$url} //= fid_for($self, $url) // return ();
 	my $sth = $self->{dbh}->prepare_cached(<<EOM, undef, 1);
 SELECT oidbin FROM blob2num WHERE fid = ? AND uid = ? ORDER BY _rowid_
 EOM
 	$sth->execute($fid, $uid);
 	# for public-inbox <= 1.7.0:
 	uniqstr(map { $_->[0] } @{$sth->fetchall_arrayref});
 }

 sub name_oidbin ($$$) {
 	my ($self, $mdir, $nm) = @_;
 	my $fid = $self->{fmap}->{$mdir} //= fid_for($self, $mdir) // return;
 	my $sth = $self->{dbh}->prepare_cached(<<EOM, undef, 1);
 SELECT oidbin FROM blob2name WHERE fid = ? AND name = ?
 EOM
 	$sth->bind_param(1, $fid);
 	$sth->bind_param(2, $nm, SQL_BLOB);
 	$sth->execute;
 	my @bin = map { $_->[0] } @{$sth->fetchall_arrayref};
 	$sth->bind_param(1, $fid);
 	$sth->bind_param(2, $nm, SQL_VARCHAR);
 	$sth->execute;
 	my @old = map { $_->[0] } @{$sth->fetchall_arrayref};
 	uniqstr @bin, @old # for public-inbox <= 1.7.0
 }

 sub imap_oidhex {
 	my ($self, $lei, $uid_uri) = @_;
 	my $mailbox_uri = $uid_uri->clone;
 	$mailbox_uri->uid(undef);
 	my $folders = [ $$mailbox_uri ];
 	eval { $self->arg2folder($lei, $folders) };
 	$lei->qerr("# no sync information for $mailbox_uri") if $@;
 	map { unpack('H*',$_) } num_oidbin($self, $folders->[0], $uid_uri->uid)
 }

 1;
	# Copyright (C) all contributors <meta@public-inbox.org>
	# License: AGPL-3.0+ <https://www.gnu.org/licenses/agpl-3.0.txt>

	# for maintaining synchronization between lei/store <=> Maildir\|MH\|IMAP\|JMAP
	package PublicInbox::LeiMailSync;
	use strict;
	use v5.10.1;
	use parent qw(PublicInbox::Lock);
	use PublicInbox::Compat qw(uniqstr);
	use DBI qw(:sql_types); # SQL_BLOB
	use PublicInbox::ContentHash qw(git_sha);
	use Carp ();
	use PublicInbox::Git qw(%HEXLEN2SHA);
	use PublicInbox::IO qw(read_all);

	sub dbh_new {
	my ($self) = @_;
	my $f = $self->{filename};
	my $creat = !-s $f;
	if ($creat) {
	require PublicInbox::Syscall;
	open my $fh, '+>>', $f or Carp::croak "open($f): $!";
	PublicInbox::Syscall::nodatacow_fh($fh);
	}
	my $dbh = DBI->connect("dbi:SQLite:dbname=$f",'','', {
	AutoCommit => 1,
	RaiseError => 1,
	PrintError => 0,
	sqlite_use_immediate_transaction => 1,
	});
	# no sqlite_unicode, here, all strings are binary
	create_tables($self, $dbh);
	$dbh->do('PRAGMA journal_mode = WAL') if $creat;
	$dbh->do('PRAGMA case_sensitive_like = ON');
	$dbh;
	}

	sub new {
	my ($cls, $f) = @_;
	bless {
	filename => $f,
	fmap => {},
	lock_path => "$f.flock",
	}, $cls;
	}

	sub lms_write_prepare { ($_[0]->{dbh} //= dbh_new($_[0])); $_[0] }

	sub lms_pause {
	my ($self) = @_;
	$self->{fmap} = {};
	my $dbh = delete $self->{dbh} // return;
	eval { $dbh->do('PRAGMA optimize') };
	warn 'W: optimize ', $dbh->sqlite_db_filename, ': ', $@ if $@;
	}

	sub create_tables {
	my ($self, $dbh) = @_;
	my $lk = $self->lock_for_scope;

	$dbh->do(<<'');
	CREATE TABLE IF NOT EXISTS folders (
	fid INTEGER PRIMARY KEY,
	loc VARBINARY NOT NULL, /* URL;UIDVALIDITY=$N or $TYPE:/pathname */
	UNIQUE (loc)
	)

	$dbh->do(<<'');
	CREATE TABLE IF NOT EXISTS blob2num (
	oidbin VARBINARY NOT NULL,
	fid INTEGER NOT NULL, /* folder ID */
	uid INTEGER NOT NULL, /* NNTP article number, IMAP UID, MH number */
	/* not UNIQUE(fid, uid), since we may have broken servers */
	UNIQUE (oidbin, fid, uid)
	)

	# speeds up LeiImport->ck_update_kw (for "lei import") by 5-6x:
	$dbh->do(<<'');
	CREATE INDEX IF NOT EXISTS idx_fid_uid ON blob2num(fid,uid)

	$dbh->do(<<'');
	CREATE TABLE IF NOT EXISTS blob2name (
	oidbin VARBINARY NOT NULL,
	fid INTEGER NOT NULL, /* folder ID */
	name VARBINARY NOT NULL, /* Maildir basename, JMAP blobId */
	/* not UNIQUE(fid, name), since we may have broken software */
	UNIQUE (oidbin, fid, name)
	)

	# speeds up LeiImport->pmdir_cb (for "lei import") by ~6x:
	$dbh->do(<<'');
	CREATE INDEX IF NOT EXISTS idx_fid_name ON blob2name(fid,name)

	}

	# used to fixup pre-1.7.0 folders
	sub update_fid ($$$) {
	my ($dbh, $fid, $loc) = @_;
	my $sth = $dbh->prepare(<<'');
	UPDATE folders SET loc = ? WHERE fid = ?

	$sth->bind_param(1, $loc, SQL_BLOB);
	$sth->bind_param(2, $fid);
	$sth->execute;
	}

	sub get_fid ($$$) {
	my ($sth, $folder, $dbh) = @_;
	$sth->bind_param(1, $folder, SQL_BLOB);
	$sth->execute;
	my ($fid) = $sth->fetchrow_array;
	if (defined $fid) { # for downgrade+upgrade (1.8 -> 1.7 -> 1.8)
	my $del = $dbh->prepare_cached(<<'');
	DELETE FROM folders WHERE loc = ? AND fid != ?

	$del->execute($folder, $fid);
	} else {
	$sth->bind_param(1, $folder, SQL_VARCHAR);
	$sth->execute; # fixup old stuff
	($fid) = $sth->fetchrow_array;
	update_fid($dbh, $fid, $folder) if defined($fid);
	}
	$fid;
	}

	sub fid_for {
	my ($self, $folder, $creat) = @_;
	my $dbh = $self->{dbh} //= dbh_new($self);
	my $sth = $dbh->prepare_cached(<<'', undef, 1);
	SELECT fid FROM folders WHERE loc = ? LIMIT 1

	my $fid = get_fid($sth, $folder, $dbh);
	return $fid if defined($fid);

	# caller had trailing slash (LeiToMail)
	if ($folder =~ s!\A((?:maildir\|mh):.*?)/+\z!$1!i) {
	$fid = get_fid($sth, $folder, $dbh);
	if (defined $fid) {
	update_fid($dbh, $fid, $folder);
	return $fid;
	}
	# sometimes we stored trailing slash..
	} elsif ($folder =~ m!\A(?:maildir\|mh):!i) {
	$fid = get_fid($sth, $folder, $dbh);
	if (defined $fid) {
	update_fid($dbh, $fid, $folder);
	return $fid;
	}
	} elsif ($creat && $folder =~ m!\Aimaps?://!i) {
	require PublicInbox::URIimap;
	my $uri = PublicInbox::URIimap->new($folder);
	$uri->uidvalidity //
	Carp::croak("BUG: $folder has no UIDVALIDITY");
	defined($uri->uid) and Carp::confess("BUG: $folder has UID");
	}

	return unless $creat;
	($fid) = $dbh->selectrow_array('SELECT MAX(fid) FROM folders');

	$fid += 1;
	# in case we're reusing, clobber existing stale refs:
	$dbh->do('DELETE FROM blob2name WHERE fid = ?', undef, $fid);
	$dbh->do('DELETE FROM blob2num WHERE fid = ?', undef, $fid);

	$sth = $dbh->prepare('INSERT INTO folders (fid, loc) VALUES (?, ?)');
	$sth->bind_param(1, $fid);
	$sth->bind_param(2, $folder, SQL_BLOB);
	$sth->execute;

	$fid;
	}

	sub add_folders {
	my ($self, @folders) = @_;
	my $lk = $self->lock_for_scope;
	for my $f (@folders) { $self->{fmap}->{$f} //= fid_for($self, $f, 1) }
	}

	sub set_src {
	my ($self, $oidbin, $folder, $id) = @_;
	my $lk = $self->lock_for_scope;
	my $fid = $self->{fmap}->{$folder} //= fid_for($self, $folder, 1);
	my $dbh = $self->{dbh};
	my ($sth, @param3, $del_old);
	if (ref($id)) { # scalar name
	@param3 = ($$id, SQL_BLOB);
	$sth = $dbh->prepare_cached(<<'');
	INSERT OR IGNORE INTO blob2name (oidbin, fid, name) VALUES (?, ?, ?)

	$del_old = $dbh->prepare_cached(<<'');
	DELETE FROM blob2name WHERE oidbin = ? AND fid = ? AND name = ?

	} else { # numeric ID (IMAP UID, MH number)
	@param3 = ($id);
	$sth = $dbh->prepare_cached(<<'');
	INSERT OR IGNORE INTO blob2num (oidbin, fid, uid) VALUES (?, ?, ?)

	$del_old = $dbh->prepare_cached(<<'');
	DELETE FROM blob2num WHERE oidbin = ? AND fid = ? AND uid = ?

	}
	$sth->bind_param(1, $oidbin, SQL_BLOB);
	$sth->bind_param(2, $fid);
	$sth->bind_param(3, @param3);
	my $ret = $sth->execute;
	$del_old->execute($oidbin, $fid, $param3[0]);
	$ret;
	}

	sub clear_src {
	my ($self, $folder, $id) = @_;
	my $lk = $self->lock_for_scope;
	my $fid = $self->{fmap}->{$folder} //= fid_for($self, $folder, 1);
	my ($sth, @param3);
	if (ref($id)) { # scalar name
	@param3 = ($$id, SQL_BLOB);
	$sth = $self->{dbh}->prepare_cached(<<'');
	DELETE FROM blob2name WHERE fid = ? AND name = ?

	} else {
	@param3 = ($id);
	$sth = $self->{dbh}->prepare_cached(<<'');
	DELETE FROM blob2num WHERE fid = ? AND uid = ?

	}
	$sth->bind_param(1, $fid);
	$sth->bind_param(2, @param3);
	my $ret = $sth->execute;

	# older versions may not have used SQL_BLOB:
	if (defined($ret) && $ret == 0 && scalar(@param3) == 2) {
	$sth->bind_param(1, $fid);
	$sth->bind_param(2, $param3[0]);
	$ret = $sth->execute;
	}
	$ret;
	}

	# Maildir-only
	sub mv_src {
	my ($self, $folder, $oidbin, $id, $newbn) = @_;
	my $lk = $self->lock_for_scope;
	my $fid = $self->{fmap}->{$folder} //= fid_for($self, $folder, 1);
	$self->{dbh}->begin_work;
	my $sth = $self->{dbh}->prepare_cached(<<'');
	UPDATE blob2name SET name = ? WHERE fid = ? AND oidbin = ? AND name = ?

	# eval since unique constraint may fail due to race
	$sth->bind_param(1, $newbn, SQL_BLOB);
	$sth->bind_param(2, $fid);
	$sth->bind_param(3, $oidbin, SQL_BLOB);
	$sth->bind_param(4, $$id, SQL_BLOB);
	my $nr = eval { $sth->execute };
	if (!defined($nr) \|\| $nr == 0) { # $nr may be `0E0'
	# delete from old, pre-SQL_BLOB rows:
	my $del_old = $self->{dbh}->prepare_cached(<<'');
	DELETE FROM blob2name WHERE fid = ? AND oidbin = ? AND name = ?

	$del_old->execute($fid, $oidbin, $$id); # missing-OK
	$del_old->execute($fid, $oidbin, $newbn); # ditto

	# may race with a clear_src, ensure new value exists
	$sth = $self->{dbh}->prepare_cached(<<'');
	INSERT OR IGNORE INTO blob2name (oidbin, fid, name) VALUES (?, ?, ?)

	$sth->bind_param(1, $oidbin, SQL_BLOB);
	$sth->bind_param(2, $fid);
	$sth->bind_param(3, $newbn, SQL_BLOB);
	$sth->execute;
	}
	$self->{dbh}->commit;
	}

	# read-only, iterates every oidbin + UID or name for a given folder
	sub each_src {
	my ($self, $folder, $cb, @args) = @_;
	my $dbh = $self->{dbh} //= dbh_new($self);
	my ($fid, @rng);
	my $and_ge_le = '';
	if (ref($folder) eq 'HASH') {
	$fid = $folder->{fid} // die "BUG: no `fid'";
	@rng = grep(defined, @$folder{qw(min max)});
	$and_ge_le = 'AND uid >= ? AND uid <= ?' if @rng;
	} else {
	$fid = $self->{fmap}->{$folder} //=
	fid_for($self, $folder) // return;
	}

	# minimize implicit txn time to avoid blocking writers by
	# batching SELECTs. This looks wonky but is necessary since
	# $cb-> may access the DB on its own.
	my $ary = $dbh->selectall_arrayref(<<"", undef, $fid, @rng);
	SELECT _rowid_,oidbin,uid FROM blob2num WHERE fid = ? $and_ge_le
	ORDER BY _rowid_ ASC LIMIT 1000

	my $min = @$ary ? $ary->[-1]->[0] : undef;
	while (defined $min) {
	for my $row (@$ary) { $cb->($row->[1], $row->[2], @args) }

	$ary = $dbh->selectall_arrayref(<<"", undef, $fid, @rng, $min);
	SELECT _rowid_,oidbin,uid FROM blob2num
	WHERE fid = ? $and_ge_le AND _rowid_ > ?
	ORDER BY _rowid_ ASC LIMIT 1000

	$min = @$ary ? $ary->[-1]->[0] : undef;
	}

	$ary = $dbh->selectall_arrayref(<<'', undef, $fid);
	SELECT _rowid_,oidbin,name FROM blob2name WHERE fid = ?
	ORDER BY _rowid_ ASC LIMIT 1000

	$min = @$ary ? $ary->[-1]->[0] : undef;
	while (defined $min) {
	for my $row (@$ary) { $cb->($row->[1], \($row->[2]), @args) }

	$ary = $dbh->selectall_arrayref(<<'', undef, $fid, $min);
	SELECT _rowid_,oidbin,name FROM blob2name WHERE fid = ? AND _rowid_ > ?
	ORDER BY _rowid_ ASC LIMIT 1000

	$min = @$ary ? $ary->[-1]->[0] : undef;
	}
	}

	sub location_stats {
	my ($self, $folder) = @_;
	my $dbh = $self->{dbh} //= dbh_new($self);
	my $fid;
	my $ret = {};
	$fid = $self->{fmap}->{$folder} //= fid_for($self, $folder) // return;
	my ($row) = $dbh->selectrow_array(<<"", undef, $fid);
	SELECT COUNT(name) FROM blob2name WHERE fid = ?

	$ret->{'name.count'} = $row if $row;
	my $ntype = ($folder =~ m!\A(?:nntps?\|s?news)://!i) ? 'article' :
	(($folder =~ m!\Aimaps?://!i) ? 'uid' : "TODO<$folder>");
	for my $op (qw(count min max)) {
	($row) = $dbh->selectrow_array(<<"", undef, $fid);
	SELECT $op(uid) FROM blob2num WHERE fid = ?

	$row or last;
	$ret->{"$ntype.$op"} = $row;
	}
	$ret;
	}

	# must be called with lock
	sub _forget_fids ($;@) {
	my $dbh = shift;
	$dbh->begin_work;
	for my $t (qw(blob2name blob2num folders)) {
	my $sth = $dbh->prepare_cached("DELETE FROM $t WHERE fid = ?");
	$sth->execute($_) for @_;
	}
	$dbh->commit;
	}

	# returns a { location => [ list-of-ids-or-names ] } mapping
	sub locations_for {
	my ($self, $oidbin) = @_;
	my ($fid, $sth, $id, %fid2id, %seen);
	my $dbh = $self->{dbh} //= dbh_new($self);
	$sth = $dbh->prepare('SELECT fid,uid FROM blob2num WHERE oidbin = ?');
	$sth->bind_param(1, $oidbin, SQL_BLOB);
	$sth->execute;
	while (my ($fid, $uid) = $sth->fetchrow_array) {
	push @{$fid2id{$fid}}, $uid;
	$seen{"$uid.$fid"} = 1;
	}

	# deal with 1.7.0 DBs :<
	$sth->bind_param(1, $oidbin, SQL_VARCHAR);
	$sth->execute;
	while (my ($fid, $uid) = $sth->fetchrow_array) {
	next if $seen{"$uid.$fid"};
	push @{$fid2id{$fid}}, $uid;
	}

	%seen = ();
	$sth = $dbh->prepare('SELECT fid,name FROM blob2name WHERE oidbin = ?');
	$sth->bind_param(1, $oidbin, SQL_BLOB);
	$sth->execute;
	while (my ($fid, $name) = $sth->fetchrow_array) {
	push @{$fid2id{$fid}}, $name;
	$seen{"$fid.$name"} = 1;
	}

	# deal with 1.7.0 DBs :<
	$sth->bind_param(1, $oidbin, SQL_VARCHAR);
	$sth->execute;
	while (my ($fid, $name) = $sth->fetchrow_array) {
	next if $seen{"$fid.$name"};
	push @{$fid2id{$fid}}, $name;
	}

	$sth = $dbh->prepare('SELECT loc FROM folders WHERE fid = ? LIMIT 1');
	my $ret = {};
	my $drop_fids = $dbh->{ReadOnly} ? undef : {};
	while (my ($fid, $ids) = each %fid2id) {
	$sth->execute($fid);
	my ($loc) = $sth->fetchrow_array;
	unless (defined $loc) {
	my $del = '';
	if ($drop_fids) {
	$del = ' (deleting)';
	$drop_fids->{$fid} = $fid;
	}
	my $oidhex = unpack('H*', $oidbin);
	warn "E: fid=$fid for $oidhex stale/unknown:\n", map {
	'E: '.(ref() ? $$_ : "#$_")."$del\n";
	} @$ids;
	next;
	}
	$ret->{$loc} = $ids;
	}
	if ($drop_fids && scalar(values %$drop_fids)) {
	my $lk = $self->lock_for_scope;
	_forget_fids($self->{dbh}, values %$drop_fids);
	}
	scalar(keys %$ret) ? $ret : undef;
	}

	# returns a list of folders used for completion
	sub folders {
	my ($self, @pfx) = @_;
	my $sql = 'SELECT loc FROM folders';
	my $re;
	if (defined($pfx[0])) {
	$sql .= ' WHERE loc REGEXP ?'; # DBD::SQLite uses perlre
	if (ref($pfx[0])) { # assume qr// "Regexp"
	$re = $pfx[0];
	} else {
	$re = !!$pfx[1] ? '.*' : '';
	$re .= quotemeta($pfx[0]);
	$re .= '.*';
	}
	}
	my $sth = ($self->{dbh} //= dbh_new($self))->prepare($sql);
	$sth->bind_param(1, $re) if defined($re);
	$sth->execute;
	map { $_->[0] } @{$sth->fetchall_arrayref};
	}

	sub blob_mismatch ($$$) {
	my ($f, $oidhex, $rawref) = @_;
	my $sha = $HEXLEN2SHA{length($oidhex)};
	my $got = git_sha($sha, $rawref)->hexdigest;
	$got eq $oidhex ? undef : warn("$f changed $oidhex => $got\n");
	}

	sub local_blob {
	my ($self, $oidhex, $vrfy) = @_;
	my $dbh = $self->{dbh} //= dbh_new($self);
	my $oidbin = pack('H*', $oidhex);

	my $b2n = $dbh->prepare(<<'');
	SELECT f.loc,b.name FROM blob2name b
	LEFT JOIN folders f ON b.fid = f.fid
	WHERE b.oidbin = ?

	$b2n->bind_param(1, $oidbin, SQL_BLOB);
	$b2n->execute;
	while (my ($d, $n) = $b2n->fetchrow_array) {
	substr($d, 0, length('maildir:')) = '';
	# n.b. both mbsync and offlineimap use ":2," as a suffix
	# in "new/", despite (from what I understand of reading
	# <https://cr.yp.to/proto/maildir.html>), the ":2," only
	# applies to files in "cur/".
	my @try = $n =~ /:2,[a-zA-Z]+\z/ ? qw(cur new) : qw(new cur);
	for my $x (@try) {
	my $f = "$d/$x/$n";
	open my $fh, '<', $f or next;
	# some (buggy) Maildir writers are non-atomic:
	my $raw = read_all($fh, -s $fh // next);
	next if $vrfy && blob_mismatch $f, $oidhex, \$raw;
	return \$raw;
	}
	}

	# MH, except `uid' is not always unique (can be packed)
	$b2n = $dbh->prepare(<<'');
	SELECT f.loc,b.uid FROM blob2num b
	LEFT JOIN folders f ON b.fid = f.fid
	WHERE b.oidbin = ? AND f.loc REGEXP '^mh:/'

	$b2n->bind_param(1, $oidbin, SQL_BLOB);
	$b2n->execute;
	while (my ($f, $n) = $b2n->fetchrow_array) {
	$f =~ s/\Amh://s or die "BUG: not MH: $f";
	$f .= "/$n";
	open my $fh, '<', $f or next;
	my $raw = read_all($fh, -s $fh // next);
	next if blob_mismatch $f, $oidhex, \$raw;
	return \$raw;
	}
	undef;
	}

	sub match_imap_url {
	my ($self, $url, $all) = @_; # $all = [ $lms->folders ];
	$all //= [ $self->folders ];
	require PublicInbox::URIimap;
	my $want = PublicInbox::URIimap->new($url)->canonical;
	my ($s, $h, $mb) = ($want->scheme, $want->host, $want->mailbox);
	my @uri = map { PublicInbox::URIimap->new($_)->canonical }
	grep(m!\A\Q$s\E://.?\Q$h\E\b.?/\Q$mb\E\b!, @$all);
	my @match;
	for my $x (@uri) {
	next if $x->mailbox ne $want->mailbox;
	next if $x->host ne $want->host;
	next if $x->port != $want->port;
	my $x_uidval = $x->uidvalidity;
	next if ($want->uidvalidity // $x_uidval) != $x_uidval;

	# allow nothing in want to possibly match ";AUTH=ANONYMOUS"
	if (defined($x->auth) && !defined($want->auth) &&
	!defined($want->user)) {
	push @match, $x;
	# or maybe user was forgotten on CLI:
	} elsif (defined($x->user) && !defined($want->user)) {
	push @match, $x;
	} elsif (($x->user//"\0") eq ($want->user//"\0")) {
	push @match, $x;
	}
	}
	return @match if wantarray;
	scalar(@match) <= 1 ? $match[0] :
	"E: `$url' is ambiguous:\n\t".join("\n\t", @match)."\n";
	}

	sub match_nntp_url ($$$) {
	my ($self, $url, $all) = @_; # $all = [ $lms->folders ];
	$all //= [ $self->folders ];
	require PublicInbox::URInntps;
	my $want = PublicInbox::URInntps->new($url)->canonical;
	my ($s, $h, $p) = ($want->scheme, $want->host, $want->port);
	my $ng = $want->group; # force scalar (no article ranges)
	my @uri = map { PublicInbox::URInntps->new($_)->canonical }
	grep(m!\A\Q$s\E://.?\Q$h\E\b.?/\Q$ng\E\b!, @$all);
	my @match;
	for my $x (@uri) {
	next if $x->group ne $ng \|\| $x->host ne $h \|\| $x->port != $p;
	# maybe user was forgotten on CLI:
	if (defined($x->userinfo) && !defined($want->userinfo)) {
	push @match, $x;
	} elsif (($x->userinfo//"\0") eq ($want->userinfo//"\0")) {
	push @match, $x;
	}
	}
	return @match if wantarray;
	scalar(@match) <= 1 ? $match[0] :
	"E: `$url' is ambiguous:\n\t".join("\n\t", @match)."\n";
	}

	# returns undef on failure, number on success
	sub group2folders {
	my ($self, $lei, $all, $folders) = @_;
	return $lei->fail(<<EOM) if @$folders;
	--all= not compatible with @$folders on command-line
	EOM
	my %x = map { $_ => $_ } split(/,/, $all);
	my @ok = grep(defined, delete(@x{qw(local remote), ''}));
	push(@ok, '') if $all eq '';
	my @no = keys %x;
	if (@no) {
	@no = (join(',', @no));
	return $lei->fail(<<EOM);
	--all=@no not accepted (must be `local' and/or `remote')
	EOM
	}
	my @all = $self->folders;
	for my $ok (@ok) {
	if ($ok eq 'local') {
	push @$folders, grep(!m!\A[a-z0-9\+]+://!i, @all);
	} elsif ($ok eq 'remote') {
	push @$folders, grep(m!\A[a-z0-9\+]+://!i, @all);
	} elsif ($ok ne '') {
	return $lei->fail("--all=$all not understood");
	} else {
	push @$folders, @all;
	}
	}
	@$folders = uniqstr @$folders;
	scalar(@$folders) \|\| $lei->fail(<<EOM);
	no --mail-sync folders known to lei
	EOM
	}

	# map CLI args to folder table entries, returns undef on failure
	sub arg2folder {
	my ($self, $lei, $folders) = @_;
	my @all = $self->folders;
	my %all = map { $_ => 1 } @all;
	my @no;
	for (@$folders) {
	next if $all{$_}; # ok
	if (m!\A(maildir\|mh):(.+)!i) {
	my $type = lc $1;
	my $d = "$type:".$lei->abs_path($2);
	push(@no, $_) unless $all{$d};
	$_ = $d;
	} elsif (-d "$_/new" && -d "$_/cur") {
	my $d = 'maildir:'.$lei->abs_path($_);
	push(@no, $_) unless $all{$d};
	$_ = $d;
	} elsif (m!\Aimaps?://!i) {
	my $orig = $_;
	my $res = match_imap_url($self, $orig, \@all);
	if (ref $res) {
	$_ = $$res;
	$lei->qerr(<<EOM);
	# using `$res' instead of `$orig'
	EOM
	} else {
	warn($res, "\n") if defined $res;
	push @no, $orig;
	}
	} elsif (m!\A(?:nntps?\|s?news)://!i) {
	my $orig = $_;
	my $res = match_nntp_url($self, $orig, \@all);
	if (ref $res) {
	$_ = $$res;
	$lei->qerr(<<EOM);
	# using `$res' instead of `$orig'
	EOM
	} else {
	warn($res, "\n") if defined $res;
	push @no, $orig;
	}
	} else {
	push @no, $_;
	}
	}
	if (@no) {
	my $no = join("\n\t", @no);
	die <<EOF;
	No sync information for: $no
	Run `lei ls-mail-sync' to display valid choices
	EOF
	}
	}

	sub forget_folders {
	my ($self, @folders) = @_;
	my $lk = $self->lock_for_scope;
	_forget_fids($self->{dbh}, map {
	delete($self->{fmap}->{$_}) //
	fid_for($self, $_) // ();
	} @folders);
	}

	# only used for changing canonicalization errors
	sub rename_folder {
	my ($self, $old, $new) = @_;
	my $lk = $self->lock_for_scope;
	my $ofid = delete($self->{fmap}->{$old}) //
	fid_for($self, $old) // return;
	eval {
	$self->{dbh}->do(<<EOM, undef, $new, $ofid);
	UPDATE folders SET loc = ? WHERE fid = ?
	EOM
	};
	if ($@ =~ /\bunique\b/i) {
	my $nfid = $self->{fmap}->{$new} // fid_for($self, $new);
	for my $t (qw(blob2name blob2num)) {
	$self->{dbh}->do(<<EOM, undef, $nfid, $ofid);
	UPDATE OR REPLACE $t SET fid = ? WHERE fid = ?
	EOM
	}
	$self->{dbh}->do(<<EOM, undef, $ofid);
	DELETE FROM folders WHERE fid = ?
	EOM
	}
	}

	sub num_oidbin ($$$) {
	my ($self, $url, $uid) = @_; # $url MUST have UIDVALIDITY if IMAP
	my $fid = $self->{fmap}->{$url} //= fid_for($self, $url) // return ();
	my $sth = $self->{dbh}->prepare_cached(<<EOM, undef, 1);
	SELECT oidbin FROM blob2num WHERE fid = ? AND uid = ? ORDER BY _rowid_
	EOM
	$sth->execute($fid, $uid);
	# for public-inbox <= 1.7.0:
	uniqstr(map { $_->[0] } @{$sth->fetchall_arrayref});
	}

	sub name_oidbin ($$$) {
	my ($self, $mdir, $nm) = @_;
	my $fid = $self->{fmap}->{$mdir} //= fid_for($self, $mdir) // return;
	my $sth = $self->{dbh}->prepare_cached(<<EOM, undef, 1);
	SELECT oidbin FROM blob2name WHERE fid = ? AND name = ?
	EOM
	$sth->bind_param(1, $fid);
	$sth->bind_param(2, $nm, SQL_BLOB);
	$sth->execute;
	my @bin = map { $_->[0] } @{$sth->fetchall_arrayref};
	$sth->bind_param(1, $fid);
	$sth->bind_param(2, $nm, SQL_VARCHAR);
	$sth->execute;
	my @old = map { $_->[0] } @{$sth->fetchall_arrayref};
	uniqstr @bin, @old # for public-inbox <= 1.7.0
	}

	sub imap_oidhex {
	my ($self, $lei, $uid_uri) = @_;
	my $mailbox_uri = $uid_uri->clone;
	$mailbox_uri->uid(undef);
	my $folders = [ $$mailbox_uri ];
	eval { $self->arg2folder($lei, $folders) };
	$lei->qerr("# no sync information for $mailbox_uri") if $@;
	map { unpack('H*',$_) } num_oidbin($self, $folders->[0], $uid_uri->uid)
	}

	1;