[type/__debconf_set_selections] Add state explorer

…and to make it work, replace --file with --line.

--file is deprecated because it does not work with the state explorer as the
contents of the file are not available on the target.

cdist/conf/type/__debconf_set_selections/explorer/state

@@ -0,0 +1,124 @@
+#!/bin/sh -e
+#
+# 2021 Dennis Camera (dennis.camera at ssrq-sds-fds.ch)
+#
+# This file is part of cdist.
+#
+# cdist is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# cdist is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with cdist. If not, see <http://www.gnu.org/licenses/>.
+#
+# Determine current debconf selections' state.
+# Prints one of:
+#   present: all selections are already set as they should.
+#   different: one or more of the selections have a different value.
+#   absent: one or more of the selections are not (currently) defined.
+#
+
+test -x /usr/bin/perl || {
+	# cannot find perl (no perl ~ no debconf)
+	echo 'absent'
+	exit 0
+}
+
+linesfile="${__object:?}/parameter/line"
+test -s "${linesfile}" || {
+	if test -s "${__object:?}/parameter/file"
+	then
+		echo absent
+	else
+		echo present
+	fi
+	exit 0
+}
+
+/usr/bin/perl -- - "${linesfile}" <<'EOF'
+use strict;
+use warnings "all";
+
+use Debconf::Db;
+use Debconf::Question;
+
+# Extract @known... arrays from debconf-set-selections
+# These values are required to distinguish flags and values in the given lines.
+# DC: I couldn't think of a more ugly solution to the problem…
+my @knownflags;
+my @knowntypes;
+my $debconf_set_selections = '/usr/bin/debconf-set-selections';
+if (-e $debconf_set_selections) {
+	my $sed_known = 's/^my \(@known\(flags\|types\) = qw([a-z ]*);\).*$/\1/p';
+	eval `sed -n '$sed_known' '$debconf_set_selections'`;
+}
+
+sub mungeline ($) {
+	my $line = shift;
+	chomp $line;
+	$line =~ s/\r$//;
+	return $line;
+}
+
+sub fatal { printf STDERR @_; exit 1; }
+
+my $state = 'present';
+
+sub state {
+	my $new = shift;
+	if ($state eq 'present'
+	    or ($state eq 'different' and $new eq 'absent')) {
+		$state = $new;
+	}
+}
+
+Debconf::Db->load(readonly => 'true');
+
+while (<>) {
+	# Read and process lines (taken from debconf-set-selections)
+	$_ = mungeline($_);
+	while (/\\$/ && ! eof) {
+		s/\\$//;
+		$_ .= mungeline(<>);
+	}
+	next if /^\s*$/ || /^\s*\#/;
+
+	my ($owner, $label, $type, $content) = /^\s*(\S+)\s+(\S+)\s+(\S+)(?:\s(.*))?/
+		or fatal "invalid line: %s\n", $_;
+	$content = '' unless defined $content;
+
+
+	# Compare is and should state
+	my $q = Debconf::Question->get($label);
+
+	unless (defined $q) {
+		# probably a preseed
+		state 'absent';
+		next;
+	}
+
+	if (grep { $_ eq $q->type } @knownflags) {
+		# This line wants to set a flag, presumably.
+		if ($q->flag($q->type) ne $content) {
+			state 'different';
+		}
+	} else {
+		# Otherwise, it's probably a value…
+		if ($q->value ne $content) {
+			state 'different';
+		}
+
+		unless (grep { $_ eq $owner } (split /, /, $q->owners)) {
+			state 'different';
+		}
+	}
+}
+
+printf "%s\n", $state;
+EOF

cdist/conf/type/__debconf_set_selections/gencode-remote

@@ -1,6 +1,7 @@
 #!/bin/sh -e
 #
 # 2011-2014 Nico Schottelius (nico-cdist at schottelius.org)
+# 2021 Dennis Camera (dennis.camera at ssrq-sds-fds.ch)
 #
 # This file is part of cdist.
 #
@@ -17,16 +18,32 @@
 # You should have received a copy of the GNU General Public License
 # along with cdist. If not, see <http://www.gnu.org/licenses/>.
 #
-#
-# Setup selections
-#
 
-filename="$(cat "$__object/parameter/file")"
-
-if [ "$filename" = "-" ]; then
-    filename="$__object/stdin"
+if test -f "${__object:?}/parameter/line"
+then
+	filename="${__object:?}/parameter/line"
+elif test -s "${__object:?}/parameter/file"
+then
+	filename=$(cat "${__object:?}/parameter/file")
+	if test "${filename}" = '-'
+	then
+		filename="${__object:?}/stdin"
+	fi
+else
+	printf 'Neither --line nor --file set.\n' >&2
+	exit 1
 fi
 
-echo "debconf-set-selections << __file-eof"
-cat "$filename"
-echo "__file-eof"
+# setting no lines makes no sense
+test -s "${filename}" || exit 0
+
+state_is=$(cat "${__object:?}/explorer/state")
+
+if test "${state_is}" != 'present'
+then
+	cat <<-CODE
+	debconf-set-selections <<'EOF'
+	$(cat "${filename}")
+	EOF
+	CODE
+fi

cdist/conf/type/__debconf_set_selections/man.rst

@@ -8,15 +8,33 @@ cdist-type__debconf_set_selections - Setup debconf selections
 
 DESCRIPTION
 -----------
-On Debian and alike systems debconf-set-selections(1) can be used
+On Debian and alike systems :strong:`debconf-set-selections`\ (1) can be used
 to setup configuration parameters.
 
 
 REQUIRED PARAMETERS
 -------------------
+cf. ``--line``.
+
+
+OPTIONAL PARAMETERS
+-------------------
 file
-   Use the given filename as input for debconf-set-selections(1)
-   If filename is "-", read from stdin.
+   Use the given filename as input for :strong:`debconf-set-selections`\ (1)
+   If filename is ``-``, read from stdin.
+
+   **This parameter is deprecated, because it doesn't work with state detection.**
+line
+   A line in :strong:`debconf-set-selections`\ (1) compatible format.
+   This parameter can be used multiple times to set multiple options.
+
+   (This parameter is actually required, but marked optional because the
+   deprecated ``--file`` is still accepted.)
+
+
+BOOLEAN PARAMETERS
+------------------
+None.
 
 
 EXAMPLES
@@ -24,30 +42,29 @@ EXAMPLES
 
 .. code-block:: sh
 
-    # Setup configuration for nslcd
-    __debconf_set_selections nslcd --file /path/to/file
+    # Setup gitolite's gituser
+    __debconf_set_selections nslcd --line 'gitolite gitolite/gituser string git'
 
-    # Setup configuration for nslcd from another type
-    __debconf_set_selections nslcd --file "$__type/files/preseed/nslcd"
-
-    __debconf_set_selections nslcd --file - << eof
-    gitolite gitolite/gituser string git
-    eof
+    # Setup configuration for nslcd from a file.
+    # NB: Multiple lines can be passed to --line, although this can be considered a hack.
+    __debconf_set_selections nslcd --line "$(cat "${__files:?}/preseed/nslcd.debconf")"
 
 
 SEE ALSO
 --------
-:strong:`debconf-set-selections`\ (1), :strong:`cdist-type__update_alternatives`\ (7)
+- :strong:`cdist-type__update_alternatives`\ (7)
+- :strong:`debconf-set-selections`\ (1)
 
 
 AUTHORS
 -------
 Nico Schottelius <nico-cdist--@--schottelius.org>
+Dennis Camera <dennis.camera--@--ssrq-sds-fds.ch>
 
 
 COPYING
 -------
-Copyright \(C) 2011-2014 Nico Schottelius. You can redistribute it
-and/or modify it under the terms of the GNU General Public License as
-published by the Free Software Foundation, either version 3 of the
-License, or (at your option) any later version.
+Copyright \(C) 2011-2014 Nico Schottelius, 2021 Dennis Camera.
+You can redistribute it and/or modify it under the terms of the GNU General
+Public License as published by the Free Software Foundation, either version 3 of
+the License, or (at your option) any later version.

cdist/conf/type/__debconf_set_selections/manifest

@@ -0,0 +1,21 @@
+#!/bin/sh -e
+#
+# 2021 Dennis Camera (dennis.camera at ssrq-sds-fds.ch)
+#
+# This file is part of cdist.
+#
+# cdist is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# cdist is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with cdist. If not, see <http://www.gnu.org/licenses/>.
+#
+
+__package_apt debconf

cdist/conf/type/__debconf_set_selections/parameter/optional_multiple

@@ -0,0 +1 @@
+line