Fix the use of --checkpoint without explicit --checkpoint-action

* src/checkpoint.c (checkpoint_finish_compile): Set default action,
if necessary.
* tests/checkpoint/defaults.at: New testcase.
* tests/checkpoint/dot-compat.at: New testcase.
* tests/checkpoint/dot-int.at: New testcase.
* tests/checkpoint/dot.at: New testcase.
* tests/checkpoint/interval.at: New testcase.
* tests/Makefile.am: Add new testcases.
* tests/testsuite.at Include new testcases.

tests/checkpoint/defaults.at

@@ -0,0 +1,25 @@
+# This file is part of GNU tar test suite. -*- Autotest -*-
+# Copyright 2019 Free Software Foundation, Inc.
+#
+# GNU tar 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.
+#
+# GNU tar 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 this program.  If not, see <http://www.gnu.org/licenses/>.
+AT_SETUP([checkpoint defaults])
+AT_KEYWORDS([checkpoint checkpoint/defaults])
+CPT_CHECK([
+tar --checkpoint -c -f ../a.tar .
+],
+[0],
+[],
+[tar: Write checkpoint 10
+])
+AT_CLEANUP

tests/checkpoint/dot-compat.at

@@ -0,0 +1,23 @@
+# This file is part of GNU tar test suite. -*- Autotest -*-
+# Copyright 2019 Free Software Foundation, Inc.
+#
+# GNU tar 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.
+#
+# GNU tar 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 this program.  If not, see <http://www.gnu.org/licenses/>.
+AT_SETUP([dot action (compatibility syntax)])
+AT_KEYWORDS([checkpoint checkpoint/dot-compat])
+CPT_CHECK([
+tar --checkpoint=.2 -c -f ../a.tar .
+],
+[],
+[.....])
+AT_CLEANUP

tests/checkpoint/dot-int.at

@@ -0,0 +1,24 @@
+# This file is part of GNU tar test suite. -*- Autotest -*-
+# Copyright 2019 Free Software Foundation, Inc.
+#
+# GNU tar 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.
+#
+# GNU tar 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 this program.  If not, see <http://www.gnu.org/licenses/>.
+AT_SETUP([dot action and interval])
+AT_KEYWORDS([checkpoint checkpoint/dot-int])
+CPT_CHECK([
+tar --checkpoint-action=dot --checkpoint=2 -c -f ../a.tar .
+],
+[],
+[.....])
+AT_CLEANUP
+

tests/checkpoint/dot.at

@@ -0,0 +1,24 @@
+# This file is part of GNU tar test suite. -*- Autotest -*-
+# Copyright 2019 Free Software Foundation, Inc.
+#
+# GNU tar 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.
+#
+# GNU tar 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 this program.  If not, see <http://www.gnu.org/licenses/>.
+AT_SETUP([dot action])
+AT_KEYWORDS([checkpoint checkpoint/dot])
+CPT_CHECK([
+tar --checkpoint-action=dot -c -f ../a.tar .
+],
+[],
+[.])
+AT_CLEANUP
+

tests/checkpoint/interval.at

@@ -0,0 +1,29 @@
+# This file is part of GNU tar test suite. -*- Autotest -*-
+# Copyright 2019 Free Software Foundation, Inc.
+#
+# GNU tar 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.
+#
+# GNU tar 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 this program.  If not, see <http://www.gnu.org/licenses/>.
+AT_SETUP([checkpoint interval])
+AT_KEYWORDS([checkpoint checkpoint/interval])
+CPT_CHECK([
+tar --checkpoint=2 -c -f ../a.tar .
+],
+[0],
+[],
+[tar: Write checkpoint 2
+tar: Write checkpoint 4
+tar: Write checkpoint 6
+tar: Write checkpoint 8
+tar: Write checkpoint 10
+])
+AT_CLEANUP