pam_motd: Fix segmentation fault when no motd_dir specified (#76)

This fixes a regression introduced by #69, where motd_path was set
to NULL and passed into strdup() if the motd_dir argument was
not specified in the configuration file. This caused a segmentation
fault.

* modules/pam_motd/pam_motd.c: fix checks for NULL in arguments
* xtests/Makefile.am: add test scripts and config file
* xtests/tst-pam_motd.sh: add running tst-pam_motd4.sh
* xtests/tst-pam_motd4.pamd: create
* xtests/tst-pam_motd4.sh: create

1 files changed, 27 insertions, 0 deletions

diff --git a/xtests/tst-pam_motd4.sh b/xtests/tst-pam_motd4.sh
new file mode 100755
index 00000000..6022177f
--- /dev/null
+++ b/xtests/tst-pam_motd4.sh
@@ -0,0 +1,27 @@
+#!/bin/bash
+
+TST_DIR="tst-pam_motd4.d"
+
+function tst_cleanup() {
+    rm -rf "${TST_DIR}"
+    rm -f tst-pam_motd4.out
+}
+
+mkdir -p ${TST_DIR}/etc
+
+# Verify the case of single motd with no motd_dir given in tst-pam_motd4.pamd
+echo "motd: /etc/motd" > ${TST_DIR}/etc/motd
+
+./tst-pam_motd tst-pam_motd4 > tst-pam_motd4.out
+
+RET=$?
+
+motd_to_show_output=$(cat tst-pam_motd4.out | grep "motd: /etc/motd")
+if [ -z "${motd_to_show_output}" ];
+then
+    tst_cleanup
+    exit 1
+fi
+
+tst_cleanup
+exit $RET