--- /dev/null
+/* Test the getusershell, setusershell, endusershell functions.
+ Copyright (C) 2024 Free Software Foundation, Inc.
+
+ This file 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.
+
+ This file 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 <https://www.gnu.org/licenses/>. */
+
+/* Written by Collin Funk <collin.funk1@gmail.com>, 2024. */
+
+#include <config.h>
+
+#include <unistd.h>
+#include <string.h>
+#include <stdlib.h>
+#include <stdio.h>
+
+#include "macros.h"
+
+/* The shell names in the order they appear in '/etc/shells'. */
+static char **shells = NULL;
+static size_t shell_count = 0;
+
+/* Prepare the shells array. */
+static void
+first_pass (void)
+{
+ char *ptr;
+ size_t i = 0;
+
+ /* Avoid reallocation. */
+ shell_count = 16;
+ shells = malloc (shell_count * sizeof (char *));
+
+ for (; (ptr = getusershell ()); ++i)
+ {
+ /* Make sure comments are ignored. */
+ ASSERT (ptr[0] != '#');
+ if (i >= shell_count)
+ {
+ shell_count *= 2;
+ shells = realloc (shells, shell_count * sizeof (char *));
+ ASSERT (shells != NULL);
+ }
+ shells[i] = strdup (ptr);
+ ASSERT (shells[i] != NULL);
+ }
+
+ shell_count = i;
+}
+
+/* Assuming that '/etc/shells' does not change during the duration of this
+ test, check that setusershell puts us back at the start of the file. */
+static void
+second_pass (void)
+{
+ size_t i;
+ char *ptr;
+
+ /* Return to the start of the file. */
+ setusershell ();
+
+ /* Make sure order is preserved. */
+ for (i = 0; i < shell_count; ++i)
+ {
+ ptr = getusershell ();
+ ASSERT (ptr != NULL);
+ ASSERT (STREQ (ptr, shells[i]));
+ printf ("%s\n", ptr);
+ free (shells[i]);
+ }
+
+ /* End of file. */
+ ASSERT (getusershell () == NULL);
+
+ /* Clean up. */
+ free (shells);
+ endusershell ();
+}
+
+int
+main (void)
+{
+ first_pass ();
+ second_pass ();
+
+ return 0;
+}