1 files changed, 74 insertions, 0 deletions
diff --git a/lib/shells.c b/lib/shells.c
new file mode 100644
index 0000000..6693ab0
--- /dev/null
+++ b/lib/shells.c
@@ -0,0 +1,74 @@
+/*
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+#include <sys/syslog.h>
+#if defined (HAVE_LIBECONF) && defined (USE_VENDORDIR)
+#include <libeconf.h>
+#endif
+
+#include "closestream.h"
+#include "shells.h"
+
+/*
+ *  is_known_shell() -- if the given shell appears in /etc/shells
+ *  or vendor defined files.
+ *  Return 1 if found and return 0 if not found.
+ */
+extern int is_known_shell(const char *shell_name)
+{
+	int ret = 0;
+
+#if defined (HAVE_LIBECONF) && defined (USE_VENDORDIR)
+	size_t size = 0;
+	econf_err error;
+	char **keys;
+	econf_file *key_file;
+
+	error = econf_readDirs(&key_file,
+			       _PATH_VENDORDIR,
+			       "/etc",
+			       "shells",
+			       NULL,
+			       "", /* key only */
+			       "#" /* comment */);
+	if (error) {
+		syslog(LOG_ALERT,
+		       _("Cannot parse shells files: %s"),
+		       econf_errString(error));
+		exit(EXIT_FAILURE);
+	}
+
+	error = econf_getKeys(key_file, NULL, &size, &keys);
+	if (error) {
+		syslog(LOG_ALERT,
+		       _("Cannot evaluate entries in shells files: %s"),
+		       econf_errString(error));
+		econf_free (key_file);
+		exit(EXIT_FAILURE);
+	}
+
+	for (size_t i = 0; i < size; i++) {
+		if (strcmp (keys[i], shell_name) == 0) {
+			ret = 1;
+			break;
+		}
+	}
+	econf_free (key_file);	
+#else
+	char *s;
+
+	if (!shell_name)
+		return 0;
+
+	setusershell();
+	while ((s = getusershell())) {
+		if (*s != '#' && strcmp(shell_name, s) == 0) {
+			ret = 1;
+			break;
+		}
+	}
+	endusershell();
+#endif
+	return ret;
+}
+