zdump/opts: Make parsing of command line arguments testable

Make the C module responsible for the parsing of command-line arguments
independent of other global variables. This improves its testability.

Signed-off-by: Alexander Egorenkov <egorenar@linux.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>

zdump/opts.h

@@ -0,0 +1,38 @@
+/*
+ * Copyright IBM Corp. 2001, 2018
+ *
+ * s390-tools is free software; you can redistribute it and/or modify
+ * it under the terms of the MIT license. See LICENSE for details.
+ */
+
+#ifndef OPTS_H
+#define OPTS_H
+
+#include "zg.h"
+
+/*
+ * zgetdump options
+ */
+struct options {
+	const char 	*prog_name;
+	int		action_specified;
+	enum zg_action	action;
+	char		*device;
+	char		*mount_point;
+	int		fmt_specified;
+	const char	*fmt;
+	int		debug_specified;
+	char		**argv_fuse;
+	int		argc_fuse;
+	const char	*select;
+	int		select_specified;
+	int		verbose;
+};
+
+extern const char *OPTS_SELECT_KDUMP;
+extern const char *OPTS_SELECT_PROD;
+extern const char *OPTS_SELECT_ALL;
+
+void opts_parse(int argc, char *argv[], struct options *opts);
+
+#endif /* OPTS_H */