Add license headers and comments to source

Signed-off-by: David Oberhollenzer <david.oberhollenzer@tele2.at>

1 files changed, 46 insertions, 4 deletions

diff --git a/servicecmd/servicecmd.h b/servicecmd/servicecmd.h
index ce5e58f..27204d0 100644
--- a/servicecmd/servicecmd.h
+++ b/servicecmd/servicecmd.h
@@ -1,3 +1,20 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+/*
+ * Copyright (C) 2018 - David Oberhollenzer
+ *
+ * This program 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 program 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/>.
+ */
 #ifndef SERVICECMD_H
 #define SERVICECMD_H
 
@@ -8,21 +25,46 @@
 
 #include "util.h"
 
+/*
+	Describes a command that can be launched by passing its name as
+	second command line argument to the main() function (i.e. immediately
+	after the actual program name).
+
+	Short and long descriptions can be provided to print out help text.
+
+	The main() function calls into a callback in this structure to execute
+	the command.
+*/
 typedef struct command_t {
 	struct command_t *next;
 
-	const char *cmd;
-	const char *usage;
-	const char *s_desc;
-	const char *l_desc;
+	const char *cmd;	/* command name */
+	const char *usage;	/* list of possible arguments */
+	const char *s_desc;	/* short description used by help */
+	const char *l_desc;	/* long description used by help */
 
+	/*
+		Semantics are the same as for main(). Called from main()
+		function with first argument (i.e. top level program name)
+		removed.
+	*/
 	int (*run_cmd)(int argc, char **argv);
 } command_t;
 
+/* Global list of available commands */
 extern command_t *commands;
 
+/*
+	Implemented in servicecmd.c. Prints program usage message and
+	terminates with the given exit status.
+*/
 void usage(int status) NORETURN;
 
+/*
+	To implement a new command, add a global, static instance of a
+	command_t (or derived) structure to a C file and pass it to this
+	macro to have it automatically registered on program startup.
+*/
 #define REGISTER_COMMAND(cmd) \
 	static void __attribute__((constructor)) register_##cmd(void) \
 	{ \