1 files changed, 93 insertions, 0 deletions
diff --git a/cmd/service/servicecmd.h b/cmd/service/servicecmd.h
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--- /dev/null
+++ b/cmd/service/servicecmd.h
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+/* 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
+
+#include <stdlib.h>
+#include <string.h>
+#include <stdio.h>
+#include <ctype.h>
+
+#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;	/* 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;
+
+/*
+	Write a message to stderr that advises the user how to consult the
+	help text for a specific command.
+*/
+void tell_read_help(const char *cmd);
+
+/*
+	Check if the argument count is within specified bounds (minc and maxc
+	inclusive). If it is, return 0.
+
+	If it isn't, complain about a wrong number of arguments for a
+	command (cmd), tell the user to consult the help text and return -1.
+*/
+int check_arguments(const char *cmd, int argc, int minc, int maxc);
+
+/*
+	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) \
+	{ \
+		command_t *c = (command_t *)&cmd; \
+		\
+		c->next = commands; \
+		commands = c; \
+	}
+
+#endif /* SERVICECMD_H */
+