conf: add configuration subsystem

The conf-subsystem is used throughout the whole source and provides a
global static read-only configuration. The configuration is read on
startup from the command-line and filesystem and then provided to the
other subsystems.

This is no database, that is, the data is not written to a file on
shutdown!

Signed-off-by: David Herrmann <dh.herrmann@googlemail.com>

src/conf.c

@@ -0,0 +1,119 @@
+/*
+ * App Configuration
+ *
+ * Copyright (c) 2012 David Herrmann <dh.herrmann@googlemail.com>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files
+ * (the "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included
+ * in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+ * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+ * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+ * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+ * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+ * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+/*
+ * Configuration
+ * Implementation of the configuration parsers.
+ */
+
+#include <errno.h>
+#include <getopt.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include "conf.h"
+#include "log.h"
+
+#define LOG_SUBSYSTEM "config"
+
+struct conf_obj conf_global = {
+	.exit = 0,
+	.debug = 0,
+	.verbose = 0,
+};
+
+static void print_help()
+{
+	fprintf(stderr,
+		"Usage:\n"
+		"\t%1$s [options]\n"
+		"\t%1$s [options] -h\n"
+		"General Options:\n"
+		"\t-h, --help                    Print this help and exit\n"
+		"\t-v, --verbose                 Print verbose messages\n"
+		"\t    --debug                   Enable debug mode\n",
+		"kmscon");
+}
+
+int conf_parse_argv(int argc, char **argv)
+{
+	int show_help = 0;
+	char short_options[] = ":hv";
+	struct option long_options[] = {
+		{ "help", no_argument, &show_help, 1 },
+		{ "verbose", no_argument, NULL, 'v' },
+		{ "debug", no_argument, &conf_global.debug, 1 },
+		{ NULL, 0, NULL, 0 },
+	};
+	int idx;
+	int c;
+
+	if (!argv || argc < 1)
+		return -EINVAL;
+
+	opterr = 0;
+	while (1) {
+		c = getopt_long(argc, argv, short_options,
+				long_options, &idx);
+		if (c < 0)
+			break;
+		switch (c) {
+		case 0:
+			break;
+		case 'h':
+			show_help = 1;
+			break;
+		case 'v':
+			conf_global.verbose = 1;
+			break;
+		case ':':
+			fprintf(stderr, "Missing argument for option -%c\n",
+				optopt);
+			break;
+		case '?':
+			if (optopt)
+				fprintf(stderr, "Unknown argument -%c\n",
+					optopt);
+			else
+				fprintf(stderr, "Unknown argument %s\n",
+					argv[optind - 1]);
+			break;
+		}
+	}
+
+	if (optind != argc)
+		fprintf(stderr, "Unparsed remaining arguments\n");
+
+	if (conf_global.debug)
+		conf_global.verbose = 1;
+
+	if (show_help) {
+		print_help();
+		conf_global.exit = 1;
+	}
+
+	return 0;
+}

src/conf.h

@@ -0,0 +1,58 @@
+/*
+ * App Configuration
+ *
+ * Copyright (c) 2012 David Herrmann <dh.herrmann@googlemail.com>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files
+ * (the "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included
+ * in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+ * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+ * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+ * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+ * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+ * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+/*
+ * Configuration
+ * This file provides a static global configuration. Several functions are
+ * available which parse external data like command-line options or
+ * configuration-files into the global configuration "conf_global".
+ * All subsystems can add their parsers and values here so the single
+ * configuration object will be sufficient to configure the whole application.
+ *
+ * The data is static and should be considered read-only. Only on startup the
+ * configuration is written, all later functions should only read it. This is no
+ * database so there is no reason to write the config again.
+ */
+
+#ifndef CONFIG_CONFIG_H
+#define CONFIG_CONFIG_H
+
+#include <stdlib.h>
+#include <unistd.h>
+
+struct conf_obj {
+	/* exit application after parsing options */
+	int exit;
+	/* enable debug messages */
+	int debug;
+	/* enable verbose info messages */
+	int verbose;
+};
+
+extern struct conf_obj conf_global;
+
+int conf_parse_argv(int argc, char **argv);
+
+#endif /* CONFIG_CONFIG_H */