Added basic infrastructure for manipulating settings.

src/core/settings.c

@@ -0,0 +1,148 @@
+/*
+ * Copyright (C) 2006 Michael Brown <mbrown@fensystems.co.uk>.
+ *
+ * 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 2 of the
+ * License, or 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, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <assert.h>
+#include <gpxe/settings.h>
+
+/** @file
+ *
+ * Configuration settings
+ *
+ */
+
+/** Registered configuration setting types */
+static struct config_setting_type
+config_setting_types[0] __table_start ( config_setting_types );
+static struct config_setting_type
+config_setting_types_end[0] __table_end ( config_setting_types );
+
+/** Registered configuration settings */
+static struct config_setting
+config_settings[0] __table_start ( config_settings );
+static struct config_setting
+config_settings_end[0] __table_end ( config_settings );
+
+/**
+ * Find configuration setting type
+ *
+ * @v name		Name
+ * @ret type		Configuration setting type, or NULL
+ */
+static struct config_setting_type *
+find_config_setting_type ( const char *name ) {
+	struct config_setting_type *type;
+
+	for ( type = config_setting_types ; type < config_setting_types_end ;
+	      type++ ) {
+		if ( strcmp ( name, type->name ) == 0 )
+			return type;
+	}
+	return NULL;
+}
+
+/**
+ * Find configuration setting
+ *
+ * @v name		Name
+ * @ret setting		Configuration setting, or NULL
+ */
+static struct config_setting * find_config_setting ( const char *name ) {
+	struct config_setting *setting;
+
+	for ( setting = config_settings ; setting < config_settings_end ;
+	      setting++ ) {
+		if ( strcmp ( name, setting->name ) == 0 )
+			return setting;
+	}
+	return NULL;
+}
+
+/**
+ * Find or build configuration setting
+ *
+ * @v name		Name
+ * @v tmp_setting	Temporary buffer for constructing a setting
+ * @ret setting		Configuration setting, or NULL
+ *
+ * Find setting if it exists.  If it doesn't exist, but the name is of
+ * the form "<num>.<type>" (e.g. "12.string"), then construct a
+ * setting for that tag and data type, and return it.  The constructed
+ * setting will be placed in the temporary buffer.
+ */
+static struct config_setting *
+find_or_build_config_setting ( const char *name,
+			       struct config_setting *tmp_setting ) {
+	struct config_setting *setting;
+	char *separator;
+
+	/* Look in the list of registered settings first */
+	setting = find_config_setting ( name );
+	if ( setting )
+		return setting;
+
+	/* If name is of the form "<num>.<type>", try to construct a setting */
+	setting = tmp_setting;
+	memset ( setting, 0, sizeof ( *setting ) );
+	setting->name = name;
+	setting->tag = strtoul ( name, &separator, 10 );
+	if ( *separator != '.' )
+		return NULL;
+	setting->type = find_config_setting_type ( separator + 1 );
+	if ( ! setting->type )
+		return NULL;
+	return setting;
+}
+
+/** Show value of setting
+ *
+ * @v context		Configuration context
+ * @v name		Configuration setting name
+ * @ret value		Setting value (as a string), or NULL
+ */
+const char * ( show_setting ) ( struct config_context *context,
+				const char *name ) {
+	struct config_setting *setting;
+	struct config_setting tmp_setting;
+
+	setting = find_or_build_config_setting ( name, &tmp_setting );
+	if ( ! setting )
+		return NULL;
+	return setting->type->show ( context, setting );
+}
+
+/** Set value of setting
+ *
+ * @v context		Configuration context
+ * @v name		Configuration setting name
+ * @v value		Setting value (as a string)
+ * @ret rc		Return status code
+ */
+int ( set_setting ) ( struct config_context *context, const char *name,
+		      const char *value ) {
+	struct config_setting *setting;
+	struct config_setting tmp_setting;
+
+	setting = find_or_build_config_setting ( name, &tmp_setting );
+	if ( ! setting )
+		return -ENOENT;
+	return setting->type->set ( context, setting, value );
+}

src/include/gpxe/settings.h

@@ -0,0 +1,103 @@
+#ifndef _GPXE_SETTINGS_H
+#define _GPXE_SETTINGS_H
+
+/** @file
+ *
+ * Configuration settings
+ *
+ */
+
+#include <stdint.h>
+#include <gpxe/dhcp.h>
+#include <gpxe/tables.h>
+
+struct config_setting;
+
+/**
+ * A configuration context
+ *
+ * This identifies the context within which settings are inspected and
+ * changed.  For example, the context might be global, or might be
+ * restricted to the settings stored in NVS on a particular device.
+ */
+struct config_context {
+	/** DHCP options block, or NULL
+	 *
+	 * If NULL, all registered DHCP options blocks will be used.
+	 */
+	struct dhcp_option_block *options;
+};
+
+/**
+ * A configuration setting type
+ *
+ * This represents a type of configuration setting (e.g. string, IPv4
+ * address, etc.).
+ */
+struct config_setting_type {
+	/** Name
+	 *
+	 * This is the name exposed to the user (e.g. "string").
+	 */
+	const char *name;
+	/** Show value of setting
+	 *
+	 * @v context		Configuration context
+	 * @v setting		Configuration setting
+	 * @ret value		Setting value (as a string), or NULL
+	 */
+	const char * ( * show ) ( struct config_context *context,
+				  struct config_setting *setting );
+	/** Set value of setting
+	 *
+	 * @v context		Configuration context
+	 * @v setting		Configuration setting
+	 * @v value		Setting value (as a string)
+	 * @ret rc		Return status code
+	 */ 
+	int ( * set ) ( struct config_context *context,
+			struct config_setting *setting,
+			const char *value );
+};
+
+/** Declare a configuration setting type */
+#define	__config_setting_type __table ( config_setting_types, 01 )
+
+/**
+ * A configuration setting
+ *
+ * This represents a single configuration setting (e.g. "hostname").
+ */
+struct config_setting {
+	/** Name
+	 *
+	 * This is the human-readable name for the setting.  Where
+	 * possible, it should match the name used in dhcpd.conf (see
+	 * dhcp-options(5)).
+	 */
+	const char *name;
+	/** DHCP option tag
+	 *
+	 * This is the DHCP tag used to identify the option in DHCP
+	 * packets and stored option blocks.
+	 */
+	unsigned int tag;
+	/** Configuration setting type
+	 *
+	 * This identifies the type of setting (e.g. string, IPv4
+	 * address, etc.).
+	 */
+	struct config_setting_type *type;
+};
+
+/** Declare a configuration setting */
+#define	__config_setting __table ( config_settings, 01 )
+
+/* Function prototypes */
+
+extern const char * ( show_setting ) ( struct config_context *context,
+				       const char *name );
+extern int ( set_setting ) ( struct config_context *context, const char *name,
+			     const char *value );
+
+#endif /* _GPXE_SETTINGS_H */