[settings] Allow for arbitrarily-named settings

This provides a mechanism for using arbitrarily-named variables within
gPXE, using the existing syntax for settings.

src/core/settings.c

@@ -41,65 +41,194 @@ FILE_LICENCE ( GPL2_OR_LATER );
 
 /******************************************************************************
  *
- * Registered settings blocks
+ * Generic settings blocks
  *
  ******************************************************************************
  */
 
 /**
- * Store value of simple setting
+ * A generic setting
  *
- * @v options		DHCP option block
+ */
+struct generic_setting {
+	/** List of generic settings */
+	struct list_head list;
+	/** Setting */
+	struct setting setting;
+	/** Size of setting name */
+	size_t name_len;
+	/** Size of setting data */
+	size_t data_len;
+};
+
+/**
+ * Get generic setting name
+ *
+ * @v generic		Generic setting
+ * @ret name		Generic setting name
+ */
+static inline void * generic_setting_name ( struct generic_setting *generic ) {
+	return ( ( ( void * ) generic ) + sizeof ( *generic ) );
+}
+
+/**
+ * Get generic setting data
+ *
+ * @v generic		Generic setting
+ * @ret data		Generic setting data
+ */
+static inline void * generic_setting_data ( struct generic_setting *generic ) {
+	return ( ( ( void * ) generic ) + sizeof ( *generic ) +
+		 generic->name_len );
+}
+
+/**
+ * Find generic setting
+ *
+ * @v generics		Generic settings block
+ * @v setting		Setting to find
+ * @ret generic		Generic setting, or NULL
+ */
+static struct generic_setting *
+find_generic_setting ( struct generic_settings *generics,
+		       struct setting *setting ) {
+	struct generic_setting *generic;
+
+	list_for_each_entry ( generic, &generics->list, list ) {
+		if ( setting_cmp ( &generic->setting, setting ) == 0 )
+			return generic;
+	}
+	return NULL;
+}
+
+/**
+ * Store value of generic setting
+ *
+ * @v settings		Settings block
  * @v setting		Setting to store
  * @v data		Setting data, or NULL to clear setting
  * @v len		Length of setting data
  * @ret rc		Return status code
  */
-int simple_settings_store ( struct settings *settings, struct setting *setting,
-			    const void *data, size_t len ) {
-	struct simple_settings *simple =
-		container_of ( settings, struct simple_settings, settings );
-	return dhcpopt_extensible_store ( &simple->dhcpopts, setting->tag,
-					  data, len );
+int generic_settings_store ( struct settings *settings,
+			     struct setting *setting,
+			     const void *data, size_t len ) {
+	struct generic_settings *generics =
+		container_of ( settings, struct generic_settings, settings );
+	struct generic_setting *old;
+	struct generic_setting *new = NULL;
+	size_t name_len;
+
+	/* Identify existing generic setting, if any */
+	old = find_generic_setting ( generics, setting );
+
+	/* Create new generic setting, if required */
+	if ( len ) {
+		/* Allocate new generic setting */
+		name_len = ( strlen ( setting->name ) + 1 );
+		new = zalloc ( sizeof ( *new ) + name_len + len );
+		if ( ! new )
+			return -ENOMEM;
+
+		/* Populate new generic setting */
+		new->name_len = name_len;
+		new->data_len = len;
+		memcpy ( &new->setting, setting, sizeof ( new->setting ) );
+		new->setting.name = generic_setting_name ( new );
+		memcpy ( generic_setting_name ( new ),
+			 setting->name, name_len );
+		memcpy ( generic_setting_data ( new ), data, len );
+	}
+
+	/* Delete existing generic setting, if any */
+	if ( old ) {
+		list_del ( &old->list );
+		free ( old );
+	}
+
+	/* Add new setting to list, if any */
+	if ( new )
+		list_add ( &new->list, &generics->list );
+
+	return 0;
 }
 
 /**
- * Fetch value of simple setting
+ * Fetch value of generic setting
  *
- * @v options		DHCP option block
+ * @v settings		Settings block
  * @v setting		Setting to fetch
  * @v data		Buffer to fill with setting data
  * @v len		Length of buffer
  * @ret len		Length of setting data, or negative error
  */
-int simple_settings_fetch ( struct settings *settings, struct setting *setting,
-			    void *data, size_t len ) {
-	struct simple_settings *simple =
-		container_of ( settings, struct simple_settings, settings );
-	return dhcpopt_fetch ( &simple->dhcpopts, setting->tag, data, len );
+int generic_settings_fetch ( struct settings *settings,
+			     struct setting *setting,
+			     void *data, size_t len ) {
+	struct generic_settings *generics =
+		container_of ( settings, struct generic_settings, settings );
+	struct generic_setting *generic;
+
+	/* Find generic setting */
+	generic = find_generic_setting ( generics, setting );
+	if ( ! generic )
+		return -ENOENT;
+
+	/* Copy out generic setting data */
+	if ( len > generic->data_len )
+		len = generic->data_len;
+	memcpy ( data, generic_setting_data ( generic ), len );
+	return generic->data_len;
 }
 
-/** Simple settings operations */
-struct settings_operations simple_settings_operations = {
-	.store = simple_settings_store,
-	.fetch = simple_settings_fetch,
+/**
+ * Clear generic settings block
+ *
+ * @v settings		Settings block
+ */
+void generic_settings_clear ( struct settings *settings ) {
+	struct generic_settings *generics =
+		container_of ( settings, struct generic_settings, settings );
+	struct generic_setting *generic;
+	struct generic_setting *tmp;
+
+	list_for_each_entry_safe ( generic, tmp, &generics->list, list ) {
+		list_del ( &generic->list );
+		free ( generic );
+	}
+	assert ( list_empty ( &generics->list ) );
+}
+
+/** Generic settings operations */
+struct settings_operations generic_settings_operations = {
+	.store = generic_settings_store,
+	.fetch = generic_settings_fetch,
+	.clear = generic_settings_clear,
 };
 
-/** Root simple settings block */
-struct simple_settings simple_settings_root = {
+/******************************************************************************
+ *
+ * Registered settings blocks
+ *
+ ******************************************************************************
+ */
+
+/** Root generic settings block */
+struct generic_settings generic_settings_root = {
 	.settings = {
 		.refcnt = NULL,
 		.name = "",
 		.siblings =
-		     LIST_HEAD_INIT ( simple_settings_root.settings.siblings ),
+		    LIST_HEAD_INIT ( generic_settings_root.settings.siblings ),
 		.children =
-		     LIST_HEAD_INIT ( simple_settings_root.settings.children ),
-		.op = &simple_settings_operations,
+		    LIST_HEAD_INIT ( generic_settings_root.settings.children ),
+		.op = &generic_settings_operations,
 	},
+	.list = LIST_HEAD_INIT ( generic_settings_root.list ),
 };
 
 /** Root settings block */
-#define settings_root simple_settings_root.settings
+#define settings_root generic_settings_root.settings
 
 /**
  * Find child named settings block
@@ -135,7 +264,7 @@ static struct settings * find_child_settings ( struct settings *parent,
 static struct settings * autovivify_child_settings ( struct settings *parent,
 						     const char *name ) {
 	struct {
-		struct simple_settings simple;
+		struct generic_settings generic;
 		char name[ strlen ( name ) + 1 /* NUL */ ];
 	} *new_child;
 	struct settings *settings;
@@ -144,7 +273,7 @@ static struct settings * autovivify_child_settings ( struct settings *parent,
 	if ( ( settings = find_child_settings ( parent, name ) ) != NULL )
 		return settings;
 
-	/* Create new simple settings block */
+	/* Create new generic settings block */
 	new_child = zalloc ( sizeof ( *new_child ) );
 	if ( ! new_child ) {
 		DBGC ( parent, "Settings %p could not create child %s\n",
@@ -152,12 +281,31 @@ static struct settings * autovivify_child_settings ( struct settings *parent,
 		return NULL;
 	}
 	memcpy ( new_child->name, name, sizeof ( new_child->name ) );
-	simple_settings_init ( &new_child->simple, NULL, new_child->name );
-	settings = &new_child->simple.settings;
+	generic_settings_init ( &new_child->generic, NULL, new_child->name );
+	settings = &new_child->generic.settings;
 	register_settings ( settings, parent );
 	return settings;
 }
 
+/**
+ * Return settings block name (for debug only)
+ *
+ * @v settings		Settings block
+ * @ret name		Settings block name
+ */
+static const char * settings_name ( struct settings *settings ) {
+	static char buf[64];
+	char tmp[ sizeof ( buf ) ];
+	int count;
+
+	for ( count = 0 ; settings ; settings = settings->parent ) {
+		memcpy ( tmp, buf, sizeof ( tmp ) );
+		snprintf ( buf, sizeof ( buf ), "%s%c%s", settings->name,
+			   ( count++ ? '.' : '\0' ), tmp );
+	}
+	return ( buf + 1 );
+}
+
 /**
  * Parse settings block name
  *
@@ -284,7 +432,8 @@ int register_settings ( struct settings *settings, struct settings *parent ) {
 	ref_get ( parent->refcnt );
 	settings->parent = parent;
 	list_add_tail ( &settings->siblings, &parent->children );
-	DBGC ( settings, "Settings %p registered\n", settings );
+	DBGC ( settings, "Settings %p (\"%s\") registered\n",
+	       settings, settings_name ( settings ) );
 
 	/* Fix up settings priority */
 	reprioritise_settings ( settings );
@@ -302,12 +451,14 @@ int register_settings ( struct settings *settings, struct settings *parent ) {
  */
 void unregister_settings ( struct settings *settings ) {
 
+	DBGC ( settings, "Settings %p (\"%s\") unregistered\n",
+	       settings, settings_name ( settings ) );
+
 	/* Remove from list of settings */
 	ref_put ( settings->refcnt );
 	ref_put ( settings->parent->refcnt );
 	settings->parent = NULL;
 	list_del ( &settings->siblings );
-	DBGC ( settings, "Settings %p unregistered\n", settings );
 
 	/* Apply potentially-updated settings */
 	apply_settings();
@@ -337,6 +488,10 @@ int store_setting ( struct settings *settings, struct setting *setting,
 	if ( ! settings )
 		settings = &settings_root;
 
+	/* Sanity check */
+	if ( ! settings->op->store )
+		return -ENOTSUP;
+
 	/* Store setting */
 	if ( ( rc = settings->op->store ( settings, setting,
 					  data, len ) ) != 0 )
@@ -384,6 +539,10 @@ int fetch_setting ( struct settings *settings, struct setting *setting,
 	if ( ! settings )
 		settings = &settings_root;
 
+	/* Sanity check */
+	if ( ! settings->op->fetch )
+		return -ENOTSUP;
+
 	/* Try this block first */
 	if ( ( ret = settings->op->fetch ( settings, setting,
 					   data, len ) ) >= 0 )
@@ -599,6 +758,16 @@ int fetch_uuid_setting ( struct settings *settings, struct setting *setting,
 	return len;
 }
 
+/**
+ * Clear settings block
+ *
+ * @v settings		Settings block
+ */
+void clear_settings ( struct settings *settings ) {
+	if ( settings->op->clear )
+		settings->op->clear ( settings );
+}
+
 /**
  * Compare two settings
  *
@@ -662,6 +831,26 @@ static struct setting * find_setting ( const char *name ) {
 	return NULL;
 }
 
+/**
+ * Parse setting name as tag number
+ *
+ * @v name		Name
+ * @ret tag		Tag number, or 0 if not a valid number
+ */
+static unsigned int parse_setting_tag ( const char *name ) {
+	char *tmp = ( ( char * ) name );
+	unsigned int tag = 0;
+
+	while ( 1 ) {
+		tag = ( ( tag << 8 ) | strtoul ( tmp, &tmp, 0 ) );
+		if ( *tmp == 0 )
+			return tag;
+		if ( *tmp != '.' )
+			return 0;
+		tmp++;
+	}
+}
+
 /**
  * Find setting type
  *
@@ -685,31 +874,35 @@ static struct setting_type * find_setting_type ( const char *name ) {
  * @v get_child		Function to find or create child settings block
  * @v settings		Settings block to fill in
  * @v setting		Setting to fill in
+ * @v tmp_name		Buffer for copy of setting name
  * @ret rc		Return status code
  *
  * Interprets a name of the form
  * "[settings_name/]tag_name[:type_name]" and fills in the appropriate
  * fields.
+ *
+ * The @c tmp_name buffer must be large enough to hold a copy of the
+ * setting name.
  */
 static int
 parse_setting_name ( const char *name,
 		     struct settings * ( * get_child ) ( struct settings *,
 							 const char * ),
-		     struct settings **settings, struct setting *setting ) {
-	char tmp_name[ strlen ( name ) + 1 ];
+		     struct settings **settings, struct setting *setting,
+		     char *tmp_name ) {
 	char *settings_name;
 	char *setting_name;
 	char *type_name;
 	struct setting *named_setting;
-	char *tmp;
 
 	/* Set defaults */
 	*settings = &settings_root;
 	memset ( setting, 0, sizeof ( *setting ) );
-	setting->type = &setting_type_hex;
+	setting->name = "";
+	setting->type = &setting_type_string;
 
 	/* Split name into "[settings_name/]setting_name[:type_name]" */
-	memcpy ( tmp_name, name, sizeof ( tmp_name ) );
+	strcpy ( tmp_name, name );
 	if ( ( setting_name = strchr ( tmp_name, '/' ) ) != NULL ) {
 		*(setting_name++) = 0;
 		settings_name = tmp_name;
@@ -730,25 +923,16 @@ parse_setting_name ( const char *name,
 		}
 	}
 
-	/* Identify tag number */
+	/* Identify setting */
 	if ( ( named_setting = find_setting ( setting_name ) ) != NULL ) {
+		/* Matches a defined named setting; use that setting */
 		memcpy ( setting, named_setting, sizeof ( *setting ) );
-	} else {
-		/* Unrecognised name: try to interpret as a tag number */
-		tmp = setting_name;
-		while ( 1 ) {
-			setting->tag = ( ( setting->tag << 8 ) |
-					 strtoul ( tmp, &tmp, 0 ) );
-			if ( *tmp == 0 )
-				break;
-			if ( *tmp != '.' ) {
-				DBG ( "Invalid setting \"%s\" in \"%s\"\n",
-				      setting_name, name );
-				return -ENOENT;
-			}
-			tmp++;
-		}
+	} else if ( ( setting->tag = parse_setting_tag ( setting_name ) ) !=0){
+		/* Is a valid numeric tag; use the tag */
 		setting->tag |= (*settings)->tag_magic;
+	} else {
+		/* Use the arbitrary name */
+		setting->name = setting_name;
 	}
 
 	/* Identify setting type, if specified */
@@ -774,10 +958,11 @@ parse_setting_name ( const char *name,
 int storef_named_setting ( const char *name, const char *value ) {
 	struct settings *settings;
 	struct setting setting;
+	char tmp_name[ strlen ( name ) + 1 ];
 	int rc;
 
 	if ( ( rc = parse_setting_name ( name, autovivify_child_settings,
-					 &settings, &setting ) ) != 0 )
+					 &settings, &setting, tmp_name )) != 0)
 		return rc;
 	return storef_setting ( settings, &setting, value );
 }
@@ -793,10 +978,11 @@ int storef_named_setting ( const char *name, const char *value ) {
 int fetchf_named_setting ( const char *name, char *buf, size_t len ) {
 	struct settings *settings;
 	struct setting setting;
+	char tmp_name[ strlen ( name ) + 1 ];
 	int rc;
 
 	if ( ( rc = parse_setting_name ( name, find_child_settings,
-					 &settings, &setting ) ) != 0 )
+					 &settings, &setting, tmp_name )) != 0)
 		return rc;
 	return fetchf_setting ( settings, &setting, buf, len );
 }