dtc: Add ability to delete nodes and properties

dtc currently allows the contents of properties to be changed, and the
contents of nodes to be added to. There are situations where removing
properties or nodes may be useful. This change implements the following
syntax to do that:

    / {
        /delete-property/ propname;
        /delete-node/ nodename;
    };

or:

    /delete-node/ &noderef;

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Acked-by: David Gibson <david@gibson.dropbear.id.au>

checks.c

@@ -256,12 +256,16 @@ static void check_duplicate_property_names(struct check *c, struct node *dt,
 {
 	struct property *prop, *prop2;
 
-	for_each_property(node, prop)
-		for (prop2 = prop->next; prop2; prop2 = prop2->next)
+	for_each_property(node, prop) {
+		for (prop2 = prop->next; prop2; prop2 = prop2->next) {
+			if (prop2->deleted)
+				continue;
 			if (streq(prop->name, prop2->name))
 				FAIL(c, "Duplicate property name %s in %s",
 				     prop->name, node->fullpath);
 		}
+	}
+}
 NODE_ERROR(duplicate_property_names, NULL);
 
 #define LOWERCASE	"abcdefghijklmnopqrstuvwxyz"

dtc-lexer.l

@@ -103,6 +103,20 @@ static int pop_input_file(void);
 			return DT_BITS;
 		}
 
+<*>"/delete-property/"	{
+			DPRINT("Keyword: /delete-property/\n");
+			DPRINT("<PROPNODENAME>\n");
+			BEGIN(PROPNODENAME);
+			return DT_DEL_PROP;
+		}
+
+<*>"/delete-node/"	{
+			DPRINT("Keyword: /delete-node/\n");
+			DPRINT("<PROPNODENAME>\n");
+			BEGIN(PROPNODENAME);
+			return DT_DEL_NODE;
+		}
+
 <*>{LABEL}:	{
 			DPRINT("Label: %s\n", yytext);
 			yylval.labelref = xstrdup(yytext);

dtc-parser.y

@@ -62,6 +62,8 @@ static unsigned char eval_char_literal(const char *s);
 %token DT_MEMRESERVE
 %token DT_LSHIFT DT_RSHIFT DT_LE DT_GE DT_EQ DT_NE DT_AND DT_OR
 %token DT_BITS
+%token DT_DEL_PROP
+%token DT_DEL_NODE
 %token <propnodename> DT_PROPNODENAME
 %token <literal> DT_LITERAL
 %token <literal> DT_CHAR_LITERAL
@@ -153,6 +155,17 @@ devicetree:
 				print_error("label or path, '%s', not found", $2);
 			$$ = $1;
 		}
+	| devicetree DT_DEL_NODE DT_REF ';'
+		{
+			struct node *target = get_node_by_ref($1, $3);
+
+			if (!target)
+				print_error("label or path, '%s', not found", $3);
+			else
+				delete_node(target);
+
+			$$ = $1;
+		}
 	;
 
 nodedef:
@@ -182,6 +195,10 @@ propdef:
 		{
 			$$ = build_property($1, empty_data);
 		}
+	| DT_DEL_PROP DT_PROPNODENAME ';'
+		{
+			$$ = build_property_delete($2);
+		}
 	| DT_LABEL propdef
 		{
 			add_label(&$2->labels, $1);
@@ -440,6 +457,10 @@ subnode:
 		{
 			$$ = name_node($2, $1);
 		}
+	| DT_DEL_NODE DT_PROPNODENAME ';'
+		{
+			$$ = name_node(build_node_delete(), $2);
+		}
 	| DT_LABEL subnode
 		{
 			add_label(&$2->labels, $1);

dtc.h

@@ -128,11 +128,13 @@ int data_is_one_string(struct data d);
 
 /* Live trees */
 struct label {
+	int deleted;
 	char *label;
 	struct label *next;
 };
 
 struct property {
+	int deleted;
 	char *name;
 	struct data val;
 
@@ -142,6 +144,7 @@ struct property {
 };
 
 struct node {
+	int deleted;
 	char *name;
 	struct property *proplist;
 	struct node *children;
@@ -158,28 +161,71 @@ struct node {
 	struct label *labels;
 };
 
+static inline struct label *for_each_label_next(struct label *l)
+{
+	do {
+		l = l->next;
+	} while (l && l->deleted);
+
+	return l;
+}
+
 #define for_each_label(l0, l) \
+	for ((l) = (l0); (l); (l) = for_each_label_next(l))
+
+#define for_each_label_withdel(l0, l) \
 	for ((l) = (l0); (l); (l) = (l)->next)
 
+static inline struct property *for_each_property_next(struct property *p)
+{
+	do {
+		p = p->next;
+	} while (p && p->deleted);
+
+	return p;
+}
+
 #define for_each_property(n, p) \
+	for ((p) = (n)->proplist; (p); (p) = for_each_property_next(p))
+
+#define for_each_property_withdel(n, p) \
 	for ((p) = (n)->proplist; (p); (p) = (p)->next)
 
+static inline struct node *for_each_child_next(struct node *c)
+{
+	do {
+		c = c->next_sibling;
+	} while (c && c->deleted);
+
+	return c;
+}
+
 #define for_each_child(n, c) \
+	for ((c) = (n)->children; (c); (c) = for_each_child_next(c))
+
+#define for_each_child_withdel(n, c) \
 	for ((c) = (n)->children; (c); (c) = (c)->next_sibling)
 
 void add_label(struct label **labels, char *label);
+void delete_labels(struct label **labels);
 
 struct property *build_property(char *name, struct data val);
+struct property *build_property_delete(char *name);
 struct property *chain_property(struct property *first, struct property *list);
 struct property *reverse_properties(struct property *first);
 
 struct node *build_node(struct property *proplist, struct node *children);
+struct node *build_node_delete(void);
 struct node *name_node(struct node *node, char *name);
 struct node *chain_node(struct node *first, struct node *list);
 struct node *merge_nodes(struct node *old_node, struct node *new_node);
 
 void add_property(struct node *node, struct property *prop);
+void delete_property_by_name(struct node *node, char *name);
+void delete_property(struct property *prop);
 void add_child(struct node *parent, struct node *child);
+void delete_node_by_name(struct node *parent, char *name);
+void delete_node(struct node *node);
 
 const char *get_unitname(struct node *node);
 struct property *get_property(struct node *node, const char *propname);

flattree.c

@@ -263,6 +263,9 @@ static void flatten_tree(struct node *tree, struct emitter *emit,
 	struct node *child;
 	int seen_name_prop = 0;
 
+	if (tree->deleted)
+		return;
+
 	emit->beginnode(etarget, tree->labels);
 
 	if (vi->flags & FTF_FULLPATH)

livetree.c

@@ -29,9 +29,11 @@ void add_label(struct label **labels, char *label)
 	struct label *new;
 
 	/* Make sure the label isn't already there */
-	for_each_label(*labels, new)
-		if (streq(new->label, label))
+	for_each_label_withdel(*labels, new)
+		if (streq(new->label, label)) {
+			new->deleted = 0;
 			return;
+		}
 
 	new = xmalloc(sizeof(*new));
 	new->label = label;
@@ -39,6 +41,14 @@ void add_label(struct label **labels, char *label)
 	*labels = new;
 }
 
+void delete_labels(struct label **labels)
+{
+	struct label *label;
+
+	for_each_label(*labels, label)
+		label->deleted = 1;
+}
+
 struct property *build_property(char *name, struct data val)
 {
 	struct property *new = xmalloc(sizeof(*new));
@@ -51,6 +61,18 @@ struct property *build_property(char *name, struct data val)
 	return new;
 }
 
+struct property *build_property_delete(char *name)
+{
+	struct property *new = xmalloc(sizeof(*new));
+
+	memset(new, 0, sizeof(*new));
+
+	new->name = name;
+	new->deleted = 1;
+
+	return new;
+}
+
 struct property *chain_property(struct property *first, struct property *list)
 {
 	assert(first->next == NULL);
@@ -91,6 +113,17 @@ struct node *build_node(struct property *proplist, struct node *children)
 	return new;
 }
 
+struct node *build_node_delete(void)
+{
+	struct node *new = xmalloc(sizeof(*new));
+
+	memset(new, 0, sizeof(*new));
+
+	new->deleted = 1;
+
+	return new;
+}
+
 struct node *name_node(struct node *node, char *name)
 {
 	assert(node->name == NULL);
@@ -106,8 +139,10 @@ struct node *merge_nodes(struct node *old_node, struct node *new_node)
 	struct node *new_child, *old_child;
 	struct label *l;
 
+	old_node->deleted = 0;
+
 	/* Add new node labels to old node */
-	for_each_label(new_node->labels, l)
+	for_each_label_withdel(new_node->labels, l)
 		add_label(&old_node->labels, l->label);
 
 	/* Move properties from the new node to the old node.  If there
@@ -118,14 +153,21 @@ struct node *merge_nodes(struct node *old_node, struct node *new_node)
 		new_node->proplist = new_prop->next;
 		new_prop->next = NULL;
 
+		if (new_prop->deleted) {
+			delete_property_by_name(old_node, new_prop->name);
+			free(new_prop);
+			continue;
+		}
+
 		/* Look for a collision, set new value if there is */
-		for_each_property(old_node, old_prop) {
+		for_each_property_withdel(old_node, old_prop) {
 			if (streq(old_prop->name, new_prop->name)) {
 				/* Add new labels to old property */
-				for_each_label(new_prop->labels, l)
+				for_each_label_withdel(new_prop->labels, l)
 					add_label(&old_prop->labels, l->label);
 
 				old_prop->val = new_prop->val;
+				old_prop->deleted = 0;
 				free(new_prop);
 				new_prop = NULL;
 				break;
@@ -146,8 +188,14 @@ struct node *merge_nodes(struct node *old_node, struct node *new_node)
 		new_child->parent = NULL;
 		new_child->next_sibling = NULL;
 
+		if (new_child->deleted) {
+			delete_node_by_name(old_node, new_child->name);
+			free(new_child);
+			continue;
+		}
+
 		/* Search for a collision.  Merge if there is */
-		for_each_child(old_node, old_child) {
+		for_each_child_withdel(old_node, old_child) {
 			if (streq(old_child->name, new_child->name)) {
 				merge_nodes(old_child, new_child);
 				new_child = NULL;
@@ -188,6 +236,25 @@ void add_property(struct node *node, struct property *prop)
 	*p = prop;
 }
 
+void delete_property_by_name(struct node *node, char *name)
+{
+	struct property *prop = node->proplist;
+
+	while (prop) {
+		if (!strcmp(prop->name, name)) {
+			delete_property(prop);
+			return;
+		}
+		prop = prop->next;
+	}
+}
+
+void delete_property(struct property *prop)
+{
+	prop->deleted = 1;
+	delete_labels(&prop->labels);
+}
+
 void add_child(struct node *parent, struct node *child)
 {
 	struct node **p;
@@ -202,6 +269,32 @@ void add_child(struct node *parent, struct node *child)
 	*p = child;
 }
 
+void delete_node_by_name(struct node *parent, char *name)
+{
+	struct node *node = parent->children;
+
+	while (node) {
+		if (!strcmp(node->name, name)) {
+			delete_node(node);
+			return;
+		}
+		node = node->next_sibling;
+	}
+}
+
+void delete_node(struct node *node)
+{
+	struct property *prop;
+	struct node *child;
+
+	node->deleted = 1;
+	for_each_child(node, child)
+		delete_node(child);
+	for_each_property(node, prop)
+		delete_property(prop);
+	delete_labels(&node->labels);
+}
+
 struct reserve_info *build_reserve_entry(uint64_t address, uint64_t size)
 {
 	struct reserve_info *new = xmalloc(sizeof(*new));
@@ -353,8 +446,11 @@ struct node *get_node_by_path(struct node *tree, const char *path)
 	const char *p;
 	struct node *child;
 
-	if (!path || ! (*path))
+	if (!path || ! (*path)) {
+		if (tree->deleted)
+			return NULL;
 		return tree;
+	}
 
 	while (path[0] == '/')
 		path++;
@@ -397,8 +493,11 @@ struct node *get_node_by_phandle(struct node *tree, cell_t phandle)
 
 	assert((phandle != 0) && (phandle != -1));
 
-	if (tree->phandle == phandle)
+	if (tree->phandle == phandle) {
+		if (tree->deleted)
+			return NULL;
 		return tree;
+	}
 
 	for_each_child(tree, child) {
 		node = get_node_by_phandle(child, phandle);
@@ -535,7 +634,7 @@ static void sort_properties(struct node *node)
 	int n = 0, i = 0;
 	struct property *prop, **tbl;
 
-	for_each_property(node, prop)
+	for_each_property_withdel(node, prop)
 		n++;
 
 	if (n == 0)
@@ -543,7 +642,7 @@ static void sort_properties(struct node *node)
 
 	tbl = xmalloc(n * sizeof(*tbl));
 
-	for_each_property(node, prop)
+	for_each_property_withdel(node, prop)
 		tbl[i++] = prop;
 
 	qsort(tbl, n, sizeof(*tbl), cmp_prop);
@@ -571,7 +670,7 @@ static void sort_subnodes(struct node *node)
 	int n = 0, i = 0;
 	struct node *subnode, **tbl;
 
-	for_each_child(node, subnode)
+	for_each_child_withdel(node, subnode)
 		n++;
 
 	if (n == 0)
@@ -579,7 +678,7 @@ static void sort_subnodes(struct node *node)
 
 	tbl = xmalloc(n * sizeof(*tbl));
 
-	for_each_child(node, subnode)
+	for_each_child_withdel(node, subnode)
 		tbl[i++] = subnode;
 
 	qsort(tbl, n, sizeof(*tbl), cmp_subnode);
@@ -598,7 +697,7 @@ static void sort_node(struct node *node)
 
 	sort_properties(node);
 	sort_subnodes(node);
-	for_each_child(node, c)
+	for_each_child_withdel(node, c)
 		sort_node(c);
 }
 

tests/run_tests.sh

@@ -367,6 +367,10 @@ dtc_tests () {
     run_dtc_test -I dts -O dtb -o dtc_tree1_merge_path.test.dtb test_tree1_merge_path.dts
     tree1_tests dtc_tree1_merge_path.test.dtb test_tree1.dtb
 
+    # Check prop/node delete functionality
+    run_dtc_test -I dts -O dtb -o dtc_tree1_delete.test.dtb test_tree1_delete.dts
+    tree1_tests dtc_tree1_delete.test.dtb
+
     # Check some checks
     check_tests dup-nodename.dts duplicate_node_names
     check_tests dup-propname.dts duplicate_property_names

tests/test_tree1.dts

@@ -1,38 +1,3 @@
 /dts-v1/;
 
-/memreserve/ 0xdeadbeef00000000 0x100000;
-/memreserve/ 123456789 010000;
-
-/ {
-	compatible = "test_tree1";
-	prop-int = <0xdeadbeef>;
-	prop-int64 = /bits/ 64 <0xdeadbeef01abcdef>;
-	prop-str = "hello world";
-
-	subnode@1 {
-		compatible = "subnode1";
-		prop-int = [deadbeef];
-
-		subsubnode {
-			compatible = "subsubnode1", "subsubnode";
-			prop-int = <0xdeadbeef>;
-		};
-
-		ss1 {
-		};
-	};
-
-	subnode@2 {
-		linux,phandle = <0x2000>;
-		prop-int = <123456789>;
-
-		ssn0: subsubnode@0 {
-			phandle = <0x2001>;
-			compatible = "subsubnode2", "subsubnode";
-			prop-int = <0726746425>;
-		};
-
-		ss2 {
-		};
-	};
-};
+/include/ "test_tree1_body.dtsi"

tests/test_tree1_body.dtsi

@@ -0,0 +1,36 @@
+/memreserve/ 0xdeadbeef00000000 0x100000;
+/memreserve/ 123456789 010000;
+
+/ {
+	compatible = "test_tree1";
+	prop-int = <0xdeadbeef>;
+	prop-int64 = /bits/ 64 <0xdeadbeef01abcdef>;
+	prop-str = "hello world";
+
+	subnode@1 {
+		compatible = "subnode1";
+		prop-int = [deadbeef];
+
+		subsubnode {
+			compatible = "subsubnode1", "subsubnode";
+			prop-int = <0xdeadbeef>;
+		};
+
+		ss1 {
+		};
+	};
+
+	subnode@2 {
+		linux,phandle = <0x2000>;
+		prop-int = <123456789>;
+
+		ssn0: subsubnode@0 {
+			phandle = <0x2001>;
+			compatible = "subsubnode2", "subsubnode";
+			prop-int = <0726746425>;
+		};
+
+		ss2 {
+		};
+	};
+};

tests/test_tree1_delete.dts

@@ -0,0 +1,68 @@
+/dts-v1/;
+
+/include/ "test_tree1_body.dtsi"
+
+/ {
+	nonexistant-property = <0xdeadbeef>;
+
+	nonexistant-subnode {
+		prop-int = <1>;
+	};
+
+	dellabel: deleted-by-label {
+		prop-int = <1>;
+	};
+
+	subnode@1 {
+		delete-this-str = "deadbeef";
+	};
+
+};
+
+/ {
+	/delete-property/ nonexistant-property;
+
+	/delete-node/ nonexistant-subnode;
+
+	subnode@1 {
+		/delete-property/ delete-this-str;
+	};
+};
+
+/delete-node/ &dellabel;
+
+/ {
+	/delete-property/ prop-str;
+};
+
+/ {
+	prop-str = "hello world";
+};
+
+/ {
+	subnode@1 {
+		/delete-node/ ss1;
+	};
+};
+
+/ {
+	subnode@1 {
+		ss1 {
+		};
+	};
+};
+
+/{
+	duplabel1: foo1 = "bar";
+	duplabel2: foo2 = "bar";
+};
+
+/{
+	duplabel1: baz1 = "qux";
+	duplabel2: baz2 = "qux";
+};
+
+/{
+	/delete-property/ foo1;
+	/delete-property/ baz2;
+};