[PATCH 1/3] tools/bootconfig: Close only opened braces in compact output

[Eduardo Mucelli Rezende Oliveira <edumucelli@gmail.com>]

A key may have both a value and subkeys. When it has only one subkey,
xbc_show_compact_tree() can print that subkey using dotted notation
without opening a brace. During backtracking, however, it treats the
value node followed by a subkey as evidence that a brace was opened.

For example, a.b=v, a.b.c=w and a.z=q are printed with the brace for a
closed before z. Reading that output back changes a.z into the root key
z, silently changing the configuration.

Remember the nodes for which opening braces were actually printed and
close a brace only when backtracking through the matching node. Extend
the existing mixed-value/subkey sample to cover a sibling after a valued
parent with one subkey.

Fixes: e5efaeb8a8f5 ("bootconfig: Support mixing a value and subkeys under a key")
Signed-off-by: Eduardo Mucelli Rezende Oliveira <edumucelli@gmail.com>
---
With this valid configuration:

  a.b = v
  a.b.c = w
  a.z = q

the original compact output closes the brace for a before printing z.
Reparsing it turns a.z into the root key z. Values and subkeys under
the same key are allowed by the documented syntax:
https://docs.kernel.org/admin-guide/bootconfig.html#same-key-values

I checked parser round trips for valued parents, bare subkeys, arrays,
deeper trees and a test initrd image. All 94 focused checks pass with
the fix, independently and in the combined series. The full bootconfig
test suite also passes.

 tools/bootconfig/main.c                           | 15 +++++++--------
 tools/bootconfig/samples/exp-good-mixed-kv1.bconf |  5 +++++
 tools/bootconfig/samples/good-mixed-kv1.bconf     |  5 +++++
 3 files changed, 17 insertions(+), 8 deletions(-)

diff --git a/tools/bootconfig/main.c b/tools/bootconfig/main.c
index 56d76bdeaa09..1bab0e685e2d 100644
--- a/tools/bootconfig/main.c
+++ b/tools/bootconfig/main.c
@@ -71,6 +71,7 @@ static int xbc_show_value(struct xbc_node *node, bool semicolon)
 static void xbc_show_compact_tree(void)
 {
 	struct xbc_node *node, *cnode = NULL, *vnode;
+	struct xbc_node *parent[XBC_DEPTH_MAX];
 	int depth = 0, i;
 
 	node = xbc_root_node();
@@ -100,7 +101,7 @@ static void xbc_show_compact_tree(void)
 		}
 		if (cnode && xbc_node_is_key(cnode)) {
 			printf("%s {\n", xbc_node_get_data(node));
-			depth++;
+			parent[depth++] = node;
 			node = cnode;
 			cnode = NULL;
 			continue;
@@ -128,14 +129,12 @@ static void xbc_show_compact_tree(void)
 			node = xbc_node_get_parent(node);
 			if (!node)
 				return;
-			if (!xbc_node_get_child(node)->next)
+			if (!depth || parent[depth - 1] != node)
 				continue;
-			if (depth) {
-				depth--;
-				for (i = 0; i < depth; i++)
-					printf("\t");
-				printf("}\n");
-			}
+			depth--;
+			for (i = 0; i < depth; i++)
+				printf("\t");
+			printf("}\n");
 		}
 		node = xbc_node_get_next(node);
 	}
diff --git a/tools/bootconfig/samples/exp-good-mixed-kv1.bconf b/tools/bootconfig/samples/exp-good-mixed-kv1.bconf
index 8346287d9251..0b8b2f59da31 100644
--- a/tools/bootconfig/samples/exp-good-mixed-kv1.bconf
+++ b/tools/bootconfig/samples/exp-good-mixed-kv1.bconf
@@ -1,2 +1,7 @@
 key = "value";
 key.subkey = "another-value";
+a {
+	b = "v";
+	b.c = "w";
+	z = "q";
+}
diff --git a/tools/bootconfig/samples/good-mixed-kv1.bconf b/tools/bootconfig/samples/good-mixed-kv1.bconf
index 1761547dd05c..35442ee62b75 100644
--- a/tools/bootconfig/samples/good-mixed-kv1.bconf
+++ b/tools/bootconfig/samples/good-mixed-kv1.bconf
@@ -1,3 +1,8 @@
 # value -> subkey pattern
 key = value
 key.subkey = another-value
+
+# A valued parent with one subkey must not close its enclosing brace.
+a.b = v
+a.b.c = w
+a.z = q
-- 
2.53.0