linux-kernel - [PATCH v3 1/2] bootconfig: Prohibit re-defining value on same key

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Message-Id: <158227282199.12842.10110929876059658601.stgit@devnote2>
Date:   Fri, 21 Feb 2020 17:13:42 +0900
From:   Masami Hiramatsu <mhiramat@...nel.org>
To:     Steven Rostedt <rostedt@...dmis.org>
Cc:     Geert Uytterhoeven <geert@...ux-m68k.org>,
        Borislav Petkov <bp@...en8.de>,
        LKML <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>
Subject: [PATCH v3 1/2] bootconfig: Prohibit re-defining value on same key

Currently, bootconfig adds new value on the existing key
to the tail of an array. But this looks a bit confusing
because admin can rewrite original value in same config
file easily.

This rejects following value re-definition.

  key = value1
  ...
  key = value2

You should rewrite value1 to value2 in this case.

Signed-off-by: Masami Hiramatsu <mhiramat@...nel.org>
---
 Documentation/admin-guide/bootconfig.rst   |   11 ++++++++++-
 lib/bootconfig.c                           |   13 ++++++++-----
 tools/bootconfig/samples/bad-samekey.bconf |    6 ++++++
 3 files changed, 24 insertions(+), 6 deletions(-)
 create mode 100644 tools/bootconfig/samples/bad-samekey.bconf

diff --git a/Documentation/admin-guide/bootconfig.rst b/Documentation/admin-guide/bootconfig.rst
index dfeffa73dca3..9ee7650b7817 100644
--- a/Documentation/admin-guide/bootconfig.rst
+++ b/Documentation/admin-guide/bootconfig.rst
@@ -62,7 +62,16 @@ Or more shorter, written as following::
 In both styles, same key words are automatically merged when parsing it
 at boot time. So you can append similar trees or key-values.
 
-Note that a sub-key and a value can not co-exist under a parent key.
+Same-key Values
+---------------
+
+It is prohibited that two or more values or arraies share a same-key.
+For example,::
+
+ foo = bar, baz
+ foo = qux  # !ERROR! we can not re-define same key
+
+Also, a sub-key and a value can not co-exist under a parent key.
 For example, following config is NOT allowed.::
 
  foo = value1
diff --git a/lib/bootconfig.c b/lib/bootconfig.c
index 54ac623ca781..2ef304db31f2 100644
--- a/lib/bootconfig.c
+++ b/lib/bootconfig.c
@@ -581,7 +581,7 @@ static int __init __xbc_parse_keys(char *k)
 static int __init xbc_parse_kv(char **k, char *v)
 {
 	struct xbc_node *prev_parent = last_parent;
-	struct xbc_node *node, *child;
+	struct xbc_node *child;
 	char *next;
 	int c, ret;
 
@@ -590,15 +590,18 @@ static int __init xbc_parse_kv(char **k, char *v)
 		return ret;
 
 	child = xbc_node_get_child(last_parent);
-	if (child && xbc_node_is_key(child))
-		return xbc_parse_error("Value is mixed with subkey", v);
+	if (child) {
+		if (xbc_node_is_key(child))
+			return xbc_parse_error("Value is mixed with subkey", v);
+		else
+			return xbc_parse_error("Value is redefined", v);
+	}
 
 	c = __xbc_parse_value(&v, &next);
 	if (c < 0)
 		return c;
 
-	node = xbc_add_sibling(v, XBC_VALUE);
-	if (!node)
+	if (!xbc_add_sibling(v, XBC_VALUE))
 		return -ENOMEM;
 
 	if (c == ',') {	/* Array */
diff --git a/tools/bootconfig/samples/bad-samekey.bconf b/tools/bootconfig/samples/bad-samekey.bconf
new file mode 100644
index 000000000000..e8d983a4563c
--- /dev/null
+++ b/tools/bootconfig/samples/bad-samekey.bconf
@@ -0,0 +1,6 @@
+# Same key value is not allowed
+key {
+	foo = value
+	bar = value2
+}
+key.foo = value