From 58aec3c59a53147c7d924c823f7405218fb5f555 Mon Sep 17 00:00:00 2001
From: Felix Fietkau <nbd@openwrt.org>
Date: Wed, 12 Mar 2014 20:08:27 +0100
Subject: [PATCH] blobmsg: allow data/length iterator/accessor functions to
 work on non-blobmsg elements

This primarily helps with simplifying the ubus APIs.
blobmsg header presence is indicated by the BLOB_ATTR_EXTENDED bit in
the id_len field.

This changes the format ABI, but not the API.

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
---
 blob.c    | 5 ++---
 blob.h    | 9 ++++++++-
 blobmsg.c | 1 +
 blobmsg.h | 7 ++++++-
 4 files changed, 17 insertions(+), 5 deletions(-)

diff --git a/blob.c b/blob.c
index faa3bb8..2da7cac 100644
--- a/blob.c
+++ b/blob.c
@@ -115,10 +115,9 @@ blob_fill_pad(struct blob_attr *attr)
 void
 blob_set_raw_len(struct blob_attr *attr, unsigned int len)
 {
-	int id = blob_id(attr);
 	len &= BLOB_ATTR_LEN_MASK;
-	len |= (id << BLOB_ATTR_ID_SHIFT) & BLOB_ATTR_ID_MASK;
-	attr->id_len = cpu_to_be32(len);
+	attr->id_len &= ~cpu_to_be32(BLOB_ATTR_LEN_MASK);
+	attr->id_len |= cpu_to_be32(len);
 }
 
 struct blob_attr *
diff --git a/blob.h b/blob.h
index fa430a8..37a572b 100644
--- a/blob.h
+++ b/blob.h
@@ -42,10 +42,11 @@ enum {
 	BLOB_ATTR_LAST
 };
 
-#define BLOB_ATTR_ID_MASK  0xff000000
+#define BLOB_ATTR_ID_MASK  0x7f000000
 #define BLOB_ATTR_ID_SHIFT 24
 #define BLOB_ATTR_LEN_MASK 0x00ffffff
 #define BLOB_ATTR_ALIGN    4
+#define BLOB_ATTR_EXTENDED 0x80000000
 
 struct blob_attr {
 	uint32_t id_len;
@@ -85,6 +86,12 @@ blob_id(const struct blob_attr *attr)
 	return id;
 }
 
+static inline bool
+blob_is_extended(const struct blob_attr *attr)
+{
+	return !!(attr->id_len & cpu_to_be32(BLOB_ATTR_EXTENDED));
+}
+
 /*
  * blob_len: returns the length of the attribute's payload
  */
diff --git a/blobmsg.c b/blobmsg.c
index 3076620..47ee9e7 100644
--- a/blobmsg.c
+++ b/blobmsg.c
@@ -181,6 +181,7 @@ blobmsg_new(struct blob_buf *buf, int type, const char *name, int payload_len, v
 	if (!attr)
 		return NULL;
 
+	attr->id_len |= be32_to_cpu(BLOB_ATTR_EXTENDED);
 	hdr = blob_data(attr);
 	hdr->namelen = cpu_to_be16(namelen);
 	strcpy((char *) hdr->name, (const char *)name);
diff --git a/blobmsg.h b/blobmsg.h
index 4619643..e9e0e6e 100644
--- a/blobmsg.h
+++ b/blobmsg.h
@@ -65,7 +65,12 @@ static inline int blobmsg_type(const struct blob_attr *attr)
 static inline void *blobmsg_data(const struct blob_attr *attr)
 {
 	struct blobmsg_hdr *hdr = (struct blobmsg_hdr *) blob_data(attr);
-	return (char *) hdr + blobmsg_hdrlen(be16_to_cpu(hdr->namelen));
+	char *data = blob_data(attr);
+
+	if (blob_is_extended(attr))
+		data += blobmsg_hdrlen(be16_to_cpu(hdr->namelen));
+
+	return data;
 }
 
 static inline int blobmsg_data_len(const struct blob_attr *attr)