bdb: Add functions to get attributes of BDB components

These APIs return size and offsets of BDB components. They help code
look more descriptive.

BUG=none
BRANCH=none
TEST=make runtests

Change-Id: I29326e249d9f2b88d5716f878f8415703f63360c
Signed-off-by: Daisuke Nojiri <dnojiri@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/388813
Reviewed-by: Randall Spangler <rspangler@chromium.org>

firmware/bdb/bdb.c

@@ -5,7 +5,8 @@
  * Boot descriptor block firmware functions
  */
 
-#include <string.h>
+#include "2sysincludes.h"
+#include "2common.h"
 #include "2sha.h"
 #include "bdb.h"
 
@@ -196,6 +197,11 @@ const struct bdb_header *bdb_get_header(const void *buf)
 	return buf;
 }
 
+uint32_t bdb_size_of(const void *buf)
+{
+	return bdb_get_header(buf)->bdb_size;
+}
+
 const struct bdb_key *bdb_get_bdbkey(const void *buf)
 {
 	const struct bdb_header *h = bdb_get_header(buf);
@@ -223,6 +229,11 @@ const struct bdb_key *bdb_get_datakey(const void *buf)
 	return (const struct bdb_key *)(b8 + h->oem_area_0_size);
 }
 
+ptrdiff_t bdb_offset_of_datakey(const void *buf)
+{
+	return vb2_offset_of(buf, bdb_get_datakey(buf));
+}
+
 const struct bdb_sig *bdb_get_header_sig(const void *buf)
 {
 	const struct bdb_header *h = bdb_get_header(buf);
@@ -232,6 +243,11 @@ const struct bdb_sig *bdb_get_header_sig(const void *buf)
 	return (const struct bdb_sig *)(b8 + h->signed_size);
 }
 
+ptrdiff_t bdb_offset_of_header_sig(const void *buf)
+{
+	return vb2_offset_of(buf, bdb_get_header_sig(buf));
+}
+
 const struct bdb_data *bdb_get_data(const void *buf)
 {
 	const struct bdb_sig *s = bdb_get_header_sig(buf);
@@ -241,6 +257,11 @@ const struct bdb_data *bdb_get_data(const void *buf)
 	return (const struct bdb_data *)(b8 + s->struct_size);
 }
 
+ptrdiff_t bdb_offset_of_data(const void *buf)
+{
+	return vb2_offset_of(buf, bdb_get_data(buf));
+}
+
 const void *bdb_get_oem_area_1(const void *buf)
 {
 	const struct bdb_data *p = bdb_get_data(buf);

firmware/bdb/bdb.h

@@ -9,6 +9,8 @@
 #define VBOOT_REFERENCE_BDB_H_
 
 #include <stdlib.h>
+#include <stddef.h>
+
 #include "bdb_struct.h"
 
 /*****************************************************************************/
@@ -153,6 +155,24 @@ const void *bdb_get_oem_area_1(const void *buf);
 const struct bdb_hash *bdb_get_hash(const void *buf, enum bdb_data_type type);
 const struct bdb_sig *bdb_get_data_sig(const void *buf);
 
+/**
+ * Functions to calculate size of BDB components
+ *
+ * @param buf		Pointer to BDB buffer
+ * @return		Size of the component
+ */
+uint32_t bdb_size_of(const void *buf);
+
+/**
+ * Functions to calculate offset of BDB components
+ *
+ * @param buf		Pointer to BDB buffer
+ * @return		Offset of the component
+ */
+ptrdiff_t bdb_offset_of_datakey(const void *buf);
+ptrdiff_t bdb_offset_of_header_sig(const void *buf);
+ptrdiff_t bdb_offset_of_data(const void *buf);
+
 /*****************************************************************************/
 /* Functions probably provided by the caller */