[coreboot-gerrit] Patch set updated for coreboot: cbfstool: add extended attributes structure to cbfs_file

[Patrick Georgi (pgeorgi@google.com)]

Patrick Georgi (pgeorgi at google.com) just uploaded a new patch set to gerrit, which you can find at http://review.coreboot.org/10934

-gerrit

commit bd3cd72d26191f3925bc2319f6e27a4c57942616
Author: Patrick Georgi <pgeorgi at chromium.org>
Date:   Wed Jul 15 20:49:00 2015 +0200

    cbfstool: add extended attributes structure to cbfs_file
    
    This is a forward and backward compatible approach to extending the cbfs
    format. Unfortunately we forgot to add a header length or offset to the file
    name, making old implementations depend on it starting 24 bytes after the
    cbfs_file structure.
    
    To work around that, add another, extensible structure after the file name,
    and point to it through an offset, so we can add more variable length
    structures in the future when necessary.
    
    The offset field which points to the file data is adjusted appropriately and
    so old implementations still know where to find both any file's data and its
    successor in the directory.
    
    Files within CBFS that don't use advanced features remain fully usable by old
    implementations. Files that use advanced features still don't break the data
    structures.
    
    Change-Id: I325965286c44f31abd95df684d340cebb0e68b75
    Signed-off-by: Patrick Georgi <pgeorgi at chromium.org>
---
 util/cbfstool/cbfs.h       |  9 +++++++++
 util/cbfstool/cbfs_image.c | 11 +++++++++--
 2 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/util/cbfstool/cbfs.h b/util/cbfstool/cbfs.h
index e63db37..c7a5bd6 100644
--- a/util/cbfstool/cbfs.h
+++ b/util/cbfstool/cbfs.h
@@ -74,6 +74,7 @@ struct cbfs_file {
 	/* length of file data */
 	uint32_t len;
 	uint32_t type;
+	/* offset to struct cbfs_file_attributes or 0 */
 	uint32_t attributes_offset;
 	/* length of header incl. variable data */
 	uint32_t offset;
@@ -82,6 +83,11 @@ struct cbfs_file {
 
 _Static_assert(sizeof(struct cbfs_file) == 24, "cbfs_file size mismatch");
 
+struct cbfs_file_attributes {
+	/* size of this structure, to test if a given element is available */
+	uint32_t len;
+} __PACKED;
+
 struct cbfs_stage {
 	uint32_t compression;
 	uint64_t entry;
@@ -142,6 +148,9 @@ struct cbfs_payload {
 #define CBFS_COMPONENT_NULL 0xFFFFFFFF
 
 #define CBFS_SUBHEADER(_p) ( (void *) ((((uint8_t *) (_p)) + ntohl((_p)->offset))) )
+#define CBFS_FILE_ATTRIBUTES(_p) (((_p)->attributes_offset <= sizeof(_p)) ? NULL : \
+	(struct cbfs_file_attributes *)(((uint8_t *)(_p)) + ntohl((_p)->attributes_offset)))
+
 /* cbfs_image.c */
 uint32_t get_cbfs_entry_type(const char *name, uint32_t default_value);
 uint32_t get_cbfs_compression(const char *name, uint32_t unknown);
diff --git a/util/cbfstool/cbfs_image.c b/util/cbfstool/cbfs_image.c
index 6f028c8..48cf7b2 100644
--- a/util/cbfstool/cbfs_image.c
+++ b/util/cbfstool/cbfs_image.c
@@ -118,7 +118,8 @@ int cbfs_parse_comp_algo(const char *name)
 static size_t cbfs_calculate_file_header_size(const char *name)
 {
 	return (sizeof(struct cbfs_file) +
-		align_up(strlen(name) + 1, CBFS_FILENAME_ALIGN));
+		align_up(strlen(name) + 1, CBFS_FILENAME_ALIGN) +
+		sizeof(struct cbfs_file_attributes));
 }
 
 /* Only call on legacy CBFSes possessing a master header. */
@@ -1035,11 +1036,17 @@ int cbfs_create_empty_entry(struct cbfs_file *entry,
 	memcpy(entry->magic, CBFS_FILE_MAGIC, sizeof(entry->magic));
 	entry->type = htonl(CBFS_COMPONENT_NULL);
 	entry->len = htonl(len);
-	entry->attributes_offset = 0;
+	/* FIXME:
+	   move writing the offset fields to cbfs_calculate_file_header */
 	entry->offset = htonl(cbfs_calculate_file_header_size(name));
+	entry->attributes_offset = htonl(cbfs_calculate_file_header_size(name) -
+		sizeof(struct cbfs_file_attributes));
 	memset(entry->filename, 0, ntohl(entry->offset) - sizeof(*entry));
 	strcpy(entry->filename, name);
 	memset(CBFS_SUBHEADER(entry), CBFS_CONTENT_DEFAULT_VALUE, len);
+
+	struct cbfs_file_attributes *attr = CBFS_FILE_ATTRIBUTES(entry);
+	attr->len = sizeof(struct cbfs_file_attributes);
 	return 0;
 }