[yocto] [meta-selinux][RFC 09/10] e2fsprogs: Add patch to hold xattr header and block number in a structure for the cache.

[Philip Tricca]

Signed-off-by: Philip Tricca <flihp at twobit.us>
---
 .../misc-xattr-create-xattr-block-node.patch       | 126 +++++++++++++++++++++
 .../e2fsprogs/e2fsprogs_1.42.9.bbappend            |   1 +
 2 files changed, 127 insertions(+)
 create mode 100644 recipes-devtools/e2fsprogs/e2fsprogs/misc-xattr-create-xattr-block-node.patch

diff --git a/recipes-devtools/e2fsprogs/e2fsprogs/misc-xattr-create-xattr-block-node.patch b/recipes-devtools/e2fsprogs/e2fsprogs/misc-xattr-create-xattr-block-node.patch
new file mode 100644
index 0000000..cff47ed
--- /dev/null
+++ b/recipes-devtools/e2fsprogs/e2fsprogs/misc-xattr-create-xattr-block-node.patch
@@ -0,0 +1,126 @@
+Add two new functions to manage a cache of xattr blocks as well as a new struct
+to build a linked list of xattr blocks.
+
+xattr_add_block: Adds a block to the cache. This function is supplied with a
+pointer to the head of a linked list of xattr blocks and an xattr block to add.
+The purpose of this cache is to allow sharing of what would otherwise be
+duplicate xattr blocks and so duplicates are not allowed in this cache. If an
+identical block is already in the cache a pointer to this block will be
+returned.
+
+xattr_rm_block: Removes a block from the cache. This function is supplied with
+a pointer to the cache and a node that shall be removed from the cache. The
+cache is searched for the node and the node is removed if found.
+
+Both functions are integrated into the 'set_inode_xattr'. Here the logic is
+rearranged to cope with associating preexisting xattr blocks with inodes as
+well as creating new blocks when necessary.
+
+Signed-off-by: Philip Tricca <flihp at twobit.us>
+
+Index: e2fsprogs-1.42.9/misc/xattr.c
+===================================================================
+--- e2fsprogs-1.42.9.orig/misc/xattr.c
++++ e2fsprogs-1.42.9/misc/xattr.c
+@@ -25,6 +25,19 @@
+ #define XATTR_STDERR(fmt, args...) do {} while (0)
+ #endif
+ 
++/* nodes for simple linked list to track xattr blocks, calling it a cache
++ * would be a stretch ...
++ */
++typedef struct xattr_node xattr_node_t;
++
++struct xattr_node {
++	struct ext2_ext_attr_header *header;
++	blk_t block;
++	struct xattr_node *next;
++};
++
++xattr_node_t *xattr_list_head = NULL;
++
+ /* structure for mapping xattr name prefix data */
+ typedef struct xattr_prefix {
+ 	int index;
+@@ -48,6 +61,17 @@ xattr_prefix_t xattr_prefixes [] = {
+ 	{ 0 },
+ };
+ 
++/* free xattr node and the buffer holding the xattr block */
++static void
++xattr_free_node (xattr_node_t *node)
++{
++	if (node) {
++		if (node->header)
++			free (node->header);
++		free (node);
++	}
++}
++
+ /* Free remaining resources after all files have been processed. */
+ void
+ xattr_cleanup ()
+@@ -260,6 +284,28 @@ out:
+ 	return ret;
+ }
+ 
++/* Add an xattr node to the list specified by head. This function will update
++ * head as necessary. It will return a pointer to the xattr_node_t added to the
++ * list. In the event that an identical xattr block is already on the list this
++ * function will return a pointer to the pre-existing node.
++ */
++static xattr_node_t*
++xattr_add_block (xattr_node_t **head, xattr_node_t *node)
++{
++	XATTR_STDERR ("Adding xattr to the the node list.\n");
++	return node;
++}
++
++/* Remove xattr node from list. Returns pointer to the node being removed.
++ * NOTE: We're not comparing the xattr blocks, just the nodes.
++ */
++static xattr_node_t*
++xattr_rm_block (xattr_node_t **head, xattr_node_t *node)
++{
++	XATTR_STDERR ("Removing xattr from the node list.\n");
++	return node;
++}
++
+ /* This is the entry point to the xattr module. This function copies the xattrs
+  * from the file at 'path' to the file system object at 'ino'.
+  *
+@@ -274,16 +320,21 @@ set_inode_xattr (ext2_filsys fs, ext2_in
+ 	errcode_t ret = 0;
+ 	char *buf = NULL;
+ 	struct ext2_inode inode = { 0 };
+-	blk_t block = 0;
+-	struct ext2_ext_attr_header *header = NULL;
++	xattr_node_t *node = NULL, *node_tmp = NULL;
+ 	uint32_t newcount = 0;
+ 
+ 	XATTR_STDERR ("Copying xattrs from %s to inode 0x%x.\n", path, ino);
++	/* Create an xattr_node_t for it and add it to the cache if appropriate */
++	if (!(node = calloc (1, sizeof (xattr_node_t)))) {
++		com_err (__func__, errno, "calloc");
++		ret = errno;
++		goto out;
++	}
+ 	/* Populate the xattr block for the file at path */
+-	if (ret = xattr_build_block (path, &header, fs->blocksize)) {
++	if (ret = xattr_build_block (path, &(node->header), fs->blocksize)) {
+ 		goto out;
+ 	}
+-	if (header == NULL) {
++	if (node->header == NULL) {
+ 		XATTR_STDERR ("set_inode_xattrs: no xattrs for %s\n", path);
+ 		goto out;
+ 	}
+@@ -321,7 +372,6 @@ set_inode_xattr (ext2_filsys fs, ext2_in
+ 	if (ret = ext2fs_write_inode (fs, ino, &inode))
+ 		com_err(__func__, ret, "ext2fs_write_inode: returned %d", ret);
+ out:
+-	if (header)
+-		free (header);
++	xattr_free_node (node);
+ 	return ret;
+ }
diff --git a/recipes-devtools/e2fsprogs/e2fsprogs_1.42.9.bbappend b/recipes-devtools/e2fsprogs/e2fsprogs_1.42.9.bbappend
index d2cefbf..241a9bf 100644
--- a/recipes-devtools/e2fsprogs/e2fsprogs_1.42.9.bbappend
+++ b/recipes-devtools/e2fsprogs/e2fsprogs_1.42.9.bbappend
@@ -7,4 +7,5 @@ SRC_URI += " \
     file://misc-create_inode.c-label-fs-objects.patch \
     file://lib-ext2fs-ext2_ext_attr.h-add-xattr-index.patch \
     file://misc-xattr-create-xattr-block.patch \
+    file://misc-xattr-create-xattr-block-node.patch \
 "
-- 
2.1.4