linux-master/fs/xattr.c

3   File: fs/xattr.c
15 #include <linux/xattr.h>
41  * In order to implement different sets of xattr operations for each xattr
84  * may_write_xattr - check whether inode allows writing xattr
86  * @inode: the inode on which to set an xattr
211  *  @name: xattr name to set
267  *  @name: xattr name to set
369  * before retrieving the extended attribute.  The xattr value buffer should
461  * vfs_listxattr - retrieve \0 separated list of xattr names
462  * @dentry: the dentry from whose inode the xattr names are retrieved
463  * @list: buffer to store xattr names into
529  *  @name: name of xattr to remove
988  * generic_listxattr - run through a dentry's xattr list() operations
1023  * The get and set xattr handler operations are called with the remainder of
1028  * Note: the list xattr handler operation when called from the vfs is passed a
1042  * simple_xattr_space - estimate the memory used by a simple xattr
1043  * @name: the full name of the xattr
1050  * Return: The approximate number of bytes of memory used by such an xattr.
1062  * simple_xattr_free - free an xattr object
1063  * @xattr: the xattr object
1065  * Free the xattr object. Can handle @xattr being NULL.
1067 void simple_xattr_free(struct simple_xattr *xattr)
1069 	if (xattr)
1070 		kfree(xattr->name);
1071 	kvfree(xattr);
1075  * simple_xattr_alloc - allocate new xattr object
1076  * @value: value of the xattr object
1079  * Allocate a new xattr object and initialize respective members. The caller is
1080  * responsible for handling the name of the xattr.
1082  * Return: On success a new xattr object is returned. On failure NULL is
1105  * rbtree_simple_xattr_cmp - compare xattr name with current rbtree xattr entry
1106  * @key: xattr name
1109  * Compare the xattr name with the xattr name attached to @node in the rbtree.
1112  * if the xattr attached to @node matches @key.
1117 	const struct simple_xattr *xattr;
1119 	xattr = rb_entry(node, struct simple_xattr, rb_node);
1120 	return strcmp(xattr->name, xattr_name);
1124  * rbtree_simple_xattr_node_cmp - compare two xattr rbtree nodes
1128  * Compare the xattr attached to @new_node with the xattr attached to @node.
1131  * if the xattr attached to @new_node matches the xattr attached to @node.
1136 	struct simple_xattr *xattr;
1137 	xattr = rb_entry(new_node, struct simple_xattr, rb_node);
1138 	return rbtree_simple_xattr_cmp(xattr->name, node);
1142  * simple_xattr_get - get an xattr object
1143  * @xattrs: the header of the xattr object
1144  * @name: the name of the xattr to retrieve
1148  * Try to find and retrieve the xattr object associated with @name.
1149  * If @buffer is provided store the value of @xattr in @buffer
1153  * Return: On success the length of the xattr value is returned. On error a
1159 	struct simple_xattr *xattr = NULL;
1166 		xattr = rb_entry(rbp, struct simple_xattr, rb_node);
1167 		ret = xattr->size;
1169 			if (size < xattr->size)
1172 				memcpy(buffer, xattr->value, xattr->size);
1180  * simple_xattr_set - set an xattr object
1181  * @xattrs: the header of the xattr object
1182  * @name: the name of the xattr to retrieve
1183  * @value: the value to store along the xattr
1185  * @flags: the flags determining how to set the xattr
1187  * Set a new xattr object.
1188  * If @value is passed a new xattr object will be allocated. If XATTR_REPLACE
1189  * is specified in @flags a matching xattr object for @name must already exist.
1190  * If it does it will be replaced with the new xattr object. If it doesn't we
1191  * fail. If XATTR_CREATE is specified and a matching xattr does already exist
1192  * we fail. If it doesn't we create a new xattr. If @flags is zero we simply
1193  * insert the new xattr replacing any existing one.
1195  * If @value is empty and a matching xattr object is found we delete it if
1198  * If @value is empty and no matching xattr object for @name is found we do
1202  * Return: On success, the removed or replaced xattr is returned, to be freed
1242 		/* Fail if XATTR_CREATE is requested and the xattr exists. */
1254 		/* Fail if XATTR_REPLACE is requested but no xattr is found. */
1271 		 * old or new xattr exist then we don't need to do anything.
1289  * simple_xattr_list - list all xattr objects
1291  * @xattrs: the header of the xattr object
1299  * Note, the number of xattr names that can be listed with listxattr(2) is
1301  * then vfs_listxattr() caps it to XATTR_LIST_MAX and if more xattr names
1311 	struct simple_xattr *xattr;
1322 		xattr = rb_entry(rbp, struct simple_xattr, rb_node);
1325 		if (!trusted && xattr_is_trusted(xattr->name))
1328 		err = xattr_list_one(&buffer, &remaining_size, xattr->name);
1338  * rbtree_simple_xattr_less - compare two xattr rbtree nodes
1342  * Compare the xattr attached to @new_node with the xattr attached to @node.
1354  * simple_xattr_add - add xattr objects
1355  * @xattrs: the header of the xattr object
1356  * @new_xattr: the xattr object to add
1358  * Add an xattr object to @xattrs. This assumes no replacement or removal
1371  * simple_xattrs_init - initialize new xattr header
1374  * Initialize relevant fields of a an xattr header.
1384  * @xattrs: xattr header whose xattrs to destroy
1387  * Destroy all xattrs in @xattr. When this is called no one can hold a
1398 		struct simple_xattr *xattr;
1402 		xattr = rb_entry(rbp, struct simple_xattr, rb_node);
1403 		rb_erase(&xattr->rb_node, &xattrs->rb_root);
1405 			*freed_space += simple_xattr_space(xattr->name,
1406 							   xattr->size);
1407 		simple_xattr_free(xattr);