-
-static const char *
-strcmp_prefix(const char *a, const char *a_prefix)
-{
- while (*a_prefix && *a == *a_prefix) {
- a++;
- a_prefix++;
- }
- return *a_prefix ? NULL : a;
-}
-
-/*
- * In order to implement different sets of xattr operations for each xattr
- * prefix with the generic xattr API, a filesystem should create a
- * null-terminated array of struct xattr_handler (one for each prefix) and
- * hang a pointer to it off of the s_xattr field of the superblock.
- *
- * The generic_fooxattr() functions will use this list to dispatch xattr
- * operations to the correct xattr_handler.
- */
-#define for_each_xattr_handler(handlers, handler) \
- if (handlers) \
- for ((handler) = *(handlers)++; \
- (handler) != NULL; \
- (handler) = *(handlers)++)
-
-/*
- * Find the xattr_handler with the matching prefix.
- */
-static const struct xattr_handler *
-xattr_resolve_name(const struct xattr_handler **handlers, const char **name)
-{
- const struct xattr_handler *handler;
-
- if (!*name)
- return ERR_PTR(-EINVAL);
-
- for_each_xattr_handler(handlers, handler) {
- const char *n;
-
- n = strcmp_prefix(*name, xattr_prefix(handler));
- if (n) {
- if (!handler->prefix ^ !*n) {
- if (*n)
- continue;
- return ERR_PTR(-EINVAL);
- }
- *name = n;
- return handler;
- }
- }
- return ERR_PTR(-EOPNOTSUPP);
-}
-
-/*
- * Find the handler for the prefix and dispatch its get() operation.
- */
-ssize_t
-generic_getxattr(struct dentry *dentry, struct inode *inode,
- const char *name, void *buffer, size_t size)
-{
- const struct xattr_handler *handler;
-
- handler = xattr_resolve_name(dentry->d_sb->s_xattr, &name);
- if (IS_ERR(handler))
- return PTR_ERR(handler);
- return handler->get(handler, dentry, inode,
- name, buffer, size);
-}
-