text: /*
   * linux/fs/ext4/xattr_trusted.c
   * Handler for trusted extended attributes.
   *
   * Copyright (C) 2003 by Andreas Gruenbacher, <a.gruenbacher@computer.org>
   */
  
  #include <linux/module.h>
  #include <linux/string.h>
  #include <linux/capability.h>
  #include <linux/fs.h>
  #include <linux/smp_lock.h>
  #include <linux/ext4_jbd2.h>
  #include <linux/ext4_fs.h>
  #include "xattr.h"
  
  #define XATTR_TRUSTED_PREFIX "trusted."
  
  static size_t
  ext4_xattr_trusted_list(struct inode *inode, char *list, size_t list_size,
  			const char *name, size_t name_len)
  {
  	const size_t prefix_len = sizeof(XATTR_TRUSTED_PREFIX)-1;
  	const size_t total_len = prefix_len + name_len + 1;
  
  	if (!capable(CAP_SYS_ADMIN))
  		return 0;
  
  	if (list && total_len <= list_size) {
  		memcpy(list, XATTR_TRUSTED_PREFIX, prefix_len);
  		memcpy(list+prefix_len, name, name_len);
  		list[prefix_len + name_len] = '\0';
  	}
  	return total_len;
  }
  
  static int
  ext4_xattr_trusted_get(struct inode *inode, const char *name,
  		       void *buffer, size_t size)
  {
  	if (strcmp(name, "") == 0)
  		return -EINVAL;
  	return ext4_xattr_get(inode, EXT4_XATTR_INDEX_TRUSTED, name,
  			      buffer, size);
  }
  
  static int
  ext4_xattr_trusted_set(struct inode *inode, const char *name,
  		       const void *value, size_t size, int flags)
  {
  	if (strcmp(name, "") == 0)
  		return -EINVAL;
  	return ext4_xattr_set(inode, EXT4_XATTR_INDEX_TRUSTED, name,
  			      value, size, flags);
  }
  
  struct xattr_handler ext4_xattr_trusted_handler = {
  	.prefix	= XATTR_TRUSTED_PREFIX,
  	.list	= ext4_xattr_trusted_list,
  	.get	= ext4_xattr_trusted_get,
  	.set	= ext4_xattr_trusted_set,
  };
  