/*
   * Copyright (C) 2012 Red Hat, Inc.
   * Copyright (C) 2012 Jeremy Kerr <jeremy.kerr@canonical.com>
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License version 2 as
   * published by the Free Software Foundation.
   */
  
  #include <linux/efi.h>
  #include <linux/fs.h>
  #include <linux/ctype.h>
  #include <linux/slab.h>
  
  #include "internal.h"
  
  struct inode *efivarfs_get_inode(struct super_block *sb,
  				const struct inode *dir, int mode, dev_t dev)
  {
  	struct inode *inode = new_inode(sb);
  
  	if (inode) {
  		inode->i_ino = get_next_ino();
  		inode->i_mode = mode;
  		inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
  		switch (mode & S_IFMT) {
  		case S_IFREG:
  			inode->i_fop = &efivarfs_file_operations;
  			break;
  		case S_IFDIR:
  			inode->i_op = &efivarfs_dir_inode_operations;
  			inode->i_fop = &simple_dir_operations;
  			inc_nlink(inode);
  			break;
  		}
  	}
  	return inode;
  }
  
  /*
   * Return true if 'str' is a valid efivarfs filename of the form,
   *
   *	VariableName-12345678-1234-1234-1234-1234567891bc
   */
  bool efivarfs_valid_name(const char *str, int len)
  {
  	static const char dashes[EFI_VARIABLE_GUID_LEN] = {
  		[8] = 1, [13] = 1, [18] = 1, [23] = 1
  	};
  	const char *s = str + len - EFI_VARIABLE_GUID_LEN;
  	int i;
  
  	/*
  	 * We need a GUID, plus at least one letter for the variable name,
  	 * plus the '-' separator
  	 */
  	if (len < EFI_VARIABLE_GUID_LEN + 2)
  		return false;
  
  	/* GUID must be preceded by a '-' */
  	if (*(s - 1) != '-')
  		return false;
  
  	/*
  	 * Validate that 's' is of the correct format, e.g.
  	 *
  	 *	12345678-1234-1234-1234-123456789abc
  	 */
  	for (i = 0; i < EFI_VARIABLE_GUID_LEN; i++) {
  		if (dashes[i]) {
  			if (*s++ != '-')
  				return false;
  		} else {
  			if (!isxdigit(*s++))
  				return false;
  		}
  	}
  
  	return true;
  }
  
  static void efivarfs_hex_to_guid(const char *str, efi_guid_t *guid)
  {
  	guid->b[0] = hex_to_bin(str[6]) << 4 | hex_to_bin(str[7]);
  	guid->b[1] = hex_to_bin(str[4]) << 4 | hex_to_bin(str[5]);
  	guid->b[2] = hex_to_bin(str[2]) << 4 | hex_to_bin(str[3]);
  	guid->b[3] = hex_to_bin(str[0]) << 4 | hex_to_bin(str[1]);
  	guid->b[4] = hex_to_bin(str[11]) << 4 | hex_to_bin(str[12]);
  	guid->b[5] = hex_to_bin(str[9]) << 4 | hex_to_bin(str[10]);
  	guid->b[6] = hex_to_bin(str[16]) << 4 | hex_to_bin(str[17]);
  	guid->b[7] = hex_to_bin(str[14]) << 4 | hex_to_bin(str[15]);
  	guid->b[8] = hex_to_bin(str[19]) << 4 | hex_to_bin(str[20]);
  	guid->b[9] = hex_to_bin(str[21]) << 4 | hex_to_bin(str[22]);
  	guid->b[10] = hex_to_bin(str[24]) << 4 | hex_to_bin(str[25]);
  	guid->b[11] = hex_to_bin(str[26]) << 4 | hex_to_bin(str[27]);
  	guid->b[12] = hex_to_bin(str[28]) << 4 | hex_to_bin(str[29]);
  	guid->b[13] = hex_to_bin(str[30]) << 4 | hex_to_bin(str[31]);
  	guid->b[14] = hex_to_bin(str[32]) << 4 | hex_to_bin(str[33]);
  	guid->b[15] = hex_to_bin(str[34]) << 4 | hex_to_bin(str[35]);
  }
  
  static int efivarfs_create(struct inode *dir, struct dentry *dentry,
  			  umode_t mode, bool excl)
  {
  	struct inode *inode;
  	struct efivar_entry *var;
  	int namelen, i = 0, err = 0;
  
  	if (!efivarfs_valid_name(dentry->d_name.name, dentry->d_name.len))
  		return -EINVAL;
  
  	inode = efivarfs_get_inode(dir->i_sb, dir, mode, 0);
  	if (!inode)
  		return -ENOMEM;
  
  	var = kzalloc(sizeof(struct efivar_entry), GFP_KERNEL);
  	if (!var) {
  		err = -ENOMEM;
  		goto out;
  	}
  
  	/* length of the variable name itself: remove GUID and separator */
  	namelen = dentry->d_name.len - EFI_VARIABLE_GUID_LEN - 1;
  
  	efivarfs_hex_to_guid(dentry->d_name.name + namelen + 1,
  			&var->var.VendorGuid);
  
  	for (i = 0; i < namelen; i++)
  		var->var.VariableName[i] = dentry->d_name.name[i];
  
  	var->var.VariableName[i] = '\0';
  
  	inode->i_private = var;
  
  	efivar_entry_add(var, &efivarfs_list);
  	d_instantiate(dentry, inode);
  	dget(dentry);
  out:
  	if (err) {
  		kfree(var);
  		iput(inode);
  	}
  	return err;
  }
  
  static int efivarfs_unlink(struct inode *dir, struct dentry *dentry)
  {
  	struct efivar_entry *var = dentry->d_inode->i_private;
  
  	if (efivar_entry_delete(var))
  		return -EINVAL;
  
  	drop_nlink(dentry->d_inode);
  	dput(dentry);
  	return 0;
  };
  
  const struct inode_operations efivarfs_dir_inode_operations = {
  	.lookup = simple_lookup,
  	.unlink = efivarfs_unlink,
  	.create = efivarfs_create,
  };