LXR linux/lib/uuid.c

   1/*
   2 * Unified UUID/GUID definition
   3 *
   4 * Copyright (C) 2009, 2016 Intel Corp.
   5 *      Huang Ying <ying.huang@intel.com>
   6 *
   7 * This program is free software; you can redistribute it and/or
   8 * modify it under the terms of the GNU General Public License version
   9 * 2 as published by the Free Software Foundation;
  10 *
  11 * This program is distributed in the hope that it will be useful,
  12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 * GNU General Public License for more details.
  15 */
  16
  17#include <linux/kernel.h>
  18#include <linux/ctype.h>
  19#include <linux/errno.h>
  20#include <linux/export.h>
  21#include <linux/uuid.h>
  22#include <linux/random.h>
  23
  24const guid_t guid_null;
  25EXPORT_SYMBOL(guid_null);
  26const uuid_t uuid_null;
  27EXPORT_SYMBOL(uuid_null);
  28
  29const u8 guid_index[16] = {3,2,1,0,5,4,7,6,8,9,10,11,12,13,14,15};
  30const u8 uuid_index[16] = {0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15};
  31
  32/**
  33 * generate_random_uuid - generate a random UUID
  34 * @uuid: where to put the generated UUID
  35 *
  36 * Random UUID interface
  37 *
  38 * Used to create a Boot ID or a filesystem UUID/GUID, but can be
  39 * useful for other kernel drivers.
  40 */
  41void generate_random_uuid(unsigned char uuid[16])
  42{
  43        get_random_bytes(uuid, 16);
  44        /* Set UUID version to 4 --- truly random generation */
  45        uuid[6] = (uuid[6] & 0x0F) | 0x40;
  46        /* Set the UUID variant to DCE */
  47        uuid[8] = (uuid[8] & 0x3F) | 0x80;
  48}
  49EXPORT_SYMBOL(generate_random_uuid);
  50
  51static void __uuid_gen_common(__u8 b[16])
  52{
  53        prandom_bytes(b, 16);
  54        /* reversion 0b10 */
  55        b[8] = (b[8] & 0x3F) | 0x80;
  56}
  57
  58void guid_gen(guid_t *lu)
  59{
  60        __uuid_gen_common(lu->b);
  61        /* version 4 : random generation */
  62        lu->b[7] = (lu->b[7] & 0x0F) | 0x40;
  63}
  64EXPORT_SYMBOL_GPL(guid_gen);
  65
  66void uuid_gen(uuid_t *bu)
  67{
  68        __uuid_gen_common(bu->b);
  69        /* version 4 : random generation */
  70        bu->b[6] = (bu->b[6] & 0x0F) | 0x40;
  71}
  72EXPORT_SYMBOL_GPL(uuid_gen);
  73
  74/**
  75 * uuid_is_valid - checks if a UUID string is valid
  76 * @uuid:       UUID string to check
  77 *
  78 * Description:
  79 * It checks if the UUID string is following the format:
  80 *      xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx
  81 *
  82 * where x is a hex digit.
  83 *
  84 * Return: true if input is valid UUID string.
  85 */
  86bool uuid_is_valid(const char *uuid)
  87{
  88        unsigned int i;
  89
  90        for (i = 0; i < UUID_STRING_LEN; i++) {
  91                if (i == 8 || i == 13 || i == 18 || i == 23) {
  92                        if (uuid[i] != '-')
  93                                return false;
  94                } else if (!isxdigit(uuid[i])) {
  95                        return false;
  96                }
  97        }
  98
  99        return true;
 100}
 101EXPORT_SYMBOL(uuid_is_valid);
 102
 103static int __uuid_parse(const char *uuid, __u8 b[16], const u8 ei[16])
 104{
 105        static const u8 si[16] = {0,2,4,6,9,11,14,16,19,21,24,26,28,30,32,34};
 106        unsigned int i;
 107
 108        if (!uuid_is_valid(uuid))
 109                return -EINVAL;
 110
 111        for (i = 0; i < 16; i++) {
 112                int hi = hex_to_bin(uuid[si[i] + 0]);
 113                int lo = hex_to_bin(uuid[si[i] + 1]);
 114
 115                b[ei[i]] = (hi << 4) | lo;
 116        }
 117
 118        return 0;
 119}
 120
 121int guid_parse(const char *uuid, guid_t *u)
 122{
 123        return __uuid_parse(uuid, u->b, guid_index);
 124}
 125EXPORT_SYMBOL(guid_parse);
 126
 127int uuid_parse(const char *uuid, uuid_t *u)
 128{
 129        return __uuid_parse(uuid, u->b, uuid_index);
 130}
 131EXPORT_SYMBOL(uuid_parse);
 132