the-tree/lib/uuid.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /*
0003  * Unified UUID/GUID definition
0004  *
0005  * Copyright (C) 2009, 2016 Intel Corp.
0006  *  Huang Ying <ying.huang@intel.com>
0007  */
0008
0009 #include <linux/kernel.h>
0010 #include <linux/ctype.h>
0011 #include <linux/errno.h>
0012 #include <linux/export.h>
0013 #include <linux/uuid.h>
0014 #include <linux/random.h>
0015
0016 const guid_t guid_null;
0017 EXPORT_SYMBOL(guid_null);
0018 const uuid_t uuid_null;
0019 EXPORT_SYMBOL(uuid_null);
0020
0021 const u8 guid_index[16] = {3,2,1,0,5,4,7,6,8,9,10,11,12,13,14,15};
0022 const u8 uuid_index[16] = {0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15};
0023
0024 /**
0025  * generate_random_uuid - generate a random UUID
0026  * @uuid: where to put the generated UUID
0027  *
0028  * Random UUID interface
0029  *
0030  * Used to create a Boot ID or a filesystem UUID/GUID, but can be
0031  * useful for other kernel drivers.
0032  */
0033 void generate_random_uuid(unsigned char uuid[16])
0034 {
0035     get_random_bytes(uuid, 16);
0036     /* Set UUID version to 4 --- truly random generation */
0037     uuid[6] = (uuid[6] & 0x0F) | 0x40;
0038     /* Set the UUID variant to DCE */
0039     uuid[8] = (uuid[8] & 0x3F) | 0x80;
0040 }
0041 EXPORT_SYMBOL(generate_random_uuid);
0042
0043 void generate_random_guid(unsigned char guid[16])
0044 {
0045     get_random_bytes(guid, 16);
0046     /* Set GUID version to 4 --- truly random generation */
0047     guid[7] = (guid[7] & 0x0F) | 0x40;
0048     /* Set the GUID variant to DCE */
0049     guid[8] = (guid[8] & 0x3F) | 0x80;
0050 }
0051 EXPORT_SYMBOL(generate_random_guid);
0052
0053 static void __uuid_gen_common(__u8 b[16])
0054 {
0055     prandom_bytes(b, 16);
0056     /* reversion 0b10 */
0057     b[8] = (b[8] & 0x3F) | 0x80;
0058 }
0059
0060 void guid_gen(guid_t *lu)
0061 {
0062     __uuid_gen_common(lu->b);
0063     /* version 4 : random generation */
0064     lu->b[7] = (lu->b[7] & 0x0F) | 0x40;
0065 }
0066 EXPORT_SYMBOL_GPL(guid_gen);
0067
0068 void uuid_gen(uuid_t *bu)
0069 {
0070     __uuid_gen_common(bu->b);
0071     /* version 4 : random generation */
0072     bu->b[6] = (bu->b[6] & 0x0F) | 0x40;
0073 }
0074 EXPORT_SYMBOL_GPL(uuid_gen);
0075
0076 /**
0077  * uuid_is_valid - checks if a UUID string is valid
0078  * @uuid:   UUID string to check
0079  *
0080  * Description:
0081  * It checks if the UUID string is following the format:
0082  *  xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx
0083  *
0084  * where x is a hex digit.
0085  *
0086  * Return: true if input is valid UUID string.
0087  */
0088 bool uuid_is_valid(const char *uuid)
0089 {
0090     unsigned int i;
0091
0092     for (i = 0; i < UUID_STRING_LEN; i++) {
0093         if (i == 8 || i == 13 || i == 18 || i == 23) {
0094             if (uuid[i] != '-')
0095                 return false;
0096         } else if (!isxdigit(uuid[i])) {
0097             return false;
0098         }
0099     }
0100
0101     return true;
0102 }
0103 EXPORT_SYMBOL(uuid_is_valid);
0104
0105 static int __uuid_parse(const char *uuid, __u8 b[16], const u8 ei[16])
0106 {
0107     static const u8 si[16] = {0,2,4,6,9,11,14,16,19,21,24,26,28,30,32,34};
0108     unsigned int i;
0109
0110     if (!uuid_is_valid(uuid))
0111         return -EINVAL;
0112
0113     for (i = 0; i < 16; i++) {
0114         int hi = hex_to_bin(uuid[si[i] + 0]);
0115         int lo = hex_to_bin(uuid[si[i] + 1]);
0116
0117         b[ei[i]] = (hi << 4) | lo;
0118     }
0119
0120     return 0;
0121 }
0122
0123 int guid_parse(const char *uuid, guid_t *u)
0124 {
0125     return __uuid_parse(uuid, u->b, guid_index);
0126 }
0127 EXPORT_SYMBOL(guid_parse);
0128
0129 int uuid_parse(const char *uuid, uuid_t *u)
0130 {
0131     return __uuid_parse(uuid, u->b, uuid_index);
0132 }
0133 EXPORT_SYMBOL(uuid_parse);