1// Copyright (c) 2006, Google Inc.
2// All rights reserved.
3//
4// Redistribution and use in source and binary forms, with or without
5// modification, are permitted provided that the following conditions are
6// met:
7//
8//     * Redistributions of source code must retain the above copyright
9// notice, this list of conditions and the following disclaimer.
10//     * Redistributions in binary form must reproduce the above
11// copyright notice, this list of conditions and the following disclaimer
12// in the documentation and/or other materials provided with the
13// distribution.
14//     * Neither the name of Google Inc. nor the names of its
15// contributors may be used to endorse or promote products derived from
16// this software without specific prior written permission.
17//
18// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
19// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
20// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
21// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
22// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
23// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
24// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
25// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
26// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
27// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
28// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29
30#include "common/linux/guid_creator.h"
31
32#include <assert.h>
33#include <pthread.h>
34#include <stdio.h>
35#include <stdlib.h>
36#include <time.h>
37#include <unistd.h>
38
39//
40// GUIDGenerator
41//
42// This class is used to generate random GUID.
43// Currently use random number to generate a GUID since Linux has
44// no native GUID generator. This should be OK since we don't expect
45// crash to happen very offen.
46//
47class GUIDGenerator {
48 public:
49  static uint32_t BytesToUInt32(const uint8_t bytes[]) {
50    return ((uint32_t) bytes[0]
51            | ((uint32_t) bytes[1] << 8)
52            | ((uint32_t) bytes[2] << 16)
53            | ((uint32_t) bytes[3] << 24));
54  }
55
56  static void UInt32ToBytes(uint8_t bytes[], uint32_t n) {
57    bytes[0] = n & 0xff;
58    bytes[1] = (n >> 8) & 0xff;
59    bytes[2] = (n >> 16) & 0xff;
60    bytes[3] = (n >> 24) & 0xff;
61  }
62
63  static bool CreateGUID(GUID *guid) {
64    InitOnce();
65    guid->data1 = random();
66    guid->data2 = (uint16_t)(random());
67    guid->data3 = (uint16_t)(random());
68    UInt32ToBytes(&guid->data4[0], random());
69    UInt32ToBytes(&guid->data4[4], random());
70    return true;
71  }
72
73 private:
74  static void InitOnce() {
75    pthread_once(&once_control, &InitOnceImpl);
76  }
77
78  static void InitOnceImpl() {
79    srandom(time(NULL));
80  }
81
82  static pthread_once_t once_control;
83};
84
85pthread_once_t GUIDGenerator::once_control = PTHREAD_ONCE_INIT;
86
87bool CreateGUID(GUID *guid) {
88  return GUIDGenerator::CreateGUID(guid);
89}
90
91// Parse guid to string.
92bool GUIDToString(const GUID *guid, char *buf, int buf_len) {
93  // Should allow more space the the max length of GUID.
94  assert(buf_len > kGUIDStringLength);
95  int num = snprintf(buf, buf_len, kGUIDFormatString,
96                     guid->data1, guid->data2, guid->data3,
97                     GUIDGenerator::BytesToUInt32(&(guid->data4[0])),
98                     GUIDGenerator::BytesToUInt32(&(guid->data4[4])));
99  if (num != kGUIDStringLength)
100    return false;
101
102  buf[num] = '\0';
103  return true;
104}
105