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 //
47 class GUIDGenerator {
48 public:
BytesToUInt32(const uint8_t bytes[])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
UInt32ToBytes(uint8_t bytes[],uint32_t n)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
CreateGUID(GUID * guid)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:
InitOnce()74 static void InitOnce() {
75 pthread_once(&once_control, &InitOnceImpl);
76 }
77
InitOnceImpl()78 static void InitOnceImpl() {
79 srandom(time(NULL));
80 }
81
82 static pthread_once_t once_control;
83 };
84
85 pthread_once_t GUIDGenerator::once_control = PTHREAD_ONCE_INIT;
86
CreateGUID(GUID * guid)87 bool CreateGUID(GUID *guid) {
88 return GUIDGenerator::CreateGUID(guid);
89 }
90
91 // Parse guid to string.
GUIDToString(const GUID * guid,char * buf,int buf_len)92 bool 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