event-rule: introduce event-rule kprobe
[lttng-tools.git] / src / common / uuid.c
1 /*
2 * Copyright (C) 2018 Jérémie Galarneau <jeremie.galarneau@efficios.com>
3 * Copyright (C) 2019 Michael Jeanson <mjeanson@efficios.com>
4 *
5 * SPDX-License-Identifier: LGPL-2.1-only
6 *
7 */
8
9 #include <common/compat/string.h>
10 #include <stddef.h>
11 #include <stdint.h>
12 #include <stdio.h>
13 #include <stdlib.h>
14 #include <string.h>
15 #include <time.h>
16
17 #include "uuid.h"
18
19 static const lttng_uuid nil_uuid;
20 static bool lttng_uuid_is_init;
21
22 void lttng_uuid_to_str(const lttng_uuid uuid, char *uuid_str)
23 {
24 sprintf(uuid_str, LTTNG_UUID_FMT, LTTNG_UUID_FMT_VALUES(uuid));
25 }
26
27 int lttng_uuid_from_str(const char *str_in, lttng_uuid uuid_out)
28 {
29 int ret = 0;
30 lttng_uuid uuid_scan;
31
32 if ((str_in == NULL) || (uuid_out == NULL)) {
33 ret = -1;
34 goto end;
35 }
36
37 if (lttng_strnlen(str_in, LTTNG_UUID_STR_LEN) != LTTNG_UUID_STR_LEN - 1) {
38 ret = -1;
39 goto end;
40 }
41
42 /* Scan to a temporary location in case of a partial match. */
43 if (sscanf(str_in, LTTNG_UUID_FMT, LTTNG_UUID_SCAN_VALUES(uuid_scan)) !=
44 LTTNG_UUID_LEN) {
45 ret = -1;
46 }
47
48 lttng_uuid_copy(uuid_out, uuid_scan);
49 end:
50 return ret;
51 }
52
53 bool lttng_uuid_is_equal(const lttng_uuid a, const lttng_uuid b)
54 {
55 return memcmp(a, b, LTTNG_UUID_LEN) == 0;
56 }
57
58 bool lttng_uuid_is_nil(const lttng_uuid uuid)
59 {
60 return memcmp(nil_uuid, uuid, sizeof(lttng_uuid)) == 0;
61 }
62
63 void lttng_uuid_copy(lttng_uuid dst, const lttng_uuid src)
64 {
65 memcpy(dst, src, LTTNG_UUID_LEN);
66 }
67
68 /*
69 * Generate a random UUID according to RFC4122, section 4.4.
70 */
71 int lttng_uuid_generate(lttng_uuid uuid_out)
72 {
73 int i, ret = 0;
74
75 if (uuid_out == NULL) {
76 ret = -1;
77 goto end;
78 }
79
80 if (!lttng_uuid_is_init) {
81 /*
82 * We don't need cryptographic quality randomness to
83 * generate UUIDs, seed rand with the epoch.
84 */
85 const time_t epoch = time(NULL);
86
87 if (epoch == (time_t) -1) {
88 ret = -1;
89 goto end;
90 }
91 srand(epoch);
92
93 lttng_uuid_is_init = true;
94 }
95
96 /*
97 * Generate 16 bytes of random bits.
98 */
99 for (i = 0; i < LTTNG_UUID_LEN; i++) {
100 uuid_out[i] = (uint8_t) rand();
101 }
102
103 /*
104 * Set the two most significant bits (bits 6 and 7) of the
105 * clock_seq_hi_and_reserved to zero and one, respectively.
106 */
107 uuid_out[8] &= ~(1 << 6);
108 uuid_out[8] |= (1 << 7);
109
110 /*
111 * Set the four most significant bits (bits 12 through 15) of the
112 * time_hi_and_version field to the 4-bit version number from
113 * Section 4.1.3.
114 */
115 uuid_out[6] &= 0x0f;
116 uuid_out[6] |= (LTTNG_UUID_VER << 4);
117
118 end:
119 return ret;
120 }
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