1 /* Copyright libuv contributors. All rights reserved.
2 *
3 * Permission is hereby granted, free of charge, to any person obtaining a copy
4 * of this software and associated documentation files (the "Software"), to
5 * deal in the Software without restriction, including without limitation the
6 * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
7 * sell copies of the Software, and to permit persons to whom the Software is
8 * furnished to do so, subject to the following conditions:
9 *
10 * The above copyright notice and this permission notice shall be included in
11 * all copies or substantial portions of the Software.
12 *
13 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
14 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
15 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
16 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
17 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
18 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
19 * IN THE SOFTWARE.
20 */
21
22 #include "uv.h"
23 #include "internal.h"
24
25 #ifdef __linux__
26
27 #define uv__random_getrandom_init() 0
28
29 #else /* !__linux__ */
30
31 #include <stddef.h>
32 #include <dlfcn.h>
33
34 typedef ssize_t (*uv__getrandom_cb)(void *, size_t, unsigned);
35
36 static uv__getrandom_cb uv__getrandom;
37 static uv_once_t once = UV_ONCE_INIT;
38
uv__random_getrandom_init_once(void)39 static void uv__random_getrandom_init_once(void) {
40 uv__getrandom = (uv__getrandom_cb) dlsym(RTLD_DEFAULT, "getrandom");
41 }
42
uv__random_getrandom_init(void)43 static int uv__random_getrandom_init(void) {
44 uv_once(&once, uv__random_getrandom_init_once);
45
46 if (uv__getrandom == NULL)
47 return UV_ENOSYS;
48
49 return 0;
50 }
51
52 #endif /* !__linux__ */
53
uv__random_getrandom(void * buf,size_t buflen)54 int uv__random_getrandom(void* buf, size_t buflen) {
55 ssize_t n;
56 size_t pos;
57 int rc;
58
59 rc = uv__random_getrandom_init();
60 if (rc != 0)
61 return rc;
62
63 for (pos = 0; pos != buflen; pos += n) {
64 do {
65 n = buflen - pos;
66
67 /* Most getrandom() implementations promise that reads <= 256 bytes
68 * will always succeed and won't be interrupted by signals.
69 * It's therefore useful to split it up in smaller reads because
70 * one big read may, in theory, continuously fail with EINTR.
71 */
72 if (n > 256)
73 n = 256;
74
75 n = uv__getrandom((char *) buf + pos, n, 0);
76 } while (n == -1 && errno == EINTR);
77
78 if (n == -1)
79 return UV__ERR(errno);
80
81 if (n == 0)
82 return UV_EIO;
83 }
84
85 return 0;
86 }
87
