Merge remote-tracking branch 'remotes/kraxel/tags/pull-vga-20170103-1' into staging
[qemu.git] / crypto / random-platform.c
1 /*
2 * QEMU Crypto random number provider
3 *
4 * Copyright (c) 2015-2016 Red Hat, Inc.
5 *
6 * This library is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU Lesser General Public
8 * License as published by the Free Software Foundation; either
9 * version 2 of the License, or (at your option) any later version.
10 *
11 * This library is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * Lesser General Public License for more details.
15 *
16 * You should have received a copy of the GNU Lesser General Public
17 * License along with this library; if not, see <http://www.gnu.org/licenses/>.
18 *
19 */
20
21 #include "qemu/osdep.h"
22
23 #include "crypto/random.h"
24
25 int qcrypto_random_bytes(uint8_t *buf G_GNUC_UNUSED,
26 size_t buflen G_GNUC_UNUSED,
27 Error **errp)
28 {
29 int fd;
30 int ret = -1;
31 int got;
32
33 /* TBD perhaps also add support for BSD getentropy / Linux
34 * getrandom syscalls directly */
35 fd = open("/dev/urandom", O_RDONLY);
36 if (fd == -1 && errno == ENOENT) {
37 fd = open("/dev/random", O_RDONLY);
38 }
39
40 if (fd < 0) {
41 error_setg(errp, "No /dev/urandom or /dev/random found");
42 return -1;
43 }
44
45 while (buflen > 0) {
46 got = read(fd, buf, buflen);
47 if (got < 0) {
48 error_setg_errno(errp, errno,
49 "Unable to read random bytes");
50 goto cleanup;
51 } else if (!got) {
52 error_setg(errp,
53 "Unexpected EOF reading random bytes");
54 goto cleanup;
55 }
56 buflen -= got;
57 buf += got;
58 }
59
60 ret = 0;
61 cleanup:
62 close(fd);
63 return ret;
64 }