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7fd8e49ef1
This macro checks whether given number is an integer power of two. At the same time, I've identified two places where we check for pow2 and I'm replacing them with the macro. Signed-off-by: Michal Privoznik <mprivozn@redhat.com> Reviewed-by: Peter Krempa <pkrempa@redhat.com> Reviewed-by: Daniel Henrique Barboza <danielhb413@gmail.com> Tested-by: Daniel Henrique Barboza <danielhb413@gmail.com> Tested-by: Han Han <hhan@redhat.com>
164 lines
3.8 KiB
C
164 lines
3.8 KiB
C
/*
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* Copyright (C) 2012-2016 Red Hat, Inc.
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library. If not, see
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* <http://www.gnu.org/licenses/>.
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*/
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#include <config.h>
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#include <inttypes.h>
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#include <math.h>
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#include <time.h>
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#include <fcntl.h>
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#include <sys/stat.h>
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#include <sys/types.h>
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#include <gnutls/gnutls.h>
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#include <gnutls/crypto.h>
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#include "virrandom.h"
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#include "virthread.h"
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#include "virerror.h"
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#include "virfile.h"
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#include "virlog.h"
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#include "virstring.h"
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#define VIR_FROM_THIS VIR_FROM_NONE
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VIR_LOG_INIT("util.random");
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/**
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* virRandomBits:
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* @nbits: Number of bits of randomness required
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*
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* Generate an evenly distributed random number between [0,2^nbits), where
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* @nbits must be in the range (0,64].
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*
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* Return: a random number with @nbits entropy
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*/
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uint64_t virRandomBits(int nbits)
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{
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uint64_t ret = 0;
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if (virRandomBytes((unsigned char *) &ret, sizeof(ret)) < 0) {
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/* You're already hosed, so this particular non-random value
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* isn't any worse. */
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return 0;
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}
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if (nbits < 64)
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ret &= (1ULL << nbits) - 1;
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return ret;
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}
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/**
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* virRandom:
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*
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* Generate an evenly distributed random number between [0.0,1.0)
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*
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* Return: a random number with 48 bits of entropy
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*/
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double virRandom(void)
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{
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uint64_t val = virRandomBits(48);
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return ldexp(val, -48);
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}
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/**
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* virRandomInt:
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* @max: upper limit
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*
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* Generate an evenly distributed random integer between [0, @max)
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*
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* Return: a random number between [0,@max)
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*/
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uint32_t virRandomInt(uint32_t max)
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{
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if (VIR_IS_POW2(max))
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return virRandomBits(__builtin_ffs(max) - 1);
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return virRandom() * max;
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}
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/**
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* virRandomBytes
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* @buf: Pointer to location to store bytes
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* @buflen: Number of bytes to store
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*
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* Generate a stream of random bytes using gnutls_rnd()
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* into @buf of size @buflen
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*
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* Returns 0 on success or -1 (with error reported)
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*/
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int
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virRandomBytes(unsigned char *buf,
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size_t buflen)
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{
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int rv;
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if ((rv = gnutls_rnd(GNUTLS_RND_RANDOM, buf, buflen)) < 0) {
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virReportError(VIR_ERR_INTERNAL_ERROR,
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_("failed to generate byte stream: %s"),
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gnutls_strerror(rv));
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return -1;
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}
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return 0;
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}
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#define QUMRANET_OUI "001a4a"
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#define VMWARE_OUI "000569"
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#define MICROSOFT_OUI "0050f2"
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#define XEN_OUI "00163e"
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int
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virRandomGenerateWWN(char **wwn,
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const char *virt_type)
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{
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const char *oui = NULL;
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if (!virt_type) {
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virReportError(VIR_ERR_INVALID_ARG, "%s",
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_("argument virt_type must not be NULL"));
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return -1;
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}
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if (STREQ(virt_type, "QEMU")) {
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oui = QUMRANET_OUI;
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} else if (STREQ(virt_type, "Xen") ||
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STREQ(virt_type, "xenlight")) {
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oui = XEN_OUI;
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} else if (STREQ(virt_type, "ESX") ||
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STREQ(virt_type, "VMWARE")) {
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oui = VMWARE_OUI;
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} else if (STREQ(virt_type, "HYPER-V")) {
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oui = MICROSOFT_OUI;
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} else {
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virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
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_("Unsupported virt type"));
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return -1;
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}
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*wwn = g_strdup_printf("5" "%s%09llx", oui,
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(unsigned long long)virRandomBits(36));
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return 0;
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}
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