From: "Daniel P. Berrange" <berrange(a)redhat.com&gt; The current virRandomBits() API is only usable if the caller wants a random number in the range [0, (n-1)] where n is a power of two. This adds a virRandom() API which generates a double in the range [0.0,1.0] with 48 bits of entropy. It then also adds a virRandomInt(uint32_t max) API which generates an unsigned in the range [0,@max] Signed-off-by: Daniel P. Berrange <berrange(a)redhat.com&gt; --- src/libvirt_private.syms | 2 ++ src/util/virrandom.c | 32 ++++++++++++++++++++++++++++++++ src/util/virrandom.h | 2 ++ 3 files changed, 36 insertions(+) diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms index 018d3a9..1905d6f 100644 --- a/src/libvirt_private.syms +++ b/src/libvirt_private.syms @@ -1641,8 +1641,10 @@ virPidFileDeletePath; # virrandom.h +virRandom; virRandomBits; virRandomGenerateWWN; +virRandomInt; # virsocketaddr.h diff --git a/src/util/virrandom.c b/src/util/virrandom.c index 50bed46..2092afc 100644 --- a/src/util/virrandom.c +++ b/src/util/virrandom.c @@ -23,6 +23,7 @@ #include <stdlib.h> #include <inttypes.h> +#include <math.h> #include "virrandom.h" #include "threads.h" @@ -108,6 +109,37 @@ uint64_t virRandomBits(int nbits) return ret; } + +/** + * virRandom: + * + * Generate an evenly distributed random number between [0.0,1.0] + * + * Return: a random number with 48 bits of entropy + */ +double virRandom(void) +{ + uint64_t val = virRandomBits(48); + + return ldexp(val, -48); +} + + +/** + * virRandomInt32: + * @max: upper limit + * + * Generate an evenly distributed random integer between [0,@max] + * + * Return: a random number between [0,@max] + */ +uint32_t virRandomInt(uint32_t max) +{ + double val = virRandom(); + return val * max; +} + + #define QUMRANET_OUI "001a4a" #define VMWARE_OUI "000569" #define MICROSOFT_OUI "0050f2" diff --git a/src/util/virrandom.h b/src/util/virrandom.h index 29a055d..bd34c94 100644 --- a/src/util/virrandom.h +++ b/src/util/virrandom.h @@ -25,6 +25,8 @@ # include "internal.h" uint64_t virRandomBits(int nbits); +double virRandom(void); +uint32_t virRandomInt(uint32_t max); int virRandomGenerateWWN(char **wwn, const char *virt_type); #endif /* __VIR_RANDOM_H__ */ -- 1.7.11.2