Re: [Xen-devel] [PATCH 5 of 9] xl: Add function to generate rand

On Tue, 2010-07-27 at 11:13 +0100, Ian Campbell wrote:
> +static void random_uuid(uint8_t *uuid)
> +{
> +    int i;
> +    for (i = 0; i < 16; i++)
> +        uuid[i] = rand();
> +}
> +

Nothing wrong with the patch but draws my attention to the fact that
this method seems far too likely to collide UUID's, for example in xl
invocations started during the same second. Why not use system entropy
pool? eg. scanf contents of /proc/sys/kernel/rand/uuid... I'm aware this
ought to be portable but PRNG can always be a fallback.

Gianni

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[Xen-devel] [PATCH 6 of 9] xl: do not try and auto re-connect console on reboot, (continued) [Xen-devel] [PATCH 6 of 9] xl: do not try and auto re-connect console on reboot, Ian Campbell [Xen-devel] [PATCH 7 of 9] xl: Add function to generate random uuid and use it, Ian Campbell [Xen-devel] [PATCH 8 of 9] xl: Factor out domain death handling into a separate function, Ian Campbell [Xen-devel] [PATCH 9 of 9] xl: support on_{poweroff, reboot, crash} domain configuration options, Ian Campbell [Xen-devel] [PATCH 0 of 9] xl: handle domain shutdown/reboot/crash in a user configurable way, Ian Campbell [Xen-devel] [PATCH 1 of 9] libxl: Add LIBXL_EVENT namespace to enum libxl_event_type, Ian Campbell [Xen-devel] [PATCH 2 of 9] libxl: add shutdown reason to libxl_dominfo, Ian Campbell [Xen-devel] [PATCH 3 of 9] libxl: return libxl_dominfo from libxl_event_get_domain_death_info, Ian Campbell [Xen-devel] [PATCH 4 of 9] libxl: signal caller if domain already destroyed on domain death event, Ian Campbell [Xen-devel] [PATCH 5 of 9] xl: Add function to generate random uuid and use it, Ian Campbell Re: [Xen-devel] [PATCH 5 of 9] xl: Add function to generate random uuid and use it, Gianni Tedesco <= Re: [Xen-devel] [PATCH 5 of 9] xl: Add function to generate random uuid and use it, Ian Jackson Re: [Xen-devel] [PATCH 5 of 9] xl: Add function to generate random uuid and use it, Ian Campbell [Xen-devel] [PATCH 6 of 9] xl: Factor out domain death handling into a separate function, Ian Campbell [Xen-devel] [PATCH 7 of 9] xl: support on_{poweroff, reboot, crash} domain configuration options, Ian Campbell [Xen-devel] [PATCH 8 of 9] libxl: add libxl_domain_preserve, Ian Campbell [Xen-devel] [PATCH 9 of 9] xl: implement "rename-restart" action for shutdown, Ian Campbell

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Re: [Xen-devel] [PATCH 5 of 9] xl: Add function to generate random uuid