disabling sleep when shutting down

[Colin Percival]

On 09/22/15 12:13, Jung-uk Kim wrote:
>> I didn't want to pollute init with arch-dependent hacks. Anyway,
>> the attached patch should do what you want (not tested).
> 
> Or a simpler hack with sysctl(3) instead of ioctl(2).

Right, this is more like what I was thinking.  (I can write patches myself
btw -- I was asking for help with figuring out the right solution, not with
the coding itself!)

A couple things I'm not sure about though:
> +	/* Temporarily block any suspend requests. */
> +	len = sizeof(blocked);
> +	block = 1;
> +	if (sysctlbyname("debug.acpi.sleep_blocked", &blocked, &len,
> +	    &block, sizeof(block)) == -1)
> +		blocked = 0;

Wouldn't it make sense to wrap this in "if (Reboot)"?  That way it would block
suspend for poweroff / halt / reboot, but not for dropping to single-user
mode.

> +#if defined(__amd64__) || defined(__i386__)
> +	/* Unblock suspend requests. */
> +	if (!blocked)
> +		sysctlbyname("debug.acpi.sleep_blocked", NULL, NULL,
> +		    &blocked, sizeof(blocked));
> +#endif
> +

And if we restrict the blocking to only happen if (Reboot), is there any point
unblocking suspend when we're about to call reboot(2)?

-- 
Colin Percival
Security Officer Emeritus, FreeBSD | The power to serve
Founder, Tarsnap | www.tarsnap.com | Online backups for the truly paranoid