Re: recent sysctl changes

[Matt Thomas <matt%3am-software.com@localhost>]

On Mar 7, 2014, at 8:32 AM, Andreas Gustafsson <gson%NetBSD.org@localhost> 
wrote:

> Thor Lancelot Simon wrote:
>>> An application could, for example, maintain a single, shared,
>>> malloc'ed buffer that is reused for multiple sysctl() calls and only
>>> resized on ENOMEM returns.  IMO, this is allowed by the API, but with
>>> your change, a read of a CTLTYPE_QUAD variable will return the wrong
>>> result if the buffer happened to be left with a size of 4 by a
>>> previous read of a CTLTYPE_INT variable.
>> 
>> But such a program would already have been buggy -- you can't read 
>> CTLTYPE_QUAD
>> into a buffer of size 4.
> 
> You can *attempt* to read CTLTYPE_QUAD into a buffer of size 4, 
> get ENOMEM, increase the buffer size, and retry.

That's a specious argument.  If you know the type if QUAD, and you
use less than a buffer size of 8, it's a bug (and you're an idiot).

That's like saying I can supply a bogus address, get EFAULT, and try
with a good address.