Messages in this thread | | | Subject | Re: [RFC][PATCH] A generic boolean (version 6) | From | Nicholas Miell <> | Date | Wed, 26 Jul 2006 22:27:27 -0700 |
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On Thu, 2006-07-27 at 04:48 +0200, Arnd Bergmann wrote: > On Wednesday 26 July 2006 22:28, ricknu-0@student.ltu.se wrote: > > Have not found any (real) reason letting the cpp know about false/true. As I > > said in the last version, the only reason seem to be for the userspace. Well, as > > there is no program of my knowlage that needs it, they were removed. > > > If we don't expect this to show up in the ABI (which I hope is true), then > the definition should probably be inside of #ifdef __KERNEL__. Right > now, it's inside of (!__KERNEL_STRICT_NAMES), which is not exactly the > same. >
If _Bool does end up in the user-kernel ABI, be advised that validating them will be tricky ("b == true || b == false" or "!!b" won't work), and the compiler could in theory generate code which tests truthfulness by comparing to 1 in one place and non-zero in another.
My brief IRC conversation with gcc people regarding validating untrusted _Bool resulted in the instruction to never store a value in a _Bool until after it has been validated.
-- Nicholas Miell <nmiell@comcast.net>
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