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Re: [Qemu-trivial] [Qemu-devel] [trivial for-2.6] util/id: fully allocat

From: Markus Armbruster
Subject: Re: [Qemu-trivial] [Qemu-devel] [trivial for-2.6] util/id: fully allocate names table
Date: Wed, 25 Nov 2015 11:27:24 +0100
User-agent: Gnus/5.13 (Gnus v5.13) Emacs/24.5 (gnu/linux)

Kevin Wolf <address@hidden> writes:

> Am 25.11.2015 um 09:18 hat Markus Armbruster geschrieben:
>> John Snow <address@hidden> writes:
>> > Trivial: this array should be allocated to have ID_MAX entries always.
>> > Otherwise if someone were to forget to expand this table, the assertion
>> > in the id generator won't actually trigger; it will read junk data.
>> You mean this one:
>>     assert(id < ID_MAX);
>> The assertion is crap, because it fails to protect array access
>> id_subsys_str[id].  Here's one that does:
>>     assert(0 <= id && id < ARRAY_SIZE(id_subsys_str));
> Or without the kraxelism id >= 0. However, depending on whether enums
> are signed or unsigned, I seem to remember that this could trigger
> compiler warnings (comparison is always true). And this one should be
> unsigned with gcc because it doesn't include negative values.

Whatever it takes to express the range check in a way the compiler

Since ARRAY_SIZE()'s value is size_t, and size_t is unsigned, the
comparison with 0 can simply be omitted.

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