Re: [Qemu-devel] [trivial for-2.6] util/id: fully allocate names table

[Markus Armbruster <armbru@redhat.com>]

Kevin Wolf <kwolf@redhat.com> writes:

> Am 25.11.2015 um 09:18 hat Markus Armbruster geschrieben:
>> John Snow <jsnow@redhat.com> 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
likes.

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