Re: [PATCH v2] util/qemu-option: Document the get_opt_value() function

[Thomas Huth <thuth@redhat.com>]

On 07/07/2020 07.35, Markus Armbruster wrote:
> Richard Henderson <richard.henderson@linaro.org> writes:
> 
>> On 6/29/20 12:08 AM, Philippe Mathieu-Daudé wrote:
>>> Coverity noticed commit 950c4e6c94 introduced a dereference before
>>> null check in get_opt_value (CID1391003):
>>>
>>>   In get_opt_value: All paths that lead to this null pointer
>>>   comparison already dereference the pointer earlier (CWE-476)
>>>
>>> We fixed this in commit 6e3ad3f0e31, but relaxed the check in commit
>>> 0c2f6e7ee99 because "No callers of get_opt_value() pass in a NULL
>>> for the 'value' parameter".
>>>
>>> Since this function is publicly exposed, it risks new users to do
>>> the same error again. Avoid that documenting the 'value' argument
>>> must not be NULL.
>>
>> I think we should also add some use of __attribute__((nonnull(...))) to enforce
>> this within the compiler.
>>
>> I recently did this without a qemu/compiler.h QEMU_FOO wrapper within
>> target/arm.  But the nonnull option has optional arguments, so it might be
>> difficult to wrap in macros.
> 
> Do we support building with a compuler that lacks this attribute?

It seems to be available in GCC 4.0 already:

https://gcc.gnu.org/onlinedocs/gcc-4.0.0/gcc/Function-Attributes.html

... so the answer to your question is certainly "no". All supported
compilers should have this attribute.

 Thomas