Re: [PATCH v4 0/7] util: Introduce qemu_get_runtime_dir()

[Akihiko Odaki <akihiko.odaki@daynix.com>]

On 2024/07/16 19:43, Paolo Bonzini wrote:
> On Tue, Jul 16, 2024 at 11:56 AM Daniel P. Berrangé <berrange@redhat.com> wrote:
>>
>> On Tue, Jul 16, 2024 at 11:06:57AM +0300, Michael Tokarev wrote:
>>> 16.07.2024 10:27, Akihiko Odaki wrote:
>>>> qemu_get_runtime_dir() returns a dynamically allocated directory path
>>>> that is appropriate for storing runtime files. It corresponds to "run"
>>>> directory in Unix.
>>>
>>> Since runtime dir is always used with a filename within, how about
>>>
>>>    char *qemu_get_runtime_path(const char *filename)
>>>
>>> which return RUNTIME_DIR/filename instead of just RUNTIME_DIR ?
>>
>> Yeah, I agree, every single caller of the function goes on to call
>> g_build_filename with the result. The helper should just be building
>> the filename itself.
> 
> That would mean using variable arguments and g_build_filename_valist().

We can't prepend an element to va_list. The best thing I came up with is 
a macro as follows:

#define get_runtime_path(first_element, ...) ({ \
   g_autofree char *_s = qemu_get_runtime_dir(); \
   g_build_filename(_s, first_element, ...); \
})

But it makes me wonder if we need such a macro.

Regards,
Akihiko Odaki