[PATCH vkd3d] vkd3d-shader: Allow a NULL buffer in vkd3d_string_buffer.

[Zebediah Figura]

On 10/4/21 3:32 AM, Giovanni Mascellani wrote:
> Semantically, a NULL buffer is considered equivalent to the empty string.
> The accessor vkd3d_string_buffer_data implements this equivalence.
> 
> The reason for this change is to avoid asserting the result of a memory
> allocation in vkd3d_string_buffer_init, while at the same time keeping
> it always successful.

Well, I guess this is one alternative to 216057. I don't dislike it.

> @@ -855,7 +856,7 @@ struct vkd3d_string_buffer *hlsl_type_to_string(struct hlsl_ctx *ctx, const stru
>   
>               if ((inner_string = hlsl_type_to_string(ctx, t)))
>               {
> -                vkd3d_string_buffer_printf(string, "%s", inner_string->buffer);
> +                vkd3d_string_buffer_printf(string, "%s", vkd3d_string_buffer_data(inner_string));
>                   hlsl_release_string_buffer(ctx, inner_string);
>               }
>   

This means that here, and everywhere else, you can get rid of the NULL 
check.

> diff --git a/libs/vkd3d-shader/vkd3d_shader_main.c b/libs/vkd3d-shader/vkd3d_shader_main.c
> index ef9eaef5..8a2dd0e3 100644
> --- a/libs/vkd3d-shader/vkd3d_shader_main.c
> +++ b/libs/vkd3d-shader/vkd3d_shader_main.c
> @@ -25,11 +25,9 @@ VKD3D_DEBUG_ENV_NAME("VKD3D_SHADER_DEBUG");
>   
>   void vkd3d_string_buffer_init(struct vkd3d_string_buffer *buffer)
>   {
> -    buffer->buffer_size = 16;
> +    buffer->buffer_size = 0;
>       buffer->content_size = 0;
> -    buffer->buffer = vkd3d_malloc(buffer->buffer_size);
> -    assert(buffer->buffer);
> -    memset(buffer->buffer, 0, buffer->buffer_size);
> +    buffer->buffer = NULL;
>   }
>   

I'm assuming this was accidental.

>   void vkd3d_string_buffer_cleanup(struct vkd3d_string_buffer *buffer)
> @@ -37,20 +35,29 @@ void vkd3d_string_buffer_cleanup(struct vkd3d_string_buffer *buffer)
>       vkd3d_free(buffer->buffer);
>   }
>   
> +const char *vkd3d_string_buffer_data(const struct vkd3d_string_buffer *buffer)
> +{
> +    return buffer->buffer ? buffer->buffer : "";
> +}
> +

Should this be defined in vkd3d_shader_private.h as an inline function?