Re: [PATCH] qemu: qemu_fopen_fd: differentiate between reader and writer user

[Avi Kivity <avi@redhat.com>]

Anthony Liguori wrote:
>>
>> The proposed patch is less that ideal IMO as it introduces
>> limitations on what you can do with a file.  An alternative
>> implementation would add a read/write mode to the buffer, based on
>> the last access type.  When switching from read to write, we drop the
>> buffer, and when switching from write to read, we flush it and then
>> drop it.  This is more complex but results in a cleaner API.
>
> I would think a better solution would introduce two buffers, one for
> read and one for write.  That way, you can have a proper bidirectional
> stream.
>

Complexity goes way up.  Now you need to intercept reads that go to the
write buffer, and vice versa.


-- 
Do not meddle in the internals of kernels, for they are subtle and quick to panic.