Re: [PATCH 04/16] qemu-file: Don't call qemu_fflush() for read only files

[Richard Henderson]

On 5/30/23 10:06, Juan Quintela wrote:
> Richard Henderson <richard.henderson@linaro.org> wrote:
> > On 5/30/23 05:28, Juan Quintela wrote:
> > > This was the only caller for read only files.  So change the test for
> > > an assert in qemu_fflush().
> >
> >
> > Not a fan, as fflush(stdin) is well-defined.
>
> I guess you mean this:
>
>         For input streams associated with seekable files (e.g., disk files, but
>         not pipes or terminals), fflush() discards any buffered data  that  has
>         been fetched from the underlying file, but has not been consumed by the
>         application.

Yes, in that, importantly, it does not assert.

> Two things:
> - Current code just do nothing for imput streams
> - We only call it from qemu_fclose()

Pardon?  There are nearly 30 calls to qemu_fflush.

> - If we drop anything from the input stream, migration get broken.

I'm not talking about dropping anything.  Obviously QEMUFile works different from stdio, 
and therefore resetting the file state to that of the unbuffered data is not relevant.



r~