Re: [Qemu-devel] [PATCH v7 13/35] hostmem-file: use whole file size if possible

[Xiao Guangrong]

On 11/03/2015 01:09 AM, Vladimir Sementsov-Ogievskiy wrote:
> On 02.11.2015 12:13, Xiao Guangrong wrote:
> > Use the whole file size if @size is not specified which is useful
> > if we want to directly pass a file to guest
> >
> > Signed-off-by: Xiao Guangrong <address@hidden>
> > ---
> >   backends/hostmem-file.c | 22 ++++++++++++++++++----
> >   1 file changed, 18 insertions(+), 4 deletions(-)
> >
> > diff --git a/backends/hostmem-file.c b/backends/hostmem-file.c
> > index 9097a57..ea355c1 100644
> > --- a/backends/hostmem-file.c
> > +++ b/backends/hostmem-file.c
> > @@ -38,15 +38,29 @@ file_backend_memory_alloc(HostMemoryBackend *backend, Error 
> > **errp)
> >   {
> >       HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(backend);
> > -    if (!backend->size) {
> > -        error_setg(errp, "can't create backend with size 0");
> > -        return;
> > -    }
> >       if (!fb->mem_path) {
> >           error_setg(errp, "mem-path property not set");
> >           return;
> >       }
> > +    if (!backend->size) {
> > +        Error *local_err = NULL;
> > +
> > +        /*
> > +         * use the whole file size if @size is not specified.
> > +         */
> > +        backend->size = qemu_file_getlength(fb->mem_path, &local_err);
> > +        if (local_err) {
> > +            error_propagate(errp, local_err);
> > +            return;
> > +        }
> > +    }
> > +
> > +    if (!backend->size) {
> > +        error_setg(errp, "can't create backend on the file whose size is 0");
> > +        return;
> > +    }
> > +
> >       backend->force_prealloc = mem_prealloc;
> >       memory_region_init_ram_from_file(&backend->mr, OBJECT(backend),
> >                                    object_get_canonical_path(OBJECT(backend)),
>
> why not just

It look like it is a common style used in whole QEMU code.

> +    if (!backend->size) {
> +        /*
> +         * use the whole file size if @size is not specified.
> +         */
> +        backend->size = qemu_file_getlength(fb->mem_path, errp);
> +        if (*errp) {
> +            return;
> +        }
> +    }

But i think your way is better. :)

> what the purpose of propagating?