[pbs-devel] [RFC pxar 2/20] fix #3174: decoder: factor out skip_bytes from skip_entry

[Christian Ebner]

> On 27.09.2023 13:32 CEST Wolfgang Bumiller <w.bumiller at proxmox.com> wrote:
> 
>  
> On Fri, Sep 22, 2023 at 09:16:03AM +0200, Christian Ebner wrote:
> > Allows to skip bytes independently of the current entries header, as is
> > implemented by skip_entry.
> > 
> > Signed-off-by: Christian Ebner <c.ebner at proxmox.com>
> > ---
> >  src/decoder/mod.rs | 19 ++++++++++++-------
> >  1 file changed, 12 insertions(+), 7 deletions(-)
> > 
> > diff --git a/src/decoder/mod.rs b/src/decoder/mod.rs
> > index d1fb911..2ca263b 100644
> > --- a/src/decoder/mod.rs
> > +++ b/src/decoder/mod.rs
> > @@ -562,20 +562,25 @@ impl<I: SeqRead> DecoderImpl<I> {
> >      // These utilize additional information and hence are not part of the `dyn SeqRead` impl.
> >      //
> >  
> > -    async fn skip_entry(&mut self, offset: u64) -> io::Result<()> {
> > -        let mut len = self.current_header.content_size() - offset;
> > +    async fn skip_bytes(&mut self, len: usize) -> io::Result<()> {
> 
> I think `len` here should be an `u64`, `skip_entry` otherwise gets
> limited to 32 bits on some systems for no reason :-)

Yes, I will change this in the next version of the patch series, thx!

> 
> > +        let mut remaining = len;
> >          let scratch = scratch_buffer();
> > -        while len >= (scratch.len() as u64) {
> > +        while remaining >= scratch.len() {
> >              seq_read_exact(&mut self.input, scratch).await?;
> > -            len -= scratch.len() as u64;
> > +            remaining -= scratch.len();
> >          }
> > -        let len = len as usize;
> > -        if len > 0 {
> > -            seq_read_exact(&mut self.input, &mut scratch[..len]).await?;
> > +        if remaining > 0 {
> > +            seq_read_exact(&mut self.input, &mut scratch[..remaining]).await?;
> >          }
> >          Ok(())
> >      }
> >  
> > +    async fn skip_entry(&mut self, offset: u64) -> io::Result<()> {
> > +        let len =
> > +            usize::try_from(self.current_header.content_size() - offset).map_err(io_err_other)?;
> > +        self.skip_bytes(len).await
> > +    }
> > +
> >      async fn read_entry_as_bytes(&mut self) -> io::Result<Vec<u8>> {
> >          let size = usize::try_from(self.current_header.content_size()).map_err(io_err_other)?;
> >          let data = seq_read_exact_data(&mut self.input, size).await?;
> > -- 
> > 2.39.2