[Http-crcsync] crccache ready for some testing I think

[Alex Wulms]

Rusty,

Attached test program crashes on my PC with the latest libcrc. Am I doing 
something wrong? 

Note that it only crashes when the unmatched tail-data in string 'data2' is 
larger then 5 characters (which is my blocksize)

Thanks and brs,
Alex


Ps: here is the uname -a output of my PC, if that might be helpfull:

Linux laptop3 2.6.27.19-3.2-default #1 SMP 2009-02-25 15:40:44 +0100 x86_64 
x86_64 x86_64 GNU/Linux
 


Op maandag 30 maart 2009, schreef Toby Collett:
> I have pulled these changes into the git repo.
>
> Thanks,
> Toby
>
> 2009/3/30 Rusty Russell <rusty at rustcorp.com.au>
>
> > On Monday 30 March 2009 07:31:38 Alex Wulms wrote:
> > > I have also investigated why the cache-server stops finding block
> > > matches after the first difference. I think it is because at this
> > > moment, the
> >
> > cache
> >
> > > server does not read ahead enough in the data-stream. Basically, the
> > > crc_read_block function of Rusty must be fed with as much data as
> >
> > possible,
> >
> > Bug fixed.  Grab latest from ccan, or just apply this patch.
> >
> > Thanks for this: I added tests for feeding 1 byte at a time, and it
> > showed the
> > issue immediately.
> >
> > Cheers,
> > Rusty.
> >
> > === modified file 'ccan/crcsync/crcsync.c'
> > --- ccan/crcsync/crcsync.c      2009-02-17 09:16:33 +0000
> > +++ ccan/crcsync/crcsync.c      2009-03-30 00:07:04 +0000
> > @@ -138,6 +138,7 @@
> >                goto have_match;
> >        }
> >
> > +       /* old is the trailing edge of the checksum window. */
> >        if (buffer_size(ctx) >= ctx->block_size)
> >                old = ctx->buffer + ctx->buffer_start;
> >        else
> > @@ -153,6 +154,7 @@
> >                                                    *old, *p,
> >                                                    ctx->uncrc_tab);
> >                        old++;
> > +                       /* End of stored buffer?  Start on data they gave
> > us. */
> >                        if (old == ctx->buffer + ctx->buffer_end)
> >                                old = buf;
> >                } else {
> > @@ -167,11 +169,6 @@
> >                p++;
> >        }
> >
> > -       /* Make sure we have a copy of the last block_size bytes.
> > -        * First, copy down the old data.  */
> > -       if (buffer_size(ctx)) {
> > -       }
> > -
> >        if (crcmatch >= 0) {
> >                /* We have a match! */
> >                if (ctx->literal_bytes > ctx->block_size) {
> > @@ -187,12 +184,15 @@
> >                        assert(ctx->literal_bytes == 0);
> >                        ctx->have_match = -1;
> >                        ctx->running_crc = 0;
> > +                       /* Nothing more in the buffer. */
> > +                       ctx->buffer_start = ctx->buffer_end = 0;
> >                }
> >        } else {
> >                /* Output literal if it's more than 1 block ago. */
> >                if (ctx->literal_bytes > ctx->block_size) {
> >                        *result = ctx->literal_bytes - ctx->block_size;
> > -                       ctx->literal_bytes = ctx->block_size;
> > +                       ctx->literal_bytes -= *result;
> > +                       ctx->buffer_start += *result;
> >                } else
> >                        *result = 0;
> >
> > @@ -243,29 +243,34 @@
> >  long crc_read_flush(struct crc_context *ctx)
> >  {
> >        long ret;
> > +       size_t final;
> >
> > -       /* In case we ended on a whole block match. */
> > -       if (ctx->have_match == -1) {
> > -               size_t final;
> > -
> > -               final = final_block_match(ctx);
> > -               if (!final) {
> > -                       /* This is how many bytes we're about to consume.
> > */
> > -                       ret = buffer_size(ctx);
> > -                       ctx->buffer_start += ret;
> > -                       ctx->literal_bytes -= ret;
> > -
> > -                       return ret;
> > -               }
> > -               ctx->buffer_start += final;
> > -               ctx->literal_bytes -= final;
> > -               ctx->have_match = ctx->num_crcs-1;
> > -       }
> > -
> > -       /* It might be a partial block match, so no assert */
> > -       ctx->literal_bytes = 0;
> > -       ret = -ctx->have_match-1;
> > -       ctx->have_match = -1;
> > +       /* We might have ended right on a matched block. */
> > +       if (ctx->have_match != -1) {
> > +               ctx->literal_bytes -= ctx->block_size;
> > +               assert(ctx->literal_bytes == 0);
> > +               ret = -ctx->have_match-1;
> > +               ctx->have_match = -1;
> > +               ctx->running_crc = 0;
> > +               /* Nothing more in the buffer. */
> > +               ctx->buffer_start = ctx->buffer_end;
> > +               return ret;
> > +       }
> > +
> > +       /* Look for truncated final block. */
> > +       final = final_block_match(ctx);
> > +       if (!final) {
> > +               /* Nope?  Just a literal. */
> > +               ret = buffer_size(ctx);
> > +               ctx->buffer_start += ret;
> > +               ctx->literal_bytes -= ret;
> > +               return ret;
> > +       }
> > +
> > +       /* We matched (some of) what's left. */
> > +       ret = -(ctx->num_crcs-1)-1;
> > +       ctx->buffer_start += final;
> > +       ctx->literal_bytes -= final;
> >        return ret;
> >  }


-------------- next part --------------
A non-text attachment was scrubbed...
Name: test.c
Type: text/x-csrc
Size: 1770 bytes
Desc: not available
Url : http://lists.laptop.org/pipermail/http-crcsync/attachments/20090330/f2e47378/attachment.c