Re: [PATCH] bootm: improve error message when gzip decompression buffer is too small

[Tom Rini <trini@konsulko.com>]

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On Tue, Apr 29, 2025 at 06:08:50PM +0800, 陳偉銘 wrote:
> Tom Rini <trini@konsulko.com> 於 2025年4月29日 週二 上午1:24寫道：
> >
> > On Mon, Apr 28, 2025 at 02:07:57PM +0800, Aristo Chen wrote:
> >
> > > Currently, when decompressing a gzip-compressed image during bootm, a
> > > generic error such as "inflate() returned -5" is shown when the buffer is
> > > too small. However, it is not immediately clear that this is caused by
> > > CONFIG_SYS_BOOTM_LEN being too small.
> > >
> > > This patch improves error handling by:
> > > - Detecting Z_BUF_ERROR (-5) returned from the inflate() call
> > > - Suggesting the user to increase CONFIG_SYS_BOOTM_LEN when applicable
> > > - Preserving the original return code from zunzip() instead of overwriting
> > >   it with -1
> > >
> > > By providing clearer hints when decompression fails due to insufficient
> > > buffer size, this change helps users diagnose and fix boot failures more
> > > easily.
> > >
> > > Signed-off-by: Aristo Chen <aristo.chen@canonical.com>
> >
> > I like the concept but:
> >
> > > @@ -573,12 +574,26 @@ static int handle_decomp_error(int comp_type, size_t uncomp_size,
> > >                              size_t buf_size, int ret)
> > >  {
> > >       const char *name = genimg_get_comp_name(comp_type);
> > > +     bool likely_buf_too_small = false;
> > >
> > >       /* ENOSYS means unimplemented compression type, don't reset. */
> > >       if (ret == -ENOSYS)
> > >               return BOOTM_ERR_UNIMPLEMENTED;
> > >
> > > +     switch (comp_type) {
> > > +     case IH_COMP_GZIP:
> > > +             if (ret == Z_BUF_ERROR) /* -5 */
> > > +                     likely_buf_too_small = true;
> > > +             break;
> > > +     // Add more if necessary
> > > +     default:
> > > +             break;
> > > +     }
> > > +
> > >       if (uncomp_size >= buf_size)
> > > +             likely_buf_too_small = true;
> > > +
> > > +     if (likely_buf_too_small)
> > >               printf("Image too large: increase CONFIG_SYS_BOOTM_LEN\n");
> > >       else
> > >               printf("%s: uncompress error %d\n", name, ret);
> >
> > This is a lot of code, why not just:
> > if (comp_type == IH_COMP_GZIP && ret == Z_BUF_ERROR)
> >   printf("Image too large: increase CONFIG_SYS_BOOTM_LEN\n");
> >
> Thanks for your suggestion! I am not sure if I get it correctly, do
> you mean that we should remove the original if condition( if
> (uncomp_size >= buf_size) ) that prints the error message?

Ah sorry for being unclear. I just meant we can handle the new print
more directly.

-- 
Tom

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