[PATCH] [PATCH] debuginfod: Use the debuginfod-size response header

[Mark Wielaard]

Hi Aaron,

On Tue, 2022-01-11 at 22:07 -0500, Aaron Merey via Elfutils-devel
wrote:
> In some cases the content-length header may not be available in order
> to pass to a progressfn.  If content-length isn't available then attempt
> to get the size of the download from the debuginfod-size header instead.
> 
> It should be mentioned that if a compressed file (ex. gzip) is being
> transferred, the actual transfer length will be less than debuginfod-size.
> In this case debuginfod-size is a best-guess upper bound on the size of
> the transfer.

Sorry this patch wasn't reviewed for such a long time. It looks correct
and is also a nice cleanup. Consolidating getting the download size in
one place instead of two (for the progress function and the maxsize
check).

Just a question about this part:

> +          /* If Content-Length is -1, try to get the size from
> +             X-Debuginfod-Size */
> +          if (dl_size == -1 && c->winning_headers != NULL)
> +            {
> +              double xdl;
> +              char *hdr = strstr(c->winning_headers, "x-debuginfod-size");
> +
> +              if (hdr != NULL
> +                  && sscanf(hdr, "x-debuginfod-size: %lf", &xdl) == 1)
> +                dl_size = (xdl >= (double)(LONG_MAX+1UL) ? LONG_MAX : (long)xdl);
> +            }
> +        }

In debuginfod.cxx the header is spelled all uppercase as "X-DEBUGINFOD-
SIZE" which is also what is checked for in the run-debuginfod-response-
headers.sh test. So shouldn't the above also be all uppercase or should
you use strcasestr?

When using sscanf why are you using a double and %lf? Isn't it simpler
to use a long and %ld?

Is there a way to test this easily? When would Content-Length not be
available?

Cheers,

Mark