Subject: Re: [PATCH] gitweb: hack around CGI's list-context param() handling

From: Junio C Hamano <[email-masked]>
Date: Tue, 18 Nov 2014 09:58:26 -0800

Jeff King <[email-masked]> writes:

> As of CGI.pm's 4.08 release, the behavior to call
> CGI::param() in a list context is deprecated (because it can
> be potentially unsafe if called inside a hash constructor).
> This cause gitweb to issue a warning for some of our code,
> which in turn causes the tests to fail.
>
> Our use is in fact _not_ one of the dangerous cases, as we
> are intentionally using a list context. The recommended
> route by 4.08 is to use the new CGI::multi_param() call to
> make it explicit that we know what we are doing.
> However, that function is only available in 4.08, which is
> about a month old; we cannot rely on having it.
>
> One option would be to set $CGI::LIST_CONTEXT_WARN globally,
> which turns off the warning. However, that would eliminate
> the protection these newer releases are trying to provide.
> We want to annotate each site as OK using the new function.
>
> So instead, let's check whether CGI provides the
> multi_param() function, and if not, provide an
> implementation that just wraps param(). That will work on
> both old and new versions of CGI. Sadly, we cannot just
> check defined(\&CGI::multi_param), because CGI uses the
> autoload feature, which claims that all functions are
> defined. Instead, we just do a version check.

The solution does look like the best in the messy situation.  Thanks
for looking into it.

> +if (!defined($CGI::VERSION) || $CGI::VERSION < 4.08) {
> +	eval 'sub CGI::multi_param { CGI::param(@_) }'
> +}
> +
>  our $t0 = [ gettimeofday() ];
>  our $number_of_git_cmds = 0;
>  
> @@ -871,7 +875,7 @@ sub evaluate_query_params {
>  
>  	while (my ($name, $symbol) = each %cgi_param_mapping) {
>  		if ($symbol eq 'opt') {
> -			$input_params{$name} = [ map { decode_utf8($_) } $cgi->param($symbol) ];
> +			$input_params{$name} = [ map { decode_utf8($_) } $cgi->multi_param($symbol) ];
>  		} else {
>  			$input_params{$name} = decode_utf8($cgi->param($symbol));
>  		}