patch for #1416 xslt_stylesheet parameter only works on first request

[Karim Malhas]

Ah, I didn't see that.

Thank you!



On Thu, Nov 16, 2017 at 01:14:57PM +0300, Ruslan Ermilov wrote:
> Hi,
> 
> On Wed, Nov 15, 2017 at 09:57:28PM +0100, Karim Malhas wrote:
> > Hi all,
> > 
> > I recently discovered a bug [0] concerning the xslt_stylesheet directive as
> > documented here [1].
> > 
> > The root cause of this issue is that the parser of the directive also
> > modifies it instead of just reading it. 
> > 
> > I have created a patch which lets the parser work on a copy of that
> > data, so that changes to it will not affect subsequent requests.
> > 
> > In my opinion this is merely a workaround, the parser probably should
> > not modify the data it parsed from the configuration file, but I didn't
> > feel comfortable to make such a big change.
> > 
> > Since this is my first time working with nginx I am seeking feedback on
> > the approach I used.
> > 
> > 
> > Kind regards,
> > Karim Malhas
> > 
> > 
> > 
> > [0] https://trac.nginx.org/nginx/ticket/1416
> > [1] https://nginx.org/en/docs/http/ngx_http_xslt_module.html#xslt_stylesheet
> 
> My patch has just got a positive review from Maxim Dounin, and
> I'm going to commit it later today.  Here it is, for reference:
> 
> # HG changeset patch
> # User Ruslan Ermilov <ru at nginx.com>
> # Date 1510827158 -10800
> #      Thu Nov 16 13:12:38 2017 +0300
> # Node ID e8062e0dd60c8f594106cf4bee8761429702c8e5
> # Parent  687a9344627a48bc307c942148e07a95fc893382
> Xslt: fixed parameters parsing (ticket #1416).
> 
> If parameters were specified in xslt_stylesheet without variables,
> any request except the first would cause an internal server error.
> 
> diff --git a/src/http/modules/ngx_http_xslt_filter_module.c b/src/http/modules/ngx_http_xslt_filter_module.c
> --- a/src/http/modules/ngx_http_xslt_filter_module.c
> +++ b/src/http/modules/ngx_http_xslt_filter_module.c
> @@ -686,8 +686,19 @@ ngx_http_xslt_params(ngx_http_request_t 
>           * specified in xslt_stylesheet directives
>           */
>  
> -        p = string.data;
> -        last = string.data + string.len;
> +        if (param[i].value.lengths) {
> +            p = string.data;
> +
> +        } else {
> +            p = ngx_pnalloc(r->pool, string.len + 1);
> +            if (p == NULL) {
> +                return NGX_ERROR;
> +            }
> +
> +            ngx_memcpy(p, string.data, string.len + 1);
> +        }
> +
> +        last = p + string.len;
>  
>          while (p && *p) {
>  
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> 

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