[Patch] Re: Directive "map" not working with regex key and value that like "$1"

[Maxim Dounin]

Hello!

On Sun, Dec 21, 2014 at 11:03:24AM +0800, kindy wrote:

> The root cause there are both. var_values & value_hashs.
> when used with regex key, we should not use var_values,
> because numbered capture are not registered as nginx variable.
> 
> so directive like "~(.+) $1;" will add $1 into var_values by mistake, but
> latter regex will not add this variable..

No.  The root cause is that $1 variables are special and can't be 
handled using the ngx_http_get_variable_index() function.  As 
map{} uses the ngx_http_get_variable_index(), it doesn't 
understand $1..$9 variables.

If you want to access captures in resulting values in a map, 
you can use named captures instead:

    map  $foo         $bar {
         ~(<temp>.*)  $temp;
    }

> ---start of patch---
> 
> --- nginx-1.1.19-orig/src/http/modules/ngx_http_map_module.c 2012-01-18
> 23:07:43.000000000 +0800
> +++ nginx-1.1.19-fixe/src/http/modules/ngx_http_map_module.c 2014-12-20
> 10:42:01.000000000 +0800
> @@ -403,6 +403,10 @@
>          return ngx_conf_parse(cf, &file);
>      }
> 
> +#if (NGX_PCRE)
> +    if (!value[0].len || value[0].data[0] != '~') {
> +#endif
> +
>      if (value[1].data[0] == '$') {
>          name = value[1];
>          name.len--;

This patch is wrong, it will prevent variable expansion in 
resulting values if a source value is specified using a regular 
expression.

[...]

-- 
Maxim Dounin
http://nginx.org/