On Mon, Dec 16, 2013 at 2:15 AM, Ruslan Ermilov <ru@nginx.com> wrote:
> On Sun, Dec 15, 2013 at 04:31:08PM -0500, Jeffrey Walton wrote:
>> From Miller's http://www.evanmiller.org/nginx-modules-guide.html, section 5.2:
>>
>> ngx_http_upstream_hash(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
>> {
>> ngx_http_upstream_srv_conf_t *uscf;
>> ngx_http_script_compile_t sc;
>> ngx_str_t *value;
>> ngx_array_t *vars_lengths, *vars_values;
>>
>> value = cf->args->elts;
>>
>> /* the following is necessary to evaluate the argument to "hash"
>> as a $variable */
>> ngx_memzero(&sc, sizeof(ngx_http_script_compile_t));
>>
>> vars_lengths = NULL;
>> vars_values = NULL;
>>
>> sc.cf = cf;
>> sc.source = &value[1];
>> ...
>> }
>>
>> How does one know that value[1] is valid? Shouldn't cf->args->nelts be
>> checked first? Or does ngx_conf_t always have at least two options?
>> Related: why was value[0] not chosen?
>
> value[0] is the directive name, "hash" in this case. It's
> like argv[] in main().
>
> The "hash" directive can be specified in the "upstream" context
> (NGX_HTTP_UPS_CONF) and it takes exactly one argument (NGX_CONF_TAKE1).
> The generic configuration parser code ensures that the argument
> exists.
>
> http://www.evanmiller.org/nginx-modules-guide.html#directives
Ah, thanks. It makes perfect sense.

Jeff

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