[PATCH 1 of 3] Added support for trailers in HTTP responses

[Piotr Sikora]

Hey Maxim,

> I would prefer to preserve the typical code path (when there are no
> trailers) without an extra allocation.  It looks like it would be
> as trivail as:
>
> @@ -273,14 +273,18 @@ ngx_http_chunked_create_trailers(ngx_htt
>      b->memory = 1;
>      b->last_buf = 1;
>
> +    if (len == sizeof(CRLF "0" CRLF CRLF) - 1) {
> +        b->pos = (u_char *) CRLF "0" CRLF CRLF;
> +        b->last = b->pos + sizeof(CRLF "0" CRLF CRLF) - 1;
> +        return cl;
> +    }

Sounds good, but the if statement reads a bit weird.

What about this instead, even though it might be a bit more expensive?

@@ -236,7 +236,7 @@ ngx_http_chunked_create_trailers(ngx_http_request_t *r,
     ngx_list_part_t  *part;
     ngx_table_elt_t  *header;

-    len = sizeof(CRLF "0" CRLF CRLF) - 1;
+    len = 0;

     part = &r->headers_out.trailers.part;
     header = part->elts;
@@ -273,12 +273,14 @@ ngx_http_chunked_create_trailers(ngx_http_request_t *r,
     b->memory = 1;
     b->last_buf = 1;

-    if (len == sizeof(CRLF "0" CRLF CRLF) - 1) {
+    if (len == 0) {
         b->pos = (u_char *) CRLF "0" CRLF CRLF;
         b->last = b->pos + sizeof(CRLF "0" CRLF CRLF) - 1;
         return cl;
     }

+    len += sizeof(CRLF "0" CRLF CRLF) - 1;
+
     b->pos = ngx_palloc(r->pool, len);
     if (b->pos == NULL) {
         return NULL;

Best regards,
Piotr Sikora