[PATCH 24 of 31] Cache: fix sending of empty responses

[Maxim Dounin]

# HG changeset patch
# User Maxim Dounin <mdounin at mdounin.ru>
# Date 1297776703 -10800
# Node ID c0eb70bfa1d7e6cfe3c246a508dba9cdfe2708a2
# Parent  8cce4c8d14c8bf138c401bc90ca1e0c5005161b1
Cache: fix sending of empty responses.

Revert wrong fix for empty responses introduced in 0.8.31 and apply new one,
rewritten to match things done by static module as close as possible.

diff --git a/src/http/ngx_http_file_cache.c b/src/http/ngx_http_file_cache.c
--- a/src/http/ngx_http_file_cache.c
+++ b/src/http/ngx_http_file_cache.c
@@ -866,6 +866,10 @@ ngx_http_cache_send(ngx_http_request_t *
     ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                   "http file cache send: %s", c->file.name.data);
 
+    if (r != r->main && c->length - c->body_start == 0) {
+        return ngx_http_send_header(r);
+    }
+
     /* we need to allocate all before the header would be sent */
 
     b = ngx_pcalloc(r->pool, sizeof(ngx_buf_t));
@@ -878,8 +882,6 @@ ngx_http_cache_send(ngx_http_request_t *
         return NGX_HTTP_INTERNAL_SERVER_ERROR;
     }
 
-    r->header_only = (c->length - c->body_start) == 0;
-
     rc = ngx_http_send_header(r);
 
     if (rc == NGX_ERROR || rc > NGX_OK || r->header_only) {
@@ -889,7 +891,7 @@ ngx_http_cache_send(ngx_http_request_t *
     b->file_pos = c->body_start;
     b->file_last = c->length;
 
-    b->in_file = 1;
+    b->in_file = (c->length - c->body_start) ? 1: 0;
     b->last_buf = (r == r->main) ? 1: 0;
     b->last_in_chain = 1;