[PATCH 1 of 2] Cache: fix sending of empty

[Maxim Dounin]

# HG changeset patch
# User Maxim Dounin <mdounin at mdounin.ru>
# Date 1263576719 -10800
# Node ID 065ce686b20763357a61f52f6e4a2e07351fee6b
# Parent  0a974cceb9de159f2daafecf6858518db4688224
Cache: fix sending of empty.

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
@@ -793,6 +793,10 @@ 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));
@@ -805,8 +809,6 @@ 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) {
@@ -816,7 +818,7 @@ 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;