Fix the use of the default 'flush' provider.

Improve documentation for the "flusher" parameter.
Remove useless empty lines.

See http://mail-archives.apache.org/mod_mbox/httpd-dev/200812.mbox/%3C494226C0.4050407@force-elite.com%3E for some more explanation.
A python script is given there to test.
I had to tweak it to have it work
(use:
        fd, payload = passfd.recvfd(conn.fileno())
instead of:
        fd = passfd.recvfd(conn.fileno())
)


This is a r1058621 regression, where somehow "char *flusher" has been turned into a "char flusher[]". So it is been broken since the beginning of 2.4.x

After this change (i.e. r1058621), 'flusher' is no more a pointer (NULL'ed when the structure it belongs to is created) but the address of an array within a structure. It can not be NULL anymore.
So, we now have to look at the content of the array itself to see if it has been initialized or if we have to use the default value instead.

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1717063 13f79535-47bb-0310-9956-ffa450edef68

CHANGES

@@ -1,6 +1,12 @@
                                                          -*- coding: utf-8 -*-
 Changes with Apache 2.5.0
 
+  *) mod_proxy_fdpass: Fix AH01153 error when using the default configuration.
+     In earlier version of httpd, you can explicitelly set the 'flusher' parameter
+     to 'flush' as a workaround. (i.e. flusher=flush)
+     Add documentation for the 'flusher' parameter when defining a proxy worker.
+     [Christophe Jaillet]
+
   *) mod_ssl: For the "SSLStaplingReturnResponderErrors off" case, make sure
      to only staple responses with certificate status "good". [Kaspar Brand]
 

docs/manual/mod/mod_proxy.xml

@@ -1178,6 +1178,11 @@ ProxyPass "/example" "http://backend.example.com" max=20 ttl=120 retry=300
         connection will not be used again; it will be closed at some
         later time.
     </td></tr>
+    <tr><td>flusher</td>
+        <td>flush</td>
+        <td><p>Name of the provider used by <module>mod_proxy_fdpass</module>.
+        See the documentation of this module for more details.</p>
+    </td></tr>
 
     </table>
 

docs/manual/mod/mod_proxy_fdpass.xml

@@ -42,9 +42,14 @@
 
     <p>The module has a <code>proxy_fdpass_flusher</code> provider interface,
     which allows another module to optionally send the response headers, or even
-    the start of the response body.  The default flush provider disables keep-alive,
-    and sends the response headers, letting the external process just send a
-    response body.</p>
+    the start of the response body.  The default <code>flush</code> provider
+    disables keep-alive, and sends the response headers, letting the external
+    process just send a response body.
+    </p>
+    
+    <p>In order to use another provider, you have to set the <code>flusher</code>
+    parameter in the <directive module="mod_proxy">ProxyPass</directive> directive.
+    </p>
 
     <p>At this time the only data passed to the external process is the client
     socket. To receive a client socket, call recvfrom with an allocated

modules/proxy/mod_proxy_fdpass.c

@@ -57,7 +57,6 @@ static apr_status_t get_socket_from_path(apr_pool_t *p,
     *out_sock = NULL;
 
     rv = apr_socket_create(&s, AF_UNIX, SOCK_STREAM, 0, p);
-
     if (rv != APR_SUCCESS) {
         return rv;
     }
@@ -72,7 +71,6 @@ static apr_status_t get_socket_from_path(apr_pool_t *p,
     return APR_SUCCESS;
 }
 
-
 static apr_status_t send_socket(apr_pool_t *p,
                                 apr_socket_t *s,
                                 apr_socket_t *outbound)
@@ -119,7 +117,6 @@ static apr_status_t send_socket(apr_pool_t *p,
         return errno;
     }
 
-
     return APR_SUCCESS;
 }
 
@@ -149,7 +146,7 @@ static int proxy_fdpass_handler(request_rec *r, proxy_worker *worker,
 
     {
         int status;
-        const char *flush_method = worker->s->flusher ? worker->s->flusher : "flush";
+        const char *flush_method = *worker->s->flusher ? worker->s->flusher : "flush";
 
         proxy_fdpass_flush *flush = ap_lookup_provider(PROXY_FDPASS_FLUSHER,
                                                        flush_method, "0");
@@ -191,7 +188,6 @@ static int proxy_fdpass_handler(request_rec *r, proxy_worker *worker,
         ap_set_core_module_config(r->connection->conn_config, dummy);
     }
 
-
     return OK;
 }