[mod_cgi] improve CGI offloading

improve CGI offloading when not streaming request body

If not streaming request body, collect request body into single tempfile
and use fd to tempfile as stdin to CGI (in lieu of input pipe()).
For prior behavior, set the following config option, enabled by default:
  server.feature-flags += ("cgi.tempfile-accum" => "disable")

If there is no request body, open /dev/null instead of creating pipe().

src/mod_cgi.c

@@ -73,6 +73,7 @@ typedef struct {
 	PLUGIN_DATA;
 	plugin_config defaults;
 	plugin_config conf;
+	int tempfile_accum;
 	struct cgi_pid_t *cgi_pid;
 	env_accum env;
 } plugin_data;
@@ -313,6 +314,12 @@ SETDEFAULTS_FUNC(mod_cgi_set_defaults) {
             mod_cgi_merge_config(&p->defaults, cpv);
     }
 
+    p->tempfile_accum =
+      !srv->srvconf.feature_flags
+      || config_plugin_value_tobool(
+          array_get_element_klen(srv->srvconf.feature_flags,
+                                 CONST_STR_LEN("cgi.tempfile-accum")), 1);
+
     return HANDLER_GO_ON;
 }
 
@@ -391,11 +398,13 @@ static void cgi_connection_close(handler_ctx *hctx) {
 }
 
 static handler_t cgi_connection_close_callback(request_st * const r, void *p_d) {
-	plugin_data *p = p_d;
-	handler_ctx *hctx = r->plugin_ctx[p->id];
-	if (hctx) cgi_connection_close(hctx);
-
-	return HANDLER_GO_ON;
+    handler_ctx *hctx = r->plugin_ctx[((plugin_data *)p_d)->id];
+    if (hctx) {
+        chunkqueue_set_tempdirs(&r->reqbody_queue, /* reset sz */
+                                r->reqbody_queue.tempdirs, 0);
+        cgi_connection_close(hctx);
+    }
+    return HANDLER_GO_ON;
 }
 
 
@@ -672,13 +681,49 @@ static int cgi_create_env(request_st * const r, plugin_data * const p, handler_c
 		}
 	}
 
-	if (pipe_cloexec(to_cgi_fds)) {
+	to_cgi_fds[0] = -1;
+  #ifndef __CYGWIN__
+	if (0 == r->reqbody_length) {
+		/* future: might keep fd open in p->devnull for reuse
+		 * and dup() here, or do not close() (later in this func) */
+		to_cgi_fds[0] = fdevent_open_devnull();
+		if (-1 == to_cgi_fds[0]) {
+			log_perror(r->conf.errh, __FILE__, __LINE__, "open /dev/null");
+			return -1;
+		}
+	}
+	else if (!(r->conf.stream_request_body /*(if not streaming request body)*/
+	           & (FDEVENT_STREAM_REQUEST|FDEVENT_STREAM_REQUEST_BUFMIN))) {
+		chunkqueue * const cq = &r->reqbody_queue;
+		chunk * const c = cq->first;
+		if (c && c == cq->last && c->type == FILE_CHUNK && c->file.is_temp) {
+			/* request body in single tempfile if not streaming req body */
+			if (-1 == c->file.fd
+			    && 0 != chunkqueue_open_file_chunk(cq, r->conf.errh))
+				return -1;
+			if (-1 == lseek(c->file.fd, 0, SEEK_SET)) {
+				log_perror(r->conf.errh, __FILE__, __LINE__,
+				  "lseek %s", c->mem->ptr);
+				return -1;
+			}
+			to_cgi_fds[0] = c->file.fd;
+			to_cgi_fds[1] = -1;
+		}
+	}
+  #endif
+
+	if (-1 == to_cgi_fds[0] && pipe_cloexec(to_cgi_fds)) {
 		log_perror(r->conf.errh, __FILE__, __LINE__, "pipe failed");
 		return -1;
 	}
 	if (pipe_cloexec(from_cgi_fds)) {
-		close(to_cgi_fds[0]);
-		close(to_cgi_fds[1]);
+		if (0 == r->reqbody_length) {
+			close(to_cgi_fds[0]);
+		}
+		else if (-1 != to_cgi_fds[1]) {
+			close(to_cgi_fds[0]);
+			close(to_cgi_fds[1]);
+		}
 		log_perror(r->conf.errh, __FILE__, __LINE__, "pipe failed");
 		return -1;
 	}
@@ -756,25 +801,35 @@ static int cgi_create_env(request_st * const r, plugin_data * const p, handler_c
 		if (-1 != dfd) close(dfd);
 		close(from_cgi_fds[0]);
 		close(from_cgi_fds[1]);
-		close(to_cgi_fds[0]);
-		close(to_cgi_fds[1]);
+		if (0 == r->reqbody_length) {
+			close(to_cgi_fds[0]);
+		}
+		else if (-1 != to_cgi_fds[1]) {
+			close(to_cgi_fds[0]);
+			close(to_cgi_fds[1]);
+		}
 		return -1;
 	} else {
 		if (-1 != dfd) close(dfd);
 		close(from_cgi_fds[1]);
-		close(to_cgi_fds[0]);
 
 		hctx->fd = from_cgi_fds[0];
 		hctx->cgi_pid = cgi_pid_add(p, pid, hctx);
 
 		if (0 == r->reqbody_length) {
-			close(to_cgi_fds[1]);
+			close(to_cgi_fds[0]);
+		}
+		else if (-1 == to_cgi_fds[1]) {
+			chunkqueue * const cq = &r->reqbody_queue;
+			chunkqueue_mark_written(cq, chunkqueue_length(cq));
 		}
 		else if (0 == fdevent_fcntl_set_nb(to_cgi_fds[1])
 		         && 0 == cgi_write_request(hctx, to_cgi_fds[1])) {
+			close(to_cgi_fds[0]);
 			++r->con->srv->cur_fds;
 		}
 		else {
+			close(to_cgi_fds[0]);
 			close(to_cgi_fds[1]);
 			/*(hctx->fd not yet registered with fdevent, so manually
 			 * cleanup here; see fdevent_register() further below)*/
@@ -827,6 +882,18 @@ URIHANDLER_FUNC(cgi_is_handled) {
 	if (!S_ISREG(st->st_mode)) return HANDLER_GO_ON;
 	if (p->conf.execute_x_only == 1 && (st->st_mode & (S_IXUSR | S_IXGRP | S_IXOTH)) == 0) return HANDLER_GO_ON;
 
+	if (r->reqbody_length
+	    && p->tempfile_accum
+	    && !(r->conf.stream_request_body /*(if not streaming request body)*/
+	         & (FDEVENT_STREAM_REQUEST|FDEVENT_STREAM_REQUEST_BUFMIN))) {
+		/* store request body in single tempfile if not streaming request body*/
+		chunkqueue * const cq = &r->reqbody_queue;
+		chunkqueue_set_tempdirs(cq, cq->tempdirs, INTMAX_MAX);
+		/* force huge cq->upload_temp_file_size since chunkqueue_set_tempdirs()
+		 * might truncate upload_temp_file_size to chunk.c:MAX_TEMPFILE_SIZE */
+		cq->upload_temp_file_size = INTMAX_MAX;
+	}
+
 	{
 		handler_ctx *hctx = cgi_handler_ctx_init();
 		hctx->ev = r->con->srv->ev;