[mod_cgi] simplify mod_cgi_handle_subrequest()

wait for CGI to close stdout, so we read EOF on pipe to end CGI response

remove extra call to waitpid() which will occur after process exits
if it has not already been explicitly closed by CGI (and has not been
inherited by CGI forked children)  (If CGI forks, then it should close
its stdout response pipe when response is done, especially if it intends
to perform lengthy post-processing in the background.)

From: Glenn Strauss <gstrauss@gluelogic.com>

git-svn-id: svn://svn.lighttpd.net/lighttpd/branches/lighttpd-1.4.x@3091 152afb58-edef-0310-8abb-c4023f1b3aa9

NEWS

@@ -21,6 +21,7 @@ NEWS
   * [mod_fastcgi] 404 for X-Sendfile file not found (fixes #2474)
   * [mod_cgi] send 500 if CGI ends and there is no response (fixes #2542)
   * [mod_cgi] consolidate CGI cleanup code
+  * [mod_cgi] simplify mod_cgi_handle_subrequest()
 
 - 1.4.39 - 2016-01-02
   * [core] fix memset_s call (fixes #2698)

src/mod_cgi.c

@@ -1338,9 +1338,9 @@ TRIGGER_FUNC(cgi_trigger) {
  * - HANDLER_WAIT_FOR_EVENT: waiting for response
  */
 SUBREQUEST_FUNC(mod_cgi_handle_subrequest) {
-	int status;
 	plugin_data *p = p_d;
 	handler_ctx *hctx = con->plugin_ctx[p->id];
+	UNUSED(srv);
 
 	if (con->mode != p->id) return HANDLER_GO_ON;
 	if (NULL == hctx) return HANDLER_GO_ON;
@@ -1349,42 +1349,8 @@ SUBREQUEST_FUNC(mod_cgi_handle_subrequest) {
 	log_error_write(srv, __FILE__, __LINE__, "sdd", "subrequest, pid =", hctx, hctx->pid);
 #endif
 
-#ifndef __WIN32
-	switch(waitpid(hctx->pid, &status, WNOHANG)) {
-	case 0:
-		return HANDLER_WAIT_FOR_EVENT;
-
-	case -1:
-		if (errno == EINTR) return HANDLER_WAIT_FOR_EVENT;
-
-		hctx->pid = 0;
-		if (errno != ECHILD) {
-			log_error_write(srv, __FILE__, __LINE__, "ss", "waitpid failed: ", strerror(errno));
-		}
-		break;
-
-	default:
-		/* cgi process exited
-		 */
-
-		hctx->pid = 0;
-
-		if (!WIFEXITED(status)) {
-			log_error_write(srv, __FILE__, __LINE__, "s", "cgi died ?");
-		}
-
-		if (cgi_demux_response(srv, hctx) == FDEVENT_HANDLED_ERROR) {
-			log_error_write(srv, __FILE__, __LINE__, "s", "demuxer failed: ");
-		}
-
-		break;
-	}
-
-	cgi_connection_close(srv, hctx);
-	return HANDLER_FINISHED;
-#else
-	return HANDLER_ERROR;
-#endif
+	/* if not done, wait for CGI to close stdout, so we read EOF on pipe */
+	return con->file_finished ? HANDLER_FINISHED : HANDLER_WAIT_FOR_EVENT;
 }