Router: fixing error handling in config request.

The controller process awaits the response from the router for every
configration change request.  This patch adds error reporting for various error
conditions which may happen because of file descriptors or memory shortage.

Lack of a response lead to the controller awaiting the response, thus being
unable to process other client reconfiguration requests that also became stuck.

1 files changed, 42 insertions, 19 deletions

diff --git a/src/nxt_router.c b/src/nxt_router.c
index 8d6e493d..d9c722dd 100644
--- a/src/nxt_router.c
+++ b/src/nxt_router.c
@@ -699,26 +699,39 @@ nxt_router_conf_data_handler(nxt_task_t *task, nxt_port_recv_msg_t *msg)
     void                    *p;
     size_t                  size;
     nxt_int_t               ret;
+    nxt_port_t              *port;
     nxt_router_temp_conf_t  *tmcf;
 
+    port = nxt_runtime_port_find(task->thread->runtime,
+                                 msg->port_msg.pid,
+                                 msg->port_msg.reply_port);
+    if (nxt_slow_path(port == NULL)) {
+        nxt_alert(task, "conf_data_handler: reply port not found");
+        return;
+    }
+
+    p = MAP_FAILED;
+
+    /*
+     * Ancient compilers like gcc 4.8.5 on CentOS 7 wants 'size' to be
+     * initialized in 'cleanup' section.
+     */
+    size = 0;
+
     tmcf = nxt_router_temp_conf(task);
     if (nxt_slow_path(tmcf == NULL)) {
-        return;
+        goto fail;
     }
 
     if (nxt_slow_path(msg->fd[0] == -1)) {
-        nxt_alert(task, "conf_data_handler: invalid file shm fd");
-        return;
+        nxt_alert(task, "conf_data_handler: invalid shm fd");
+        goto fail;
     }
 
     if (nxt_buf_mem_used_size(&msg->buf->mem) != sizeof(size_t)) {
         nxt_alert(task, "conf_data_handler: unexpected buffer size (%d)",
                   (int) nxt_buf_mem_used_size(&msg->buf->mem));
-
-        nxt_fd_close(msg->fd[0]);
-        msg->fd[0] = -1;
-
-        return;
+        goto fail;
     }
 
     nxt_memcpy(&size, msg->buf->mem.pos, sizeof(size_t));
@@ -729,22 +742,14 @@ nxt_router_conf_data_handler(nxt_task_t *task, nxt_port_recv_msg_t *msg)
     msg->fd[0] = -1;
 
     if (nxt_slow_path(p == MAP_FAILED)) {
-        return;
+        goto fail;
     }
 
     nxt_debug(task, "conf_data_handler(%uz): %*s", size, size, p);
 
     tmcf->router_conf->router = nxt_router;
     tmcf->stream = msg->port_msg.stream;
-    tmcf->port = nxt_runtime_port_find(task->thread->runtime,
-                                       msg->port_msg.pid,
-                                       msg->port_msg.reply_port);
-
-    if (nxt_slow_path(tmcf->port == NULL)) {
-        nxt_alert(task, "reply port not found");
-
-        goto fail;
-    }
+    tmcf->port = port;
 
     nxt_port_use(task, tmcf->port, 1);
 
@@ -757,9 +762,27 @@ nxt_router_conf_data_handler(nxt_task_t *task, nxt_port_recv_msg_t *msg)
         nxt_router_conf_error(task, tmcf);
     }
 
+    goto cleanup;
+
 fail:
 
-    nxt_mem_munmap(p, size);
+    nxt_port_socket_write(task, port, NXT_PORT_MSG_RPC_ERROR, -1,
+                          msg->port_msg.stream, 0, NULL);
+
+    if (tmcf != NULL) {
+        nxt_mp_destroy(tmcf->mem_pool);
+    }
+
+cleanup:
+
+    if (p != MAP_FAILED) {
+        nxt_mem_munmap(p, size);
+    }
+
+    if (msg->fd[0] != -1) {
+        nxt_fd_close(msg->fd[0]);
+        msg->fd[0] = -1;
+    }
 }