[Xen-devel] [PATCH V2 08/11] libxl_qmp, Introduce qmp_request_handle.

[Anthony PERARD <anthony.perard@xxxxxxxxxx>]

This structure helps keep the return code of the callback, so a caller can read
it.

Signed-off-by: Anthony PERARD <anthony.perard@xxxxxxxxxx>
---
 tools/libxl/libxl_qmp.c |   71 +++++++++++++++++++++++++++++-----------------
 1 files changed, 45 insertions(+), 26 deletions(-)

diff --git a/tools/libxl/libxl_qmp.c b/tools/libxl/libxl_qmp.c
index 5ea9429..547cd53 100644
--- a/tools/libxl/libxl_qmp.c
+++ b/tools/libxl/libxl_qmp.c
@@ -46,10 +46,16 @@ typedef int (*qmp_callback_t)(libxl__qmp_handler *qmp,
                               const libxl__json_object *tree,
                               void *opaque);
 
-typedef struct callback_id_pair {
-    int id;
+typedef struct qmp_request_handle {
     qmp_callback_t callback;
     void *opaque;
+    /* return code of the callback */
+    int rc;
+} qmp_request_handle;
+typedef struct callback_id_pair {
+    qmp_request_handle *handle;
+    bool free_it; /* tell if handle need to be freed */
+    int id;
     SIMPLEQ_ENTRY(callback_id_pair) next;
 } callback_id_pair;
 
@@ -73,7 +79,7 @@ struct libxl__qmp_handler {
 
 static int qmp_send(libxl__qmp_handler *qmp,
                     const char *cmd, libxl_key_value_list *args,
-                    qmp_callback_t callback, void *opaque);
+                    qmp_request_handle *handle, bool free_it);
 
 static const int QMP_SOCKET_CONNECT_TIMEOUT = 5;
 
@@ -161,8 +167,9 @@ static int qmp_capabilities_callback(libxl__qmp_handler 
*qmp,
 
 static int enable_qmp_capabilities(libxl__qmp_handler *qmp)
 {
-    return qmp_send(qmp, "qmp_capabilities", NULL,
-                    qmp_capabilities_callback, NULL);
+    qmp_request_handle *h = calloc(1, sizeof (qmp_request_handle));
+    h->callback = qmp_capabilities_callback;
+    return qmp_send(qmp, "qmp_capabilities", NULL, h, 1);
 }
 
 /*
@@ -213,14 +220,17 @@ static void qmp_handle_error_response(libxl__qmp_handler 
*qmp,
     resp = libxl__json_map_get("desc", resp, JSON_STRING);
 
     if (pp) {
-        if (pp->callback) {
-            pp->callback(qmp, NULL, pp->opaque);
+        qmp_request_handle *h = pp->handle;
+        if (h) {
+            h->rc = h->callback(qmp, NULL, h->opaque);
         }
         if (pp->id == qmp->wait_for_id) {
             /* tell that the id have been processed */
             qmp->wait_for_id = 0;
         }
         SIMPLEQ_REMOVE(&qmp->callback_list, pp, callback_id_pair, next);
+        if (pp->free_it)
+            free(pp->handle);
         free(pp);
     }
 
@@ -241,31 +251,33 @@ static int qmp_handle_response(libxl__qmp_handler *qmp,
     switch (type) {
     case LIBXL__QMP_MESSAGE_TYPE_QMP:
         /* On the greeting message from the server, enable QMP capabilities */
-        enable_qmp_capabilities(qmp);
-        break;
+        return enable_qmp_capabilities(qmp);
     case LIBXL__QMP_MESSAGE_TYPE_RETURN: {
         callback_id_pair *pp = qmp_get_callback_from_id(qmp, resp);
 
         if (pp) {
-            if (pp->callback) {
-                pp->callback(qmp,
+            qmp_request_handle *h = pp->handle;
+            if (h) {
+                h->rc = h->callback(qmp,
                              libxl__json_map_get("return", resp, JSON_ANY),
-                             pp->opaque);
+                             h->opaque);
             }
             if (pp->id == qmp->wait_for_id) {
                 /* tell that the id have been processed */
                 qmp->wait_for_id = 0;
             }
             SIMPLEQ_REMOVE(&qmp->callback_list, pp, callback_id_pair, next);
+            if (pp->free_it)
+                free(pp->handle);
             free(pp);
         }
-        break;
+        return 0;
     }
     case LIBXL__QMP_MESSAGE_TYPE_ERROR:
         qmp_handle_error_response(qmp, resp);
-        break;
+        return -1;
     case LIBXL__QMP_MESSAGE_TYPE_EVENT:
-        break;
+        return 0;
     case LIBXL__QMP_MESSAGE_TYPE_INVALID:
         return -1;
     }
@@ -358,6 +370,7 @@ static int qmp_next(libxl__gc *gc, libxl__qmp_handler *qmp)
 
     char *incomplete = NULL;
     size_t incomplete_size = 0;
+    int rc = 0;
 
     do {
         fd_set rfds;
@@ -415,7 +428,7 @@ static int qmp_next(libxl__gc *gc, libxl__qmp_handler *qmp)
                 o = libxl__json_parse(gc, s);
 
                 if (o) {
-                    qmp_handle_response(qmp, o);
+                    rc = qmp_handle_response(qmp, o);
                     libxl__json_object_free(gc, o);
                 } else {
                     LIBXL__LOG(qmp->ctx, LIBXL__LOG_ERROR,
@@ -430,12 +443,12 @@ static int qmp_next(libxl__gc *gc, libxl__qmp_handler 
*qmp)
         } while (s < s_end);
    } while (s < s_end);
 
-    return 1;
+    return rc;
 }
 
 static int qmp_send(libxl__qmp_handler *qmp,
                     const char *cmd, libxl_key_value_list *args,
-                    qmp_callback_t callback, void *opaque)
+                    qmp_request_handle *handle, bool free_it)
 {
     yajl_gen_config conf = { 0, NULL };
     const unsigned char *buf;
@@ -475,8 +488,8 @@ static int qmp_send(libxl__qmp_handler *qmp,
         goto error;
     }
     elm->id = qmp->last_id_used;
-    elm->callback = callback;
-    elm->opaque = opaque;
+    elm->handle = handle;
+    elm->free_it = free_it;
     SIMPLEQ_INSERT_TAIL(&qmp->callback_list, elm, next);
 
     LIBXL__LOG(qmp->ctx, LIBXL__LOG_DEBUG, "next qmp command: '%s'", buf);
@@ -499,14 +512,14 @@ error:
 
 static int qmp_synchronous_send(libxl__qmp_handler *qmp, const char *cmd,
                                 libxl_key_value_list *args,
-                                qmp_callback_t callback, void *opaque,
+                                qmp_request_handle *handle,
                                 int ask_timeout)
 {
     int id = 0;
     int ret = 0;
     libxl__gc gc = LIBXL_INIT_GC(qmp->ctx);
 
-    id = qmp_send(qmp, cmd, args, callback, opaque);
+    id = qmp_send(qmp, cmd, args, handle, 0);
     if (id <= 0) {
         return -1;
     }
@@ -594,10 +607,16 @@ void libxl__qmp_cleanup(libxl__gc *gc, uint32_t domid)
 
 int libxl__qmp_query_serial(libxl__qmp_handler *qmp)
 {
-    return qmp_synchronous_send(qmp, "query-chardev", NULL,
-                                register_serials_chardev_callback,
-                                NULL,
-                                qmp->timeout);
+    int rc = 0;
+    qmp_request_handle request = {
+        .callback = register_serials_chardev_callback,
+    };
+    rc = qmp_synchronous_send(qmp, "query-chardev", NULL,
+                              &request, qmp->timeout);
+    if (rc == 0) {
+        rc = request.rc;
+    }
+    return rc;
 }
 
 int libxl__qmp_initializations(libxl_ctx *ctx, uint32_t domid)
-- 
Anthony PERARD


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