hmp: Allow for error message hints on HMP

Commits 7216ae3d and d2828429 disabled some error message hints,
all because a change to use modern error reporting meant that the
hint would be output prior to the actual error.  Fix this by making
hints a first-class member of Error.

For example, we are now back to the pleasant:

 $ qemu-system-x86_64 --nodefaults -S --vnc :0 --chardev null,id=,
 qemu-system-x86_64: --chardev null,id=,: Parameter 'id' expects an identifier
 Identifiers consist of letters, digits, '-', '.', '_', starting with a letter.

Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <1441901956-21991-1-git-send-email-eblake@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>

1 files changed, 14 insertions, 28 deletions

diff --git a/qdev-monitor.c b/qdev-monitor.c
index f9e2d62..0bf7f83 100644
--- a/qdev-monitor.c
+++ b/qdev-monitor.c
@@ -289,37 +289,35 @@ static Object *qdev_get_peripheral_anon(void)
     return dev;
 }
 
-#if 0 /* conversion from qerror_report() to error_set() broke their use */
-static void qbus_list_bus(DeviceState *dev)
+static void qbus_list_bus(DeviceState *dev, Error **errp)
 {
     BusState *child;
     const char *sep = " ";
 
-    error_printf("child buses at \"%s\":",
-                 dev->id ? dev->id : object_get_typename(OBJECT(dev)));
+    error_append_hint(errp, "child buses at \"%s\":",
+                      dev->id ? dev->id : object_get_typename(OBJECT(dev)));
     QLIST_FOREACH(child, &dev->child_bus, sibling) {
-        error_printf("%s\"%s\"", sep, child->name);
+        error_append_hint(errp, "%s\"%s\"", sep, child->name);
         sep = ", ";
     }
-    error_printf("\n");
 }
 
-static void qbus_list_dev(BusState *bus)
+static void qbus_list_dev(BusState *bus, Error **errp)
 {
     BusChild *kid;
     const char *sep = " ";
 
-    error_printf("devices at \"%s\":", bus->name);
+    error_append_hint(errp, "devices at \"%s\":", bus->name);
     QTAILQ_FOREACH(kid, &bus->children, sibling) {
         DeviceState *dev = kid->child;
-        error_printf("%s\"%s\"", sep, object_get_typename(OBJECT(dev)));
-        if (dev->id)
-            error_printf("/\"%s\"", dev->id);
+        error_append_hint(errp, "%s\"%s\"", sep,
+                          object_get_typename(OBJECT(dev)));
+        if (dev->id) {
+            error_append_hint(errp, "/\"%s\"", dev->id);
+        }
         sep = ", ";
     }
-    error_printf("\n");
 }
-#endif
 
 static BusState *qbus_find_bus(DeviceState *dev, char *elem)
 {
@@ -461,11 +459,7 @@ static BusState *qbus_find(const char *path, Error **errp)
         if (!dev) {
             error_set(errp, ERROR_CLASS_DEVICE_NOT_FOUND,
                       "Device '%s' not found", elem);
-#if 0 /* conversion from qerror_report() to error_set() broke this: */
-            if (!monitor_cur_is_qmp()) {
-                qbus_list_dev(bus);
-            }
-#endif
+            qbus_list_dev(bus, errp);
             return NULL;
         }
 
@@ -483,11 +477,7 @@ static BusState *qbus_find(const char *path, Error **errp)
             if (dev->num_child_bus) {
                 error_setg(errp, "Device '%s' has multiple child buses",
                            elem);
-#if 0 /* conversion from qerror_report() to error_set() broke this: */
-                if (!monitor_cur_is_qmp()) {
-                    qbus_list_bus(dev);
-                }
-#endif
+                qbus_list_bus(dev, errp);
             } else {
                 error_setg(errp, "Device '%s' has no child bus", elem);
             }
@@ -503,11 +493,7 @@ static BusState *qbus_find(const char *path, Error **errp)
         bus = qbus_find_bus(dev, elem);
         if (!bus) {
             error_setg(errp, "Bus '%s' not found", elem);
-#if 0 /* conversion from qerror_report() to error_set() broke this: */
-            if (!monitor_cur_is_qmp()) {
-                qbus_list_bus(dev);
-            }
-#endif
+            qbus_list_bus(dev, errp);
             return NULL;
         }
     }