util: storage: Report errors when source host data is missing

Merge the reporting of the missing source host data into the parser
functions so that callers don't have to do it separately.

src/util/virstoragefile.c

@@ -2798,8 +2798,18 @@ static int
 virStorageSourceParseBackingJSONInetSocketAddress(virStorageNetHostDefPtr host,
                                                   virJSONValuePtr json)
 {
-    const char *hostname = virJSONValueObjectGetString(json, "host");
-    const char *port = virJSONValueObjectGetString(json, "port");
+    const char *hostname;
+    const char *port;
+
+    if (!json) {
+        virReportError(VIR_ERR_INVALID_ARG, "%s",
+                       _("missing remote server specification in JSON "
+                         "backing volume definition"));
+        return -1;
+    }
+
+    hostname = virJSONValueObjectGetString(json, "host");
+    port = virJSONValueObjectGetString(json, "port");
 
     if (!hostname) {
         virReportError(VIR_ERR_INVALID_ARG, "%s",
@@ -2822,10 +2832,17 @@ static int
 virStorageSourceParseBackingJSONSocketAddress(virStorageNetHostDefPtr host,
                                               virJSONValuePtr json)
 {
-    const char *type = virJSONValueObjectGetString(json, "type");
-    const char *socket = virJSONValueObjectGetString(json, "socket");
+    const char *type;
+    const char *socket;
+
+    if (!json) {
+        virReportError(VIR_ERR_INVALID_ARG, "%s",
+                       _("missing remote server specification in JSON "
+                         "backing volume definition"));
+        return -1;
+    }
 
-    if (!type) {
+    if (!(type = virJSONValueObjectGetString(json, "type"))) {
         virReportError(VIR_ERR_INVALID_ARG, "%s",
                        _("missing socket address type in "
                          "JSON backing volume definition"));
@@ -2838,7 +2855,7 @@ virStorageSourceParseBackingJSONSocketAddress(virStorageNetHostDefPtr host,
     } else if (STREQ(type, "unix")) {
         host->transport = VIR_STORAGE_NET_HOST_TRANS_UNIX;
 
-        if (!socket) {
+        if (!(socket = virJSONValueObjectGetString(json, "socket"))) {
             virReportError(VIR_ERR_INVALID_ARG, "%s",
                            _("missing socket path for udp backing server in "
                              "JSON backing volume definition"));