hw/xen: Use xs_node_read() from xs_node_vscanf()

Reduce some duplication.

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Anthony PERARD <anthony.perard@vates.tech>
Acked-by: Roger Pau Monné <roger.pau@citrix.com>

hw/xen/trace-events

@@ -38,7 +38,6 @@ xen_device_remove_watch(const char *type, char *name, const char *node, const ch
 xs_node_create(const char *node) "%s"
 xs_node_destroy(const char *node) "%s"
 xs_node_vprintf(char *path, char *value) "%s %s"
-xs_node_vscanf(char *path, char *value) "%s %s"
 xs_node_read(const char *path, const char *value) "%s %s"
 xs_node_watch(char *path) "%s"
 xs_node_unwatch(char *path) "%s"

hw/xen/xen-bus-helper.c

@@ -105,25 +105,22 @@ int xs_node_vscanf(struct qemu_xs_handle *h,  xs_transaction_t tid,
                    const char *node, const char *key, Error **errp,
                    const char *fmt, va_list ap)
 {
-    char *path, *value;
+    char *value;
     int rc;
 
-    path = (strlen(node) != 0) ? g_strdup_printf("%s/%s", node, key) :
-        g_strdup(key);
-    value = qemu_xen_xs_read(h, tid, path, NULL);
-
-    trace_xs_node_vscanf(path, value);
+    if (node && strlen(node) != 0) {
+        value = xs_node_read(h, tid, NULL, errp, "%s/%s", node, key);
+    } else {
+        value = xs_node_read(h, tid, NULL, errp, "%s", key);
+    }
 
     if (value) {
         rc = vsscanf(value, fmt, ap);
     } else {
-        error_setg_errno(errp, errno, "failed to read from '%s'",
-                         path);
         rc = EOF;
     }
 
     free(value);
-    g_free(path);
 
     return rc;
 }