hw/xen: Add xs_node_read() helper function

This returns the full contents of the node, having created the node path
from the printf-style format string provided in its arguments.

This will save various callers from having to do so for themselves (and
from using xs_node_scanf() with the non-portable %ms format string.

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
[remove double newline and constify trace parameters]
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Anthony PERARD <anthony.perard@vates.tech>

1 files changed, 9 insertions, 0 deletions

diff --git a/include/hw/xen/xen-bus-helper.h b/include/hw/xen/xen-bus-helper.h
index d8dcc2f010..e9911115b3 100644
--- a/include/hw/xen/xen-bus-helper.h
+++ b/include/hw/xen/xen-bus-helper.h
@@ -38,6 +38,15 @@ int xs_node_scanf(struct qemu_xs_handle *h,  xs_transaction_t tid,
                   const char *fmt, ...)
     G_GNUC_SCANF(6, 7);
 
+/*
+ * Unlike other functions here, the printf-formatted path_fmt is for
+ * the XenStore path, not the contents of the node.
+ */
+char *xs_node_read(struct qemu_xs_handle *h, xs_transaction_t tid,
+                   unsigned int *len, Error **errp,
+                   const char *path_fmt, ...)
+    G_GNUC_PRINTF(5, 6);
+
 /* Watch node/key unless node is empty, in which case watch key */
 struct qemu_xs_watch *xs_node_watch(struct qemu_xs_handle *h, const char *node,
                                     const char *key, xs_watch_fn fn,