[PATCH 2/2] xen: do not use '%ms' scanf specifier

[Roger Pau Monne]

The 'm' parameter used to request auto-allocation of the destination variable
is not supported on FreeBSD, and as such leads to failures to parse.

What's more, the current usage of '%ms' with xs_node_scanf() is pointless, as
it just leads to a double allocation of the same string.  Instead use
qemu_xen_xs_read() to read the whole xenstore node.

Fixes: a783f8ad4ec9 ('xen: add a mechanism to automatically create 
XenDevice-s...')
Fixes: 9b7737469080 ('hw/xen: update Xen console to XenDevice model')
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
---
Cc: Stefano Stabellini <sstabellini@kernel.org>
Cc: Anthony PERARD <anthony@xenproject.org>
Cc: Paul Durrant <paul@xen.org>
Cc: "Edgar E. Iglesias" <edgar.iglesias@gmail.com>
Cc: "Marc-André Lureau" <marcandre.lureau@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: xen-devel@lists.xenproject.org
---
 hw/char/xen_console.c | 11 +++++++++--
 hw/xen/xen-bus.c      |  7 +++++--
 2 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/hw/char/xen_console.c b/hw/char/xen_console.c
index af706c7ef440..18afd214c2f6 100644
--- a/hw/char/xen_console.c
+++ b/hw/char/xen_console.c
@@ -531,6 +531,7 @@ static void xen_console_device_create(XenBackendInstance 
*backend,
     const char *name = xen_backend_get_name(backend);
     unsigned long number;
     char *fe = NULL, *type = NULL, *output = NULL;
+    const char *node_path;
     char label[32];
     XenDevice *xendev = NULL;
     XenConsole *con;
@@ -550,7 +551,10 @@ static void xen_console_device_create(XenBackendInstance 
*backend,
         goto fail;
     }
 
-    if (xs_node_scanf(xsh, XBT_NULL, fe, "type", errp, "%ms", &type) != 1) {
+    node_path = g_strdup_printf("%s/type", fe);
+    type = qemu_xen_xs_read(xsh, XBT_NULL, node_path, NULL);
+    g_free(node_path);
+    if (!type) {
         error_setg(errp, "failed to read console device type: ");
         goto fail;
     }
@@ -568,7 +572,10 @@ static void xen_console_device_create(XenBackendInstance 
*backend,
 
     snprintf(label, sizeof(label), "xencons%ld", number);
 
-    if (xs_node_scanf(xsh, XBT_NULL, fe, "output", NULL, "%ms", &output) == 1) 
{
+    node_path = g_strdup_printf("%s/output", fe);
+    output = qemu_xen_xs_read(xsh, XBT_NULL, node_path, NULL);
+    g_free(node_path);
+    if (!output) {
         /*
          * FIXME: sure we want to support implicit
          * muxed monitors here?
diff --git a/hw/xen/xen-bus.c b/hw/xen/xen-bus.c
index adfc4efad035..9be807649e77 100644
--- a/hw/xen/xen-bus.c
+++ b/hw/xen/xen-bus.c
@@ -142,6 +142,7 @@ again:
 
     opts = qdict_new();
     for (i = 0; i < n; i++) {
+        const char *node_path;
         char *val;
 
         /*
@@ -156,8 +157,10 @@ again:
             !strcmp(key[i], "hotplug-status"))
             continue;
 
-        if (xs_node_scanf(xenbus->xsh, tid, path, key[i], NULL, "%ms",
-                          &val) == 1) {
+        node_path = g_strdup_printf("%s/%s", path, key[i]);
+        val = qemu_xen_xs_read(xenbus->xsh, tid, node_path, NULL);
+        g_free(node_path);
+        if (val) {
             qdict_put_str(opts, key[i], val);
             free(val);
         }
-- 
2.46.0