[PULL 4/4] qga: Use qemu_get_host_name() instead of g_get_host_name()

From: Michael Roth <mdroth@linux.vnet.ibm.com>
To: qemu-devel@nongnu.org
Cc: peter.maydell@linaro.org, qemu-stable@nongnu.org,
	Michal Privoznik <mprivozn@redhat.com>
Subject: [PULL 4/4] qga: Use qemu_get_host_name() instead of g_get_host_name()
Date: Mon, 13 Jul 2020 23:51:14 -0500	[thread overview]
Message-ID: <20200714045114.29319-5-mdroth@linux.vnet.ibm.com> (raw)
In-Reply-To: <20200714045114.29319-1-mdroth@linux.vnet.ibm.com>

From: Michal Privoznik <mprivozn@redhat.com>

Problem with g_get_host_name() is that on the first call it saves
the hostname into a global variable and from then on, every
subsequent call returns the saved hostname. Even if the hostname
changes. This doesn't play nicely with guest agent, because if
the hostname is acquired before the guest is set up (e.g. on the
first boot, or before DHCP) we will report old, invalid hostname.

Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1845127

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Cc: qemu-stable@nongnu.org
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
---
 qga/commands.c | 17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)

diff --git a/qga/commands.c b/qga/commands.c
index efc8b90281..d3fec807c1 100644
--- a/qga/commands.c
+++ b/qga/commands.c
@@ -515,11 +515,20 @@ int ga_parse_whence(GuestFileWhence *whence, Error **errp)
 GuestHostName *qmp_guest_get_host_name(Error **errp)
 {
     GuestHostName *result = NULL;
-    gchar const *hostname = g_get_host_name();
-    if (hostname != NULL) {
-        result = g_new0(GuestHostName, 1);
-        result->host_name = g_strdup(hostname);
+    g_autofree char *hostname = qemu_get_host_name(errp);
+
+    /*
+     * We want to avoid using g_get_host_name() because that
+     * caches the result and we wouldn't reflect changes in the
+     * host name.
+     */
+
+    if (!hostname) {
+        hostname = g_strdup("localhost");
     }
+
+    result = g_new0(GuestHostName, 1);
+    result->host_name = g_steal_pointer(&hostname);
     return result;
 }
 
-- 
2.17.1


