qemu: Don't bother user with libvirt-internal paths

If user defines a virtio channel with UNIX socket backend and doesn't
care about the path for the socket (e.g. qemu-agent channel), we still
generate it into the persistent XML.  Moreover when then user renames
the domain, due to its persistent socket path saved into the per-domain
directory, it will not start.  So let's forget about old generated paths
and also stop putting them into the persistent definition.

https://bugzilla.redhat.com/show_bug.cgi?id=1278068

Signed-off-by: Martin Kletzander <mkletzan@redhat.com>

src/qemu/qemu_command.c

@@ -10510,6 +10510,23 @@ qemuBuildCommandLine(virConnectPtr conn,
                 goto error;
             }
 
+            /*
+             * TODO: Refactor so that we generate this (and onther
+             * things) somewhere else then where we are building the
+             * command line.
+             */
+            if (channel->source.type == VIR_DOMAIN_CHR_TYPE_UNIX &&
+                !channel->source.data.nix.path) {
+                if (virAsprintf(&channel->source.data.nix.path,
+                                "%s/domain-%s/%s",
+                                cfg->channelTargetDir, def->name,
+                                channel->target.name ? channel->target.name
+                                : "unknown.sock") < 0)
+                    goto error;
+
+                channel->source.data.nix.listen = true;
+            }
+
             if (virQEMUCapsGet(qemuCaps, QEMU_CAPS_DEVICE_SPICEVMC) &&
                 channel->source.type == VIR_DOMAIN_CHR_TYPE_SPICEVMC) {
                 /* spicevmc was originally introduced via a -device

src/qemu/qemu_domain.c

@@ -1329,20 +1329,21 @@ qemuDomainDeviceDefPostParse(virDomainDeviceDefPtr dev,
         ARCH_IS_S390(def->os.arch))
         dev->data.controller->model = VIR_DOMAIN_CONTROLLER_MODEL_SCSI_VIRTIO_SCSI;
 
-    /* auto generate unix socket path */
+    /* clear auto generated unix socket path */
     if (dev->type == VIR_DOMAIN_DEVICE_CHR &&
         dev->data.chr->deviceType == VIR_DOMAIN_CHR_DEVICE_TYPE_CHANNEL &&
         dev->data.chr->targetType == VIR_DOMAIN_CHR_CHANNEL_TARGET_TYPE_VIRTIO &&
         dev->data.chr->source.type == VIR_DOMAIN_CHR_TYPE_UNIX &&
-        !dev->data.chr->source.data.nix.path) {
+        dev->data.chr->source.data.nix.path &&
-        if (virAsprintf(&dev->data.chr->source.data.nix.path,
+        STRPREFIX(dev->data.chr->source.data.nix.path, cfg->channelTargetDir)) {
-                        "%s/domain-%s/%s",
+        /*
-                        cfg->channelTargetDir, def->name,
+         * If the address is generated by us (starts with our
-                        dev->data.chr->target.name ? dev->data.chr->target.name
+         * channel dir), we should not keep it in the persistent
-                        : "unknown.sock") < 0)
+         * XML.  If libvirt is the one who generated it, users
-            goto cleanup;
+         * shouldn't care about that.  If they do, they are
-
+         * supposed to set it themselves.
-        dev->data.chr->source.data.nix.listen = true;
+         */
+        VIR_FREE(dev->data.chr->source.data.nix.path);
     }
 
     /* forbid capabilities mode hostdev in this kind of hypervisor */

tests/qemuxml2argvdata/qemuxml2argv-channel-virtio-unix.args

@@ -33,4 +33,7 @@ nowait \
 id=channel1 \
 -chardev socket,id=charchannel2,path=/tmp/domain-QEMUGuest1/ble,server,nowait \
 -device virtserialport,bus=virtio-serial0.0,nr=3,chardev=charchannel2,\
-id=channel2,name=ble
+id=channel2,name=ble \
+-chardev socket,id=charchannel3,path=/tmp/domain-QEMUGuest1/fdsa,server,nowait \
+-device virtserialport,bus=virtio-serial0.0,nr=4,chardev=charchannel3,\
+id=channel3,name=fdsa

tests/qemuxml2argvdata/qemuxml2argv-channel-virtio-unix.xml

@@ -32,6 +32,10 @@
     <channel type='unix'>
       <target type='virtio' name='ble'/>
     </channel>
+    <channel type='unix'>
+      <source path='/tmp/domain-oldname/fdsa'/>
+      <target type='virtio' name='fdsa'/>
+    </channel>
     <memballoon model='none'/>
   </devices>
 </domain>