qemuBuildChannelsCommandLine: Extract common formatting of 'chardev'

Both active branches create the same backend chardev. Since there is no
other case, extract it before the switch so that we don't have to
duplicate it.
Signed-off-by: NPeter Krempa <pkrempa@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>

src/qemu/qemu_command.c

@@ -8531,37 +8531,27 @@ qemuBuildChannelsCommandLine(virLogManagerPtr logManager,
 
     for (i = 0; i < def->nchannels; i++) {
         virDomainChrDefPtr channel = def->channels[i];
-        char *devstr;
+        g_autofree char *chardevstr = NULL;
+        g_autofree char *netdevstr = NULL;
 
-        switch ((virDomainChrChannelTargetType) channel->targetType) {
-        case VIR_DOMAIN_CHR_CHANNEL_TARGET_TYPE_GUESTFWD:
-            if (!(devstr = qemuBuildChrChardevStr(logManager, secManager,
+        if (!(chardevstr = qemuBuildChrChardevStr(logManager, secManager,
                                                   cmd, cfg, def,
                                                   channel->source,
                                                   channel->info.alias,
                                                   qemuCaps, cdevflags)))
-                return -1;
-            virCommandAddArg(cmd, "-chardev");
-            virCommandAddArg(cmd, devstr);
-            VIR_FREE(devstr);
+            return -1;
 
-            if (qemuBuildChrDeviceStr(&devstr, def, channel, qemuCaps) < 0)
+        virCommandAddArg(cmd, "-chardev");
+        virCommandAddArg(cmd, chardevstr);
+
+        switch ((virDomainChrChannelTargetType) channel->targetType) {
+        case VIR_DOMAIN_CHR_CHANNEL_TARGET_TYPE_GUESTFWD:
+            if (qemuBuildChrDeviceStr(&netdevstr, def, channel, qemuCaps) < 0)
                 return -1;
-            virCommandAddArgList(cmd, "-netdev", devstr, NULL);
-            VIR_FREE(devstr);
+            virCommandAddArgList(cmd, "-netdev", netdevstr, NULL);
             break;
 
         case VIR_DOMAIN_CHR_CHANNEL_TARGET_TYPE_VIRTIO:
-            if (!(devstr = qemuBuildChrChardevStr(logManager, secManager,
-                                                  cmd, cfg, def,
-                                                  channel->source,
-                                                  channel->info.alias,
-                                                  qemuCaps, cdevflags)))
-                return -1;
-            virCommandAddArg(cmd, "-chardev");
-            virCommandAddArg(cmd, devstr);
-            VIR_FREE(devstr);
-
             if (qemuBuildChrDeviceCommandLine(cmd, def, channel, qemuCaps) < 0)
                 return -1;
             break;