[libvirt] dname parameter ignored in qemudDomainMigratePrepareTunnel{, 2}

[Jim Meyering]

clang warned about a dead-store in src/qemu/qemu_driver.c,
since dname is never used thereafter:

    http://libvirt.org/git/?p=libvirt.git;a=blob;f=src/qemu/qemu_driver.c;h=0d77d572a49e1c86f86911bce54d93fdb4a38feb;hb=HEAD#l7436
    /* Target domain name, maybe renamed. */
    dname = dname ? dname : def->name;

That stmt was initially added with a following use,

    if (!vm) vm = virDomainFindByName(&driver->domains, dname);

But the use was removed by this commit, rendering the store "dead",
and the dname parameter effectively unused:

    http://libvirt.org/git/?p=libvirt.git;a=commitdiff;h=c26cb9234f4b9fa46d7caa3385ae36704167c53f

The same thing happened in both
qemudDomainMigratePrepareTunnel and
qemudDomainMigratePrepareTunnel2

Shouldn't they be doing something like this instead?

    if (dname)
        def->name = dname;

But def->name is already allocated.  Better free it first.
And is dname "known" to be allocated from the heap?
That's not clear from the little documentation I've read so far,
so I've strdup'd it below:

Here's a possible patch:

>From b51a39aed62ee5c8db733cecfe6eef0c34a7f989 Mon Sep 17 00:00:00 2001
From: Jim Meyering <meyering at redhat.com>
Date: Thu, 11 Feb 2010 16:46:21 +0100
Subject: [PATCH] qemu_driver.c: honor dname parameter once again

Since c26cb9234f4b9fa46d7caa3385ae36704167c53f, the dname
parameter has been ignored by these two functions.  Use it.
* src/qemu/qemu_driver.c (qemudDomainMigratePrepareTunnel): Honor dname
parameter once again.
(qemudDomainMigratePrepare2): Likewise.
---
 src/qemu/qemu_driver.c |   14 ++++++++++++--
 1 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index 0d77d57..9ff712c 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -7434,7 +7434,12 @@ qemudDomainMigratePrepareTunnel(virConnectPtr dconn,
     }

     /* Target domain name, maybe renamed. */
-    dname = dname ? dname : def->name;
+    if (dname) {
+        VIR_FREE(def->name);
+        def->name = strdup(dname);
+        if (def->name == NULL)
+            goto cleanup;
+    }

     if (virDomainObjIsDuplicate(&driver->domains, def, 1) < 0)
         goto cleanup;
@@ -7660,7 +7665,12 @@ qemudDomainMigratePrepare2 (virConnectPtr dconn,
     }

     /* Target domain name, maybe renamed. */
-    dname = dname ? dname : def->name;
+    if (dname) {
+        VIR_FREE(def->name);
+        def->name = strdup(dname);
+        if (def->name == NULL)
+            goto cleanup;
+    }

     if (virDomainObjIsDuplicate(&driver->domains, def, 1) < 0)
         goto cleanup;
--
1.7.0.rc2.170.gbc565