[libvirt] [PATCH] qemu: add return value check

[Eric Blake]

On 09/26/2011 01:52 AM, ajia at redhat.com wrote:
> From: Alex Jia<ajia at redhat.com>
>
> * src/qemu/qemu_migration.c: if 'vmdef' is NULL, the function
>    virDomainSaveConfig still dereferences it, it doesn't make
>    sense, so should add return value check to make sure 'vmdef'
>    is non-NULL before calling virDomainSaveConfig.
>
> Signed-off-by: Alex Jia<ajia at redhat.com>
> ---
>   src/qemu/qemu_migration.c |    8 +++++++-
>   1 files changed, 7 insertions(+), 1 deletions(-)

Good catch, but not quite the right fix.

> +++ b/src/qemu/qemu_migration.c
> @@ -2580,8 +2580,14 @@ qemuMigrationFinish(struct qemud_driver *driver,
>               vm->persistent = 1;
>               if (mig->persistent)
>                   vm->newDef = vmdef = mig->persistent;
> -            else
> +            else {

This violates formatting conventions (if one side of if-else uses {}, 
then both must use it).

>                   vmdef = virDomainObjGetPersistentDef(driver->caps, vm);
> +                if (!vmdef) {
> +                    qemuReportError(VIR_ERR_INTERNAL_ERROR, "%s",
> +                                    _("can't get vmdef"));
> +                    goto endjob;

This is wrong for v3proto.  A better fix is probably this one, although 
I'd feel more comfortable with Dan reviewing it and/or running the TCK 
migration stress test on it:

diff --git i/src/qemu/qemu_migration.c w/src/qemu/qemu_migration.c
index 0a5a13d..1bef50a 100644
--- i/src/qemu/qemu_migration.c
+++ w/src/qemu/qemu_migration.c
@@ -2582,7 +2582,8 @@ qemuMigrationFinish(struct qemud_driver *driver,
                  vm->newDef = vmdef = mig->persistent;
              else
                  vmdef = virDomainObjGetPersistentDef(driver->caps, vm);
-            if (virDomainSaveConfig(driver->configDir, vmdef) < 0) {
+            if (!vmdef ||
+                virDomainSaveConfig(driver->configDir, vmdef) < 0) {
                  /* Hmpf.  Migration was successful, but making it 
persistent
                   * was not.  If we report successful, then when this 
domain
                   * shuts down, management tools are in for a surprise. 
  On the


-- 
Eric Blake   eblake at redhat.com    +1-801-349-2682
Libvirt virtualization library http://libvirt.org