[libvirt] [PATCH 4/4] qemu: snapshot: Fix return value of external checkpoint with no disks

[Peter Krempa]

When doing an external checkpoint of a VM with no disk selected we'd
return failure but not set error code. This was a result of ret not
being set to 0 during walking of the disk array.

Rework early failure checking to avoid the problem.

Fixes the following symptom (or without --diskspec for diskless VMs)

 $ virsh snapshot-create-as snapshot-test  --memspec /tmp/asdf --diskspec hda,snapshot=no
 error: An error occurred, but the cause is unknown
---
 src/qemu/qemu_driver.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index 6442b3f..460c680 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -13010,17 +13010,17 @@ qemuDomainSnapshotCreateDiskActive(virQEMUDriverPtr driver,
 {
     qemuDomainObjPrivatePtr priv = vm->privateData;
     virJSONValuePtr actions = NULL;
-    int ret = -1;
+    int ret = 0;
     size_t i;
     bool persist = false;
     bool reuse = (flags & VIR_DOMAIN_SNAPSHOT_CREATE_REUSE_EXT) != 0;
-    virQEMUDriverConfigPtr cfg = virQEMUDriverGetConfig(driver);
+    virQEMUDriverConfigPtr cfg = NULL;
     virErrorPtr orig_err = NULL;

     if (!virDomainObjIsActive(vm)) {
         virReportError(VIR_ERR_OPERATION_INVALID,
                        "%s", _("domain is not running"));
-        goto cleanup;
+        return -1;
     }

     if (virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_TRANSACTION)) {
@@ -13030,9 +13030,11 @@ qemuDomainSnapshotCreateDiskActive(virQEMUDriverPtr driver,
         virReportError(VIR_ERR_OPERATION_UNSUPPORTED, "%s",
                        _("live disk snapshot not supported with this "
                          "QEMU binary"));
-        goto cleanup;
+        return -1;
     }

+    cfg = virQEMUDriverGetConfig(driver);
+
     /* No way to roll back if first disk succeeds but later disks
      * fail, unless we have transaction support.
      * Based on earlier qemuDomainSnapshotPrepare, all
-- 
1.9.3