[libvirt] [PATCH v2 3/7] qemu: Refactor check for _LIVE vs. _REDEFINE

[Eric Blake]

The current qemu code rejects the combination of the two flags
VIR_DOMAIN_SNAPSHOT_CREATE_LIVE in tandem with
VIR_DOMAIN_SNAPSHOT_CREATE_REDEFINE, but rather late in the cycle
(after the snapshot was already parsed), and with a rather confusing
message (complaining that live snapshots require external storage,
even if the redefined snapshot already declares external storage).
Hoist the rejection message to occur earlier (before parsing any
XML, which also aids upcoming patches that will implement bulk
redefine), and with a more typical error message about mutually
exclusive flags.

Signed-off-by: Eric Blake <eblake at redhat.com>
---
 src/qemu/qemu_driver.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index 1d5b5f8653..4869096273 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -15707,6 +15707,9 @@ qemuDomainSnapshotCreateXML(virDomainPtr domain,
     VIR_REQUIRE_FLAG_RET(VIR_DOMAIN_SNAPSHOT_CREATE_QUIESCE,
                          VIR_DOMAIN_SNAPSHOT_CREATE_DISK_ONLY,
                          NULL);
+    VIR_EXCLUSIVE_FLAGS_RET(VIR_DOMAIN_SNAPSHOT_CREATE_LIVE,
+                            VIR_DOMAIN_SNAPSHOT_CREATE_REDEFINE,
+                            NULL);

     if ((redefine && !(flags & VIR_DOMAIN_SNAPSHOT_CREATE_CURRENT)) ||
         (flags & VIR_DOMAIN_SNAPSHOT_CREATE_NO_METADATA))
@@ -15767,8 +15770,7 @@ qemuDomainSnapshotCreateXML(virDomainPtr domain,
     /* reject the VIR_DOMAIN_SNAPSHOT_CREATE_LIVE flag where not supported */
     if (flags & VIR_DOMAIN_SNAPSHOT_CREATE_LIVE &&
         (!virDomainObjIsActive(vm) ||
-         def->memory != VIR_DOMAIN_SNAPSHOT_LOCATION_EXTERNAL ||
-         redefine)) {
+         def->memory != VIR_DOMAIN_SNAPSHOT_LOCATION_EXTERNAL)) {
         virReportError(VIR_ERR_OPERATION_UNSUPPORTED, "%s",
                        _("live snapshot creation is supported only "
                          "during full system snapshots"));
-- 
2.20.1