[libvirt] [PATCH v2] qemu: qemuDomainChangeNet: validity checks should be done before XML autocompletion

[Katerina Koukiou]

This patch ensures that changes in attributes of interfaces will be emit
errors accept if they are missing from the XML.
Previously we were falsely reporting successfull updates, because some
changed attributes got overwritten before the validity checks.

https://bugzilla.redhat.com/show_bug.cgi?id=1599513

Signed-off-by: Katerina Koukiou <kkoukiou at redhat.com>
---
 src/qemu/qemu_hotplug.c | 42 +++++++++++++++++++++++++----------------
 1 file changed, 26 insertions(+), 16 deletions(-)

diff --git a/src/qemu/qemu_hotplug.c b/src/qemu/qemu_hotplug.c
index 1488f0a7c2..76ab56a479 100644
--- a/src/qemu/qemu_hotplug.c
+++ b/src/qemu/qemu_hotplug.c
@@ -3445,23 +3445,9 @@ qemuDomainChangeNet(virQEMUDriverPtr driver,
         goto cleanup;
     }
 
-    /* info: if newdev->info is empty, fill it in from olddev,
-     * otherwise verify that it matches - nothing is allowed to
-     * change. (There is no helper function to do this, so
-     * individually check the few feidls of virDomainDeviceInfo that
-     * are relevant in this case).
+    /* info: Nothing is allowed to change. First fill the missing newdev->info
+     * from olddev and then check for changes.
      */
-    if (!virDomainDeviceAddressIsValid(&newdev->info,
-                                       VIR_DOMAIN_DEVICE_ADDRESS_TYPE_PCI) &&
-        virDomainDeviceInfoCopy(&newdev->info, &olddev->info) < 0) {
-        goto cleanup;
-    }
-    if (!virPCIDeviceAddressEqual(&olddev->info.addr.pci,
-                                  &newdev->info.addr.pci)) {
-        virReportError(VIR_ERR_OPERATION_UNSUPPORTED, "%s",
-                       _("cannot modify network device guest PCI address"));
-        goto cleanup;
-    }
     /* grab alias from olddev if not set in newdev */
     if (!newdev->info.alias &&
         VIR_STRDUP(newdev->info.alias, olddev->info.alias) < 0)
@@ -3469,26 +3455,50 @@ qemuDomainChangeNet(virQEMUDriverPtr driver,
 
     /* device alias is checked already in virDomainDefCompatibleDevice */
 
+    if (newdev->info.rombar == VIR_TRISTATE_BOOL_ABSENT)
+        newdev->info.rombar = olddev->info.rombar;
     if (olddev->info.rombar != newdev->info.rombar) {
         virReportError(VIR_ERR_OPERATION_UNSUPPORTED, "%s",
                        _("cannot modify network device rom bar setting"));
         goto cleanup;
     }
+
+    if (!newdev->info.romfile &&
+        VIR_STRDUP(newdev->info.romfile, olddev->info.romfile) < 0)
+        goto cleanup;
     if (STRNEQ_NULLABLE(olddev->info.romfile, newdev->info.romfile)) {
         virReportError(VIR_ERR_OPERATION_UNSUPPORTED, "%s",
                        _("cannot modify network rom file"));
         goto cleanup;
     }
+
+    if (newdev->info.bootIndex == 0)
+        newdev->info.bootIndex = olddev->info.bootIndex;
     if (olddev->info.bootIndex != newdev->info.bootIndex) {
         virReportError(VIR_ERR_OPERATION_UNSUPPORTED, "%s",
                        _("cannot modify network device boot index setting"));
         goto cleanup;
     }
+
+    if (newdev->info.romenabled == VIR_TRISTATE_BOOL_ABSENT)
+        newdev->info.romenabled = olddev->info.romenabled;
     if (olddev->info.romenabled != newdev->info.romenabled) {
         virReportError(VIR_ERR_OPERATION_UNSUPPORTED, "%s",
                        _("cannot modify network device rom enabled setting"));
         goto cleanup;
     }
+
+    /* if pci addr is missing or is invalid we overwrite it from olddev */
+    if (!virDomainDeviceAddressIsValid(&newdev->info,
+                                       VIR_DOMAIN_DEVICE_ADDRESS_TYPE_PCI)) {
+        newdev->info.addr.pci = olddev->info.addr.pci;
+    }
+    if (!virPCIDeviceAddressEqual(&olddev->info.addr.pci,
+                                  &newdev->info.addr.pci)) {
+        virReportError(VIR_ERR_OPERATION_UNSUPPORTED, "%s",
+                       _("cannot modify network device guest PCI address"));
+        goto cleanup;
+    }
     /* (end of device info checks) */
 
     if (STRNEQ_NULLABLE(olddev->filter, newdev->filter) ||
-- 
2.17.1