From cb2ed632e6c5b67e06722c79849cce05cb079950 Mon Sep 17 00:00:00 2001
From: Michal Privoznik <mprivozn@redhat.com>
Date: Tue, 15 Sep 2015 13:41:42 +0200
Subject: [PATCH] qemu_domain: Introduce qemuDomainDiskSourceDiffers

This new private API should return true iff sources of two disks
differs in sense that qemu should be instructed to change the
disk backend. For instance, ejecting a CDROM is such case, or
pointing disk into a different ISO location, and so on.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
---
 src/qemu/qemu_domain.c | 33 +++++++++++++++++++++++++++++++++
 src/qemu/qemu_domain.h |  4 ++++
 2 files changed, 37 insertions(+)

diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c
index 0ef09b2e88..bfea18b009 100644
--- a/src/qemu/qemu_domain.c
+++ b/src/qemu/qemu_domain.c
@@ -3001,6 +3001,39 @@ qemuDomainDetermineDiskChain(virQEMUDriverPtr driver,
 }
 
 
+bool
+qemuDomainDiskSourceDiffers(virConnectPtr conn,
+                            virDomainDiskDefPtr disk,
+                            virDomainDiskDefPtr origDisk)
+{
+    char *diskSrc = NULL, *origDiskSrc = NULL;
+    bool diskEmpty, origDiskEmpty;
+    bool ret = true;
+
+    diskEmpty = virStorageSourceIsEmpty(disk->src);
+    origDiskEmpty = virStorageSourceIsEmpty(origDisk->src);
+
+    if (diskEmpty && origDiskEmpty)
+        return false;
+
+    if (diskEmpty ^ origDiskEmpty)
+        return true;
+
+    if (qemuGetDriveSourceString(disk->src, conn, &diskSrc) < 0 ||
+        qemuGetDriveSourceString(origDisk->src, conn, &origDiskSrc) < 0)
+        goto cleanup;
+
+    /* So far in qemu disk sources are considered different
+     * if either path to disk or its format changes. */
+    ret = virDomainDiskGetFormat(disk) != virDomainDiskGetFormat(origDisk) ||
+          STRNEQ_NULLABLE(diskSrc, origDiskSrc);
+ cleanup:
+    VIR_FREE(diskSrc);
+    VIR_FREE(origDiskSrc);
+    return ret;
+}
+
+
 bool
 qemuDomainDiskBlockJobIsActive(virDomainDiskDefPtr disk)
 {
diff --git a/src/qemu/qemu_domain.h b/src/qemu/qemu_domain.h
index 91eaea174b..0b9fd1c14c 100644
--- a/src/qemu/qemu_domain.h
+++ b/src/qemu/qemu_domain.h
@@ -411,6 +411,10 @@ int qemuDomainDetermineDiskChain(virQEMUDriverPtr driver,
                                  bool force_probe,
                                  bool report_broken);
 
+bool qemuDomainDiskSourceDiffers(virConnectPtr conn,
+                                 virDomainDiskDefPtr disk,
+                                 virDomainDiskDefPtr origDisk);
+
 int qemuDomainStorageFileInit(virQEMUDriverPtr driver,
                               virDomainObjPtr vm,
                               virStorageSourcePtr src);
-- 
2.39.5