[libvirt] [PATCH] virsh: fixed handling of targetless disks (e.g. empty CDROM) in 'domblkinfo' cmd

[Pavel Mores]

virDomainGetBlockInfo() returns error if called on a disk with no target
(a targetless disk might be a removable media drive with no media in it,
for instance an empty CDROM drive).

So far this caused the virsh domblkinfo --all command to abort and ignore
any remaining (not yet displayed) disk devices.  This patch fixes it by
ignoring virDomainGetBlockInfo() errors for CDROM and floppy drives,
similar to how it's done for network drives.

https://bugzilla.redhat.com/show_bug.cgi?id=1619625

Signed-off-by: Pavel Mores <pmores at redhat.com>
---
 tools/virsh-domain-monitor.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/tools/virsh-domain-monitor.c b/tools/virsh-domain-monitor.c
index 0e2c4191d7..0f495c1a3f 100644
--- a/tools/virsh-domain-monitor.c
+++ b/tools/virsh-domain-monitor.c
@@ -473,6 +473,7 @@ cmdDomblkinfo(vshControl *ctl, const vshCmd *cmd)
     char *cap = NULL;
     char *alloc = NULL;
     char *phy = NULL;
+    char *device_type = NULL;
     vshTablePtr table = NULL;
 
     if (!(dom = virshCommandOptDomain(ctl, cmd, NULL)))
@@ -510,6 +511,8 @@ cmdDomblkinfo(vshControl *ctl, const vshCmd *cmd)
             rc = virDomainGetBlockInfo(dom, target, &info, 0);
 
             if (rc < 0) {
+                device_type = virXPathString("string(./@device)", ctxt);
+
                 /* If protocol is present that's an indication of a networked
                  * storage device which cannot provide statistics, so generate
                  * 0 based data and get the next disk. */
@@ -518,9 +521,16 @@ cmdDomblkinfo(vshControl *ctl, const vshCmd *cmd)
                     virGetLastErrorDomain() == VIR_FROM_STORAGE) {
                     memset(&info, 0, sizeof(info));
                     vshResetLibvirtError();
+                } else if (device_type != NULL &&
+                        (STRCASEEQ(device_type, "cdrom") ||
+                        STRCASEEQ(device_type, "floppy"))) {
+                    memset(&info, 0, sizeof(info));
+                    vshResetLibvirtError();
                 } else {
                     goto cleanup;
                 }
+
+                VIR_FREE(device_type);
             }
 
             if (!cmdDomblkinfoGet(ctl, &info, &cap, &alloc, &phy, human))
@@ -556,6 +566,7 @@ cmdDomblkinfo(vshControl *ctl, const vshCmd *cmd)
     VIR_FREE(target);
     VIR_FREE(protocol);
     VIR_FREE(disks);
+    VIR_FREE(device_type);
     xmlXPathFreeContext(ctxt);
     xmlFreeDoc(xmldoc);
     return ret;
-- 
2.21.0