Bug 2150455

Reproduced this bug with:
libvirt-8.9.0-2.el9.x86_64


+++ This bug was initially created as a clone of Bug #2149752 +++

Description of problem:
RHV Host reports the following error for libvirtd 
-----
libvirtd[3267]: internal error: dependencies is missing or not an array
-----

This happens because of custom-ga-command guest-get-disks running periodically
libvirtd[3267]: Domain id=9 name='test' uuid=6801ef71-f7b0-4035-aac4-7ab5648f2dfd is tainted: custom-ga-command

Output for Windows VM is 
virsh -c qemu:///system qemu-agent-command test     '{ "execute": "guest-get-disks" }'
{"return":[{"name":"\\\\.\\PhysicalDrive0","partition":false,"address":{"serial":"4c19f070-34b4-46f7-af13-3488985e0582","bus-type":"sas","bus":0,"unit":0,"pci-controller":{"bus":0,"slot":8,"domain":0,"function":0},"dev":"\\\\.\\PhysicalDrive0","target":0}}]}

For Linux VM output if following
{"return":[{"name":"/dev/sda1","dependencies":["/dev/sda"],"partition":true},{"name":"/dev/sda3","dependencies":["/dev/sda"],"partition":true},{"name":"/dev/sda2","dependencies":["/dev/sda"],"partition":true},{"name":"/dev/sda","dependence


Version-Release number of selected component (if applicable):
libvirt-8.0.0-5.module+el8.6.0+14495+7194fa43.x86_64

How reproducible:
100%

Steps to Reproduce:
1. Install Windows VM with newest guest agent
2. After a few minutes internal error reported periodically  


Actual results:
Reported internal error

Expected results:
No internal error reported

Additional info:
Honestly I am not sure if this should be handled by qemu-ga-agent
virjson.c
char **
virJSONValueObjectGetStringArray(virJSONValue *object, const char *key)
{
    g_auto(GStrv) ret = NULL;
    virJSONValue *data;
    size_t n;
    size_t i;

    data = virJSONValueObjectGetArray(object, key);
    if (!data) {
        virReportError(VIR_ERR_INTERNAL_ERROR,
                       _("%s is missing or not an array"),
                       key);
        return NULL;
    }

--- Additional comment from Jiri Denemark on 2022-12-01 11:42:10 UTC ---

The reason is not the custom-ga-command as it would just return the reply
without trying to parse it. Libvirt calls guest-get-disks itself via a
supported API and fails to parse the response from Windows.

--- Additional comment from Peter Krempa on 2022-12-01 12:28:45 UTC ---

virJSONValueObjectGetStringArray originally didn't report errors but an error was added when the function was reused further, not considering the original use.

--- Additional comment from Lili Zhu on 2022-12-02 09:13:07 UTC ---

Reproduced this bug with:
libvirt-8.0.0-5.5.module+el8.6.0+16828+96e76c36.x86_64

1. prepare a win guest with guest agent device
# virsh domtime win2k19 
Time: 1669923955

2. config the libvirtd conf file
# grep -v ^# /etc/libvirt/libvirtd.conf 
log_outputs = "3:file:/var/log/libvirt/libvirtd.log"

3. restart libvirtd

4. get guest disk info
# virsh qemu-agent-command win2k19 '{ "execute": "guest-get-disks" }'
{"return":[{"name":"\\\\.\\PhysicalDrive1","partition":false,"address":{"serial":"QM00003","bus-type":"sata","bus":0,"unit":0,"pci-controller":{"bus":-1,"slot":-1,"domain":-1,"function":-1},"dev":"\\\\.\\PhysicalDrive1","target":0}},{"name":"\\\\.\\PhysicalDrive0","partition":false,"address":{"serial":"QM00001","bus-type":"sata","bus":0,"unit":0,"pci-controller":{"bus":-1,"slot":-1,"domain":-1,"function":-1},"dev":"\\\\.\\PhysicalDrive0","target":0}}]}

(There is no dependency element in win guest output)

5. check the log
# cat /var/log/libvirt/libvirtd.log 

2022-12-02 08:48:08.888+0000: 34725: error : virJSONValueObjectGetStringArray:1324 : internal error: dependencies is missing or not an array
2022-12-02 08:48:08.888+0000: 34725: error : virJSONValueObjectGetStringArray:1324 : internal error: dependencies is missing or not an array

6. prepare a rhel guest, and get the disk info
# virsh qemu-agent-command rhel8 '{ "execute": "guest-get-disks" }'
{"return":[{"name":"/dev/vda1","dependencies":["/dev/vda"],"partition":true},{"name":"/dev/vda2","dependencies":["/dev/vda"],"partition":true},{"name":"/dev/vda","dependencies":[],"partition":false,"address":{"bus-type":"virtio","bus":0,"unit":0,"pci-controller":{"bus":4,"slot":0,"domain":0,"function":0},"dev":"/dev/vda","target":0}},{"name":"/dev/dm-0","dependencies":["/dev/vda2"],"partition":false,"alias":"rhel-root"},{"name":"/dev/dm-1","dependencies":["/dev/vda2"],"partition":false,"alias":"rhel-swap"}]}

(There are dependency elements in rhel guest output)

In the function of
int qemuAgentGetDisks(qemuAgent *agent,
                      qemuAgentDiskInfo ***disks,
                      bool report_unsupported)
...
        if (virJSONValueObjectGetBoolean(entry, "partition", &disk->partition) < 0) {
            virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
                           _("'partition' missing in reply of guest-get-disks"));
            goto error;
        }

        disk->dependencies = virJSONValueObjectGetStringArray(entry, "dependencies");
        disk->alias = g_strdup(virJSONValueObjectGetString(entry, "alias"));
...

libvirt tries to parse the dependencies info no matter whether dependencies info contained in qemu agent command outputs.