virsh: detach-disk: Add --print-xml switch

Similarly to other commands add an argument which allows to check the
XML which would be used to execute the operation instead.
Signed-off-by: NPeter Krempa <pkrempa@redhat.com>

tools/virsh-domain.c

@@ -12432,6 +12432,10 @@ static const vshCmdOptDef opts_detach_disk[] = {
     VIRSH_COMMON_OPT_DOMAIN_CONFIG,
     VIRSH_COMMON_OPT_DOMAIN_LIVE,
     VIRSH_COMMON_OPT_DOMAIN_CURRENT,
+    {.name = "print-xml",
+     .type = VSH_OT_BOOL,
+     .help = N_("print XML document rather than attach the interface")
+    },
     {.name = NULL}
 };
 
@@ -12487,6 +12491,12 @@ cmdDetachDisk(vshControl *ctl, const vshCmd *cmd)
         goto cleanup;
     }
 
+    if (vshCommandOptBool(cmd, "print-xml")) {
+        vshPrint(ctl, "%s", disk_xml);
+        functionReturn = true;
+        goto cleanup;
+    }
+
     if (flags != 0 || current)
         ret = virDomainDetachDeviceFlags(dom, disk_xml, flags);
     else

tools/virsh.pod

@@ -3113,6 +3113,7 @@ I<--persistent>.
 
 =item B<detach-disk> I<domain> I<target>
 [[[I<--live>] [I<--config>] | [I<--current>]] | [I<--persistent>]]
+[I<--print-xml>]
 
 Detach a disk device from a domain. The I<target> is the device as seen
 from the domain.
@@ -3130,6 +3131,9 @@ an offline domain, and like I<--live> I<--config> for a running domain.
 Note that older versions of virsh used I<--config> as an alias for
 I<--persistent>.
 
+If B<--print-xml> is specified, then the XML which would be used to detach the
+disk is printed instead.
+
 =item B<detach-interface> I<domain> I<type> [I<--mac mac>]
 [[[I<--live>] [I<--config>] | [I<--current>]] | [I<--persistent>]]