virsh: Fix flag semantics and docs for "desc" command

This patch fixes the domain modification impact flags for tie virsh
desc command to match the new semantics and fix the docs to match
actual behavior.

tools/virsh.c

@@ -1051,7 +1051,7 @@ cmdDesc(vshControl *ctl, const vshCmd *cmd ATTRIBUTE_UNUSED)
     virDomainPtr dom;
     bool config = vshCommandOptBool(cmd, "config");
     bool live = vshCommandOptBool(cmd, "live");
-    /* current is ignored */
+    bool current = vshCommandOptBool(cmd, "current");
 
     bool title = vshCommandOptBool(cmd, "title");
     bool edit = vshCommandOptBool(cmd, "edit");
@@ -1068,6 +1068,19 @@ cmdDesc(vshControl *ctl, const vshCmd *cmd ATTRIBUTE_UNUSED)
     bool ret = false;
     unsigned int flags = VIR_DOMAIN_AFFECT_CURRENT;
 
+    if (current) {
+        if (live || config) {
+            vshError(ctl, "%s", _("--current must be specified exclusively"));
+            return false;
+        }
+        flags = VIR_DOMAIN_AFFECT_CURRENT;
+    } else {
+        if (config)
+            flags |= VIR_DOMAIN_AFFECT_CONFIG;
+        if (live)
+            flags |= VIR_DOMAIN_AFFECT_LIVE;
+    }
+
     if (!vshConnectionUsability(ctl, ctl->conn))
         return false;
 
@@ -1084,10 +1097,6 @@ cmdDesc(vshControl *ctl, const vshCmd *cmd ATTRIBUTE_UNUSED)
         virBufferAdd(&buf, opt->data, -1);
     }
 
-    if (live)
-        flags |= VIR_DOMAIN_AFFECT_LIVE;
-    if (config)
-        flags |= VIR_DOMAIN_AFFECT_CONFIG;
     if (title)
         type = VIR_DOMAIN_METADATA_TITLE;
     else
@@ -1122,7 +1131,7 @@ cmdDesc(vshControl *ctl, const vshCmd *cmd ATTRIBUTE_UNUSED)
 
             /* strip a possible newline at the end of file; some
              * editors enforce a newline, this makes editing the title
-             * more convinient */
+             * more convenient */
             if (title &&
                 (tmpstr = strrchr(desc_edited, '\n')) &&
                 *(tmpstr+1) == '\0')

tools/virsh.pod

@@ -435,20 +435,18 @@ Define a domain from an XML <file>. The domain definition is registered
 but not started.  If domain is already running, the changes will take
 effect on the next boot.
 
-=item B<desc> [I<--live> | I<--config>] [I<--title>] [I<--edit>]
-              [I<--new-desc> New description or title message]
+=item B<desc> [[I<--live>] [I<--config>] | [I<--current>]] [I<--title>]
+              [I<--edit>] [I<--new-desc> New description or title message]
 
 Show or modify description and title of a domain. These values are user
 fields that allow to store arbitrary textual data to allow easy
 identification of domains. Title should be short, although it's not enforced.
 
 Flags I<--live> or I<--config> select whether this command works on live
-or persistent definitions of the domain. By default both are influenced, while
-modifying and running definition is used while reading the note.
-
-If both I<--live> and I<--config> are specified, the I<--config> option takes
-precedence on getting the current description and both live configuration
-and config are updated while setting the description.
+or persistent definitions of the domain. If both I<--live> and I<--config>
+are specified, the I<--config> option takes precedence on getting the current
+description and both live configuration and config are updated while setting
+the description. I<--current> is exclusive and implied if none of these was specified.
 
 Flag I<--edit> specifies that an editor with the contents of current
 description or title should be opened and the contents saved back afterwards.