[PATCH 2.6/4] snapshot: virsh fallback for snapshot-list --from children

[Eric Blake <eblake@xxxxxxxxxx>]

Iterating over one level of children requires parsing all snapshots
and their parents; a bit of code shuffling makes it pretty easy
to do this as well.

* tools/virsh.c (cmdSnapshotList): Add another fallback.
---

Applies anywhere after 2.5/4, but again, easiest to test against the
same version of libvirtd if applied before 3/4.

 tools/virsh.c |   46 +++++++++++++++++++++++++++++++---------------
 1 files changed, 31 insertions(+), 15 deletions(-)

diff --git a/tools/virsh.c b/tools/virsh.c
index 93e4528..232c9b8 100644
--- a/tools/virsh.c
+++ b/tools/virsh.c
@@ -13096,6 +13096,7 @@ cmdSnapshotList(vshControl *ctl, const vshCmd *cmd)
                               information needed, 1 for parent column */
     int numsnaps;
     char **names = NULL;
+    char **parents = NULL;
     int actual = 0;
     int i;
     xmlDocPtr xml = NULL;
@@ -13112,6 +13113,7 @@ cmdSnapshotList(vshControl *ctl, const vshCmd *cmd)
     const char *from = NULL;
     virDomainSnapshotPtr start = NULL;
     bool emulate_from = false;
+    bool descendants = false;

     if (vshCommandOptString(cmd, "from", &from) < 0) {
         vshError(ctl, _("invalid from argument '%s'"), from);
@@ -13155,25 +13157,27 @@ cmdSnapshotList(vshControl *ctl, const vshCmd *cmd)
         goto cleanup;

     if (from) {
+        descendants = vshCommandOptBool(cmd, "descendants");
         start = virDomainSnapshotLookupByName(dom, from, 0);
         if (!start)
             goto cleanup;
-        if (vshCommandOptBool(cmd, "descendants") || tree) {
+        if (descendants || tree) {
             flags |= VIR_DOMAIN_SNAPSHOT_LIST_DESCENDANTS;
         }
         numsnaps = virDomainSnapshotNumChildren(start, flags);
-        /* XXX Is it worth emulating --from without --tree on older servers?  */
-        if (tree) {
-            if (numsnaps >= 0) {
-                numsnaps++;
-            } else if (last_error->code == VIR_ERR_NO_SUPPORT) {
-                /* We can emulate --tree --from.  */
+        if (numsnaps < 0) {
+            /* XXX also want to emulate --descendants without --tree */
+            if ((!descendants || tree)
+                last_error->code == VIR_ERR_NO_SUPPORT) {
+                /* We can emulate --from.  */
                 virFreeError(last_error);
                 last_error = NULL;
                 emulate_from = true;
                 flags &= ~VIR_DOMAIN_SNAPSHOT_LIST_DESCENDANTS;
                 numsnaps = virDomainSnapshotNum(dom, flags);
             }
+        } else if (tree) {
+            numsnaps++;
         }
     } else {
         numsnaps = virDomainSnapshotNum(dom, flags);
@@ -13234,9 +13238,11 @@ cmdSnapshotList(vshControl *ctl, const vshCmd *cmd)
     if (actual < 0)
         goto cleanup;

-    if (tree) {
-        char indentBuf[INDENT_BUFLEN];
-        char **parents = vshCalloc(ctl, sizeof(char *), actual);
+    if (!tree)
+        qsort(&names[0], actual, sizeof(char*), namesorter);
+
+    if (tree || emulate_from) {
+        parents = vshCalloc(ctl, sizeof(char *), actual);
         for (i = (from && !emulate_from); i < actual; i++) {
             /* free up memory from previous iterations of the loop */
             if (snapshot)
@@ -13250,6 +13256,9 @@ cmdSnapshotList(vshControl *ctl, const vshCmd *cmd)
             }
             parents[i] = vshGetSnapshotParent(ctl, snapshot);
         }
+    }
+    if (tree) {
+        char indentBuf[INDENT_BUFLEN];
         for (i = 0 ; i < actual ; i++) {
             memset(indentBuf, '\0', sizeof indentBuf);
             if (emulate_from ? STREQ(names[i], from) : !parents[i])
@@ -13263,16 +13272,19 @@ cmdSnapshotList(vshControl *ctl, const vshCmd *cmd)
                                         0,
                                         indentBuf);
         }
-        for (i = 0 ; i < actual ; i++)
-            VIR_FREE(parents[i]);
-        VIR_FREE(parents);

         ret = true;
         goto cleanup;
     } else {
-        qsort(&names[0], actual, sizeof(char*), namesorter);
+        if (emulate_from && descendants) {
+            /* XXX emulate --descendants as well */
+            goto cleanup;
+        }

         for (i = 0; i < actual; i++) {
+            if (emulate_from && STRNEQ_NULLABLE(parents[i], from))
+                continue;
+
             /* free up memory from previous iterations of the loop */
             VIR_FREE(parent);
             VIR_FREE(state);
@@ -13337,9 +13349,13 @@ cleanup:
     xmlXPathFreeContext(ctxt);
     xmlFreeDoc(xml);
     VIR_FREE(doc);
-    for (i = 0; i < actual; i++)
+    for (i = 0; i < actual; i++) {
         VIR_FREE(names[i]);
+        if (parents)
+            VIR_FREE(parents[i]);
+    }
     VIR_FREE(names);
+    VIR_FREE(parents);
     if (dom)
         virDomainFree(dom);

-- 
1.7.4.4

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