[libvirt] [PATCHv2] snapshot: improve snapshot-list error message

[Eric Blake]

https://bugzilla.redhat.com/show_bug.cgi?id=869100 mentioned some
confusion about 'virsh snapshot-list' errors.  Clean up a
misleading error message, and add some documentation.

* tools/virsh-snapshot.c (cmdSnapshotList): Mention --current
rather than --from when appropriate.
* tools/virsh.pod (snapshot-list): Mention that the named starting
point is NOT part of the list except under --tree.
---

v2: This is my take at the problem; v1 was written by Osier:
https://www.redhat.com/archives/libvir-list/2012-October/msg01183.html

 tools/virsh-snapshot.c | 2 ++
 tools/virsh.pod        | 4 +++-
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/tools/virsh-snapshot.c b/tools/virsh-snapshot.c
index 53de2b3..1641f90 100644
--- a/tools/virsh-snapshot.c
+++ b/tools/virsh-snapshot.c
@@ -1197,6 +1197,8 @@ cmdSnapshotList(vshControl *ctl, const vshCmd *cmd)
         }
         if (from) {
             vshError(ctl, "%s",
+                     vshCommandOptBool(cmd, "current") ?
+                     _("--roots and --current are mutually exclusive") :
                      _("--roots and --from are mutually exclusive"));
             goto cleanup;
         }
diff --git a/tools/virsh.pod b/tools/virsh.pod
index 76f32c2..372c5e9 100644
--- a/tools/virsh.pod
+++ b/tools/virsh.pod
@@ -2764,7 +2764,9 @@ start at the current snapshot.  When used in isolation or with
 I<--parent>, the list is limited to direct children unless
 I<--descendants> is also present.  When used with I<--tree>, the
 use of I<--descendants> is implied.  This option is not compatible
-with I<--roots>.
+with I<--roots>.  Note that the starting point of I<--from> or
+I<--current> is not included in the list unless the I<--tree>
+option is also present.

 If I<--leaves> is specified, the list will be filtered to just
 snapshots that have no children.  Likewise, if I<--no-leaves> is
-- 
1.7.11.7