[libvirt] [PATCH] virsh: improve doMigrate function docs

[ajia at redhat.com]

From: Alex Jia <ajia at redhat.com>

When running virsh migrate with --xml option and actual xml file doesn't
exist, virsh hasn't output any error information, although return value
is 1.

* tools/virsh.c: Raising a appropriate error information when operation fails.

* How to reproduce?
% virsh migrate <domain> --live qemu+ssh://<target host>/system --xml non-existent.xml
% echo $? 

* Fixed result:
error: file 'non-existent.xml' doesn't exist

Signed-off-by: Alex Jia <ajia at redhat.com>
---
 tools/virsh.c |    5 +++--
 1 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/tools/virsh.c b/tools/virsh.c
index e4b812e..020e7b5 100644
--- a/tools/virsh.c
+++ b/tools/virsh.c
@@ -6338,9 +6338,10 @@ doMigrate (void *opaque)
         flags |= VIR_MIGRATE_CHANGE_PROTECTION;
 
     if (xmlfile &&
-        virFileReadAll(xmlfile, 8192, &xml) < 0)
+        virFileReadAll(xmlfile, 8192, &xml) < 0) {
+        vshError(ctl, _("file '%s' doesn't exist"), xmlfile);
         goto out;
-
+    }
 
     if ((flags & VIR_MIGRATE_PEER2PEER) ||
         vshCommandOptBool (cmd, "direct")) {
-- 
1.7.1