[libvirt] [PATCH v3] storage: netfs and iscsi need option srcSpec for resource discovery

[Guannan Ren]

The option 'srcSpec' to virsh command find-storage-pool-sources
is optional for logical type of storage pool, but mandatory for
netfs and iscsi type.
When missing the option for netfs and iscsi, libvirt reports XML
parsing error due to null string option srcSpec.

error: Failed to find any netfs pool sources
error: (storage_source_specification):1: Document is empty
(null)

error: Failed to find any netfs pool sources
error: internal error pool type 'netfs' requires option \
       --srcSpec for source discovery
---
 src/remote/remote_driver.c   |   14 +-------------
 src/storage/storage_driver.c |    8 ++++++++
 2 files changed, 9 insertions(+), 13 deletions(-)

diff --git a/src/remote/remote_driver.c b/src/remote/remote_driver.c
index acae5d0..5f8d378 100644
--- a/src/remote/remote_driver.c
+++ b/src/remote/remote_driver.c
@@ -2621,23 +2621,11 @@ remoteFindStoragePoolSources (virConnectPtr conn,
     remote_find_storage_pool_sources_args args;
     remote_find_storage_pool_sources_ret ret;
     struct private_data *priv = conn->storagePrivateData;
-    const char *emptyString = "";
 
     remoteDriverLock(priv);
 
     args.type = (char*)type;
-    /*
-     * I'd think the following would work here:
-     *    args.srcSpec = (char**)&srcSpec;
-     * since srcSpec is a remote_string (not a remote_nonnull_string).
-     *
-     * But when srcSpec is NULL, this yields:
-     *    libvir: Remote error : marshaling args
-     *
-     * So for now I'm working around this by turning NULL srcSpecs
-     * into empty strings.
-     */
-    args.srcSpec = srcSpec ? (char **)&srcSpec : (char **)&emptyString;
+    args.srcSpec = srcSpec ? (char **)&srcSpec : NULL;
     args.flags = flags;
 
     memset (&ret, 0, sizeof(ret));
diff --git a/src/storage/storage_driver.c b/src/storage/storage_driver.c
index c9b8021..3d491eb 100644
--- a/src/storage/storage_driver.c
+++ b/src/storage/storage_driver.c
@@ -458,6 +458,14 @@ storageFindPoolSources(virConnectPtr conn,
         goto cleanup;
     }
 
+    if ((!srcSpec) && (backend_type == VIR_STORAGE_POOL_ISCSI ||
+                       backend_type == VIR_STORAGE_POOL_NETFS)) {
+        virReportError(VIR_ERR_INTERNAL_ERROR,
+                       _("pool type '%s' requires option --srcSpec "
+                         "for source discovery"), type);
+        goto cleanup;
+    }
+
     ret = backend->findPoolSources(conn, srcSpec, flags);
 
 cleanup:
-- 
1.7.7.5