[ostree] static-delta: do not accept both --from=REV and --empty for generate

[Colin Walters <walters src gnome org>]

commit f2ae405f9f9658cb2252b4cbcc12f222530bcc92
Author: Giuseppe Scrivano <gscrivan redhat com>
Date:   Wed Jan 14 16:53:21 2015 +0100

    static-delta: do not accept both --from=REV and --empty for generate
    
    Signed-off-by: Giuseppe Scrivano <gscrivan redhat com>

 src/ostree/ot-builtin-static-delta.c |    6 ++++++
 tests/test-delta.sh                  |    4 ++++
 2 files changed, 10 insertions(+), 0 deletions(-)
---
diff --git a/src/ostree/ot-builtin-static-delta.c b/src/ostree/ot-builtin-static-delta.c
index 45ba6b6..b49b918 100644
--- a/src/ostree/ot-builtin-static-delta.c
+++ b/src/ostree/ot-builtin-static-delta.c
@@ -157,6 +157,12 @@ ot_static_delta_builtin_generate (int argc, char **argv, GCancellable *cancellab
 
       if (opt_empty)
         {
+          if (opt_from_rev)
+            {
+              g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_FAILED,
+                                   "Cannot specify both --empty and --from=REV");
+              goto out;
+            }
           from_source = NULL;
         }
       else if (opt_from_rev == NULL)
diff --git a/tests/test-delta.sh b/tests/test-delta.sh
index c598186..6420b21 100755
--- a/tests/test-delta.sh
+++ b/tests/test-delta.sh
@@ -68,6 +68,10 @@ ostree --repo=repo static-delta generate --from=${origrev} --to=${newrev}
 
 ostree --repo=repo static-delta list | grep ${origrev}-${newrev} || exit 1
 
+if ${CMD_PREFIX} ostree --repo=repo static-delta generate --from=${origrev} --to=${newrev} --empty 
2>>err.txt; then
+    assert_not_reached "static-delta generate --from=${origrev} --empty unexpectedly succeeded"
+fi
+
 origstart=$(echo ${origrev} | dd bs=1 count=2 2>/dev/null)
 origend=$(echo ${origrev} | dd bs=1 skip=2 2>/dev/null)
 assert_has_dir repo/deltas/${origstart}/${origend}-${newrev}