lib/pull: Honor require-static-deltas for scratch deltas

If a scratch delta exists and the caller has required static deltas, use
it instead of the heuristic about existing commits.

src/libostree/ostree-repo-pull.c

@@ -2690,12 +2690,14 @@ get_best_static_delta_start_for (OtPullData         *pull_data,
       memcpy (out_result->from_revision, newest_candidate, OSTREE_SHA256_STRING_LEN+1);
     }
 
-  /* If a from-scratch delta is available, we don’t want to use it if the ref
-   * or any of its ancestors already exists locally and is not partial. In
-   * that case only some of the objects in the new commit may be needed, so
-   * doing an object pull is likely more bandwidth efficient.
+  /* If a from-scratch delta is available and deltas aren't required, we don’t
+   * want to use it if the ref or any of its ancestors already exists locally
+   * and is not partial. In that case only some of the objects in the new
+   * commit may be needed, so doing an object pull is likely more bandwidth
+   * efficient.
    */
-  if (out_result->result == DELTA_SEARCH_RESULT_SCRATCH)
+  if (out_result->result == DELTA_SEARCH_RESULT_SCRATCH &&
+      !pull_data->require_static_deltas)
     {
       g_autofree char *rev = g_strdup (cur_revision);
 

tests/pull-test.sh

@@ -54,7 +54,7 @@ function verify_initial_contents() {
     assert_file_has_content baz/cow '^moo$'
 }
 
-num_tests=38
+num_tests=39
 # 3 tests needs GPG support
 num_gpg_tests=3
 if has_gpgme; then
@@ -705,5 +705,15 @@ ${CMD_PREFIX} ostree --repo=repo pull origin scratch@${rev2}
 ${CMD_PREFIX} ostree --repo=repo pull origin scratch
 echo "ok scratch delta (normal parent)"
 
+# Pull with a normal parent but require static deltas. This should fail
+# because it tries to pull the scratch delta.
+repo_init --no-gpg-verify
+${CMD_PREFIX} ostree --repo=repo pull origin scratch@${rev2}
+if ${CMD_PREFIX} ostree --repo=repo pull --require-static-deltas origin scratch 2>err.txt; then
+    assert_not_reached "pull of corrupt scratch delta unexpectedly succeeded"
+fi
+assert_file_has_content err.txt "Invalid checksum for static delta"
+echo "ok scratch delta (require static deltas with normal parent)"
+
 # Clean up the deltas so we don't leave a corrupt one around
 rm ostree-srv/gnomerepo/deltas -rf