+/**
+ * Do the three-way merge using fake ancestor, his tree constructed
+ * from the fake ancestor and the postimage of the patch, and our
+ * state.
+ */
+static int run_fallback_merge_recursive(const struct am_state *state,
+ unsigned char *orig_tree,
+ unsigned char *our_tree,
+ unsigned char *his_tree)
+{
+ struct child_process cp = CHILD_PROCESS_INIT;
+ int status;
+
+ cp.git_cmd = 1;
+
+ argv_array_pushf(&cp.env_array, "GITHEAD_%s=%.*s",
+ sha1_to_hex(his_tree), linelen(state->msg), state->msg);
+ if (state->quiet)
+ argv_array_push(&cp.env_array, "GIT_MERGE_VERBOSITY=0");
+
+ argv_array_push(&cp.args, "merge-recursive");
+ argv_array_push(&cp.args, sha1_to_hex(orig_tree));
+ argv_array_push(&cp.args, "--");
+ argv_array_push(&cp.args, sha1_to_hex(our_tree));
+ argv_array_push(&cp.args, sha1_to_hex(his_tree));
+
+ status = run_command(&cp) ? (-1) : 0;
+ discard_cache();
+ read_cache();
+ return status;
+}
+