read-cache.c: fix writing "link" index ext with null base oid

diff --git a/read-cache.c b/read-cache.c
index 7b1354d7590a70ecbd6e508bdd95eafd4793efcc..d140b44f8f29adb90c2bbcb74e6f55b06a9dcb47 100644 (file)
--- a/read-cache.c
+++ b/read-cache.c
@@ -337,7 +337,7 @@ static int is_racy_stat(const struct index_state *istate,
                );
 }
 
-static int is_racy_timestamp(const struct index_state *istate,
+int is_racy_timestamp(const struct index_state *istate,
                             const struct cache_entry *ce)
 {
        return (!S_ISGITLINK(ce->ce_mode) &&
@@ -2520,7 +2520,8 @@ static int do_write_index(struct index_state *istate, struct tempfile *tempfile,
                return err;
 
        /* Write extension data here */
-       if (!strip_extensions && istate->split_index) {
+       if (!strip_extensions && istate->split_index &&
+           !is_null_oid(&istate->split_index->base_oid)) {
                struct strbuf sb = STRBUF_INIT;
 
                err = write_link_extension(&sb, istate) < 0 ||
@@ -2794,7 +2795,7 @@ int write_locked_index(struct index_state *istate, struct lock_file *lock,
        ret = write_split_index(istate, lock, flags);
 
        /* Freshen the shared index only if the split-index was written */
-       if (!ret && !new_shared_index) {
+       if (!ret && !new_shared_index && !is_null_oid(&si->base_oid)) {
                const char *shared_index = git_path("sharedindex.%s",
                                                    oid_to_hex(&si->base_oid));
                freshen_shared_index(shared_index, 1);