hash: require hash algorithm in `is_empty_{blob,tree}_oid()`

Both functions `is_empty_{blob,tree}_oid()` use `the_repository` to
derive the hash function that shall be used. Require callers to pass in
the hash algorithm to get rid of this implicit dependency.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/fast-import.c

@@ -2361,7 +2361,9 @@ static void file_change_m(const char *p, struct branch *b)
 	parse_path_eol(&path, p, "path");
 
 	/* Git does not track empty, non-toplevel directories. */
-	if (S_ISDIR(mode) && is_empty_tree_oid(&oid) && *path.buf) {
+	if (S_ISDIR(mode) &&
+	    is_empty_tree_oid(&oid, the_repository->hash_algo) &&
+	    *path.buf) {
 		tree_content_remove(&b->branch_tree, path.buf, NULL, 0);
 		return;
 	}

cache-tree.c

@@ -422,7 +422,7 @@ static int update_one(struct cache_tree *it,
 		/*
 		 * "sub" can be an empty tree if all subentries are i-t-a.
 		 */
-		if (contains_ita && is_empty_tree_oid(oid))
+		if (contains_ita && is_empty_tree_oid(oid, the_repository->hash_algo))
 			continue;
 
 		strbuf_grow(&buffer, entlen + 100);

diffcore-rename.c

@@ -1422,7 +1422,7 @@ void diffcore_rename_extended(struct diff_options *options,
 				 strcmp(options->single_follow, p->two->path))
 				continue; /* not interested */
 			else if (!options->flags.rename_empty &&
-				 is_empty_blob_oid(&p->two->oid))
+				 is_empty_blob_oid(&p->two->oid, the_repository->hash_algo))
 				continue;
 			else if (add_rename_dst(p) < 0) {
 				warning("skipping rename detection, detected"
@@ -1432,7 +1432,7 @@ void diffcore_rename_extended(struct diff_options *options,
 			}
 		}
 		else if (!options->flags.rename_empty &&
-			 is_empty_blob_oid(&p->one->oid))
+			 is_empty_blob_oid(&p->one->oid, the_repository->hash_algo))
 			continue;
 		else if (!DIFF_PAIR_UNMERGED(p) && !DIFF_FILE_VALID(p->two)) {
 			/*

hash-ll.h

@@ -350,4 +350,16 @@ static inline int is_null_oid(const struct object_id *oid)
 const char *empty_tree_oid_hex(void);
 const char *empty_blob_oid_hex(void);
 
+static inline int is_empty_blob_oid(const struct object_id *oid,
+				    const struct git_hash_algo *algop)
+{
+	return oideq(oid, algop->empty_blob);
+}
+
+static inline int is_empty_tree_oid(const struct object_id *oid,
+				    const struct git_hash_algo *algop)
+{
+	return oideq(oid, algop->empty_tree);
+}
+
 #endif

hash.h

@@ -6,14 +6,4 @@
 
 #define the_hash_algo the_repository->hash_algo
 
-static inline int is_empty_blob_oid(const struct object_id *oid)
-{
-	return oideq(oid, the_hash_algo->empty_blob);
-}
-
-static inline int is_empty_tree_oid(const struct object_id *oid)
-{
-	return oideq(oid, the_hash_algo->empty_tree);
-}
-
 #endif

read-cache.c

@@ -337,7 +337,7 @@ static int ce_match_stat_basic(const struct cache_entry *ce, struct stat *st)
 
 	/* Racily smudged entry? */
 	if (!ce->ce_stat_data.sd_size) {
-		if (!is_empty_blob_oid(&ce->oid))
+		if (!is_empty_blob_oid(&ce->oid, the_repository->hash_algo))
 			changed |= DATA_CHANGED;
 	}