object-file API: split up and simplify check_object_signature()

Split up the check_object_signature() function into that non-streaming
version (it accepts an already filled "buf"), and a new
stream_object_signature() which will retrieve the object from storage,
and hash it on-the-fly.

All of the callers of check_object_signature() were effectively
calling two different functions, if we go by cyclomatic
complexity. I.e. they'd either take the early "if (map)" branch and
return early, or not. This has been the case since the "if (map)"
condition was added in 090ea12671b (parse_object: avoid putting whole
blob in core, 2012-03-07).

We can then further simplify the resulting check_object_signature()
function since only one caller wanted to pass a non-NULL "buf" and a
non-NULL "real_oidp". That "read_loose_object()" codepath used by "git
fsck" can instead use hash_object_file() followed by oideq().

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 8 insertions, 4 deletions

diff --git a/cache.h b/cache.h
index 5d08195212..c068f99c79 100644
--- a/cache.h
+++ b/cache.h
@@ -1322,15 +1322,19 @@ int parse_loose_header(const char *hdr, struct object_info *oi);
 /**
  * With in-core object data in "buf", rehash it to make sure the
  * object name actually matches "oid" to detect object corruption.
- * With "buf" == NULL, try reading the object named with "oid" using
- * the streaming interface and rehash it to do the same.
  *
  * A negative value indicates an error, usually that the OID is not
  * what we expected, but it might also indicate another error.
  */
 int check_object_signature(struct repository *r, const struct object_id *oid,
-			   void *buf, unsigned long size, const char *type,
-			   struct object_id *real_oidp);
+			   void *buf, unsigned long size, const char *type);
+
+/**
+ * A streaming version of check_object_signature().
+ * Try reading the object named with "oid" using
+ * the streaming interface and rehash it to do the same.
+ */
+int stream_object_signature(struct repository *r, const struct object_id *oid);
 
 int finalize_object_file(const char *tmpfile, const char *filename);