[PATCH 3/6] object-name: make get_oid quietly return an error

["brian m. carlson" <sandals@xxxxxxxxxxxxxxxxxxxx>]

A reasonable person looking at the signature and usage of get_oid and
friends might conclude that in the event of an error, it always returns
-1.  However, this is not the case.  Instead, get_oid_basic dies if we
go too far back into the history of a reflog (or, when quiet, simply
exits).

This is not especially useful, since in many cases, we might want to
handle this error differently.  Let's add a flag here to make it just
return -1 like elsewhere in these code paths.

Note that we cannot make this behavior the default, since we have many
other codepaths that rely on the existing behavior, including in tests.

Signed-off-by: brian m. carlson <sandals@xxxxxxxxxxxxxxxxxxxx>
---
 cache.h       | 21 +++++++++++----------
 object-name.c |  6 +++++-
 2 files changed, 16 insertions(+), 11 deletions(-)

diff --git a/cache.h b/cache.h
index 825ec17198..416a9d9983 100644
--- a/cache.h
+++ b/cache.h
@@ -1366,16 +1366,17 @@ struct object_context {
 	char *path;
 };
 
-#define GET_OID_QUIETLY           01
-#define GET_OID_COMMIT            02
-#define GET_OID_COMMITTISH        04
-#define GET_OID_TREE             010
-#define GET_OID_TREEISH          020
-#define GET_OID_BLOB             040
-#define GET_OID_FOLLOW_SYMLINKS 0100
-#define GET_OID_RECORD_PATH     0200
-#define GET_OID_ONLY_TO_DIE    04000
-#define GET_OID_REQUIRE_PATH  010000
+#define GET_OID_QUIETLY            01
+#define GET_OID_COMMIT             02
+#define GET_OID_COMMITTISH         04
+#define GET_OID_TREE              010
+#define GET_OID_TREEISH           020
+#define GET_OID_BLOB              040
+#define GET_OID_FOLLOW_SYMLINKS  0100
+#define GET_OID_RECORD_PATH      0200
+#define GET_OID_ONLY_TO_DIE     04000
+#define GET_OID_REQUIRE_PATH   010000
+#define GET_OID_RETURN_FAILURE 020000
 
 #define GET_OID_DISAMBIGUATORS \
 	(GET_OID_COMMIT | GET_OID_COMMITTISH | \
diff --git a/object-name.c b/object-name.c
index 92862eeb1a..daa3ef77ef 100644
--- a/object-name.c
+++ b/object-name.c
@@ -911,13 +911,17 @@ static int get_oid_basic(struct repository *r, const char *str, int len,
 						len, str,
 						show_date(co_time, co_tz, DATE_MODE(RFC2822)));
 				}
-			} else {
+			} else if (!(flags & GET_OID_RETURN_FAILURE)) {
 				if (flags & GET_OID_QUIETLY) {
 					exit(128);
 				}
 				die(_("log for '%.*s' only has %d entries"),
 				    len, str, co_cnt);
 			}
+			if (flags & GET_OID_RETURN_FAILURE) {
+				free(real_ref);
+				return -1;
+			}
 		}
 	}