[PATCH v2 1/4] object-name: make get_oid quietly return an error

["brian m. carlson" <sandals@crustytoothpaste.net>]

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@crustytoothpaste.net>
---
 cache.h       | 1 +
 object-name.c | 6 +++++-
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/cache.h b/cache.h
index 825ec17198..657e3ff17f 100644
--- a/cache.h
+++ b/cache.h
@@ -1376,6 +1376,7 @@ struct object_context {
 #define GET_OID_RECORD_PATH     0200
 #define GET_OID_ONLY_TO_DIE    04000
 #define GET_OID_REQUIRE_PATH  010000
+#define GET_OID_GENTLY        020000
 
 #define GET_OID_DISAMBIGUATORS \
 	(GET_OID_COMMIT | GET_OID_COMMITTISH | \
diff --git a/object-name.c b/object-name.c
index 92862eeb1a..46dbfe36a6 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_GENTLY)) {
 				if (flags & GET_OID_QUIETLY) {
 					exit(128);
 				}
 				die(_("log for '%.*s' only has %d entries"),
 				    len, str, co_cnt);
 			}
+			if (flags & GET_OID_GENTLY) {
+				free(real_ref);
+				return -1;
+			}
 		}
 	}