Merge branch 'jt/index-fd-wo-repo-regression-fix-maint'

During Git 2.52 timeframe, we broke streaming computation of object
hash outside a repository, which has been corrected.

* jt/index-fd-wo-repo-regression-fix-maint:
  object-file: avoid ODB transaction when not writing objects

object-file.c

@@ -1642,6 +1642,34 @@ static int index_blob_packfile_transaction(struct odb_transaction_files *transac
 	return 0;
 }
 
+static int hash_blob_stream(const struct git_hash_algo *hash_algo,
+			    struct object_id *result_oid, int fd, size_t size)
+{
+	unsigned char buf[16384];
+	struct git_hash_ctx ctx;
+	unsigned header_len;
+
+	header_len = format_object_header((char *)buf, sizeof(buf),
+					  OBJ_BLOB, size);
+	hash_algo->init_fn(&ctx);
+	git_hash_update(&ctx, buf, header_len);
+
+	while (size) {
+		size_t rsize = size < sizeof(buf) ? size : sizeof(buf);
+		ssize_t read_result = read_in_full(fd, buf, rsize);
+
+		if ((read_result < 0) || ((size_t)read_result != rsize))
+			return -1;
+
+		git_hash_update(&ctx, buf, rsize);
+		size -= read_result;
+	}
+
+	git_hash_final_oid(result_oid, &ctx);
+
+	return 0;
+}
+
 int index_fd(struct index_state *istate, struct object_id *oid,
 	     int fd, struct stat *st,
 	     enum object_type type, const char *path, unsigned flags)
@@ -1663,6 +1691,7 @@ int index_fd(struct index_state *istate, struct object_id *oid,
 		ret = index_core(istate, oid, fd, xsize_t(st->st_size),
 				 type, path, flags);
 	} else {
+		if (flags & INDEX_WRITE_OBJECT) {
 			struct object_database *odb = the_repository->objects;
 			struct odb_transaction_files *files_transaction;
 			struct odb_transaction *transaction;
@@ -1675,6 +1704,10 @@ int index_fd(struct index_state *istate, struct object_id *oid,
 							      xsize_t(st->st_size),
 							      path, flags);
 			odb_transaction_commit(transaction);
+		} else {
+			ret = hash_blob_stream(the_repository->hash_algo, oid,
+					       fd, xsize_t(st->st_size));
+		}
 	}
 
 	close(fd);

t/t1517-outside-repo.sh

@@ -93,6 +93,14 @@ test_expect_success 'diff outside repository' '
 	test_cmp expect actual
 '
 
+test_expect_success 'hash object exceeding bigFileThreshold outside repository' '
+	(
+		cd non-repo &&
+		echo foo >foo &&
+		git -c core.bigFileThreshold=1 hash-object --stdin <foo
+	)
+'
+
 test_expect_success 'stripspace outside repository' '
 	nongit git stripspace -s </dev/null
 '