repository: Change ownership semantics

The ownership semantics have been changed all over the library to be
consistent. There are no more "borrowed" or duplicated references.

Main changes:

	- `git_repository_open2` and `3` have been dropped.

	- Added setters and getters to hotswap all the repository owned
	objects:

		`git_repository_index`
		`git_repository_set_index`
		`git_repository_odb`
		`git_repository_set_odb`
		`git_repository_config`
		`git_repository_set_config`
		`git_repository_workdir`
		`git_repository_set_workdir`

	Now working directories/index files/ODBs and so on can be
	hot-swapped after creating a repository and between operations.

	- All these objects now have proper ownership semantics with
	refcounting: they all require freeing after they are no longer
	needed (the repository always keeps its internal reference).

	- Repository open and initialization has been updated to keep in
	mind the configuration files. Bare repositories are now always
	detected, and a default config file is created on init.

	- All the tests affected by these changes have been dropped from the
	old test suite and ported to the new one.

1 files changed, 17 insertions, 6 deletions

diff --git a/src/object.c b/src/object.c
index c84e94b05..12947f035 100644
--- a/src/object.c
+++ b/src/object.c
@@ -77,9 +77,15 @@ static int create_object(git_object **object_out, git_otype type)
 	return GIT_SUCCESS;
 }
 
-int git_object_lookup_prefix(git_object **object_out, git_repository *repo, const git_oid *id, unsigned int len, git_otype type)
+int git_object_lookup_prefix(
+	git_object **object_out,
+	git_repository *repo,
+	const git_oid *id,
+	unsigned int len,
+	git_otype type)
 {
 	git_object *object = NULL;
+	git_odb *odb = NULL;
 	git_odb_object *odb_obj;
 	int error = GIT_SUCCESS;
 
@@ -89,6 +95,10 @@ int git_object_lookup_prefix(git_object **object_out, git_repository *repo, cons
 		return git__throw(GIT_EAMBIGUOUSOIDPREFIX,
 			"Failed to lookup object. Prefix length is lower than %d.", GIT_OID_MINPREFIXLEN);
 
+	error = git_repository_odb__weakptr(&odb, repo);
+	if (error < GIT_SUCCESS)
+		return error;
+
 	if (len > GIT_OID_HEXSZ)
 		len = GIT_OID_HEXSZ;
 
@@ -98,10 +108,11 @@ int git_object_lookup_prefix(git_object **object_out, git_repository *repo, cons
 		 */
 		object = git_cache_get(&repo->objects, id);
 		if (object != NULL) {
-			if (type != GIT_OBJ_ANY && type != object->type)
-			{
+			if (type != GIT_OBJ_ANY && type != object->type) {
 				git_object_close(object);
-				return git__throw(GIT_EINVALIDTYPE, "Failed to lookup object. The given type does not match the type on the ODB");
+				return git__throw(GIT_EINVALIDTYPE,
+					"Failed to lookup object. "
+					"The given type does not match the type on the ODB");
 			}
 
 			*object_out = object;
@@ -113,7 +124,7 @@ int git_object_lookup_prefix(git_object **object_out, git_repository *repo, cons
 		 * it is the same cost for packed and loose object backends,
 		 * but it may be much more costly for sqlite and hiredis.
 		 */
-		error = git_odb_read(&odb_obj, repo->db, id);
+		error = git_odb_read(&odb_obj, odb, id);
 	} else {
 		git_oid short_oid;
 
@@ -133,7 +144,7 @@ int git_object_lookup_prefix(git_object **object_out, git_repository *repo, cons
 		 * - We never explore the cache, go right to exploring the backends
 		 * We chose the latter : we explore directly the backends.
 		 */
-		error = git_odb_read_prefix(&odb_obj, repo->db, &short_oid, len);
+		error = git_odb_read_prefix(&odb_obj, odb, &short_oid, len);
 	}
 
 	if (error < GIT_SUCCESS)