submodule: reimplement with Python CFFI.

The submodule type has been implemented as a C type. When opening
a submodule's repository this leads to the bug that instead of an
actual pygit2.Repository being instantiated we only create an
object of the C Repository type.

As this is not trivially fixed within the C code, reimplement the
submodule type as a Python interface with CFFI. As submodules
provide no functionality that is usually accessed repeatedly the
code paths should not prove performance critical. In addition,
maintainability is improved by this reimplementation.

docs/submodule.rst

@@ -11,7 +11,9 @@ dedicated subdirectory of the repositories tree.
 The Submodule type
 ====================
 
+.. automethod:: pygit2.Submodule.open
+
 .. autoattribute:: pygit2.Submodule.name
 .. autoattribute:: pygit2.Submodule.path
 .. autoattribute:: pygit2.Submodule.url
-.. automethod:: pygit2.Submodule.open
+.. autoattribute:: pygit2.Submodule.branch

pygit2/decl.h

@@ -1,4 +1,5 @@
 typedef ... git_repository;
+typedef ... git_submodule;
 typedef ... git_remote;
 typedef ... git_refspec;
 typedef ... git_cred;
@@ -537,6 +538,18 @@ int git_repository_set_head(git_repository *repo, const char *refname, const git
 int git_repository_set_head_detached(git_repository *repo, const git_oid *commitish, const git_signature *signature, const char *log_message);
 int git_graph_ahead_behind(size_t *ahead, size_t *behind, git_repository *repo, const git_oid *local, const git_oid *upstream);
 
+/*
+ * git_submodule
+ */
+
+int git_submodule_lookup(git_submodule **out, git_repository *repo, char *path);
+void git_submodule_free(git_submodule *subm);
+int git_submodule_open(git_repository **out, git_submodule *subm);
+const char *git_submodule_name(git_submodule *subm);
+const char *git_submodule_path(git_submodule *subm);
+const char *git_submodule_url(git_submodule *subm);
+const char *git_submodule_branch(git_submodule *subm);
+
 /*
  * git_index
  */

pygit2/repository.py

@@ -51,6 +51,7 @@
 from .remote import RemoteCollection
 from .blame import Blame
 from .utils import to_bytes, is_string
+from .submodule import Submodule
 
 
 class Repository(_Repository):
@@ -77,6 +78,14 @@ def _common_init(self):
         ffi.buffer(repo_cptr)[:] = self._pointer[:]
         self._repo = repo_cptr[0]
 
+    def lookup_submodule(self, path):
+        csub = ffi.new('git_submodule **')
+        cpath = ffi.new('char[]', to_bytes(path))
+
+        err = C.git_submodule_lookup(csub, self._repo, cpath)
+        check_error(err)
+        return Submodule._from_c(self, csub[0])
+
     #
     # Mapping interface
     #

pygit2/submodule.py

@@ -0,0 +1,79 @@
+# -*- coding: utf-8 -*-
+#
+# Copyright 2010-2014 The pygit2 contributors
+#
+# This file is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License, version 2,
+# as published by the Free Software Foundation.
+#
+# In addition to the permissions in the GNU General Public License,
+# the authors give you unlimited permission to link the compiled
+# version of this file into combinations with other programs,
+# and to distribute those combinations without any restriction
+# coming from the use of this file.  (The General Public License
+# restrictions do apply in other respects; for example, they cover
+# modification of the file, and distribution when not linked into
+# a combined executable.)
+#
+# This file is distributed in the hope that it will be useful, but
+# WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+# General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; see the file COPYING.  If not, write to
+# the Free Software Foundation, 51 Franklin Street, Fifth Floor,
+# Boston, MA 02110-1301, USA.
+
+
+# Import from the future
+from __future__ import absolute_import, unicode_literals
+
+from .errors import check_error
+from .ffi import ffi, C
+
+class Submodule(object):
+
+    @classmethod
+    def _from_c(cls, repo, cptr):
+        subm = cls.__new__(cls)
+
+        subm._repo = repo
+        subm._subm = cptr
+
+        return subm
+
+    def __del__(self):
+        C.git_submodule_free(self._subm)
+
+    def open(self):
+        """Open the repository for a submodule."""
+        crepo = ffi.new('git_repository **')
+        err = C.git_submodule_open(crepo, self._subm)
+        check_error(err)
+
+        return self._repo._from_c(crepo[0], True)
+
+    @property
+    def name(self):
+        """Name of the submodule."""
+        name = C.git_submodule_name(self._subm)
+        return ffi.string(name).decode('utf-8')
+
+    @property
+    def path(self):
+        """Path of the submodule."""
+        path = C.git_submodule_path(self._subm)
+        return ffi.string(path).decode('utf-8')
+
+    @property
+    def url(self):
+        """URL of the submodule."""
+        url = C.git_submodule_url(self._subm)
+        return ffi.string(url).decode('utf-8')
+
+    @property
+    def branch(self):
+        """Branch that is to be tracked by the submodule."""
+        branch = C.git_submodule_branch(self._subm)
+        return ffi.string(branch).decode('utf-8')

src/pygit2.c

@@ -42,7 +42,6 @@ extern PyTypeObject RepositoryType;
 extern PyTypeObject OidType;
 extern PyTypeObject ObjectType;
 extern PyTypeObject CommitType;
-extern PyTypeObject SubmoduleType;
 extern PyTypeObject DiffType;
 extern PyTypeObject DiffIterType;
 extern PyTypeObject DiffDeltaType;
@@ -220,12 +219,6 @@ moduleinit(PyObject* m)
     ADD_CONSTANT_INT(m, GIT_FILEMODE_LINK)
     ADD_CONSTANT_INT(m, GIT_FILEMODE_COMMIT)
 
-    /*
-     * Submodules
-     */
-    INIT_TYPE(SubmoduleType, NULL, NULL);
-    ADD_TYPE(m, Submodule);
-
     /*
      * Log
      */

src/repository.c

@@ -37,7 +37,6 @@
 #include "repository.h"
 #include "branch.h"
 #include "signature.h"
-#include "submodule.h"
 #include <git2/odb_backend.h>
 
 extern PyObject *GitError;
@@ -1100,33 +1099,6 @@ Repository_listall_branches(Repository *self, PyObject *args)
     return NULL;
 }
 
-PyDoc_STRVAR(Repository_lookup_submodule__doc__,
-  "lookup_submodule(path) -> Submodule\n"
-  "\n"
-  "Lookup a submodule by its path in a repository.");
-
-PyObject *
-Repository_lookup_submodule(Repository *self, PyObject *py_path)
-{
-    git_submodule *c_submodule;
-    char *c_name;
-    int err;
-
-    c_name = py_path_to_c_str(py_path);
-    if (c_name == NULL)
-        return NULL;
-
-    err = git_submodule_lookup(&c_submodule, self->repo, c_name);
-    if (err < 0) {
-        PyObject *err_obj = Error_set_str(err, c_name);
-        free(c_name);
-        return err_obj;
-    }
-    free(c_name);
-
-    return wrap_submodule(self, c_submodule);
-}
-
 PyDoc_STRVAR(Repository_listall_submodules__doc__,
   "listall_submodules() -> [str, ...]\n"
   "\n"
@@ -1583,7 +1555,6 @@ PyMethodDef Repository_methods[] = {
     METHOD(Repository, create_reference_direct, METH_VARARGS),
     METHOD(Repository, create_reference_symbolic, METH_VARARGS),
     METHOD(Repository, listall_references, METH_NOARGS),
-    METHOD(Repository, lookup_submodule, METH_O),
     METHOD(Repository, listall_submodules, METH_NOARGS),
     METHOD(Repository, lookup_reference, METH_O),
     METHOD(Repository, revparse_single, METH_O),