thodg/libgit2

diff --git a/include/git2/config.h b/include/git2/config.h
index 19d4cb7..5a2f956 100644
--- a/include/git2/config.h
+++ b/include/git2/config.h
@@ -43,29 +43,6 @@ typedef struct {
 
 typedef int  (*git_config_foreach_cb)(const git_config_entry *, void *);
 
-
-/**
- * Generic backend that implements the interface to
- * access a configuration file
- */
-struct git_config_backend {
-	unsigned int version;
-	struct git_config *cfg;
-
-	/* Open means open the file/database and parse if necessary */
-	int (*open)(struct git_config_backend *, unsigned int level);
-	int (*get)(const struct git_config_backend *, const char *key, const git_config_entry **entry);
-	int (*get_multivar)(struct git_config_backend *, const char *key, const char *regexp, git_config_foreach_cb callback, void *payload);
-	int (*set)(struct git_config_backend *, const char *key, const char *value);
-	int (*set_multivar)(git_config_backend *cfg, const char *name, const char *regexp, const char *value);
-	int (*del)(struct git_config_backend *, const char *key);
-	int (*foreach)(struct git_config_backend *, const char *, git_config_foreach_cb callback, void *payload);
-	int (*refresh)(struct git_config_backend *);
-	void (*free)(struct git_config_backend *);
-};
-#define GIT_CONFIG_BACKEND_VERSION 1
-#define GIT_CONFIG_BACKEND_INIT {GIT_CONFIG_BACKEND_VERSION}
-
 typedef enum {
 	GIT_CVAR_FALSE = 0,
 	GIT_CVAR_TRUE = 1,
@@ -154,30 +131,6 @@ GIT_EXTERN(int) git_config_open_default(git_config **out);
 GIT_EXTERN(int) git_config_new(git_config **out);
 
 /**
- * Add a generic config file instance to an existing config
- *
- * Note that the configuration object will free the file
- * automatically.
- *
- * Further queries on this config object will access each
- * of the config file instances in order (instances with
- * a higher priority level will be accessed first).
- *
- * @param cfg the configuration to add the file to
- * @param file the configuration file (backend) to add
- * @param level the priority level of the backend
- * @param force if a config file already exists for the given
- *  priority level, replace it
- * @return 0 on success, GIT_EEXISTS when adding more than one file
- *  for a given priority level (and force_replace set to 0), or error code
- */
-GIT_EXTERN(int) git_config_add_backend(
-	git_config *cfg,
-	git_config_backend *file,
-	unsigned int level,
-	int force);
-
-/**
  * Add an on-disk config file instance to an existing config
  *
  * The on-disk file pointed at by `path` will be opened and
@@ -192,10 +145,9 @@ GIT_EXTERN(int) git_config_add_backend(
  * a higher priority level will be accessed first).
  *
  * @param cfg the configuration to add the file to
- * @param path path to the configuration file (backend) to add
+ * @param path path to the configuration file to add
  * @param level the priority level of the backend
- * @param force if a config file already exists for the given
- *  priority level, replace it
+ * @param force replace config file at the given priority level
  * @return 0 on success, GIT_EEXISTS when adding more than one file
  *  for a given priority level (and force_replace set to 0),
  *  GIT_ENOTFOUND when the file doesn't exist or error code
diff --git a/include/git2/sys/config.h b/include/git2/sys/config.h
new file mode 100644
index 0000000..c9039e9
--- /dev/null
+++ b/include/git2/sys/config.h
@@ -0,0 +1,70 @@
+/*
+ * Copyright (C) the libgit2 contributors. All rights reserved.
+ *
+ * This file is part of libgit2, distributed under the GNU GPL v2 with
+ * a Linking Exception. For full terms see the included COPYING file.
+ */
+#ifndef INCLUDE_git_sys_config_h__
+#define INCLUDE_git_sys_config_h__
+
+#include "git2/common.h"
+#include "git2/types.h"
+#include "git2/config.h"
+
+/**
+ * @file git2/sys/config.h
+ * @brief Git config backend routines
+ * @ingroup Git
+ * @{
+ */
+GIT_BEGIN_DECL
+
+/**
+ * Generic backend that implements the interface to
+ * access a configuration file
+ */
+struct git_config_backend {
+	unsigned int version;
+	struct git_config *cfg;
+
+	/* Open means open the file/database and parse if necessary */
+	int (*open)(struct git_config_backend *, unsigned int level);
+	int (*get)(const struct git_config_backend *, const char *key, const git_config_entry **entry);
+	int (*get_multivar)(struct git_config_backend *, const char *key, const char *regexp, git_config_foreach_cb callback, void *payload);
+	int (*set)(struct git_config_backend *, const char *key, const char *value);
+	int (*set_multivar)(git_config_backend *cfg, const char *name, const char *regexp, const char *value);
+	int (*del)(struct git_config_backend *, const char *key);
+	int (*foreach)(struct git_config_backend *, const char *, git_config_foreach_cb callback, void *payload);
+	int (*refresh)(struct git_config_backend *);
+	void (*free)(struct git_config_backend *);
+};
+#define GIT_CONFIG_BACKEND_VERSION 1
+#define GIT_CONFIG_BACKEND_INIT {GIT_CONFIG_BACKEND_VERSION}
+
+/**
+ * Add a generic config file instance to an existing config
+ *
+ * Note that the configuration object will free the file
+ * automatically.
+ *
+ * Further queries on this config object will access each
+ * of the config file instances in order (instances with
+ * a higher priority level will be accessed first).
+ *
+ * @param cfg the configuration to add the file to
+ * @param file the configuration file (backend) to add
+ * @param level the priority level of the backend
+ * @param force if a config file already exists for the given
+ *  priority level, replace it
+ * @return 0 on success, GIT_EEXISTS when adding more than one file
+ *  for a given priority level (and force_replace set to 0), or error code
+ */
+GIT_EXTERN(int) git_config_add_backend(
+	git_config *cfg,
+	git_config_backend *file,
+	unsigned int level,
+	int force);
+
+/** @} */
+GIT_END_DECL
+#endif
diff --git a/src/config.c b/src/config.c
index 5379b0e..1283522 100644
--- a/src/config.c
+++ b/src/config.c
@@ -9,6 +9,7 @@
 #include "fileops.h"
 #include "config.h"
 #include "git2/config.h"
+#include "git2/sys/config.h"
 #include "vector.h"
 #include "buf_text.h"
 #include "config_file.h"
diff --git a/src/config_file.c b/src/config_file.c
index 8b51ab2..a4ff8bb 100644
--- a/src/config_file.c
+++ b/src/config_file.c
@@ -12,6 +12,7 @@
 #include "buffer.h"
 #include "buf_text.h"
 #include "git2/config.h"
+#include "git2/sys/config.h"
 #include "git2/types.h"
 #include "strmap.h"
 
diff --git a/src/submodule.c b/src/submodule.c
index 2fdaf2f..0a22e3b 100644
--- a/src/submodule.c
+++ b/src/submodule.c
@@ -7,6 +7,7 @@
 
 #include "common.h"
 #include "git2/config.h"
+#include "git2/sys/config.h"
 #include "git2/types.h"
 #include "git2/repository.h"
 #include "git2/index.h"
diff --git a/tests-clar/config/backend.c b/tests-clar/config/backend.c
index 28502a8..3fd6eb1 100644
--- a/tests-clar/config/backend.c
+++ b/tests-clar/config/backend.c
@@ -1,4 +1,5 @@
 #include "clar_libgit2.h"
+#include "git2/sys/config.h"
 
 void test_config_backend__checks_version(void)
 {