thodg/libgit2

diff --git a/include/git2/commit.h b/include/git2/commit.h
index e7ef518..0f76012 100644
--- a/include/git2/commit.h
+++ b/include/git2/commit.h
@@ -201,14 +201,12 @@ GIT_EXTERN(int) git_commit_nth_gen_ancestor(
 	unsigned int n);
 
 /**
- * Create a new commit in the repository using `git_object`
- * instances as parameters.
+ * Create new commit in the repository from a list of `git_object` pointers
  *
- * The message will not be cleaned up. This can be achieved
- * through `git_message_prettify()`.
+ * The message will not be cleaned up automatically. You can do that with
+ * the `git_message_prettify()` function.
  *
- * @param id Pointer where to store the OID of the
- *	newly created commit
+ * @param id Pointer in which to store the OID of the newly created commit
  *
  * @param repo Repository where to store the commit
  *
@@ -219,93 +217,69 @@ GIT_EXTERN(int) git_commit_nth_gen_ancestor(
  *	make it point to this commit. If the reference doesn't
  *	exist yet, it will be created.
  *
- * @param author Signature representing the author and the authory
- *	time of this commit
+ * @param author Signature with author and author time of commit
  *
- * @param committer Signature representing the committer and the
- * commit time of this commit
+ * @param committer Signature with committer and * commit time of commit
  *
  * @param message_encoding The encoding for the message in the
- * commit, represented with a standard encoding name.
- * E.g. "UTF-8". If NULL, no encoding header is written and
- * UTF-8 is assumed.
+ *  commit, represented with a standard encoding name.
+ *  E.g. "UTF-8". If NULL, no encoding header is written and
+ *  UTF-8 is assumed.
  *
  * @param message Full message for this commit
  *
  * @param tree An instance of a `git_tree` object that will
- * be used as the tree for the commit. This tree object must
- * also be owned by the given `repo`.
+ *  be used as the tree for the commit. This tree object must
+ *  also be owned by the given `repo`.
  *
  * @param parent_count Number of parents for this commit
  *
  * @param parents[] Array of `parent_count` pointers to `git_commit`
- * objects that will be used as the parents for this commit. This
- * array may be NULL if `parent_count` is 0 (root commit). All the
- * given commits must be owned by the `repo`.
+ *  objects that will be used as the parents for this commit. This
+ *  array may be NULL if `parent_count` is 0 (root commit). All the
+ *  given commits must be owned by the `repo`.
  *
  * @return 0 or an error code
  *	The created commit will be written to the Object Database and
  *	the given reference will be updated to point to it
  */
 GIT_EXTERN(int) git_commit_create(
-		git_oid *id,
-		git_repository *repo,
-		const char *update_ref,
-		const git_signature *author,
-		const git_signature *committer,
-		const char *message_encoding,
-		const char *message,
-		const git_tree *tree,
-		int parent_count,
-		const git_commit *parents[]);
+	git_oid *id,
+	git_repository *repo,
+	const char *update_ref,
+	const git_signature *author,
+	const git_signature *committer,
+	const char *message_encoding,
+	const char *message,
+	const git_tree *tree,
+	int parent_count,
+	const git_commit *parents[]);
 
 /**
- * Create a new commit in the repository using a variable
- * argument list.
+ * Create new commit in the repository using a variable argument list.
  *
- * The message will be cleaned up from excess whitespace
- * it will be made sure that the last line ends with a '\n'.
+ * The message will be cleaned up from excess whitespace and it will be made
+ * sure that the last line ends with a '\n'.
  *
- * The parents for the commit are specified as a variable
- * list of pointers to `const git_commit *`. Note that this
- * is a convenience method which may not be safe to export
- * for certain languages or compilers
+ * The parents for the commit are specified as a variable list of pointers
+ * to `const git_commit *`. Note that this is a convenience method which may
+ * not be safe to export for certain languages or compilers
  *
- * All other parameters remain the same
+ * All other parameters remain the same at `git_commit_create()`.
  *
  * @see git_commit_create
  */
 GIT_EXTERN(int) git_commit_create_v(
-		git_oid *id,
-		git_repository *repo,
-		const char *update_ref,
-		const git_signature *author,
-		const git_signature *committer,
-		const char *message_encoding,
-		const char *message,
-		const git_tree *tree,
-		int parent_count,
-		...);
-
-/**
- * Create a new commit in the repository, as with `git_commit_create`,
- * using `git_oid` instances as parameters instead of `git_object`.
- *
- * See documentation for `git_commit_create` for information about the
- * parameters, as the meaning is identical excepting that `tree` and
- * `parents` now take `git_oid`.
- */
-GIT_EXTERN(int) git_commit_create_oid(
-		git_oid *oid,
-		git_repository *repo,
-		const char *update_ref,
-		const git_signature *author,
-		const git_signature *committer,
-		const char *message_encoding,
-		const char *message,
-		const git_oid *tree,
-		int parent_count,
-		const git_oid *parents[]);
+	git_oid *id,
+	git_repository *repo,
+	const char *update_ref,
+	const git_signature *author,
+	const git_signature *committer,
+	const char *message_encoding,
+	const char *message,
+	const git_tree *tree,
+	int parent_count,
+	...);
 
 /** @} */
 GIT_END_DECL
diff --git a/include/git2/sys/commit.h b/include/git2/sys/commit.h
new file mode 100644
index 0000000..096e028
--- /dev/null
+++ b/include/git2/sys/commit.h
@@ -0,0 +1,45 @@
+/*
+ * 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_sys_git_commit_h__
+#define INCLUDE_sys_git_commit_h__
+
+#include "git2/common.h"
+#include "git2/types.h"
+#include "git2/oid.h"
+
+/**
+ * @file git2/sys/commit.h
+ * @brief Low-level Git commit creation
+ * @defgroup git_backend Git custom backend APIs
+ * @ingroup Git
+ * @{
+ */
+GIT_BEGIN_DECL
+
+/**
+ * Create new commit in the repository from a list of `git_oid` values
+ *
+ * See documentation for `git_commit_create()` for information about the
+ * parameters, as the meaning is identical excepting that `tree` and
+ * `parents` now take `git_oid`.  This is a dangerous API in that the
+ * `parents` list of `git_oid`s in not checked for validity.
+ */
+GIT_EXTERN(int) git_commit_create_from_oids(
+	git_oid *oid,
+	git_repository *repo,
+	const char *update_ref,
+	const git_signature *author,
+	const git_signature *committer,
+	const char *message_encoding,
+	const char *message,
+	const git_oid *tree,
+	int parent_count,
+	const git_oid *parents[]);
+
+/** @} */
+GIT_END_DECL
+#endif
diff --git a/src/commit.c b/src/commit.c
index e6bfd95..dd41692 100644
--- a/src/commit.c
+++ b/src/commit.c
@@ -9,6 +9,7 @@
 #include "git2/object.h"
 #include "git2/repository.h"
 #include "git2/signature.h"
+#include "git2/sys/commit.h"
 
 #include "common.h"
 #include "odb.h"
@@ -44,16 +45,16 @@ void git_commit__free(git_commit *commit)
 }
 
 int git_commit_create_v(
-		git_oid *oid,
-		git_repository *repo,
-		const char *update_ref,
-		const git_signature *author,
-		const git_signature *committer,
-		const char *message_encoding,
-		const char *message,
-		const git_tree *tree,
-		int parent_count,
-		...)
+	git_oid *oid,
+	git_repository *repo,
+	const char *update_ref,
+	const git_signature *author,
+	const git_signature *committer,
+	const char *message_encoding,
+	const char *message,
+	const git_tree *tree,
+	int parent_count,
+	...)
 {
 	va_list ap;
 	int i, res;
@@ -76,22 +77,25 @@ int git_commit_create_v(
 	return res;
 }
 
-int git_commit_create_oid(
-		git_oid *oid,
-		git_repository *repo,
-		const char *update_ref,
-		const git_signature *author,
-		const git_signature *committer,
-		const char *message_encoding,
-		const char *message,
-		const git_oid *tree,
-		int parent_count,
-		const git_oid *parents[])
+int git_commit_create_from_oids(
+	git_oid *oid,
+	git_repository *repo,
+	const char *update_ref,
+	const git_signature *author,
+	const git_signature *committer,
+	const char *message_encoding,
+	const char *message,
+	const git_oid *tree,
+	int parent_count,
+	const git_oid *parents[])
 {
 	git_buf commit = GIT_BUF_INIT;
 	int i;
 	git_odb *odb;
 
+	assert(oid && repo && tree && parent_count >= 0);
+	assert(git_object_owner((const git_object *)tree) == repo);
+
 	git_oid__writebuf(&commit, "tree ", tree);
 
 	for (i = 0; i < parent_count; ++i)
@@ -128,21 +132,21 @@ on_error:
 }
 
 int git_commit_create(
-		git_oid *oid,
-		git_repository *repo,
-		const char *update_ref,
-		const git_signature *author,
-		const git_signature *committer,
-		const char *message_encoding,
-		const char *message,
-		const git_tree *tree,
-		int parent_count,
-		const git_commit *parents[])
+	git_oid *oid,
+	git_repository *repo,
+	const char *update_ref,
+	const git_signature *author,
+	const git_signature *committer,
+	const char *message_encoding,
+	const char *message,
+	const git_tree *tree,
+	int parent_count,
+	const git_commit *parents[])
 {
-        int retval, i;
+	int retval, i;
 	const git_oid **parent_oids;
 
-	assert(git_object_owner((const git_object *)tree) == repo);
+	assert(parent_count >= 0);
 
 	parent_oids = git__malloc(parent_count * sizeof(git_oid *));
 	GITERR_CHECK_ALLOC(parent_oids);
@@ -152,13 +156,14 @@ int git_commit_create(
 		parent_oids[i] = git_object_id((const git_object *)parents[i]);
 	}
 
-	retval = git_commit_create_oid(oid, repo, update_ref, author, committer,
-                                       message_encoding, message,
-                                       git_object_id((const git_object *)tree),
-                                       parent_count, parent_oids);
+	retval = git_commit_create_from_oids(
+		oid, repo, update_ref, author, committer,
+		message_encoding, message,
+		git_object_id((const git_object *)tree), parent_count, parent_oids);
 
 	git__free((void *)parent_oids);
-        return retval;
+
+	return retval;
 }
 
 int git_commit__parse_buffer(git_commit *commit, const void *data, size_t len)