3 changed files with 215 additions and 4 deletions
--- a/indexer.go
+++ b/indexer.go
@ -0,0 +1,92 @@
+package git
+
+/*
+#include <git2.h>
+
+extern const git_oid * git_indexer_hash(const git_indexer *idx);
+extern int git_indexer_append(git_indexer *idx, const void *data, size_t size, git_transfer_progress *stats);
+extern int git_indexer_commit(git_indexer *idx, git_transfer_progress *stats);
+extern int _go_git_indexer_new(git_indexer **out, const char *path, unsigned int mode, git_odb *odb, void *progress_cb_payload);
+extern void git_indexer_free(git_indexer *idx);
+*/
+import "C"
+import (
+	"reflect"
+	"runtime"
+	"unsafe"
+)
+
+// Indexer can post-process packfiles and create an .idx file for efficient
+// lookup.
+type Indexer struct {
+	ptr             *C.git_indexer
+	stats           C.git_transfer_progress
+	callbacks       RemoteCallbacks
+	callbacksHandle unsafe.Pointer
+}
+
+// NewIndexer creates a new indexer instance.
+func NewIndexer(packfilePath string, odb *Odb, callback TransferProgressCallback) (indexer *Indexer, err error) {
+	indexer = new(Indexer)
+
+	runtime.LockOSThread()
+	defer runtime.UnlockOSThread()
+
+	var odbPtr *C.git_odb = nil
+	if odb != nil {
+		odbPtr = odb.ptr
+	}
+
+	indexer.callbacks.TransferProgressCallback = callback
+	indexer.callbacksHandle = pointerHandles.Track(&indexer.callbacks)
+
+	ret := C._go_git_indexer_new(&indexer.ptr, C.CString(packfilePath), 0, odbPtr, indexer.callbacksHandle)
+	if ret < 0 {
+		pointerHandles.Untrack(indexer.callbacksHandle)
+		return nil, MakeGitError(ret)
+	}
+
+	runtime.SetFinalizer(indexer, (*Indexer).Free)
+	return indexer, nil
+}
+
+// Write adds data to the indexer.
+func (indexer *Indexer) Write(data []byte) (int, error) {
+	header := (*reflect.SliceHeader)(unsafe.Pointer(&data))
+	ptr := unsafe.Pointer(header.Data)
+	size := C.size_t(header.Len)
+
+	runtime.LockOSThread()
+	defer runtime.UnlockOSThread()
+
+	ret := C.git_indexer_append(indexer.ptr, ptr, size, &indexer.stats)
+	if ret < 0 {
+		return 0, MakeGitError(ret)
+	}
+
+	return len(data), nil
+}
+
+// Commit finalizes the pack and index. It resolves any pending deltas and
+// writes out the index file.
+//
+// It also returns the packfile's hash. A packfile's name is derived from the
+// sorted hashing of all object names.
+func (indexer *Indexer) Commit() (*Oid, error) {
+	runtime.LockOSThread()
+	defer runtime.UnlockOSThread()
+
+	ret := C.git_indexer_commit(indexer.ptr, &indexer.stats)
+	if ret < 0 {
+		return nil, MakeGitError(ret)
+	}
+
+	return newOidFromC(C.git_indexer_hash(indexer.ptr)), nil
+}
+
+// Free frees the indexer and its resources.
+func (indexer *Indexer) Free() {
+	pointerHandles.Untrack(indexer.callbacksHandle)
+	runtime.SetFinalizer(indexer, nil)
+	C.git_indexer_free(indexer.ptr)
+}
--- a/odb.go
+++ b/odb.go
@ -3,8 +3,13 @@ package git
 /*
 #include <git2.h>

+extern int git_odb_backend_one_pack(git_odb_backend **out, const char *index_file);
 extern int _go_git_odb_foreach(git_odb *db, void *payload);
 extern void _go_git_odb_backend_free(git_odb_backend *backend);
+extern int _go_git_odb_write_pack(git_odb_writepack **out, git_odb *db, void *progress_payload);
+extern int _go_git_odb_writepack_append(git_odb_writepack *writepack, const void *, size_t, git_transfer_progress *);
+extern int _go_git_odb_writepack_commit(git_odb_writepack *writepack, git_transfer_progress *);
+extern void _go_git_odb_writepack_free(git_odb_writepack *writepack);
 */
 import "C"
 import (
@ -41,8 +46,19 @@ func NewOdbBackendFromC(ptr *C.git_odb_backend) (backend *OdbBackend) {
 	return backend
 }

-func (v *Odb) AddBackend(backend *OdbBackend, priority int) (err error) {
+func (v *Odb) AddAlternate(backend *OdbBackend, priority int) (err error) {
+	runtime.LockOSThread()
+	defer runtime.UnlockOSThread()

+	ret := C.git_odb_add_alternate(v.ptr, backend.ptr, C.int(priority))
+	if ret < 0 {
+		backend.Free()
+		return MakeGitError(ret)
+	}
+	return nil
+}
+
+func (v *Odb) AddBackend(backend *OdbBackend, priority int) (err error) {
 	runtime.LockOSThread()
 	defer runtime.UnlockOSThread()

@ -54,6 +70,18 @@ func (v *Odb) AddBackend(backend *OdbBackend, priority int) (err error) {
 	return nil
 }

+func NewOdbBackendOnePack(packfileIndexPath string) (backend *OdbBackend, err error) {
+	runtime.LockOSThread()
+	defer runtime.UnlockOSThread()
+
+	var odbOnePack *C.git_odb_backend = nil
+	ret := C.git_odb_backend_one_pack(&odbOnePack, C.CString(packfileIndexPath))
+	if ret < 0 {
+		return nil, MakeGitError(ret)
+	}
+	return NewOdbBackendFromC(odbOnePack), nil
+}
+
 func (v *Odb) ReadHeader(oid *Oid) (uint64, ObjectType, error) {
 	runtime.LockOSThread()
 	defer runtime.UnlockOSThread()
@ -205,6 +233,30 @@ func (v *Odb) NewWriteStream(size int64, otype ObjectType) (*OdbWriteStream, err
 	return stream, nil
 }

+// NewWritePack opens a stream for writing a pack file to the ODB. If the ODB
+// layer understands pack files, then the given packfile will likely be
+// streamed directly to disk (and a corresponding index created). If the ODB
+// layer does not understand pack files, the objects will be stored in whatever
+// format the ODB layer uses.
+func (v *Odb) NewWritePack(callback TransferProgressCallback) (*OdbWritepack, error) {
+	writepack := new(OdbWritepack)
+
+	runtime.LockOSThread()
+	defer runtime.UnlockOSThread()
+
+	writepack.callbacks.TransferProgressCallback = callback
+	writepack.callbacksHandle = pointerHandles.Track(&writepack.callbacks)
+
+	ret := C._go_git_odb_write_pack(&writepack.ptr, v.ptr, writepack.callbacksHandle)
+	if ret < 0 {
+		pointerHandles.Untrack(writepack.callbacksHandle)
+		return nil, MakeGitError(ret)
+	}
+
+	runtime.SetFinalizer(writepack, (*OdbWritepack).Free)
+	return writepack, nil
+}
+
 func (v *OdbBackend) Free() {
 	C._go_git_odb_backend_free(v.ptr)
 }
@ -318,3 +370,45 @@ func (stream *OdbWriteStream) Free() {
 	runtime.SetFinalizer(stream, nil)
 	C.git_odb_stream_free(stream.ptr)
 }
+
+// OdbWritepack is a stream to write a packfile to the ODB.
+type OdbWritepack struct {
+	ptr             *C.git_odb_writepack
+	stats           C.git_transfer_progress
+	callbacks       RemoteCallbacks
+	callbacksHandle unsafe.Pointer
+}
+
+func (writepack *OdbWritepack) Write(data []byte) (int, error) {
+	header := (*reflect.SliceHeader)(unsafe.Pointer(&data))
+	ptr := unsafe.Pointer(header.Data)
+	size := C.size_t(header.Len)
+
+	runtime.LockOSThread()
+	defer runtime.UnlockOSThread()
+
+	ret := C._go_git_odb_writepack_append(writepack.ptr, ptr, size, &writepack.stats)
+	if ret < 0 {
+		return 0, MakeGitError(ret)
+	}
+
+	return len(data), nil
+}
+
+func (writepack *OdbWritepack) Commit() error {
+	runtime.LockOSThread()
+	defer runtime.UnlockOSThread()
+
+	ret := C._go_git_odb_writepack_commit(writepack.ptr, &writepack.stats)
+	if ret < 0 {
+		return MakeGitError(ret)
+	}
+
+	return nil
+}
+
+func (writepack *OdbWritepack) Free() {
+	pointerHandles.Untrack(writepack.callbacksHandle)
+	runtime.SetFinalizer(writepack, nil)
+	C._go_git_odb_writepack_free(writepack.ptr)
+}
--- a/wrapper.c
+++ b/wrapper.c
@ -174,4 +174,29 @@ void _go_git_writestream_free(git_writestream *stream)
 	stream->free(stream);
 }

+int _go_git_odb_write_pack(git_odb_writepack **out, git_odb *db, void *progress_payload)
+{
+	return git_odb_write_pack(out, db, (git_transfer_progress_cb)transferProgressCallback, progress_payload);
+}
+
+int _go_git_odb_writepack_append(git_odb_writepack *writepack, const void *data, size_t size, git_transfer_progress *stats)
+{
+	return writepack->append(writepack, data, size, stats);
+}
+
+int _go_git_odb_writepack_commit(git_odb_writepack *writepack, git_transfer_progress *stats)
+{
+	return writepack->commit(writepack, stats);
+}
+
+void _go_git_odb_writepack_free(git_odb_writepack *writepack)
+{
+	writepack->free(writepack);
+}
+
+int _go_git_indexer_new(git_indexer **out, const char *path, unsigned int mode, git_odb *odb, void *progress_cb_payload)
+{
+	return git_indexer_new(out, path, mode, odb, (git_transfer_progress_cb)transferProgressCallback, progress_cb_payload);
+}
+
 /* EOF */