3 files changed, 105 insertions, 0 deletions
diff --git a/index.go b/index.go
new file mode 100644
index 0000000..72b1d5b
--- /dev/null
+++ b/index.go
@@ -0,0 +1,49 @@
+package git
+
+/*
+#cgo pkg-config: libgit2
+#include <git2.h>
+#include <git2/errors.h>
+*/
+import "C"
+import (
+	"runtime"
+	"unsafe"
+)
+
+type Index struct {
+	ptr *C.git_index
+}
+
+func newIndexFromC(ptr *C.git_index) *Index {
+	idx := &Index{ptr}
+	runtime.SetFinalizer(idx, (*Index).Free)
+	return idx
+}
+
+func (v *Index) AddByPath(path string) error {
+	cstr := C.CString(path)
+	defer C.free(unsafe.Pointer(cstr))
+
+	ret := C.git_index_add_bypath(v.ptr, cstr)
+	if ret < 0 {
+		return LastError()
+	}
+
+	return nil
+}
+
+func (v *Index) WriteTree() (*Oid, error) {
+	oid := new(Oid)
+	ret := C.git_index_write_tree(oid.toC(), v.ptr)
+	if ret < 0 {
+		return nil, LastError()
+	}
+
+	return oid, nil
+}
+
+func (v *Index) Free() {
+	runtime.SetFinalizer(v, nil)
+	C.git_index_free(v.ptr)
+}
diff --git a/index_test.go b/index_test.go
new file mode 100644
index 0000000..b853ebf
--- /dev/null
+++ b/index_test.go
@@ -0,0 +1,46 @@
+package git
+
+import (
+	"os"
+	"runtime"
+	"testing"
+	"io/ioutil"
+)
+
+func TestCreateRepoAndStage(t *testing.T) {
+	// figure out where we can create the test repo
+	path, err := ioutil.TempDir("", "git2go")
+	checkFatal(t, err)
+	repo, err := Init(path, false)
+	checkFatal(t, err)
+
+	tmpfile := "README"
+	err = ioutil.WriteFile(path + "/" + tmpfile, []byte("foo\n"), 0644)
+	checkFatal(t, err)
+	defer os.RemoveAll(path)
+
+	idx, err := repo.Index()
+	checkFatal(t, err)
+	err = idx.AddByPath(tmpfile)
+	checkFatal(t, err)
+	treeId, err := idx.WriteTree()
+	checkFatal(t, err)
+
+	if treeId.String() != "b7119b11e8ef7a1a5a34d3ac87f5b075228ac81e" {
+		t.Fatalf("%v", treeId.String())
+	}
+}
+
+func checkFatal(t *testing.T, err error) {
+	if err == nil {
+		return
+	}
+
+	// The failure happens at wherever we were called, not here
+	_, file, line, ok := runtime.Caller(1)
+	if !ok {
+		t.Fatal()
+	}
+
+	t.Fatalf("Fail at %v:%v", file, line)
+}
diff --git a/repository.go b/repository.go
index bfbfebd..5313af3 100644
--- a/repository.go
+++ b/repository.go
@@ -62,6 +62,16 @@ func (v *Repository) Config() (*Config, error) {
 	return config, nil
 }
 
+func (v *Repository) Index() (*Index, error) {
+	var ptr *C.git_index
+	ret := C.git_repository_index(&ptr, v.ptr)
+	if ret < 0 {
+		return nil, LastError()
+	}
+
+	return newIndexFromC(ptr), nil
+}
+
 func (v *Repository) LookupTree(oid *Oid) (*Tree, error) {
 	tree := new(Tree)
 	ret := C.git_tree_lookup(&tree.ptr, v.ptr, oid.toC())