cephfs: add Directory type and funcs to open and close it

Add the Directory type and the OpenDir function to get an open
Directory and a Close function to close/free it.

Signed-off-by: John Mulligan <jmulligan@redhat.com>

cephfs/directory.go

@@ -0,0 +1,49 @@
+package cephfs
+
+/*
+#cgo LDFLAGS: -lcephfs
+#cgo CPPFLAGS: -D_FILE_OFFSET_BITS=64
+#include <stdlib.h>
+#include <dirent.h>
+#include <cephfs/libcephfs.h>
+*/
+import "C"
+
+import (
+	"unsafe"
+)
+
+// Directory represents an open directory handle.
+type Directory struct {
+	mount *MountInfo
+	dir   *C.struct_ceph_dir_result
+}
+
+// OpenDir returns a new Directory handle open for I/O.
+//
+// Implements:
+//  int ceph_opendir(struct ceph_mount_info *cmount, const char *name, struct ceph_dir_result **dirpp);
+func (mount *MountInfo) OpenDir(path string) (*Directory, error) {
+	var dir *C.struct_ceph_dir_result
+
+	cPath := C.CString(path)
+	defer C.free(unsafe.Pointer(cPath))
+
+	ret := C.ceph_opendir(mount.mount, cPath, &dir)
+	if ret != 0 {
+		return nil, getError(ret)
+	}
+
+	return &Directory{
+		mount: mount,
+		dir:   dir,
+	}, nil
+}
+
+// Close the open directory handle.
+//
+// Implements:
+//  int ceph_closedir(struct ceph_mount_info *cmount, struct ceph_dir_result *dirp);
+func (dir *Directory) Close() error {
+	return getError(C.ceph_closedir(dir.mount.mount, dir.dir))
+}

cephfs/directory_test.go

@@ -0,0 +1,38 @@
+package cephfs
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestOpenCloseDir(t *testing.T) {
+	mount := fsConnect(t)
+	defer fsDisconnect(t, mount)
+
+	dir1 := "/base"
+	err := mount.MakeDir(dir1, 0755)
+	assert.NoError(t, err)
+	defer func() { assert.NoError(t, mount.RemoveDir(dir1)) }()
+
+	dir2 := dir1 + "/a"
+	err = mount.MakeDir(dir2, 0755)
+	assert.NoError(t, err)
+	defer func() { assert.NoError(t, mount.RemoveDir(dir2)) }()
+
+	dir, err := mount.OpenDir(dir1)
+	assert.NoError(t, err)
+	assert.NotNil(t, dir)
+	err = dir.Close()
+	assert.NoError(t, err)
+
+	dir, err = mount.OpenDir(dir2)
+	assert.NoError(t, err)
+	assert.NotNil(t, dir)
+	err = dir.Close()
+	assert.NoError(t, err)
+
+	dir, err = mount.OpenDir("/no.such.dir")
+	assert.Error(t, err)
+	assert.Nil(t, dir)
+}