vendor: add buildkit

Signed-off-by: Tonis Tiigi <tonistiigi@gmail.com>

vendor/github.com/containerd/continuity/driver/utils.go

@@ -0,0 +1,90 @@
+/*
+   Copyright The containerd Authors.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package driver
+
+import (
+	"io"
+	"io/ioutil"
+	"os"
+	"sort"
+)
+
+// ReadFile works the same as ioutil.ReadFile with the Driver abstraction
+func ReadFile(r Driver, filename string) ([]byte, error) {
+	f, err := r.Open(filename)
+	if err != nil {
+		return nil, err
+	}
+	defer f.Close()
+
+	data, err := ioutil.ReadAll(f)
+	if err != nil {
+		return nil, err
+	}
+
+	return data, nil
+}
+
+// WriteFile works the same as ioutil.WriteFile with the Driver abstraction
+func WriteFile(r Driver, filename string, data []byte, perm os.FileMode) error {
+	f, err := r.OpenFile(filename, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, perm)
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+
+	n, err := f.Write(data)
+	if err != nil {
+		return err
+	} else if n != len(data) {
+		return io.ErrShortWrite
+	}
+
+	return nil
+}
+
+// ReadDir works the same as ioutil.ReadDir with the Driver abstraction
+func ReadDir(r Driver, dirname string) ([]os.FileInfo, error) {
+	f, err := r.Open(dirname)
+	if err != nil {
+		return nil, err
+	}
+	defer f.Close()
+
+	dirs, err := f.Readdir(-1)
+	if err != nil {
+		return nil, err
+	}
+
+	sort.Sort(fileInfos(dirs))
+	return dirs, nil
+}
+
+// Simple implementation of the sort.Interface for os.FileInfo
+type fileInfos []os.FileInfo
+
+func (fis fileInfos) Len() int {
+	return len(fis)
+}
+
+func (fis fileInfos) Less(i, j int) bool {
+	return fis[i].Name() < fis[j].Name()
+}
+
+func (fis fileInfos) Swap(i, j int) {
+	fis[i], fis[j] = fis[j], fis[i]
+}