vendor: add buildkit

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

vendor/github.com/tonistiigi/fsutil/fs.go

@@ -0,0 +1,72 @@
+package fsutil
+
+import (
+	"context"
+	"io"
+	"os"
+	"path"
+	"path/filepath"
+	"strings"
+
+	"github.com/pkg/errors"
+	"github.com/tonistiigi/fsutil/types"
+)
+
+type FS interface {
+	Walk(context.Context, filepath.WalkFunc) error
+	Open(string) (io.ReadCloser, error)
+}
+
+func NewFS(root string, opt *WalkOpt) FS {
+	return &fs{
+		root: root,
+		opt:  opt,
+	}
+}
+
+type fs struct {
+	root string
+	opt  *WalkOpt
+}
+
+func (fs *fs) Walk(ctx context.Context, fn filepath.WalkFunc) error {
+	return Walk(ctx, fs.root, fs.opt, fn)
+}
+
+func (fs *fs) Open(p string) (io.ReadCloser, error) {
+	return os.Open(filepath.Join(fs.root, p))
+}
+
+func SubDirFS(fs FS, stat types.Stat) FS {
+	return &subDirFS{fs: fs, stat: stat}
+}
+
+type subDirFS struct {
+	fs   FS
+	stat types.Stat
+}
+
+func (fs *subDirFS) Walk(ctx context.Context, fn filepath.WalkFunc) error {
+	main := &StatInfo{Stat: &fs.stat}
+	if !main.IsDir() {
+		return errors.Errorf("fs subdir not mode directory")
+	}
+	if main.Name() != fs.stat.Path {
+		return errors.Errorf("subdir path must be single file")
+	}
+	if err := fn(fs.stat.Path, main, nil); err != nil {
+		return err
+	}
+	return fs.fs.Walk(ctx, func(p string, fi os.FileInfo, err error) error {
+		stat, ok := fi.Sys().(*types.Stat)
+		if !ok {
+			return errors.Wrapf(err, "invalid fileinfo without stat info: %s", p)
+		}
+		stat.Path = path.Join(fs.stat.Path, stat.Path)
+		return fn(filepath.Join(fs.stat.Path, p), &StatInfo{stat}, nil)
+	})
+}
+
+func (fs *subDirFS) Open(p string) (io.ReadCloser, error) {
+	return fs.fs.Open(strings.TrimPrefix(p, fs.stat.Path+"/"))
+}