vendor: add buildkit

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

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

@@ -0,0 +1,52 @@
+// +build !windows
+
+package fsutil
+
+import (
+	"os"
+	"syscall"
+
+	"github.com/containerd/continuity/sysx"
+	"github.com/pkg/errors"
+	"github.com/tonistiigi/fsutil/types"
+)
+
+func rewriteMetadata(p string, stat *types.Stat) error {
+	for key, value := range stat.Xattrs {
+		sysx.Setxattr(p, key, value, 0)
+	}
+
+	if err := os.Lchown(p, int(stat.Uid), int(stat.Gid)); err != nil {
+		return errors.Wrapf(err, "failed to lchown %s", p)
+	}
+
+	if os.FileMode(stat.Mode)&os.ModeSymlink == 0 {
+		if err := os.Chmod(p, os.FileMode(stat.Mode)); err != nil {
+			return errors.Wrapf(err, "failed to chown %s", p)
+		}
+	}
+
+	if err := chtimes(p, stat.ModTime); err != nil {
+		return errors.Wrapf(err, "failed to chtimes %s", p)
+	}
+
+	return nil
+}
+
+// handleTarTypeBlockCharFifo is an OS-specific helper function used by
+// createTarFile to handle the following types of header: Block; Char; Fifo
+func handleTarTypeBlockCharFifo(path string, stat *types.Stat) error {
+	mode := uint32(stat.Mode & 07777)
+	if os.FileMode(stat.Mode)&os.ModeCharDevice != 0 {
+		mode |= syscall.S_IFCHR
+	} else if os.FileMode(stat.Mode)&os.ModeNamedPipe != 0 {
+		mode |= syscall.S_IFIFO
+	} else {
+		mode |= syscall.S_IFBLK
+	}
+
+	if err := syscall.Mknod(path, mode, int(mkdev(stat.Devmajor, stat.Devminor))); err != nil {
+		return err
+	}
+	return nil
+}