Move mvdan.cc/sh to v3

vendor/mvdan.cc/sh/v3/interp/perm_unix.go

@@ -0,0 +1,49 @@
+// Copyright (c) 2017, Andrey Nering <andrey.nering@gmail.com>
+// See LICENSE for licensing information
+
+// +build !windows
+
+package interp
+
+import (
+	"os"
+	"os/user"
+	"strconv"
+	"syscall"
+)
+
+// hasPermissionToDir returns if the OS current user has execute permission
+// to the given directory
+func hasPermissionToDir(info os.FileInfo) bool {
+	user, err := user.Current()
+	if err != nil {
+		return true
+	}
+	uid, _ := strconv.Atoi(user.Uid)
+	// super-user
+	if uid == 0 {
+		return true
+	}
+
+	st, _ := info.Sys().(*syscall.Stat_t)
+	if st == nil {
+		return true
+	}
+	perm := info.Mode().Perm()
+	// user (u)
+	if perm&0100 != 0 && st.Uid == uint32(uid) {
+		return true
+	}
+
+	gid, _ := strconv.Atoi(user.Gid)
+	// other users in group (g)
+	if perm&0010 != 0 && st.Uid != uint32(uid) && st.Gid == uint32(gid) {
+		return true
+	}
+	// remaining users (o)
+	if perm&0001 != 0 && st.Uid != uint32(uid) && st.Gid != uint32(gid) {
+		return true
+	}
+
+	return false
+}