add copy function

copy.go

@@ -0,0 +1,99 @@
+package goutil
+
+/*
+Copied from https://github.com/otiai10/copy and slightly altered.
+
+The MIT License (MIT)
+
+Copyright (c) 2018 otiai10
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.
+*/
+
+import (
+	"io"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+)
+
+// Copy copies src to dest, doesn't matter if src is a directory or a file
+func Copy(src, dest string) error {
+	info, err := os.Lstat(src)
+	if err != nil {
+		return err
+	}
+	return copy(src, dest, info)
+}
+
+func copy(src, dest string, info os.FileInfo) error {
+	if info.Mode()&os.ModeSymlink != 0 {
+		return linkcopy(src, dest, info)
+	}
+	if info.IsDir() {
+		return dircopy(src, dest, info)
+	}
+	return filecopy(src, dest, info)
+}
+
+func filecopy(src, dest string, info os.FileInfo) error {
+	if err := os.MkdirAll(filepath.Dir(dest), os.ModePerm); err != nil {
+		return err
+	}
+	f, err := os.Create(dest)
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+	if err = os.Chmod(f.Name(), info.Mode()); err != nil {
+		return err
+	}
+	s, err := os.Open(src)
+	if err != nil {
+		return err
+	}
+	defer s.Close()
+	_, err = io.Copy(f, s)
+	return err
+}
+
+func dircopy(srcdir, destdir string, info os.FileInfo) error {
+	if err := os.MkdirAll(destdir, info.Mode()); err != nil {
+		return err
+	}
+	contents, err := ioutil.ReadDir(srcdir)
+	if err != nil {
+		return err
+	}
+	for _, content := range contents {
+		cs, cd := filepath.Join(srcdir, content.Name()), filepath.Join(destdir, content.Name())
+		if err := copy(cs, cd, content); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func linkcopy(src, dest string, info os.FileInfo) error {
+	src, err := os.Readlink(src)
+	if err != nil {
+		return err
+	}
+	return os.Symlink(src, dest)
+}