cp.go

/*
Copyright (c) 2015 Caleb Spare

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.
*/

// Package cp offers simple file and directory copying for Go.
package main

import (
	"errors"
	"io"
	"os"
	"path/filepath"
	"strings"
)

var errCopyFileWithDir = errors.New("dir argument to CopyFile")

// CopyFile copies the file with path src to dst. The new file must not exist.
// It is created with the same permissions as src.
func CopyFile(dst, src string) error {
	rf, err := os.Open(src)
	if err != nil {
		return err
	}
	defer rf.Close()
	rstat, err := rf.Stat()
	if err != nil {
		return err
	}
	if rstat.IsDir() {
		return errCopyFileWithDir
	}

	wf, err := os.OpenFile(dst, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, rstat.Mode())
	if err != nil {
		return err
	}
	if _, err := io.Copy(wf, rf); err != nil {
		wf.Close()
		return err
	}
	return wf.Close()
}

// CopyAll copies the file or (recursively) the directory at src to dst.
// Permissions are preserved. dst must not already exist.
func CopyAll(dst, src string) error {
	Log.Info("copy recursive", "dst", dst, "src", src)
	return filepath.Walk(src, makeWalkFn(dst, src))
}

func makeWalkFn(dst, src string) filepath.WalkFunc {
	return func(path string, info os.FileInfo, err error) error {
		if err != nil {
			return err
		}
		dstPath := filepath.Join(dst, strings.TrimPrefix(path, src))
		if info.IsDir() {
			err := os.Mkdir(dstPath, info.Mode())
			if err == nil || os.IsExist(err) {
				return nil
			}
			return err
		}
		return CopyFile(dstPath, path)
	}
}