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// Copyright 2012 Jonas mg
//
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
// file, You can obtain one at http://mozilla.org/MPL/2.0/.
package file
import (
"fmt"
"io"
"io/ioutil"
"os"
"path/filepath"
)
// Copy copies file in source to file in dest preserving the mode attributes.
func Copy(source, dest string) (err error) {
// Don't backup files of backup.
if dest[len(dest)-1] != '~' {
if err = Backup(dest); err != nil {
return
}
}
srcFile, err := os.Open(source)
if err != nil {
return err
}
defer func() {
err2 := srcFile.Close()
if err2 != nil && err == nil {
err = err2
}
}()
srcInfo, err := os.Stat(source)
if err != nil {
return err
}
dstFile, err := os.OpenFile(dest, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, srcInfo.Mode().Perm())
if err != nil {
return err
}
_, err = io.Copy(dstFile, srcFile)
err2 := dstFile.Close()
if err2 != nil && err == nil {
err = err2
}
return
}
// Create creates a new file with b bytes.
func Create(filename string, b []byte) (err error) {
file, err := os.Create(filename)
if err != nil {
return err
}
_, err = file.Write(b)
err2 := file.Close()
if err2 != nil && err == nil {
err = err2
}
return
}
// CreateString is like Create, but writes the contents of string s rather than
// an array of bytes.
func CreateString(filename, s string) error {
return Create(filename, []byte(s))
}
// Overwrite truncates the named file to zero and writes len(b) bytes. It
// returns an error, if any.
func Overwrite(filename string, b []byte) (err error) {
if err := Backup(filename); err != nil {
return err
}
file, err := os.Create(filename)
if err != nil {
return err
}
_, err = file.Write(b)
err2 := file.Close()
if err2 != nil && err == nil {
err = err2
}
return
}
// OverwriteString is like Overwrite, but writes the contents of string s rather
// than an array of bytes.
func OverwriteString(filename, s string) error {
return Overwrite(filename, []byte(s))
}
// == Utility
const _BACKUP_SUFFIX = "+[1-9]~" // Suffix pattern added to backup's file name.
const PREFIX_TEMP = "test-" // Prefix to add to temporary files.
// Backup creates a backup of the named file.
//
// The schema used for the new name is: {name}\+[1-9]~
// name: The original file name.
// + : Character used to separate the file name from rest.
// number: A number from 1 to 9, using rotation.
// ~ : To indicate that it is a backup, just like it is used in Unix systems.
func Backup(filename string) error {
// Check if it is empty
info, err := os.Stat(filename)
if err != nil {
if os.IsNotExist(err) {
return nil
}
return err
}
if info.Size() == 0 {
return nil
}
files, err := filepath.Glob(filename + _BACKUP_SUFFIX)
if err != nil {
return err
}
// Number rotation
numBackup := byte(1)
if len(files) != 0 {
lastFile := files[len(files)-1]
numBackup = lastFile[len(lastFile)-2] + 1 // next number
if numBackup > '9' {
numBackup = '1'
}
} else {
numBackup = '1'
}
return Copy(filename, fmt.Sprintf("%s+%s~", filename, string(numBackup)))
}
// CopytoTemp creates a temporary file from the source file into the default
// directory for temporary files (see os.TempDir), whose name begins with prefix.
// If prefix is the empty string, uses the default value PREFIX_TEMP.
// Returns the temporary file name.
func CopytoTemp(source, prefix string) (tmpFile string, err error) {
if prefix == "" {
prefix = PREFIX_TEMP
}
src, err := os.Open(source)
if err != nil {
return "", err
}
defer func() {
err2 := src.Close()
if err2 != nil && err == nil {
err = err2
}
}()
dest, err := ioutil.TempFile("", prefix)
if err != nil {
return "", err
}
defer func() {
err2 := dest.Close()
if err2 != nil && err == nil {
err = err2
}
}()
if _, err = io.Copy(dest, src); err != nil {
return "", err
}
return dest.Name(), nil
}
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