/
main.go
96 lines (81 loc) 路 1.76 KB
/
main.go
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// Copyright 2019 Changkun Ou. All rights reserved.
// Use of this source code is governed by a MIT
// license that can be found in the LICENSE file.
// inspiring from https://www.youtube.com/watch?v=1B71SL6Y0kA
package main
import (
"fmt"
"io"
"os"
)
// CopyFile : General Approach
func CopyFile(src, dst string) error {
r, err := os.Open(src)
if err != nil {
return fmt.Errorf("copy %s %s: %v", src, dst, err)
}
defer r.Close()
w, err := os.Create(dst)
if err != nil {
return fmt.Errorf("copy %s %s: %v", src, dst, err)
}
if _, err := io.Copy(w, r); err != nil {
w.Close()
os.Remove(dst)
return fmt.Errorf("copy %s %s: %v", src, dst, err)
}
if err := w.Close(); err != nil {
os.Remove(dst)
return fmt.Errorf("copy %s %s: %v", src, dst, err)
}
return nil
}
// SafeCopyFile : Error handling by abstraction
func SafeCopyFile(src, dst string) error {
c := safeOpen(src)
c.Create(dst)
c.Copy()
c.Close()
if c.err != nil {
os.Remove(dst)
return fmt.Errorf("copy %s %s: %v", src, dst, c.err)
}
return nil
}
type SafeCopy struct {
r, w *os.File
src, dst string
err error
}
func safeOpen(src string) SafeCopy {
r, err := os.Open(src)
return SafeCopy{r: r, src: src, err: err}
}
func (c *SafeCopy) Create(dst string) {
c.dst = dst
if c.err != nil {
c.err = fmt.Errorf("copy %s %s: %v", c.src, c.dst, c.err)
return
}
c.w, c.err = os.Create(c.dst)
}
func (c *SafeCopy) Copy() {
if c.err != nil {
c.r.Close()
c.err = fmt.Errorf("copy %s %s: %v", c.src, c.dst, c.err)
return
}
_, c.err = io.Copy(c.r, c.w)
}
func (c *SafeCopy) Close() {
if c.err != nil {
if c.w != nil {
c.w.Close()
os.Remove(c.dst)
}
c.err = fmt.Errorf("copy %s %s: %v", c.src, c.dst, c.err)
return
}
c.err = c.r.Close()
c.err = c.w.Close()
}