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// Copyright 2014 Canonical Ltd.
// Licensed under the LGPLv3, see LICENCE file for details.
package fs
import (
"fmt"
"io"
"os"
"path/filepath"
)
// Copy recursively copies the file, directory or symbolic link at src
// to dst. The destination must not exist. Symbolic links are not
// followed.
//
// If the copy fails half way through, the destination might be left
// partially written.
func Copy(src, dst string) error {
srcInfo, srcErr := os.Lstat(src)
if srcErr != nil {
return srcErr
}
_, dstErr := os.Lstat(dst)
if dstErr == nil {
// TODO(rog) add a flag to permit overwriting?
return fmt.Errorf("will not overwrite %q", dst)
}
if !os.IsNotExist(dstErr) {
return dstErr
}
switch mode := srcInfo.Mode(); mode & os.ModeType {
case os.ModeSymlink:
return copySymLink(src, dst)
case os.ModeDir:
return copyDir(src, dst, mode)
case 0:
return copyFile(src, dst, mode)
default:
return fmt.Errorf("cannot copy file with mode %v", mode)
}
}
func copySymLink(src, dst string) error {
target, err := os.Readlink(src)
if err != nil {
return err
}
return os.Symlink(target, dst)
}
func copyFile(src, dst string, mode os.FileMode) error {
srcf, err := os.Open(src)
if err != nil {
return err
}
defer srcf.Close()
dstf, err := os.OpenFile(dst, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, mode.Perm())
if err != nil {
return err
}
defer dstf.Close()
// Make the actual permissions match the source permissions
// even in the presence of umask.
if err := os.Chmod(dstf.Name(), mode.Perm()); err != nil {
return err
}
if _, err := io.Copy(dstf, srcf); err != nil {
return fmt.Errorf("cannot copy %q to %q: %v", src, dst, err)
}
return nil
}
func copyDir(src, dst string, mode os.FileMode) error {
srcf, err := os.Open(src)
if err != nil {
return err
}
defer srcf.Close()
if mode&0500 == 0 {
// The source directory doesn't have write permission,
// so give the new directory write permission anyway
// so that we have permission to create its contents.
// We'll make the permissions match at the end.
mode |= 0500
}
if err := os.Mkdir(dst, mode.Perm()); err != nil {
return err
}
for {
names, err := srcf.Readdirnames(100)
for _, name := range names {
if err := Copy(filepath.Join(src, name), filepath.Join(dst, name)); err != nil {
return err
}
}
if err == io.EOF {
break
}
if err != nil {
return fmt.Errorf("error reading directory %q: %v", src, err)
}
}
if err := os.Chmod(dst, mode.Perm()); err != nil {
return err
}
return nil
}
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