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// Copyright 2014 Cloudbase Solutions SRL
// Licensed under the LGPLv3, see LICENCE file for details.
package symlink
import (
"fmt"
"os"
"path/filepath"
"github.com/juju/utils"
)
// Replace will do an atomic replacement of a symlink to a new path
func Replace(link, newpath string) error {
dstDir := filepath.Dir(link)
uuid, err := utils.NewUUID()
if err != nil {
return err
}
randStr := uuid.String()
tmpFile := filepath.Join(dstDir, "tmpfile"+randStr)
// Create the new symlink before removing the old one. This way, if New()
// fails, we still have a link to the old tools.
err = New(newpath, tmpFile)
if err != nil {
return fmt.Errorf("cannot create symlink: %s", err)
}
// On Windows, symlinks may not be overwritten. We remove it first,
// and then rename tmpFile
if _, err := os.Stat(link); err == nil {
err = os.RemoveAll(link)
if err != nil {
return err
}
}
err = os.Rename(tmpFile, link)
if err != nil {
return fmt.Errorf("cannot update tools symlink: %v", err)
}
return nil
}
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