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gocsaf/cmd/csaf_aggregator/lazytransaction.go
2022-08-02 21:52:02 +02:00

95 lines
1.8 KiB
Go

// This file is Free Software under the MIT License
// without warranty, see README.md and LICENSES/MIT.txt for details.
//
// SPDX-License-Identifier: MIT
//
// SPDX-FileCopyrightText: 2022 German Federal Office for Information Security (BSI) <https://www.bsi.bund.de>
// Software-Engineering: 2022 Intevation GmbH <https://intevation.de>
package main
import (
"log"
"os"
"path/filepath"
"github.com/csaf-poc/csaf_distribution/util"
)
type lazyTransaction struct {
src string
dstDir string
dst string
}
func newLazyTransaction(src, dstDir string) *lazyTransaction {
return &lazyTransaction{
src: src,
dstDir: dstDir,
}
}
func (lt *lazyTransaction) Src() string {
return lt.src
}
func (lt *lazyTransaction) Dst() (string, error) {
if lt.dst != "" {
return lt.dst, nil
}
srcBase := filepath.Base(lt.src)
folder := filepath.Join(lt.dstDir, srcBase)
dst, err := util.MakeUniqDir(folder)
if err != nil {
return "", err
}
// Copy old content into new.
if err := util.DeepCopy(dst, lt.src); err != nil {
os.RemoveAll(dst)
return "", err
}
lt.dst = dst
return dst, nil
}
func (lt *lazyTransaction) rollback() error {
if lt.dst == "" {
return nil
}
err := os.RemoveAll(lt.dst)
lt.dst = ""
return err
}
func (lt *lazyTransaction) commit() error {
if lt.dst == "" {
return nil
}
defer func() { lt.dst = "" }()
// The expanded path of the original link.
orig, err := filepath.EvalSymlinks(lt.src)
if err != nil {
os.RemoveAll(lt.dst)
return err
}
// Switch directories.
symlink := filepath.Join(lt.dst, filepath.Base(lt.src))
if err := os.Symlink(lt.dst, symlink); err != nil {
os.RemoveAll(lt.dst)
return err
}
log.Printf("Move %q -> %q\n", symlink, lt.src)
if err := os.Rename(symlink, lt.src); err != nil {
os.RemoveAll(lt.dst)
return err
}
return os.RemoveAll(orig)
}