2022-11-17 14:28:33 +03:00
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// License: GPLv3 Copyright: 2022, Kovid Goyal, <kovid at kovidgoyal.net>
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package utils
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import (
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2023-02-15 08:16:47 +03:00
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"errors"
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"fmt"
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"io"
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"io/fs"
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"os"
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"path/filepath"
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)
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var _ = fmt.Print
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2023-02-21 13:05:41 +03:00
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func AtomicCreateSymlink(oldname, newname string) (err error) {
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err = os.Symlink(oldname, newname)
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if err == nil {
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return nil
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}
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if !errors.Is(err, fs.ErrExist) {
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return err
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}
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2023-02-22 04:45:18 +03:00
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if et, err := os.Readlink(newname); err == nil && et == oldname {
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return nil
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}
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for {
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tempname := newname + RandomFilename()
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err = os.Symlink(oldname, tempname)
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if err == nil {
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err = os.Rename(tempname, newname)
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if err != nil {
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os.Remove(tempname)
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}
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return err
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}
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if !errors.Is(err, fs.ErrExist) {
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return err
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}
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}
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}
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2024-07-22 12:31:19 +03:00
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func AtomicWriteFile(path string, data io.Reader, perm os.FileMode) (err error) {
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npath, err := filepath.EvalSymlinks(path)
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if errors.Is(err, fs.ErrNotExist) {
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err = nil
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npath = path
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}
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if err == nil {
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path = npath
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path, err = filepath.Abs(path)
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if err == nil {
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var f *os.File
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f, err = os.CreateTemp(filepath.Dir(path), filepath.Base(path)+".atomic-write-")
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if err == nil {
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removed := false
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defer func() {
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f.Close()
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if !removed {
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os.Remove(f.Name())
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removed = true
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}
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}()
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if _, err = io.Copy(f, data); err == nil {
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if err = f.Chmod(perm); err == nil {
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if err = f.Sync(); err == nil { // Sync before rename to ensure we dont end up with a zero sized file
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if err = os.Rename(f.Name(), path); err == nil {
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removed = true
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}
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}
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}
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}
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}
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}
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}
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return
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}
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2024-07-22 12:31:19 +03:00
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func AtomicUpdateFile(path string, data io.Reader, perms ...fs.FileMode) (err error) {
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perm := fs.FileMode(0o644)
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if len(perms) > 0 {
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perm = perms[0]
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}
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s, err := os.Stat(path)
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if err == nil {
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perm = s.Mode().Perm()
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}
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return AtomicWriteFile(path, data, perm)
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}
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