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f4da995940
The intent of atomicfile is to overwrite regular files. Most use cases that would overwrite irregular files, unix sockets, named pipes, devices, and so on are more than likely misuse, so disallow them. Fixes #7658 Signed-off-by: James Tucker <james@tailscale.com>
52 lines
1.3 KiB
Go
52 lines
1.3 KiB
Go
// Copyright (c) Tailscale Inc & AUTHORS
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// SPDX-License-Identifier: BSD-3-Clause
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// Package atomicfile contains code related to writing to filesystems
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// atomically.
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//
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// This package should be considered internal; its API is not stable.
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package atomicfile // import "tailscale.com/atomicfile"
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import (
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"fmt"
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"os"
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"path/filepath"
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"runtime"
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)
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// WriteFile writes data to filename+some suffix, then renames it into filename.
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// The perm argument is ignored on Windows. If the target filename already
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// exists but is not a regular file, WriteFile returns an error.
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func WriteFile(filename string, data []byte, perm os.FileMode) (err error) {
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fi, err := os.Stat(filename)
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if err == nil && !fi.Mode().IsRegular() {
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return fmt.Errorf("%s already exists and is not a regular file", filename)
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}
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f, err := os.CreateTemp(filepath.Dir(filename), filepath.Base(filename)+".tmp")
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if err != nil {
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return err
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}
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tmpName := f.Name()
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defer func() {
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if err != nil {
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f.Close()
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os.Remove(tmpName)
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}
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}()
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if _, err := f.Write(data); err != nil {
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return err
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}
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if runtime.GOOS != "windows" {
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if err := f.Chmod(perm); err != nil {
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return err
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}
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}
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if err := f.Sync(); err != nil {
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return err
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}
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if err := f.Close(); err != nil {
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return err
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}
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return os.Rename(tmpName, filename)
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}
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