59 lines
1.6 KiB
Go
59 lines
1.6 KiB
Go
// Copyright (c) Tailscale Inc & AUTHORS
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// SPDX-License-Identifier: BSD-3-Clause
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package paths
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import (
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"os"
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"path/filepath"
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"tailscale.com/types/logger"
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)
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// TryConfigFileMigration carefully copies the contents of oldFile to
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// newFile, returning the path which should be used to read the config.
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// - if newFile already exists, don't modify it just return its path
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// - if neither oldFile nor newFile exist, return newFile for a fresh
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// default config to be written to.
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// - if oldFile exists but copying to newFile fails, return oldFile so
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// there will at least be some config to work with.
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func TryConfigFileMigration(logf logger.Logf, oldFile, newFile string) string {
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_, err := os.Stat(newFile)
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if err == nil {
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// Common case for a system which has already been migrated.
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return newFile
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}
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if !os.IsNotExist(err) {
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logf("TryConfigFileMigration failed; new file: %v", err)
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return newFile
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}
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contents, err := os.ReadFile(oldFile)
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if err != nil {
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// Common case for a new user.
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return newFile
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}
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if err = MkStateDir(filepath.Dir(newFile)); err != nil {
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logf("TryConfigFileMigration failed; MkStateDir: %v", err)
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return oldFile
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}
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err = os.WriteFile(newFile, contents, 0600)
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if err != nil {
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removeErr := os.Remove(newFile)
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if removeErr != nil {
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logf("TryConfigFileMigration failed; write newFile no cleanup: %v, remove err: %v",
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err, removeErr)
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return oldFile
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}
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logf("TryConfigFileMigration failed; write newFile: %v", err)
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return oldFile
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}
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logf("TryConfigFileMigration: successfully migrated: from %v to %v",
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oldFile, newFile)
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return newFile
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}
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