51 lines
1.4 KiB
Go
51 lines
1.4 KiB
Go
package core
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import (
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"os"
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"path/filepath"
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)
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// AtomicWriteFile writes data to a file atomically by first writing to a
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// temporary file in the same directory, syncing, then renaming over the target.
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// This prevents data loss / corruption on crash.
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func AtomicWriteFile(path string, data []byte, perm os.FileMode) error {
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dir := filepath.Dir(path)
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tmp, err := os.CreateTemp(dir, ".tmp-*")
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if err != nil {
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return err
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}
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tmpPath := tmp.Name()
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if _, err := tmp.Write(data); err != nil {
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tmp.Close()
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os.Remove(tmpPath)
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return err
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}
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if err := tmp.Sync(); err != nil {
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tmp.Close()
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os.Remove(tmpPath)
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return err
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}
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if err := tmp.Close(); err != nil {
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os.Remove(tmpPath)
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return err
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}
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if err := os.Chmod(tmpPath, perm); err != nil {
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os.Remove(tmpPath)
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return err
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}
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if err := os.Rename(tmpPath, path); err != nil {
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// Rename can fail when the destination is a directory, the
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// destination's filesystem differs from the temp dir's (rare given
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// CreateTemp uses the same dir, but possible with bind mounts), or
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// the destination is locked by another process on Windows. In any
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// of those cases the temp file is now an orphaned `.tmp-*` we
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// created — clean it up so repeated failures don't litter the
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// directory and confuse later directory scans (e.g. cron / session
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// stores that walk their parent dir).
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os.Remove(tmpPath)
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return err
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}
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return nil
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}
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