wehub-resource-sync
65 lines
1.6 KiB
Go
65 lines
1.6 KiB
Go
package fileutil
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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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)
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// WriteFileAtomic replaces path only after data has been written and synced.
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func WriteFileAtomic(path string, data []byte, perm os.FileMode) (err error) {
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dir := filepath.Dir(path)
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if err := os.MkdirAll(dir, 0o700); err != nil {
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return fmt.Errorf("create directory: %w", err)
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}
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if err := os.Chmod(dir, 0o700); err != nil {
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return fmt.Errorf("secure directory: %w", err)
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}
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if info, statErr := os.Stat(path); statErr == nil {
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perm &= info.Mode().Perm()
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} else if !os.IsNotExist(statErr) {
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return fmt.Errorf("inspect existing file: %w", statErr)
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}
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tmp, err := os.CreateTemp(dir, ".tmp-*")
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if err != nil {
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return fmt.Errorf("create temporary file: %w", err)
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}
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tmpPath := tmp.Name()
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defer func() {
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if tmp != nil {
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if closeErr := tmp.Close(); err == nil && closeErr != nil {
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err = fmt.Errorf("close temporary file: %w", closeErr)
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}
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}
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_ = os.Remove(tmpPath)
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}()
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if err = tmp.Chmod(perm); err != nil {
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return fmt.Errorf("set temporary file permissions: %w", err)
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}
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if _, err = tmp.Write(data); err != nil {
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return fmt.Errorf("write temporary file: %w", err)
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}
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if err = tmp.Sync(); err != nil {
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return fmt.Errorf("sync temporary file: %w", err)
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}
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if err = tmp.Close(); err != nil {
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return fmt.Errorf("close temporary file: %w", err)
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}
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tmp = nil
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if err = os.Rename(tmpPath, path); err != nil {
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return fmt.Errorf("replace file: %w", err)
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}
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d, openErr := os.Open(dir)
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if openErr != nil {
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return fmt.Errorf("open parent directory: %w", openErr)
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}
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defer d.Close()
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if err = d.Sync(); err != nil {
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return fmt.Errorf("sync parent directory: %w", err)
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}
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return nil
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}
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