52 lines
1.3 KiB
Go
52 lines
1.3 KiB
Go
// Package configfile publishes default configuration without replacing user files.
|
|
package configfile
|
|
|
|
import (
|
|
"encoding/json"
|
|
"errors"
|
|
"fmt"
|
|
"log/slog"
|
|
"os"
|
|
"path/filepath"
|
|
)
|
|
|
|
// Ensure publishes a complete JSON file only when path does not exist.
|
|
// Linking a same-directory temporary file makes publication atomic and refuses
|
|
// to replace a configuration created by another process in the meantime.
|
|
func Ensure(path string, defaults any) error {
|
|
if _, err := os.Stat(path); err == nil {
|
|
return nil
|
|
} else if !errors.Is(err, os.ErrNotExist) {
|
|
return err
|
|
}
|
|
data, err := json.MarshalIndent(defaults, "", " ")
|
|
if err != nil {
|
|
return err
|
|
}
|
|
if err = os.MkdirAll(filepath.Dir(path), 0755); err != nil {
|
|
return fmt.Errorf("create configuration directory: %w", err)
|
|
}
|
|
file, err := os.CreateTemp(filepath.Dir(path), ".config-*.tmp")
|
|
if err != nil {
|
|
return err
|
|
}
|
|
defer func() { _ = os.Remove(file.Name()) }()
|
|
if _, err = file.Write(append(data, '\n')); err == nil {
|
|
err = file.Sync()
|
|
}
|
|
closeErr := file.Close()
|
|
if err != nil {
|
|
return err
|
|
}
|
|
if closeErr != nil {
|
|
return closeErr
|
|
}
|
|
if err = os.Link(file.Name(), path); errors.Is(err, os.ErrExist) {
|
|
return nil
|
|
} else if err != nil {
|
|
return fmt.Errorf("create default configuration %s: %w", path, err)
|
|
}
|
|
slog.Info("default configuration created", "path", path)
|
|
return nil
|
|
}
|