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// Package pidfile manages pid files.
package pidfile
import (
"bytes"
"errors"
"flag"
"fmt"
"io/ioutil"
"os"
"path/filepath"
"strconv"
"github.com/facebookgo/atomicfile"
)
var (
errNotConfigured = errors.New("pidfile not configured")
pidfile = flag.String("pidfile", "", "If specified, write pid to file.")
)
// IsNotConfigured returns true if the error indicates the pidfile location has
// not been configured.
func IsNotConfigured(err error) bool {
if err == errNotConfigured {
return true
}
return false
}
// GetPidfilePath returns the configured pidfile path.
func GetPidfilePath() string {
return *pidfile
}
// SetPidfilePath sets the pidfile path.
func SetPidfilePath(p string) {
*pidfile = p
}
// Write the pidfile based on the flag. It is an error if the pidfile hasn't
// been configured.
func Write() error {
if *pidfile == "" {
return errNotConfigured
}
if err := os.MkdirAll(filepath.Dir(*pidfile), os.FileMode(0755)); err != nil {
return err
}
file, err := atomicfile.New(*pidfile, os.FileMode(0644))
if err != nil {
return fmt.Errorf("error opening pidfile %s: %s", *pidfile, err)
}
defer file.Close() // in case we fail before the explicit close
_, err = fmt.Fprintf(file, "%d", os.Getpid())
if err != nil {
return err
}
err = file.Close()
if err != nil {
return err
}
return nil
}
// Read the pid from the configured file. It is an error if the pidfile hasn't
// been configured.
func Read() (int, error) {
if *pidfile == "" {
return 0, errNotConfigured
}
d, err := ioutil.ReadFile(*pidfile)
if err != nil {
return 0, err
}
pid, err := strconv.Atoi(string(bytes.TrimSpace(d)))
if err != nil {
return 0, fmt.Errorf("error parsing pid from %s: %s", *pidfile, err)
}
return pid, nil
}
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