56 lines
1.4 KiB
Go
56 lines
1.4 KiB
Go
// Package pidfile provides structure and helper functions to create and remove
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// PID file. A PID file is usually a file used to store the process ID of a
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// running process.
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package pidfile
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import (
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"fmt"
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"io/ioutil"
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"os"
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"path/filepath"
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"strconv"
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"strings"
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"github.com/docker/docker/pkg/system"
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)
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// PIDFile is a file used to store the process ID of a running process.
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type PIDFile struct {
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path string
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}
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func checkPIDFileAlreadyExists(path string) error {
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if pidByte, err := ioutil.ReadFile(path); err == nil {
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pidString := strings.TrimSpace(string(pidByte))
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if pid, err := strconv.Atoi(pidString); err == nil {
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if processExists(pid) {
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return fmt.Errorf("pid file found, ensure docker is not running or delete %s", path)
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}
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}
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}
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return nil
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}
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// New creates a PIDfile using the specified path.
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func New(path string) (*PIDFile, error) {
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if err := checkPIDFileAlreadyExists(path); err != nil {
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return nil, err
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}
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// Note MkdirAll returns nil if a directory already exists
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if err := system.MkdirAll(filepath.Dir(path), os.FileMode(0755)); err != nil {
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return nil, err
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}
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if err := ioutil.WriteFile(path, []byte(fmt.Sprintf("%d", os.Getpid())), 0644); err != nil {
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return nil, err
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}
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return &PIDFile{path: path}, nil
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}
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// Remove removes the PIDFile.
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func (file PIDFile) Remove() error {
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if err := os.Remove(file.path); err != nil {
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return err
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}
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return nil
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}
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