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