55 lines
1.3 KiB
Go
55 lines
1.3 KiB
Go
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// Copyright 2022 Listware
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package pid
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import (
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"fmt"
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"os"
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"strconv"
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"syscall"
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)
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// File - is a pid-file
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type File string
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func (f File) String() string {
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return string(f)
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}
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// Write a pid file, but first make sure it doesn't exist with a running pid.
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func (f File) Write() error {
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// Read in the pid file as a slice of bytes.
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if piddata, err := os.ReadFile(f.String()); err == nil {
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// Convert the file contents to an integer.
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if pid, err := strconv.Atoi(string(piddata)); err == nil {
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// Look for the pid in the process list.
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if process, err := os.FindProcess(pid); err == nil {
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// Send the process a signal zero kill.
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if err := process.Signal(syscall.Signal(0)); err == nil {
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// We only get an error if the pid isn't running, or it's not ours.
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return fmt.Errorf("pid already running: %d", pid)
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}
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}
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}
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}
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// If we get here, then the pidfile didn't exist,
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// or the pid in it doesn't belong to the user running this app.
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return os.WriteFile(f.String(), []byte(fmt.Sprintf("%d", os.Getpid())), 0664)
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}
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// Remove pid file
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func (f File) Remove() error {
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return os.Remove(f.String())
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}
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// PID - process id
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func (f File) PID() (pid int, err error) {
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var piddata []byte
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piddata, err = os.ReadFile(f.String())
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if err != nil {
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return
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}
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pid, err = strconv.Atoi(string(piddata))
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return
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}
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