rclone/lib/daemonize/daemon_unix.go
Ivan Andreev 8b8a943dd8 mountlib: correctly daemonize for compatibility with automount - #5593
This patch will:
- add --daemon-wait flag to control the time to wait for background mount
- remove dependency on sevlyar/go-daemon and implement backgrounding directly
- avoid setsid during backgrounding as it can result in race under Automount
- provide a fallback PATH to correctly run `fusermount` under systemd as it
  runs mount units without standard environment variables
- correctly handle ^C pressed while background process is being setting up
2021-10-02 23:45:16 +03:00

59 lines
1.3 KiB
Go

// Daemonization interface for Unix platforms (implementation)
//go:build !windows && !plan9 && !js
// +build !windows,!plan9,!js
package daemonize
import (
"os"
"syscall"
"github.com/rclone/rclone/fs"
)
// StartDaemon runs background twin of current process.
// It executes separate parts of code in child and parent processes.
// Returns child process pid in the parent or nil in the child.
// The method looks like a fork but safe for goroutines.
func StartDaemon(args []string) (*os.Process, error) {
if fs.IsDaemon() {
// This process is already daemonized
return nil, nil
}
env := append(os.Environ(), fs.DaemonMarkVar+"="+fs.DaemonMarkChild)
me, err := os.Executable()
if err != nil {
me = os.Args[0]
}
null, err := os.Open(os.DevNull)
if err != nil {
return nil, err
}
files := []*os.File{
null, // (0) stdin
null, // (1) stdout
null, // (2) stderr
}
sysAttr := &syscall.SysProcAttr{
// setsid (https://linux.die.net/man/2/setsid) in the child process will reset
// its process group id (PGID) to its PID thus detaching it from parent.
// This would make autofs fail because it detects mounting process by its PGID.
Setsid: false,
}
attr := &os.ProcAttr{
Env: env,
Files: files,
Sys: sysAttr,
}
daemon, err := os.StartProcess(me, args, attr)
if err != nil {
return nil, err
}
return daemon, nil
}