nim-cli-utils/cliutilspkg/daemonize.nim

69 lines
1.6 KiB
Nim

import posix
import os except sleep
## Daemonize
var
pidFileInner: string
fi, fo, fe: File
proc onStop(sig: cint) {.noconv.} =
close(fi)
close(fo)
close(fe)
removeFile(pidFileInner)
quit(QuitSuccess)
proc daemonize*(pidfile, si, so, se: string, daemonMain: proc(): void): Pid =
if fileExists(pidfile):
raise newException(IOError, "pidfile " & pidfile & " already exists, daemon already running?")
let pid1 = fork()
# Are we the child process?
if pid1 == 0:
# Yes, so let's get ready to execute the main code given to us.
discard chdir("/")
discard setsid()
discard umask(0)
# Fork again... but I'm not sure why.
let pid2 = fork()
# We don't need the intermediate process, so if we are not the child this
# time, lets just quit
if pid2 > 0: quit(QuitSuccess)
# If we are the grandchild let's set up our environment.
flushFile(stdout)
flushFile(stderr)
if si.len > 0:
fi = open(si, fmRead)
discard dup2(getFileHandle(fi), getFileHandle(stdin))
if so.len > 0:
fo = open(so, fmAppend)
discard dup2(getFileHandle(fo), getFileHandle(stdout))
if se.len > 0:
fe = open(se, fmAppend)
discard dup2(getFileHandle(fe), getFileHandle(stderr))
pidFileInner = pidfile
# Add hooks to cleanup after ourselves when we're asked to die.
signal(SIGINT, onStop)
signal(SIGTERM, onStop)
# Find out what our actual PID is and save it
let childPid = getpid()
writeFile(pidfile, $childPid)
# Finally, execute our main
daemonMain()
return pid1