/
process.go
204 lines (187 loc) · 4.24 KB
/
process.go
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package main
/**
DUPLICATED from goagain + modded to use net.Conn
It enables process restart without droping net.Conn
*/
import (
"fmt"
"io"
"net"
"os"
"os/exec"
"os/signal"
"reflect"
"syscall"
log "github.com/Sirupsen/logrus"
)
// SignalChan accepts SIGINT, SIGTERM, SIGQUIT resp. SIGUSR2 signals for quit resp. restart
var SignalChan chan os.Signal
// Just alias some syscall signals
const (
SIGINT = syscall.SIGINT
SIGTERM = syscall.SIGTERM
SIGQUIT = syscall.SIGQUIT
SIGUSR2 = syscall.SIGUSR2
)
// Getpid return's current process pid
func Getpid() int {
return syscall.Getpid()
}
// Quit terminates bot
func Quit() {
SignalChan <- syscall.SIGQUIT
}
// Restart restart's bot
func Restart() {
SignalChan <- syscall.SIGUSR2
}
// Kill process specified in the environment with the signal specified in the
// environment; default to SIGQUIT.
func killParentAfterRestart() error {
var pid int
_, err := fmt.Sscan(os.Getenv("RESTART_PID"), &pid)
if io.EOF == err {
_, err = fmt.Sscan(os.Getenv("RESTART_PPID"), &pid)
}
if nil != err {
return err
}
log.Infoln("Sending parent GRAIN (pid: ", pid, ") QUIT signal")
return syscall.Kill(pid, syscall.SIGQUIT)
}
// Reconstruct a net.Conn from a file descriptior and name specified in the
// environment. Deal with Go's insistence on dup(2)ing file descriptors.
func findSocket() (l net.Conn, err error) {
var fd uintptr
if _, err = fmt.Sscan(os.Getenv("RESTART_FD"), &fd); nil != err {
return
}
l, err = net.FileConn(os.NewFile(fd, os.Getenv("RESTART_NAME")))
if nil != err {
return
}
switch l.(type) {
case *net.TCPConn, *net.UnixConn:
default:
err = fmt.Errorf(
"file descriptor is %T not *net.TCPConn or *net.UnixConn",
l,
)
return
}
if err = syscall.Close(int(fd)); nil != err {
return
}
return
}
// WaitOnSignals will block process until receives quit or restart signal
func (bot *Bot) WaitOnSignals(l net.Conn) error {
SignalChan = make(chan os.Signal, 2)
signal.Notify(
SignalChan,
syscall.SIGINT,
syscall.SIGTERM,
syscall.SIGQUIT,
syscall.SIGUSR2,
)
forked := false
for {
sig := <-SignalChan
switch sig {
case syscall.SIGTERM:
return nil //just unblock
case syscall.SIGINT:
return nil //just unblock
case syscall.SIGQUIT:
return nil //just unblock
case syscall.SIGUSR2:
if forked { //druhy a dalsi jen ukonci
return nil
}
forked = true
if err := bot.beforeFork(); nil != err {
log.Errorln("BeforeForkError:", err)
}
if err := forkAndExec(l); nil != err { //pri prvnim signalu udelej fork, vrat hodnotu jen kdyz bude chyba
return err
}
}
}
}
// Fork and exec this same image without dropping the net.Conn.
func forkAndExec(l net.Conn) error {
argv0, err := lookPath()
if nil != err {
return err
}
wd, err := os.Getwd()
if nil != err {
return err
}
fd, err := setEnvs(l)
if nil != err {
return err
}
if err := os.Setenv("RESTART_PID", ""); nil != err {
return err
}
if err := os.Setenv(
"RESTART_PPID",
fmt.Sprint(syscall.Getpid()),
); nil != err {
return err
}
files := make([]*os.File, fd+1)
files[syscall.Stdin] = os.Stdin
files[syscall.Stdout] = os.Stdout
files[syscall.Stderr] = os.Stderr
addr := l.RemoteAddr()
files[fd] = os.NewFile(
fd,
fmt.Sprintf("%s:%s->", addr.Network(), addr.String()),
)
p, err := os.StartProcess(argv0, os.Args, &os.ProcAttr{
Dir: wd,
Env: os.Environ(),
Files: files,
Sys: &syscall.SysProcAttr{},
})
if nil != err {
return err
}
log.Infoln("Spawned new GRAIN child (pid: ", p.Pid, ")")
if err = os.Setenv("RESTART_PID", fmt.Sprint(p.Pid)); nil != err {
return err
}
return nil
}
func lookPath() (argv0 string, err error) {
argv0, err = exec.LookPath(os.Args[0])
if nil != err {
return
}
if _, err = os.Stat(argv0); nil != err {
return
}
return
}
func setEnvs(l net.Conn) (fd uintptr, err error) {
v := reflect.ValueOf(l).Elem().FieldByName("fd").Elem()
fd = uintptr(v.FieldByName("sysfd").Int())
_, _, e1 := syscall.Syscall(syscall.SYS_FCNTL, fd, syscall.F_SETFD, 0)
if 0 != e1 {
err = e1
return
}
if err = os.Setenv("RESTART_FD", fmt.Sprint(fd)); nil != err {
return
}
addr := l.RemoteAddr()
if err = os.Setenv(
"RESTART_NAME",
fmt.Sprintf("%s:%s->", addr.Network(), addr.String()),
); nil != err {
return
}
return
}