libgocryptfs/daemonize.go

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package main
import (
"fmt"
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"os"
"os/exec"
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"os/signal"
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"syscall"
"github.com/rfjakob/gocryptfs/internal/exitcodes"
"github.com/rfjakob/gocryptfs/internal/tlog"
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)
// The child sends us USR1 if the mount was successful. Exit with error code
// 0 if we get it.
func exitOnUsr1() {
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c := make(chan os.Signal, 1)
signal.Notify(c, syscall.SIGUSR1)
go func() {
<-c
os.Exit(0)
}()
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}
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// forkChild - execute ourselves once again, this time with the "-fg" flag, and
// wait for SIGUSR1 or child exit.
// This is a workaround for the missing true fork function in Go.
func forkChild() int {
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name := os.Args[0]
newArgs := []string{"-fg", fmt.Sprintf("-notifypid=%d", os.Getpid())}
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newArgs = append(newArgs, os.Args[1:]...)
c := exec.Command(name, newArgs...)
c.Stdout = os.Stdout
c.Stderr = os.Stderr
c.Stdin = os.Stdin
exitOnUsr1()
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err := c.Start()
if err != nil {
tlog.Fatal.Printf("forkChild: starting %s failed: %v\n", name, err)
return exitcodes.ForkChild
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}
err = c.Wait()
if err != nil {
if exiterr, ok := err.(*exec.ExitError); ok {
if waitstat, ok := exiterr.Sys().(syscall.WaitStatus); ok {
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os.Exit(waitstat.ExitStatus())
}
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}
tlog.Fatal.Printf("forkChild: wait returned an unknown error: %v\n", err)
return exitcodes.ForkChild
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}
// The child exited with 0 - let's do the same.
return 0
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}