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/* Copyright 1993-95 by Carl Harris, Jr. Copyright 1996 by Eric S. Raymond
* All rights reserved.
* For license terms, see the file COPYING in this directory.
*/
/***********************************************************************
module: daemon
project: popclient
programmer: Carl Harris, ceharris@mal.com
description: This module contains all of the code needed to
turn a process into a daemon for POSIX, SysV, and
BSD systems.
***********************************************************************/
#include <config.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/file.h>
#include <signal.h>
#include <fcntl.h>
#if defined(HAVE_SYS_WAIT_H)
# include <sys/wait.h>
#endif
#if defined(HAVE_UNISTD_H)
# include <unistd.h>
#endif
#include "popclient.h"
static void (*my_termhook)(void);
/******************************************************************
function: sigchld_handler
description: Process the SIGCHLD (a.k.a SIGCLD) signal by calling
a wait() variant to obtain the exit code of the
terminating process.
arguments: none.
ret. value: none (or undefined if REGSIGTYPE is int).
globals: none.
calls: none.
*****************************************************************/
RETSIGTYPE
sigchld_handler ()
{
pid_t pid;
#if defined(HAVE_UNION_WAIT)
union wait status;
#else
int status;
#endif
if (my_termhook)
(*my_termhook)();
#if defined(HAVE_WAIT3)
while ((pid = wait3(&status, WNOHANG, (struct rusage *) 0)) > 0)
; /* swallow 'em up. */
#elif defined(HAVE_WAITPID)
while ((pid = waitpid(-1, &status, WNOHANG)) > 0)
; /* swallow 'em up. */
#else /* Zooks! Nothing to do but wait(), and hope we don't block... */
wait(&status);
#endif
}
/******************************************************************
function: daemonize
description: become a daemon process; i.e. detach from the
control terminal, don't reacquire a control terminal,
become process group leader of our own process group,
and set up to catch child process termination signals.
arguments:
logfile file to direct stdout and stderr to, if non-NULL.
ret. value: none.
globals: refers to the address of sigchld_handler().
calls: none.
*****************************************************************/
int
daemonize (logfile, termhook)
const char *logfile;
void (*termhook)(void);
{
int fd;
pid_t childpid;
RETSIGTYPE sigchld_handler();
/* if we are started by init (process 1) via /etc/inittab we needn't
bother to detach from our process group context */
my_termhook = termhook;
if (getppid() == 1)
goto nottyDetach;
/* Ignore BSD terminal stop signals */
#ifdef SIGTTOU
signal(SIGTTOU, SIG_IGN);
#endif
#ifdef SIGTTIN
signal(SIGTTIN, SIG_IGN);
#endif
#ifdef SIGTSTP
signal(SIGTSTP, SIG_IGN);
#endif
/* In case we were not started in the background, fork and let
the parent exit. Guarantees that the child is not a process
group leader */
if ((childpid = fork()) < 0) {
perror("fork");
return(PS_IOERR);
}
else if (childpid > 0)
exit(0); /* parent */
/* Make ourselves the leader of a new process group with no
controlling terminal */
#if defined(HAVE_SETSID) /* POSIX */
/* POSIX makes this soooo easy to do */
if (setsid() < 0) {
perror("setsid");
return(PS_IOERR);
}
#elif defined(SIGTSTP) /* BSD */
/* change process group */
setpgrp(0, getpid());
/* lose controlling tty */
if ((fd = open("/dev/tty", O_RDWR)) >= 0) {
ioctl(fd, TIOCNOTTY, (char *) 0);
close(fd);
}
#else /* SVR3 and older */
/* change process group */
setpgrp();
/* lose controlling tty */
signal(SIGHUP, SIG_IGN);
if ((childpid = fork) < 0) {
perror("fork");
return(PS_IOERR);
}
else if (childpid > 0) {
exit(0); /* parent */
}
#endif
nottyDetach:
/* Close any/all open file descriptors */
#if defined(HAVE_GETDTABLESIZE)
for (fd = getdtablesize()-1; fd >= 0; fd--)
#elif defined(NOFILE)
for (fd = NOFILE-1; fd >= 0; fd--)
#else /* make an educated guess */
for (fd = 19; fd >= 0; fd--)
#endif
{
close(fd);
}
/* Reopen stdin descriptor on /dev/null */
if ((fd = open("/dev/null", O_RDWR)) < 0) { /* stdin */
perror("open: /dev/null");
return(PS_IOERR);
}
if (logfile)
fd = open(logfile, O_CREAT|O_WRONLY, 0777); /* stdout */
else
if (dup(fd) < 0) { /* stdout */
perror("dup");
return(PS_IOERR);
}
if (dup(fd) < 0) { /* stderr */
perror("dup");
return(PS_IOERR);
}
/* move to root directory, so we don't prevent filesystem unmounts */
chdir("/");
/* set our umask to something reasonable (we hope) */
#if defined(DEF_UMASK)
umask(DEF_UMASK);
#else
umask(022);
#endif
/* set up to catch child process termination signals */
signal(SIGCLD, sigchld_handler);
}
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