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/*
* daemon.c -- turn a process into a daemon under POSIX, SYSV, BSD.
*
* For license terms, see the file COPYING in this directory.
*/
#include <config.h>
#include <stdio.h>
#include <errno.h>
#include <signal.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/file.h>
#include <sys/wait.h>
#include <sys/fcntl.h> /* Solaris 2.5 requires this */
#if defined(HAVE_UNISTD_H)
#include <unistd.h>
#endif
#if defined(STDC_HEADERS)
#include <stdlib.h>
#endif
#if defined(QNX)
#include <unix.h>
#endif
#if defined(HAVE_SGTTY_H)
# include <sgtty.h> /* for TIOCNOTTY under NEXTSTEP */
#endif
/* BSD portability hack */
#if !defined(SIGCHLD) && defined(SICHLD)
#define SIGCHLD SIGCLD
#endif
#include "fetchmail.h"
#include "tunable.h"
RETSIGTYPE
sigchld_handler (int sig)
/* process SIGCHLD to obtain the exit code of the terminating process */
{
pid_t pid;
#if defined(HAVE_UNION_WAIT)
union wait status;
#else
int status;
#endif
#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
}
int
daemonize (const char *logfile, void (*termhook)(int))
/* detach from control TTY, become process group leader, catch SIGCHLD */
{
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 */
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) {
error(0, errno, "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) {
error(0, errno, "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) {
error(0, errno, "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 */
error(0, errno, "open: /dev/null");
return(PS_IOERR);
}
if (logfile)
fd = open(logfile, O_CREAT|O_WRONLY|O_APPEND, 0777); /* stdout */
else
if (dup(fd) < 0) { /* stdout */
error(0, errno, "dup");
return(PS_IOERR);
}
if (dup(fd) < 0) { /* stderr */
error(0, errno, "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(SIGCHLD, sigchld_handler);
#if defined(SIGPWR)
signal(SIGPWR, sigchld_handler);
#endif
return(0);
}
/* daemon.c ends here */
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