/*
* 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 <string.h>
#include <sys/types.h>
#ifdef HAVE_SYS_WAIT_H
#include <sys/wait.h>
#endif
#ifdef HAVE_FCNTL_H
#include <fcntl.h>
#else /* !HAVE_FCNTL_H */
#ifdef HAVE_SYS_FCNTL_H
#include <sys/fcntl.h>
#endif /* HAVE_SYS_FCNTL_H */
#endif /* !HAVE_FCNTL_H */
#include <sys/stat.h> /* get umask(2) prototyped */
#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_SETSID) && defined(SIGTSTP)
#if defined(HAVE_TERMIOS_H)
# include <termios.h> /* for TIOCNOTTY under Linux */
#endif
#if !defined(TIOCNOTTY) && defined(HAVE_SGTTY_H)
# include <sgtty.h> /* for TIOCNOTTY under NEXTSTEP */
#endif
#endif /* !defined(HAVE_SETSID) && defined(SIGTSTP) */
/* BSD portability hack */
#if !defined(SIGCHLD) && defined(SIGCLD)
#define SIGCHLD SIGCLD
#endif
#include "fetchmail.h"
#include "tunable.h"
static RETSIGTYPE
sigchld_handler (int sig)
/* process SIGCHLD to obtain the exit code of the terminating process */
{
#if defined(HAVE_WAITPID) /* the POSIX way */
int status;
while (waitpid(-1, &status, WNOHANG) > 0)
continue; /* swallow 'em up. */
#elif defined(HAVE_WAIT3) /* the BSD way */
pid_t pid;
#if defined(HAVE_UNION_WAIT) && !defined(__FreeBSD__)
union wait status;
#else
int status;
#endif
while ((pid = wait3(&status, WNOHANG, 0)) > 0)
continue; /* swallow 'em up. */
#else /* Zooks! Nothing to do but wait(), and hope we don't block... */
int status;
wait(&status);
#endif
lastsig = SIGCHLD;
(void)sig;
}
RETSIGTYPE null_signal_handler(int sig) { (void)sig; }
SIGHANDLERTYPE set_signal_handler(int sig, SIGHANDLERTYPE handler)
/*
* This function is called by other parts of the program to
* setup the signal handler after a change to the signal context.
* This is done to improve robustness of the signal handling code.
* It has the same prototype as signal(2).
*/
{
SIGHANDLERTYPE rethandler;
#ifdef HAVE_SIGACTION
struct sigaction sa_new, sa_old;
memset (&sa_new, 0, sizeof sa_new);
sigemptyset (&sa_new.sa_mask);
sa_new.sa_handler = handler;
sa_new.sa_flags = 0;
#ifdef SA_RESTART /* SunOS 4.1 portability hack */
/* system call should restart on all signals except SIGALRM */
if (sig != SIGALRM)
sa_new.sa_flags |= SA_RESTART;
#endif
#ifdef SA_NOCLDSTOP /* SunOS 4.1 portability hack */
if (sig == SIGCHLD)
sa_new.sa_flags |= SA_NOCLDSTOP;
#endif
sigaction(sig, &sa_new, &sa_old);
rethandler = sa_old.sa_handler;
#if defined(SIGPWR)
if (sig == SIGCHLD)
sigaction(SIGPWR, &sa_new, NULL);
#endif
#else /* HAVE_SIGACTION */
rethandler = signal(sig, handler);
#if defined(SIGPWR)
if (sig == SIGCHLD)
signal(SIGPWR, handler);
#endif
/* system call should restart on all signals except SIGALRM */
siginterrupt(sig, sig == SIGALRM);
#endif /* HAVE_SIGACTION */
return rethandler;
}
void deal_with_sigchld(void)
{
set_signal_handler(SIGCHLD, sigchld_handler);
}
int
daemonize (const char *logfile)
/* detach from control TTY, become process group leader, catch SIGCHLD */
{
int fd, logfd;
pid_t childpid;
/* 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
set_signal_handler(SIGTTOU, SIG_IGN);
#endif
#ifdef SIGTTIN
set_signal_handler(SIGTTIN, SIG_IGN);
#endif
#ifdef SIGTSTP
set_signal_handler(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) {
report(stderr, "fork (%s)\n", strerror(errno));
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) {
report(stderr, "setsid (%s)\n", strerror(errno));
return(PS_IOERR);
}
#elif defined(SIGTSTP) /* BSD */
/* change process group */
#ifndef __EMX__
setpgrp(0, getpid());
#endif
/* lose controlling tty */
if ((fd = open("/dev/tty", O_RDWR)) >= 0) {
ioctl(fd, TIOCNOTTY, (char *) 0);
close(fd); /* not checking should be safe, there were no writes */
}
#else /* SVR3 and older */
/* change process group */
#ifndef __EMX__
setpgrp();
#endif
/* lose controlling tty */
set_signal_handler(SIGHUP, SIG_IGN);
if ((childpid = fork()) < 0) {
report(stderr, "fork (%s)\n", strerror(errno));
return(PS_IOERR);
}
else if (childpid > 0) {
exit(0); /* parent */
}
#endif
nottyDetach:
(void)close(0);
/* Reopen stdin descriptor on /dev/null */
if (open("/dev/null", O_RDWR) < 0) { /* stdin */
report(stderr, "cannot open /dev/null: %s\n", strerror(errno));
return(PS_IOERR);
}
if (logfile)
{
if ((logfd = open(logfile, O_CREAT|O_WRONLY|O_APPEND, 0666)) < 0) { /* stdout */
report(stderr, "cannot open %s: %s\n", logfile, strerror(errno));
return PS_IOERR;
}
} else
logfd = 0; /* else use /dev/null */
/* Close any/all open file descriptors */
#if defined(HAVE_GETDTABLESIZE)
fd = getdtablesize() - 1;
#elif defined(NOFILE)
fd = NOFILE - 1;
#else /* make an educated guess */
fd = 1023;
#endif
while (fd >= 1) {
if (fd != logfd)
close(fd); /* not checking this should be safe, no writes */
-- fd;
}
if (dup(logfd) < 0 /* stdout */
|| ((logfd == 0 || logfd >= 3) && dup(logfd) < 0)) { /* stderr */
report(stderr, "dup (%s)\n", strerror(errno));
return(PS_IOERR);
}
#ifdef HAVE_GETCWD
/* move to root directory, so we don't prevent filesystem unmounts */
chdir("/");
#endif
/* set our umask to something reasonable (we hope) */
#if defined(DEF_UMASK)
umask(DEF_UMASK);
#else
umask(022);
#endif
deal_with_sigchld();
return(0);
}
flag is_a_file(int fd)
/* is the given fd attached to a file? (used to control logging) */
{
struct stat stbuf;
/*
* We'd like just to return 1 on (S_IFREG | S_IFBLK),
* but weirdly enough, Linux ptys seem to have S_IFBLK
* so this test would fail when run on an xterm.
*/
if (isatty(fd) || fstat(fd, &stbuf))
return(0);
else if (stbuf.st_mode & (S_IFREG))
return(1);
return(0);
}
/* daemon.c ends here */
