sysdep.c

/* Interfaces to system-dependent kernel and library entries.
   Copyright (C) 1985, 1986, 1987, 1988, 1993, 1994, 1995, 1999, 2000, 2001,
                 2002, 2003, 2004, 2005 Free Software Foundation, Inc.

This file is part of GNU Emacs.

GNU Emacs is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.

GNU Emacs is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with GNU Emacs; see the file COPYING.  If not, write to
the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
Boston, MA 02110-1301, USA.  */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <signal.h>
#include <stdio.h>
#include <setjmp.h>
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#include "lisp.h"
/* Including stdlib.h isn't necessarily enough to get srandom
   declared, e.g. without __USE_XOPEN_EXTENDED with glibc 2.  */
#ifdef HAVE_RANDOM
#if 0 /* It turns out that defining _OSF_SOURCE in osf5-0.h gets
	 random prototyped as returning `int'.  It looks to me as
	 though the best way to DTRT is to prefer the rand48 functions
	 (per libc.info).  -- fx */
extern long int random P_ ((void));
#endif
#if 0 /* Don't prototype srandom; it takes an unsigned argument on
	 some systems, and an unsigned long on others, like FreeBSD
	 4.1.  */
extern void srandom P_ ((unsigned int));
#endif
#endif

#include "blockinput.h"
#undef NULL

#ifdef MAC_OS8
/* It is essential to include stdlib.h so that this file picks up
   the correct definitions of rand, srand, and RAND_MAX.
   Otherwise random numbers will not work correctly.  */
#include <stdlib.h>

#ifndef subprocesses
/* Nonzero means delete a process right away if it exits (process.c).  */
static int delete_exited_processes;
#endif
#endif  /* MAC_OS8 */

#ifdef WINDOWSNT
#define read sys_read
#define write sys_write
#include <windows.h>
#ifndef NULL
#define NULL 0
#endif
#endif /* not WINDOWSNT */

/* Does anyone other than VMS need this? */
#ifndef fwrite
#define sys_fwrite fwrite
#else
#undef fwrite
#endif

#include <sys/types.h>
#include <sys/stat.h>
#include <errno.h>

#ifdef HAVE_SETPGID
#if !defined (USG) || defined (BSD_PGRPS)
#undef setpgrp
#define setpgrp setpgid
#endif
#endif

/* Get SI_SRPC_DOMAIN, if it is available.  */
#ifdef HAVE_SYS_SYSTEMINFO_H
#include <sys/systeminfo.h>
#endif

#ifdef MSDOS	/* Demacs 1.1.2 91/10/20 Manabu Higashida, MW Aug 1993 */
#include <dos.h>
#include "dosfns.h"
#include "msdos.h"
#include <sys/param.h>

#if __DJGPP__ > 1
extern int etext;
extern unsigned start __asm__ ("start");
#endif
#endif

#ifndef USE_CRT_DLL
#ifndef errno
extern int errno;
#endif
#endif

#ifdef VMS
#include <rms.h>
#include <ttdef.h>
#include <tt2def.h>
#include <iodef.h>
#include <ssdef.h>
#include <descrip.h>
#include <fibdef.h>
#include <atrdef.h>
#include <ctype.h>
#include <string.h>
#ifdef __GNUC__
#include <sys/file.h>
#else
#include <file.h>
#endif
#undef F_SETFL
#ifndef RAB$C_BID
#include <rab.h>
#endif
#define MAXIOSIZE (32 * PAGESIZE) /* Don't I/O more than 32 blocks at a time */
#endif /* VMS */

#ifndef VMS
#include <sys/file.h>
#endif /* not VMS */

#ifdef HAVE_FCNTL_H
#include <fcntl.h>
#endif

#ifndef MSDOS
#include <sys/ioctl.h>
#endif

#include "systty.h"
#include "syswait.h"

#ifdef BROKEN_TIOCGWINSZ
#undef TIOCGWINSZ
#undef TIOCSWINSZ
#endif

#if defined (USG) || defined (DGUX)
#include <sys/utsname.h>
#ifndef MEMORY_IN_STRING_H
#include <memory.h>
#endif
#if defined (TIOCGWINSZ) || defined (ISC4_0)
#ifdef NEED_SIOCTL
#include <sys/sioctl.h>
#endif
#ifdef NEED_PTEM_H
#include <sys/stream.h>
#include <sys/ptem.h>
#endif
#endif /* TIOCGWINSZ or ISC4_0 */
#endif /* USG or DGUX */

extern int quit_char;

#include "keyboard.h"
#include "frame.h"
#include "window.h"
#include "termhooks.h"
#include "termchar.h"
#include "termopts.h"
#include "dispextern.h"
#include "process.h"

#ifdef WINDOWSNT
#include <direct.h>
/* In process.h which conflicts with the local copy.  */
#define _P_WAIT 0
int _CRTAPI1 _spawnlp (int, const char *, const char *, ...);
int _CRTAPI1 _getpid (void);
#endif

#ifdef NONSYSTEM_DIR_LIBRARY
#include "ndir.h"
#endif /* NONSYSTEM_DIR_LIBRARY */

#include "syssignal.h"
#include "systime.h"
#ifdef HAVE_UTIME_H
#include <utime.h>
#endif

#ifndef HAVE_UTIMES
#ifndef HAVE_STRUCT_UTIMBUF
/* We want to use utime rather than utimes, but we couldn't find the
   structure declaration.  We'll use the traditional one.  */
struct utimbuf {
  long actime;
  long modtime;
};
#endif
#endif

/* LPASS8 is new in 4.3, and makes cbreak mode provide all 8 bits.  */
#ifndef LPASS8
#define LPASS8 0
#endif

#ifdef BSD4_1
#define LNOFLSH 0100000
#endif

static int baud_convert[] =
#ifdef BAUD_CONVERT
  BAUD_CONVERT;
#else
  {
    0, 50, 75, 110, 135, 150, 200, 300, 600, 1200,
    1800, 2400, 4800, 9600, 19200, 38400
  };
#endif

#ifdef HAVE_SPEED_T
#include <termios.h>
#else
#if defined (HAVE_LIBNCURSES) && ! defined (NCURSES_OSPEED_T)
#else
#if defined (HAVE_TERMIOS_H) && defined (GNU_LINUX)
#include <termios.h>
#endif
#endif
#endif

int emacs_ospeed;

/* The file descriptor for Emacs's input terminal.
   Under Unix, this is normally zero except when using X;
   under VMS, we place the input channel number here.  */
int input_fd;

void croak P_ ((char *));

#ifdef AIXHFT
void hft_init ();
void hft_reset ();
#endif

/* Temporary used by `sigblock' when defined in terms of signprocmask.  */

SIGMASKTYPE sigprocmask_set;


/* Specify a different file descriptor for further input operations.  */

void
change_input_fd (fd)
     int fd;
{
  input_fd = fd;
}

/* Discard pending input on descriptor input_fd.  */

void
discard_tty_input ()
{
#ifndef WINDOWSNT
  struct emacs_tty buf;

  if (noninteractive)
    return;

  /* Discarding input is not safe when the input could contain
     replies from the X server.  So don't do it.  */
  if (read_socket_hook)
    return;

#ifdef VMS
  end_kbd_input ();
  SYS$QIOW (0, input_fd, IO$_READVBLK|IO$M_PURGE, input_iosb, 0, 0,
	    &buf.main, 0, 0, terminator_mask, 0, 0);
  queue_kbd_input ();
#else /* not VMS */
#ifdef APOLLO
  {
    int zero = 0;
    ioctl (input_fd, TIOCFLUSH, &zero);
  }
#else /* not Apollo */
#ifdef MSDOS    /* Demacs 1.1.1 91/10/16 HIRANO Satoshi */
  while (dos_keyread () != -1)
    ;
#else /* not MSDOS */
  EMACS_GET_TTY (input_fd, &buf);
  EMACS_SET_TTY (input_fd, &buf, 0);
#endif /* not MSDOS */
#endif /* not Apollo */
#endif /* not VMS */
#endif /* not WINDOWSNT */
}

#ifdef SIGTSTP

/* Arrange for character C to be read as the next input from
   the terminal.  */

void
#ifdef PROTOTYPES
stuff_char (char c)
#else
stuff_char (c)
     char c;
#endif
{
  if (read_socket_hook)
    return;

/* Should perhaps error if in batch mode */
#ifdef TIOCSTI
  ioctl (input_fd, TIOCSTI, &c);
#else /* no TIOCSTI */
  error ("Cannot stuff terminal input characters in this version of Unix");
#endif /* no TIOCSTI */
}

#endif /* SIGTSTP */

void
init_baud_rate ()
{
  if (noninteractive)
    emacs_ospeed = 0;
  else
    {
#ifdef INIT_BAUD_RATE
      INIT_BAUD_RATE ();
#else
#ifdef DOS_NT
    emacs_ospeed = 15;
#else  /* not DOS_NT */
#ifdef VMS
      struct sensemode sg;

      SYS$QIOW (0, input_fd, IO$_SENSEMODE, &sg, 0, 0,
		&sg.class, 12, 0, 0, 0, 0 );
      emacs_ospeed = sg.xmit_baud;
#else /* not VMS */
#ifdef HAVE_TERMIOS
      struct termios sg;

      sg.c_cflag = B9600;
      tcgetattr (input_fd, &sg);
      emacs_ospeed = cfgetospeed (&sg);
#if defined (USE_GETOBAUD) && defined (getobaud)
      /* m88k-motorola-sysv3 needs this (ghazi@noc.rutgers.edu) 9/1/94. */
      if (emacs_ospeed == 0)
        emacs_ospeed = getobaud (sg.c_cflag);
#endif
#else /* neither VMS nor TERMIOS */
#ifdef HAVE_TERMIO
      struct termio sg;

      sg.c_cflag = B9600;
#ifdef HAVE_TCATTR
      tcgetattr (input_fd, &sg);
#else
      ioctl (input_fd, TCGETA, &sg);
#endif
      emacs_ospeed = sg.c_cflag & CBAUD;
#else /* neither VMS nor TERMIOS nor TERMIO */
      struct sgttyb sg;

      sg.sg_ospeed = B9600;
      if (ioctl (input_fd, TIOCGETP, &sg) < 0)
	abort ();
      emacs_ospeed = sg.sg_ospeed;
#endif /* not HAVE_TERMIO */
#endif /* not HAVE_TERMIOS */
#endif /* not VMS */
#endif /* not DOS_NT */
#endif /* not INIT_BAUD_RATE */
    }

  baud_rate = (emacs_ospeed < sizeof baud_convert / sizeof baud_convert[0]
	       ? baud_convert[emacs_ospeed] : 9600);
  if (baud_rate == 0)
    baud_rate = 1200;
}

/*ARGSUSED*/
void
set_exclusive_use (fd)
     int fd;
{
#ifdef FIOCLEX
  ioctl (fd, FIOCLEX, 0);
#endif
  /* Ok to do nothing if this feature does not exist */
}

#ifndef subprocesses

wait_without_blocking ()
{
#ifdef BSD_SYSTEM
  wait3 (0, WNOHANG | WUNTRACED, 0);
#else
  croak ("wait_without_blocking");
#endif
  synch_process_alive = 0;
}

#endif /* not subprocesses */

int wait_debugging;   /* Set nonzero to make following function work under dbx
			 (at least for bsd).  */

SIGTYPE
wait_for_termination_signal ()
{}

/* Wait for subprocess with process id `pid' to terminate and
   make sure it will get eliminated (not remain forever as a zombie) */

void
wait_for_termination (pid)
     int pid;
{
  while (1)
    {
#ifdef subprocesses
#ifdef VMS
      int status;

      status = SYS$FORCEX (&pid, 0, 0);
      break;
#else /* not VMS */
#if defined (BSD_SYSTEM) || (defined (HPUX) && !defined (HPUX_5))
      /* Note that kill returns -1 even if the process is just a zombie now.
	 But inevitably a SIGCHLD interrupt should be generated
	 and child_sig will do wait3 and make the process go away. */
      /* There is some indication that there is a bug involved with
	 termination of subprocesses, perhaps involving a kernel bug too,
	 but no idea what it is.  Just as a hunch we signal SIGCHLD to see
	 if that causes the problem to go away or get worse.  */
      sigsetmask (sigmask (SIGCHLD));
      if (0 > kill (pid, 0))
	{
	  sigsetmask (SIGEMPTYMASK);
	  kill (getpid (), SIGCHLD);
	  break;
	}
      if (wait_debugging)
	sleep (1);
      else
	sigpause (SIGEMPTYMASK);
#else /* not BSD_SYSTEM, and not HPUX version >= 6 */
#if defined (UNIPLUS)
      if (0 > kill (pid, 0))
	break;
      wait (0);
#else /* neither BSD_SYSTEM nor UNIPLUS: random sysV */
#ifdef POSIX_SIGNALS    /* would this work for GNU/Linux as well? */
      sigblock (sigmask (SIGCHLD));
      errno = 0;
      if (kill (pid, 0) == -1 && errno == ESRCH)
	{
	  sigunblock (sigmask (SIGCHLD));
	  break;
	}

      sigsuspend (&empty_mask);
#else /* not POSIX_SIGNALS */
#ifdef HAVE_SYSV_SIGPAUSE
      sighold (SIGCHLD);
      if (0 > kill (pid, 0))
	{
	  sigrelse (SIGCHLD);
	  break;
	}
      sigpause (SIGCHLD);
#else /* not HAVE_SYSV_SIGPAUSE */
#ifdef WINDOWSNT
      wait (0);
      break;
#else /* not WINDOWSNT */
      if (0 > kill (pid, 0))
	break;
      /* Using sleep instead of pause avoids timing error.
	 If the inferior dies just before the sleep,
	 we lose just one second.  */
      sleep (1);
#endif /* not WINDOWSNT */
#endif /* not HAVE_SYSV_SIGPAUSE */
#endif /* not POSIX_SIGNALS */
#endif /* not UNIPLUS */
#endif /* not BSD_SYSTEM, and not HPUX version >= 6 */
#endif /* not VMS */
#else /* not subprocesses */
#if __DJGPP__ > 1
      break;
#else /* not __DJGPP__ > 1 */
#ifndef BSD4_1
      if (kill (pid, 0) < 0)
	break;
      wait (0);
#else /* BSD4_1 */
      int status;
      status = wait (0);
      if (status == pid || status == -1)
	break;
#endif /* BSD4_1 */
#endif /* not __DJGPP__ > 1*/
#endif /* not subprocesses */
    }
}

#ifdef subprocesses

/*
 *	flush any pending output
 *      (may flush input as well; it does not matter the way we use it)
 */

void
flush_pending_output (channel)
     int channel;
{
#ifdef HAVE_TERMIOS
  /* If we try this, we get hit with SIGTTIN, because
     the child's tty belongs to the child's pgrp. */
#else
#ifdef TCFLSH
  ioctl (channel, TCFLSH, 1);
#else
#ifdef TIOCFLUSH
  int zero = 0;
  /* 3rd arg should be ignored
     but some 4.2 kernels actually want the address of an int
     and nonzero means something different.  */
  ioctl (channel, TIOCFLUSH, &zero);
#endif
#endif
#endif
}

#ifndef VMS
/*  Set up the terminal at the other end of a pseudo-terminal that
    we will be controlling an inferior through.
    It should not echo or do line-editing, since that is done
    in Emacs.  No padding needed for insertion into an Emacs buffer.  */

void
child_setup_tty (out)
     int out;
{
#ifndef DOS_NT
  struct emacs_tty s;

  EMACS_GET_TTY (out, &s);

#if defined (HAVE_TERMIO) || defined (HAVE_TERMIOS)
  s.main.c_oflag |= OPOST;	/* Enable output postprocessing */
  s.main.c_oflag &= ~ONLCR;	/* Disable map of NL to CR-NL on output */
#ifdef NLDLY
  s.main.c_oflag &= ~(NLDLY|CRDLY|TABDLY|BSDLY|VTDLY|FFDLY);
  				/* No output delays */
#endif
  s.main.c_lflag &= ~ECHO;	/* Disable echo */
  s.main.c_lflag |= ISIG;	/* Enable signals */
#if 0  /* This causes bugs in (for instance) telnet to certain sites.  */
  s.main.c_iflag &= ~ICRNL;	/* Disable map of CR to NL on input */
#ifdef INLCR  /* Just being cautious, since I can't check how
		 widespread INLCR is--rms.  */
  s.main.c_iflag &= ~INLCR;	/* Disable map of NL to CR on input */
#endif
#endif
#ifdef IUCLC
  s.main.c_iflag &= ~IUCLC;	/* Disable downcasing on input.  */
#endif
#ifdef ISTRIP
  s.main.c_iflag &= ~ISTRIP;	/* don't strip 8th bit on input */
#endif
#ifdef OLCUC
  s.main.c_oflag &= ~OLCUC;	/* Disable upcasing on output.  */
#endif
  s.main.c_oflag &= ~TAB3;	/* Disable tab expansion */
  s.main.c_cflag = (s.main.c_cflag & ~CSIZE) | CS8; /* Don't strip 8th bit */
#if 0
  /* Said to be unnecessary:  */
  s.main.c_cc[VMIN] = 1;	/* minimum number of characters to accept  */
  s.main.c_cc[VTIME] = 0;	/* wait forever for at least 1 character  */
#endif

  s.main.c_lflag |= ICANON;	/* Enable erase/kill and eof processing */
  s.main.c_cc[VEOF] = 04;	/* insure that EOF is Control-D */
  s.main.c_cc[VERASE] = CDISABLE;	/* disable erase processing */
  s.main.c_cc[VKILL] = CDISABLE;	/* disable kill processing */

#ifdef HPUX
  s.main.c_cflag = (s.main.c_cflag & ~CBAUD) | B9600; /* baud rate sanity */
#endif /* HPUX */

#ifdef SIGNALS_VIA_CHARACTERS
  /* the QUIT and INTR character are used in process_send_signal
     so set them here to something useful.  */
  if (s.main.c_cc[VQUIT] == CDISABLE)
    s.main.c_cc[VQUIT] = '\\'&037;	/* Control-\ */
  if (s.main.c_cc[VINTR] == CDISABLE)
    s.main.c_cc[VINTR] = 'C'&037;	/* Control-C */
#endif /* not SIGNALS_VIA_CHARACTERS */

#ifdef AIX
/* AIX enhanced edit loses NULs, so disable it */
#ifndef IBMR2AIX
  s.main.c_line = 0;
  s.main.c_iflag &= ~ASCEDIT;
#endif
  /* Also, PTY overloads NUL and BREAK.
     don't ignore break, but don't signal either, so it looks like NUL.  */
  s.main.c_iflag &= ~IGNBRK;
  s.main.c_iflag &= ~BRKINT;
  /* rms: Formerly it set s.main.c_cc[VINTR] to 0377 here
     unconditionally.  Then a SIGNALS_VIA_CHARACTERS conditional
     would force it to 0377.  That looks like duplicated code.  */
#ifndef SIGNALS_VIA_CHARACTERS
  /* QUIT and INTR work better as signals, so disable character forms */
  s.main.c_cc[VQUIT] = CDISABLE;
  s.main.c_cc[VINTR] = CDISABLE;
  s.main.c_lflag &= ~ISIG;
#endif /* no TIOCGPGRP or no TIOCGLTC or no TIOCGETC */
  s.main.c_cc[VEOL] = CDISABLE;
  s.main.c_cflag = (s.main.c_cflag & ~CBAUD) | B9600; /* baud rate sanity */
#endif /* AIX */

#else /* not HAVE_TERMIO */

  s.main.sg_flags &= ~(ECHO | CRMOD | ANYP | ALLDELAY | RAW | LCASE
		       | CBREAK | TANDEM);
  s.main.sg_flags |= LPASS8;
  s.main.sg_erase = 0377;
  s.main.sg_kill = 0377;
  s.lmode = LLITOUT | s.lmode;        /* Don't strip 8th bit */

#endif /* not HAVE_TERMIO */

  EMACS_SET_TTY (out, &s, 0);

#ifdef BSD4_1
  if (interrupt_input)
    reset_sigio ();
#endif /* BSD4_1 */
#ifdef RTU
  {
    int zero = 0;
    ioctl (out, FIOASYNC, &zero);
  }
#endif /* RTU */
#endif /* not DOS_NT */
}
#endif /* not VMS */

#endif /* subprocesses */

/* Record a signal code and the handler for it.  */
struct save_signal
{
  int code;
  SIGTYPE (*handler) P_ ((int));
};

static void save_signal_handlers P_ ((struct save_signal *));
static void restore_signal_handlers P_ ((struct save_signal *));

/* Suspend the Emacs process; give terminal to its superior.  */

void
sys_suspend ()
{
#ifdef VMS
  /* "Foster" parentage allows emacs to return to a subprocess that attached
     to the current emacs as a cheaper than starting a whole new process.  This
     is set up by KEPTEDITOR.COM.  */
  unsigned long parent_id, foster_parent_id;
  char *fpid_string;

  fpid_string = getenv ("EMACS_PARENT_PID");
  if (fpid_string != NULL)
    {
      sscanf (fpid_string, "%x", &foster_parent_id);
      if (foster_parent_id != 0)
	parent_id = foster_parent_id;
      else
	parent_id = getppid ();
    }
  else
    parent_id = getppid ();

  xfree (fpid_string);		/* On VMS, this was malloc'd */

  if (parent_id && parent_id != 0xffffffff)
    {
      SIGTYPE (*oldsig)() = (int) signal (SIGINT, SIG_IGN);
      int status = LIB$ATTACH (&parent_id) & 1;
      signal (SIGINT, oldsig);
      return status;
    }
  else
    {
      struct {
	int	l;
	char	*a;
      } d_prompt;
      d_prompt.l = sizeof ("Emacs: ");		/* Our special prompt */
      d_prompt.a = "Emacs: ";			/* Just a reminder */
      LIB$SPAWN (0, 0, 0, 0, 0, 0, 0, 0, 0, 0, &d_prompt, 0);
      return 1;
    }
  return -1;
#else
#if defined (SIGTSTP) && !defined (MSDOS)

  {
    int pgrp = EMACS_GETPGRP (0);
    EMACS_KILLPG (pgrp, SIGTSTP);
  }

#else /* No SIGTSTP */
#ifdef USG_JOBCTRL /* If you don't know what this is don't mess with it */
  ptrace (0, 0, 0, 0);		/* set for ptrace - caught by csh */
  kill (getpid (), SIGQUIT);

#else /* No SIGTSTP or USG_JOBCTRL */

/* On a system where suspending is not implemented,
   instead fork a subshell and let it talk directly to the terminal
   while we wait.  */
  sys_subshell ();

#endif /* no USG_JOBCTRL */
#endif /* no SIGTSTP */
#endif /* not VMS */
}

/* Fork a subshell.  */

#ifndef MAC_OS8
void
sys_subshell ()
{
#ifndef VMS
#ifdef DOS_NT	/* Demacs 1.1.2 91/10/20 Manabu Higashida */
  int st;
  char oldwd[MAXPATHLEN+1]; /* Fixed length is safe on MSDOS.  */
#endif
  int pid;
  struct save_signal saved_handlers[5];
  Lisp_Object dir;
  unsigned char *str = 0;
  int len;

  saved_handlers[0].code = SIGINT;
  saved_handlers[1].code = SIGQUIT;
  saved_handlers[2].code = SIGTERM;
#ifdef SIGIO
  saved_handlers[3].code = SIGIO;
  saved_handlers[4].code = 0;
#else
  saved_handlers[3].code = 0;
#endif

  /* Mentioning current_buffer->buffer would mean including buffer.h,
     which somehow wedges the hp compiler.  So instead...  */

  dir = intern ("default-directory");
  if (NILP (Fboundp (dir)))
    goto xyzzy;
  dir = Fsymbol_value (dir);
  if (!STRINGP (dir))
    goto xyzzy;

  dir = expand_and_dir_to_file (Funhandled_file_name_directory (dir), Qnil);
  str = (unsigned char *) alloca (SCHARS (dir) + 2);
  len = SCHARS (dir);
  bcopy (SDATA (dir), str, len);
  if (str[len - 1] != '/') str[len++] = '/';
  str[len] = 0;
 xyzzy:

#ifdef DOS_NT
  pid = 0;
#if __DJGPP__ > 1
  save_signal_handlers (saved_handlers);
  synch_process_alive = 1;
#endif /* __DJGPP__ > 1 */
#else
  pid = vfork ();
  if (pid == -1)
    error ("Can't spawn subshell");
#endif

  if (pid == 0)
    {
      char *sh = 0;

#ifdef DOS_NT    /* MW, Aug 1993 */
      getwd (oldwd);
      if (sh == 0)
	sh = (char *) egetenv ("SUSPEND");	/* KFS, 1994-12-14 */
#endif
      if (sh == 0)
	sh = (char *) egetenv ("SHELL");
      if (sh == 0)
	sh = "sh";

      /* Use our buffer's default directory for the subshell.  */
      if (str)
	chdir ((char *) str);

#ifdef subprocesses
      close_process_descs ();	/* Close Emacs's pipes/ptys */
#endif

#ifdef SET_EMACS_PRIORITY
      {
	extern EMACS_INT emacs_priority;

	if (emacs_priority < 0)
	  nice (-emacs_priority);
      }
#endif

#ifdef MSDOS    /* Demacs 1.1.2 91/10/20 Manabu Higashida */
      {
	char *epwd = getenv ("PWD");
	char old_pwd[MAXPATHLEN+1+4];

	/* If PWD is set, pass it with corrected value.  */
	if (epwd)
	  {
	    strcpy (old_pwd, epwd);
	    if (str[len - 1] == '/')
	      str[len - 1] = '\0';
	    setenv ("PWD", str, 1);
	  }
	st = system (sh);
	chdir (oldwd);
	if (epwd)
	  putenv (old_pwd);	/* restore previous value */
      }
#if 0	/* This is also reported if last command executed in subshell failed, KFS */
      if (st)
	report_file_error ("Can't execute subshell", Fcons (build_string (sh), Qnil));
#endif
#else /* not MSDOS */
#ifdef  WINDOWSNT
      /* Waits for process completion */
      pid = _spawnlp (_P_WAIT, sh, sh, NULL);
      chdir (oldwd);
      if (pid == -1)
	write (1, "Can't execute subshell", 22);
#else   /* not WINDOWSNT */
      execlp (sh, sh, (char *) 0);
      write (1, "Can't execute subshell", 22);
      _exit (1);
#endif  /* not WINDOWSNT */
#endif /* not MSDOS */
    }

  /* Do this now if we did not do it before.  */
#if !defined (MSDOS) || __DJGPP__ == 1
  save_signal_handlers (saved_handlers);
  synch_process_alive = 1;
#endif

#ifndef DOS_NT
  wait_for_termination (pid);
#endif
  restore_signal_handlers (saved_handlers);
  synch_process_alive = 0;
#endif /* !VMS */
}
#endif /* !MAC_OS8 */

static void
save_signal_handlers (saved_handlers)
     struct save_signal *saved_handlers;
{
  while (saved_handlers->code)
    {
      saved_handlers->handler
	= (SIGTYPE (*) P_ ((int))) signal (saved_handlers->code, SIG_IGN);
      saved_handlers++;
    }
}

static void
restore_signal_handlers (saved_handlers)
     struct save_signal *saved_handlers;
{
  while (saved_handlers->code)
    {
      signal (saved_handlers->code, saved_handlers->handler);
      saved_handlers++;
    }
}

#ifdef F_SETFL

int old_fcntl_flags;

void
init_sigio (fd)
     int fd;
{
#ifdef FASYNC
  old_fcntl_flags = fcntl (fd, F_GETFL, 0) & ~FASYNC;
  fcntl (fd, F_SETFL, old_fcntl_flags | FASYNC);
#endif
  interrupts_deferred = 0;
}

void
reset_sigio ()
{
  unrequest_sigio ();
}

#ifdef FASYNC		/* F_SETFL does not imply existence of FASYNC */

void