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, 2006, 2007, 2008, 2009, 2010
                 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 3 of the License, 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.  If not, see <http://www.gnu.org/licenses/>.  */

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

#include <ctype.h>
#include <signal.h>
#include <stdio.h>
#include <setjmp.h>
#ifdef HAVE_PWD_H
#include <pwd.h>
#include <grp.h>
#endif /* HAVE_PWD_H */
#ifdef HAVE_LIMITS_H
#include <limits.h>
#endif /* HAVE_LIMITS_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.  */

/* The w32 build defines select stuff in w32.h, which is included by
   sys/select.h (included below).   */
#ifndef WINDOWSNT
#include "sysselect.h"
#endif

#include "blockinput.h"

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

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

#ifdef HAVE_SETPGID
#if !defined (USG)
#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>

extern int etext;
extern unsigned start __asm__ ("start");
#endif

#include <sys/file.h>

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

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

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

#if defined (USG)
#include <sys/utsname.h>
#include <memory.h>
#endif /* USG */

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"
#include "cm.h"  /* for reset_sys_modes */

/* For serial_configure and serial_open.  */
extern Lisp_Object QCport, QCspeed, QCprocess;
extern Lisp_Object QCbytesize, QCstopbits, QCparity, Qodd, Qeven;
extern Lisp_Object QCflowcontrol, Qhw, Qsw, QCsummary;

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

#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

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

#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;

void croak P_ ((char *)) NO_RETURN;

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

SIGMASKTYPE sigprocmask_set;


#if !defined (HAVE_GET_CURRENT_DIR_NAME) || defined (BROKEN_GET_CURRENT_DIR_NAME)

/* Return the current working directory.  Returns NULL on errors.
   Any other returned value must be freed with free. This is used
   only when get_current_dir_name is not defined on the system.  */
char*
get_current_dir_name ()
{
  char *buf;
  char *pwd;
  struct stat dotstat, pwdstat;
  /* If PWD is accurate, use it instead of calling getwd.  PWD is
     sometimes a nicer name, and using it may avoid a fatal error if a
     parent directory is searchable but not readable.  */
    if ((pwd = getenv ("PWD")) != 0
      && (IS_DIRECTORY_SEP (*pwd) || (*pwd && IS_DEVICE_SEP (pwd[1])))
      && stat (pwd, &pwdstat) == 0
      && stat (".", &dotstat) == 0
      && dotstat.st_ino == pwdstat.st_ino
      && dotstat.st_dev == pwdstat.st_dev
#ifdef MAXPATHLEN
      && strlen (pwd) < MAXPATHLEN
#endif
      )
    {
      buf = (char *) malloc (strlen (pwd) + 1);
      if (!buf)
        return NULL;
      strcpy (buf, pwd);
    }
#ifdef HAVE_GETCWD
  else
    {
      size_t buf_size = 1024;
      buf = (char *) malloc (buf_size);
      if (!buf)
        return NULL;
      for (;;)
        {
          if (getcwd (buf, buf_size) == buf)
            break;
          if (errno != ERANGE)
            {
              int tmp_errno = errno;
              free (buf);
              errno = tmp_errno;
              return NULL;
            }
          buf_size *= 2;
          buf = (char *) realloc (buf, buf_size);
          if (!buf)
            return NULL;
        }
    }
#else
  else
    {
      /* We need MAXPATHLEN here.  */
      buf = (char *) malloc (MAXPATHLEN + 1);
      if (!buf)
        return NULL;
      if (getwd (buf) == NULL)
        {
          int tmp_errno = errno;
          free (buf);
          errno = tmp_errno;
          return NULL;
        }
    }
#endif
  return buf;
}
#endif


/* Discard pending input on all input descriptors.  */

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

  if (noninteractive)
    return;

#ifdef MSDOS    /* Demacs 1.1.1 91/10/16 HIRANO Satoshi */
  while (dos_keyread () != -1)
    ;
#else /* not MSDOS */
  {
    struct tty_display_info *tty;
    for (tty = tty_list; tty; tty = tty->next)
      {
        if (tty->input)         /* Is the device suspended? */
          {
            EMACS_GET_TTY (fileno (tty->input), &buf);
            EMACS_SET_TTY (fileno (tty->input), &buf, 0);
          }
      }
  }
#endif /* not MSDOS */
#endif /* not WINDOWSNT */
}


#ifdef SIGTSTP

/* Arrange for character C to be read as the next input from
   the terminal.
   XXX What if we have multiple ttys?
*/

void
stuff_char (char c)
{
  if (! FRAME_TERMCAP_P (SELECTED_FRAME ()))
    return;

/* Should perhaps error if in batch mode */
#ifdef TIOCSTI
  ioctl (fileno (CURTTY()->input), 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 (int fd)
{
  if (noninteractive)
    emacs_ospeed = 0;
  else
    {
#ifdef DOS_NT
    emacs_ospeed = 15;
#else  /* not DOS_NT */
#ifdef HAVE_TERMIOS
      struct termios sg;

      sg.c_cflag = B9600;
      tcgetattr (fd, &sg);
      emacs_ospeed = cfgetospeed (&sg);
#else /* not TERMIOS */
#ifdef HAVE_TERMIO
      struct termio sg;

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

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

  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 ()
{
  croak ("wait_without_blocking");
  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
#if defined (BSD_SYSTEM) || defined (HPUX)
      /* 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 */
#ifdef WINDOWSNT
      wait (0);
      break;
#else /* not WINDOWSNT */
      sigblock (sigmask (SIGCHLD));
      errno = 0;
      if (kill (pid, 0) == -1 && errno == ESRCH)
	{
	  sigunblock (sigmask (SIGCHLD));
	  break;
	}

      sigsuspend (&empty_mask);
#endif /* not WINDOWSNT */
#endif /* not BSD_SYSTEM, and not HPUX version >= 6 */
#else /* not subprocesses */
      break;
#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
}

/*  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
  /* http://lists.gnu.org/archive/html/emacs-devel/2008-05/msg00406.html
     Some versions of GNU Hurd do not have FFDLY?  */
#ifdef FFDLY
  s.main.c_oflag &= ~(NLDLY|CRDLY|TABDLY|BSDLY|VTDLY|FFDLY);
  				/* No output delays */
#else
  s.main.c_oflag &= ~(NLDLY|CRDLY|TABDLY|BSDLY|VTDLY);
  				/* No output delays */
#endif
#endif
  s.main.c_lflag &= ~ECHO;	/* Disable echo */
  s.main.c_lflag |= ISIG;	/* Enable signals */
#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 */
  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
  /* 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.  */
  s.main.c_cflag = (s.main.c_cflag & ~CBAUD) | B9600; /* baud rate sanity */
#endif /* AIX */

  /* We used to enable ICANON (and set VEOF to 04), but this leads to
     problems where process.c wants to send EOFs every once in a while
     to force the output, which leads to weird effects when the
     subprocess has disabled ICANON and ends up seeing those spurious
     extra EOFs.  So we don't send EOFs any more in
     process.c:send_process, and instead we disable ICANON by default,
     so if a subsprocess sets up ICANON, it's his problem (or the Elisp
     package that talks to it) to deal with lines that are too long.  */
  s.main.c_lflag &= ~ICANON;	/* Disable line editing and eof processing */
  s.main.c_cc[VMIN] = 1;
  s.main.c_cc[VTIME] = 0;

#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);

#endif /* not DOS_NT */
}

#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 ()
{
#if defined (SIGTSTP) && !defined (MSDOS)

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

#else /* No SIGTSTP */
/* 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 SIGTSTP */
}

/* Fork a subshell.  */

void
sys_subshell ()
{
#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;
  save_signal_handlers (saved_handlers);
  synch_process_alive = 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 */
      }
#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.  */
#ifndef MSDOS
  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;
}

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++;
    }
}

#ifndef SIGIO
/* If SIGIO is broken, don't do anything. */
void
init_sigio (int fd)
{
}

void
reset_sigio (int fd)
{
}

void
request_sigio (void)
{
}

void
unrequest_sigio (void)
{
}

#else
#ifdef F_SETFL

int old_fcntl_flags[MAXDESC];

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

void
reset_sigio (fd)
     int fd;
{
#ifdef FASYNC
  fcntl (fd, F_SETFL, old_fcntl_flags[fd]);
#endif
}

#ifdef FASYNC		/* F_SETFL does not imply existence of FASYNC */
/* XXX Uhm, FASYNC is not used anymore here. */
/* XXX Yeah, but you need it for SIGIO, don't you? */

void
request_sigio ()
{
  if (noninteractive)
    return;

#ifdef SIGWINCH
  sigunblock (sigmask (SIGWINCH));
#endif
  sigunblock (sigmask (SIGIO));

  interrupts_deferred = 0;
}

void
unrequest_sigio (void)
{ 
  if (noninteractive)
    return;

#if 0 /* XXX What's wrong with blocking SIGIO under X?  */
  if (x_display_list)
    return;
#endif

#ifdef SIGWINCH
  sigblock (sigmask (SIGWINCH));
#endif
  sigblock (sigmask (SIGIO));
  interrupts_deferred = 1;
}

#else /* no FASYNC */
#ifndef MSDOS

void
request_sigio ()
{
  if (noninteractive || read_socket_hook)
    return;

  croak ("request_sigio");
}

void
unrequest_sigio ()
{
  if (noninteractive || read_socket_hook)
    return;

  croak ("unrequest_sigio");
}

#endif /* MSDOS */
#endif /* FASYNC */
#endif /* F_SETFL */
#endif /* SIGIO */


/* Getting and setting emacs_tty structures.  */

/* Set *TC to the parameters associated with the terminal FD.
   Return zero if all's well, or -1 if we ran into an error we
   couldn't deal with.  */
int
emacs_get_tty (fd, settings)
     int fd;
     struct emacs_tty *settings;
{
  /* Retrieve the primary parameters - baud rate, character size, etcetera.  */
#ifdef HAVE_TCATTR
  /* We have those nifty POSIX tcmumbleattr functions.  */
  bzero (&settings->main, sizeof (settings->main));
  if (tcgetattr (fd, &settings->main) < 0)
    return -1;

#else
#ifdef HAVE_TERMIO
  /* The SYSV-style interface?  */
  if (ioctl (fd, TCGETA, &settings->main) < 0)
    return -1;

#else
#ifndef DOS_NT
  /* I give up - I hope you have the BSD ioctls.  */
  if (ioctl (fd, TIOCGETP, &settings->main) < 0)
    return -1;
#endif /* not DOS_NT */
#endif
#endif

  /* Suivant - Do we have to get struct ltchars data?  */
#ifdef HAVE_LTCHARS
  if (ioctl (fd, TIOCGLTC, &settings->ltchars) < 0)
    return -1;
#endif

  /* How about a struct tchars and a wordful of lmode bits?  */
#ifdef HAVE_TCHARS
  if (ioctl (fd, TIOCGETC, &settings->tchars) < 0
      || ioctl (fd, TIOCLGET, &settings->lmode) < 0)
    return -1;
#endif

  /* We have survived the tempest.  */
  return 0;
}


/* Set the parameters of the tty on FD according to the contents of
   *SETTINGS.  If FLUSHP is non-zero, we discard input.
   Return 0 if all went well, and -1 if anything failed.  */