/* Asynchronous subprocess control for GNU Emacs.
   Copyright (C) 1985, 86, 87, 88, 93, 94 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, 675 Mass Ave, Cambridge, MA 02139, USA.  */

#ifdef VMS
#define ALMOST_STATIC		/* marks quantities which could be static were
				   vms's create_process in this file. */
#else
#define ALMOST_STATIC static
#endif

#include <signal.h>

#include <config.h>

/* This file is split into two parts by the following preprocessor
   conditional.  The 'then' clause contains all of the support for
   asynchronous subprocesses.  The 'else' clause contains stub
   versions of some of the asynchronous subprocess routines that are
   often called elsewhere in Emacs, so we don't have to #ifdef the
   sections that call them.  */


#ifdef subprocesses

#include <stdio.h>
#include <errno.h>
#include <setjmp.h>
#include <sys/types.h>		/* some typedefs are used in sys/file.h */
#include <sys/file.h>
#include <sys/stat.h>
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif

#ifdef HAVE_SOCKETS	/* TCP connection support, if kernel can do it */
#ifdef VMS
#if defined(UCX) || defined(NETLIB)
#include <socket.h>
#include <netdb.h>
#include <in.h>
#include <inet.h>
#include <ucx$inetdef.h>
#endif /* UCX */
#ifdef MULTINET
#ifndef __GNUC__
#define __TYPES 1		/* Otherwise, the Multinet types.h is
				   defining time_t, even though it's already
				   defined */
#include "multinet_root:[multinet.include.sys]types.h"
#undef FD_SET    /* we need types for the rest of the multinet includes */
#undef FD_CLR    /* to work with vaxc.  but types makes bogus defns */
#undef FD_ISSET  /* of the FD_* macros... */
#undef FD_ZERO
#endif
#include "multinet_root:[multinet.include.sys]socket.h"
#include "multinet_root:[multinet.include]netdb.h"
#include "multinet_root:[multinet.include.netinet]in.h"
#endif /* MULTINET */
#else /* not VMS */
#include <sys/socket.h>
#include <netdb.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#endif /* VMS */
#endif /* HAVE_SOCKETS */

/* TERM is a poor-man's SLIP, used on Linux.  */
#ifdef TERM
#include <client.h>
#endif

/* On some systems, e.g. DGUX, inet_addr returns a 'struct in_addr'. */
#ifdef HAVE_BROKEN_INET_ADDR
#define IN_ADDR struct in_addr
#define NUMERIC_ADDR_ERROR (numeric_addr.s_addr == -1)
#else
#define IN_ADDR unsigned long
#define NUMERIC_ADDR_ERROR (numeric_addr == -1)
#endif

#if defined(BSD) || defined(STRIDE)
#include <sys/ioctl.h>
#if !defined (O_NDELAY) && defined (HAVE_PTYS) && !defined(USG5)
#include <fcntl.h>
#endif /* HAVE_PTYS and no O_NDELAY */
#endif /* BSD or STRIDE */

#ifdef BROKEN_O_NONBLOCK
#undef O_NONBLOCK
#endif /* BROKEN_O_NONBLOCK */

#ifdef NEED_BSDTTY
#include <bsdtty.h>
#endif

#ifdef IRIS
#include <sys/sysmacros.h>	/* for "minor" */
#endif /* not IRIS */

#include "systime.h"
#include "systty.h"

#include "lisp.h"
#include "window.h"
#include "buffer.h"
#include "process.h"
#include "termhooks.h"
#include "termopts.h"
#include "commands.h"
#include "frame.h"

Lisp_Object Qprocessp;
Lisp_Object Qrun, Qstop, Qsignal, Qopen, Qclosed;
Lisp_Object Qlast_nonmenu_event;
/* Qexit is declared and initialized in eval.c.  */

/* a process object is a network connection when its childp field is neither
   Qt nor Qnil but is instead a string (name of foreign host we
   are connected to + name of port we are connected to) */

#ifdef HAVE_SOCKETS
static Lisp_Object stream_process;

#define NETCONN_P(p) (XGCTYPE (XPROCESS (p)->childp) == Lisp_String)
#else
#define NETCONN_P(p) 0
#endif /* HAVE_SOCKETS */

/* Define first descriptor number available for subprocesses.  */
#ifdef VMS
#define FIRST_PROC_DESC 1
#else /* Not VMS */
#define FIRST_PROC_DESC 3
#endif

/* Define SIGCHLD as an alias for SIGCLD.  There are many conditionals
   testing SIGCHLD.  */

#if !defined (SIGCHLD) && defined (SIGCLD)
#define SIGCHLD SIGCLD
#endif /* SIGCLD */

#include "syssignal.h"

#include "syswait.h"

extern int errno;
extern char *strerror ();

#ifdef VMS
#define err_str(a) ((a != EVMSERR) ? strerror(a) : strerror(a,vaxc$errno))
#else
#define err_str(a) (strerror(a))
#endif

#ifndef HAVE_H_ERRNO
extern int h_errno;
#endif

#ifndef SYS_SIGLIST_DECLARED
#if !defined(BSD4_1) && !defined(VMS)
#ifndef LINUX
extern char *sys_siglist[];
#endif /* not LINUX */
#else /* BSD4_1 or VMS */
char *sys_siglist[] =
  {
    "bum signal!!",
    "hangup",
    "interrupt",
    "quit",
    "illegal instruction",
    "trace trap",
    "iot instruction",
    "emt instruction",
    "floating point exception",
    "kill",
    "bus error",
    "segmentation violation",
    "bad argument to system call",
    "write on a pipe with no one to read it",
    "alarm clock",
    "software termination signal from kill",
    "status signal",
    "sendable stop signal not from tty",
    "stop signal from tty",
    "continue a stopped process",
    "child status has changed",
    "background read attempted from control tty",
    "background write attempted from control tty",
    "input record available at control tty",
    "exceeded CPU time limit",
    "exceeded file size limit"
    };
#endif
#endif /* ! SYS_SIGLIST_DECLARED */

/* t means use pty, nil means use a pipe,
   maybe other values to come.  */
ALMOST_STATIC Lisp_Object Vprocess_connection_type;

#ifdef SKTPAIR
#ifndef HAVE_SOCKETS
#include <sys/socket.h>
#endif
#endif /* SKTPAIR */

/* Number of events of change of status of a process.  */
ALMOST_STATIC int process_tick;

/* Number of events for which the user or sentinel has been notified.  */
static int update_tick;

#ifdef FD_SET
/* We could get this from param.h, but better not to depend on finding that.
   And better not to risk that it might define other symbols used in this
   file.  */
#ifdef FD_SETSIZE
#define MAXDESC FD_SETSIZE
#else
#define MAXDESC 64
#endif
#define SELECT_TYPE fd_set
#else /* no FD_SET */
#define MAXDESC 32
#define SELECT_TYPE int

/* Define the macros to access a single-int bitmap of descriptors.  */
#define FD_SET(n, p) (*(p) |= (1 << (n)))
#define FD_CLR(n, p) (*(p) &= ~(1 << (n)))
#define FD_ISSET(n, p) (*(p) & (1 << (n)))
#define FD_ZERO(p) (*(p) = 0)
#endif /* no FD_SET */

/* If we support X Windows, turn on the code to poll periodically
   to detect C-g.  It isn't actually used when doing interrupt input.  */
#ifdef HAVE_X_WINDOWS
#define POLL_FOR_INPUT
#endif

/* Mask of bits indicating the descriptors that we wait for input on */

ALMOST_STATIC SELECT_TYPE input_wait_mask;

/* The largest descriptor currently in use for a process object.  */
ALMOST_STATIC int max_process_desc;

/* Descriptor to use for keyboard input.  */
static int keyboard_descriptor;

/* Nonzero means delete a process right away if it exits.  */
static int delete_exited_processes;

/* Indexed by descriptor, gives the process (if any) for that descriptor */
Lisp_Object chan_process[MAXDESC];

/* Alist of elements (NAME . PROCESS) */
Lisp_Object Vprocess_alist;

/* On VMS, nonzero means split the status code returned by a subprocess
   into a list of numbers, one for each field in the status code:

     (SEVERITY MESSAGE FACILITY INTERNAL)

   Where those fields correspond to these bits in the status code:

     SEVERITY:  Bits 0-2 contain the severity level of the message.
     MESSAGE:   Bits 3-15 contain the number of the corresponding
                message.
     FACILITY:  Bits 16-27 contain a number for the software component,
                or facility, that generated the message.
     INTERNAL:  Bits 28-31 contain internal control flags.

   There is a routine, do_vms_split_status_code(), which does the split
   for you.  */
int vms_split_status_code;

/* Buffered-ahead input char from process, indexed by channel.
   -1 means empty (no char is buffered).
   Used on sys V where the only way to tell if there is any
   output from the process is to read at least one char.
   Always -1 on systems that support FIONREAD.  */

static int proc_buffered_char[MAXDESC];

static Lisp_Object get_process ();

/* Maximum number of bytes to send to a pty without an eof.  */
static int pty_max_bytes;

/* Compute the Lisp form of the process status, p->status, from
   the numeric status that was returned by `wait'.  */

Lisp_Object status_convert ();

update_status (p)
     struct Lisp_Process *p;
{
  union { int i; WAITTYPE wt; } u;
  u.i = XFASTINT (p->raw_status_low) + (XFASTINT (p->raw_status_high) << 16);
  p->status = status_convert (u.wt);
  p->raw_status_low = Qnil;
  p->raw_status_high = Qnil;
}

/*  Convert a process status word in Unix format to 
    the list that we use internally.  */

Lisp_Object
status_convert (w)
     WAITTYPE w;
{
  if (WIFSTOPPED (w))
    return Fcons (Qstop, Fcons (make_number (WSTOPSIG (w)), Qnil));
  else if (WIFEXITED (w))
    return Fcons (Qexit, Fcons (make_number (WRETCODE (w)),
				WCOREDUMP (w) ? Qt : Qnil));
  else if (WIFSIGNALED (w))
    return Fcons (Qsignal, Fcons (make_number (WTERMSIG (w)),
				  WCOREDUMP (w) ? Qt : Qnil));
  else
    return Qrun;
}

/* Given a status-list, extract the three pieces of information
   and store them individually through the three pointers.  */

void
decode_status (l, symbol, code, coredump)
     Lisp_Object l;
     Lisp_Object *symbol;
     int *code;
     int *coredump;
{
  Lisp_Object tem;

  if (XTYPE (l) == Lisp_Symbol)
    {
      *symbol = l;
      *code = 0;
      *coredump = 0;
    }
  else
    {
      *symbol = XCONS (l)->car;
      tem = XCONS (l)->cdr;
      *code = XFASTINT (XCONS (tem)->car);
      tem = XCONS (tem)->cdr;
      *coredump = !NILP (tem);
    }
}

/* Used with VMS only */
Lisp_Object
do_vms_split_status_code (status)
     unsigned long status;
{
  return Fcons (make_number (status & 7), /* Bits 0-2 */
		Fcons (make_number ((status >> 3)
				    & ((1<<13) - 1)), /* Bits 3-15 */
		       Fcons (make_number ((status >> 16)
					   & ((1<<12) -1)), /* Bits 16-27 */
			      Fcons (make_number ((status >> 28)
						  & ((1<<4) - 1)), /* Bits 28-31 */
				     Qnil))));
}

/* Return a string describing a process status list.  */

Lisp_Object 
status_message (status)
     Lisp_Object status;
{
  Lisp_Object symbol;
  int code, coredump;
  Lisp_Object string, string2;

  decode_status (status, &symbol, &code, &coredump);

  if (EQ (symbol, Qsignal) || EQ (symbol, Qstop))
    {
      char *signame = 0;
      if (code < NSIG)
	signame = sys_siglist[code];
      if (signame == 0)
	signame = "unknown";
      string = build_string (signame);
      string2 = build_string (coredump ? " (core dumped)\n" : "\n");
      XSTRING (string)->data[0] = DOWNCASE (XSTRING (string)->data[0]);
      return concat2 (string, string2);
    }
  else if (EQ (symbol, Qexit))
    {
#ifdef VMS
      if (code & 1)
#else
      if (code == 0)
#endif
	return build_string ("finished\n");
      string = Fnumber_to_string (make_number (code));
      string2 = build_string (coredump ? " (core dumped)\n" : "\n");
      return concat2 (build_string ("exited abnormally with code "),
		      concat2 (string, string2));
    }
  else
    return Fcopy_sequence (Fsymbol_name (symbol));
}

#ifdef HAVE_PTYS

/* Open an available pty, returning a file descriptor.
   Return -1 on failure.
   The file name of the terminal corresponding to the pty
   is left in the variable pty_name.  */

char pty_name[24];

int
allocate_pty ()
{
  struct stat stb;
  register c, i;
  int fd;

  /* Some systems name their pseudoterminals so that there are gaps in
     the usual sequence - for example, on HP9000/S700 systems, there
     are no pseudoterminals with names ending in 'f'.  So we wait for
     three failures in a row before deciding that we've reached the
     end of the ptys.  */
  int failed_count = 0;

#ifdef PTY_ITERATION
  PTY_ITERATION
#else
  for (c = FIRST_PTY_LETTER; c <= 'z'; c++)
    for (i = 0; i < 16; i++)
#endif
      {
#ifdef PTY_NAME_SPRINTF
	PTY_NAME_SPRINTF
#else
	sprintf (pty_name, "/dev/pty%c%x", c, i);
#endif /* no PTY_NAME_SPRINTF */

#ifdef PTY_OPEN
	PTY_OPEN;
#else /* no PTY_OPEN */
#ifdef IRIS
	/* Unusual IRIS code */
 	*ptyv = open ("/dev/ptc", O_RDWR | O_NDELAY, 0);
 	if (fd < 0)
 	  return -1;
	if (fstat (fd, &stb) < 0)
	  return -1;
#else /* not IRIS */
	if (stat (pty_name, &stb) < 0)
	  {
	    failed_count++;
	    if (failed_count >= 3)
	      return -1;
	  }
	else
	  failed_count = 0;
#ifdef O_NONBLOCK
	fd = open (pty_name, O_RDWR | O_NONBLOCK, 0);
#else
	fd = open (pty_name, O_RDWR | O_NDELAY, 0);
#endif
#endif /* not IRIS */
#endif /* no PTY_OPEN */

	if (fd >= 0)
	  {
	    /* check to make certain that both sides are available
	       this avoids a nasty yet stupid bug in rlogins */
#ifdef PTY_TTY_NAME_SPRINTF
	    PTY_TTY_NAME_SPRINTF
#else
            sprintf (pty_name, "/dev/tty%c%x", c, i);
#endif /* no PTY_TTY_NAME_SPRINTF */
#ifndef UNIPLUS
	    if (access (pty_name, 6) != 0)
	      {
		close (fd);
#if !defined(IRIS) && !defined(__sgi)
		continue;
#else
		return -1;
#endif /* IRIS */
	      }
#endif /* not UNIPLUS */
	    setup_pty (fd);
	    return fd;
	  }
      }
  return -1;
}
#endif /* HAVE_PTYS */

Lisp_Object
make_process (name)
     Lisp_Object name;
{
  register Lisp_Object val, tem, name1;
  register struct Lisp_Process *p;
  char suffix[10];
  register int i;
#ifdef VMS
  VMS_PROC_STUFF *get_vms_process_stuff (), *ps;

  ps = get_vms_process_stuff ();
  if (ps == 0)
    error ("Too many VMS processes.");
#endif

  /* size of process structure includes the vector header,
     so deduct for that.  But struct Lisp_Vector includes the first
     element, thus deducts too much, so add it back.  */
  val = Fmake_vector (make_number ((sizeof (struct Lisp_Process)
				    - sizeof (struct Lisp_Vector)
				    + sizeof (Lisp_Object))
				   / sizeof (Lisp_Object)),
		      Qnil);
  XSETTYPE (val, Lisp_Process);

  p = XPROCESS (val);
  XSET (p->infd, Lisp_Int, -1);
  XSET (p->outfd, Lisp_Int, -1);
  XFASTINT (p->pid) = 0;
  XFASTINT (p->tick) = 0;
  XFASTINT (p->update_tick) = 0;
  p->raw_status_low = Qnil;
  p->raw_status_high = Qnil;
  p->status = Qrun;
  p->mark = Fmake_marker ();

  /* If name is already in use, modify it until it is unused.  */

  name1 = name;
  for (i = 1; ; i++)
    {
      tem = Fget_process (name1);
      if (NILP (tem)) break;
      sprintf (suffix, "<%d>", i);
      name1 = concat2 (name, build_string (suffix));
    }
  name = name1;
  p->name = name;
  Vprocess_alist = Fcons (Fcons (name, val), Vprocess_alist);
#ifdef VMS
  ps->process = p;
  ps->translate_p = 1;
  ps->active = 1;
#endif
  return val;
}

remove_process (proc)
     register Lisp_Object proc;
{
  register Lisp_Object pair;

#ifdef VMS
  VMS_PROC_STUFF *vs, *get_vms_process_pointer ();;

  sys$setast (0);
  vs = get_vms_process_pointer (XPROCESS (proc));
  if (vs != 0)
    vs->active = 0;
  sys$setast (1);
#endif /* VMS */

  pair = Frassq (proc, Vprocess_alist);
  Vprocess_alist = Fdelq (pair, Vprocess_alist);
  Fset_marker (XPROCESS (proc)->mark, Qnil, Qnil);

  deactivate_process (proc);
}

DEFUN ("processp", Fprocessp, Sprocessp, 1, 1, 0,
  "Return t if OBJECT is a process.")
  (obj)
     Lisp_Object obj;
{
  return XTYPE (obj) == Lisp_Process ? Qt : Qnil;
}

DEFUN ("get-process", Fget_process, Sget_process, 1, 1, 0,
  "Return the process named NAME, or nil if there is none.")
  (name)
     register Lisp_Object name;
{
  if (XTYPE (name) == Lisp_Process)
    return name;
  CHECK_STRING (name, 0);
  return Fcdr (Fassoc (name, Vprocess_alist));
}

DEFUN ("get-buffer-process", Fget_buffer_process, Sget_buffer_process, 1, 1, 0,
  "Return the (or, a) process associated with BUFFER.\n\
BUFFER may be a buffer or the name of one.")
  (name)
     register Lisp_Object name;
{
  register Lisp_Object buf, tail, proc;

  if (NILP (name)) return Qnil;
  buf = Fget_buffer (name);
  if (NILP (buf)) return Qnil;

  for (tail = Vprocess_alist; !NILP (tail); tail = Fcdr (tail))
    {
      proc = Fcdr (Fcar (tail));
      if (XTYPE (proc) == Lisp_Process && EQ (XPROCESS (proc)->buffer, buf))
	return proc;
    }
  return Qnil;
}

/* This is how commands for the user decode process arguments.  It
   accepts a process, a process name, a buffer, a buffer name, or nil.
   Buffers denote the first process in the buffer, and nil denotes the
   current buffer.  */

static Lisp_Object
get_process (name)
     register Lisp_Object name;
{
  register Lisp_Object proc, obj;
  if (STRINGP (name))
    {
      obj = Fget_process (name);
      if (NILP (obj))
	obj = Fget_buffer (name);
      if (NILP (obj))
	error ("Process %s does not exist", XSTRING (name)->data);
    }
  else if (NILP (name))
    obj = Fcurrent_buffer ();
  else
    obj = name;

  /* Now obj should be either a buffer object or a process object.
   */
  if (BUFFERP (obj))
    {
      proc = Fget_buffer_process (obj);
      if (NILP (proc))
	error ("Buffer %s has no process", XSTRING (XBUFFER (obj)->name)->data);
    }
  else
    {
      CHECK_PROCESS (obj, 0);
      proc = obj;
    }
  return proc;
}

DEFUN ("delete-process", Fdelete_process, Sdelete_process, 1, 1, 0,
  "Delete PROCESS: kill it and forget about it immediately.\n\
PROCESS may be a process, a buffer, the name of a process or buffer, or\n\
nil, indicating the current buffer's process.")
  (proc)
     register Lisp_Object proc;
{
  proc = get_process (proc);
  XPROCESS (proc)->raw_status_low = Qnil;
  XPROCESS (proc)->raw_status_high = Qnil;
  if (NETCONN_P (proc))
    {
      XPROCESS (proc)->status = Fcons (Qexit, Fcons (make_number (0), Qnil));
      XSETINT (XPROCESS (proc)->tick, ++process_tick);
    }
  else if (XINT (XPROCESS (proc)->infd) >= 0)
    {
      Fkill_process (proc, Qnil);
      /* Do this now, since remove_process will make sigchld_handler do nothing.  */
      XPROCESS (proc)->status 
	= Fcons (Qsignal, Fcons (make_number (SIGKILL), Qnil));
      XSETINT (XPROCESS (proc)->tick, ++process_tick);
      status_notify ();
    }
  remove_process (proc);
  return Qnil;
}

DEFUN ("process-status", Fprocess_status, Sprocess_status, 1, 1, 0,
  "Return the status of PROCESS: a symbol, one of these:\n\
run  -- for a process that is running.\n\
stop -- for a process stopped but continuable.\n\
exit -- for a process that has exited.\n\
signal -- for a process that has got a fatal signal.\n\
open -- for a network stream connection that is open.\n\
closed -- for a network stream connection that is closed.\n\
nil -- if arg is a process name and no such process exists.\n\
PROCESS may be a process, a buffer, the name of a process or buffer, or\n\
nil, indicating the current buffer's process.")
  (proc)
     register Lisp_Object proc;
{
  register struct Lisp_Process *p;
  register Lisp_Object status;

  if (STRINGP (proc))
    proc = Fget_process (proc);
  else
    proc = get_process (proc);

  if (NILP (proc))
    return proc;

  p = XPROCESS (proc);
  if (!NILP (p->raw_status_low))
    update_status (p);
  status = p->status;
  if (XTYPE (status) == Lisp_Cons)
    status = XCONS (status)->car;
  if (NETCONN_P (proc))
    {
      if (EQ (status, Qrun))
	status = Qopen;
      else if (EQ (status, Qexit))
	status = Qclosed;
    }
  return status;
}

DEFUN ("process-exit-status", Fprocess_exit_status, Sprocess_exit_status,
       1, 1, 0,
  "Return the exit status of PROCESS or the signal number that killed it.\n\
If PROCESS has not yet exited or died, return 0.")
  (proc)
     register Lisp_Object proc;
{
  CHECK_PROCESS (proc, 0);
  if (!NILP (XPROCESS (proc)->raw_status_low))
    update_status (XPROCESS (proc));
  if (XTYPE (XPROCESS (proc)->status) == Lisp_Cons)
    return XCONS (XCONS (XPROCESS (proc)->status)->cdr)->car;
  return make_number (0);
}

DEFUN ("process-id", Fprocess_id, Sprocess_id, 1, 1, 0,
  "Return the process id of PROCESS.\n\
This is the pid of the Unix process which PROCESS uses or talks to.\n\
For a network connection, this value is nil.")
  (proc)
     register Lisp_Object proc;
{
  CHECK_PROCESS (proc, 0);
  return XPROCESS (proc)->pid;
}

DEFUN ("process-name", Fprocess_name, Sprocess_name, 1, 1, 0,
  "Return the name of PROCESS, as a string.\n\
This is the name of the program invoked in PROCESS,\n\
possibly modified to make it unique among process names.")
  (proc)
     register Lisp_Object proc;
{
  CHECK_PROCESS (proc, 0);
  return XPROCESS (proc)->name;
}

DEFUN ("process-command", Fprocess_command, Sprocess_command, 1, 1, 0,
  "Return the command that was executed to start PROCESS.\n\
This is a list of strings, the first string being the program executed\n\
and the rest of the strings being the arguments given to it.\n\
For a non-child channel, this is nil.")
  (proc)
     register Lisp_Object proc;
{
  CHECK_PROCESS (proc, 0);
  return XPROCESS (proc)->command;
}

DEFUN ("set-process-buffer", Fset_process_buffer, Sset_process_buffer,
  2, 2, 0,
  "Set buffer associated with PROCESS to BUFFER (a buffer, or nil).")
  (proc, buffer)
     register Lisp_Object proc, buffer;
{
  CHECK_PROCESS (proc, 0);
  if (!NILP (buffer))
    CHECK_BUFFER (buffer, 1);
  XPROCESS (proc)->buffer = buffer;
  return buffer;
}

DEFUN ("process-buffer", Fprocess_buffer, Sprocess_buffer,
  1, 1, 0,
  "Return the buffer PROCESS is associated with.\n\
Output from PROCESS is inserted in this buffer\n\
unless PROCESS has a filter.")
  (proc)
     register Lisp_Object proc;
{
  CHECK_PROCESS (proc, 0);
  return XPROCESS (proc)->buffer;
}

DEFUN ("process-mark", Fprocess_mark, Sprocess_mark,
  1, 1, 0,
  "Return the marker for the end of the last output from PROCESS.")
  (proc)
     register Lisp_Object proc;
{
  CHECK_PROCESS (proc, 0);
  return XPROCESS (proc)->mark;
}

DEFUN ("set-process-filter", Fset_process_filter, Sset_process_filter,
  2, 2, 0,
  "Give PROCESS the filter function FILTER; nil means no filter.\n\
t means stop accepting output from the process.\n\
When a process has a filter, each time it does output\n\
the entire string of output is passed to the filter.\n\
The filter gets two arguments: the process and the string of output.\n\
If the process has a filter, its buffer is not used for output.")
  (proc, filter)
     register Lisp_Object proc, filter;
{
  CHECK_PROCESS (proc, 0);
  if (EQ (filter, Qt))
    FD_CLR (XINT (XPROCESS (proc)->infd), &input_wait_mask);
  else if (EQ (XPROCESS (proc)->filter, Qt))
    FD_SET (XINT (XPROCESS (proc)->infd), &input_wait_mask);
  XPROCESS (proc)->filter = filter;
  return filter;
}

DEFUN ("process-filter", Fprocess_filter, Sprocess_filter,
  1, 1, 0,
  "Returns the filter function of PROCESS; nil if none.\n\
See `set-process-filter' for more info on filter functions.")
  (proc)
     register Lisp_Object proc;
{
  CHECK_PROCESS (proc, 0);
  return XPROCESS (proc)->filter;
}

DEFUN ("set-process-sentinel", Fset_process_sentinel, Sset_process_sentinel,
  2, 2, 0,
  "Give PROCESS the sentinel SENTINEL; nil for none.\n\
The sentinel is called as a function when the process changes state.\n\
It gets two arguments: the process, and a string describing the change.")
  (proc, sentinel)
     register Lisp_Object proc, sentinel;
{
  CHECK_PROCESS (proc, 0);
  XPROCESS (proc)->sentinel = sentinel;
  return sentinel;
}

DEFUN ("process-sentinel", Fprocess_sentinel, Sprocess_sentinel,
  1, 1, 0,
  "Return the sentinel of PROCESS; nil if none.\n\
See `set-process-sentinel' for more info on sentinels.")
  (proc)
     register Lisp_Object proc;
{
  CHECK_PROCESS (proc, 0);
  return XPROCESS (proc)->sentinel;
}

DEFUN ("set-process-window-size", Fset_process_window_size,
  Sset_process_window_size, 3, 3, 0,
  "Tell PROCESS that it has logical window size HEIGHT and WIDTH.")
  (proc, height, width)
     register Lisp_Object proc, height, width;
{
  CHECK_PROCESS (proc, 0);
  CHECK_NATNUM (height, 0);
  CHECK_NATNUM (width, 0);
  if (set_window_size (XINT (XPROCESS (proc)->infd),
		       XINT (height), XINT(width)) <= 0)
    return Qnil;
  else
    return Qt;
}

DEFUN ("process-kill-without-query", Fprocess_kill_without_query,
  Sprocess_kill_without_query, 1, 2, 0,
  "Say no query needed if PROCESS is running when Emacs is exited.\n\
Optional second argument if non-nil says to require a query.\n\
Value is t if a query was formerly required.")
  (proc, value)
     register Lisp_Object proc, value;
{
  Lisp_Object tem;

  CHECK_PROCESS (proc, 0);
  tem = XPROCESS (proc)->kill_without_query;
  XPROCESS (proc)->kill_without_query = Fnull (value);

  return Fnull (tem);
}

#if 0 /* Turned off because we don't currently record this info
	 in the process.  Perhaps add it.  */
DEFUN ("process-connection", Fprocess_connection, Sprocess_connection, 1, 1, 0,
 "Return the connection type of `PROCESS'.\n\
The value is `nil' for a pipe,\n\
`t' or `pty' for a pty, or `stream' for a socket connection.")
  (process)
     Lisp_Object process;
{
  return XPROCESS (process)->type;
}
#endif

Lisp_Object
list_processes_1 ()
{
  register Lisp_Object tail, tem;
  Lisp_Object proc, minspace, tem1;
  register struct buffer *old = current_buffer;
  register struct Lisp_Process *p;
  register int state;
  char tembuf[80];

  XFASTINT (minspace) = 1;

  set_buffer_internal (XBUFFER (Vstandard_output));
  Fbuffer_disable_undo (Vstandard_output);

  current_buffer->truncate_lines = Qt;

  write_string ("\
Proc         Status   Buffer         Command\n\
----         ------   ------         -------\n", -1);

  for (tail = Vprocess_alist; !NILP (tail); tail = Fcdr (tail))
    {
      Lisp_Object symbol;

      proc = Fcdr (Fcar (tail));
      p = XPROCESS (proc);
      if (NILP (p->childp))
	continue;

      Finsert (1, &p->name);
      Findent_to (make_number (13), minspace);

      if (!NILP (p->raw_status_low))
	update_status (p);
      symbol = p->status;
      if (XTYPE (p->status) == Lisp_Cons)
	symbol = XCONS (p->status)->car;

      
      if (EQ (symbol, Qsignal))
	{
	  Lisp_Object tem;
	  tem = Fcar (Fcdr (p->status));
#ifdef VMS
	  if (XINT (tem) < NSIG)
	    write_string (strerror (XINT (tem)), -1);
	  else
#endif
	    Fprinc (symbol, Qnil);
	}
      else if (NETCONN_P (proc))
	{
	  if (EQ (symbol, Qrun))
	    write_string ("open", -1);
	  else if (EQ (symbol, Qexit))
	    write_string ("closed", -1);
	  else
	    Fprinc (symbol, Qnil);
	}
      else
	Fprinc (symbol, Qnil);

      if (EQ (symbol, Qexit))
	{
	  Lisp_Object tem;
	  tem = Fcar (Fcdr (p->status));
	  if (XFASTINT (tem))
	    {
	      sprintf (tembuf, " %d", XFASTINT (tem));
	      write_string (tembuf, -1);
	    }
	}

      if (EQ (symbol, Qsignal) || EQ (symbol, Qexit))
	remove_process (proc);

      Findent_to (make_number (22), minspace);
      if (NILP (p->buffer))
	insert_string ("(none)");
      else if (NILP (XBUFFER (p->buffer)->name))
	insert_string ("(Killed)");
      else
	Finsert (1, &XBUFFER (p->buffer)->name);

      Findent_to (make_number (37), minspace);

      if (NETCONN_P (proc))
        {
	  sprintf (tembuf, "(network stream connection to %s)\n",
		   XSTRING (p->childp)->data);
	  insert_string (tembuf);
        }
      else 
	{
	  tem = p->command;
	  while (1)
	    {
	      tem1 = Fcar (tem);
	      Finsert (1, &tem1);
	      tem = Fcdr (tem);
	      if (NILP (tem))
		break;
	      insert_string (" ");
	    }
	  insert_string ("\n");
       }
    }
  return Qnil;
}

DEFUN ("list-processes", Flist_processes, Slist_processes, 0, 0, "",
  "Display a list of all processes.\n\
\(Any processes listed as Exited or Signaled are actually eliminated\n\
after the listing is made.)")
  ()
{
  internal_with_output_to_temp_buffer ("*Process List*",
				       list_processes_1, Qnil);
  return Qnil;
}

DEFUN ("process-list", Fprocess_list, Sprocess_list, 0, 0, 0,
  "Return a list of all processes.")
  ()
{
  return Fmapcar (Qcdr, Vprocess_alist);
}

/* Starting asynchronous inferior processes.  */

static Lisp_Object start_process_unwind ();

DEFUN ("start-process", Fstart_process, Sstart_process, 3, MANY, 0,
  "Start a program in a subprocess.  Return the process object for it.\n\
Args are NAME BUFFER PROGRAM &rest PROGRAM-ARGS\n\
NAME is name for process.  It is modified if necessary to make it unique.\n\
BUFFER is the buffer or (buffer-name) to associate with the process.\n\
 Process output goes at end of that buffer, unless you specify\n\
 an output stream or filter function to handle the output.\n\
 BUFFER may be also nil, meaning that this process is not associated\n\
 with any buffer\n\
Third arg is program file name.  It is searched for as in the shell.\n\
Remaining arguments are strings to give program as arguments.")
  (nargs, args)
     int nargs;
     register Lisp_Object *args;
{
  Lisp_Object buffer, name, program, proc, current_dir, tem;
  register unsigned char **new_argv;
  register int i;
  int count = specpdl_ptr - specpdl;

  buffer = args[1];
  if (!NILP (buffer))
    buffer = Fget_buffer_create (buffer);

  /* Make sure that the child will be able to chdir to the current
     buffer's current directory, or its unhandled equivalent.  We
     can't just have the child check for an error when it does the
     chdir, since it's in a vfork.

     We have to GCPRO around this because Fexpand_file_name and
     Funhandled_file_name_directory might call a file name handling
     function.  The argument list is protected by the caller, so all
     we really have to worry about is buffer.  */
  {
    struct gcpro gcpro1, gcpro2;

    current_dir = current_buffer->directory;

    GCPRO2 (buffer, current_dir);

#ifdef VMS
    current_dir = Funhandled_file_name_directory (current_dir);
    if (NILP (Ffile_accessible_directory_p
	      (expand_and_dir_to_file (current_dir, Qnil))))
      report_file_error ("Setting current directory",
			 Fcons (current_buffer->directory, Qnil));
#else
    current_dir = 
      expand_and_dir_to_file
	(Funhandled_file_name_directory (current_dir), Qnil);
    if (NILP (Ffile_accessible_directory_p (current_dir)))
      report_file_error ("Setting current directory",
			 Fcons (current_buffer->directory, Qnil));
#endif

    UNGCPRO;
  }

  name = args[0];
  CHECK_STRING (name, 0);

  program = args[2];

  CHECK_STRING (program, 2);

  new_argv = (unsigned char **) alloca ((nargs - 1) * sizeof (char *));

#ifndef VMS
  /* If program file name is not absolute, search our path for it */
  if (XSTRING (program)->data[0] != '/')
    {
      struct gcpro gcpro1, gcpro2, gcpro3, gcpro4;

      tem = Qnil;
      GCPRO4 (name, program, buffer, current_dir);
      openp (Vexec_path, program, EXEC_SUFFIXES, &tem, 1);
      UNGCPRO;
      if (NILP (tem))
	report_file_error ("Searching for program", Fcons (program, Qnil));
      new_argv[0] = XSTRING (tem)->data;
    }
  else
    new_argv[0] = XSTRING (program)->data;
#define START 4
#else
  {
    int start = 3;
    CHECK_STRING (args[2], 0);
    if (strcmp (XSTRING (args[2])->data, "*dcl*") == 0
	&& nargs > start + 1)
      {
	CHECK_STRING (args[start], 1);
	if (strcmp (XSTRING (args[start])->data, "-c") == 0)
	  {
	    new_argv[0] = XSTRING (args[2])->data;
	    new_argv[1] = XSTRING (args[start])->data;
	    start++;
	    CHECK_STRING (args[start], start);
	    tem = alloca (XSTRING (args[start])->size + 256);
	    strcpy (tem, XSTRING (args[start])->data);
	    new_argv[2] = hack_vms_program_name (tem);
	    start++;
	  }
      }
    else
      {
	tem = alloca (XSTRING (args[2])->size + 256);
	strcpy (tem, XSTRING (args[2])->data);
	new_argv[0] = hack_vms_program_name (tem);
      }
#define START start
#endif /* not VMS */

  for (i = START; i < nargs; i++)
    {
      tem = args[i];
      CHECK_STRING (tem, i);
      new_argv[i - 2] = XSTRING (tem)->data;
    }
  new_argv[i - 2] = 0;
#ifdef VMS
  }
#endif

  proc = make_process (name);
  /* If an error occurs and we can't start the process, we want to
     remove it from the process list.  This means that each error
     check in create_process doesn't need to call remove_process
     itself; it's all taken care of here.  */
  record_unwind_protect (start_process_unwind, proc);

  XPROCESS (proc)->childp = Qt;
  XPROCESS (proc)->command_channel_p = Qnil;
  XPROCESS (proc)->buffer = buffer;
  XPROCESS (proc)->sentinel = Qnil;
  XPROCESS (proc)->filter = Qnil;
  XPROCESS (proc)->command = Flist (nargs - 2, args + 2);

  create_process (proc, new_argv, current_dir);

  return unbind_to (count, proc);
}

/* This function is the unwind_protect form for Fstart_process.  If
   PROC doesn't have its pid set, then we know someone has signalled
   an error and the process wasn't started successfully, so we should
   remove it from the process list.  */
static Lisp_Object
start_process_unwind (proc)
     Lisp_Object proc;
{
  if (XTYPE (proc) != Lisp_Process)
    abort ();

  /* Was PROC started successfully?  */
#ifdef VMS
  if (XINT (XPROCESS (proc)->pid) == -1)
    remove_process (proc);
#else
  if (XINT (XPROCESS (proc)->pid) <= 0)
    remove_process (proc);
#endif

  return Qnil;
}


SIGTYPE
create_process_1 (signo)
     int signo;
{
#ifdef USG
  /* USG systems forget handlers when they are used;
     must reestablish each time */
  signal (signo, create_process_1);
#endif /* USG */
}

#if 0  /* This doesn't work; see the note before sigchld_handler.  */
#ifdef USG
#ifdef SIGCHLD
/* Mimic blocking of signals on system V, which doesn't really have it.  */

/* Nonzero means we got a SIGCHLD when it was supposed to be blocked.  */
int sigchld_deferred;

SIGTYPE
create_process_sigchld ()
{
  signal (SIGCHLD, create_process_sigchld);

  sigchld_deferred = 1;
}
#endif
#endif
#endif

#ifndef VMS /* VMS version of this function is in vmsproc.c.  */
create_process (process, new_argv, current_dir)
     Lisp_Object process;
     char **new_argv;
     Lisp_Object current_dir;
{
  int pid, inchannel, outchannel, forkin, forkout;
  int sv[2];
#ifdef SIGCHLD
  SIGTYPE (*sigchld)();
#endif
  int pty_flag = 0;
  extern char **environ;

  inchannel = outchannel = -1;

#ifdef HAVE_PTYS
  if (!NILP (Vprocess_connection_type))
    outchannel = inchannel = allocate_pty ();

  if (inchannel >= 0)
    {
#ifndef USG 
      /* On USG systems it does not work to open the pty's tty here
	       and then close and reopen it in the child.  */
#ifdef O_NOCTTY
      /* Don't let this terminal become our controlling terminal
	 (in case we don't have one).  */
      forkout = forkin = open (pty_name, O_RDWR | O_NOCTTY, 0);
#else
      forkout = forkin = open (pty_name, O_RDWR, 0);
#endif
      if (forkin < 0)
	report_file_error ("Opening pty", Qnil);
#else
      forkin = forkout = -1;
#endif /* not USG */
      pty_flag = 1;
    }
  else
#endif /* HAVE_PTYS */
#ifdef SKTPAIR
    {
      if (socketpair (AF_UNIX, SOCK_STREAM, 0, sv) < 0)
	report_file_error ("Opening socketpair", Qnil);
      outchannel = inchannel = sv[0];
      forkout = forkin = sv[1];
    }
#else /* not SKTPAIR */
    {
      pipe (sv);
      inchannel = sv[0];
      forkout = sv[1];
      pipe (sv);
      outchannel = sv[1];
      forkin = sv[0];
    }
#endif /* not SKTPAIR */

#if 0
  /* Replaced by close_process_descs */
  set_exclusive_use (inchannel);
  set_exclusive_use (outchannel);
#endif

/* Stride people say it's a mystery why this is needed
   as well as the O_NDELAY, but that it fails without this.  */
#if defined (STRIDE) || (defined (pfa) && defined (HAVE_PTYS))
  {
    int one = 1;
    ioctl (inchannel, FIONBIO, &one);
  }
#endif

#ifdef O_NONBLOCK
  fcntl (inchannel, F_SETFL, O_NONBLOCK);
#else
#ifdef O_NDELAY
  fcntl (inchannel, F_SETFL, O_NDELAY);
#endif
#endif

  /* Record this as an active process, with its channels.
     As a result, child_setup will close Emacs's side of the pipes.  */
  chan_process[inchannel] = process;
  XSET (XPROCESS (process)->infd, Lisp_Int, inchannel);
  XSET (XPROCESS (process)->outfd, Lisp_Int, outchannel);
  /* Record the tty descriptor used in the subprocess.  */
  if (forkin < 0)
    XPROCESS (process)->subtty = Qnil;
  else
    XFASTINT (XPROCESS (process)->subtty) = forkin;
  XPROCESS (process)->pty_flag = (pty_flag ? Qt : Qnil);
  XPROCESS (process)->status = Qrun;

  /* Delay interrupts until we have a chance to store
     the new fork's pid in its process structure */
#ifdef SIGCHLD
#ifdef BSD4_1
  sighold (SIGCHLD);
#else /* not BSD4_1 */
#if defined (BSD) || defined (UNIPLUS) || defined (HPUX)
  sigsetmask (sigmask (SIGCHLD));
#else /* ordinary USG */
#if 0
  sigchld_deferred = 0;
  sigchld = signal (SIGCHLD, create_process_sigchld);
#endif
#endif /* ordinary USG */
#endif /* not BSD4_1 */
#endif /* SIGCHLD */

  FD_SET (inchannel, &input_wait_mask);
  if (inchannel > max_process_desc)
    max_process_desc = inchannel;

  /* Until we store the proper pid, enable sigchld_handler
     to recognize an unknown pid as standing for this process.
     It is very important not to let this `marker' value stay
     in the table after this function has returned; if it does
     it might cause call-process to hang and subsequent asynchronous
     processes to get their return values scrambled.  */
  XSETINT (XPROCESS (process)->pid, -1);

  {
    /* child_setup must clobber environ on systems with true vfork.
       Protect it from permanent change.  */
    char **save_environ = environ;

    pid = vfork ();
    if (pid == 0)
      {
	int xforkin = forkin;
	int xforkout = forkout;

#if 0 /* This was probably a mistake--it duplicates code later on,
	 but fails to handle all the cases.  */
	/* Make sure SIGCHLD is not blocked in the child.  */
	sigsetmask (SIGEMPTYMASK);
#endif

	/* Make the pty be the controlling terminal of the process.  */
#ifdef HAVE_PTYS
	/* First, disconnect its current controlling terminal.  */
#ifdef HAVE_SETSID
	/* We tried doing setsid only if pty_flag, but it caused
	   process_set_signal to fail on SGI when using a pipe.  */
	setsid ();
	/* Make the pty's terminal the controlling terminal.  */
	if (pty_flag)
	  {
#ifdef TIOCSCTTY
	    /* We ignore the return value
	       because faith@cs.unc.edu says that is necessary on Linux.  */
	    ioctl (xforkin, TIOCSCTTY, 0);
#endif
	  }
#else /* not HAVE_SETSID */
#ifdef USG
	/* It's very important to call setpgrp here and no time
	   afterwards.  Otherwise, we lose our controlling tty which
	   is set when we open the pty. */
	setpgrp ();
#endif /* USG */
#endif /* not HAVE_SETSID */
#if defined (HAVE_TERMIOS) && defined (LDISC1)
	if (pty_flag && xforkin >= 0)
	  {
	    struct termios t;
	    tcgetattr (xforkin, &t);
	    t.c_lflag = LDISC1;
	    if (tcsetattr (xforkin, TCSANOW, &t) < 0)
	      write (1, "create_process/tcsetattr LDISC1 failed\n", 39);
	  }
#else
#if defined (NTTYDISC) && defined (TIOCSETD)
	if (pty_flag && xforkin >= 0)
	  {
	    /* Use new line discipline.  */
	    int ldisc = NTTYDISC;
	    ioctl (xforkin, TIOCSETD, &ldisc);
	  }
#endif
#endif
#ifdef TIOCNOTTY 
	/* In 4.3BSD, the TIOCSPGRP bug has been fixed, and now you
	   can do TIOCSPGRP only to the process's controlling tty.  */
	if (pty_flag)
	  {
	    /* I wonder: would just ioctl (0, TIOCNOTTY, 0) work here? 
	       I can't test it since I don't have 4.3.  */
	    int j = open ("/dev/tty", O_RDWR, 0);
	    ioctl (j, TIOCNOTTY, 0);
	    close (j);
#ifndef USG
	    /* In order to get a controlling terminal on some versions
	       of BSD, it is necessary to put the process in pgrp 0
	       before it opens the terminal.  */
	    setpgrp (0, 0);
#endif
	  }
#endif /* TIOCNOTTY */

#if !defined (RTU) && !defined (UNIPLUS)
/*** There is a suggestion that this ought to be a
     conditional on TIOCSPGRP.  */
	/* Now close the pty (if we had it open) and reopen it.
	   This makes the pty the controlling terminal of the subprocess.  */
	if (pty_flag)
	  {
#ifdef SET_CHILD_PTY_PGRP
	    int pgrp = getpid ();
#endif

	    /* I wonder if close (open (pty_name, ...)) would work?  */
	    if (xforkin >= 0)
	      close (xforkin);
	    xforkout = xforkin = open (pty_name, O_RDWR, 0);

#ifdef SET_CHILD_PTY_PGRP
	    ioctl (xforkin, TIOCSPGRP, &pgrp);
	    ioctl (xforkout, TIOCSPGRP, &pgrp);
#endif

	    if (xforkin < 0)
	      abort ();
	  }
#endif /* not UNIPLUS and not RTU */
#ifdef SETUP_SLAVE_PTY
	if (pty_flag)
	  {
	    SETUP_SLAVE_PTY;
	  }
#endif /* SETUP_SLAVE_PTY */
#ifdef AIX
	/* On AIX, we've disabled SIGHUP above once we start a child on a pty.
	   Now reenable it in the child, so it will die when we want it to.  */
	if (pty_flag)
	  signal (SIGHUP, SIG_DFL);
#endif
#endif /* HAVE_PTYS */

#ifdef SIGCHLD
#ifdef BSD4_1
	sigrelse (SIGCHLD);
#else /* not BSD4_1 */
#if defined (BSD) || defined (UNIPLUS) || defined (HPUX)
	sigsetmask (SIGEMPTYMASK);
#else /* ordinary USG */
#if 0
	signal (SIGCHLD, sigchld);
#endif
#endif /* ordinary USG */
#endif /* not BSD4_1 */
#endif /* SIGCHLD */

	signal (SIGINT, SIG_DFL);
	signal (SIGQUIT, SIG_DFL);

	if (pty_flag)
	  child_setup_tty (xforkout);
	child_setup (xforkin, xforkout, xforkout,
		     new_argv, 1, current_dir);
      }
    environ = save_environ;
  }

  if (pid < 0)
    {
      if (forkin >= 0)
	close (forkin);
      if (forkin != forkout && forkout >= 0)
	close (forkout);
      report_file_error ("Doing vfork", Qnil);
    }
  
  XFASTINT (XPROCESS (process)->pid) = pid;

  /* If the subfork execv fails, and it exits,
     this close hangs.  I don't know why.
     So have an interrupt jar it loose.  */
  stop_polling ();
  signal (SIGALRM, create_process_1);
  alarm (1);
  XPROCESS (process)->subtty = Qnil;
  if (forkin >= 0)
    close (forkin);
  alarm (0);
  start_polling ();
  if (forkin != forkout && forkout >= 0)
    close (forkout);

#ifdef SIGCHLD
#ifdef BSD4_1
  sigrelse (SIGCHLD);
#else /* not BSD4_1 */
#if defined (BSD) || defined (UNIPLUS) || defined (HPUX)
  sigsetmask (SIGEMPTYMASK);
#else /* ordinary USG */
#if 0
  signal (SIGCHLD, sigchld);
  /* Now really handle any of these signals
     that came in during this function.  */
  if (sigchld_deferred)
    kill (getpid (), SIGCHLD);
#endif
#endif /* ordinary USG */
#endif /* not BSD4_1 */
#endif /* SIGCHLD */
}
#endif /* not VMS */

#ifdef HAVE_SOCKETS

/* open a TCP network connection to a given HOST/SERVICE.  Treated
   exactly like a normal process when reading and writing.  Only
   differences are in status display and process deletion.  A network
   connection has no PID; you cannot signal it.  All you can do is
   deactivate and close it via delete-process */

DEFUN ("open-network-stream", Fopen_network_stream, Sopen_network_stream, 
       4, 4, 0, 
  "Open a TCP connection for a service to a host.\n\
Returns a subprocess-object to represent the connection.\n\
Input and output work as for subprocesses; `delete-process' closes it.\n\
Args are NAME BUFFER HOST SERVICE.\n\
NAME is name for process.  It is modified if necessary to make it unique.\n\
BUFFER is the buffer (or buffer-name) to associate with the process.\n\
 Process output goes at end of that buffer, unless you specify\n\
 an output stream or filter function to handle the output.\n\
 BUFFER may be also nil, meaning that this process is not associated\n\
 with any buffer\n\
Third arg is name of the host to connect to, or its IP address.\n\
Fourth arg SERVICE is name of the service desired, or an integer\n\
 specifying a port number to connect to.")
   (name, buffer, host, service)
      Lisp_Object name, buffer, host, service;
{
  Lisp_Object proc;
  register int i;
  struct sockaddr_in address;
  struct servent *svc_info;
  struct hostent *host_info_ptr, host_info;
  char *(addr_list[2]);
  IN_ADDR numeric_addr;
  int s, outch, inch;
  char errstring[80];
  int port;
  struct hostent host_info_fixed;
  struct gcpro gcpro1, gcpro2, gcpro3, gcpro4;
  int retry = 0;
  int count = specpdl_ptr - specpdl;

  GCPRO4 (name, buffer, host, service);
  CHECK_STRING (name, 0);
  CHECK_STRING (host, 0);
  if (XTYPE (service) == Lisp_Int)
    port = htons ((unsigned short) XINT (service));
  else
    {
      CHECK_STRING (service, 0);
      svc_info = getservbyname (XSTRING (service)->data, "tcp");
      if (svc_info == 0)
	error ("Unknown service \"%s\"", XSTRING (service)->data);
#ifdef VMS
      /* So far, getservbyname exists as an entry, but not in reality.
	 As long as it stays this way, it returns -1. */
      if (svc_info == (struct servent *)(-1))
	error ("VMS can't handle named services (\"%s\"). Please use a numeric one.", XSTRING (service)->data);
#endif
      port = svc_info->s_port;
    }

#ifndef TERM
  while (1)
    {
#ifdef TRY_AGAIN
#ifdef HAVE_H_ERRNO
      h_errno = 0;
#endif
#endif
      host_info_ptr = gethostbyname (XSTRING (host)->data);
#ifdef TRY_AGAIN
#ifdef HAVE_H_ERRNO
      if (! (host_info_ptr == 0 && h_errno == TRY_AGAIN))
#endif
#endif
	break;
      Fsleep_for (make_number (1), Qnil);
    }
  if (host_info_ptr == 0)
    /* Attempt to interpret host as numeric inet address */
    {
      numeric_addr = inet_addr ((char *) XSTRING (host)->data);
      if (NUMERIC_ADDR_ERROR)
	error ("Unknown host \"%s\"", XSTRING (host)->data);

      host_info_ptr = &host_info;
      host_info.h_name = 0;
      host_info.h_aliases = 0;
      host_info.h_addrtype = AF_INET;
#ifdef h_addr
      /* Older machines have only one address slot called h_addr.
	 Newer machines have h_addr_list, but #define h_addr to
	 be its first element.  */
      host_info.h_addr_list = &(addr_list[0]);
#endif
      host_info.h_addr = (char*)(&numeric_addr);
      addr_list[1] = 0;
      host_info.h_length = strlen (addr_list[0]);
    }

  bzero (&address, sizeof address);
  bcopy (host_info_ptr->h_addr, (char *) &address.sin_addr,
	 host_info_ptr->h_length);
  address.sin_family = host_info_ptr->h_addrtype;
  address.sin_port = port;

  s = socket (host_info_ptr->h_addrtype, SOCK_STREAM, 0);
  if (s < 0) 
    report_file_error ("error creating socket", Fcons (name, Qnil));

  /* Kernel bugs (on Ultrix at least) cause lossage (not just EINTR)
     when connect is interrupted.  So let's not let it get interrupted.
     Note we do not turn off polling, because polling is only used
     when not interrupt_input, and thus not normally used on the systems
     which have this bug.  On systems which use polling, there's no way
     to quit if polling is turned off.  */
  if (interrupt_input)
    unrequest_sigio ();

  /* Slow down polling to every ten seconds.
     Some kernels have a bug which causes retrying connect to fail
     after a connect.  */
#ifdef POLL_FOR_INPUT
  bind_polling_period (10);
#endif

 loop:
  if (connect (s, (struct sockaddr *) &address, sizeof address) == -1
      && errno != EISCONN)
    {
      int xerrno = errno;

      if (errno == EINTR)
	goto loop;
      if (errno == EADDRINUSE && retry < 20)
	{
	  retry++;
	  goto loop;
	}

#ifdef VMS
      socket_close (s);
#else
      close (s);
#endif

      if (interrupt_input)
	request_sigio ();

      errno = xerrno;
      report_file_error ("connection failed",
			 Fcons (host, Fcons (name, Qnil)));
    }

#ifdef POLL_FOR_INPUT
  unbind_to (count, Qnil);
#endif

  if (interrupt_input)
    request_sigio ();

#else /* TERM */
  s = connect_server (0);
  if (s < 0)
    report_file_error ("error creating socket", Fcons (name, Qnil));
  send_command (s, C_PORT, 0, "%s:%d", XSTRING (host)->data, ntohs (port));
  send_command (s, C_DUMB, 1, 0);
#endif /* TERM */

#ifdef VMS
  {
    int fds[2];
    if (vms_net_chan (s, fds) < 0)
      report_file_error ("error starting I/O on socket", Fcons (name, Qnil));
    inch = fds[0];
    outch = fds[1];
  }
#else /* not VMS */
  inch = s;
  outch = dup (s);
  if (outch < 0) 
    report_file_error ("error duplicating socket", Fcons (name, Qnil));
#endif /* not VMS */

  if (!NILP (buffer))
    buffer = Fget_buffer_create (buffer);
  proc = make_process (name);

  chan_process[inch] = proc;

#ifndef VMS
#ifdef O_NONBLOCK
  fcntl (inch, F_SETFL, O_NONBLOCK);
#else
#ifdef O_NDELAY
  fcntl (inch, F_SETFL, O_NDELAY);
#endif
#endif
#endif /* not VMS */

  XPROCESS (proc)->childp = host;
  XPROCESS (proc)->command_channel_p = Qnil;
  XPROCESS (proc)->buffer = buffer;
  XPROCESS (proc)->sentinel = Qnil;
  XPROCESS (proc)->filter = Qnil;
  XPROCESS (proc)->command = Qnil;
  XPROCESS (proc)->pid = Qnil;
  XSET (XPROCESS (proc)->infd, Lisp_Int, inch);
  XSET (XPROCESS (proc)->outfd, Lisp_Int, outch);
  XPROCESS (proc)->status = Qrun;
  FD_SET (inch, &input_wait_mask);
  if (inch > max_process_desc)
    max_process_desc = inch;

  UNGCPRO;
  return proc;
}
#endif	/* HAVE_SOCKETS */

deactivate_process (proc)
     Lisp_Object proc;
{
  register int inchannel, outchannel;
  register struct Lisp_Process *p = XPROCESS (proc);

  inchannel = XINT (p->infd);
  outchannel = XINT (p->outfd);

  if (inchannel >= 0)
    {
      /* Beware SIGCHLD hereabouts. */
      flush_pending_output (inchannel);
#ifdef VMS
      {
	VMS_PROC_STUFF *get_vms_process_pointer (), *vs;
	extern give_back_vms_process_stuff ();

	vms_close_fd (inchannel);
	if (outchannel != inchannel)
	  vms_close_fd (outchannel);
	vs = get_vms_process_pointer (p);
	if (vs == 0)
	  error ("Could not deactivate process: %x",
		 (getpid () & 0xff000000) | p->pid);
	give_back_vms_process_stuff (vs);
      }
#else
      close (inchannel);
      if (outchannel >= 0 && outchannel != inchannel)
 	close (outchannel);
#endif

      XSET (p->infd, Lisp_Int, -1);
      XSET (p->outfd, Lisp_Int, -1);
      chan_process[inchannel] = Qnil;
      FD_CLR (inchannel, &input_wait_mask);
      if (inchannel == max_process_desc)
	{
	  int i;
	  /* We just closed the highest-numbered process input descriptor,
	     so recompute the highest-numbered one now.  */
	  max_process_desc = 0;
	  for (i = 0; i < MAXDESC; i++)
	    if (!NILP (chan_process[i]))
	      max_process_desc = i;
	}
    }
}

/* Close all descriptors currently in use for communication
   with subprocess.  This is used in a newly-forked subprocess
   to get rid of irrelevant descriptors.  */

close_process_descs ()
{
  int i;
  for (i = 0; i < MAXDESC; i++)
    {
      Lisp_Object process;
      process = chan_process[i];
      if (!NILP (process))
	{
	  int in = XINT (XPROCESS (process)->infd);
	  int out = XINT (XPROCESS (process)->outfd);
#ifdef VMS
	  if (in >= 0)
	    vms_close_fd (in);
	  if (out >= 0 && in != out)
	    vms_close_fd (out);
#else
	  if (in >= 0)
	    close (in);
	  if (out >= 0 && in != out)
	    close (out);
#endif
	}
    }
}

DEFUN ("accept-process-output", Faccept_process_output, Saccept_process_output,
  0, 3, 0,
  "Allow any pending output from subprocesses to be read by Emacs.\n\
It is read into the process' buffers or given to their filter functions.\n\
Non-nil arg PROCESS means do not return until some output has been received\n\
from PROCESS.\n\
Non-nil second arg TIMEOUT and third arg TIMEOUT-MSECS are number of\n\
seconds and microseconds to wait; return after that much time whether\n\
or not there is input.\n\
Return non-nil iff we received any output before the timeout expired.")
  (proc, timeout, timeout_msecs)
     register Lisp_Object proc, timeout, timeout_msecs;
{
  int seconds;
  int useconds;

  if (! NILP (timeout_msecs))
    {
      CHECK_NUMBER (timeout_msecs, 2);
      useconds = XINT (timeout_msecs);
      if (XTYPE (timeout) != Lisp_Int)
	XSET (timeout, Lisp_Int, 0);

      {
	int carry = useconds / 1000000;

	XSETINT (timeout, XINT (timeout) + carry);
	useconds -= carry * 1000000;

	/* I think this clause is necessary because C doesn't
	   guarantee a particular rounding direction for negative
	   integers.  */
	if (useconds < 0)
	  {
	    XSETINT (timeout, XINT (timeout) - 1);
	    useconds += 1000000;
	  }
      }
    }
  else
    useconds = 0;

  if (! NILP (timeout))
    {
      CHECK_NUMBER (timeout, 1);
      seconds = XINT (timeout);
      if (seconds <= 0)
	seconds = -1;
    }
  else
    {
      if (NILP (proc))
	seconds = -1;
      else
	seconds = 0;
    }

  if (NILP (proc))
    XFASTINT (proc) = 0;

  return
    (wait_reading_process_input (seconds, useconds, proc, 0)
     ? Qt : Qnil);
}

/* This variable is different from waiting_for_input in keyboard.c.
   It is used to communicate to a lisp process-filter/sentinel (via the
   function Fwaiting_for_user_input_p below) whether emacs was waiting
   for user-input when that process-filter was called.
   waiting_for_input cannot be used as that is by definition 0 when
   lisp code is being evalled.
   This is also used in record_asynch_buffer_change.
   For that purpose, this must be 0
   when not inside wait_reading_process_input.  */
static int waiting_for_user_input_p;

/* Read and dispose of subprocess output while waiting for timeout to
   elapse and/or keyboard input to be available.

   TIME_LIMIT is:
     timeout in seconds, or
     zero for no limit, or
     -1 means gobble data immediately available but don't wait for any.

   MICROSECS is:
     an additional duration to wait, measured in microseconds.
     If this is nonzero and time_limit is 0, then the timeout
     consists of MICROSECS only.

   READ_KBD is a lisp value:
     0 to ignore keyboard input, or
     1 to return when input is available, or
     -1 meaning caller will actually read the input, so don't throw to
       the quit handler, or
     a cons cell, meaning wait until its car is non-nil
       (and gobble terminal input into the buffer if any arrives), or
     a process object, meaning wait until something arrives from that
       process.  The return value is true iff we read some input from
       that process.

   DO_DISPLAY != 0 means redisplay should be done to show subprocess
   output that arrives.

   If READ_KBD is a pointer to a struct Lisp_Process, then the
     function returns true iff we received input from that process
     before the timeout elapsed.
   Otherwise, return true iff we received input from any process.  */

wait_reading_process_input (time_limit, microsecs, read_kbd, do_display)
     int time_limit, microsecs;
     Lisp_Object read_kbd;
     int do_display;
{
  register int channel, nfds, m;
  static SELECT_TYPE Available;
  int xerrno;
#ifdef VMS
  int xvaxc$errno;
#endif
  Lisp_Object proc;
  EMACS_TIME timeout, end_time, garbage;
  SELECT_TYPE Atemp;
  int wait_channel = -1;
  struct Lisp_Process *wait_proc = 0;
  int got_some_input = 0;
  Lisp_Object *wait_for_cell = 0;

  FD_ZERO (&Available);

  /* If read_kbd is a process to watch, set wait_proc and wait_channel
     accordingly.  */
  if (XTYPE (read_kbd) == Lisp_Process)
    {
      wait_proc = XPROCESS (read_kbd);
      wait_channel = XINT (wait_proc->infd);
      XFASTINT (read_kbd) = 0;
    }

  /* If waiting for non-nil in a cell, record where.  */
  if (XTYPE (read_kbd) == Lisp_Cons)
    {
      wait_for_cell = &XCONS (read_kbd)->car;
      XFASTINT (read_kbd) = 0;
    }

  waiting_for_user_input_p = XINT (read_kbd);

  /* Since we may need to wait several times,
     compute the absolute time to return at.  */
  if (time_limit || microsecs)
    {
      EMACS_GET_TIME (end_time);
      EMACS_SET_SECS_USECS (timeout, time_limit, microsecs);
      EMACS_ADD_TIME (end_time, end_time, timeout);
    }

  /* It would not be safe to call this below,
     where we call redisplay_preserve_echo_area.  */
  if (do_display && frame_garbaged)
    prepare_menu_bars ();

  while (1)
    {
      /* If calling from keyboard input, do not quit
	 since we want to return C-g as an input character.
	 Otherwise, do pending quit if requested.  */
      if (XINT (read_kbd) >= 0)
	QUIT;

      /* Exit now if the cell we're waiting for became non-nil.  */
      if (wait_for_cell && ! NILP (*wait_for_cell))
	break;

      /* Compute time from now till when time limit is up */
      /* Exit if already run out */
      if (time_limit == -1)
	{
	  /* -1 specified for timeout means
	     gobble output available now
	     but don't wait at all. */

	  EMACS_SET_SECS_USECS (timeout, 0, 0);
	}
      else if (time_limit || microsecs)
	{
	  EMACS_GET_TIME (timeout);
	  EMACS_SUB_TIME (timeout, end_time, timeout);
	  if (EMACS_TIME_NEG_P (timeout))
	    break;
	}
      else
	{
	  EMACS_SET_SECS_USECS (timeout, 100000, 0);
	}

      /* Cause C-g and alarm signals to take immediate action,
	 and cause input available signals to zero out timeout.

	 It is important that we do this before checking for process
	 activity.  If we get a SIGCHLD after the explicit checks for
	 process activity, timeout is the only way we will know.  */
      if (XINT (read_kbd) < 0)
	set_waiting_for_input (&timeout);

      /* If status of something has changed, and no input is
	 available, notify the user of the change right away.  After
	 this explicit check, we'll let the SIGCHLD handler zap
	 timeout to get our attention.  */
      if (update_tick != process_tick && do_display)
	{
	  Atemp = input_wait_mask;
	  EMACS_SET_SECS_USECS (timeout, 0, 0);
	  if (select (MAXDESC, &Atemp, 0, 0, &timeout) <= 0)
	    {
	      /* It's okay for us to do this and then continue with
		 the loop, since timeout has already been zeroed out.  */
	      clear_waiting_for_input ();
	      status_notify ();
	    }
	}

      /* Don't wait for output from a non-running process.  */
      if (wait_proc != 0 && !NILP (wait_proc->raw_status_low))
	update_status (wait_proc);
      if (wait_proc != 0
	  && ! EQ (wait_proc->status, Qrun))
	{
	  clear_waiting_for_input ();
	  break;
	}

      /* Wait till there is something to do */

      Available = input_wait_mask;
      if (! XINT (read_kbd) && wait_for_cell == 0)
	FD_CLR (keyboard_descriptor, &Available);

      /* If frame size has changed or the window is newly mapped,
	 redisplay now, before we start to wait.  There is a race
	 condition here; if a SIGIO arrives between now and the select
	 and indicates that a frame is trashed, the select may block
	 displaying a trashed screen.  */
      if (frame_garbaged && do_display)
	redisplay_preserve_echo_area ();

      if (XINT (read_kbd) && detect_input_pending ())
	{
	  nfds = 0;
	  FD_ZERO (&Available);
	}
      else
	nfds = select (MAXDESC, &Available, 0, 0, &timeout);

      xerrno = errno;
#ifdef VMS
      xvaxc$errno = vaxc$errno;
#endif

      /* Make C-g and alarm signals set flags again */
      clear_waiting_for_input ();

      /*  If we woke up due to SIGWINCH, actually change size now.  */
      do_pending_window_change ();

      if (time_limit && nfds == 0) /* timeout elapsed */
	break;
      if (nfds < 0)
	{
	  if (xerrno == EINTR)
	    FD_ZERO (&Available);
#ifdef ultrix
	  /* Ultrix select seems to return ENOMEM when it is
	     interrupted.  Treat it just like EINTR.  Bleah.  Note
	     that we want to test for the "ultrix" CPP symbol, not
	     "__ultrix__"; the latter is only defined under GCC, but
	     not by DEC's bundled CC.  -JimB  */
	  else if (xerrno == ENOMEM)
	    FD_ZERO (&Available);
#endif
#ifdef ALLIANT
	  /* This happens for no known reason on ALLIANT.
	     I am guessing that this is the right response. -- RMS.  */
	  else if (xerrno == EFAULT)
	    FD_ZERO (&Available);
#endif
	  else if (xerrno == EBADF)
	    {
#ifdef AIX
	      /* AIX doesn't handle PTY closure the same way BSD does.  On AIX,
		 the child's closure of the pts gives the parent a SIGHUP, and
		 the ptc file descriptor is automatically closed,
		 yielding EBADF here or at select() call above.
		 So, SIGHUP is ignored (see def of PTY_TTY_NAME_SPRINTF
		 in m/ibmrt-aix.h), and here we just ignore the select error.
		 Cleanup occurs c/o status_notify after SIGCLD. */
	      FD_ZERO (&Available); /* Cannot depend on values returned */
#else
	      abort ();
#endif
	    }
	  else
	    error("select error: %s", err_str (xerrno));
	}
#if defined(sun) && !defined(USG5_4)
      else if (nfds > 0 && FD_ISSET (keyboard_descriptor, &Available)
	       && interrupt_input)
	/* System sometimes fails to deliver SIGIO.

	   David J. Mackenzie says that Emacs doesn't compile under
	   Solaris if this code is enabled, thus the USG5_4 in the CPP
	   conditional.  "I haven't noticed any ill effects so far.
	   If you find a Solaris expert somewhere, they might know
	   better." */
	kill (getpid (), SIGIO);
#endif

      /* Check for keyboard input */
      /* If there is any, return immediately
	 to give it higher priority than subprocesses */

      /* We used to do this if wait_for_cell,
	 but that caused infinite recursion in selection request events.  */
      if ((XINT (read_kbd) || wait_for_cell)
	  && detect_input_pending ())
	{
	  swallow_events ();
	  if (detect_input_pending ())
	    break;
	}

      /* Exit now if the cell we're waiting for became non-nil.  */
      if (wait_for_cell && ! NILP (*wait_for_cell))
	break;

#ifdef SIGIO
      /* If we think we have keyboard input waiting, but didn't get SIGIO
	 go read it.  This can happen with X on BSD after logging out.
	 In that case, there really is no input and no SIGIO,
	 but select says there is input.  */

      if (XINT (read_kbd) && interrupt_input
	  && (FD_ISSET (keyboard_descriptor, &Available)))
	kill (0, SIGIO);
#endif

      if (! wait_proc)
	got_some_input |= nfds > 0;

      /* If checking input just got us a size-change event from X,
	 obey it now if we should.  */
      if (XINT (read_kbd) || wait_for_cell)
	do_pending_window_change ();

      /* Check for data from a process.  */
      /* Really FIRST_PROC_DESC should be 0 on Unix,
	 but this is safer in the short run.  */
      for (channel = keyboard_descriptor == 0 ? FIRST_PROC_DESC : 0;
	   channel <= max_process_desc; channel++)
	{
	  if (FD_ISSET (channel, &Available))
	    {
	      int nread;

	      /* If waiting for this channel, arrange to return as
		 soon as no more input to be processed.  No more
		 waiting.  */
	      if (wait_channel == channel)
		{
		  wait_channel = -1;
		  time_limit = -1;
		  got_some_input = 1;
		}
	      proc = chan_process[channel];
	      if (NILP (proc))
		continue;

	      /* Read data from the process, starting with our
		 buffered-ahead character if we have one.  */

	      nread = read_process_output (proc, channel);
	      if (nread > 0)
		{
		  /* Since read_process_output can run a filter,
		     which can call accept-process-output,
		     don't try to read from any other processes
		     before doing the select again.  */
		  FD_ZERO (&Available);

		  if (do_display)
		    redisplay_preserve_echo_area ();
		}
#ifdef EWOULDBLOCK
	      else if (nread == -1 && errno == EWOULDBLOCK)
		;
#else
#ifdef O_NONBLOCK
	      else if (nread == -1 && errno == EAGAIN)
		;
#else
#ifdef O_NDELAY
	      else if (nread == -1 && errno == EAGAIN)
		;
	      /* Note that we cannot distinguish between no input
		 available now and a closed pipe.
		 With luck, a closed pipe will be accompanied by
		 subprocess termination and SIGCHLD.  */
	      else if (nread == 0 && !NETCONN_P (proc))
		;
#endif				/* O_NDELAY */
#endif				/* O_NONBLOCK */
#endif				/* EWOULDBLOCK */
#ifdef HAVE_PTYS
	      /* On some OSs with ptys, when the process on one end of
		 a pty exits, the other end gets an error reading with
		 errno = EIO instead of getting an EOF (0 bytes read).
		 Therefore, if we get an error reading and errno =
		 EIO, just continue, because the child process has
		 exited and should clean itself up soon (e.g. when we
		 get a SIGCHLD). */
	      else if (nread == -1 && errno == EIO)
		;
#endif				/* HAVE_PTYS */
	      /* If we can detect process termination, don't consider the process
		 gone just because its pipe is closed.  */
#ifdef SIGCHLD
	      else if (nread == 0 && !NETCONN_P (proc))
		;
#endif
	      else
		{
		  /* Preserve status of processes already terminated.  */
		  XSETINT (XPROCESS (proc)->tick, ++process_tick);
		  deactivate_process (proc);
		  if (!NILP (XPROCESS (proc)->raw_status_low))
		    update_status (XPROCESS (proc));
		  if (EQ (XPROCESS (proc)->status, Qrun))
		    XPROCESS (proc)->status
		      = Fcons (Qexit, Fcons (make_number (256), Qnil));
		}
	    }
	}			/* end for each file descriptor */
    }				/* end while exit conditions not met */

  waiting_for_user_input_p = 0;

  /* If calling from keyboard input, do not quit
     since we want to return C-g as an input character.
     Otherwise, do pending quit if requested.  */
  if (XINT (read_kbd) >= 0)
    {
      /* Prevent input_pending from remaining set if we quit.  */
      clear_input_pending ();
      QUIT;
    }

  return got_some_input;
}

/* Read pending output from the process channel,
   starting with our buffered-ahead character if we have one.
   Yield number of characters read.

   This function reads at most 1024 characters.
   If you want to read all available subprocess output,
   you must call it repeatedly until it returns zero.  */

read_process_output (proc, channel)
     Lisp_Object proc;
     register int channel;
{
  register int nchars;
  char chars[1024];
  register Lisp_Object outstream;
  register struct buffer *old = current_buffer;
  register struct Lisp_Process *p = XPROCESS (proc);
  register int opoint;

#ifdef VMS
  VMS_PROC_STUFF *vs, *get_vms_process_pointer();

  vs = get_vms_process_pointer (p);
  nchars = vms_read_fd (channel, chars, sizeof chars, vs->translate_p);
#else /* not VMS */
  if (proc_buffered_char[channel] < 0)
    nchars = read (channel, chars, sizeof chars);
  else
    {
      chars[0] = proc_buffered_char[channel];
      proc_buffered_char[channel] = -1;
      nchars = read (channel, chars + 1, sizeof chars - 1);
      if (nchars < 0)
	nchars = 1;
      else
	nchars = nchars + 1;
    }
#endif /* not VMS */

  if (nchars <= 0) return nchars;

  outstream = p->filter;
  if (!NILP (outstream))
    {
      /* We inhibit quit here instead of just catching it so that 
	 hitting ^G when a filter happens to be running won't screw
	 it up.  */
      int count = specpdl_ptr - specpdl;
      Lisp_Object odeactivate;
      Lisp_Object obuffer;

      odeactivate = Vdeactivate_mark;
      obuffer = Fcurrent_buffer ();

      specbind (Qinhibit_quit, Qt);
      specbind (Qlast_nonmenu_event, Qt);
      call2 (outstream, proc, make_string (chars, nchars));

      /* Handling the process output should not deactivate the mark.  */
      Vdeactivate_mark = odeactivate;

      if (! EQ (Fcurrent_buffer (), obuffer))
	record_asynch_buffer_change ();

      if (waiting_for_user_input_p)
	prepare_menu_bars ();

      unbind_to (count, Qnil);
      return nchars;
    }

  /* If no filter, write into buffer if it isn't dead.  */
  if (!NILP (p->buffer) && !NILP (XBUFFER (p->buffer)->name))
    {
      Lisp_Object old_read_only;
      Lisp_Object old_begv, old_zv;
      Lisp_Object odeactivate;

      odeactivate = Vdeactivate_mark;

      Fset_buffer (p->buffer);
      opoint = point;
      old_read_only = current_buffer->read_only;
      XFASTINT (old_begv) = BEGV;
      XFASTINT (old_zv) = ZV;

      current_buffer->read_only = Qnil;

      /* Insert new output into buffer
	 at the current end-of-output marker,
	 thus preserving logical ordering of input and output.  */
      if (XMARKER (p->mark)->buffer)
	SET_PT (clip_to_bounds (BEGV, marker_position (p->mark), ZV));
      else
	SET_PT (ZV);

      /* If the output marker is outside of the visible region, save
	 the restriction and widen.  */
      if (! (BEGV <= point && point <= ZV))
	Fwiden ();

      /* Make sure opoint floats ahead of any new text, just as point
	 would.  */
      if (point <= opoint)
	opoint += nchars;

      /* Insert after old_begv, but before old_zv.  */
      if (point < XFASTINT (old_begv))
	XFASTINT (old_begv) += nchars;
      if (point <= XFASTINT (old_zv))
	XFASTINT (old_zv) += nchars;

      /* Insert before markers in case we are inserting where
	 the buffer's mark is, and the user's next command is Meta-y.  */
      insert_before_markers (chars, nchars);
      Fset_marker (p->mark, make_number (point), p->buffer);

      update_mode_lines++;

      /* If the restriction isn't what it should be, set it.  */
      if (XFASTINT (old_begv) != BEGV || XFASTINT (old_zv) != ZV)
	Fnarrow_to_region (old_begv, old_zv);

      /* Handling the process output should not deactivate the mark.  */
      Vdeactivate_mark = odeactivate;

      current_buffer->read_only = old_read_only;
      SET_PT (opoint);
      set_buffer_internal (old);
    }
  return nchars;
}

DEFUN ("waiting-for-user-input-p", Fwaiting_for_user_input_p, Swaiting_for_user_input_p,
       0, 0, 0,
  "Returns non-nil if emacs is waiting for input from the user.\n\
This is intended for use by asynchronous process output filters and sentinels.")
       ()
{
  return (waiting_for_user_input_p ? Qt : Qnil);
}

/* Sending data to subprocess */

jmp_buf send_process_frame;

#ifndef VMS
SIGTYPE
send_process_trap ()
{
#ifdef BSD4_1
  sigrelse (SIGPIPE);
  sigrelse (SIGALRM);
#endif /* BSD4_1 */
  longjmp (send_process_frame, 1);
}
#endif /* not VMS */

/* Send some data to process PROC.
   BUF is the beginning of the data; LEN is the number of characters.
   OBJECT is the Lisp object that the data comes from.  */

send_process (proc, buf, len, object)
     Lisp_Object proc;
     char *buf;
     int len;
     Lisp_Object object;
{
  /* Don't use register vars; longjmp can lose them.  */
  int rv;
  unsigned char *procname = XSTRING (XPROCESS (proc)->name)->data;

#ifdef VMS
  struct Lisp_Process *p = XPROCESS (proc);
  VMS_PROC_STUFF *vs, *get_vms_process_pointer();
  vs = get_vms_process_pointer (p);
  if (vs == 0)
    error ("Could not deactivate process: %x",
	   (getpid () & 0xff000000) | p->pid);
#endif /* VMS */

  if (! NILP (XPROCESS (proc)->raw_status_low))
    update_status (XPROCESS (proc));
  if (! EQ (XPROCESS (proc)->status, Qrun))
    error ("Process %s not running", procname);

  if (pty_max_bytes == 0)
    {
#if defined (HAVE_FPATHCONF) && defined (_PC_MAX_CANON)
      pty_max_bytes = fpathconf (XFASTINT (XPROCESS (proc)->outfd),
				 _PC_MAX_CANON);
      if (pty_max_bytes < 0)
	pty_max_bytes = 250;
#else
      pty_max_bytes = 250;
#endif
      /* Deduct one, to leave space for the eof.  */
      pty_max_bytes--;
    }

  if (!setjmp (send_process_frame))
    while (len > 0)
      {
	int this = len;
	SIGTYPE (*old_sigpipe)();
	int flush_pty = 0;

	/* Decide how much data we can send in one batch.
	   Long lines need to be split into multiple batches.  */
	if (!NILP (XPROCESS (proc)->pty_flag))
	  {
	    /* Starting this at zero is always correct when not the first iteration
	       because the previous iteration ended by sending C-d.
	       It may not be correct for the first iteration
	       if a partial line was sent in a separate send_process call.
	       If that proves worth handling, we need to save linepos
	       in the process object.  */
	    int linepos = 0;
	    char *ptr = buf;
	    char *end = buf + len;

	    /* Scan through this text for a line that is too long.  */
	    while (ptr != end && linepos < pty_max_bytes)
	      {
		if (*ptr == '\n')
		  linepos = 0;
		else
		  linepos++;
		ptr++;
	      }
	    /* If we found one, break the line there
	       and put in a C-d to force the buffer through.  */
	    this = ptr - buf;
	  }

	/* Send this batch, using one or more write calls.  */
	while (this > 0)
	  {
#ifdef VMS
#ifdef DEBUG
	fprintf (stderr, "Sending \"%*.*s\"\n", this, this, buf);
#endif /* DEBUG */
	rv = vms_write_fd (XFASTINT (XPROCESS (proc)->outfd), buf, this,
			   vs->translate_p);
#else
	    old_sigpipe = (SIGTYPE (*) ()) signal (SIGPIPE, send_process_trap);
	    rv = write (XINT (XPROCESS (proc)->outfd), buf, this);
	    signal (SIGPIPE, old_sigpipe);
#endif /* VMS */

	    if (rv < 0)
	      {
		if (0
#ifdef EWOULDBLOCK
		    || errno == EWOULDBLOCK
#endif
#ifdef EAGAIN
		    || errno == EAGAIN
#endif
		    )
		  /* Buffer is full.  Wait, accepting input; 
		     that may allow the program
		     to finish doing output and read more.  */
		  {
		    Lisp_Object zero;
		    int offset;

		    /* Running filters might relocate buffers or strings.
		       Arrange to relocate BUF.  */
		    if (BUFFERP (object))
		      offset = BUF_PTR_CHAR_POS (XBUFFER (object),
						 (unsigned char *) buf);
		    else if (STRINGP (object))
		      offset = buf - (char *) XSTRING (object)->data;

		    XFASTINT (zero) = 0;
		    wait_reading_process_input (1, 0, zero, 0);

		    if (BUFFERP (object))
		      buf = (char *) BUF_CHAR_ADDRESS (XBUFFER (object), offset);
		    else if (STRINGP (object))
		      buf = offset + (char *) XSTRING (object)->data;

		    rv = 0;
		  }
		else
		  /* This is a real error.  */
		  report_file_error ("writing to process", Fcons (proc, Qnil));
	      }
	    buf += rv;
	    len -= rv;
	    this -= rv;
	  }

	/* If we sent just part of the string, put in an EOF
	   to force it through, before we send the rest.  */
	if (len > 0)
	  Fprocess_send_eof (proc);
      }
  else
    {
      XPROCESS (proc)->raw_status_low = Qnil;
      XPROCESS (proc)->raw_status_high = Qnil;
      XPROCESS (proc)->status = Fcons (Qexit, Fcons (make_number (256), Qnil));
      XSETINT (XPROCESS (proc)->tick, ++process_tick);
      deactivate_process (proc);
#ifdef VMS
      error ("Error writing to process %s; closed it", procname);
#else
      error ("SIGPIPE raised on process %s; closed it", procname);
#endif
    }
}

DEFUN ("process-send-region", Fprocess_send_region, Sprocess_send_region,
  3, 3, 0,
  "Send current contents of region as input to PROCESS.\n\
PROCESS may be a process, a buffer, the name of a process or buffer, or\n\
nil, indicating the current buffer's process.\n\
Called from program, takes three arguments, PROCESS, START and END.\n\
If the region is more than 500 characters long,\n\
it is sent in several bunches.  This may happen even for shorter regions.\n\
Output from processes can arrive in between bunches.")
  (process, start, end)
     Lisp_Object process, start, end;
{
  Lisp_Object proc;
  int start1;

  proc = get_process (process);
  validate_region (&start, &end);

  if (XINT (start) < GPT && XINT (end) > GPT)
    move_gap (start);

  start1 = XINT (start);
  send_process (proc, &FETCH_CHAR (start1), XINT (end) - XINT (start),
		Fcurrent_buffer ());

  return Qnil;
}

DEFUN ("process-send-string", Fprocess_send_string, Sprocess_send_string,
  2, 2, 0,
  "Send PROCESS the contents of STRING as input.\n\
PROCESS may be a process, a buffer, the name of a process or buffer, or\n\
nil, indicating the current buffer's process.\n\
If STRING is more than 500 characters long,\n\
it is sent in several bunches.  This may happen even for shorter strings.\n\
Output from processes can arrive in between bunches.")
  (process, string)
     Lisp_Object process, string;
{
  Lisp_Object proc;
  CHECK_STRING (string, 1);
  proc = get_process (process);
  send_process (proc, XSTRING (string)->data, XSTRING (string)->size, string);
  return Qnil;
}

/* send a signal number SIGNO to PROCESS.
   CURRENT_GROUP means send to the process group that currently owns
   the terminal being used to communicate with PROCESS.
   This is used for various commands in shell mode.
   If NOMSG is zero, insert signal-announcements into process's buffers
   right away.

   If we can, we try to signal PROCESS by sending control characters
   down the pty.  This allows us to signal inferiors who have changed
   their uid, for which killpg would return an EPERM error.  */

static void
process_send_signal (process, signo, current_group, nomsg)
     Lisp_Object process;
     int signo;
     Lisp_Object current_group;
     int nomsg;
{
  Lisp_Object proc;
  register struct Lisp_Process *p;
  int gid;
  int no_pgrp = 0;
#ifdef VMS
  int status = 1;
#endif

  proc = get_process (process);
  p = XPROCESS (proc);

  if (!EQ (p->childp, Qt))
    error ("Process %s is not a subprocess",
	   XSTRING (p->name)->data);
  if (XINT (p->infd) < 0)
    error ("Process %s is not active",
	   XSTRING (p->name)->data);

  if (NILP (p->pty_flag))
    current_group = Qnil;

  /* If we are using pgrps, get a pgrp number and make it negative.  */
  if (!NILP (current_group))
    {
#ifdef SIGNALS_VIA_CHARACTERS
      /* If possible, send signals to the entire pgrp
	 by sending an input character to it.  */

      /* TERMIOS is the latest and bestest, and seems most likely to
         work.  If the system has it, use it.  */
#ifdef HAVE_TERMIOS
      struct termios t;

      switch (signo)
	{
	case SIGINT:
	  tcgetattr (XINT (p->infd), &t);
	  send_process (proc, &t.c_cc[VINTR], 1, Qnil);
	  return;

	case SIGQUIT:
	  tcgetattr (XINT (p->infd), &t);
  	  send_process (proc, &t.c_cc[VQUIT], 1, Qnil);
  	  return;

  	case SIGTSTP:
	  tcgetattr (XINT (p->infd), &t);
#if defined (VSWTCH) && !defined (PREFER_VSUSP)
  	  send_process (proc, &t.c_cc[VSWTCH], 1, Qnil);
#else
	  send_process (proc, &t.c_cc[VSUSP], 1, Qnil);
#endif
  	  return;
	}

#else /* ! HAVE_TERMIOS */

      /* On Berkeley descendants, the following IOCTL's retrieve the
	 current control characters.  */
#if defined (TIOCGLTC) && defined (TIOCGETC)

      struct tchars c;
      struct ltchars lc;

      switch (signo)
	{
	case SIGINT:
	  ioctl (XINT (p->infd), TIOCGETC, &c);
	  send_process (proc, &c.t_intrc, 1, Qnil);
	  return;
	case SIGQUIT:
	  ioctl (XINT (p->infd), TIOCGETC, &c);
	  send_process (proc, &c.t_quitc, 1, Qnil);
	  return;
#ifdef SIGTSTP
	case SIGTSTP:
	  ioctl (XINT (p->infd), TIOCGLTC, &lc);
	  send_process (proc, &lc.t_suspc, 1, Qnil);
	  return;
#endif /* ! defined (SIGTSTP) */
	}

#else /* ! defined (TIOCGLTC) && defined (TIOCGETC) */

      /* On SYSV descendants, the TCGETA ioctl retrieves the current control
	 characters.  */
#ifdef TCGETA
      struct termio t;
      switch (signo)
	{
	case SIGINT:
	  ioctl (XINT (p->infd), TCGETA, &t);
	  send_process (proc, &t.c_cc[VINTR], 1, Qnil);
	  return;
	case SIGQUIT:
	  ioctl (XINT (p->infd), TCGETA, &t);
	  send_process (proc, &t.c_cc[VQUIT], 1, Qnil);
	  return;
#ifdef SIGTSTP
	case SIGTSTP:
	  ioctl (XINT (p->infd), TCGETA, &t);
	  send_process (proc, &t.c_cc[VSWTCH], 1, Qnil);
	  return;
#endif /* ! defined (SIGTSTP) */
	}
#else /* ! defined (TCGETA) */
      Your configuration files are messed up.
      /* If your system configuration files define SIGNALS_VIA_CHARACTERS,
	 you'd better be using one of the alternatives above!  */
#endif /* ! defined (TCGETA) */
#endif /* ! defined (TIOCGLTC) && defined (TIOCGETC) */
#endif /* ! defined HAVE_TERMIOS */
#endif /* ! defined (SIGNALS_VIA_CHARACTERS) */

#ifdef TIOCGPGRP 
      /* Get the pgrp using the tty itself, if we have that.
	 Otherwise, use the pty to get the pgrp.
	 On pfa systems, saka@pfu.fujitsu.co.JP writes:
	 "TIOCGPGRP symbol defined in sys/ioctl.h at E50.
	 But, TIOCGPGRP does not work on E50 ;-P works fine on E60"
	 His patch indicates that if TIOCGPGRP returns an error, then
	 we should just assume that p->pid is also the process group id.  */
      {
	int err;

	if (!NILP (p->subtty))
	  err = ioctl (XFASTINT (p->subtty), TIOCGPGRP, &gid);
	else
	  err = ioctl (XINT (p->infd), TIOCGPGRP, &gid);

#ifdef pfa
	if (err == -1)
	  gid = - XFASTINT (p->pid);
#endif /* ! defined (pfa) */
      }
      if (gid == -1)
	no_pgrp = 1;
      else
	gid = - gid;
#else  /* ! defined (TIOCGPGRP ) */
      /* Can't select pgrps on this system, so we know that
	 the child itself heads the pgrp.  */
      gid = - XFASTINT (p->pid);
#endif /* ! defined (TIOCGPGRP ) */
    }
  else
    gid = - XFASTINT (p->pid);

#ifdef VMS
  gid = - ((getpid () & 0xff000000) | (XFASTINT (p->pid)));
#endif

  switch (signo)
    {
#ifdef SIGCONT
    case SIGCONT:
      p->raw_status_low = Qnil;
      p->raw_status_high = Qnil;
      p->status = Qrun;
      XSETINT (p->tick, ++process_tick);
      if (!nomsg)
	status_notify ();
      break;
#endif /* ! defined (SIGCONT) */
    case SIGINT:
#ifdef VMS
      send_process (proc, "\003", 1, Qnil);	/* ^C */
      goto whoosh;
#endif
    case SIGQUIT:
#ifdef VMS
      {
	unsigned long tem_pid = (getpid () & 0xff000000) | (XFASTINT (p->pid));
	status = sys$forcex (&tem_pid, 0, SS$_FORCEDEXIT);
	goto whoosh;
      }
#endif
    case SIGKILL:
#ifdef VMS
      {
	unsigned long tem_pid = (getpid () & 0xff000000) | (XFASTINT (p->pid));
	int status = sys$delprc (&tem_pid, 0);
      }
      whoosh:
#endif
      flush_pending_output (XINT (p->infd));
      break;
    }

  /* If we don't have process groups, send the signal to the immediate
     subprocess.  That isn't really right, but it's better than any
     obvious alternative.  */
  if (no_pgrp)
    {
      kill (XFASTINT (p->pid), signo);
      return;
    }

  /* gid may be a pid, or minus a pgrp's number */
#ifdef TIOCSIGSEND
  if (!NILP (current_group))
    ioctl (XINT (p->infd), TIOCSIGSEND, signo);
  else
    {
      gid = - XFASTINT (p->pid);
      kill (gid, signo);
    }
#else /* ! defined (TIOCSIGSEND) */
  EMACS_KILLPG (-gid, signo);
#endif /* ! defined (TIOCSIGSEND) */
#ifdef VMS
  if ((status & 1) != 1)
    {
      vaxc$errno = status;
      error ("process_send_signal error: %s", err_str (EVMSERR));
    }
#endif
}

DEFUN ("interrupt-process", Finterrupt_process, Sinterrupt_process, 0, 2, 0,
  "Interrupt process PROCESS.  May be process or name of one.\n\
PROCESS may be a process, a buffer, or the name of a process or buffer.\n\
nil or no arg means current buffer's process.\n\
Second arg CURRENT-GROUP non-nil means send signal to\n\
the current process-group of the process's controlling terminal\n\
rather than to the process's own process group.\n\
If the process is a shell, this means interrupt current subjob\n\
rather than the shell.")
  (process, current_group)
     Lisp_Object process, current_group;
{
  process_send_signal (process, SIGINT, current_group, 0);
  return process;
}

DEFUN ("kill-process", Fkill_process, Skill_process, 0, 2, 0,
  "Kill process PROCESS.  May be process or name of one.\n\
See function `interrupt-process' for more details on usage.")
  (process, current_group)
     Lisp_Object process, current_group;
{
  process_send_signal (process, SIGKILL, current_group, 0);
  return process;
}

DEFUN ("quit-process", Fquit_process, Squit_process, 0, 2, 0,
  "Send QUIT signal to process PROCESS.  May be process or name of one.\n\
See function `interrupt-process' for more details on usage.")
  (process, current_group)
     Lisp_Object process, current_group;
{
  process_send_signal (process, SIGQUIT, current_group, 0);
  return process;
}

DEFUN ("stop-process", Fstop_process, Sstop_process, 0, 2, 0,
  "Stop process PROCESS.  May be process or name of one.\n\
See function `interrupt-process' for more details on usage.")
  (process, current_group)
     Lisp_Object process, current_group;
{
#ifndef SIGTSTP
  error ("no SIGTSTP support");
#else
  process_send_signal (process, SIGTSTP, current_group, 0);
#endif
  return process;
}

DEFUN ("continue-process", Fcontinue_process, Scontinue_process, 0, 2, 0,
  "Continue process PROCESS.  May be process or name of one.\n\
See function `interrupt-process' for more details on usage.")
  (process, current_group)
     Lisp_Object process, current_group;
{
#ifdef SIGCONT
    process_send_signal (process, SIGCONT, current_group, 0);
#else
    error ("no SIGCONT support");
#endif
  return process;
}

DEFUN ("signal-process", Fsignal_process, Ssignal_process,
  2, 2, "nProcess number: \nnSignal code: ",
  "Send the process with number PID the signal with code CODE.\n\
Both PID and CODE are integers.")
  (pid, sig)
     Lisp_Object pid, sig;
{
  CHECK_NUMBER (pid, 0);
  CHECK_NUMBER (sig, 1);
  return make_number (kill (XINT (pid), XINT (sig)));
}

DEFUN ("process-send-eof", Fprocess_send_eof, Sprocess_send_eof, 0, 1, 0,
  "Make PROCESS see end-of-file in its input.\n\
Eof comes after any text already sent to it.\n\
PROCESS may be a process, a buffer, the name of a process or buffer, or\n\
nil, indicating the current buffer's process.\n\
If PROCESS is a network connection, or is a process communicating\n\
through a pipe (as opposed to a pty), then you cannot send any more\n\
text to PROCESS after you call this function.")
  (process)
     Lisp_Object process;
{
  Lisp_Object proc;

  proc = get_process (process);

  /* Make sure the process is really alive.  */
  if (! NILP (XPROCESS (proc)->raw_status_low))
    update_status (XPROCESS (proc));
  if (! EQ (XPROCESS (proc)->status, Qrun))
    error ("Process %s not running", XSTRING (XPROCESS (proc)->name)->data);

  /* Sending a zero-length record is supposed to mean eof
     when TIOCREMOTE is turned on.  */
#ifdef DID_REMOTE
  {
    char buf[1];
    write (XINT (XPROCESS (proc)->outfd), buf, 0);
  }
#else /* did not do TOICREMOTE */
#ifdef VMS
  send_process (proc, "\032", 1, Qnil); 	/* ^z */
#else
  if (!NILP (XPROCESS (proc)->pty_flag))
    send_process (proc, "\004", 1, Qnil);
  else
    {
      close (XINT (XPROCESS (proc)->outfd));
      XSET (XPROCESS (proc)->outfd, Lisp_Int, open (NULL_DEVICE, O_WRONLY));
    }
#endif /* VMS */
#endif /* did not do TOICREMOTE */
  return process;
}

/* Kill all processes associated with `buffer'.
 If `buffer' is nil, kill all processes  */

kill_buffer_processes (buffer)
     Lisp_Object buffer;
{
  Lisp_Object tail, proc;

  for (tail = Vprocess_alist; XGCTYPE (tail) == Lisp_Cons;
       tail = XCONS (tail)->cdr)
    {
      proc = XCONS (XCONS (tail)->car)->cdr;
      if (XGCTYPE (proc) == Lisp_Process
	  && (NILP (buffer) || EQ (XPROCESS (proc)->buffer, buffer)))
	{
	  if (NETCONN_P (proc))
	    Fdelete_process (proc);
	  else if (XINT (XPROCESS (proc)->infd) >= 0)
	    process_send_signal (proc, SIGHUP, Qnil, 1);
	}
    }
}

/* On receipt of a signal that a child status has changed,
 loop asking about children with changed statuses until
 the system says there are no more.
   All we do is change the status;
 we do not run sentinels or print notifications.
 That is saved for the next time keyboard input is done,
 in order to avoid timing errors.  */

/** WARNING: this can be called during garbage collection.
 Therefore, it must not be fooled by the presence of mark bits in
 Lisp objects.  */

/** USG WARNING:  Although it is not obvious from the documentation
 in signal(2), on a USG system the SIGCLD handler MUST NOT call
 signal() before executing at least one wait(), otherwise the handler
 will be called again, resulting in an infinite loop.  The relevant
 portion of the documentation reads "SIGCLD signals will be queued
 and the signal-catching function will be continually reentered until
 the queue is empty".  Invoking signal() causes the kernel to reexamine
 the SIGCLD queue.   Fred Fish, UniSoft Systems Inc. */

SIGTYPE
sigchld_handler (signo)
     int signo;
{
  int old_errno = errno;
  Lisp_Object proc;
  register struct Lisp_Process *p;
  extern EMACS_TIME *input_available_clear_time;

#ifdef BSD4_1
  extern int sigheld;
  sigheld |= sigbit (SIGCHLD);
#endif

  while (1)
    {
      register int pid;
      WAITTYPE w;
      Lisp_Object tail;

#ifdef WNOHANG
#ifndef WUNTRACED
#define WUNTRACED 0
#endif /* no WUNTRACED */
      /* Keep trying to get a status until we get a definitive result.  */
      do 
	{
	  errno = 0;
	  pid = wait3 (&w, WNOHANG | WUNTRACED, 0);
	}
      while (pid <= 0 && errno == EINTR);

      if (pid <= 0)
	{
	  /* A real failure.  We have done all our job, so return.  */

	  /* USG systems forget handlers when they are used;
	     must reestablish each time */
#ifdef USG
	  signal (signo, sigchld_handler);   /* WARNING - must come after wait3() */
#endif
#ifdef  BSD4_1
	  sigheld &= ~sigbit (SIGCHLD);
	  sigrelse (SIGCHLD);
#endif
	  errno = old_errno;
	  return;
	}
#else
      pid = wait (&w);
#endif /* no WNOHANG */

      /* Find the process that signaled us, and record its status.  */

      p = 0;
      for (tail = Vprocess_alist; XSYMBOL (tail) != XSYMBOL (Qnil); tail = XCONS (tail)->cdr)
	{
	  proc = XCONS (XCONS (tail)->car)->cdr;
	  p = XPROCESS (proc);
	  if (EQ (p->childp, Qt) && XFASTINT (p->pid) == pid)
	    break;
	  p = 0;
	}

      /* Look for an asynchronous process whose pid hasn't been filled
	 in yet.  */
      if (p == 0)
	for (tail = Vprocess_alist; XSYMBOL (tail) != XSYMBOL (Qnil); tail = XCONS (tail)->cdr)
	  {
	    proc = XCONS (XCONS (tail)->car)->cdr;
	    p = XPROCESS (proc);
	    if (XTYPE (p->pid) == Lisp_Int && XINT (p->pid) == -1)
	      break;
	    p = 0;
	  }
      
      /* Change the status of the process that was found.  */
      if (p != 0)
	{
	  union { int i; WAITTYPE wt; } u;
	  
	  XSETINT (p->tick, ++process_tick);
	  u.wt = w;
	  XFASTINT (p->raw_status_low) = u.i & 0xffff;
	  XFASTINT (p->raw_status_high) = u.i >> 16;
	  
	  /* If process has terminated, stop waiting for its output.  */
	  if (WIFSIGNALED (w) || WIFEXITED (w))
	    if (XINT (p->infd) >= 0)
	      FD_CLR (XINT (p->infd), &input_wait_mask);

	  /* Tell wait_reading_process_input that it needs to wake up and
	     look around.  */
	  if (input_available_clear_time)
	    EMACS_SET_SECS_USECS (*input_available_clear_time, 0, 0);
	}

	/* There was no asynchronous process found for that id.  Check
	   if we have a synchronous process.  */
      else
	{
	  synch_process_alive = 0;

	  /* Report the status of the synchronous process.  */
	  if (WIFEXITED (w))
	    synch_process_retcode = WRETCODE (w);
	  else if (WIFSIGNALED (w))
	    {
	      int code = WTERMSIG (w);
	      char *signame = 0;

	      if (code < NSIG)
		  signame = sys_siglist[code];
	      if (signame == 0)
		signame = "unknown";

	      synch_process_death = signame;
	    }

	  /* Tell wait_reading_process_input that it needs to wake up and
	     look around.  */
	  if (input_available_clear_time)
	    EMACS_SET_SECS_USECS (*input_available_clear_time, 0, 0);
	}

      /* On some systems, we must return right away.
	 If any more processes want to signal us, we will
	 get another signal.
	 Otherwise (on systems that have WNOHANG), loop around
	 to use up all the processes that have something to tell us.  */
#if defined (USG) && ! (defined (HPUX) && defined (WNOHANG))
#ifdef USG
      signal (signo, sigchld_handler);
#endif
      errno = old_errno;
      return;
#endif /* USG, but not HPUX with WNOHANG */
    }
}


static Lisp_Object
exec_sentinel_unwind (data)
     Lisp_Object data;
{
  XPROCESS (XCONS (data)->car)->sentinel = XCONS (data)->cdr;
  return Qnil;
}

static void
exec_sentinel (proc, reason)
     Lisp_Object proc, reason;
{
  Lisp_Object sentinel, obuffer, odeactivate;
  register struct Lisp_Process *p = XPROCESS (proc);
  int count = specpdl_ptr - specpdl;

  odeactivate = Vdeactivate_mark;
  obuffer = Fcurrent_buffer ();
  sentinel = p->sentinel;
  if (NILP (sentinel))
    return;

  /* Zilch the sentinel while it's running, to avoid recursive invocations;
     assure that it gets restored no matter how the sentinel exits.  */
  p->sentinel = Qnil;
  record_unwind_protect (exec_sentinel_unwind, Fcons (proc, sentinel));
  /* Inhibit quit so that random quits don't screw up a running filter.  */
  specbind (Qinhibit_quit, Qt);
  specbind (Qlast_nonmenu_event, Qt);
  call2 (sentinel, proc, reason);

  Vdeactivate_mark = odeactivate;
  if (! EQ (Fcurrent_buffer (), obuffer))
    record_asynch_buffer_change ();

  if (waiting_for_user_input_p)
    prepare_menu_bars ();
  unbind_to (count, Qnil);
}

/* Report all recent events of a change in process status
   (either run the sentinel or output a message).
   This is done while Emacs is waiting for keyboard input.  */

status_notify ()
{
  register Lisp_Object proc, buffer;
  Lisp_Object tail, msg;
  struct gcpro gcpro1, gcpro2;

  tail = Qnil;
  msg = Qnil;
  /* We need to gcpro tail; if read_process_output calls a filter
     which deletes a process and removes the cons to which tail points
     from Vprocess_alist, and then causes a GC, tail is an unprotected
     reference.  */
  GCPRO2 (tail, msg);

  for (tail = Vprocess_alist; !NILP (tail); tail = Fcdr (tail))
    {
      Lisp_Object symbol;
      register struct Lisp_Process *p;

      proc = Fcdr (Fcar (tail));
      p = XPROCESS (proc);

      if (XINT (p->tick) != XINT (p->update_tick))
	{
	  XSETINT (p->update_tick, XINT (p->tick));

	  /* If process is still active, read any output that remains.  */
	  if (XINT (p->infd) >= 0)
	    while (! EQ (p->filter, Qt)
		   && read_process_output (proc, XINT (p->infd)) > 0);

	  buffer = p->buffer;

	  /* Get the text to use for the message.  */
	  if (!NILP (p->raw_status_low))
	    update_status (p);
	  msg = status_message (p->status);

	  /* If process is terminated, deactivate it or delete it.  */
	  symbol = p->status;
	  if (XTYPE (p->status) == Lisp_Cons)
	    symbol = XCONS (p->status)->car;

	  if (EQ (symbol, Qsignal) || EQ (symbol, Qexit)
	      || EQ (symbol, Qclosed))
	    {
	      if (delete_exited_processes)
		remove_process (proc);
	      else
		deactivate_process (proc);
	    }

	  /* Now output the message suitably.  */
	  if (!NILP (p->sentinel))
	    exec_sentinel (proc, msg);
	  /* Don't bother with a message in the buffer
	     when a process becomes runnable.  */
	  else if (!EQ (symbol, Qrun) && !NILP (buffer))
	    {
	      Lisp_Object ro, tem;
	      struct buffer *old = current_buffer;
	      int opoint;

	      ro = XBUFFER (buffer)->read_only;

	      /* Avoid error if buffer is deleted
		 (probably that's why the process is dead, too) */
	      if (NILP (XBUFFER (buffer)->name))
		continue;
	      Fset_buffer (buffer);
	      opoint = point;
	      /* Insert new output into buffer
		 at the current end-of-output marker,
		 thus preserving logical ordering of input and output.  */
	      if (XMARKER (p->mark)->buffer)
		SET_PT (marker_position (p->mark));
	      else
		SET_PT (ZV);
	      if (point <= opoint)
		opoint += XSTRING (msg)->size + XSTRING (p->name)->size + 10;

	      tem = current_buffer->read_only;
	      current_buffer->read_only = Qnil;
	      insert_string ("\nProcess ");
	      Finsert (1, &p->name);
	      insert_string (" ");
	      Finsert (1, &msg);
	      current_buffer->read_only = tem;
	      Fset_marker (p->mark, make_number (point), p->buffer);

	      SET_PT (opoint);
	      set_buffer_internal (old);
	    }
	}
    } /* end for */

  update_mode_lines++;  /* in case buffers use %s in mode-line-format */
  redisplay_preserve_echo_area ();

  update_tick = process_tick;

  UNGCPRO;
}

init_process ()
{
  register int i;

#ifdef SIGCHLD
#ifndef CANNOT_DUMP
  if (! noninteractive || initialized)
#endif
    signal (SIGCHLD, sigchld_handler);
#endif

  FD_ZERO (&input_wait_mask);
  max_process_desc = 0;

  keyboard_descriptor = 0;
  FD_SET (keyboard_descriptor, &input_wait_mask);

  Vprocess_alist = Qnil;
  for (i = 0; i < MAXDESC; i++)
    {
      chan_process[i] = Qnil;
      proc_buffered_char[i] = -1;
    }
}

/* From now on, assume keyboard input comes from descriptor DESC.  */

void
change_keyboard_wait_descriptor (desc)
     int desc;
{
#ifdef VMS
  /* On VMS, desc will contain a channel number.  */
  extern VMS_CHAN_STUFF *get_vms_channel_pointer ();
  VMS_CHAN_STUFF * vs = get_vms_channel_pointer (0);
  vs->chan = desc;
  desc = get_vms_channel_handle (vs);
#endif
  FD_CLR (keyboard_descriptor, &input_wait_mask);
  keyboard_descriptor = desc;
  FD_SET (keyboard_descriptor, &input_wait_mask);
}

syms_of_process ()
{
#ifdef HAVE_SOCKETS
  stream_process = intern ("stream");
#endif
  Qprocessp = intern ("processp");
  staticpro (&Qprocessp);
  Qrun = intern ("run");
  staticpro (&Qrun);
  Qstop = intern ("stop");
  staticpro (&Qstop);
  Qsignal = intern ("signal");
  staticpro (&Qsignal);

  /* Qexit is already staticpro'd by syms_of_eval; don't staticpro it
     here again.

     Qexit = intern ("exit");
     staticpro (&Qexit); */

  Qopen = intern ("open");
  staticpro (&Qopen);
  Qclosed = intern ("closed");
  staticpro (&Qclosed);

  Qlast_nonmenu_event = intern ("last-nonmenu-event");
  staticpro (&Qlast_nonmenu_event);

  staticpro (&Vprocess_alist);

  DEFVAR_BOOL ("delete-exited-processes", &delete_exited_processes,
    "*Non-nil means delete processes immediately when they exit.\n\
nil means don't delete them until `list-processes' is run.");

  delete_exited_processes = 1;

  DEFVAR_LISP ("process-connection-type", &Vprocess_connection_type,
    "Control type of device used to communicate with subprocesses.\n\
Values are nil to use a pipe, or t or `pty' to use a pty.\n\
The value has no effect if the system has no ptys or if all ptys are busy:\n\
then a pipe is used in any case.\n\
The value takes effect when `start-process' is called.");
  Vprocess_connection_type = Qt;

  DEFVAR_BOOL ("vms-split-status-code", &vms_split_status_code,
    "Non-nil means split the status code returned by subprocesses.\n\
nil means return the status code as is.  This variable is meaningful\n\
only on VMS.\n\
On VMS, the status code is really a 32-bit array of bit fields, with\n\
the folowing meaning:\n\
\n\
  SEVERITY:  Bits 0-2 contain the severity level of the message.\n\
  MESSAGE:   Bits 3-15 contain the number of the corresponding\n\
             message.\n\
  FACILITY:  Bits 16-27 contain a number for the software component,\n\
             or facility, that generated the message.\n\
  INTERNAL:  Bits 28-31 contain internal control flags.\n\
\n\
Normally, it is just returned as one integer, but when\n\
vms-split-status-code is t, the status code will instead be returned as\n\
(SEVERITY MESSAGE FACILITY INTERNAL).");
  vms_split_status_code = 0;

  defsubr (&Sprocessp);
  defsubr (&Sget_process);
  defsubr (&Sget_buffer_process);
  defsubr (&Sdelete_process);
  defsubr (&Sprocess_status);
  defsubr (&Sprocess_exit_status);
  defsubr (&Sprocess_id);
  defsubr (&Sprocess_name);
  defsubr (&Sprocess_command);
  defsubr (&Sset_process_buffer);
  defsubr (&Sprocess_buffer);
  defsubr (&Sprocess_mark);
  defsubr (&Sset_process_filter);
  defsubr (&Sprocess_filter);
  defsubr (&Sset_process_sentinel);
  defsubr (&Sset_process_window_size);
  defsubr (&Sprocess_sentinel);
  defsubr (&Sprocess_kill_without_query);
  defsubr (&Slist_processes);
  defsubr (&Sprocess_list);
  defsubr (&Sstart_process);
#ifdef HAVE_SOCKETS
  defsubr (&Sopen_network_stream);
#endif /* HAVE_SOCKETS */
  defsubr (&Saccept_process_output);
  defsubr (&Sprocess_send_region);
  defsubr (&Sprocess_send_string);
  defsubr (&Sinterrupt_process);
  defsubr (&Skill_process);
  defsubr (&Squit_process);
  defsubr (&Sstop_process);
  defsubr (&Scontinue_process);
  defsubr (&Sprocess_send_eof);
  defsubr (&Ssignal_process);
  defsubr (&Swaiting_for_user_input_p);
/*  defsubr (&Sprocess_connection); */
}


#else /* not subprocesses */

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

#include "lisp.h"
#include "systime.h"
#include "termopts.h"

extern int frame_garbaged;


/* As described above, except assuming that there are no subprocesses:

   Wait for timeout to elapse and/or keyboard input to be available.

   time_limit is:
     timeout in seconds, or
     zero for no limit, or
     -1 means gobble data immediately available but don't wait for any.

   read_kbd is a Lisp_Object:
     0 to ignore keyboard input, or
     1 to return when input is available, or
     -1 means caller will actually read the input, so don't throw to
       the quit handler.
     We know that read_kbd will never be a Lisp_Process, since
     `subprocesses' isn't defined.

   do_display != 0 means redisplay should be done to show subprocess
   output that arrives.

   Return true iff we received input from any process.  */

int
wait_reading_process_input (time_limit, microsecs, read_kbd, do_display)
     int time_limit, microsecs;
     Lisp_Object read_kbd;
     int do_display;
{
  EMACS_TIME end_time, timeout, *timeout_p;
  int waitchannels;

  /* What does time_limit really mean?  */
  if (time_limit || microsecs)
    {
      /* It's not infinite.  */
      timeout_p = &timeout;

      if (time_limit == -1)
	/* In fact, it's zero.  */
	EMACS_SET_SECS_USECS (timeout, 0, 0);
      else
	EMACS_SET_SECS_USECS (timeout, time_limit, microsecs);

      /* How far in the future is that?  */
      EMACS_GET_TIME (end_time);
      EMACS_ADD_TIME (end_time, end_time, timeout);
    }
  else
    /* It's infinite.  */
    timeout_p = 0;

  /* This must come before stop_polling.  */
  prepare_menu_bars ();

  /* Turn off periodic alarms (in case they are in use)
     because the select emulator uses alarms.  */
  stop_polling ();

  for (;;)
    {
      int nfds;

      waitchannels = XINT (read_kbd) ? 1 : 0;

      /* If calling from keyboard input, do not quit
	 since we want to return C-g as an input character.
	 Otherwise, do pending quit if requested.  */
      if (XINT (read_kbd) >= 0)
	QUIT;

      if (timeout_p)
	{
	  EMACS_GET_TIME (*timeout_p);
	  EMACS_SUB_TIME (*timeout_p, end_time, *timeout_p);
	  if (EMACS_TIME_NEG_P (*timeout_p))
	    break;
	}

      /* Cause C-g and alarm signals to take immediate action,
	 and cause input available signals to zero out timeout.  */
      if (XINT (read_kbd) < 0)
	set_waiting_for_input (&timeout);

      /* If a frame has been newly mapped and needs updating,
	 reprocess its display stuff.  */
      if (frame_garbaged && do_display)
	redisplay_preserve_echo_area ();

      if (XINT (read_kbd) && detect_input_pending ())
	nfds = 0;
      else
	nfds = select (1, &waitchannels, 0, 0, timeout_p);

      /* Make C-g and alarm signals set flags again */
      clear_waiting_for_input ();

      /*  If we woke up due to SIGWINCH, actually change size now.  */
      do_pending_window_change ();

      if (nfds == -1)
	{
	  /* If the system call was interrupted, then go around the
	     loop again.  */
	  if (errno == EINTR)
	    waitchannels = 0;
	}
#ifdef sun
      else if (nfds > 0 && (waitchannels & 1)  && interrupt_input)
	/* System sometimes fails to deliver SIGIO.  */
	kill (getpid (), SIGIO);
#endif
#ifdef SIGIO
      if (XINT (read_kbd) && interrupt_input && (waitchannels & 1))
	kill (0, SIGIO);
#endif

      /* If we have timed out (nfds == 0) or found some input (nfds > 0),
	 we should exit.  */
      if (nfds >= 0)
	break;
    }

  start_polling ();

  return 0;
}


DEFUN ("get-buffer-process", Fget_buffer_process, Sget_buffer_process, 1, 1, 0,
  /* Don't confuse make-docfile by having two doc strings for this function.
     make-docfile does not pay attention to #if, for good reason!  */
  0)
  (name)
     register Lisp_Object name;
{
  return Qnil;
}

/* Kill all processes associated with `buffer'.
   If `buffer' is nil, kill all processes.
   Since we have no subprocesses, this does nothing.  */

kill_buffer_processes (buffer)
     Lisp_Object buffer;
{
}

init_process ()
{
}

syms_of_process ()
{
  defsubr (&Sget_buffer_process);
}


#endif /* not subprocesses */
