process.c

/* Asynchronous subprocess control for GNU Emacs.
   Copyright (C) 1985, 1986, 1987, 1988, 1993, 1994, 1995,
		 1996, 1998, 1999, 2001, 2002, 2003, 2004,
		 2005, 2006, 2007, 2008, 2009, 2010 Free Software Foundation, Inc.

This file is part of GNU Emacs.

GNU Emacs is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

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

You should have received a copy of the GNU General Public License
along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */


#include <config.h>
#include <signal.h>
#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>
#include <setjmp.h>
#ifdef HAVE_INTTYPES_H
#include <inttypes.h>
#endif
#ifdef STDC_HEADERS
#include <stdlib.h>
#endif

#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#include <fcntl.h>

/* Only MS-DOS does not define `subprocesses'.  */
#ifdef subprocesses

#include <sys/socket.h>
#include <netdb.h>
#include <netinet/in.h>
#include <arpa/inet.h>

/* Are local (unix) sockets supported?  */
#if defined (HAVE_SYS_UN_H)
#if !defined (AF_LOCAL) && defined (AF_UNIX)
#define AF_LOCAL AF_UNIX
#endif
#ifdef AF_LOCAL
#define HAVE_LOCAL_SOCKETS
#include <sys/un.h>
#endif
#endif

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

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

/* Can we use SIOCGIFCONF and/or SIOCGIFADDR */
#if defined(HAVE_SYS_IOCTL_H) && defined(HAVE_NET_IF_H)
/* sys/ioctl.h may have been included already */
#ifndef SIOCGIFADDR
#include <sys/ioctl.h>
#endif
#include <net/if.h>
#endif

#ifdef HAVE_SYS_WAIT
#include <sys/wait.h>
#endif

#ifdef HAVE_RES_INIT
#include <netinet/in.h>
#include <arpa/nameser.h>
#include <resolv.h>
#endif

#ifdef HAVE_UTIL_H
#include <util.h>
#endif

#endif	/* subprocesses */

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

#include "window.h"
#include "buffer.h"
#include "character.h"
#include "coding.h"
#include "process.h"
#include "frame.h"
#include "termhooks.h"
#include "termopts.h"
#include "commands.h"
#include "keyboard.h"
#include "blockinput.h"
#include "dispextern.h"
#include "composite.h"
#include "atimer.h"
#include "sysselect.h"
#include "syssignal.h"
#include "syswait.h"

#if defined (USE_GTK) || defined (HAVE_GCONF)
#include "xgselect.h"
#endif /* defined (USE_GTK) || defined (HAVE_GCONF) */
#ifdef HAVE_NS
#include "nsterm.h"
#endif
extern int timers_run;

Lisp_Object Qeuid, Qegid, Qcomm, Qstate, Qppid, Qpgrp, Qsess, Qttname, Qtpgid;
Lisp_Object Qminflt, Qmajflt, Qcminflt, Qcmajflt, Qutime, Qstime, Qcstime;
Lisp_Object Qcutime, Qpri, Qnice, Qthcount, Qstart, Qvsize, Qrss, Qargs;
Lisp_Object Quser, Qgroup, Qetime, Qpcpu, Qpmem, Qtime, Qctime;
Lisp_Object QCname, QCtype;

/* Non-zero if keyboard input is on hold, zero otherwise.  */

static int kbd_is_on_hold;

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

/* Nonzero means don't run process sentinels.  This is used
   when exiting.  */
int inhibit_sentinels;

#ifdef subprocesses

Lisp_Object Qprocessp;
Lisp_Object Qrun, Qstop, Qsignal;
Lisp_Object Qopen, Qclosed, Qconnect, Qfailed, Qlisten;
Lisp_Object Qlocal, Qipv4, Qdatagram, Qseqpacket;
Lisp_Object Qreal, Qnetwork, Qserial;
#ifdef AF_INET6
Lisp_Object Qipv6;
#endif
Lisp_Object QCport, QCspeed, QCprocess;
Lisp_Object QCbytesize, QCstopbits, QCparity, Qodd, Qeven;
Lisp_Object QCflowcontrol, Qhw, Qsw, QCsummary;
Lisp_Object QCbuffer, QChost, QCservice;
Lisp_Object QClocal, QCremote, QCcoding;
Lisp_Object QCserver, QCnowait, QCnoquery, QCstop;
Lisp_Object QCsentinel, QClog, QCoptions, QCplist;
Lisp_Object Qlast_nonmenu_event;
/* QCfamily is declared and initialized in xfaces.c,
   QCfilter in keyboard.c.  */
extern Lisp_Object QCfamily, QCfilter;

/* Qexit is declared and initialized in eval.c.  */

/* QCfamily is defined in xfaces.c.  */
extern Lisp_Object QCfamily;
/* QCfilter is defined in keyboard.c.  */
extern Lisp_Object QCfilter;

#define NETCONN_P(p) (EQ (XPROCESS (p)->type, Qnetwork))
#define NETCONN1_P(p) (EQ ((p)->type, Qnetwork))
#define SERIALCONN_P(p) (EQ (XPROCESS (p)->type, Qserial))
#define SERIALCONN1_P(p) (EQ ((p)->type, Qserial))

/* Define first descriptor number available for subprocesses.  */
#define FIRST_PROC_DESC 3

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

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

extern char *get_operating_system_release (void);

/* Serial processes require termios or Windows.  */
#if defined (HAVE_TERMIOS) || defined (WINDOWSNT)
#define HAVE_SERIAL
#endif

#ifdef HAVE_SERIAL
/* From sysdep.c or w32.c  */
extern int serial_open (char *port);
extern void serial_configure (struct Lisp_Process *p, Lisp_Object contact);
#endif

#ifndef HAVE_H_ERRNO
extern int h_errno;
#endif

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

/* These next two vars are non-static since sysdep.c uses them in the
   emulation of `select'.  */
/* Number of events of change of status of a process.  */
int process_tick;
/* Number of events for which the user or sentinel has been notified.  */
int update_tick;

/* Define NON_BLOCKING_CONNECT if we can support non-blocking connects.  */

#ifdef BROKEN_NON_BLOCKING_CONNECT
#undef NON_BLOCKING_CONNECT
#else
#ifndef NON_BLOCKING_CONNECT
#ifdef HAVE_SELECT
#if defined (HAVE_GETPEERNAME) || defined (GNU_LINUX)
#if defined (O_NONBLOCK) || defined (O_NDELAY)
#if defined (EWOULDBLOCK) || defined (EINPROGRESS)
#define NON_BLOCKING_CONNECT
#endif /* EWOULDBLOCK || EINPROGRESS */
#endif /* O_NONBLOCK || O_NDELAY */
#endif /* HAVE_GETPEERNAME || GNU_LINUX */
#endif /* HAVE_SELECT */
#endif /* NON_BLOCKING_CONNECT */
#endif /* BROKEN_NON_BLOCKING_CONNECT */

/* Define DATAGRAM_SOCKETS if datagrams can be used safely on
   this system.  We need to read full packets, so we need a
   "non-destructive" select.  So we require either native select,
   or emulation of select using FIONREAD.  */

#ifdef BROKEN_DATAGRAM_SOCKETS
#undef DATAGRAM_SOCKETS
#else
#ifndef DATAGRAM_SOCKETS
#if defined (HAVE_SELECT) || defined (FIONREAD)
#if defined (HAVE_SENDTO) && defined (HAVE_RECVFROM) && defined (EMSGSIZE)
#define DATAGRAM_SOCKETS
#endif /* HAVE_SENDTO && HAVE_RECVFROM && EMSGSIZE */
#endif /* HAVE_SELECT || FIONREAD */
#endif /* DATAGRAM_SOCKETS */
#endif /* BROKEN_DATAGRAM_SOCKETS */

#if defined HAVE_LOCAL_SOCKETS && defined DATAGRAM_SOCKETS
# define HAVE_SEQPACKET
#endif

#if !defined (ADAPTIVE_READ_BUFFERING) && !defined (NO_ADAPTIVE_READ_BUFFERING)
#ifdef EMACS_HAS_USECS
#define ADAPTIVE_READ_BUFFERING
#endif
#endif

#ifdef ADAPTIVE_READ_BUFFERING
#define READ_OUTPUT_DELAY_INCREMENT 10000
#define READ_OUTPUT_DELAY_MAX       (READ_OUTPUT_DELAY_INCREMENT * 5)
#define READ_OUTPUT_DELAY_MAX_MAX   (READ_OUTPUT_DELAY_INCREMENT * 7)

/* Number of processes which have a non-zero read_output_delay,
   and therefore might be delayed for adaptive read buffering.  */

static int process_output_delay_count;

/* Non-zero if any process has non-nil read_output_skip.  */

static int process_output_skip;

/* Non-nil means to delay reading process output to improve buffering.
   A value of t means that delay is reset after each send, any other
   non-nil value does not reset the delay.  A value of nil disables
   adaptive read buffering completely.  */
static Lisp_Object Vprocess_adaptive_read_buffering;
#else
#define process_output_delay_count 0
#endif

static int keyboard_bit_set (SELECT_TYPE *);
static void deactivate_process (Lisp_Object);
static void status_notify (struct Lisp_Process *);
static int read_process_output (Lisp_Object, int);
static void create_pty (Lisp_Object);

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

static Lisp_Object get_process (register Lisp_Object name);
static void exec_sentinel (Lisp_Object proc, Lisp_Object reason);

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

static SELECT_TYPE input_wait_mask;

/* Mask that excludes keyboard input descriptor(s).  */

static SELECT_TYPE non_keyboard_wait_mask;

/* Mask that excludes process input descriptor(s).  */

static SELECT_TYPE non_process_wait_mask;

/* Mask for the gpm mouse input descriptor.  */

static SELECT_TYPE gpm_wait_mask;

#ifdef NON_BLOCKING_CONNECT
/* Mask of bits indicating the descriptors that we wait for connect to
   complete on.  Once they complete, they are removed from this mask
   and added to the input_wait_mask and non_keyboard_wait_mask.  */

static SELECT_TYPE connect_wait_mask;

/* Number of bits set in connect_wait_mask.  */
static int num_pending_connects;

#define IF_NON_BLOCKING_CONNECT(s) s
#else  /* NON_BLOCKING_CONNECT */
#define IF_NON_BLOCKING_CONNECT(s)
#endif	/* NON_BLOCKING_CONNECT */

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

/* The largest descriptor currently in use for keyboard input.  */
static int max_keyboard_desc;

/* The largest descriptor currently in use for gpm mouse input.  */
static int max_gpm_desc;

/* 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;

/* 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.  */

/* Don't make static; need to access externally.  */
int proc_buffered_char[MAXDESC];

/* Table of `struct coding-system' for each process.  */
static struct coding_system *proc_decode_coding_system[MAXDESC];
static struct coding_system *proc_encode_coding_system[MAXDESC];

#ifdef DATAGRAM_SOCKETS
/* Table of `partner address' for datagram sockets.  */
struct sockaddr_and_len {
  struct sockaddr *sa;
  int len;
} datagram_address[MAXDESC];
#define DATAGRAM_CHAN_P(chan)	(datagram_address[chan].sa != 0)
#define DATAGRAM_CONN_P(proc)	(PROCESSP (proc) && datagram_address[XPROCESS (proc)->infd].sa != 0)
#else
#define DATAGRAM_CHAN_P(chan)	(0)
#define DATAGRAM_CONN_P(proc)	(0)
#endif

/* Maximum number of bytes to send to a pty without an eof.  */
static int pty_max_bytes;

#ifdef HAVE_PTYS
#ifdef HAVE_PTY_H
#include <pty.h>
#endif
/* The file name of the pty opened by allocate_pty.  */

static char pty_name[24];
#endif

/* Compute the Lisp form of the process status, p->status, from
   the numeric status that was returned by `wait'.  */

static Lisp_Object status_convert (int);

static void
update_status (struct Lisp_Process *p)
{
  eassert (p->raw_status_new);
  p->status = status_convert (p->raw_status);
  p->raw_status_new = 0;
}

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

static Lisp_Object
status_convert (int 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.  */

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

  if (SYMBOLP (l))
    {
      *symbol = l;
      *code = 0;
      *coredump = 0;
    }
  else
    {
      *symbol = XCAR (l);
      tem = XCDR (l);
      *code = XFASTINT (XCAR (tem));
      tem = XCDR (tem);
      *coredump = !NILP (tem);
    }
}

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

static Lisp_Object
status_message (struct Lisp_Process *p)
{
  Lisp_Object status = p->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;
      synchronize_system_messages_locale ();
      signame = strsignal (code);
      if (signame == 0)
	string = build_string ("unknown");
      else
	{
	  int c1, c2;

	  string = make_unibyte_string (signame, strlen (signame));
	  if (! NILP (Vlocale_coding_system))
	    string = (code_convert_string_norecord
		      (string, Vlocale_coding_system, 0));
	  c1 = STRING_CHAR ((char *) SDATA (string));
	  c2 = DOWNCASE (c1);
	  if (c1 != c2)
	    Faset (string, make_number (0), make_number (c2));
	}
      string2 = build_string (coredump ? " (core dumped)\n" : "\n");
      return concat2 (string, string2);
    }
  else if (EQ (symbol, Qexit))
    {
      if (NETCONN1_P (p))
	return build_string (code == 0 ? "deleted\n" : "connection broken by remote peer\n");
      if (code == 0)
	return build_string ("finished\n");
      string = Fnumber_to_string (make_number (code));
      string2 = build_string (coredump ? " (core dumped)\n" : "\n");
      return concat3 (build_string ("exited abnormally with code "),
		      string, string2);
    }
  else if (EQ (symbol, Qfailed))
    {
      string = Fnumber_to_string (make_number (code));
      string2 = build_string ("\n");
      return concat3 (build_string ("failed with code "),
		      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.  */

static int
allocate_pty (void)
{
  register int c, i;
  int fd;

#ifdef PTY_ITERATION
  PTY_ITERATION
#else
  for (c = FIRST_PTY_LETTER; c <= 'z'; c++)
    for (i = 0; i < 16; i++)
#endif
      {
	struct stat stb;	/* Used in some PTY_OPEN.  */
#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 */
	{
	  { /* 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;

	    if (stat (pty_name, &stb) < 0)
	      {
		failed_count++;
		if (failed_count >= 3)
		  return -1;
	      }
	    else
	      failed_count = 0;
	  }
#  ifdef O_NONBLOCK
	  fd = emacs_open (pty_name, O_RDWR | O_NONBLOCK, 0);
#  else
	  fd = emacs_open (pty_name, O_RDWR | O_NDELAY, 0);
#  endif
	}
#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 */
	    if (access (pty_name, 6) != 0)
	      {
		emacs_close (fd);
# ifndef __sgi
		continue;
# else
		return -1;
# endif /* __sgi */
	      }
	    setup_pty (fd);
	    return fd;
	  }
      }
  return -1;
}
#endif /* HAVE_PTYS */

static Lisp_Object
make_process (Lisp_Object name)
{
  register Lisp_Object val, tem, name1;
  register struct Lisp_Process *p;
  char suffix[10];
  register int i;

  p = allocate_process ();

  p->infd = -1;
  p->outfd = -1;
  p->tick = 0;
  p->update_tick = 0;
  p->pid = 0;
  p->pty_flag = 0;
  p->raw_status_new = 0;
  p->status = Qrun;
  p->mark = Fmake_marker ();
  p->kill_without_query = 0;

#ifdef ADAPTIVE_READ_BUFFERING
  p->adaptive_read_buffering = 0;
  p->read_output_delay = 0;
  p->read_output_skip = 0;
#endif

  /* 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;
  XSETPROCESS (val, p);
  Vprocess_alist = Fcons (Fcons (name, val), Vprocess_alist);
  return val;
}

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

  pair = Frassq (proc, Vprocess_alist);
  Vprocess_alist = Fdelq (pair, Vprocess_alist);

  deactivate_process (proc);
}


DEFUN ("processp", Fprocessp, Sprocessp, 1, 1, 0,
       doc: /* Return t if OBJECT is a process.  */)
  (Lisp_Object object)
{
  return PROCESSP (object) ? Qt : Qnil;
}

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

/* 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 (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", SDATA (name));
    }
  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", SDATA (XBUFFER (obj)->name));
    }
  else
    {
      CHECK_PROCESS (obj);
      proc = obj;
    }
  return proc;
}


#ifdef SIGCHLD
/* Fdelete_process promises to immediately forget about the process, but in
   reality, Emacs needs to remember those processes until they have been
   treated by sigchld_handler; otherwise this handler would consider the
   process as being synchronous and say that the synchronous process is
   dead.  */
static Lisp_Object deleted_pid_list;
#endif

DEFUN ("delete-process", Fdelete_process, Sdelete_process, 1, 1, 0,
       doc: /* Delete PROCESS: kill it and forget about it immediately.
PROCESS may be a process, a buffer, the name of a process or buffer, or
nil, indicating the current buffer's process.  */)
  (register Lisp_Object process)
{
  register struct Lisp_Process *p;

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

  p->raw_status_new = 0;
  if (NETCONN1_P (p) || SERIALCONN1_P (p))
    {
      p->status = Fcons (Qexit, Fcons (make_number (0), Qnil));
      p->tick = ++process_tick;
      status_notify (p);
      redisplay_preserve_echo_area (13);
    }
  else if (p->infd >= 0)
    {
#ifdef SIGCHLD
      Lisp_Object symbol;
      /* Assignment to EMACS_INT stops GCC whining about limited range
	 of data type.  */
      EMACS_INT pid = p->pid;

      /* No problem storing the pid here, as it is still in Vprocess_alist.  */
      deleted_pid_list = Fcons (make_fixnum_or_float (pid),
				/* GC treated elements set to nil.  */
				Fdelq (Qnil, deleted_pid_list));
      /* If the process has already signaled, remove it from the list.  */
      if (p->raw_status_new)
	update_status (p);
      symbol = p->status;
      if (CONSP (p->status))
	symbol = XCAR (p->status);
      if (EQ (symbol, Qsignal) || EQ (symbol, Qexit))
	deleted_pid_list
	  = Fdelete (make_fixnum_or_float (pid), deleted_pid_list);
      else
#endif
	{
	  Fkill_process (process, Qnil);
	  /* Do this now, since remove_process will make sigchld_handler do nothing.  */
	  p->status
	    = Fcons (Qsignal, Fcons (make_number (SIGKILL), Qnil));
	  p->tick = ++process_tick;
	  status_notify (p);
	  redisplay_preserve_echo_area (13);
	}
    }
  remove_process (process);
  return Qnil;
}

DEFUN ("process-status", Fprocess_status, Sprocess_status, 1, 1, 0,
       doc: /* Return the status of PROCESS.
The returned value is one of the following symbols:
run  -- for a process that is running.
stop -- for a process stopped but continuable.
exit -- for a process that has exited.
signal -- for a process that has got a fatal signal.
open -- for a network stream connection that is open.
listen -- for a network stream server that is listening.
closed -- for a network stream connection that is closed.
connect -- when waiting for a non-blocking connection to complete.
failed -- when a non-blocking connection has failed.
nil -- if arg is a process name and no such process exists.
PROCESS may be a process, a buffer, the name of a process, or
nil, indicating the current buffer's process.  */)
  (register Lisp_Object process)
{
  register struct Lisp_Process *p;
  register Lisp_Object status;

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

  if (NILP (process))
    return process;

  p = XPROCESS (process);
  if (p->raw_status_new)
    update_status (p);
  status = p->status;
  if (CONSP (status))
    status = XCAR (status);
  if (NETCONN1_P (p) || SERIALCONN1_P (p))
    {
      if (EQ (status, Qexit))
	status = Qclosed;
      else if (EQ (p->command, Qt))
	status = Qstop;
      else if (EQ (status, Qrun))
	status = Qopen;
    }
  return status;
}

DEFUN ("process-exit-status", Fprocess_exit_status, Sprocess_exit_status,
       1, 1, 0,
       doc: /* Return the exit status of PROCESS or the signal number that killed it.
If PROCESS has not yet exited or died, return 0.  */)
  (register Lisp_Object process)
{
  CHECK_PROCESS (process);
  if (XPROCESS (process)->raw_status_new)
    update_status (XPROCESS (process));
  if (CONSP (XPROCESS (process)->status))
    return XCAR (XCDR (XPROCESS (process)->status));
  return make_number (0);
}

DEFUN ("process-id", Fprocess_id, Sprocess_id, 1, 1, 0,
       doc: /* Return the process id of PROCESS.
This is the pid of the external process which PROCESS uses or talks to.
For a network connection, this value is nil.  */)
  (register Lisp_Object process)
{
  /* Assignment to EMACS_INT stops GCC whining about limited range of
     data type.  */
  EMACS_INT pid;

  CHECK_PROCESS (process);
  pid = XPROCESS (process)->pid;
  return (pid ? make_fixnum_or_float (pid) : Qnil);
}

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

DEFUN ("process-command", Fprocess_command, Sprocess_command, 1, 1, 0,
       doc: /* Return the command that was executed to start PROCESS.
This is a list of strings, the first string being the program executed
and the rest of the strings being the arguments given to it.
For a network or serial process, this is nil (process is running) or t
\(process is stopped).  */)
  (register Lisp_Object process)
{
  CHECK_PROCESS (process);
  return XPROCESS (process)->command;
}

DEFUN ("process-tty-name", Fprocess_tty_name, Sprocess_tty_name, 1, 1, 0,
       doc: /* Return the name of the terminal PROCESS uses, or nil if none.
This is the terminal that the process itself reads and writes on,
not the name of the pty that Emacs uses to talk with that terminal.  */)
  (register Lisp_Object process)
{
  CHECK_PROCESS (process);
  return XPROCESS (process)->tty_name;
}

DEFUN ("set-process-buffer", Fset_process_buffer, Sset_process_buffer,
       2, 2, 0,
       doc: /* Set buffer associated with PROCESS to BUFFER (a buffer, or nil).  */)
  (register Lisp_Object process, Lisp_Object buffer)
{
  struct Lisp_Process *p;

  CHECK_PROCESS (process);
  if (!NILP (buffer))
    CHECK_BUFFER (buffer);
  p = XPROCESS (process);
  p->buffer = buffer;
  if (NETCONN1_P (p) || SERIALCONN1_P (p))
    p->childp = Fplist_put (p->childp, QCbuffer, buffer);
  setup_process_coding_systems (process);
  return buffer;
}

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

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

DEFUN ("set-process-filter", Fset_process_filter, Sset_process_filter,
       2, 2, 0,
       doc: /* Give PROCESS the filter function FILTER; nil means no filter.
A value of t means stop accepting output from the process.

When a process has a filter, its buffer is not used for output.
Instead, each time it does output, the entire string of output is
passed to the filter.

The filter gets two arguments: the process and the string of output.
The string argument is normally a multibyte string, except:
- if the process' input coding system is no-conversion or raw-text,
  it is a unibyte string (the non-converted input), or else
- if `default-enable-multibyte-characters' is nil, it is a unibyte
  string (the result of converting the decoded input multibyte
  string to unibyte with `string-make-unibyte').  */)
  (register Lisp_Object process, Lisp_Object filter)
{
  struct Lisp_Process *p;

  CHECK_PROCESS (process);
  p = XPROCESS (process);

  /* Don't signal an error if the process' input file descriptor
     is closed.  This could make debugging Lisp more difficult,
     for example when doing something like

     (setq process (start-process ...))
     (debug)
     (set-process-filter process ...)  */

  if (p->infd >= 0)
    {
      if (EQ (filter, Qt) && !EQ (p->status, Qlisten))
	{
	  FD_CLR (p->infd, &input_wait_mask);
	  FD_CLR (p->infd, &non_keyboard_wait_mask);
	}
      else if (EQ (p->filter, Qt)
	       /* Network or serial process not stopped:  */
	       && !EQ (p->command, Qt))
	{
	  FD_SET (p->infd, &input_wait_mask);
	  FD_SET (p->infd, &non_keyboard_wait_mask);
	}
    }

  p->filter = filter;
  if (NETCONN1_P (p) || SERIALCONN1_P (p))