emacsserver.c   [plain text]

/* Communication subprocess for GNU Emacs acting as server.
   Copyright (C) 1986, 1987, 1992, 1994, 1999 Free Software Foundation, Inc.

This file is part of GNU Emacs.

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

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

You should have received a copy of the GNU General Public License
along with GNU Emacs; see the file COPYING.  If not, write to
the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA.  */


/* The GNU Emacs edit server process is run as a subprocess of Emacs
   under control of the file lisp/server.el.
   This program accepts communication from client (program emacsclient.c)
   and passes their commands (consisting of keyboard characters)
   up to the Emacs which then executes them.  */

#define NO_SHORTNAMES
#include <../src/config.h>
#include <signal.h>
#undef signal

#if !defined (HAVE_SOCKETS) && !defined (HAVE_SYSVIPC)
#include <stdio.h>

int
main ()
{
  fprintf (stderr, "Sorry, the Emacs server is supported only on systems\n");
  fprintf (stderr, "with Berkeley sockets or System V IPC.\n");
  exit (1);
}

#else /* HAVE_SOCKETS or HAVE_SYSVIPC */

void perror_1 ();
void fatal_error ();

#if defined (HAVE_SOCKETS) && ! defined (NO_SOCKETS_IN_FILE_SYSTEM)
/* BSD code is very different from SYSV IPC code */

#include <sys/types.h>
#include <sys/file.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <stdio.h>
#include <errno.h>
#include <sys/stat.h>

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

#ifndef errno
extern int errno;
#endif

/* Copied from src/process.c */
#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 */

/* This is the file name of the socket that we made.  */

char *socket_name;

/* Name of this program.  */

char *progname;

/* Handle fatal signals.  */

/* This is the handler.  */

SIGTYPE
delete_socket (sig)
     int sig;
{
  signal (sig, SIG_DFL);
  unlink (socket_name);
  kill (getpid (), sig);
}

/* Set up to handle all the signals.  */

void
handle_signals ()
{
  signal (SIGHUP, delete_socket);
  signal (SIGINT, delete_socket);
  signal (SIGQUIT, delete_socket);
  signal (SIGILL, delete_socket);
  signal (SIGTRAP, delete_socket);
#ifdef SIGABRT
  signal (SIGABRT, delete_socket);
#endif
#ifdef SIGHWE
  signal (SIGHWE, delete_socket);
#endif
#ifdef SIGPRE
  signal (SIGPRE, delete_socket);
#endif
#ifdef SIGORE
  signal (SIGORE, delete_socket);
#endif
#ifdef SIGUME
  signal (SIGUME, delete_socket);
#endif
#ifdef SIGDLK
  signal (SIGDLK, delete_socket);
#endif
#ifdef SIGCPULIM
  signal (SIGCPULIM, delete_socket);
#endif
#ifdef SIGIOT
  /* This is missing on some systems - OS/2, for example.  */
  signal (SIGIOT, delete_socket);
#endif
#ifdef SIGEMT
  signal (SIGEMT, delete_socket);
#endif
  signal (SIGFPE, delete_socket);
#ifdef SIGBUS
  signal (SIGBUS, delete_socket);
#endif
  signal (SIGSEGV, delete_socket);
#ifdef SIGSYS
  signal (SIGSYS, delete_socket);
#endif
  signal (SIGTERM, delete_socket);
#ifdef SIGXCPU
  signal (SIGXCPU, delete_socket);
#endif
#ifdef SIGXFSZ
  signal (SIGXFSZ, delete_socket);
#endif /* SIGXFSZ */

#ifdef AIX
/* 20 is SIGCHLD, 21 is SIGTTIN, 22 is SIGTTOU.  */
  signal (SIGXCPU, delete_socket);
#ifndef _I386
  signal (SIGIOINT, delete_socket);
#endif
  signal (SIGGRANT, delete_socket);
  signal (SIGRETRACT, delete_socket);
  signal (SIGSOUND, delete_socket);
  signal (SIGMSG, delete_socket);
#endif /* AIX */
}

/* Print error message.  `s1' is printf control string, `s2' is arg for it. */
void
error (s1, s2)
     char *s1, *s2;
{
  fprintf (stderr, "%s: ", progname);
  fprintf (stderr, s1, s2);
  fprintf (stderr, "\n");
}

/* Print error message and exit.  */
void
fatal (s1, s2)
     char *s1, *s2;
{
  error (s1, s2);
  exit (1);
}

/* Like malloc but get fatal error if memory is exhausted.  */

long *
xmalloc (size)
     unsigned int size;
{
  long *result = (long *) malloc (size);
  if (result == NULL)
    fatal ("virtual memory exhausted", 0);
  return result;
}

int
main (argc, argv)
     int argc;
     char **argv;
{
  char *system_name;
  int system_name_length;
  int s, infd;
#ifdef SOCKLEN_TYPE
  SOCKLEN_TYPE fromlen;
#else
  size_t fromlen;
#endif
  struct sockaddr_un server, fromunix;
#ifdef SERVER_HOME_DIR
  char *homedir;
#endif
  char *str, string[BUFSIZ], code[BUFSIZ];
  FILE *infile;
  FILE **openfiles;
  int openfiles_size;
  struct stat statbuf;

#ifndef convex
  char *getenv ();
#endif

  progname = argv[0];

  openfiles_size = 20;
  openfiles = (FILE **) malloc (openfiles_size * sizeof (FILE *));
  if (openfiles == 0)
    abort ();

  /* 
   * Open up an AF_UNIX socket in this person's home directory
   */

  if ((s = socket (AF_UNIX, SOCK_STREAM, 0)) < 0)
    {
      perror_1 ("socket");
      exit (1);
    }
  server.sun_family = AF_UNIX;

  system_name_length = 32;
  while (1)
    {
      system_name = (char *) xmalloc (system_name_length + 1);

      /* system_name must be null-terminated string.  */
      system_name[system_name_length] = '\0';

      if (gethostname (system_name, system_name_length) == 0)
	break;

      free (system_name);
      system_name_length *= 2;
    }

#ifndef SERVER_HOME_DIR
  sprintf (server.sun_path, "/tmp/esrv%d-%s", geteuid (), system_name);

  if (unlink (server.sun_path) == -1 && errno != ENOENT)
    {
      perror_1 ("unlink");
      exit (1);
    }
#else  
  if ((homedir = getenv ("HOME")) == NULL)
    fatal_error ("No home directory\n");

  strcpy (server.sun_path, homedir);
  strcat (server.sun_path, "/.emacs-server-");
  strcat (server.sun_path, system_name);
  /* Delete anyone else's old server.  */
  unlink (server.sun_path);
#endif

  /* Save the socket name so we can delete it.  */
  socket_name = (char *) xmalloc (strlen (server.sun_path) + 1);
  strcpy (socket_name, server.sun_path);

  handle_signals ();

  if (bind (s, (struct sockaddr *) &server, strlen (server.sun_path) + 2) < 0)
    {
      perror_1 ("bind");
      exit (1);
    }
  /* Only this user can send commands to this Emacs.  */
  if (stat (server.sun_path, &statbuf) < 0)
    {
      perror_1 ("bind");
      exit (1);
    }

  chmod (server.sun_path, statbuf.st_mode & 0600);
  /*
   * Now, just wait for everything to come in..
   */
  if (listen (s, 5) < 0)
    {
      perror_1 ("listen");
      exit (1);
    }

  /* Disable sigpipes in case luser kills client... */
  signal (SIGPIPE, SIG_IGN);
  for (;;)
    {
      SELECT_TYPE rmask;
      FD_ZERO (&rmask);
      FD_SET (0, &rmask);
      FD_SET (s, &rmask);
      if (select (s + 1, &rmask, 0, 0, 0) < 0)
	perror_1 ("select");
      if (FD_ISSET (s, &rmask))	/* client sends list of filenames */
	{
	  fromlen = sizeof (fromunix);
	  fromunix.sun_family = AF_UNIX;
	  infd = accept (s, (struct sockaddr *) &fromunix, &fromlen);
	  if (infd < 0)
	    {
	      if (errno == EMFILE || errno == ENFILE)
		fprintf (stderr, "Error: too many clients.\n");
	      else
		perror_1 ("accept");
	      continue;
	    }

	  if (infd >= openfiles_size)
	    {
	      openfiles_size *= 2;
	      openfiles = (FILE **) realloc (openfiles,
					     openfiles_size * sizeof (FILE *));
	      if (openfiles == 0)
		abort ();
	    }

	  infile = fdopen (infd, "r+"); /* open stream */
	  if (infile == NULL)
	    {
	      fprintf (stderr, "Error: too many clients.\n");
	      write (infd, "Too many clients.\n", 18);
	      close (infd);		/* Prevent descriptor leak.. */
	      continue;
	    }
	  str = fgets (string, BUFSIZ, infile);
	  if (str == NULL)
	    {
	      perror_1 ("fgets");
	      close (infd);		/* Prevent descriptor leak.. */
	      continue;
	    }
	  openfiles[infd] = infile;
	  printf ("Client: %d %s", infd, string);
	  /* If what we read did not end in a newline,
	     it means there is more.  Keep reading from the socket
	     and outputting to Emacs, until we get the newline.  */
	  while (string[strlen (string) - 1] != '\n')
	    {
	      if (fgets (string, BUFSIZ, infile) == 0)
		break;
	      printf ("%s", string);
	    }
	  fflush (stdout);
	  fflush (infile);
	  continue;
	}
      else if (FD_ISSET (0, &rmask)) /* emacs sends codeword, fd, and string message */
	{
	  /* Read command codeword and fd */
	  clearerr (stdin);
	  scanf ("%s %d%*c", code, &infd);
	  if (ferror (stdin) || feof (stdin))
	    fatal_error ("server: error reading from standard input\n");

	  /* Transfer text from Emacs to the client, up to a newline.  */
	  infile = openfiles[infd];
	  rewind (infile);
	  while (1)
	    {
	      if (fgets (string, BUFSIZ, stdin) == 0)
		break;
	      fprintf (infile, "%s", string);
	      if (string[strlen (string) - 1] == '\n')
		break;
	    }
	  fflush (infile);

	  /* If command is close, close connection to client.  */
	  if (strncmp (code, "Close:", 6) == 0) 
	    if (infd > 2) 
	      {
		fclose (infile);
		close (infd);
	      }
	  continue;
	} 
    }
}

#else  /* This is the SYSV IPC section */

#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/msg.h>
#include <setjmp.h>
#include <errno.h>
#include <sys/utsname.h>

struct utsname system_name;

#ifndef errno
extern int errno;
#endif

jmp_buf msgenv;

SIGTYPE
msgcatch ()
{
  longjmp (msgenv, 1);
}


/* "THIS has to be fixed.  Remember, stderr may not exist...-rlk."
   Incorrect.  This program runs as an inferior of Emacs.
   Its stderr always exists--rms.  */
#include <stdio.h>

int
main ()
{
  int s, infd, fromlen, ioproc;
  key_t key;
  struct msgbuf * msgp =
    (struct msgbuf *) malloc (sizeof *msgp + BUFSIZ);
  struct msqid_ds msg_st;
  int p;
  char *homedir, *getenv ();
  char string[BUFSIZ];
  FILE *infile;

  /*
   * Create a message queue using ~/.emacs-server as the path for ftok
   */
  if ((homedir = getenv ("HOME")) == NULL)
    fatal_error ("No home directory\n");

  strcpy (string, homedir);
#ifndef HAVE_LONG_FILE_NAMES
  /* If file names are short, we can't fit the host name.  */
  strcat (string, "/.emacs-server");
#else
  strcat (string, "/.emacs-server-");
  uname (&system_name);
  strcat (string, system_name.nodename);
#endif
  creat (string, 0600);
  key = ftok (string, 1);	/* unlikely to be anyone else using it */
  s = msgget (key, 0600 | IPC_CREAT);
  if (s == -1)
    {
      perror_1 ("msgget");
      exit (1);
    }

  /* Fork so we can close connection even if parent dies */
  p = fork ();
  if (setjmp (msgenv))
    {
      msgctl (s, IPC_RMID, 0);
      if (p > 0)
	kill (p, SIGKILL);
      exit (0);
    }
  signal (SIGTERM, msgcatch);
  signal (SIGINT, msgcatch);
  signal (SIGHUP, msgcatch);
  if (p > 0)
    {
      /* This is executed in the original process that did the fork above.  */
      /* Get pid of Emacs itself.  */
      p = getppid ();
      setpgrp ();		/* Gnu kills process group on exit */
      while (1)
	{
	  /* Is Emacs still alive?  */
	  if (kill (p, 0) < 0)
	    {
	      msgctl (s, IPC_RMID, 0);
	      exit (0);
	    }
	  sleep (10);
	}
    }

  /* This is executed in the child made by forking above.
     Call it c1.  Make another process, ioproc.  */

  ioproc = fork ();
  if (ioproc == 0)
    {
      /* In process ioproc, wait for text from Emacs,
	 and send it to the process c1.
	 This way, c1 only has to wait for one source of input.  */
      while (fgets (msgp->mtext, BUFSIZ, stdin))
	{
	  msgp->mtype = 1;
	  msgsnd (s, msgp, strlen (msgp->mtext) + 1, 0);
	}
      exit (1);
    }

  /* In the process c1,
     listen for messages from clients and pass them to Emacs.  */
  while (1)
    {
      if ((fromlen = msgrcv (s, msgp, BUFSIZ - 1, 1, 0)) < 0)
        {
#ifdef EINTR
	  if (errno == EINTR)
	    continue;
#endif
	  perror_1 ("msgrcv");
	  exit (1);
        }
      else
        {
	  msgctl (s, IPC_STAT, &msg_st);

	  /* Distinguish whether the message came from a client, or from
	     ioproc.  */
	  if (msg_st.msg_lspid == ioproc)
	    {
	      char code[BUFSIZ];
	      int inproc;

	      /* Message from ioproc: tell a client we are done.  */
	      msgp->mtext[strlen (msgp->mtext)-1] = 0;
	      sscanf (msgp->mtext, "%s %d", code, &inproc);
	      msgp->mtype = inproc;
	      msgsnd (s, msgp, strlen (msgp->mtext) + 1, 0);
	      continue;
	    }

	  /* This is a request from a client: copy to stdout
	     so that Emacs will get it.  Include msg_lspid
	     so server.el can tell us where to send the reply.  */
	  strncpy (string, msgp->mtext, fromlen);
	  string[fromlen] = 0;	/* make sure */
	  /* Newline is part of string.. */
	  printf ("Client: %d %s", msg_st.msg_lspid, string);
	  fflush (stdout);
	}
    }
}

#endif /* HAVE_SYSVIPC */


/* This is like perror but puts `Error: ' at the beginning.  */

void
perror_1 (string)
     char *string;
{
  char *copy = (char *) malloc (strlen (string) + 8);
  if (copy == 0)
    fatal_error ("Virtual memory exhausted");

  strcpy (copy, "Error: ");
  strcat (copy, string);
  perror (copy);
}

void
fatal_error (string)
     char *string;
{
  fprintf (stderr, "%s", "Error: ");
  fprintf (stderr, string);
  exit (1);
}
#endif /* HAVE_SOCKETS or HAVE_SYSVIPC */