lib-src/emacsserver.c

   1 /* Communication subprocess for GNU Emacs acting as server.
   2    Copyright (C) 1986, 1987, 1992, 1994 Free Software Foundation, Inc.
   3
   4 This file is part of GNU Emacs.
   5
   6 GNU Emacs is free software; you can redistribute it and/or modify
   7 it under the terms of the GNU General Public License as published by
   8 the Free Software Foundation; either version 2, or (at your option)
   9 any later version.
  10
  11 GNU Emacs is distributed in the hope that it will be useful,
  12 but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 GNU General Public License for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GNU Emacs; see the file COPYING.  If not, write to
  18 the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */
  19
  20
  21 /* The GNU Emacs edit server process is run as a subprocess of Emacs
  22    under control of the file lisp/server.el.
  23    This program accepts communication from client (program emacsclient.c)
  24    and passes their commands (consisting of keyboard characters)
  25    up to the Emacs which then executes them.  */
  26
  27 #define NO_SHORTNAMES
  28 #include <../src/config.h>
  29 #undef read
  30 #undef write
  31 #undef open
  32 #undef close
  33 #undef signal
  34
  35 #if !defined (HAVE_SOCKETS) && !defined (HAVE_SYSVIPC)
  36 #include <stdio.h>
  37
  38 main ()
  39 {
  40   fprintf (stderr, "Sorry, the Emacs server is supported only on systems\n");
  41   fprintf (stderr, "with Berkeley sockets or System V IPC.\n");
  42   exit (1);
  43 }
  44
  45 #else /* HAVE_SOCKETS or HAVE_SYSVIPC */
  46
  47 #if defined (HAVE_SOCKETS) && ! defined (NO_SOCKETS_IN_FILE_SYSTEM)
  48 /* BSD code is very different from SYSV IPC code */
  49
  50 #include <sys/types.h>
  51 #include <sys/file.h>
  52 #include <sys/socket.h>
  53 #include <sys/signal.h>
  54 #include <sys/un.h>
  55 #include <stdio.h>
  56 #include <errno.h>
  57
  58 extern int errno;
  59
  60 /* Copied from src/process.c */
  61 #ifdef FD_SET
  62 /* We could get this from param.h, but better not to depend on finding that.
  63    And better not to risk that it might define other symbols used in this
  64    file.  */
  65 #ifdef FD_SETSIZE
  66 #define MAXDESC FD_SETSIZE
  67 #else
  68 #define MAXDESC 64
  69 #endif
  70 #define SELECT_TYPE fd_set
  71 #else /* no FD_SET */
  72 #define MAXDESC 32
  73 #define SELECT_TYPE int
  74
  75 /* Define the macros to access a single-int bitmap of descriptors.  */
  76 #define FD_SET(n, p) (*(p) |= (1 << (n)))
  77 #define FD_CLR(n, p) (*(p) &= ~(1 << (n)))
  78 #define FD_ISSET(n, p) (*(p) & (1 << (n)))
  79 #define FD_ZERO(p) (*(p) = 0)
  80 #endif /* no FD_SET */
  81
  82 main ()
  83 {
  84   char system_name[32];
  85   int s, infd, fromlen;
  86   struct sockaddr_un server, fromunix;
  87   char *homedir;
  88   char *str, string[BUFSIZ], code[BUFSIZ];
  89   FILE *infile;
  90   FILE **openfiles;
  91   int openfiles_size;
  92
  93 #ifndef convex
  94   char *getenv ();
  95 #endif
  96
  97   openfiles_size = 20;
  98   openfiles = (FILE **) malloc (openfiles_size * sizeof (FILE *));
  99   if (openfiles == 0)
 100     abort ();
 101
 102   /*
 103    * Open up an AF_UNIX socket in this person's home directory
 104    */
 105
 106   if ((s = socket (AF_UNIX, SOCK_STREAM, 0)) < 0)
 107     {
 108       perror_1 ("socket");
 109       exit (1);
 110     }
 111   server.sun_family = AF_UNIX;
 112 #ifndef SERVER_HOME_DIR
 113   gethostname (system_name, sizeof (system_name));
 114   sprintf (server.sun_path, "/tmp/esrv%d-%s", geteuid (), system_name);
 115
 116   if (unlink (server.sun_path) == -1 && errno != ENOENT)
 117     {
 118       perror_1 ("unlink");
 119       exit (1);
 120     }
 121 #else
 122   if ((homedir = getenv ("HOME")) == NULL)
 123     fatal_error ("No home directory\n");
 124
 125   strcpy (server.sun_path, homedir);
 126   strcat (server.sun_path, "/.emacs-server-");
 127   gethostname (system_name, sizeof (system_name));
 128   strcat (server.sun_path, system_name);
 129   /* Delete anyone else's old server.  */
 130   unlink (server.sun_path);
 131 #endif
 132
 133   if (bind (s, (struct sockaddr *) &server, strlen (server.sun_path) + 2) < 0)
 134     {
 135       perror_1 ("bind");
 136       exit (1);
 137     }
 138   /* Only this user can send commands to this Emacs.  */
 139   chmod (server.sun_path, 0600);
 140   /*
 141    * Now, just wait for everything to come in..
 142    */
 143   if (listen (s, 5) < 0)
 144     {
 145       perror_1 ("listen");
 146       exit (1);
 147     }
 148
 149   /* Disable sigpipes in case luser kills client... */
 150   signal (SIGPIPE, SIG_IGN);
 151   for (;;)
 152     {
 153       SELECT_TYPE rmask;
 154       FD_ZERO (&rmask);
 155       FD_SET (0, &rmask);
 156       FD_SET (s, &rmask);
 157       if (select (s + 1, &rmask, 0, 0, 0) < 0)
 158         perror_1 ("select");
 159       if (FD_ISSET (s, &rmask)) /* client sends list of filenames */
 160         {
 161           fromlen = sizeof (fromunix);
 162           fromunix.sun_family = AF_UNIX;
 163           infd = accept (s, (struct sockaddr *) &fromunix, &fromlen);
 164           if (infd < 0)
 165             {
 166               if (errno == EMFILE || errno == ENFILE)
 167                 fprintf (stderr, "Error: too many clients.\n");
 168               else
 169                 perror_1 ("accept");
 170               continue;
 171             }
 172
 173           if (infd >= openfiles_size)
 174             {
 175               openfiles_size *= 2;
 176               openfiles = (FILE **) realloc (openfiles,
 177                                              openfiles_size * sizeof (FILE *));
 178               if (openfiles == 0)
 179                 abort ();
 180             }
 181
 182           infile = fdopen (infd, "r+"); /* open stream */
 183           if (infile == NULL)
 184             {
 185               fprintf (stderr, "Error: too many clients.\n");
 186               write (infd, "Too many clients.\n", 18);
 187               close (infd);             /* Prevent descriptor leak.. */
 188               continue;
 189             }
 190           str = fgets (string, BUFSIZ, infile);
 191           if (str == NULL)
 192             {
 193               perror_1 ("fgets");
 194               close (infd);             /* Prevent descriptor leak.. */
 195               continue;
 196             }
 197           openfiles[infd] = infile;
 198           printf ("Client: %d %s", infd, string);
 199           /* If what we read did not end in a newline,
 200              it means there is more.  Keep reading from the socket
 201              and outputting to Emacs, until we get the newline.  */
 202           while (string[strlen (string) - 1] != '\n')
 203             {
 204               if (fgets (string, BUFSIZ, infile) == 0)
 205                 break;
 206               printf ("%s", string);
 207             }
 208           fflush (stdout);
 209           fflush (infile);
 210           continue;
 211         }
 212       else if (FD_ISSET (0, &rmask)) /* emacs sends codeword, fd, and string message */
 213         {
 214           /* Read command codeword and fd */
 215           clearerr (stdin);
 216           scanf ("%s %d%*c", code, &infd);
 217           if (ferror (stdin) || feof (stdin))
 218             fatal_error ("server: error reading from standard input\n");
 219
 220           /* Transfer text from Emacs to the client, up to a newline.  */
 221           infile = openfiles[infd];
 222           while (1)
 223             {
 224               if (fgets (string, BUFSIZ, stdin) == 0)
 225                 break;
 226               fprintf (infile, "%s", string);
 227               if (string[strlen (string) - 1] == '\n')
 228                 break;
 229             }
 230           fflush (infile);
 231
 232           /* If command is close, close connection to client.  */
 233           if (strncmp (code, "Close:", 6) == 0)
 234             if (infd > 2)
 235               {
 236                 fclose (infile);
 237                 close (infd);
 238               }
 239           continue;
 240         }
 241     }
 242 }
 243
 244 #else  /* This is the SYSV IPC section */
 245
 246 #include <sys/types.h>
 247 #include <sys/signal.h>
 248 #include <sys/ipc.h>
 249 #include <sys/msg.h>
 250 #include <setjmp.h>
 251 #include <errno.h>
 252 #include <sys/utsname.h>
 253
 254 struct utsname system_name;
 255
 256 #ifndef errno
 257 extern int errno;
 258 #endif
 259
 260 jmp_buf msgenv;
 261
 262 SIGTYPE
 263 msgcatch ()
 264 {
 265   longjmp (msgenv, 1);
 266 }
 267
 268
 269 /* "THIS has to be fixed.  Remember, stderr may not exist...-rlk."
 270    Incorrect.  This program runs as an inferior of Emacs.
 271    Its stderr always exists--rms.  */
 272 #include <stdio.h>
 273
 274 main ()
 275 {
 276   int s, infd, fromlen, ioproc;
 277   key_t key;
 278   struct msgbuf * msgp =
 279     (struct msgbuf *) malloc (sizeof *msgp + BUFSIZ);
 280   struct msqid_ds msg_st;
 281   int p;
 282   char *homedir, *getenv ();
 283   char string[BUFSIZ];
 284   FILE *infile;
 285
 286   /*
 287    * Create a message queue using ~/.emacs-server as the path for ftok
 288    */
 289   if ((homedir = getenv ("HOME")) == NULL)
 290     fatal_error ("No home directory\n");
 291
 292   strcpy (string, homedir);
 293 #ifndef HAVE_LONG_FILE_NAMES
 294   /* If file names are short, we can't fit the host name.  */
 295   strcat (string, "/.emacs-server");
 296 #else
 297   strcat (string, "/.emacs-server-");
 298   uname (&system_name);
 299   strcat (string, system_name.nodename);
 300 #endif
 301   creat (string, 0600);
 302   key = ftok (string, 1);       /* unlikely to be anyone else using it */
 303   s = msgget (key, 0600 | IPC_CREAT);
 304   if (s == -1)
 305     {
 306       perror_1 ("msgget");
 307       exit (1);
 308     }
 309
 310   /* Fork so we can close connection even if parent dies */
 311   p = fork ();
 312   if (setjmp (msgenv))
 313     {
 314       msgctl (s, IPC_RMID, 0);
 315       if (p > 0)
 316         kill (p, SIGKILL);
 317       exit (0);
 318     }
 319   signal (SIGTERM, msgcatch);
 320   signal (SIGINT, msgcatch);
 321   signal (SIGHUP, msgcatch);
 322   if (p > 0)
 323     {
 324       /* This is executed in the original process that did the fork above.  */
 325       /* Get pid of Emacs itself.  */
 326       p = getppid ();
 327       setpgrp ();               /* Gnu kills process group on exit */
 328       while (1)
 329         {
 330           /* Is Emacs still alive?  */
 331           if (kill (p, 0) < 0)
 332             {
 333               msgctl (s, IPC_RMID, 0);
 334               exit (0);
 335             }
 336           sleep (10);
 337         }
 338     }
 339
 340   /* This is executed in the child made by forking above.
 341      Call it c1.  Make another process, ioproc.  */
 342
 343   ioproc = fork ();
 344   if (ioproc == 0)
 345     {
 346       /* In process ioproc, wait for text from Emacs,
 347          and send it to the process c1.
 348          This way, c1 only has to wait for one source of input.  */
 349       while (fgets (msgp->mtext, BUFSIZ, stdin))
 350         {
 351           msgp->mtype = 1;
 352           msgsnd (s, msgp, strlen (msgp->mtext) + 1, 0);
 353         }
 354       exit (1);
 355     }
 356
 357   /* In the process c1,
 358      listen for messages from clients and pass them to Emacs.  */
 359   while (1)
 360     {
 361       if ((fromlen = msgrcv (s, msgp, BUFSIZ - 1, 1, 0)) < 0)
 362         {
 363 #ifdef EINTR
 364           if (errno == EINTR)
 365             continue;
 366 #endif
 367           perror_1 ("msgrcv");
 368           exit (1);
 369         }
 370       else
 371         {
 372           msgctl (s, IPC_STAT, &msg_st);
 373
 374           /* Distinguish whether the message came from a client, or from
 375              ioproc.  */
 376           if (msg_st.msg_lspid == ioproc)
 377             {
 378               char code[BUFSIZ];
 379               int inproc;
 380
 381               /* Message from ioproc: tell a client we are done.  */
 382               msgp->mtext[strlen (msgp->mtext)-1] = 0;
 383               sscanf (msgp->mtext, "%s %d", code, &inproc);
 384               msgp->mtype = inproc;
 385               msgsnd (s, msgp, strlen (msgp->mtext) + 1, 0);
 386               continue;
 387             }
 388
 389           /* This is a request from a client: copy to stdout
 390              so that Emacs will get it.  Include msg_lspid
 391              so server.el can tell us where to send the reply.  */
 392           strncpy (string, msgp->mtext, fromlen);
 393           string[fromlen] = 0;  /* make sure */
 394           /* Newline is part of string.. */
 395           printf ("Client: %d %s", msg_st.msg_lspid, string);
 396           fflush (stdout);
 397         }
 398     }
 399 }
 400
 401 #endif /* HAVE_SYSVIPC */
 402
 403 #endif /* HAVE_SOCKETS or HAVE_SYSVIPC */
 404 \f
 405 /* This is like perror but puts `Error: ' at the beginning.  */
 406
 407 perror_1 (string)
 408      char *string;
 409 {
 410   char *copy = (char *) malloc (strlen (string) + 8);
 411   if (copy == 0)
 412     fatal_error ("Virtual memory exhausted");
 413
 414   strcpy (copy, "Error: ");
 415   strcat (copy, string);
 416   perror (copy);
 417 }
 418
 419 fatal_error (string)
 420      char *string;
 421 {
 422   fprintf (stderr, "%s", "Error: ");
 423   fprintf (stderr, string);
 424   exit (1);
 425 }