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, Inc., 59 Temple Place - Suite 330,
  19 Boston, MA 02111-1307, USA.  */
  20
  21
  22 /* The GNU Emacs edit server process is run as a subprocess of Emacs
  23    under control of the file lisp/server.el.
  24    This program accepts communication from client (program emacsclient.c)
  25    and passes their commands (consisting of keyboard characters)
  26    up to the Emacs which then executes them.  */
  27
  28 #define NO_SHORTNAMES
  29 #include <../src/config.h>
  30 #undef read
  31 #undef write
  32 #undef open
  33 #undef close
  34 #undef signal
  35
  36 #if !defined (HAVE_SOCKETS) && !defined (HAVE_SYSVIPC)
  37 #include <stdio.h>
  38
  39 main ()
  40 {
  41   fprintf (stderr, "Sorry, the Emacs server is supported only on systems\n");
  42   fprintf (stderr, "with Berkeley sockets or System V IPC.\n");
  43   exit (1);
  44 }
  45
  46 #else /* HAVE_SOCKETS or HAVE_SYSVIPC */
  47
  48 #if defined (HAVE_SOCKETS) && ! defined (NO_SOCKETS_IN_FILE_SYSTEM)
  49 /* BSD code is very different from SYSV IPC code */
  50
  51 #include <sys/types.h>
  52 #include <sys/file.h>
  53 #include <sys/socket.h>
  54 #include <sys/signal.h>
  55 #include <sys/un.h>
  56 #include <stdio.h>
  57 #include <errno.h>
  58 #include <sys/stat.h>
  59
  60 extern int errno;
  61
  62 /* Copied from src/process.c */
  63 #ifdef FD_SET
  64 /* We could get this from param.h, but better not to depend on finding that.
  65    And better not to risk that it might define other symbols used in this
  66    file.  */
  67 #ifdef FD_SETSIZE
  68 #define MAXDESC FD_SETSIZE
  69 #else
  70 #define MAXDESC 64
  71 #endif
  72 #define SELECT_TYPE fd_set
  73 #else /* no FD_SET */
  74 #define MAXDESC 32
  75 #define SELECT_TYPE int
  76
  77 /* Define the macros to access a single-int bitmap of descriptors.  */
  78 #define FD_SET(n, p) (*(p) |= (1 << (n)))
  79 #define FD_CLR(n, p) (*(p) &= ~(1 << (n)))
  80 #define FD_ISSET(n, p) (*(p) & (1 << (n)))
  81 #define FD_ZERO(p) (*(p) = 0)
  82 #endif /* no FD_SET */
  83
  84 int
  85 main ()
  86 {
  87   char system_name[32];
  88   int s, infd, fromlen;
  89   struct sockaddr_un server, fromunix;
  90   char *homedir;
  91   char *str, string[BUFSIZ], code[BUFSIZ];
  92   FILE *infile;
  93   FILE **openfiles;
  94   int openfiles_size;
  95   struct stat statbuf;
  96
  97 #ifndef convex
  98   char *getenv ();
  99 #endif
 100
 101   openfiles_size = 20;
 102   openfiles = (FILE **) malloc (openfiles_size * sizeof (FILE *));
 103   if (openfiles == 0)
 104     abort ();
 105
 106   /*
 107    * Open up an AF_UNIX socket in this person's home directory
 108    */
 109
 110   if ((s = socket (AF_UNIX, SOCK_STREAM, 0)) < 0)
 111     {
 112       perror_1 ("socket");
 113       exit (1);
 114     }
 115   server.sun_family = AF_UNIX;
 116 #ifndef SERVER_HOME_DIR
 117   gethostname (system_name, sizeof (system_name));
 118   sprintf (server.sun_path, "/tmp/esrv%d-%s", geteuid (), system_name);
 119
 120   if (unlink (server.sun_path) == -1 && errno != ENOENT)
 121     {
 122       perror_1 ("unlink");
 123       exit (1);
 124     }
 125 #else
 126   if ((homedir = getenv ("HOME")) == NULL)
 127     fatal_error ("No home directory\n");
 128
 129   strcpy (server.sun_path, homedir);
 130   strcat (server.sun_path, "/.emacs-server-");
 131   gethostname (system_name, sizeof (system_name));
 132   strcat (server.sun_path, system_name);
 133   /* Delete anyone else's old server.  */
 134   unlink (server.sun_path);
 135 #endif
 136
 137   if (bind (s, (struct sockaddr *) &server, strlen (server.sun_path) + 2) < 0)
 138     {
 139       perror_1 ("bind");
 140       exit (1);
 141     }
 142   /* Only this user can send commands to this Emacs.  */
 143   if (stat (server.sun_path, &statbuf) < 0)
 144     {
 145       perror_1 ("bind");
 146       exit (1);
 147     }
 148
 149   chmod (server.sun_path, statbuf.st_mode & 0600);
 150   /*
 151    * Now, just wait for everything to come in..
 152    */
 153   if (listen (s, 5) < 0)
 154     {
 155       perror_1 ("listen");
 156       exit (1);
 157     }
 158
 159   /* Disable sigpipes in case luser kills client... */
 160   signal (SIGPIPE, SIG_IGN);
 161   for (;;)
 162     {
 163       SELECT_TYPE rmask;
 164       FD_ZERO (&rmask);
 165       FD_SET (0, &rmask);
 166       FD_SET (s, &rmask);
 167       if (select (s + 1, &rmask, 0, 0, 0) < 0)
 168         perror_1 ("select");
 169       if (FD_ISSET (s, &rmask)) /* client sends list of filenames */
 170         {
 171           fromlen = sizeof (fromunix);
 172           fromunix.sun_family = AF_UNIX;
 173           infd = accept (s, (struct sockaddr *) &fromunix, &fromlen);
 174           if (infd < 0)
 175             {
 176               if (errno == EMFILE || errno == ENFILE)
 177                 fprintf (stderr, "Error: too many clients.\n");
 178               else
 179                 perror_1 ("accept");
 180               continue;
 181             }
 182
 183           if (infd >= openfiles_size)
 184             {
 185               openfiles_size *= 2;
 186               openfiles = (FILE **) realloc (openfiles,
 187                                              openfiles_size * sizeof (FILE *));
 188               if (openfiles == 0)
 189                 abort ();
 190             }
 191
 192           infile = fdopen (infd, "r+"); /* open stream */
 193           if (infile == NULL)
 194             {
 195               fprintf (stderr, "Error: too many clients.\n");
 196               write (infd, "Too many clients.\n", 18);
 197               close (infd);             /* Prevent descriptor leak.. */
 198               continue;
 199             }
 200           str = fgets (string, BUFSIZ, infile);
 201           if (str == NULL)
 202             {
 203               perror_1 ("fgets");
 204               close (infd);             /* Prevent descriptor leak.. */
 205               continue;
 206             }
 207           openfiles[infd] = infile;
 208           printf ("Client: %d %s", infd, string);
 209           /* If what we read did not end in a newline,
 210              it means there is more.  Keep reading from the socket
 211              and outputting to Emacs, until we get the newline.  */
 212           while (string[strlen (string) - 1] != '\n')
 213             {
 214               if (fgets (string, BUFSIZ, infile) == 0)
 215                 break;
 216               printf ("%s", string);
 217             }
 218           fflush (stdout);
 219           fflush (infile);
 220           continue;
 221         }
 222       else if (FD_ISSET (0, &rmask)) /* emacs sends codeword, fd, and string message */
 223         {
 224           /* Read command codeword and fd */
 225           clearerr (stdin);
 226           scanf ("%s %d%*c", code, &infd);
 227           if (ferror (stdin) || feof (stdin))
 228             fatal_error ("server: error reading from standard input\n");
 229
 230           /* Transfer text from Emacs to the client, up to a newline.  */
 231           infile = openfiles[infd];
 232           rewind (infile);
 233           while (1)
 234             {
 235               if (fgets (string, BUFSIZ, stdin) == 0)
 236                 break;
 237               fprintf (infile, "%s", string);
 238               if (string[strlen (string) - 1] == '\n')
 239                 break;
 240             }
 241           fflush (infile);
 242
 243           /* If command is close, close connection to client.  */
 244           if (strncmp (code, "Close:", 6) == 0)
 245             if (infd > 2)
 246               {
 247                 fclose (infile);
 248                 close (infd);
 249               }
 250           continue;
 251         }
 252     }
 253 }
 254
 255 #else  /* This is the SYSV IPC section */
 256
 257 #include <sys/types.h>
 258 #include <sys/signal.h>
 259 #include <sys/ipc.h>
 260 #include <sys/msg.h>
 261 #include <setjmp.h>
 262 #include <errno.h>
 263 #include <sys/utsname.h>
 264
 265 struct utsname system_name;
 266
 267 #ifndef errno
 268 extern int errno;
 269 #endif
 270
 271 jmp_buf msgenv;
 272
 273 SIGTYPE
 274 msgcatch ()
 275 {
 276   longjmp (msgenv, 1);
 277 }
 278
 279
 280 /* "THIS has to be fixed.  Remember, stderr may not exist...-rlk."
 281    Incorrect.  This program runs as an inferior of Emacs.
 282    Its stderr always exists--rms.  */
 283 #include <stdio.h>
 284
 285 main ()
 286 {
 287   int s, infd, fromlen, ioproc;
 288   key_t key;
 289   struct msgbuf * msgp =
 290     (struct msgbuf *) malloc (sizeof *msgp + BUFSIZ);
 291   struct msqid_ds msg_st;
 292   int p;
 293   char *homedir, *getenv ();
 294   char string[BUFSIZ];
 295   FILE *infile;
 296
 297   /*
 298    * Create a message queue using ~/.emacs-server as the path for ftok
 299    */
 300   if ((homedir = getenv ("HOME")) == NULL)
 301     fatal_error ("No home directory\n");
 302
 303   strcpy (string, homedir);
 304 #ifndef HAVE_LONG_FILE_NAMES
 305   /* If file names are short, we can't fit the host name.  */
 306   strcat (string, "/.emacs-server");
 307 #else
 308   strcat (string, "/.emacs-server-");
 309   uname (&system_name);
 310   strcat (string, system_name.nodename);
 311 #endif
 312   creat (string, 0600);
 313   key = ftok (string, 1);       /* unlikely to be anyone else using it */
 314   s = msgget (key, 0600 | IPC_CREAT);
 315   if (s == -1)
 316     {
 317       perror_1 ("msgget");
 318       exit (1);
 319     }
 320
 321   /* Fork so we can close connection even if parent dies */
 322   p = fork ();
 323   if (setjmp (msgenv))
 324     {
 325       msgctl (s, IPC_RMID, 0);
 326       if (p > 0)
 327         kill (p, SIGKILL);
 328       exit (0);
 329     }
 330   signal (SIGTERM, msgcatch);
 331   signal (SIGINT, msgcatch);
 332   signal (SIGHUP, msgcatch);
 333   if (p > 0)
 334     {
 335       /* This is executed in the original process that did the fork above.  */
 336       /* Get pid of Emacs itself.  */
 337       p = getppid ();
 338       setpgrp ();               /* Gnu kills process group on exit */
 339       while (1)
 340         {
 341           /* Is Emacs still alive?  */
 342           if (kill (p, 0) < 0)
 343             {
 344               msgctl (s, IPC_RMID, 0);
 345               exit (0);
 346             }
 347           sleep (10);
 348         }
 349     }
 350
 351   /* This is executed in the child made by forking above.
 352      Call it c1.  Make another process, ioproc.  */
 353
 354   ioproc = fork ();
 355   if (ioproc == 0)
 356     {
 357       /* In process ioproc, wait for text from Emacs,
 358          and send it to the process c1.
 359          This way, c1 only has to wait for one source of input.  */
 360       while (fgets (msgp->mtext, BUFSIZ, stdin))
 361         {
 362           msgp->mtype = 1;
 363           msgsnd (s, msgp, strlen (msgp->mtext) + 1, 0);
 364         }
 365       exit (1);
 366     }
 367
 368   /* In the process c1,
 369      listen for messages from clients and pass them to Emacs.  */
 370   while (1)
 371     {
 372       if ((fromlen = msgrcv (s, msgp, BUFSIZ - 1, 1, 0)) < 0)
 373         {
 374 #ifdef EINTR
 375           if (errno == EINTR)
 376             continue;
 377 #endif
 378           perror_1 ("msgrcv");
 379           exit (1);
 380         }
 381       else
 382         {
 383           msgctl (s, IPC_STAT, &msg_st);
 384
 385           /* Distinguish whether the message came from a client, or from
 386              ioproc.  */
 387           if (msg_st.msg_lspid == ioproc)
 388             {
 389               char code[BUFSIZ];
 390               int inproc;
 391
 392               /* Message from ioproc: tell a client we are done.  */
 393               msgp->mtext[strlen (msgp->mtext)-1] = 0;
 394               sscanf (msgp->mtext, "%s %d", code, &inproc);
 395               msgp->mtype = inproc;
 396               msgsnd (s, msgp, strlen (msgp->mtext) + 1, 0);
 397               continue;
 398             }
 399
 400           /* This is a request from a client: copy to stdout
 401              so that Emacs will get it.  Include msg_lspid
 402              so server.el can tell us where to send the reply.  */
 403           strncpy (string, msgp->mtext, fromlen);
 404           string[fromlen] = 0;  /* make sure */
 405           /* Newline is part of string.. */
 406           printf ("Client: %d %s", msg_st.msg_lspid, string);
 407           fflush (stdout);
 408         }
 409     }
 410 }
 411
 412 #endif /* HAVE_SYSVIPC */
 413
 414 #endif /* HAVE_SOCKETS or HAVE_SYSVIPC */
 415 \f
 416 /* This is like perror but puts `Error: ' at the beginning.  */
 417
 418 perror_1 (string)
 419      char *string;
 420 {
 421   char *copy = (char *) malloc (strlen (string) + 8);
 422   if (copy == 0)
 423     fatal_error ("Virtual memory exhausted");
 424
 425   strcpy (copy, "Error: ");
 426   strcat (copy, string);
 427   perror (copy);
 428 }
 429
 430 fatal_error (string)
 431      char *string;
 432 {
 433   fprintf (stderr, "%s", "Error: ");
 434   fprintf (stderr, string);
 435   exit (1);
 436 }