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