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