src/unexaix.c

   1 /*
   2   This file is not used because it occasionally fails to work.  This
   3   happens because the bss address when Emacs is run is not always the
   4   same.  If it happens to be different from what it was
   5   when Emacs was dumped, the dumped data won't work.
   6   No one has been able to prevent the address from varying.
   7
   8   The following comments should be in share-lib/MACHINES if this
   9   dumping is ever made to work:
  10
  11   Note that Emacs can store the pure Lisp data in a shared segment on
  12   this machine, but only if you put this command in one of the boot
  13   scripts
  14
  15       emacs -batch -q
  16
  17   so that it is run as root when the machine is booted.  This command
  18   creates a read-only shared segment owned by root.  Otherwise the
  19   pure data is not shared.  The pure data size is around 100K, which
  20   may not be enough to matter for most users of this machine.
  21 */
  22
  23 /* Dumping and loading data areas, for Emacs under AIX.
  24    (It may also work on other kinds of system V.)
  25    Copyright (C) 1990 Free Software Foundation, Inc.
  26
  27 This file is part of GNU Emacs.
  28
  29 GNU Emacs is free software; you can redistribute it and/or modify
  30 it under the terms of the GNU General Public License as published by
  31 the Free Software Foundation; either version 1, or (at your option)
  32 any later version.
  33
  34 GNU Emacs is distributed in the hope that it will be useful,
  35 but WITHOUT ANY WARRANTY; without even the implied warranty of
  36 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  37 GNU General Public License for more details.
  38
  39 You should have received a copy of the GNU General Public License
  40 along with GNU Emacs; see the file COPYING.  If not, write to
  41 the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */
  42
  43 /* This is based on a public domain program written by IBM.  */
  44
  45 /*************** SYSTEM DEFINES *********************************/
  46
  47 #include "config.h"
  48 #include "paths.h"
  49 #include <sys/types.h>
  50 #include <sys/files.h>
  51 #include <fcntl.h>
  52 #include <sys/mode.h>
  53 #include <sys/ipc.h>
  54 #include <sys/shm.h>
  55 #include <malloc.h>
  56 #include <stdio.h>                              /* MWW */
  57 #include "lisp.h"
  58
  59 /*************** LOCAL DEFINES **********************************/
  60
  61 struct data_header              /* saved data header            */
  62 {
  63   char *start;                  /* dump _data addr              */
  64   char *end;                    /* dump _end addr               */
  65   char *sbrk1;                  /* dump original sbrk addr      */
  66   char *sbrk2;                  /* dump final sbrk addr */
  67   int puresize;                 /* size of pure data dumped  */
  68 };
  69
  70 #define EMACSSHMKEY "EMACSSHMKEY"
  71 #define EMACS_DATA_FILE "EMACS-DATA"
  72 #define NEW_SHMGET_FLAGS (IPC_CREAT | S_IWUSR | S_IRUSR \
  73       | S_IWGRP | S_IRGRP | S_IWOTH | S_IROTH)
  74 #define OLD_SHMAT_FLAGS SHM_RDONLY
  75 #define OLD_SHMGET_FLAGS (S_IRUSR | S_IRGRP | S_IROTH)
  76 #define OLD_OPEN_FLAGS O_RDONLY
  77 #define NEW_OPEN_FLAGS (O_RDWR | O_CREAT | O_TRUNC)
  78
  79 /*************** EXTERNAL / GLOBAL DATA AREA ********************/
  80
  81 extern char _data;              /* start of data addr           */
  82 extern char _end;               /* end of all data + 1 addr     */
  83 static char *original_sbrk;     /* sbrk when dump first run     */
  84
  85 void
  86 map_in_data (use_dumped_data)
  87      int use_dumped_data;
  88 {
  89   int bufsize;                  /* malloc buffer size           */
  90   struct data_header dh;        /* saved data header            */
  91   int fd;                       /* saved data file descriptor   */
  92   char *finaladdr;              /* last addr in bucket          */
  93   char *ipckey = getenv (EMACSSHMKEY); /* env ipc key string    */
  94   int length;                   /* dumped data lengths          */
  95   char *newaddr;                /* new malloc buffer addr       */
  96   int numblks;                  /* number of remaining mallocs  */
  97   int shmid;                    /* shared memory id             */
  98   key_t shmkey;                 /* shared memory key            */
  99   /* Note that using malloc here may not be safe.  */
 100   char name[sizeof (PATH_EXEC) + sizeof (EMACS_DATA_FILE) + 2];
 101
 102   /* Consume remaining malloc space without increasing          */
 103   /* the end of data space                                      */
 104   original_sbrk = sbrk (0);
 105   for (bufsize = 16; bufsize < getpagesize (); bufsize *= 2)
 106     {
 107       while ((newaddr = (char *)malloc (bufsize - 8)) < original_sbrk)
 108         ;
 109       for (numblks = (getpagesize () / bufsize) - 1; numblks > 0; numblks--)
 110         malloc (bufsize - 8);
 111       finaladdr = sbrk (0);
 112     }
 113   original_sbrk = sbrk (0);
 114
 115   /* If we don't want the dumped data, get an unshared segment.  */
 116   if (!use_dumped_data)
 117     {
 118       shmid = shmget (IPC_PRIVATE, PURESIZE, NEW_SHMGET_FLAGS);
 119       if (shmid == -1
 120           || shmat (shmid, (char *)PURE_SEG_BITS, 0) == -1)
 121         {
 122           fprintf (stderr, "emacs: failure obtaining new unshared memory segment.\n");
 123           exit (1);
 124         }
 125       return;
 126     }
 127
 128   /* Compute the file name with the dumped data.  */
 129   strcpy (name, PATH_EXEC);
 130   strcat (name, "/");
 131   strcat (name, EMACS_DATA_FILE);
 132
 133   /* Open the file and make sure the addresses have not changed.  */
 134   fd = open (name, OLD_OPEN_FLAGS, 0);
 135   if (fd < 0)
 136     {
 137       fprintf (stderr, "emacs: failure opening `%s'\n", name);
 138       exit (1);
 139     }
 140   if (read (fd, (char *)&dh, sizeof (dh)) != sizeof (dh)
 141       || dh.start != &_data
 142       || dh.end != &_end
 143       || dh.sbrk1 != original_sbrk
 144       || dh.puresize != PURESIZE)
 145     {
 146       fprintf (stderr, "emacs: header mismatch in `%s'\n", name);
 147       exit (1);
 148     }
 149
 150   /* Load in the unshared contents.  */
 151   if (!(length = dh.end - dh.start)
 152       || read (fd, (char *)&_data, length) != length
 153       || !(length = dh.sbrk2 - dh.sbrk1)
 154       || brk (dh.sbrk2) == -1
 155       || read (fd, dh.sbrk1, length) != length)
 156     {
 157       fprintf (stderr, "emacs: failure loading unshared data.\n");
 158       exit (1);
 159     }
 160
 161   /* Determine ipc key from environment or default              */
 162   if (ipckey && *ipckey)
 163     shmkey = atoi (ipckey);
 164   else
 165     shmkey = SHMKEY;
 166
 167   /* Attach to "pure data" shared memory segment                */
 168   if ((shmid = shmget (shmkey, 0, 0)) == -1
 169       || (newaddr = shmat (shmid, (char *)PURE_SEG_BITS, OLD_SHMAT_FLAGS)) == -1)
 170     {
 171       /* We were unable to open an existing segment.  Make a new one.  */
 172       struct shmid_ds buf;
 173
 174       /* First get rid of the one we tried to get.  */
 175       shmdt ((char *)PURE_SEG_BITS);
 176       shmctl (shmid, IPC_RMID, 0);
 177
 178       /* If we could not write the data file,
 179          don't make a shared segment that we could write.
 180          Make an unshared segment instead.  */
 181       if (access (name, W_OK) == 0)
 182         {
 183           shmid = shmget (IPC_PRIVATE, PURESIZE, NEW_SHMGET_FLAGS);
 184           if (shmid == -1
 185               || shmat (shmid, (char *)PURE_SEG_BITS, 0) == -1)
 186             {
 187               fprintf (stderr, "emacs: failure obtaining new unshared memory segment.\n");
 188               exit (1);
 189             }
 190
 191           /* Load the proper data into it.  */
 192           if (read (fd, PURE_SEG_BITS, PURESIZE) != PURESIZE)
 193             {
 194               fprintf (stderr, "emacs: failure loading shared memory data.\n");
 195               shmdt ((char *)PURE_SEG_BITS);
 196               shmctl (shmid, IPC_RMID, 0);
 197               exit (1);
 198             }
 199
 200           close (fd);
 201           return;
 202         }
 203
 204       /* Allocate the new shared segment and arrange to write it.  */
 205       if ((shmid = shmget (shmkey, PURESIZE, NEW_SHMGET_FLAGS)) == -1
 206           || shmat (shmid, (char *)PURE_SEG_BITS, 0) == -1)
 207         {
 208           fprintf (stderr, "emacs: failure obtaining new shared memory segment.\n");
 209           shmdt ((char *)PURE_SEG_BITS);
 210           shmctl (shmid, IPC_RMID, 0);
 211           exit (1);
 212         }
 213
 214       /* Load the proper data into it.  */
 215       if (read (fd, PURE_SEG_BITS, PURESIZE) != PURESIZE)
 216         {
 217           fprintf (stderr, "emacs: failure loading shared memory data.\n");
 218           shmdt ((char *)PURE_SEG_BITS);
 219           shmctl (shmid, IPC_RMID, 0);
 220           exit (1);
 221         }
 222
 223       /* Detach from the segment and bring it back readonly.  */
 224       shmdt ((char *)PURE_SEG_BITS);
 225
 226       shmctl (shmid, IPC_STAT, &buf);
 227       buf.shm_perm.mode = OLD_SHMGET_FLAGS;
 228       shmctl (shmid, IPC_SET, &buf);
 229
 230       newaddr = shmat (shmid, (char *)PURE_SEG_BITS, OLD_SHMAT_FLAGS);
 231       if (newaddr == -1)
 232         {
 233           fprintf (stderr, "emacs: failure reattaching shared memory segment.\n");
 234           shmctl (shmid, IPC_RMID, 0);
 235           exit (1);
 236         }
 237     }
 238
 239   close (fd);
 240 }
 241
 242 /* Dump the appropriate parts of memory into a file named NEW
 243    from which the shared segment can be initialized.  */
 244
 245 void
 246 map_out_data (new)
 247      char *new;
 248 {
 249   struct data_header dh;        /* saved data header                    */
 250   int fd;                       /* saved data file descriptor           */
 251   int length;                   /* dumped data length; */
 252
 253
 254   /* Create "saved data" file header */
 255   dh.start = &_data;
 256   dh.end = &_end;
 257   dh.sbrk1 = original_sbrk;
 258   dh.sbrk2 = sbrk (0);
 259   dh.puresize = PURESIZE;
 260
 261   /* Create new "saved data" dump file                          */
 262   unlink (new);
 263   fd = open (new, NEW_OPEN_FLAGS, 0666);
 264   if (fd < 0)
 265     report_file_error ("Opening dump file", Fcons (build_string (new), Qnil));
 266
 267   /* Write saved header and data                                */
 268   length = sizeof (dh);
 269   if (write (fd, (char *)&dh, length) != length)
 270     report_file_error ("Writing dump file header",
 271                        Fcons (build_string (new), Qnil));
 272   length = dh.end - dh.start;
 273   if (write (fd, dh.start, length) != length)
 274     report_file_error ("Writing low core in dump file",
 275                        Fcons (build_string (new), Qnil));
 276   length = dh.sbrk2 - dh.sbrk1;
 277   if (write (fd, dh.sbrk1, length) != length)
 278     report_file_error ("Writing heap in dump file",
 279                        Fcons (build_string (new), Qnil));
 280   length = PURESIZE;
 281   if (write (fd, PURE_SEG_BITS, length) != length)
 282     report_file_error ("Writing pure data in dump file",
 283                        Fcons (build_string (new), Qnil));
 284   close (fd);
 285 }