src/sheap.c

   1 /* simulate `sbrk' with an array in .bss, for `unexec' support for Cygwin;
   2    complete rewrite of xemacs Cygwin `unexec' code
   3
   4    Copyright (C) 2004, 2005, 2006 Free Software Foundation, Inc.
   5
   6 This file is part of GNU Emacs.
   7
   8 GNU Emacs is free software; you can redistribute it and/or modify
   9 it under the terms of the GNU General Public License as published by
  10 the Free Software Foundation; either version 2, or (at your option)
  11 any later version.
  12
  13 GNU Emacs is distributed in the hope that it will be useful,
  14 but WITHOUT ANY WARRANTY; without even the implied warranty of
  15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16 GNU General Public License for more details.
  17
  18 You should have received a copy of the GNU General Public License
  19 along with GNU Emacs; see the file COPYING.  If not, write to
  20 the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  21 Boston, MA 02110-1301, USA.  */
  22
  23 #include <config.h>
  24 #include <stdio.h>
  25 #include "lisp.h"
  26
  27 #include <unistd.h>
  28
  29 #ifdef HAVE_X_WINDOWS
  30 #define STATIC_HEAP_SIZE        (8 * 1024 * 1024)
  31 #else
  32 #define STATIC_HEAP_SIZE        (8 * 1024 * 1024)
  33 #endif
  34
  35 int debug_sheap = 0;
  36
  37 #define BLOCKSIZE 4096
  38
  39 char bss_sbrk_buffer[STATIC_HEAP_SIZE];
  40 char *bss_sbrk_ptr;
  41 int bss_sbrk_did_unexec;
  42
  43 void *
  44 bss_sbrk (ptrdiff_t request_size)
  45 {
  46   if (!bss_sbrk_ptr)
  47     {
  48       bss_sbrk_ptr = bss_sbrk_buffer;
  49 #ifdef CYGWIN
  50       sbrk (BLOCKSIZE);         /* force space for fork to work */
  51 #endif
  52     }
  53
  54   if (!(int) request_size)
  55     {
  56       return (bss_sbrk_ptr);
  57     }
  58   else if (bss_sbrk_ptr + (int) request_size < bss_sbrk_buffer)
  59     {
  60       printf
  61         ("attempt to free too much: avail %d used %d failed request %d\n",
  62          STATIC_HEAP_SIZE, bss_sbrk_ptr - bss_sbrk_buffer,
  63          (int) request_size);
  64       exit (-1);
  65       return 0;
  66     }
  67   else if (bss_sbrk_ptr + (int) request_size >
  68            bss_sbrk_buffer + STATIC_HEAP_SIZE)
  69     {
  70       printf ("static heap exhausted: avail %d used %d failed request %d\n",
  71               STATIC_HEAP_SIZE,
  72               bss_sbrk_ptr - bss_sbrk_buffer, (int) request_size);
  73       exit (-1);
  74       return 0;
  75     }
  76   else if ((int) request_size < 0)
  77     {
  78       bss_sbrk_ptr += (int) request_size;
  79       if (debug_sheap)
  80         printf ("freed size %d\n", request_size);
  81       return bss_sbrk_ptr;
  82     }
  83   else
  84     {
  85       char *ret = bss_sbrk_ptr;
  86       if (debug_sheap)
  87         printf ("allocated 0x%08x size %d\n", ret, request_size);
  88       bss_sbrk_ptr += (int) request_size;
  89       return ret;
  90     }
  91 }
  92
  93 void
  94 report_sheap_usage (int die_if_pure_storage_exceeded)
  95 {
  96   char buf[200];
  97   sprintf (buf, "Static heap usage: %d of %d bytes",
  98            bss_sbrk_ptr - bss_sbrk_buffer, STATIC_HEAP_SIZE);
  99   message ("%s", buf);
 100 }
 101
 102 /* arch-tag: 1bc386e8-71c2-4da4-b8b5-c1674a9cf926
 103    (do not change this comment) */