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, 2007, 2008 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 3, 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 #define STATIC_HEAP_SIZE        (12 * 1024 * 1024)
  30
  31 int debug_sheap = 0;
  32
  33 #define BLOCKSIZE 4096
  34
  35 char bss_sbrk_buffer[STATIC_HEAP_SIZE];
  36 char *bss_sbrk_ptr;
  37 int bss_sbrk_did_unexec;
  38
  39 void *
  40 bss_sbrk (ptrdiff_t request_size)
  41 {
  42   if (!bss_sbrk_ptr)
  43     {
  44       bss_sbrk_ptr = bss_sbrk_buffer;
  45 #ifdef CYGWIN
  46       sbrk (BLOCKSIZE);         /* force space for fork to work */
  47 #endif
  48     }
  49
  50   if (!(int) request_size)
  51     {
  52       return (bss_sbrk_ptr);
  53     }
  54   else if (bss_sbrk_ptr + (int) request_size < bss_sbrk_buffer)
  55     {
  56       printf
  57         ("attempt to free too much: avail %d used %d failed request %d\n",
  58          STATIC_HEAP_SIZE, bss_sbrk_ptr - bss_sbrk_buffer,
  59          (int) request_size);
  60       exit (-1);
  61       return 0;
  62     }
  63   else if (bss_sbrk_ptr + (int) request_size >
  64            bss_sbrk_buffer + STATIC_HEAP_SIZE)
  65     {
  66       printf ("static heap exhausted: avail %d used %d failed request %d\n",
  67               STATIC_HEAP_SIZE,
  68               bss_sbrk_ptr - bss_sbrk_buffer, (int) request_size);
  69       exit (-1);
  70       return 0;
  71     }
  72   else if ((int) request_size < 0)
  73     {
  74       bss_sbrk_ptr += (int) request_size;
  75       if (debug_sheap)
  76         printf ("freed size %d\n", request_size);
  77       return bss_sbrk_ptr;
  78     }
  79   else
  80     {
  81       char *ret = bss_sbrk_ptr;
  82       if (debug_sheap)
  83         printf ("allocated 0x%08x size %d\n", ret, request_size);
  84       bss_sbrk_ptr += (int) request_size;
  85       return ret;
  86     }
  87 }
  88
  89 void
  90 report_sheap_usage (int die_if_pure_storage_exceeded)
  91 {
  92   char buf[200];
  93   sprintf (buf, "Static heap usage: %d of %d bytes",
  94            bss_sbrk_ptr - bss_sbrk_buffer, STATIC_HEAP_SIZE);
  95   message ("%s", buf);
  96 }
  97
  98 /* arch-tag: 1bc386e8-71c2-4da4-b8b5-c1674a9cf926
  99    (do not change this comment) */