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, 2009 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 of the License, or
  11 (at your option) 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.  If not, see <http://www.gnu.org/licenses/>.  */
  20
  21 #include <config.h>
  22 #include <stdio.h>
  23 #include "lisp.h"
  24
  25 #include <unistd.h>
  26
  27 #define STATIC_HEAP_SIZE        (12 * 1024 * 1024)
  28
  29 int debug_sheap = 0;
  30
  31 #define BLOCKSIZE 4096
  32
  33 char bss_sbrk_buffer[STATIC_HEAP_SIZE];
  34 char *bss_sbrk_ptr;
  35 int bss_sbrk_did_unexec;
  36
  37 void *
  38 bss_sbrk (ptrdiff_t request_size)
  39 {
  40   if (!bss_sbrk_ptr)
  41     {
  42       bss_sbrk_ptr = bss_sbrk_buffer;
  43 #ifdef CYGWIN
  44       sbrk (BLOCKSIZE);         /* force space for fork to work */
  45 #endif
  46     }
  47
  48   if (!(int) request_size)
  49     {
  50       return (bss_sbrk_ptr);
  51     }
  52   else if (bss_sbrk_ptr + (int) request_size < bss_sbrk_buffer)
  53     {
  54       printf
  55         ("attempt to free too much: avail %d used %d failed request %d\n",
  56          STATIC_HEAP_SIZE, bss_sbrk_ptr - bss_sbrk_buffer,
  57          (int) request_size);
  58       exit (-1);
  59       return 0;
  60     }
  61   else if (bss_sbrk_ptr + (int) request_size >
  62            bss_sbrk_buffer + STATIC_HEAP_SIZE)
  63     {
  64       printf ("static heap exhausted: avail %d used %d failed request %d\n",
  65               STATIC_HEAP_SIZE,
  66               bss_sbrk_ptr - bss_sbrk_buffer, (int) request_size);
  67       exit (-1);
  68       return 0;
  69     }
  70   else if ((int) request_size < 0)
  71     {
  72       bss_sbrk_ptr += (int) request_size;
  73       if (debug_sheap)
  74         printf ("freed size %d\n", request_size);
  75       return bss_sbrk_ptr;
  76     }
  77   else
  78     {
  79       char *ret = bss_sbrk_ptr;
  80       if (debug_sheap)
  81         printf ("allocated 0x%08x size %d\n", ret, request_size);
  82       bss_sbrk_ptr += (int) request_size;
  83       return ret;
  84     }
  85 }
  86
  87 void
  88 report_sheap_usage (int die_if_pure_storage_exceeded)
  89 {
  90   char buf[200];
  91   sprintf (buf, "Static heap usage: %d of %d bytes",
  92            bss_sbrk_ptr - bss_sbrk_buffer, STATIC_HEAP_SIZE);
  93   message ("%s", buf);
  94 }
  95
  96 /* arch-tag: 1bc386e8-71c2-4da4-b8b5-c1674a9cf926
  97    (do not change this comment) */