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