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) 2004-2015 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 #include <unistd.h>
  25 #include <stdlib.h>             /* for exit */
  26
  27 #ifdef ENABLE_CHECKING
  28 #define STATIC_HEAP_SIZE        (28 * 1024 * 1024)
  29 #else
  30 #define STATIC_HEAP_SIZE        (19 * 1024 * 1024)
  31 #endif
  32
  33 int debug_sheap = 0;
  34
  35 #define BLOCKSIZE 4096
  36
  37 char bss_sbrk_buffer[STATIC_HEAP_SIZE];
  38 /* The following is needed in gmalloc.c */
  39 void *bss_sbrk_buffer_end = bss_sbrk_buffer + STATIC_HEAP_SIZE;
  40 char *bss_sbrk_ptr;
  41 char *max_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       max_bss_sbrk_ptr = 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       if (bss_sbrk_ptr > max_bss_sbrk_ptr)
  91         max_bss_sbrk_ptr = bss_sbrk_ptr;
  92       return ret;
  93     }
  94 }
  95
  96 void
  97 report_sheap_usage (int die_if_pure_storage_exceeded)
  98 {
  99   char buf[200];
 100   sprintf (buf, "Maximum static heap usage: %d of %d bytes",
 101            max_bss_sbrk_ptr - bss_sbrk_buffer, STATIC_HEAP_SIZE);
 102   /* Don't log messages, cause at this point, we're not allowed to create
 103      buffers.  */
 104   message1_nolog (buf);
 105 }