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) 2004-2013 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
  24 #include "lisp.h"
  25
  26 #include <unistd.h>
  27
  28 #ifdef __x86_64__
  29 #define STATIC_HEAP_SIZE        (18 * 1024 * 1024)
  30 #else
  31 #define STATIC_HEAP_SIZE        (13 * 1024 * 1024)
  32 #endif
  33
  34 int debug_sheap = 0;
  35
  36 #define BLOCKSIZE 4096
  37
  38 char bss_sbrk_buffer[STATIC_HEAP_SIZE];
  39 char *bss_sbrk_ptr;
  40 int bss_sbrk_did_unexec;
  41
  42 void *
  43 bss_sbrk (ptrdiff_t request_size)
  44 {
  45   if (!bss_sbrk_ptr)
  46     {
  47       bss_sbrk_ptr = bss_sbrk_buffer;
  48 #ifdef CYGWIN
  49       sbrk (BLOCKSIZE);         /* force space for fork to work */
  50 #endif
  51     }
  52
  53   if (!(int) request_size)
  54     {
  55       return (bss_sbrk_ptr);
  56     }
  57   else if (bss_sbrk_ptr + (int) request_size < bss_sbrk_buffer)
  58     {
  59       printf
  60         ("attempt to free too much: avail %d used %d failed request %d\n",
  61          STATIC_HEAP_SIZE, bss_sbrk_ptr - bss_sbrk_buffer,
  62          (int) request_size);
  63       exit (-1);
  64       return 0;
  65     }
  66   else if (bss_sbrk_ptr + (int) request_size >
  67            bss_sbrk_buffer + STATIC_HEAP_SIZE)
  68     {
  69       printf ("static heap exhausted: avail %d used %d failed request %d\n",
  70               STATIC_HEAP_SIZE,
  71               bss_sbrk_ptr - bss_sbrk_buffer, (int) request_size);
  72       exit (-1);
  73       return 0;
  74     }
  75   else if ((int) request_size < 0)
  76     {
  77       bss_sbrk_ptr += (int) request_size;
  78       if (debug_sheap)
  79         printf ("freed size %d\n", request_size);
  80       return bss_sbrk_ptr;
  81     }
  82   else
  83     {
  84       char *ret = bss_sbrk_ptr;
  85       if (debug_sheap)
  86         printf ("allocated 0x%08x size %d\n", ret, request_size);
  87       bss_sbrk_ptr += (int) request_size;
  88       return ret;
  89     }
  90 }
  91
  92 void
  93 report_sheap_usage (int die_if_pure_storage_exceeded)
  94 {
  95   char buf[200];
  96   sprintf (buf, "Static heap usage: %d of %d bytes",
  97            bss_sbrk_ptr - bss_sbrk_buffer, STATIC_HEAP_SIZE);
  98   /* Don't log messages, cause at this point, we're not allowed to create
  99      buffers.  */
 100   message1_nolog (buf);
 101 }