code.delx.au - gnu-emacs/blob - 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
  24 #include "lisp.h"
  25
  26 #include <unistd.h>
  27
  28 #ifdef ENABLE_CHECKING
  29 #define STATIC_HEAP_SIZE        (28 * 1024 * 1024)
  30 #else
  31 #define STATIC_HEAP_SIZE        (19 * 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 /* The following is needed in gmalloc.c */
  40 void *bss_sbrk_buffer_end = bss_sbrk_buffer + STATIC_HEAP_SIZE;
  41 char *bss_sbrk_ptr;
  42 char *max_bss_sbrk_ptr;
  43 int bss_sbrk_did_unexec;
  44
  45 void *
  46 bss_sbrk (ptrdiff_t request_size)
  47 {
  48   if (!bss_sbrk_ptr)
  49     {
  50       max_bss_sbrk_ptr = bss_sbrk_ptr = bss_sbrk_buffer;
  51 #ifdef CYGWIN
  52       sbrk (BLOCKSIZE);         /* force space for fork to work */
  53 #endif
  54     }
  55
  56   if (!(int) request_size)
  57     {
  58       return (bss_sbrk_ptr);
  59     }
  60   else if (bss_sbrk_ptr + (int) request_size < bss_sbrk_buffer)
  61     {
  62       printf
  63         ("attempt to free too much: avail %d used %d failed request %d\n",
  64          STATIC_HEAP_SIZE, bss_sbrk_ptr - bss_sbrk_buffer,
  65          (int) request_size);
  66       exit (-1);
  67       return 0;
  68     }
  69   else if (bss_sbrk_ptr + (int) request_size >
  70            bss_sbrk_buffer + STATIC_HEAP_SIZE)
  71     {
  72       printf ("static heap exhausted: avail %d used %d failed request %d\n",
  73               STATIC_HEAP_SIZE,
  74               bss_sbrk_ptr - bss_sbrk_buffer, (int) request_size);
  75       exit (-1);
  76       return 0;
  77     }
  78   else if ((int) request_size < 0)
  79     {
  80       bss_sbrk_ptr += (int) request_size;
  81       if (debug_sheap)
  82         printf ("freed size %d\n", request_size);
  83       return bss_sbrk_ptr;
  84     }
  85   else
  86     {
  87       char *ret = bss_sbrk_ptr;
  88       if (debug_sheap)
  89         printf ("allocated 0x%08x size %d\n", ret, request_size);
  90       bss_sbrk_ptr += (int) request_size;
  91       if (bss_sbrk_ptr > max_bss_sbrk_ptr)
  92         max_bss_sbrk_ptr = bss_sbrk_ptr;
  93       return ret;
  94     }
  95 }
  96
  97 void
  98 report_sheap_usage (int die_if_pure_storage_exceeded)
  99 {
 100   char buf[200];
 101   sprintf (buf, "Maximum static heap usage: %d of %d bytes",
 102            max_bss_sbrk_ptr - bss_sbrk_buffer, STATIC_HEAP_SIZE);
 103   /* Don't log messages, cause at this point, we're not allowed to create
 104      buffers.  */
 105   message1_nolog (buf);
 106 }