code.delx.au - gnu-emacs/blob - src/w32heap.c

   1 /* Heap management routines for GNU Emacs on the Microsoft W32 API.
   2    Copyright (C) 1994, 2002, 2003, 2004, 2005 Free Software Foundation, Inc.
   3
   4 This file is part of GNU Emacs.
   5
   6 GNU Emacs is free software; you can redistribute it and/or modify
   7 it under the terms of the GNU General Public License as published by
   8 the Free Software Foundation; either version 2, or (at your option)
   9 any later version.
  10
  11 GNU Emacs is distributed in the hope that it will be useful,
  12 but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 GNU General Public License for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GNU Emacs; see the file COPYING.  If not, write to
  18 the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  19 Boston, MA 02110-1301, USA.
  20
  21    Geoff Voelker (voelker@cs.washington.edu)                         7-29-94
  22 */
  23
  24 #ifdef HAVE_CONFIG_H
  25 #include <config.h>
  26 #endif
  27
  28 #include <stdlib.h>
  29 #include <stdio.h>
  30
  31 #include "w32heap.h"
  32 #include "lisp.h"  /* for VALMASK */
  33
  34 #define RVA_TO_PTR(rva) ((unsigned char *)((DWORD)(rva) + (DWORD)GetModuleHandle (NULL)))
  35
  36 /* This gives us the page size and the size of the allocation unit on NT.  */
  37 SYSTEM_INFO sysinfo_cache;
  38
  39 /* This gives us version, build, and platform identification.  */
  40 OSVERSIONINFO osinfo_cache;
  41
  42 unsigned long syspage_mask = 0;
  43
  44 /* These are defined to get Emacs to compile, but are not used.  */
  45 int edata;
  46 int etext;
  47
  48 /* The major and minor versions of NT.  */
  49 int w32_major_version;
  50 int w32_minor_version;
  51 int w32_build_number;
  52
  53 /* Distinguish between Windows NT and Windows 95.  */
  54 int os_subtype;
  55
  56 /* Cache information describing the NT system for later use.  */
  57 void
  58 cache_system_info (void)
  59 {
  60   union
  61     {
  62       struct info
  63         {
  64           char  major;
  65           char  minor;
  66           short platform;
  67         } info;
  68       DWORD data;
  69     } version;
  70
  71   /* Cache the version of the operating system.  */
  72   version.data = GetVersion ();
  73   w32_major_version = version.info.major;
  74   w32_minor_version = version.info.minor;
  75
  76   if (version.info.platform & 0x8000)
  77     os_subtype = OS_WIN95;
  78   else
  79     os_subtype = OS_NT;
  80
  81   /* Cache page size, allocation unit, processor type, etc.  */
  82   GetSystemInfo (&sysinfo_cache);
  83   syspage_mask = sysinfo_cache.dwPageSize - 1;
  84
  85   /* Cache os info.  */
  86   osinfo_cache.dwOSVersionInfoSize = sizeof (OSVERSIONINFO);
  87   GetVersionEx (&osinfo_cache);
  88
  89   w32_build_number = osinfo_cache.dwBuildNumber;
  90   if (os_subtype == OS_WIN95)
  91     w32_build_number &= 0xffff;
  92 }
  93
  94 /* Emulate getpagesize.  */
  95 int
  96 getpagesize (void)
  97 {
  98   return sysinfo_cache.dwPageSize;
  99 }
 100
 101 /* Info for managing our preload heap, which is essentially a fixed size
 102    data area in the executable.  */
 103 PIMAGE_SECTION_HEADER preload_heap_section;
 104
 105 /* Info for keeping track of our heap.  */
 106 unsigned char *data_region_base = NULL;
 107 unsigned char *data_region_end = NULL;
 108 unsigned char *real_data_region_end = NULL;
 109 unsigned long  reserved_heap_size = 0;
 110
 111 /* The start of the data segment.  */
 112 unsigned char *
 113 get_data_start (void)
 114 {
 115   return data_region_base;
 116 }
 117
 118 /* The end of the data segment.  */
 119 unsigned char *
 120 get_data_end (void)
 121 {
 122   return data_region_end;
 123 }
 124
 125 static char *
 126 allocate_heap (void)
 127 {
 128   /* Try to get as much as possible of the address range from the end of
 129      the preload heap section up to the usable address limit.  Since GNU
 130      malloc can handle gaps in the memory it gets from sbrk, we can
 131      simply set the sbrk pointer to the base of the new heap region.  */
 132   unsigned long base =
 133     ROUND_UP ((RVA_TO_PTR (preload_heap_section->VirtualAddress)
 134                + preload_heap_section->Misc.VirtualSize),
 135               get_allocation_unit ());
 136   unsigned long end  = 1 << VALBITS; /* 256MB */
 137   void *ptr = NULL;
 138
 139   while (!ptr && (base < end))
 140     {
 141       reserved_heap_size = end - base;
 142       ptr = VirtualAlloc ((void *) base,
 143                           get_reserved_heap_size (),
 144                           MEM_RESERVE,
 145                           PAGE_NOACCESS);
 146       base += 0x00100000;  /* 1MB increment */
 147     }
 148
 149   return ptr;
 150 }
 151
 152
 153 /* Emulate Unix sbrk.  */
 154 void *
 155 sbrk (unsigned long increment)
 156 {
 157   void *result;
 158   long size = (long) increment;
 159
 160   result = data_region_end;
 161
 162   /* If size is negative, shrink the heap by decommitting pages.  */
 163   if (size < 0)
 164     {
 165       int new_size;
 166       unsigned char *new_data_region_end;
 167
 168       size = -size;
 169
 170       /* Sanity checks.  */
 171       if ((data_region_end - size) < data_region_base)
 172         return NULL;
 173
 174       /* We can only decommit full pages, so allow for
 175          partial deallocation [cga].  */
 176       new_data_region_end = (data_region_end - size);
 177       new_data_region_end = (unsigned char *)
 178         ((long) (new_data_region_end + syspage_mask) & ~syspage_mask);
 179       new_size = real_data_region_end - new_data_region_end;
 180       real_data_region_end = new_data_region_end;
 181       if (new_size > 0)
 182         {
 183           /* Decommit size bytes from the end of the heap.  */
 184           if (using_dynamic_heap
 185               && !VirtualFree (real_data_region_end, new_size, MEM_DECOMMIT))
 186             return NULL;
 187         }
 188
 189       data_region_end -= size;
 190     }
 191   /* If size is positive, grow the heap by committing reserved pages.  */
 192   else if (size > 0)
 193     {
 194       /* Sanity checks.  */
 195       if ((data_region_end + size) >
 196           (data_region_base + get_reserved_heap_size ()))
 197         return NULL;
 198
 199       /* Commit more of our heap. */
 200       if (using_dynamic_heap
 201           && VirtualAlloc (data_region_end, size, MEM_COMMIT,
 202                            PAGE_READWRITE) == NULL)
 203         return NULL;
 204       data_region_end += size;
 205
 206       /* We really only commit full pages, so record where
 207          the real end of committed memory is [cga].  */
 208       real_data_region_end = (unsigned char *)
 209           ((long) (data_region_end + syspage_mask) & ~syspage_mask);
 210     }
 211
 212   return result;
 213 }
 214
 215 /* Initialize the internal heap variables used by sbrk.  When running in
 216    preload phase (ie. in the undumped executable), we rely entirely on a
 217    fixed size heap section included in the .exe itself; this is
 218    preserved during dumping, and truncated to the size actually used.
 219
 220    When running in the dumped executable, we reserve as much as possible
 221    of the address range that is addressable by Lisp object pointers, to
 222    supplement what is left of the preload heap.  Although we cannot rely
 223    on the dynamically allocated arena being contiguous with the static
 224    heap area, it is not a problem because sbrk can pretend that the gap
 225    was allocated by something else; GNU malloc detects when there is a
 226    jump in the sbrk values, and starts a new heap block.  */
 227 void
 228 init_heap ()
 229 {
 230   PIMAGE_DOS_HEADER dos_header;
 231   PIMAGE_NT_HEADERS nt_header;
 232
 233   dos_header = (PIMAGE_DOS_HEADER) RVA_TO_PTR (0);
 234   nt_header = (PIMAGE_NT_HEADERS) (((unsigned long) dos_header) +
 235                                    dos_header->e_lfanew);
 236   preload_heap_section = find_section ("EMHEAP", nt_header);
 237
 238   if (using_dynamic_heap)
 239     {
 240       data_region_base = allocate_heap ();
 241       if (!data_region_base)
 242         {
 243           printf ("Error: Could not reserve dynamic heap area.\n");
 244           exit (1);
 245         }
 246
 247 #if defined (NO_UNION_TYPE) && !defined (USE_LSB_TAG)
 248       /* Ensure that the addresses don't use the upper tag bits since
 249          the Lisp type goes there.  */
 250       if (((unsigned long) data_region_base & ~VALMASK) != 0)
 251         {
 252           printf ("Error: The heap was allocated in upper memory.\n");
 253           exit (1);
 254         }
 255 #endif
 256       data_region_end = data_region_base;
 257       real_data_region_end = data_region_end;
 258     }
 259   else
 260     {
 261       data_region_base = RVA_TO_PTR (preload_heap_section->VirtualAddress);
 262       data_region_end = data_region_base;
 263       real_data_region_end = data_region_end;
 264       reserved_heap_size = preload_heap_section->Misc.VirtualSize;
 265     }
 266
 267   /* Update system version information to match current system.  */
 268   cache_system_info ();
 269 }
 270
 271 /* Round the heap up to the given alignment.  */
 272 void
 273 round_heap (unsigned long align)
 274 {
 275   unsigned long needs_to_be;
 276   unsigned long need_to_alloc;
 277
 278   needs_to_be = (unsigned long) ROUND_UP (get_heap_end (), align);
 279   need_to_alloc = needs_to_be - (unsigned long) get_heap_end ();
 280
 281   if (need_to_alloc)
 282     sbrk (need_to_alloc);
 283 }
 284
 285 #if (_MSC_VER >= 1000 && _MSC_VER < 1300 && !defined(USE_CRT_DLL))
 286
 287 /* MSVC 4.2 invokes these functions from mainCRTStartup to initialize
 288    a heap via HeapCreate.  They are normally defined by the runtime,
 289    but we override them here so that the unnecessary HeapCreate call
 290    is not performed.  */
 291
 292 int __cdecl
 293 _heap_init (void)
 294 {
 295   /* Stepping through the assembly indicates that mainCRTStartup is
 296      expecting a nonzero success return value.  */
 297   return 1;
 298 }
 299
 300 void __cdecl
 301 _heap_term (void)
 302 {
 303   return;
 304 }
 305
 306 #endif
 307
 308 /* arch-tag: 9a6a9860-040d-422d-8905-450dd535cd9c
 309    (do not change this comment) */