src/w32heap.c

   1 /* Heap management routines for GNU Emacs on the Microsoft W32 API.
   2    Copyright (C) 1994, 2001, 2002, 2003, 2004, 2005, 2006, 2007,
   3                  2008, 2009, 2010, 2011  Free Software Foundation, Inc.
   4
   5 This file is part of GNU Emacs.
   6
   7 GNU Emacs is free software: you can redistribute it and/or modify
   8 it under the terms of the GNU General Public License as published by
   9 the Free Software Foundation, either version 3 of the License, or
  10 (at your option) any later version.
  11
  12 GNU Emacs is distributed in the hope that it will be useful,
  13 but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 GNU General Public License for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
  19
  20 /*
  21    Geoff Voelker (voelker@cs.washington.edu)                         7-29-94
  22 */
  23
  24 #include <config.h>
  25 #include <stdio.h>
  26 #include <setjmp.h>
  27
  28 #include "w32heap.h"
  29 #include "lisp.h"  /* for VALMASK */
  30
  31 #define RVA_TO_PTR(rva) ((unsigned char *)((DWORD)(rva) + (DWORD)GetModuleHandle (NULL)))
  32
  33 /* This gives us the page size and the size of the allocation unit on NT.  */
  34 SYSTEM_INFO sysinfo_cache;
  35
  36 /* This gives us version, build, and platform identification.  */
  37 OSVERSIONINFO osinfo_cache;
  38
  39 unsigned long syspage_mask = 0;
  40
  41 /* The major and minor versions of NT.  */
  42 int w32_major_version;
  43 int w32_minor_version;
  44 int w32_build_number;
  45
  46 /* Distinguish between Windows NT and Windows 95.  */
  47 int os_subtype;
  48
  49 /* Cache information describing the NT system for later use.  */
  50 void
  51 cache_system_info (void)
  52 {
  53   union
  54     {
  55       struct info
  56         {
  57           char  major;
  58           char  minor;
  59           short platform;
  60         } info;
  61       DWORD data;
  62     } version;
  63
  64   /* Cache the version of the operating system.  */
  65   version.data = GetVersion ();
  66   w32_major_version = version.info.major;
  67   w32_minor_version = version.info.minor;
  68
  69   if (version.info.platform & 0x8000)
  70     os_subtype = OS_WIN95;
  71   else
  72     os_subtype = OS_NT;
  73
  74   /* Cache page size, allocation unit, processor type, etc.  */
  75   GetSystemInfo (&sysinfo_cache);
  76   syspage_mask = sysinfo_cache.dwPageSize - 1;
  77
  78   /* Cache os info.  */
  79   osinfo_cache.dwOSVersionInfoSize = sizeof (OSVERSIONINFO);
  80   GetVersionEx (&osinfo_cache);
  81
  82   w32_build_number = osinfo_cache.dwBuildNumber;
  83   if (os_subtype == OS_WIN95)
  84     w32_build_number &= 0xffff;
  85 }
  86
  87 /* Emulate getpagesize.  */
  88 int
  89 getpagesize (void)
  90 {
  91   return sysinfo_cache.dwPageSize;
  92 }
  93
  94 /* Info for managing our preload heap, which is essentially a fixed size
  95    data area in the executable.  */
  96 PIMAGE_SECTION_HEADER preload_heap_section;
  97
  98 /* Info for keeping track of our heap.  */
  99 unsigned char *data_region_base = NULL;
 100 unsigned char *data_region_end = NULL;
 101 unsigned char *real_data_region_end = NULL;
 102 unsigned long  reserved_heap_size = 0;
 103
 104 /* The start of the data segment.  */
 105 unsigned char *
 106 get_data_start (void)
 107 {
 108   return data_region_base;
 109 }
 110
 111 /* The end of the data segment.  */
 112 unsigned char *
 113 get_data_end (void)
 114 {
 115   return data_region_end;
 116 }
 117
 118 static char *
 119 allocate_heap (void)
 120 {
 121   /* Try to get as much as possible of the address range from the end of
 122      the preload heap section up to the usable address limit.  Since GNU
 123      malloc can handle gaps in the memory it gets from sbrk, we can
 124      simply set the sbrk pointer to the base of the new heap region.  */
 125   unsigned long base =
 126     ROUND_UP ((RVA_TO_PTR (preload_heap_section->VirtualAddress)
 127                + preload_heap_section->Misc.VirtualSize),
 128               get_allocation_unit ());
 129   unsigned long end  = 1 << VALBITS; /* 256MB */
 130   void *ptr = NULL;
 131
 132   while (!ptr && (base < end))
 133     {
 134       reserved_heap_size = end - base;
 135       ptr = VirtualAlloc ((void *) base,
 136                           get_reserved_heap_size (),
 137                           MEM_RESERVE,
 138                           PAGE_NOACCESS);
 139       base += 0x00100000;  /* 1MB increment */
 140     }
 141
 142   return ptr;
 143 }
 144
 145
 146 /* Emulate Unix sbrk.  */
 147 void *
 148 sbrk (unsigned long increment)
 149 {
 150   void *result;
 151   long size = (long) increment;
 152
 153   result = data_region_end;
 154
 155   /* If size is negative, shrink the heap by decommitting pages.  */
 156   if (size < 0)
 157     {
 158       int new_size;
 159       unsigned char *new_data_region_end;
 160
 161       size = -size;
 162
 163       /* Sanity checks.  */
 164       if ((data_region_end - size) < data_region_base)
 165         return NULL;
 166
 167       /* We can only decommit full pages, so allow for
 168          partial deallocation [cga].  */
 169       new_data_region_end = (data_region_end - size);
 170       new_data_region_end = (unsigned char *)
 171         ((long) (new_data_region_end + syspage_mask) & ~syspage_mask);
 172       new_size = real_data_region_end - new_data_region_end;
 173       real_data_region_end = new_data_region_end;
 174       if (new_size > 0)
 175         {
 176           /* Decommit size bytes from the end of the heap.  */
 177           if (using_dynamic_heap
 178               && !VirtualFree (real_data_region_end, new_size, MEM_DECOMMIT))
 179             return NULL;
 180         }
 181
 182       data_region_end -= size;
 183     }
 184   /* If size is positive, grow the heap by committing reserved pages.  */
 185   else if (size > 0)
 186     {
 187       /* Sanity checks.  */
 188       if ((data_region_end + size) >
 189           (data_region_base + get_reserved_heap_size ()))
 190         return NULL;
 191
 192       /* Commit more of our heap. */
 193       if (using_dynamic_heap
 194           && VirtualAlloc (data_region_end, size, MEM_COMMIT,
 195                            PAGE_READWRITE) == NULL)
 196         return NULL;
 197       data_region_end += size;
 198
 199       /* We really only commit full pages, so record where
 200          the real end of committed memory is [cga].  */
 201       real_data_region_end = (unsigned char *)
 202           ((long) (data_region_end + syspage_mask) & ~syspage_mask);
 203     }
 204
 205   return result;
 206 }
 207
 208 /* Initialize the internal heap variables used by sbrk.  When running in
 209    preload phase (ie. in the undumped executable), we rely entirely on a
 210    fixed size heap section included in the .exe itself; this is
 211    preserved during dumping, and truncated to the size actually used.
 212
 213    When running in the dumped executable, we reserve as much as possible
 214    of the address range that is addressable by Lisp object pointers, to
 215    supplement what is left of the preload heap.  Although we cannot rely
 216    on the dynamically allocated arena being contiguous with the static
 217    heap area, it is not a problem because sbrk can pretend that the gap
 218    was allocated by something else; GNU malloc detects when there is a
 219    jump in the sbrk values, and starts a new heap block.  */
 220 void
 221 init_heap (void)
 222 {
 223   PIMAGE_DOS_HEADER dos_header;
 224   PIMAGE_NT_HEADERS nt_header;
 225
 226   dos_header = (PIMAGE_DOS_HEADER) RVA_TO_PTR (0);
 227   nt_header = (PIMAGE_NT_HEADERS) (((unsigned long) dos_header) +
 228                                    dos_header->e_lfanew);
 229   preload_heap_section = find_section ("EMHEAP", nt_header);
 230
 231   if (using_dynamic_heap)
 232     {
 233       data_region_base = allocate_heap ();
 234       if (!data_region_base)
 235         {
 236           printf ("Error: Could not reserve dynamic heap area.\n");
 237           exit (1);
 238         }
 239
 240 #if !defined (USE_LISP_UNION_TYPE) && !defined (USE_LSB_TAG)
 241       /* Ensure that the addresses don't use the upper tag bits since
 242          the Lisp type goes there.  */
 243       if (((unsigned long) data_region_base & ~VALMASK) != 0)
 244         {
 245           printf ("Error: The heap was allocated in upper memory.\n");
 246           exit (1);
 247         }
 248 #endif
 249       data_region_end = data_region_base;
 250       real_data_region_end = data_region_end;
 251     }
 252   else
 253     {
 254       data_region_base = RVA_TO_PTR (preload_heap_section->VirtualAddress);
 255       data_region_end = data_region_base;
 256       real_data_region_end = data_region_end;
 257       reserved_heap_size = preload_heap_section->Misc.VirtualSize;
 258     }
 259
 260   /* Update system version information to match current system.  */
 261   cache_system_info ();
 262 }
 263
 264 /* Round the heap up to the given alignment.  */
 265 void
 266 round_heap (unsigned long align)
 267 {
 268   unsigned long needs_to_be;
 269   unsigned long need_to_alloc;
 270
 271   needs_to_be = (unsigned long) ROUND_UP (get_heap_end (), align);
 272   need_to_alloc = needs_to_be - (unsigned long) get_heap_end ();
 273
 274   if (need_to_alloc)
 275     sbrk (need_to_alloc);
 276 }
 277
 278 #if (_MSC_VER >= 1000 && _MSC_VER < 1300 && !defined (USE_CRT_DLL))
 279
 280 /* MSVC 4.2 invokes these functions from mainCRTStartup to initialize
 281    a heap via HeapCreate.  They are normally defined by the runtime,
 282    but we override them here so that the unnecessary HeapCreate call
 283    is not performed.  */
 284
 285 int __cdecl
 286 _heap_init (void)
 287 {
 288   /* Stepping through the assembly indicates that mainCRTStartup is
 289      expecting a nonzero success return value.  */
 290   return 1;
 291 }
 292
 293 void __cdecl
 294 _heap_term (void)
 295 {
 296   return;
 297 }
 298
 299 #endif
 300