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 #ifdef HAVE_CONFIG_H
  25 #include <config.h>
  26 #endif
  27
  28 #include <stdlib.h>
  29 #include <stdio.h>
  30 #include <setjmp.h>
  31
  32 #include "w32heap.h"
  33 #include "lisp.h"  /* for VALMASK */
  34
  35 #define RVA_TO_PTR(rva) ((unsigned char *)((DWORD)(rva) + (DWORD)GetModuleHandle (NULL)))
  36
  37 /* This gives us the page size and the size of the allocation unit on NT.  */
  38 SYSTEM_INFO sysinfo_cache;
  39
  40 /* This gives us version, build, and platform identification.  */
  41 OSVERSIONINFO osinfo_cache;
  42
  43 unsigned long syspage_mask = 0;
  44
  45 /* The major and minor versions of NT.  */
  46 int w32_major_version;
  47 int w32_minor_version;
  48 int w32_build_number;
  49
  50 /* Distinguish between Windows NT and Windows 95.  */
  51 int os_subtype;
  52
  53 /* Cache information describing the NT system for later use.  */
  54 void
  55 cache_system_info (void)
  56 {
  57   union
  58     {
  59       struct info
  60         {
  61           char  major;
  62           char  minor;
  63           short platform;
  64         } info;
  65       DWORD data;
  66     } version;
  67
  68   /* Cache the version of the operating system.  */
  69   version.data = GetVersion ();
  70   w32_major_version = version.info.major;
  71   w32_minor_version = version.info.minor;
  72
  73   if (version.info.platform & 0x8000)
  74     os_subtype = OS_WIN95;
  75   else
  76     os_subtype = OS_NT;
  77
  78   /* Cache page size, allocation unit, processor type, etc.  */
  79   GetSystemInfo (&sysinfo_cache);
  80   syspage_mask = sysinfo_cache.dwPageSize - 1;
  81
  82   /* Cache os info.  */
  83   osinfo_cache.dwOSVersionInfoSize = sizeof (OSVERSIONINFO);
  84   GetVersionEx (&osinfo_cache);
  85
  86   w32_build_number = osinfo_cache.dwBuildNumber;
  87   if (os_subtype == OS_WIN95)
  88     w32_build_number &= 0xffff;
  89 }
  90
  91 /* Emulate getpagesize.  */
  92 int
  93 getpagesize (void)
  94 {
  95   return sysinfo_cache.dwPageSize;
  96 }
  97
  98 /* Info for managing our preload heap, which is essentially a fixed size
  99    data area in the executable.  */
 100 PIMAGE_SECTION_HEADER preload_heap_section;
 101
 102 /* Info for keeping track of our heap.  */
 103 unsigned char *data_region_base = NULL;
 104 unsigned char *data_region_end = NULL;
 105 unsigned char *real_data_region_end = NULL;
 106 unsigned long  reserved_heap_size = 0;
 107
 108 /* The start of the data segment.  */
 109 unsigned char *
 110 get_data_start (void)
 111 {
 112   return data_region_base;
 113 }
 114
 115 /* The end of the data segment.  */
 116 unsigned char *
 117 get_data_end (void)
 118 {
 119   return data_region_end;
 120 }
 121
 122 static char *
 123 allocate_heap (void)
 124 {
 125   /* Try to get as much as possible of the address range from the end of
 126      the preload heap section up to the usable address limit.  Since GNU
 127      malloc can handle gaps in the memory it gets from sbrk, we can
 128      simply set the sbrk pointer to the base of the new heap region.  */
 129   unsigned long base =
 130     ROUND_UP ((RVA_TO_PTR (preload_heap_section->VirtualAddress)
 131                + preload_heap_section->Misc.VirtualSize),
 132               get_allocation_unit ());
 133   unsigned long end  = 1 << VALBITS; /* 256MB */
 134   void *ptr = NULL;
 135
 136   while (!ptr && (base < end))
 137     {
 138       reserved_heap_size = end - base;
 139       ptr = VirtualAlloc ((void *) base,
 140                           get_reserved_heap_size (),
 141                           MEM_RESERVE,
 142                           PAGE_NOACCESS);
 143       base += 0x00100000;  /* 1MB increment */
 144     }
 145
 146   return ptr;
 147 }
 148
 149
 150 /* Emulate Unix sbrk.  */
 151 void *
 152 sbrk (unsigned long increment)
 153 {
 154   void *result;
 155   long size = (long) increment;
 156
 157   result = data_region_end;
 158
 159   /* If size is negative, shrink the heap by decommitting pages.  */
 160   if (size < 0)
 161     {
 162       int new_size;
 163       unsigned char *new_data_region_end;
 164
 165       size = -size;
 166
 167       /* Sanity checks.  */
 168       if ((data_region_end - size) < data_region_base)
 169         return NULL;
 170
 171       /* We can only decommit full pages, so allow for
 172          partial deallocation [cga].  */
 173       new_data_region_end = (data_region_end - size);
 174       new_data_region_end = (unsigned char *)
 175         ((long) (new_data_region_end + syspage_mask) & ~syspage_mask);
 176       new_size = real_data_region_end - new_data_region_end;
 177       real_data_region_end = new_data_region_end;
 178       if (new_size > 0)
 179         {
 180           /* Decommit size bytes from the end of the heap.  */
 181           if (using_dynamic_heap
 182               && !VirtualFree (real_data_region_end, new_size, MEM_DECOMMIT))
 183             return NULL;
 184         }
 185
 186       data_region_end -= size;
 187     }
 188   /* If size is positive, grow the heap by committing reserved pages.  */
 189   else if (size > 0)
 190     {
 191       /* Sanity checks.  */
 192       if ((data_region_end + size) >
 193           (data_region_base + get_reserved_heap_size ()))
 194         return NULL;
 195
 196       /* Commit more of our heap. */
 197       if (using_dynamic_heap
 198           && VirtualAlloc (data_region_end, size, MEM_COMMIT,
 199                            PAGE_READWRITE) == NULL)
 200         return NULL;
 201       data_region_end += size;
 202
 203       /* We really only commit full pages, so record where
 204          the real end of committed memory is [cga].  */
 205       real_data_region_end = (unsigned char *)
 206           ((long) (data_region_end + syspage_mask) & ~syspage_mask);
 207     }
 208
 209   return result;
 210 }
 211
 212 /* Initialize the internal heap variables used by sbrk.  When running in
 213    preload phase (ie. in the undumped executable), we rely entirely on a
 214    fixed size heap section included in the .exe itself; this is
 215    preserved during dumping, and truncated to the size actually used.
 216
 217    When running in the dumped executable, we reserve as much as possible
 218    of the address range that is addressable by Lisp object pointers, to
 219    supplement what is left of the preload heap.  Although we cannot rely
 220    on the dynamically allocated arena being contiguous with the static
 221    heap area, it is not a problem because sbrk can pretend that the gap
 222    was allocated by something else; GNU malloc detects when there is a
 223    jump in the sbrk values, and starts a new heap block.  */
 224 void
 225 init_heap ()
 226 {
 227   PIMAGE_DOS_HEADER dos_header;
 228   PIMAGE_NT_HEADERS nt_header;
 229
 230   dos_header = (PIMAGE_DOS_HEADER) RVA_TO_PTR (0);
 231   nt_header = (PIMAGE_NT_HEADERS) (((unsigned long) dos_header) +
 232                                    dos_header->e_lfanew);
 233   preload_heap_section = find_section ("EMHEAP", nt_header);
 234
 235   if (using_dynamic_heap)
 236     {
 237       data_region_base = allocate_heap ();
 238       if (!data_region_base)
 239         {
 240           printf ("Error: Could not reserve dynamic heap area.\n");
 241           exit (1);
 242         }
 243
 244 #if !defined (USE_LISP_UNION_TYPE) && !defined (USE_LSB_TAG)
 245       /* Ensure that the addresses don't use the upper tag bits since
 246          the Lisp type goes there.  */
 247       if (((unsigned long) data_region_base & ~VALMASK) != 0)
 248         {
 249           printf ("Error: The heap was allocated in upper memory.\n");
 250           exit (1);
 251         }
 252 #endif
 253       data_region_end = data_region_base;
 254       real_data_region_end = data_region_end;
 255     }
 256   else
 257     {
 258       data_region_base = RVA_TO_PTR (preload_heap_section->VirtualAddress);
 259       data_region_end = data_region_base;
 260       real_data_region_end = data_region_end;
 261       reserved_heap_size = preload_heap_section->Misc.VirtualSize;
 262     }
 263
 264   /* Update system version information to match current system.  */
 265   cache_system_info ();
 266 }
 267
 268 /* Round the heap up to the given alignment.  */
 269 void
 270 round_heap (unsigned long align)
 271 {
 272   unsigned long needs_to_be;
 273   unsigned long need_to_alloc;
 274
 275   needs_to_be = (unsigned long) ROUND_UP (get_heap_end (), align);
 276   need_to_alloc = needs_to_be - (unsigned long) get_heap_end ();
 277
 278   if (need_to_alloc)
 279     sbrk (need_to_alloc);
 280 }
 281
 282 #if (_MSC_VER >= 1000 && _MSC_VER < 1300 && !defined (USE_CRT_DLL))
 283
 284 /* MSVC 4.2 invokes these functions from mainCRTStartup to initialize
 285    a heap via HeapCreate.  They are normally defined by the runtime,
 286    but we override them here so that the unnecessary HeapCreate call
 287    is not performed.  */
 288
 289 int __cdecl
 290 _heap_init (void)
 291 {
 292   /* Stepping through the assembly indicates that mainCRTStartup is
 293      expecting a nonzero success return value.  */
 294   return 1;
 295 }
 296
 297 void __cdecl
 298 _heap_term (void)
 299 {
 300   return;
 301 }
 302
 303 #endif
 304
 305 /* arch-tag: 9a6a9860-040d-422d-8905-450dd535cd9c
 306    (do not change this comment) */