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