Modules/mmapmodule.c

   1 /*
   2  /  Author: Sam Rushing <rushing@nightmare.com>
   3  /  Hacked for Unix by AMK
   4  /  $Id$
   5
   6  / Modified to support mmap with offset - to map a 'window' of a file
   7  /   Author:  Yotam Medini  yotamm@mellanox.co.il
   8  /
   9  / mmapmodule.cpp -- map a view of a file into memory
  10  /
  11  / todo: need permission flags, perhaps a 'chsize' analog
  12  /   not all functions check range yet!!!
  13  /
  14  /
  15  / This version of mmapmodule.c has been changed significantly
  16  / from the original mmapfile.c on which it was based.
  17  / The original version of mmapfile is maintained by Sam at
  18  / ftp://squirl.nightmare.com/pub/python/python-ext.
  19 */
  20
  21 #define PY_SSIZE_T_CLEAN
  22 #include <Python.h>
  23
  24 #ifndef MS_WINDOWS
  25 #define UNIX
  26 #endif
  27
  28 #ifdef MS_WINDOWS
  29 #include <windows.h>
  30 static int
  31 my_getpagesize(void)
  32 {
  33         SYSTEM_INFO si;
  34         GetSystemInfo(&si);
  35         return si.dwPageSize;
  36 }
  37
  38 static int
  39 my_getallocationgranularity (void)
  40 {
  41
  42         SYSTEM_INFO si;
  43         GetSystemInfo(&si);
  44         return si.dwAllocationGranularity;
  45 }
  46
  47 #endif
  48
  49 #ifdef UNIX
  50 #include <sys/mman.h>
  51 #include <sys/stat.h>
  52
  53 #if defined(HAVE_SYSCONF) && defined(_SC_PAGESIZE)
  54 static int
  55 my_getpagesize(void)
  56 {
  57         return sysconf(_SC_PAGESIZE);
  58 }
  59
  60 #define my_getallocationgranularity my_getpagesize
  61 #else
  62 #define my_getpagesize getpagesize
  63 #endif
  64
  65 #endif /* UNIX */
  66
  67 #include <string.h>
  68
  69 #ifdef HAVE_SYS_TYPES_H
  70 #include <sys/types.h>
  71 #endif /* HAVE_SYS_TYPES_H */
  72
  73 /* Prefer MAP_ANONYMOUS since MAP_ANON is deprecated according to man page. */
  74 #if !defined(MAP_ANONYMOUS) && defined(MAP_ANON)
  75 #  define MAP_ANONYMOUS MAP_ANON
  76 #endif
  77
  78 static PyObject *mmap_module_error;
  79
  80 typedef enum
  81 {
  82         ACCESS_DEFAULT,
  83         ACCESS_READ,
  84         ACCESS_WRITE,
  85         ACCESS_COPY
  86 } access_mode;
  87
  88 typedef struct {
  89         PyObject_HEAD
  90         char *  data;
  91         size_t  size;
  92         size_t  pos;    /* relative to offset */
  93         size_t  offset;
  94
  95 #ifdef MS_WINDOWS
  96         HANDLE  map_handle;
  97         HANDLE  file_handle;
  98         char *  tagname;
  99 #endif
 100
 101 #ifdef UNIX
 102         int fd;
 103 #endif
 104
 105         access_mode access;
 106 } mmap_object;
 107
 108
 109 static void
 110 mmap_object_dealloc(mmap_object *m_obj)
 111 {
 112 #ifdef MS_WINDOWS
 113         if (m_obj->data != NULL)
 114                 UnmapViewOfFile (m_obj->data);
 115         if (m_obj->map_handle != INVALID_HANDLE_VALUE)
 116                 CloseHandle (m_obj->map_handle);
 117         if (m_obj->file_handle != INVALID_HANDLE_VALUE)
 118                 CloseHandle (m_obj->file_handle);
 119         if (m_obj->tagname)
 120                 PyMem_Free(m_obj->tagname);
 121 #endif /* MS_WINDOWS */
 122
 123 #ifdef UNIX
 124         if (m_obj->fd >= 0)
 125                 (void) close(m_obj->fd);
 126         if (m_obj->data!=NULL) {
 127                 msync(m_obj->data, m_obj->size, MS_SYNC);
 128                 munmap(m_obj->data, m_obj->size);
 129         }
 130 #endif /* UNIX */
 131
 132         Py_TYPE(m_obj)->tp_free((PyObject*)m_obj);
 133 }
 134
 135 static PyObject *
 136 mmap_close_method(mmap_object *self, PyObject *unused)
 137 {
 138 #ifdef MS_WINDOWS
 139         /* For each resource we maintain, we need to check
 140            the value is valid, and if so, free the resource
 141            and set the member value to an invalid value so
 142            the dealloc does not attempt to resource clearing
 143            again.
 144            TODO - should we check for errors in the close operations???
 145         */
 146         if (self->data != NULL) {
 147                 UnmapViewOfFile(self->data);
 148                 self->data = NULL;
 149         }
 150         if (self->map_handle != INVALID_HANDLE_VALUE) {
 151                 CloseHandle(self->map_handle);
 152                 self->map_handle = INVALID_HANDLE_VALUE;
 153         }
 154         if (self->file_handle != INVALID_HANDLE_VALUE) {
 155                 CloseHandle(self->file_handle);
 156                 self->file_handle = INVALID_HANDLE_VALUE;
 157         }
 158 #endif /* MS_WINDOWS */
 159
 160 #ifdef UNIX
 161         (void) close(self->fd);
 162         self->fd = -1;
 163         if (self->data != NULL) {
 164                 munmap(self->data, self->size);
 165                 self->data = NULL;
 166         }
 167 #endif
 168
 169         Py_INCREF(Py_None);
 170         return Py_None;
 171 }
 172
 173 #ifdef MS_WINDOWS
 174 #define CHECK_VALID(err)                                                \
 175 do {                                                                    \
 176     if (self->map_handle == INVALID_HANDLE_VALUE) {                                             \
 177         PyErr_SetString(PyExc_ValueError, "mmap closed or invalid");    \
 178         return err;                                                     \
 179     }                                                                   \
 180 } while (0)
 181 #endif /* MS_WINDOWS */
 182
 183 #ifdef UNIX
 184 #define CHECK_VALID(err)                                                \
 185 do {                                                                    \
 186     if (self->data == NULL) {                                           \
 187         PyErr_SetString(PyExc_ValueError, "mmap closed or invalid");    \
 188         return err;                                                     \
 189         }                                                               \
 190 } while (0)
 191 #endif /* UNIX */
 192
 193 static PyObject *
 194 mmap_read_byte_method(mmap_object *self,
 195                       PyObject *unused)
 196 {
 197         CHECK_VALID(NULL);
 198         if (self->pos < self->size) {
 199                 char value = self->data[self->pos];
 200                 self->pos += 1;
 201                 return Py_BuildValue("c", value);
 202         } else {
 203                 PyErr_SetString(PyExc_ValueError, "read byte out of range");
 204                 return NULL;
 205         }
 206 }
 207
 208 static PyObject *
 209 mmap_read_line_method(mmap_object *self,
 210                       PyObject *unused)
 211 {
 212         char *start = self->data+self->pos;
 213         char *eof = self->data+self->size;
 214         char *eol;
 215         PyObject *result;
 216
 217         CHECK_VALID(NULL);
 218
 219         eol = memchr(start, '\n', self->size - self->pos);
 220         if (!eol)
 221                 eol = eof;
 222         else
 223                 ++eol;          /* we're interested in the position after the
 224                                    newline. */
 225         result = PyString_FromStringAndSize(start, (eol - start));
 226         self->pos += (eol - start);
 227         return result;
 228 }
 229
 230 static PyObject *
 231 mmap_read_method(mmap_object *self,
 232                  PyObject *args)
 233 {
 234         Py_ssize_t num_bytes;
 235         PyObject *result;
 236
 237         CHECK_VALID(NULL);
 238         if (!PyArg_ParseTuple(args, "n:read", &num_bytes))
 239                 return(NULL);
 240
 241         /* silently 'adjust' out-of-range requests */
 242         if ((self->pos + num_bytes) > self->size) {
 243                 num_bytes -= (self->pos+num_bytes) - self->size;
 244         }
 245         result = Py_BuildValue("s#", self->data+self->pos, num_bytes);
 246         self->pos += num_bytes;
 247         return result;
 248 }
 249
 250 static PyObject *
 251 mmap_gfind(mmap_object *self,
 252            PyObject *args,
 253            int reverse)
 254 {
 255         Py_ssize_t start = self->pos;
 256         Py_ssize_t end = self->size;
 257         const char *needle;
 258         Py_ssize_t len;
 259
 260         CHECK_VALID(NULL);
 261         if (!PyArg_ParseTuple(args, reverse ? "s#|nn:rfind" : "s#|nn:find",
 262                               &needle, &len, &start, &end)) {
 263                 return NULL;
 264         } else {
 265                 const char *p, *start_p, *end_p;
 266                 int sign = reverse ? -1 : 1;
 267
 268                 if (start < 0)
 269                         start += self->size;
 270                 if (start < 0)
 271                         start = 0;
 272                 else if ((size_t)start > self->size)
 273                         start = self->size;
 274
 275                 if (end < 0)
 276                         end += self->size;
 277                 if (end < 0)
 278                         end = 0;
 279                 else if ((size_t)end > self->size)
 280                         end = self->size;
 281
 282                 start_p = self->data + start;
 283                 end_p = self->data + end;
 284
 285                 for (p = (reverse ? end_p - len : start_p);
 286                      (p >= start_p) && (p + len <= end_p); p += sign) {
 287                         Py_ssize_t i;
 288                         for (i = 0; i < len && needle[i] == p[i]; ++i)
 289                                 /* nothing */;
 290                         if (i == len) {
 291                                 return PyInt_FromSsize_t(p - self->data);
 292                         }
 293                 }
 294                 return PyInt_FromLong(-1);
 295         }
 296 }
 297
 298 static PyObject *
 299 mmap_find_method(mmap_object *self,
 300                  PyObject *args)
 301 {
 302         return mmap_gfind(self, args, 0);
 303 }
 304
 305 static PyObject *
 306 mmap_rfind_method(mmap_object *self,
 307                  PyObject *args)
 308 {
 309         return mmap_gfind(self, args, 1);
 310 }
 311
 312 static int
 313 is_writeable(mmap_object *self)
 314 {
 315         if (self->access != ACCESS_READ)
 316                 return 1;
 317         PyErr_Format(PyExc_TypeError, "mmap can't modify a readonly memory map.");
 318         return 0;
 319 }
 320
 321 static int
 322 is_resizeable(mmap_object *self)
 323 {
 324         if ((self->access == ACCESS_WRITE) || (self->access == ACCESS_DEFAULT))
 325                 return 1;
 326         PyErr_Format(PyExc_TypeError,
 327                      "mmap can't resize a readonly or copy-on-write memory map.");
 328         return 0;
 329 }
 330
 331
 332 static PyObject *
 333 mmap_write_method(mmap_object *self,
 334                   PyObject *args)
 335 {
 336         Py_ssize_t length;
 337         char *data;
 338
 339         CHECK_VALID(NULL);
 340         if (!PyArg_ParseTuple(args, "s#:write", &data, &length))
 341                 return(NULL);
 342
 343         if (!is_writeable(self))
 344                 return NULL;
 345
 346         if ((self->pos + length) > self->size) {
 347                 PyErr_SetString(PyExc_ValueError, "data out of range");
 348                 return NULL;
 349         }
 350         memcpy(self->data+self->pos, data, length);
 351         self->pos = self->pos+length;
 352         Py_INCREF(Py_None);
 353         return Py_None;
 354 }
 355
 356 static PyObject *
 357 mmap_write_byte_method(mmap_object *self,
 358                        PyObject *args)
 359 {
 360         char value;
 361
 362         CHECK_VALID(NULL);
 363         if (!PyArg_ParseTuple(args, "c:write_byte", &value))
 364                 return(NULL);
 365
 366         if (!is_writeable(self))
 367                 return NULL;
 368         *(self->data+self->pos) = value;
 369         self->pos += 1;
 370         Py_INCREF(Py_None);
 371         return Py_None;
 372 }
 373
 374 static PyObject *
 375 mmap_size_method(mmap_object *self,
 376                  PyObject *unused)
 377 {
 378         CHECK_VALID(NULL);
 379
 380 #ifdef MS_WINDOWS
 381         if (self->file_handle != INVALID_HANDLE_VALUE) {
 382                 DWORD low,high;
 383                 PY_LONG_LONG size;
 384                 low = GetFileSize(self->file_handle, &high);
 385                 if (low == INVALID_FILE_SIZE) {
 386                         /* It might be that the function appears to have failed,
 387                            when indeed its size equals INVALID_FILE_SIZE */
 388                         DWORD error = GetLastError();
 389                         if (error != NO_ERROR)
 390                                 return PyErr_SetFromWindowsErr(error);
 391                 }
 392                 if (!high && low < LONG_MAX)
 393                         return PyInt_FromLong((long)low);
 394                 size = (((PY_LONG_LONG)high)<<32) + low;
 395                 return PyLong_FromLongLong(size);
 396         } else {
 397                 return PyInt_FromSsize_t(self->size);
 398         }
 399 #endif /* MS_WINDOWS */
 400
 401 #ifdef UNIX
 402         {
 403                 struct stat buf;
 404                 if (-1 == fstat(self->fd, &buf)) {
 405                         PyErr_SetFromErrno(mmap_module_error);
 406                         return NULL;
 407                 }
 408                 return PyInt_FromSsize_t(buf.st_size);
 409         }
 410 #endif /* UNIX */
 411 }
 412
 413 /* This assumes that you want the entire file mapped,
 414  / and when recreating the map will make the new file
 415  / have the new size
 416  /
 417  / Is this really necessary?  This could easily be done
 418  / from python by just closing and re-opening with the
 419  / new size?
 420  */
 421
 422 static PyObject *
 423 mmap_resize_method(mmap_object *self,
 424                    PyObject *args)
 425 {
 426         Py_ssize_t new_size;
 427         CHECK_VALID(NULL);
 428         if (!PyArg_ParseTuple(args, "n:resize", &new_size) ||
 429             !is_resizeable(self)) {
 430                 return NULL;
 431 #ifdef MS_WINDOWS
 432         } else {
 433                 DWORD dwErrCode = 0;
 434                 DWORD off_hi, off_lo, newSizeLow, newSizeHigh;
 435                 /* First, unmap the file view */
 436                 UnmapViewOfFile(self->data);
 437                 /* Close the mapping object */
 438                 CloseHandle(self->map_handle);
 439                 /* Move to the desired EOF position */
 440 #if SIZEOF_SIZE_T > 4
 441                 newSizeHigh = (DWORD)((self->offset + new_size) >> 32);
 442                 newSizeLow = (DWORD)((self->offset + new_size) & 0xFFFFFFFF);
 443                 off_hi = (DWORD)(self->offset >> 32);
 444                 off_lo = (DWORD)(self->offset & 0xFFFFFFFF);
 445 #else
 446                 newSizeHigh = 0;
 447                 newSizeLow = (DWORD)new_size;
 448                 off_hi = 0;
 449                 off_lo = (DWORD)self->offset;
 450 #endif
 451                 SetFilePointer(self->file_handle,
 452                                newSizeLow, &newSizeHigh, FILE_BEGIN);
 453                 /* Change the size of the file */
 454                 SetEndOfFile(self->file_handle);
 455                 /* Create another mapping object and remap the file view */
 456                 self->map_handle = CreateFileMapping(
 457                         self->file_handle,
 458                         NULL,
 459                         PAGE_READWRITE,
 460                         0,
 461                         0,
 462                         self->tagname);
 463                 if (self->map_handle != NULL) {
 464                         self->data = (char *) MapViewOfFile(self->map_handle,
 465                                                             FILE_MAP_WRITE,
 466                                                             off_hi,
 467                                                             off_lo,
 468                                                             new_size);
 469                         if (self->data != NULL) {
 470                                 self->size = new_size;
 471                                 Py_INCREF(Py_None);
 472                                 return Py_None;
 473                         } else {
 474                                 dwErrCode = GetLastError();
 475                         }
 476                 } else {
 477                         dwErrCode = GetLastError();
 478                 }
 479                 PyErr_SetFromWindowsErr(dwErrCode);
 480                 return NULL;
 481 #endif /* MS_WINDOWS */
 482
 483 #ifdef UNIX
 484 #ifndef HAVE_MREMAP
 485         } else {
 486                 PyErr_SetString(PyExc_SystemError,
 487                                 "mmap: resizing not available--no mremap()");
 488                 return NULL;
 489 #else
 490         } else {
 491                 void *newmap;
 492
 493                 if (ftruncate(self->fd, new_size) == -1) {
 494                         PyErr_SetFromErrno(mmap_module_error);
 495                         return NULL;
 496                 }
 497
 498 #ifdef MREMAP_MAYMOVE
 499                 newmap = mremap(self->data, self->size, new_size, MREMAP_MAYMOVE);
 500 #else
 501                 newmap = mremap(self->data, self->size, new_size, 0);
 502 #endif
 503                 if (newmap == (void *)-1)
 504                 {
 505                         PyErr_SetFromErrno(mmap_module_error);
 506                         return NULL;
 507                 }
 508                 self->data = newmap;
 509                 self->size = new_size;
 510                 Py_INCREF(Py_None);
 511                 return Py_None;
 512 #endif /* HAVE_MREMAP */
 513 #endif /* UNIX */
 514         }
 515 }
 516
 517 static PyObject *
 518 mmap_tell_method(mmap_object *self, PyObject *unused)
 519 {
 520         CHECK_VALID(NULL);
 521         return PyInt_FromSize_t(self->pos);
 522 }
 523
 524 static PyObject *
 525 mmap_flush_method(mmap_object *self, PyObject *args)
 526 {
 527         Py_ssize_t offset = 0;
 528         Py_ssize_t size = self->size;
 529         CHECK_VALID(NULL);
 530         if (!PyArg_ParseTuple(args, "|nn:flush", &offset, &size))
 531                 return NULL;
 532         if ((size_t)(offset + size) > self->size) {
 533                 PyErr_SetString(PyExc_ValueError, "flush values out of range");
 534                 return NULL;
 535         }
 536 #ifdef MS_WINDOWS
 537         return PyInt_FromLong((long) FlushViewOfFile(self->data+offset, size));
 538 #elif defined(UNIX)
 539         /* XXX semantics of return value? */
 540         /* XXX flags for msync? */
 541         if (-1 == msync(self->data + offset, size, MS_SYNC)) {
 542                 PyErr_SetFromErrno(mmap_module_error);
 543                 return NULL;
 544         }
 545         return PyInt_FromLong(0);
 546 #else
 547         PyErr_SetString(PyExc_ValueError, "flush not supported on this system");
 548         return NULL;
 549 #endif
 550 }
 551
 552 static PyObject *
 553 mmap_seek_method(mmap_object *self, PyObject *args)
 554 {
 555         Py_ssize_t dist;
 556         int how=0;
 557         CHECK_VALID(NULL);
 558         if (!PyArg_ParseTuple(args, "n|i:seek", &dist, &how))
 559                 return NULL;
 560         else {
 561                 size_t where;
 562                 switch (how) {
 563                 case 0: /* relative to start */
 564                         if (dist < 0)
 565                                 goto onoutofrange;
 566                         where = dist;
 567                         break;
 568                 case 1: /* relative to current position */
 569                         if ((Py_ssize_t)self->pos + dist < 0)
 570                                 goto onoutofrange;
 571                         where = self->pos + dist;
 572                         break;
 573                 case 2: /* relative to end */
 574                         if ((Py_ssize_t)self->size + dist < 0)
 575                                 goto onoutofrange;
 576                         where = self->size + dist;
 577                         break;
 578                 default:
 579                         PyErr_SetString(PyExc_ValueError, "unknown seek type");
 580                         return NULL;
 581                 }
 582                 if (where > self->size)
 583                         goto onoutofrange;
 584                 self->pos = where;
 585                 Py_INCREF(Py_None);
 586                 return Py_None;
 587         }
 588
 589   onoutofrange:
 590         PyErr_SetString(PyExc_ValueError, "seek out of range");
 591         return NULL;
 592 }
 593
 594 static PyObject *
 595 mmap_move_method(mmap_object *self, PyObject *args)
 596 {
 597         unsigned long dest, src, count;
 598         CHECK_VALID(NULL);
 599         if (!PyArg_ParseTuple(args, "kkk:move", &dest, &src, &count) ||
 600             !is_writeable(self)) {
 601                 return NULL;
 602         } else {
 603                 /* bounds check the values */
 604                 if (/* end of source after end of data?? */
 605                         ((src+count) > self->size)
 606                         /* dest will fit? */
 607                         || (dest+count > self->size)) {
 608                         PyErr_SetString(PyExc_ValueError,
 609                                         "source or destination out of range");
 610                         return NULL;
 611                 } else {
 612                         memmove(self->data+dest, self->data+src, count);
 613                         Py_INCREF(Py_None);
 614                         return Py_None;
 615                 }
 616         }
 617 }
 618
 619 static struct PyMethodDef mmap_object_methods[] = {
 620         {"close",       (PyCFunction) mmap_close_method,        METH_NOARGS},
 621         {"find",        (PyCFunction) mmap_find_method,         METH_VARARGS},
 622         {"rfind",       (PyCFunction) mmap_rfind_method,        METH_VARARGS},
 623         {"flush",       (PyCFunction) mmap_flush_method,        METH_VARARGS},
 624         {"move",        (PyCFunction) mmap_move_method,         METH_VARARGS},
 625         {"read",        (PyCFunction) mmap_read_method,         METH_VARARGS},
 626         {"read_byte",   (PyCFunction) mmap_read_byte_method,    METH_NOARGS},
 627         {"readline",    (PyCFunction) mmap_read_line_method,    METH_NOARGS},
 628         {"resize",      (PyCFunction) mmap_resize_method,       METH_VARARGS},
 629         {"seek",        (PyCFunction) mmap_seek_method,         METH_VARARGS},
 630         {"size",        (PyCFunction) mmap_size_method,         METH_NOARGS},
 631         {"tell",        (PyCFunction) mmap_tell_method,         METH_NOARGS},
 632         {"write",       (PyCFunction) mmap_write_method,        METH_VARARGS},
 633         {"write_byte",  (PyCFunction) mmap_write_byte_method,   METH_VARARGS},
 634         {NULL,     NULL}       /* sentinel */
 635 };
 636
 637 /* Functions for treating an mmap'ed file as a buffer */
 638
 639 static Py_ssize_t
 640 mmap_buffer_getreadbuf(mmap_object *self, Py_ssize_t index, const void **ptr)
 641 {
 642         CHECK_VALID(-1);
 643         if (index != 0) {
 644                 PyErr_SetString(PyExc_SystemError,
 645                                 "Accessing non-existent mmap segment");
 646                 return -1;
 647         }
 648         *ptr = self->data;
 649         return self->size;
 650 }
 651
 652 static Py_ssize_t
 653 mmap_buffer_getwritebuf(mmap_object *self, Py_ssize_t index, const void **ptr)
 654 {
 655         CHECK_VALID(-1);
 656         if (index != 0) {
 657                 PyErr_SetString(PyExc_SystemError,
 658                                 "Accessing non-existent mmap segment");
 659                 return -1;
 660         }
 661         if (!is_writeable(self))
 662                 return -1;
 663         *ptr = self->data;
 664         return self->size;
 665 }
 666
 667 static Py_ssize_t
 668 mmap_buffer_getsegcount(mmap_object *self, Py_ssize_t *lenp)
 669 {
 670         CHECK_VALID(-1);
 671         if (lenp)
 672                 *lenp = self->size;
 673         return 1;
 674 }
 675
 676 static Py_ssize_t
 677 mmap_buffer_getcharbuffer(mmap_object *self, Py_ssize_t index, const void **ptr)
 678 {
 679         if (index != 0) {
 680                 PyErr_SetString(PyExc_SystemError,
 681                                 "accessing non-existent buffer segment");
 682                 return -1;
 683         }
 684         *ptr = (const char *)self->data;
 685         return self->size;
 686 }
 687
 688 static Py_ssize_t
 689 mmap_length(mmap_object *self)
 690 {
 691         CHECK_VALID(-1);
 692         return self->size;
 693 }
 694
 695 static PyObject *
 696 mmap_item(mmap_object *self, Py_ssize_t i)
 697 {
 698         CHECK_VALID(NULL);
 699         if (i < 0 || (size_t)i >= self->size) {
 700                 PyErr_SetString(PyExc_IndexError, "mmap index out of range");
 701                 return NULL;
 702         }
 703         return PyString_FromStringAndSize(self->data + i, 1);
 704 }
 705
 706 static PyObject *
 707 mmap_slice(mmap_object *self, Py_ssize_t ilow, Py_ssize_t ihigh)
 708 {
 709         CHECK_VALID(NULL);
 710         if (ilow < 0)
 711                 ilow = 0;
 712         else if ((size_t)ilow > self->size)
 713                 ilow = self->size;
 714         if (ihigh < 0)
 715                 ihigh = 0;
 716         if (ihigh < ilow)
 717                 ihigh = ilow;
 718         else if ((size_t)ihigh > self->size)
 719                 ihigh = self->size;
 720
 721         return PyString_FromStringAndSize(self->data + ilow, ihigh-ilow);
 722 }
 723
 724 static PyObject *
 725 mmap_subscript(mmap_object *self, PyObject *item)
 726 {
 727         CHECK_VALID(NULL);
 728         if (PyIndex_Check(item)) {
 729                 Py_ssize_t i = PyNumber_AsSsize_t(item, PyExc_IndexError);
 730                 if (i == -1 && PyErr_Occurred())
 731                         return NULL;
 732                 if (i < 0)
 733                         i += self->size;
 734                 if (i < 0 || (size_t)i > self->size) {
 735                         PyErr_SetString(PyExc_IndexError,
 736                                 "mmap index out of range");
 737                         return NULL;
 738                 }
 739                 return PyString_FromStringAndSize(self->data + i, 1);
 740         }
 741         else if (PySlice_Check(item)) {
 742                 Py_ssize_t start, stop, step, slicelen;
 743
 744                 if (PySlice_GetIndicesEx((PySliceObject *)item, self->size,
 745                                  &start, &stop, &step, &slicelen) < 0) {
 746                         return NULL;
 747                 }
 748
 749                 if (slicelen <= 0)
 750                         return PyString_FromStringAndSize("", 0);
 751                 else if (step == 1)
 752                         return PyString_FromStringAndSize(self->data + start,
 753                                                           slicelen);
 754                 else {
 755                         char *result_buf = (char *)PyMem_Malloc(slicelen);
 756                         Py_ssize_t cur, i;
 757                         PyObject *result;
 758
 759                         if (result_buf == NULL)
 760                                 return PyErr_NoMemory();
 761                         for (cur = start, i = 0; i < slicelen;
 762                              cur += step, i++) {
 763                                 result_buf[i] = self->data[cur];
 764                         }
 765                         result = PyString_FromStringAndSize(result_buf,
 766                                                             slicelen);
 767                         PyMem_Free(result_buf);
 768                         return result;
 769                 }
 770         }
 771         else {
 772                 PyErr_SetString(PyExc_TypeError,
 773                                 "mmap indices must be integers");
 774                 return NULL;
 775         }
 776 }
 777
 778 static PyObject *
 779 mmap_concat(mmap_object *self, PyObject *bb)
 780 {
 781         CHECK_VALID(NULL);
 782         PyErr_SetString(PyExc_SystemError,
 783                         "mmaps don't support concatenation");
 784         return NULL;
 785 }
 786
 787 static PyObject *
 788 mmap_repeat(mmap_object *self, Py_ssize_t n)
 789 {
 790         CHECK_VALID(NULL);
 791         PyErr_SetString(PyExc_SystemError,
 792                         "mmaps don't support repeat operation");
 793         return NULL;
 794 }
 795
 796 static int
 797 mmap_ass_slice(mmap_object *self, Py_ssize_t ilow, Py_ssize_t ihigh, PyObject *v)
 798 {
 799         const char *buf;
 800
 801         CHECK_VALID(-1);
 802         if (ilow < 0)
 803                 ilow = 0;
 804         else if ((size_t)ilow > self->size)
 805                 ilow = self->size;
 806         if (ihigh < 0)
 807                 ihigh = 0;
 808         if (ihigh < ilow)
 809                 ihigh = ilow;
 810         else if ((size_t)ihigh > self->size)
 811                 ihigh = self->size;
 812
 813         if (v == NULL) {
 814                 PyErr_SetString(PyExc_TypeError,
 815                                 "mmap object doesn't support slice deletion");
 816                 return -1;
 817         }
 818         if (! (PyString_Check(v)) ) {
 819                 PyErr_SetString(PyExc_IndexError,
 820                                 "mmap slice assignment must be a string");
 821                 return -1;
 822         }
 823         if (PyString_Size(v) != (ihigh - ilow)) {
 824                 PyErr_SetString(PyExc_IndexError,
 825                                 "mmap slice assignment is wrong size");
 826                 return -1;
 827         }
 828         if (!is_writeable(self))
 829                 return -1;
 830         buf = PyString_AsString(v);
 831         memcpy(self->data + ilow, buf, ihigh-ilow);
 832         return 0;
 833 }
 834
 835 static int
 836 mmap_ass_item(mmap_object *self, Py_ssize_t i, PyObject *v)
 837 {
 838         const char *buf;
 839
 840         CHECK_VALID(-1);
 841         if (i < 0 || (size_t)i >= self->size) {
 842                 PyErr_SetString(PyExc_IndexError, "mmap index out of range");
 843                 return -1;
 844         }
 845         if (v == NULL) {
 846                 PyErr_SetString(PyExc_TypeError,
 847                                 "mmap object doesn't support item deletion");
 848                 return -1;
 849         }
 850         if (! (PyString_Check(v) && PyString_Size(v)==1) ) {
 851                 PyErr_SetString(PyExc_IndexError,
 852                                 "mmap assignment must be single-character string");
 853                 return -1;
 854         }
 855         if (!is_writeable(self))
 856                 return -1;
 857         buf = PyString_AsString(v);
 858         self->data[i] = buf[0];
 859         return 0;
 860 }
 861
 862 static int
 863 mmap_ass_subscript(mmap_object *self, PyObject *item, PyObject *value)
 864 {
 865         CHECK_VALID(-1);
 866
 867         if (PyIndex_Check(item)) {
 868                 Py_ssize_t i = PyNumber_AsSsize_t(item, PyExc_IndexError);
 869                 const char *buf;
 870
 871                 if (i == -1 && PyErr_Occurred())
 872                         return -1;
 873                 if (i < 0)
 874                         i += self->size;
 875                 if (i < 0 || (size_t)i > self->size) {
 876                         PyErr_SetString(PyExc_IndexError,
 877                                 "mmap index out of range");
 878                         return -1;
 879                 }
 880                 if (value == NULL) {
 881                         PyErr_SetString(PyExc_TypeError,
 882                                 "mmap object doesn't support item deletion");
 883                         return -1;
 884                 }
 885                 if (!PyString_Check(value) || PyString_Size(value) != 1) {
 886                         PyErr_SetString(PyExc_IndexError,
 887                           "mmap assignment must be single-character string");
 888                         return -1;
 889                 }
 890                 if (!is_writeable(self))
 891                         return -1;
 892                 buf = PyString_AsString(value);
 893                 self->data[i] = buf[0];
 894                 return 0;
 895         }
 896         else if (PySlice_Check(item)) {
 897                 Py_ssize_t start, stop, step, slicelen;
 898
 899                 if (PySlice_GetIndicesEx((PySliceObject *)item,
 900                                          self->size, &start, &stop,
 901                                          &step, &slicelen) < 0) {
 902                         return -1;
 903                 }
 904                 if (value == NULL) {
 905                         PyErr_SetString(PyExc_TypeError,
 906                                 "mmap object doesn't support slice deletion");
 907                         return -1;
 908                 }
 909                 if (!PyString_Check(value)) {
 910                         PyErr_SetString(PyExc_IndexError,
 911                                 "mmap slice assignment must be a string");
 912                         return -1;
 913                 }
 914                 if (PyString_Size(value) != slicelen) {
 915                         PyErr_SetString(PyExc_IndexError,
 916                                 "mmap slice assignment is wrong size");
 917                         return -1;
 918                 }
 919                 if (!is_writeable(self))
 920                         return -1;
 921
 922                 if (slicelen == 0)
 923                         return 0;
 924                 else if (step == 1) {
 925                         const char *buf = PyString_AsString(value);
 926
 927                         if (buf == NULL)
 928                                 return -1;
 929                         memcpy(self->data + start, buf, slicelen);
 930                         return 0;
 931                 }
 932                 else {
 933                         Py_ssize_t cur, i;
 934                         const char *buf = PyString_AsString(value);
 935
 936                         if (buf == NULL)
 937                                 return -1;
 938                         for (cur = start, i = 0; i < slicelen;
 939                              cur += step, i++) {
 940                                 self->data[cur] = buf[i];
 941                         }
 942                         return 0;
 943                 }
 944         }
 945         else {
 946                 PyErr_SetString(PyExc_TypeError,
 947                                 "mmap indices must be integer");
 948                 return -1;
 949         }
 950 }
 951
 952 static PySequenceMethods mmap_as_sequence = {
 953         (lenfunc)mmap_length,                  /*sq_length*/
 954         (binaryfunc)mmap_concat,               /*sq_concat*/
 955         (ssizeargfunc)mmap_repeat,             /*sq_repeat*/
 956         (ssizeargfunc)mmap_item,                       /*sq_item*/
 957         (ssizessizeargfunc)mmap_slice,         /*sq_slice*/
 958         (ssizeobjargproc)mmap_ass_item,        /*sq_ass_item*/
 959         (ssizessizeobjargproc)mmap_ass_slice,      /*sq_ass_slice*/
 960 };
 961
 962 static PyMappingMethods mmap_as_mapping = {
 963         (lenfunc)mmap_length,
 964         (binaryfunc)mmap_subscript,
 965         (objobjargproc)mmap_ass_subscript,
 966 };
 967
 968 static PyBufferProcs mmap_as_buffer = {
 969         (readbufferproc)mmap_buffer_getreadbuf,
 970         (writebufferproc)mmap_buffer_getwritebuf,
 971         (segcountproc)mmap_buffer_getsegcount,
 972         (charbufferproc)mmap_buffer_getcharbuffer,
 973 };
 974
 975 static PyObject *
 976 new_mmap_object(PyTypeObject *type, PyObject *args, PyObject *kwdict);
 977
 978 PyDoc_STRVAR(mmap_doc,
 979 "Windows: mmap(fileno, length[, tagname[, access[, offset]]])\n\
 980 \n\
 981 Maps length bytes from the file specified by the file handle fileno,\n\
 982 and returns a mmap object.  If length is larger than the current size\n\
 983 of the file, the file is extended to contain length bytes.  If length\n\
 984 is 0, the maximum length of the map is the current size of the file,\n\
 985 except that if the file is empty Windows raises an exception (you cannot\n\
 986 create an empty mapping on Windows).\n\
 987 \n\
 988 Unix: mmap(fileno, length[, flags[, prot[, access[, offset]]]])\n\
 989 \n\
 990 Maps length bytes from the file specified by the file descriptor fileno,\n\
 991 and returns a mmap object.  If length is 0, the maximum length of the map\n\
 992 will be the current size of the file when mmap is called.\n\
 993 flags specifies the nature of the mapping. MAP_PRIVATE creates a\n\
 994 private copy-on-write mapping, so changes to the contents of the mmap\n\
 995 object will be private to this process, and MAP_SHARED`creates a mapping\n\
 996 that's shared with all other processes mapping the same areas of the file.\n\
 997 The default value is MAP_SHARED.\n\
 998 \n\
 999 To map anonymous memory, pass -1 as the fileno (both versions).");
1000
1001
1002 static PyTypeObject mmap_object_type = {
1003         PyVarObject_HEAD_INIT(NULL, 0)
1004         "mmap.mmap",                            /* tp_name */
1005         sizeof(mmap_object),                    /* tp_size */
1006         0,                                      /* tp_itemsize */
1007         /* methods */
1008         (destructor) mmap_object_dealloc,       /* tp_dealloc */
1009         0,                                      /* tp_print */
1010         0,                                      /* tp_getattr */
1011         0,                                      /* tp_setattr */
1012         0,                                      /* tp_compare */
1013         0,                                      /* tp_repr */
1014         0,                                      /* tp_as_number */
1015         &mmap_as_sequence,                      /*tp_as_sequence*/
1016         &mmap_as_mapping,                       /*tp_as_mapping*/
1017         0,                                      /*tp_hash*/
1018         0,                                      /*tp_call*/
1019         0,                                      /*tp_str*/
1020         PyObject_GenericGetAttr,                /*tp_getattro*/
1021         0,                                      /*tp_setattro*/
1022         &mmap_as_buffer,                        /*tp_as_buffer*/
1023         Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE | Py_TPFLAGS_HAVE_GETCHARBUFFER,               /*tp_flags*/
1024         mmap_doc,                               /*tp_doc*/
1025         0,                                      /* tp_traverse */
1026         0,                                      /* tp_clear */
1027         0,                                      /* tp_richcompare */
1028         0,                                      /* tp_weaklistoffset */
1029         0,                                      /* tp_iter */
1030         0,                                      /* tp_iternext */
1031         mmap_object_methods,                    /* tp_methods */
1032         0,                                      /* tp_members */
1033         0,                                      /* tp_getset */
1034         0,                                      /* tp_base */
1035         0,                                      /* tp_dict */
1036         0,                                      /* tp_descr_get */
1037         0,                                      /* tp_descr_set */
1038         0,                                      /* tp_dictoffset */
1039         0,                                      /* tp_init */
1040         PyType_GenericAlloc,                    /* tp_alloc */
1041         new_mmap_object,                        /* tp_new */
1042         PyObject_Del,                           /* tp_free */
1043 };
1044
1045
1046 /* extract the map size from the given PyObject
1047
1048    Returns -1 on error, with an appropriate Python exception raised. On
1049    success, the map size is returned. */
1050 static Py_ssize_t
1051 _GetMapSize(PyObject *o, const char* param)
1052 {
1053         if (o == NULL)
1054                 return 0;
1055         if (PyIndex_Check(o)) {
1056                 Py_ssize_t i = PyNumber_AsSsize_t(o, PyExc_OverflowError);
1057                 if (i==-1 && PyErr_Occurred())
1058                         return -1;
1059                 if (i < 0) {
1060                         PyErr_Format(PyExc_OverflowError,
1061                                         "memory mapped %s must be positive",
1062                                         param);
1063                         return -1;
1064                 }
1065                 return i;
1066         }
1067
1068         PyErr_SetString(PyExc_TypeError, "map size must be an integral value");
1069         return -1;
1070 }
1071
1072 #ifdef UNIX
1073 static PyObject *
1074 new_mmap_object(PyTypeObject *type, PyObject *args, PyObject *kwdict)
1075 {
1076 #ifdef HAVE_FSTAT
1077         struct stat st;
1078 #endif
1079         mmap_object *m_obj;
1080         PyObject *map_size_obj = NULL, *offset_obj = NULL;
1081         Py_ssize_t map_size, offset;
1082         int fd, flags = MAP_SHARED, prot = PROT_WRITE | PROT_READ;
1083         int devzero = -1;
1084         int access = (int)ACCESS_DEFAULT;
1085         static char *keywords[] = {"fileno", "length",
1086                                          "flags", "prot",
1087                                          "access", "offset", NULL};
1088
1089         if (!PyArg_ParseTupleAndKeywords(args, kwdict, "iO|iiiO", keywords,
1090                                          &fd, &map_size_obj, &flags, &prot,
1091                                          &access, &offset_obj))
1092                 return NULL;
1093         map_size = _GetMapSize(map_size_obj, "size");
1094         if (map_size < 0)
1095                 return NULL;
1096         offset = _GetMapSize(offset_obj, "offset");
1097         if (offset < 0)
1098                 return NULL;
1099
1100         if ((access != (int)ACCESS_DEFAULT) &&
1101             ((flags != MAP_SHARED) || (prot != (PROT_WRITE | PROT_READ))))
1102                 return PyErr_Format(PyExc_ValueError,
1103                                     "mmap can't specify both access and flags, prot.");
1104         switch ((access_mode)access) {
1105         case ACCESS_READ:
1106                 flags = MAP_SHARED;
1107                 prot = PROT_READ;
1108                 break;
1109         case ACCESS_WRITE:
1110                 flags = MAP_SHARED;
1111                 prot = PROT_READ | PROT_WRITE;
1112                 break;
1113         case ACCESS_COPY:
1114                 flags = MAP_PRIVATE;
1115                 prot = PROT_READ | PROT_WRITE;
1116                 break;
1117         case ACCESS_DEFAULT:
1118                 /* use the specified or default values of flags and prot */
1119                 break;
1120         default:
1121                 return PyErr_Format(PyExc_ValueError,
1122                                     "mmap invalid access parameter.");
1123         }
1124
1125     if (prot == PROT_READ) {
1126         access = ACCESS_READ;
1127     }
1128
1129 #ifdef HAVE_FSTAT
1130 #  ifdef __VMS
1131         /* on OpenVMS we must ensure that all bytes are written to the file */
1132         if (fd != -1) {
1133                 fsync(fd);
1134         }
1135 #  endif
1136         if (fd != -1 && fstat(fd, &st) == 0 && S_ISREG(st.st_mode)) {
1137                 if (map_size == 0) {
1138                         map_size = st.st_size;
1139                 } else if ((size_t)offset + (size_t)map_size > st.st_size) {
1140                         PyErr_SetString(PyExc_ValueError,
1141                                         "mmap length is greater than file size");
1142                         return NULL;
1143                 }
1144         }
1145 #endif
1146         m_obj = (mmap_object *)type->tp_alloc(type, 0);
1147         if (m_obj == NULL) {return NULL;}
1148         m_obj->data = NULL;
1149         m_obj->size = (size_t) map_size;
1150         m_obj->pos = (size_t) 0;
1151         m_obj->offset = offset;
1152         if (fd == -1) {
1153                 m_obj->fd = -1;
1154                 /* Assume the caller wants to map anonymous memory.
1155                    This is the same behaviour as Windows.  mmap.mmap(-1, size)
1156                    on both Windows and Unix map anonymous memory.
1157                 */
1158 #ifdef MAP_ANONYMOUS
1159                 /* BSD way to map anonymous memory */
1160                 flags |= MAP_ANONYMOUS;
1161 #else
1162                 /* SVR4 method to map anonymous memory is to open /dev/zero */
1163                 fd = devzero = open("/dev/zero", O_RDWR);
1164                 if (devzero == -1) {
1165                         Py_DECREF(m_obj);
1166                         PyErr_SetFromErrno(mmap_module_error);
1167                         return NULL;
1168                 }
1169 #endif
1170         } else {
1171                 m_obj->fd = dup(fd);
1172                 if (m_obj->fd == -1) {
1173                         Py_DECREF(m_obj);
1174                         PyErr_SetFromErrno(mmap_module_error);
1175                         return NULL;
1176                 }
1177         }
1178
1179         m_obj->data = mmap(NULL, map_size,
1180                            prot, flags,
1181                            fd, offset);
1182
1183         if (devzero != -1) {
1184                 close(devzero);
1185         }
1186
1187         if (m_obj->data == (char *)-1) {
1188                 m_obj->data = NULL;
1189                 Py_DECREF(m_obj);
1190                 PyErr_SetFromErrno(mmap_module_error);
1191                 return NULL;
1192         }
1193         m_obj->access = (access_mode)access;
1194         return (PyObject *)m_obj;
1195 }
1196 #endif /* UNIX */
1197
1198 #ifdef MS_WINDOWS
1199 static PyObject *
1200 new_mmap_object(PyTypeObject *type, PyObject *args, PyObject *kwdict)
1201 {
1202         mmap_object *m_obj;
1203         PyObject *map_size_obj = NULL, *offset_obj = NULL;
1204         Py_ssize_t map_size, offset;
1205         DWORD off_hi;   /* upper 32 bits of offset */
1206         DWORD off_lo;   /* lower 32 bits of offset */
1207         DWORD size_hi;  /* upper 32 bits of size */
1208         DWORD size_lo;  /* lower 32 bits of size */
1209         char *tagname = "";
1210         DWORD dwErr = 0;
1211         int fileno;
1212         HANDLE fh = 0;
1213         int access = (access_mode)ACCESS_DEFAULT;
1214         DWORD flProtect, dwDesiredAccess;
1215         static char *keywords[] = { "fileno", "length",
1216                                           "tagname",
1217                                           "access", "offset", NULL };
1218
1219         if (!PyArg_ParseTupleAndKeywords(args, kwdict, "iO|ziO", keywords,
1220                                          &fileno, &map_size_obj,
1221                                          &tagname, &access, &offset_obj)) {
1222                 return NULL;
1223         }
1224
1225         switch((access_mode)access) {
1226         case ACCESS_READ:
1227                 flProtect = PAGE_READONLY;
1228                 dwDesiredAccess = FILE_MAP_READ;
1229                 break;
1230         case ACCESS_DEFAULT:  case ACCESS_WRITE:
1231                 flProtect = PAGE_READWRITE;
1232                 dwDesiredAccess = FILE_MAP_WRITE;
1233                 break;
1234         case ACCESS_COPY:
1235                 flProtect = PAGE_WRITECOPY;
1236                 dwDesiredAccess = FILE_MAP_COPY;
1237                 break;
1238         default:
1239                 return PyErr_Format(PyExc_ValueError,
1240                                     "mmap invalid access parameter.");
1241         }
1242
1243         map_size = _GetMapSize(map_size_obj, "size");
1244         if (map_size < 0)
1245                 return NULL;
1246         offset = _GetMapSize(offset_obj, "offset");
1247         if (offset < 0)
1248                 return NULL;
1249
1250         /* assume -1 and 0 both mean invalid filedescriptor
1251            to 'anonymously' map memory.
1252            XXX: fileno == 0 is a valid fd, but was accepted prior to 2.5.
1253            XXX: Should this code be added?
1254            if (fileno == 0)
1255                 PyErr_Warn(PyExc_DeprecationWarning,
1256                            "don't use 0 for anonymous memory");
1257          */
1258         if (fileno != -1 && fileno != 0) {
1259                 fh = (HANDLE)_get_osfhandle(fileno);
1260                 if (fh==(HANDLE)-1) {
1261                         PyErr_SetFromErrno(mmap_module_error);
1262                         return NULL;
1263                 }
1264                 /* Win9x appears to need us seeked to zero */
1265                 lseek(fileno, 0, SEEK_SET);
1266         }
1267
1268         m_obj = (mmap_object *)type->tp_alloc(type, 0);
1269         if (m_obj == NULL)
1270                 return NULL;
1271         /* Set every field to an invalid marker, so we can safely
1272            destruct the object in the face of failure */
1273         m_obj->data = NULL;
1274         m_obj->file_handle = INVALID_HANDLE_VALUE;
1275         m_obj->map_handle = INVALID_HANDLE_VALUE;
1276         m_obj->tagname = NULL;
1277         m_obj->offset = offset;
1278
1279         if (fh) {
1280                 /* It is necessary to duplicate the handle, so the
1281                    Python code can close it on us */
1282                 if (!DuplicateHandle(
1283                         GetCurrentProcess(), /* source process handle */
1284                         fh, /* handle to be duplicated */
1285                         GetCurrentProcess(), /* target proc handle */
1286                         (LPHANDLE)&m_obj->file_handle, /* result */
1287                         0, /* access - ignored due to options value */
1288                         FALSE, /* inherited by child processes? */
1289                         DUPLICATE_SAME_ACCESS)) { /* options */
1290                         dwErr = GetLastError();
1291                         Py_DECREF(m_obj);
1292                         PyErr_SetFromWindowsErr(dwErr);
1293                         return NULL;
1294                 }
1295                 if (!map_size) {
1296                         DWORD low,high;
1297                         low = GetFileSize(fh, &high);
1298                         /* low might just happen to have the value INVALID_FILE_SIZE;
1299                            so we need to check the last error also. */
1300                         if (low == INVALID_FILE_SIZE &&
1301                             (dwErr = GetLastError()) != NO_ERROR) {
1302                                 Py_DECREF(m_obj);
1303                                 return PyErr_SetFromWindowsErr(dwErr);
1304                         }
1305
1306 #if SIZEOF_SIZE_T > 4
1307                         m_obj->size = (((size_t)high)<<32) + low;
1308 #else
1309                         if (high)
1310                                 /* File is too large to map completely */
1311                                 m_obj->size = (size_t)-1;
1312                         else
1313                                 m_obj->size = low;
1314 #endif
1315                 } else {
1316                         m_obj->size = map_size;
1317                 }
1318         }
1319         else {
1320                 m_obj->size = map_size;
1321         }
1322
1323         /* set the initial position */
1324         m_obj->pos = (size_t) 0;
1325
1326         /* set the tag name */
1327         if (tagname != NULL && *tagname != '\0') {
1328                 m_obj->tagname = PyMem_Malloc(strlen(tagname)+1);
1329                 if (m_obj->tagname == NULL) {
1330                         PyErr_NoMemory();
1331                         Py_DECREF(m_obj);
1332                         return NULL;
1333                 }
1334                 strcpy(m_obj->tagname, tagname);
1335         }
1336         else
1337                 m_obj->tagname = NULL;
1338
1339         m_obj->access = (access_mode)access;
1340         /* DWORD is a 4-byte int.  If we're on a box where size_t consumes
1341          * more than 4 bytes, we need to break it apart.  Else (size_t
1342          * consumes 4 bytes), C doesn't define what happens if we shift
1343          * right by 32, so we need different code.
1344          */
1345 #if SIZEOF_SIZE_T > 4
1346         size_hi = (DWORD)((offset + m_obj->size) >> 32);
1347         size_lo = (DWORD)((offset + m_obj->size) & 0xFFFFFFFF);
1348         off_hi = (DWORD)(offset >> 32);
1349         off_lo = (DWORD)(offset & 0xFFFFFFFF);
1350 #else
1351         size_hi = 0;
1352         size_lo = (DWORD)(offset + m_obj->size);
1353         off_hi = 0;
1354         off_lo = (DWORD)offset;
1355 #endif
1356         /* For files, it would be sufficient to pass 0 as size.
1357            For anonymous maps, we have to pass the size explicitly. */
1358         m_obj->map_handle = CreateFileMapping(m_obj->file_handle,
1359                                               NULL,
1360                                               flProtect,
1361                                               size_hi,
1362                                               size_lo,
1363                                               m_obj->tagname);
1364         if (m_obj->map_handle != NULL) {
1365                 m_obj->data = (char *) MapViewOfFile(m_obj->map_handle,
1366                                                      dwDesiredAccess,
1367                                                      off_hi,
1368                                                      off_lo,
1369                                                      0);
1370                 if (m_obj->data != NULL)
1371                         return (PyObject *)m_obj;
1372                 else
1373                         dwErr = GetLastError();
1374         } else
1375                 dwErr = GetLastError();
1376         Py_DECREF(m_obj);
1377         PyErr_SetFromWindowsErr(dwErr);
1378         return NULL;
1379 }
1380 #endif /* MS_WINDOWS */
1381
1382 static void
1383 setint(PyObject *d, const char *name, long value)
1384 {
1385         PyObject *o = PyInt_FromLong(value);
1386         if (o && PyDict_SetItemString(d, name, o) == 0) {
1387                 Py_DECREF(o);
1388         }
1389 }
1390
1391 PyMODINIT_FUNC
1392 initmmap(void)
1393 {
1394         PyObject *dict, *module;
1395
1396         if (PyType_Ready(&mmap_object_type) < 0)
1397                 return;
1398
1399         module = Py_InitModule("mmap", NULL);
1400         if (module == NULL)
1401                 return;
1402         dict = PyModule_GetDict(module);
1403         if (!dict)
1404                 return;
1405         mmap_module_error = PyErr_NewException("mmap.error",
1406                 PyExc_EnvironmentError , NULL);
1407         if (mmap_module_error == NULL)
1408                 return;
1409         PyDict_SetItemString(dict, "error", mmap_module_error);
1410         PyDict_SetItemString(dict, "mmap", (PyObject*) &mmap_object_type);
1411 #ifdef PROT_EXEC
1412         setint(dict, "PROT_EXEC", PROT_EXEC);
1413 #endif
1414 #ifdef PROT_READ
1415         setint(dict, "PROT_READ", PROT_READ);
1416 #endif
1417 #ifdef PROT_WRITE
1418         setint(dict, "PROT_WRITE", PROT_WRITE);
1419 #endif
1420
1421 #ifdef MAP_SHARED
1422         setint(dict, "MAP_SHARED", MAP_SHARED);
1423 #endif
1424 #ifdef MAP_PRIVATE
1425         setint(dict, "MAP_PRIVATE", MAP_PRIVATE);
1426 #endif
1427 #ifdef MAP_DENYWRITE
1428         setint(dict, "MAP_DENYWRITE", MAP_DENYWRITE);
1429 #endif
1430 #ifdef MAP_EXECUTABLE
1431         setint(dict, "MAP_EXECUTABLE", MAP_EXECUTABLE);
1432 #endif
1433 #ifdef MAP_ANONYMOUS
1434         setint(dict, "MAP_ANON", MAP_ANONYMOUS);
1435         setint(dict, "MAP_ANONYMOUS", MAP_ANONYMOUS);
1436 #endif
1437
1438         setint(dict, "PAGESIZE", (long)my_getpagesize());
1439
1440         setint(dict, "ALLOCATIONGRANULARITY", (long)my_getallocationgranularity());
1441
1442         setint(dict, "ACCESS_READ", ACCESS_READ);
1443         setint(dict, "ACCESS_WRITE", ACCESS_WRITE);
1444         setint(dict, "ACCESS_COPY", ACCESS_COPY);
1445 }