mingw_mmap.c

   1 /** This code is adapted from:
   2   * https://kerneltrap.org/mailarchive/git/2008/11/21/4186494
   3   * Original code by Vasyl Vavrychuk.
   4   *
   5   * This file is part of Rockstars.
   6   * Coded in Hungarian Notation so it looks stupid. :D
   7   *
   8   * If you haven't seen the header file, call mmap() and munmap() not the
   9   * function names below!
  10   */
  11
  12 #include <stdio.h>
  13 #include "mingw_mmap.h"
  14
  15 extern int getpagesize();
  16
  17 /**
  18   * Use CreateFileMapping and MapViewOfFile to simulate POSIX mmap().
  19   * Why Microsoft won't just implement these is beyond everyone's comprehension.
  20   * @return pointer or NULL
  21   */
  22 void *mingw_mmap(void *pStart, size_t sLength, int nProt, int nFlags, int nFd, off_t oOffset) {
  23   (void)nProt;
  24   HANDLE hHandle;
  25
  26   if (pStart != NULL || !(nFlags & MAP_PRIVATE)) {
  27         printf("Invalid usage of mingw_mmap");
  28     return NULL;
  29   }
  30
  31   if (oOffset % getpagesize() != 0) {
  32     printf("Offset does not match the memory allocation granularity");
  33     return NULL;
  34   }
  35
  36   hHandle = CreateFileMapping((HANDLE)_get_osfhandle(nFd), NULL, PAGE_WRITECOPY, 0, 0, NULL);
  37   if (hHandle != NULL) {
  38     pStart = MapViewOfFile(hHandle, FILE_MAP_COPY, 0, oOffset, sLength);
  39   }
  40
  41   return pStart;
  42 }
  43
  44 /**
  45   * Use UnmapViewOfFile to undo mmap() above.
  46   * @param pStart
  47   * @param length - Not used, kept for compatibility.
  48   * @return boolean; no checks are performed.
  49   */
  50 int mingw_munmap(void *pStart, size_t sLength) {
  51   (void)sLength;
  52
  53   if (UnmapViewOfFile(pStart) != 0)
  54     return FALSE;
  55
  56   return TRUE;
  57 }