utils/mmap-windows.c

   1 /* mmap() replacement for Windows
   2  *
   3  * Author: Mike Frysinger <vapier@gentoo.org>
   4  * Placed into the public domain
   5  */
   6
   7 /* References:
   8  * CreateFileMapping: http://msdn.microsoft.com/en-us/library/aa366537(VS.85).aspx
   9  * CloseHandle:       http://msdn.microsoft.com/en-us/library/ms724211(VS.85).aspx
  10  * MapViewOfFile:     http://msdn.microsoft.com/en-us/library/aa366761(VS.85).aspx
  11  * UnmapViewOfFile:   http://msdn.microsoft.com/en-us/library/aa366882(VS.85).aspx
  12  */
  13
  14 #include <io.h>
  15 #include <windows.h>
  16 #include <sys/types.h>
  17
  18 #define PROT_READ     0x1
  19 #define PROT_WRITE    0x2
  20 /* This flag is only available in WinXP+ */
  21 #ifdef FILE_MAP_EXECUTE
  22 #define PROT_EXEC     0x4
  23 #else
  24 #define PROT_EXEC        0x0
  25 #define FILE_MAP_EXECUTE 0
  26 #endif
  27
  28 #define MAP_SHARED    0x01
  29 #define MAP_PRIVATE   0x02
  30 #define MAP_ANONYMOUS 0x20
  31 #define MAP_ANON      MAP_ANONYMOUS
  32 #define MAP_FAILED    ((void *) -1)
  33
  34 #ifdef __USE_FILE_OFFSET64
  35 # define DWORD_HI(x) (x >> 32)
  36 # define DWORD_LO(x) ((x) & 0xffffffff)
  37 #else
  38 # define DWORD_HI(x) (0)
  39 # define DWORD_LO(x) (x)
  40 #endif
  41
  42 static void *mmap(void *start, size_t length, int prot, int flags, int fd, off_t offset)
  43 {
  44         if (prot & ~(PROT_READ | PROT_WRITE | PROT_EXEC))
  45                 return MAP_FAILED;
  46         if (fd == -1) {
  47                 if (!(flags & MAP_ANON) || offset)
  48                         return MAP_FAILED;
  49         } else if (flags & MAP_ANON)
  50                 return MAP_FAILED;
  51
  52         DWORD flProtect;
  53         if (prot & PROT_WRITE) {
  54                 if (prot & PROT_EXEC)
  55                         flProtect = PAGE_EXECUTE_READWRITE;
  56                 else
  57                         flProtect = PAGE_READWRITE;
  58         } else if (prot & PROT_EXEC) {
  59                 if (prot & PROT_READ)
  60                         flProtect = PAGE_EXECUTE_READ;
  61                 else if (prot & PROT_EXEC)
  62                         flProtect = PAGE_EXECUTE;
  63         } else
  64                 flProtect = PAGE_READONLY;
  65
  66         off_t end = length + offset;
  67         HANDLE mmap_fd, h;
  68         if (fd == -1)
  69                 mmap_fd = INVALID_HANDLE_VALUE;
  70         else
  71                 mmap_fd = (HANDLE)_get_osfhandle(fd);
  72         h = CreateFileMapping(mmap_fd, NULL, flProtect, DWORD_HI(end), DWORD_LO(end), NULL);
  73         if (h == NULL)
  74                 return MAP_FAILED;
  75
  76         DWORD dwDesiredAccess;
  77         if (prot & PROT_WRITE)
  78                 dwDesiredAccess = FILE_MAP_WRITE;
  79         else
  80                 dwDesiredAccess = FILE_MAP_READ;
  81         if (prot & PROT_EXEC)
  82                 dwDesiredAccess |= FILE_MAP_EXECUTE;
  83         if (flags & MAP_PRIVATE)
  84                 dwDesiredAccess |= FILE_MAP_COPY;
  85         void *ret = MapViewOfFile(h, dwDesiredAccess, DWORD_HI(offset), DWORD_LO(offset), length);
  86         if (ret == NULL) {
  87                 CloseHandle(h);
  88                 ret = MAP_FAILED;
  89         }
  90         return ret;
  91 }
  92
  93 static void munmap(void *addr, size_t length)
  94 {
  95         UnmapViewOfFile(addr);
  96         /* ruh-ro, we leaked handle from CreateFileMapping() ... */
  97 }
  98
  99 #undef DWORD_HI
 100 #undef DWORD_LO