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mmap-windows.c
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mmap-windows.c
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/* mmap() replacement for Windows
*
* Author: Mike Frysinger <[email protected]>
* Placed into the public domain
*/
/* References:
* CreateFileMapping: http://msdn.microsoft.com/en-us/library/aa366537(VS.85).aspx
* CloseHandle: http://msdn.microsoft.com/en-us/library/ms724211(VS.85).aspx
* MapViewOfFile: http://msdn.microsoft.com/en-us/library/aa366761(VS.85).aspx
* UnmapViewOfFile: http://msdn.microsoft.com/en-us/library/aa366882(VS.85).aspx
*/
#include <io.h>
#include <windows.h>
#include <sys/types.h>
#define PROT_READ 0x1
#define PROT_WRITE 0x2
/* This flag is only available in WinXP+ */
#ifdef FILE_MAP_EXECUTE
#define PROT_EXEC 0x4
#else
#define PROT_EXEC 0x0
#define FILE_MAP_EXECUTE 0
#endif
#define MAP_SHARED 0x01
#define MAP_PRIVATE 0x02
#define MAP_ANONYMOUS 0x20
#define MAP_ANON MAP_ANONYMOUS
#define MAP_FAILED ((void *) -1)
#ifdef __USE_FILE_OFFSET64
# define DWORD_HI(x) (x >> 32)
# define DWORD_LO(x) ((x) & 0xffffffff)
#else
# define DWORD_HI(x) (0)
# define DWORD_LO(x) (x)
#endif
static void *mmap(void *start, size_t length, int prot, int flags, int fd, off_t offset)
{
if (prot & ~(PROT_READ | PROT_WRITE | PROT_EXEC))
return MAP_FAILED;
if (fd == -1) {
if (!(flags & MAP_ANON) || offset)
return MAP_FAILED;
} else if (flags & MAP_ANON)
return MAP_FAILED;
DWORD flProtect;
if (prot & PROT_WRITE) {
if (prot & PROT_EXEC)
flProtect = PAGE_EXECUTE_READWRITE;
else
flProtect = PAGE_READWRITE;
} else if (prot & PROT_EXEC) {
if (prot & PROT_READ)
flProtect = PAGE_EXECUTE_READ;
else if (prot & PROT_EXEC)
flProtect = PAGE_EXECUTE;
} else
flProtect = PAGE_READONLY;
off_t end = length + offset;
HANDLE mmap_fd, h;
if (fd == -1)
mmap_fd = INVALID_HANDLE_VALUE;
else
mmap_fd = (HANDLE)_get_osfhandle(fd);
h = CreateFileMapping(mmap_fd, NULL, flProtect, DWORD_HI(end), DWORD_LO(end), NULL);
if (h == NULL)
return MAP_FAILED;
DWORD dwDesiredAccess;
if (prot & PROT_WRITE)
dwDesiredAccess = FILE_MAP_WRITE;
else
dwDesiredAccess = FILE_MAP_READ;
if (prot & PROT_EXEC)
dwDesiredAccess |= FILE_MAP_EXECUTE;
if (flags & MAP_PRIVATE)
dwDesiredAccess |= FILE_MAP_COPY;
void *ret = MapViewOfFile(h, dwDesiredAccess, DWORD_HI(offset), DWORD_LO(offset), length);
if (ret == NULL) {
CloseHandle(h);
ret = MAP_FAILED;
}
return ret;
}
static void munmap(void *addr, size_t length)
{
UnmapViewOfFile(addr);
/* ruh-ro, we leaked handle from CreateFileMapping() ... */
}
#undef DWORD_HI
#undef DWORD_LO