MapViewOfFile shared between 32bit and 64bit processes
- by MK
Hi, I'm trying to use MapViewOfFile in a 64 bit process on a file that is already mapped to memory of another 32 bit process. It fails and gives me an "access denied" error. Is this a known Windows limitation or am I doing something wrong? Same code works fine with 2 32bit processes.
The code sort of looks like this:
hMapFile = OpenFileMapping(FILE_MAP_ALL_ACCESS, FALSE, szShmName);
if (NULL == hMapFile)
{ /* failed to open - create new (this happens in the 32 bit app) */
SECURITY_ATTRIBUTES sa;
sa.nLength = sizeof(SECURITY_ATTRIBUTES);
sa.bInheritHandle = FALSE;
/* give access to members of administrators group */
BOOL success = ConvertStringSecurityDescriptorToSecurityDescriptor(
"D:(A;OICI;GA;;;BA)",
SDDL_REVISION_1,
&(sa.lpSecurityDescriptor),
NULL);
HANDLE hShmFile = CreateFile(FILE_FAXCOM_SHM,
FILE_ALL_ACCESS, 0,
&sa,
OPEN_ALWAYS, 0, NULL);
hMapFile = CreateFileMapping(hShmFile, &sa, PAGE_READWRITE,
0,
SHM_SIZE,
szShmName);
CloseHandle(hShmFile);
}
// this one fails in 64 bit app
pShm = MapViewOfFile(hMapFile, FILE_MAP_ALL_ACCESS, 0, 0, SHM_SIZE);
