When to lock page under WinNT?

[Zuxy]

On Thu, 21 Oct 2004 19:13:19 +0200, Werner Koch <wk at gnupg.org> wrote:

> No, it won't appear in GnuPG unless there is a portable and working
> way of doing so.
> 
Take a look at these two pieces of code, grabbed from 'gnuwin32'

int
mlock (const void *addr, size_t len)
{
  if (IsWin9x())
	{
	   __set_errno(ENOSYS);
	  return -1;
	}
  if (!VirtualLock (addr, len)) {
  	set_werrno;
	return -1;
  }
  return 0;
}

DWORD
getgranularity (void)
{
	if (!granularity) {
		SYSTEM_INFO si;
		GetSystemInfo (&si);
		granularity = si.dwAllocationGranularity;
		}
	return granularity;
}

__ptr_t
__mmap64 (__ptr_t addr, size_t len, int prot, int flags, int fd,
		__off64_t offset)
{
	__ptr_t map = (__ptr_t) NULL;
	caddr_t gran_addr = (caddr_t) addr;
	HANDLE handle = INVALID_HANDLE_VALUE;
	DWORD cfm_flags = 0, mvf_flags = 0, sysgran = getgranularity ();
	__off64_t gran_offset = flags & MAP_ANON ? 0 :offset, filelen = flags
& MAP_ANON ? len : _filelengthi64(fd);
	int mmlen = len;
	
	switch (prot) {
		case PROT_READ | PROT_WRITE | PROT_EXEC:
		case PROT_WRITE | PROT_EXEC:
			cfm_flags = PAGE_EXECUTE_READWRITE;
			mvf_flags = FILE_MAP_ALL_ACCESS;
			break;
		case PROT_READ | PROT_WRITE:
			cfm_flags = PAGE_READWRITE;
			mvf_flags = FILE_MAP_ALL_ACCESS;
			break;
		case PROT_WRITE:
			cfm_flags = PAGE_READWRITE;
			mvf_flags = FILE_MAP_WRITE;
			break;
		case PROT_READ:
			cfm_flags = PAGE_READONLY;
			mvf_flags = FILE_MAP_READ;
			break;
		case PROT_NONE:
			cfm_flags = PAGE_NOACCESS;
			mvf_flags = FILE_MAP_READ;
			break;
		case PROT_EXEC:
			cfm_flags = PAGE_EXECUTE;
			mvf_flags = FILE_MAP_READ;
			break;
	}
	if (flags & MAP_PRIVATE) {
		if (IsWin9x ())
			cfm_flags = PAGE_WRITECOPY;
		mvf_flags = FILE_MAP_COPY;
	}
	// fprintf (stderr, "Addr before:   %p\n", gran_addr);
	// fprintf (stderr, "Offset before: %#I64X\n", gran_offset);
	if (flags & MAP_FIXED) {
		gran_offset = offset;
		gran_addr = addr;
	}
	else {
		gran_offset = offset & ~(sysgran - 1);
		gran_addr = (caddr_t) (((DWORD) gran_addr / sysgran) * sysgran);
	}
	// fprintf (stderr, "Addr after:    %p\n", gran_addr);
	// fprintf (stderr, "Offset after:  %#I64X\n", gran_offset);
	mmlen = (filelen < gran_offset + len ? filelen - gran_offset : len);

	handle = CreateFileMapping (flags & MAP_ANON ? INVALID_HANDLE_VALUE :
(HANDLE) _get_osfhandle(fd),
		NULL,
		cfm_flags,
		0, mmlen, NULL);
	if (!handle) {
		set_werrno;
		// WinErr ("CreateFileMapping");
		return MAP_FAILED;
	}
	map = (__ptr_t) MapViewOfFileEx (handle, mvf_flags, HIDWORD(gran_offset),
		LODWORD(gran_offset), (SIZE_T) mmlen, (LPVOID) gran_addr);
	if (map == NULL && (flags & MAP_FIXED) ) {
		// fprintf (stderr, "Starting address: %p\n", (LPVOID) gran_addr);
		// WinErr ("First try of MapViewOfFileEx failed");
		map = (__ptr_t) MapViewOfFileEx (handle, mvf_flags, HIDWORD(gran_offset),
			LODWORD(gran_offset), (SIZE_T) mmlen, (LPVOID) NULL);
	}
	CloseHandle(handle);
	if (map == NULL) {
		set_werrno;
		// WinErr ("MapViewOfFileEx");
		return MAP_FAILED;
	}
	return map;
}


-- 
Zuxy
Beauty is truth,
While truth is beauty.
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