ASM Community

help me please, how can it be when such a code:

	push	0
	push	FILE_ATTRIBUTE_NORMAL
	push	CREATE_ALWAYS
	push	0	
	push	FILE_SHARE_READ
	push	GENERIC_WRITE
	push	offset sof
	call	CreateFile

returns me -1 (ERROR_NOACCESS (000003E6))
but a have full admin rights!
the same problame is when i do like that

xor	esi, esi
		push	esi
		push	esi
		push	esi
		push	PAGE_READONLY
		push	esi
		push	fh
		call	CreateFileMapping		
		push	esi
		push	esi
		push	esi
		push	FILE_MAP_READ
		push	eax
		call	MapViewOfFile

CreateFileMapping return handle, but MapViewOfFile returns -1
why is that?

but it does not

I uses same parameters to create many files in many od my apps and they always worked. Double-check the filename. Or -as implicitly sugested by donkey- post some binary here, so we can see it.

The FILE_SHARE flags are only for subsequent opens, that is the file is already open by your process and another asks for permission to open a handle. In most cases I set it to 0 when writing as I want exclusive access while I am updating a file. In any case, since you are probably using it to share information between processes (mapping the file) this is not an option for you as the secondary process must be capable of reading the data. Since this appears to be a security issue, ie access is denied, it does little to post any code as my system is probably set up differently than yours. You can verify that you have admin priviledges by calling ordinal 680 of Shell32.DLL (no parameters), a return value of TRUE (non-zero) indicates that you are an admin. The other question is do you have write permissions in the folder where you are creating the file ?

Donkey

The sub esp,10 should have absolutely no affect at all on the CreateFile call. It happens before the first push and contrary to what you have said it does not "allocate space on the stack", it merely moves the stack pointer. The stack is allocated by the PE loader at load time and cannot be modified at run time, it generally defaults to 1MB but that is swithable in the linker. When you PUSH a value onto the stack the value of ESP is updated accordingly and since the CreateFile call uses the STDCALL convention it is corrected on exiting the function. In my opinion if you require that correction to ESP there is quite a bit about your application that you have opted not to show us here and so we cannot be of any help to you. All in all the add esp/sub esp combination does nothing but eat opcodes, it is not within the same scope as the API call.

Donkey

oh yeah, that's it..
sub esp, 4
works fine )

Donkey, i use that add/sub esp combination for local variables, like C++ compilator do

p.s.
i use w2k