Question

I came across a strange problem with ReadFile(). The textfile is opened correctly but it reads only 4 bytes instead of number of bytes declared in MemorySize. The same code in C is executed properly. Somebody knows what’s wrong?

Regards

.DATA
FileName DB "test.txt",0
MemorySize  DWORD 10

.DATA?
hFile    HANDLE ?
pMemory  DWORD  ?
SizeR    DWORD  ?

.CODE
start:

INVOKE CreateFile, ADDR FileName,\ 
    GENERIC_READ, 0, NULL,\
    OPEN_EXISTING, 0, NULL
mov hFile, eax
INVOKE GlobalAlloc, GMEM_FIXED or GMEM_ZEROINIT, MemorySize+1
mov pMemory, eax
INVOKE ReadFile, hFile, ADDR pMemory, MemorySize, ADDR SizeR, NULL
INVOKE MessageBox, 0, ADDR pMemory, 0, 0
INVOKE LocalFree, pMemory
INVOKE CloseHandle, hFile
ret
end start

Answer 1

INVOKE ReadFile, hFile, ADDR pMemory, MemorySize, ADDR SizeR, NULL
INVOKE MessageBox, 0, ADDR pMemory, 0, 0

In these two lines, you are passing a pointer to a pointer for pMemory. GlobalAlloc returns a pointer to memory and ReadFile expects a pointer NOT a pointer to a pointer. Remove ADDR and it should work.

INVOKE GlobalAlloc, GMEM_FIXED or GMEM_ZEROINIT, MemorySize+1

This is wrong also. You cannot do MemorySize + 1 as you would to in a High Level Language. In this case you need to do:

inc     MemorySize

before your call to GlobalAlloc