ASM Community

PrintStringByAddr
Is not going to work untill you call PrintDec or probably another macro that make debuger window.

This is working ;

INITHEAP LhHeap,LpHeap,300
; <----Load some string into LpHeap
PrintDec eax
PrintStringByAddr LpHeap
DEINITHEAP LhHeap,LpHeap


This is not;
INITHEAP LhHeap,LpHeap,300
; <----Load some string into LpHeap
PrintStringByAddr LpHeap
DEINITHEAP LhHeap,LpHeap



LpHeap and LhHeap are local variables

Maby it's becouse memory is dynamically alocated

This message tells us that instruction from addres xxxxx refers to memory xxxxxxxx memory can't be written

Yep your example is working properly. i Can post my source with this problem if you wish becouse i dont know what's the problem.

OK here it is. You have to build it if you want to not working one look in line 1826 and 1827 i have " ; " this lines. So as i was talking before

This is working :
PrintDec eax
PrintStringByAddr LpHeap

This one alone is not:
PrintStringByAddr LpHeap



To see the problem you have to run the prog, db_click on item in list view and then press bottom left button "Kasuj Baze"

It's probably becouse i didn't preserv some important registers
I'm using XP btw.

Hi AceEmbler,

I downloaded your example and I get the same GPF as you did using Win2K but even if VKim is not called in the program.

Hi AceEmbler,

You did not preserve EBX in your DlgProc:

20 DlgProc proc uses ebx hWin:HWND,uMsg:UINT,wParam:WPARAM,lParam:LPARAM

This takes care of the problem completely ;)

Hi Vkim !
Sorry for my bad English !
I build your test.asm with Debug info, and run it under MemProof and Purify. All of them report error at the call GlobalFree in PrintStringByAddr macro. I tried to run it with OllyDbg. At the first run, OllyDbg report exception in GlobalFree function, but at many later run, the problem not occur. I step to the macro, and found the macro writed exceed the size of buffer which was allocatted by GlobalAlloc one byte. Here is the asm code in OllyDbg:
<pre>
00401035 |. 60 pushad
00401036 |. FF35 0B304000 push dword ptr ds:
0040103C |. FF35 0B304000 push dword ptr ds: ; /String = "Hello!"
00401042 |. E8 A7000000 call test.lstrlenA ; \lstrlenA
00401047 |. 50 push eax ; => eax = 6
00401048 |. 83C0 18 add eax, 18 ; => eax = 1Eh, = 30
0040104B |. 50 push eax ; /MemSize = 133CC0 (1260736.)
0040104C |. 6A 40 push 40 ; |Flags = GPTR
0040104E |. E8 7D000000 call test.GlobalAlloc ; \GlobalAlloc
00401053 |. 8BD8 mov ebx, eax
00401055 |. 50 push eax
00401056 |. 8BC3 mov eax, ebx
00401058 |. C700 70486561 mov dword ptr ds:, 61654870 ; "pHea"
0040105E |. 66:C740 04 7000 mov word ptr ds:, 70 ; "a"
00401064 |. 58 pop eax ; 00133B7E
00401065 |. C740 05 203D2000 mov dword ptr ds:, 203D20 ; "^ =^"
0040106C |. 5A pop edx ; 00133B7E
0040106D |. 58 pop eax ; 00133B7E
0040106E |. 50 push eax ; /StringToAdd = "Hello!"
0040106F |. 53 push ebx ; |ConcatString = "pHeap = "
00401070 |. E8 73000000 call test.lstrcatA ; \lstrcatA => "pHeap = Hello!"
00401075 |. 53 push ebx
00401076 |. 83C3 08 add ebx, 8
00401079 |. 03DA add ebx, edx
0040107B |. 50 push eax
0040107C |. 8BC3 mov eax, ebx
0040107E |. C700 20287465 mov dword ptr ds:, 65742820 ; "^(te"
00401084 |. C740 04 73742E61 mov dword ptr ds:, 612E7473; "st.a"
0040108B |. C740 08 736D2C20 mov dword ptr ds:, 202C6D73; "sm,"
00401092 |. C740 0C 33342900 mov dword ptr ds:, 293433 ; "34)"and a 0 byte => exceed here, 31 byte.
00401099 |. 58 pop eax ; 00133B7E
0040109A |. 5B pop ebx ; 00133B7E
0040109B |. 53 push ebx ; /Arg1 = 00133CC0 ASCII "pHeap = Hello!"
0040109C |. E8 53000000 call test.DebugPrint ; \DebugPrint
004010A1 |. 53 push ebx ; /hMem = 00133CC0
004010A2 |. E8 2F000000 call test.GlobalFree ; \GlobalFree
004010A7 |. 61 popad
</pre>

If I have a mistake, please give me your idea.
Best regards !
TQN

Hi Vkim,

I have been getting a GPF in GoAsm and have traced it back to the buffers in (in my cases) DumpFPU and DumpMem, but the problem seems to be the interaction of the obj's and not a real error anywhere. I redid both routines using GlobalAlloc to allocate runtime buffers and the problem disappeared. For example :

invoke GlobalAlloc,GPTR,256

mov pdbbuf,eax

Was used in place of

dbbuf byte 128 dup (?)

This and the verification of the direction flag makes the application much more robust. However, I believe that in my case GoAsm was not allocating the memory from the BSS segment as it could not "see" it, it is never written to or read from except indirectly through ADDR dbbuf. Since these seem to work well now I will be going through the rest of the code and finding other problems in porting the object file to GoAsm, there should not be many.

If you like I will email the resulting project to you, it also banishes the need for the masm32 library (FloatToStr is referenced but not resident), something that is not desirable for porting to other assemblers.

donkey,
1. You are absolutely right when you say about direction flag. This problem will be fixed in the next version.
2. As you understand I allocate runtime buffer because I don't know the length of the text. It can be autoexec.bat for example.
3. Of course, send me your project if you think I can help you.

Hi VKim !
I tested with MASM 6.15.8803 and 7.10.3077, Windows 2000 Server Service pack 4
The string output in my machine is:
pHeap^=^Hello!.^(test.asm,^31) and a 0 byte (^=space character), so total length is 31 bytes.
In debug.inc, at PrintStringByAddr, if I replace the original code:
if DBGWIN_EXT_INFO eq 1
add eax, @SizeStr(&Var)+4+@SizeStr(%info)
else
add eax, @SizeStr(&Var)+4
endif
with:
if DBGWIN_EXT_INFO eq 1
add eax, @SizeStr(&Var)+8+@SizeStr(%info)
else
add eax, @SizeStr(&Var)+8
endif
then the problem will not happen.
Best regards !
TQN