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starzboy

Virtual Alloc

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starzboy

hello people

i am trying to use Virtual Alloc to fork around with Files (<200 kb) and i am having problems ....

.data?

vir_address dd ?

invoke GetFileSize,hFile,0

mov FileSize,eax

invoke VirtualAlloc,NULL,FileSize,MEM_COMMIT,PAGE_READWRITE

mov vir_address,eax

invoke ReadFile,hFile,esi,ebx,addr dwBytes,0

mov edi,offset SerialBuffer

mov ecx,offset vir_address

loop1:

mov al,byte ptr ds:[esi]

mov byte ptr ds:[edi],al

....calculations .....

mov byte ptr ds:[ecx],al

inc edi

inc esi

loop1

but it fails ...

can someone explain where i am going wrong ...

but when i continue with files below 100Kb the code executes fine ...

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human

from parts of code its hard to say where you have bug, use olly to debug or use that code,just change global to virtual

invoke CreateFile,o file_name,GENERIC_READ,0,0,OPEN_EXISTING,FILE_ATTRIBUTE_ARCHIVE,0

mov file_handle,eax

invoke GetFileSize,file_handle,0

push eax

invoke GlobalAlloc,GMEM_FIXED,eax

mov src,eax

pop eax

invoke ReadFile,file_handle,src,eax,o buff,0

invoke CloseHandle,file_handle

Edited by human (see edit history)

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starzboy

nah ... i jusss posted in short wasnt at home ...

here is:

invoke CreateFile,addr szFileName1,GENERIC_READ or GENERIC_WRITE,FILE_SHARE_READ or FILE_SHARE_WRITE,NULL,OPEN_ALWAYS,FILE_ATTRIBUTE_ARCHIVE,NULL
mov hFile,eax
invoke GetFileSize,hFile,0
mov ebx,eax ; Store FileSize
mov FileSize,ebx
invoke GlobalAlloc,0,eax
mov esi,eaxinvoke VirtualAlloc,NULL,FileSize,MEM_COMMIT,PAGE_READWRITE
mov vir_address,eaxinvoke ReadFile,hFile,esi,ebx,addr dwBytes,0
mov edi,offset SerialBuffer
mov ecx,offset vir_address

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starzboy

sorry people ... for the disturbance ... thanx to Angel for pointing out the mistake ... all working fine now ...

Cheers

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Teddy Rogers

What was the mistake?

Ted.

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starzboy

hi Ted

the mistake was'nt in Allocation ... it was on the next buffer [fixed buffer] which overflowed and crashed ...

mov edi,offset SerialBuffer ... this was wrong

i was so flaming at VirtualAlloc that i forgot to see the other buffers

now all ok ..

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