Is there a better way to wait for fasm to finish?

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tthsqe

Joined: 20 May 2009
Posts: 767

tthsqe 04 May 2013, 09:16

I'm doing this in a 64 bit app.

Code:

invoke  ShellExecuteA,NULL,'open','E:\fasm\fdbg0024\fasm.exe','"E:\fasm\fdbg0024\test.asm"',NULL,NULL
invoke  Sleep,300    ; wait for FASM
invoke  CreateFileA,'E:\fasm\fdbg0024\test.bin',GENERIC_READ,0,0,OPEN_EXISTING,0,0

edit by revolution: Title is more descriptive

04 May 2013, 09:16

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 20758
Location: In your JS exploiting you and your system

revolution 04 May 2013, 09:34

Doing what?

04 May 2013, 09:34

tthsqe

Joined: 20 May 2009
Posts: 767

tthsqe 04 May 2013, 09:37

oh, I though it was clear from the code.
I am calling fasm from a 64 bit program and waiting for it to finish before opening the output file. Obviously, problems arise if fasm takes more than 0.3 seconds to compile...

04 May 2013, 09:37

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 20758
Location: In your JS exploiting you and your system

revolution 04 May 2013, 09:42

Sure there are much better ways. Probably not using the ShellExecute and instead use CreateProcess would be a start. That way you can wait on the handle and also get the exit code.

04 May 2013, 09:42

nmaps

Joined: 26 Oct 2012
Posts: 8

nmaps 05 May 2013, 20:26

Create a job or semaphore and have your process loop to check if it's finished (or WaitForObject).

05 May 2013, 20:26

typedef

Joined: 25 Jul 2010
Posts: 2893
Location: 0x77760000

typedef 07 May 2013, 04:24

Use CreateProcess and watch it. Since you have control over it. Wink

07 May 2013, 04:24

tthsqe

Joined: 20 May 2009
Posts: 767

tthsqe 07 May 2013, 08:15

Thanks - I'm going to try CreateProcess. Smile

07 May 2013, 08:15

edfed

Joined: 20 Feb 2006
Posts: 4358
Location: Now

edfed 07 May 2013, 08:17

or maybe read the binary file attributes to see if it's date is not older than N seconds. lol

if CreateProcess can return fasm state, it should be the solution.

07 May 2013, 08:17

Feryno

Joined: 23 Mar 2005
Posts: 517
Location: Czech republic, Slovak republic

Feryno 07 May 2013, 09:20

do it as revolution suggested
use the handle returned by CreateProcess and then you can call GetExitCodeProcess http://msdn.microsoft.com/library/windows/desktop/ms683189%28v=vs.85%29.aspx
if the return value is STILL_ACTIVE you must call it later again - e.g. some timeout (as the posted Sleep) or NtYieldExecution (exported from ntdll.dll)

07 May 2013, 09:20

AsmGuru62

Joined: 28 Jan 2004
Posts: 1738
Location: Toronto, Canada

AsmGuru62 07 May 2013, 14:59

It is better to use CreateProcess() on separate thread and just WaitForSingleObject() on the handle.
Otherwise it is a loop on main thread which polls for STILL_ACTIVE and loads the CPU.

07 May 2013, 14:59

typedef

Joined: 25 Jul 2010
Posts: 2893
Location: 0x77760000

typedef 07 May 2013, 23:28

AsmGuru62 wrote:

It is better to use CreateProcess() on separate thread and just WaitForSingleObject() on the handle.
Otherwise it is a loop on main thread which polls for STILL_ACTIVE and loads the CPU.

CreateEvent() / ResetEvent/ RaiseEvent on a separate thread would accomplish this.

Besides, WaitForSingleObject is a blocking API Wink

07 May 2013, 23:28

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