Finding (or not) the exact number of args

[Gaël de Chalendar]

Hi,

I'm trying to implement stubs for some missing ordinal functions in shlwapi. 
Reading the NOTES comment in dlls/shlwapi/ordinal.c I don't know if it is a 
good idea, but it allows explorer.exe (Win 98) to show its desktop and it is 
what I'm testing (just for fun. I do not hope to be able to use it right now).

Anyway, it uses at a moment or another unimplemented ordinal functions. To 
implement their stubs, I begins with a lot of args, reducing this number 
until the function is passed. It seems to work but I wonder if I do not add 
only problems with this strategy. If I left the stack in a corrupted state, 
maybe the problem will become visible a lot later...
I was not able to find in docs, mails archives or google groups any useful 
tip to find (simply) the right number of args. Particularly, the URL 
http://www.ece.cmu.edu/afs/ece/usr/dacut/www/src is dead.

So, do I continue ? If yes, in this way or differently ?

Thanks for your advices.

Gael.

PS: I will not read my mail until monday 28.

On Wed, May 23, 2001 at 06:01:51PM +0000, Gaël de Chalendar wrote:
[...]
> Anyway, it uses at a moment or another unimplemented ordinal functions. To 
> implement their stubs, I begins with a lot of args, reducing this number 
> until the function is passed. It seems to work but I wonder if I do not add 
> only problems with this strategy. If I left the stack in a corrupted state, 
> maybe the problem will become visible a lot later...
> I was not able to find in docs, mails archives or google groups any useful 
> tip to find (simply) the right number of args. Particularly, the URL 
> http://www.ece.cmu.edu/afs/ece/usr/dacut/www/src is dead.
>
> So, do I continue ? If yes, in this way or differently ?
> Differently.

You get a nice "crash" when the program hits an unimplemented function.
Do a backtrace, then do a disas of the code that led to the unimplemented
function. Count the number of pushes before that call. That's usually
the number of arguments you need to use.

-- 
Andreas Mohr                        Stauferstr. 6, D-71272 Renningen, Germany
Tel. [phone]                http://home.germany.net/100-30936/

[Gaël de Chalendar]

Le Mercredi 23 Mai 2001 17:19, Andreas Mohr a écrit :
> You get a nice "crash" when the program hits an unimplemented function.
> Do a backtrace, then do a disas of the code that led to the unimplemented
> function. Count the number of pushes before that call. That's usually
> the number of arguments you need to use.

OK. Just to try I removed the stub for SHLWAPI_16. When asking for a 
backtrace (bt) in the wine debugger, I get the following. Where in that di I 
find the address where to disassemble ? 

Unhandled exception: unimplemented function shlwapi.16 called
 in 32-bit code (0x40765056).
In 32-bit mode.
0x40765056 (__wine_unimplemented+0x56 [shlwapi.spec.c:40] in SHLWAPI.DLL): 
jmp 0
x40765050 (__wine_unimplemented+0x50 [shlwapi.spec.c:40] in SHLWAPI.DLL)
43      void __wine_stub_shlwapi_4(void) { __wine_unimplemented("4"); }
Wine-dbg>bt
Backtrace:
=>0 0x40765056 (__wine_unimplemented+0x56(func=0x40770eff) 
[shlwapi.spec.c:40] in SHLWAPI.DLL) (ebp=40566cb8)
  1 0x40765170 (__wine_stub_shlwapi_17 [shlwapi.spec.c:53] in SHLWAPI.DLL) 
(ebp=40566cc8)
  2 0x00403a1a (<Debugged process>.EntryPoint+0x95c in <Debugged process>) 
(ebp=40566e6c)
  3 0x0040312c (<Debugged process>.EntryPoint+0x6e in <Debugged process>) 
(ebp=40566ecc)
  4 0x400d0e92 (start_process+0x1d6 [process.c:403] in libntdll.so) 
(ebp=40566f30)
  5 0x400d46b9 (SYSDEPS_DoCallOnStack+0x25(func=0x400d0cbc, arg=0x0) 
[sysdeps.c:173] in libntdll.so) (ebp=40566ff0)
  6 0x400d4763 (SYSDEPS_CallOnStack+0x2f in libntdll.so) (ebp=bffff17c)
  7 0x400d480d (SYSDEPS_SwitchToThreadStack+0x95(func=0x400d0cbc) 
[sysdeps.c:236] in libntdll.so) (ebp=bffff1b8)
  8 0x400d11ef (PROCESS_InitWine+0x19f(argc=0x2, argv=0xbffff254, 
win16_exe_name=0x804c620, win16_exe_file=0x804c724) [process.c:525] in 
libntdll.so) (ebp=bffff1d4)
  9 0x0804b1ee (Letext [main.c] in wine) (ebp=bffff1ec)
  10 0x40236cbe (NTDLL.DLL.sqrt+0x3362e in libc.so.6) (ebp=bffff228)
  11 0x08049021 (_start+0x21 in wine) (ebp=00000000)


-- 
_______________________________________________
Gael de Chalendar
Groupe LIR - LIMSI/CNRS
BP 133, 91 403 Orsay Cedex (France)
Tel : [phone], Fax : [phone]
E-mail  : mailto:gael(a)limsi.fr
Web : http://www.limsi.fr/Individu/gael/

[eric pouech]

> Wine-dbg>bt
> Backtrace:
> =>0 0x40765056 (__wine_unimplemented+0x56(func=0x40770eff) [shlwapi.spec.c:40] in SHLWAPI.DLL) (ebp=40566cb8)
>   1 0x40765170 (__wine_stub_shlwapi_17 [shlwapi.spec.c:53] in SHLWAPI.DLL) (ebp=40566cc8)
>   2 0x00403a1a (<Debugged process>.EntryPoint+0x95c in <Debugged process>) (ebp=40566e6c)
> this is the right caller... and in fact before the calling point
> doing twice up should bring you here, then you have to disas before 
> the call to __wine_stub_shlwapi_1#

A+
-- 
---------------
Eric Pouech (http://perso.wanadoo.fr/eric.pouech/)
"The future will be better tomorrow", Vice President Dan Quayle

On Fri, Jun 01, 2001 at 04:19:54PM +0000, Gaël de Chalendar wrote:
> Le Mercredi 23 Mai 2001 17:19, Andreas Mohr a écrit :
> > You get a nice "crash" when the program hits an unimplemented function.
> > Do a backtrace, then do a disas of the code that led to the unimplemented
> > function. Count the number of pushes before that call. That's usually
> > the number of arguments you need to use.
>
> OK. Just to try I removed the stub for SHLWAPI_16. When asking for a 
> backtrace (bt) in the wine debugger, I get the following. Where in that di I 
> find the address where to disassemble ?
>
> Unhandled exception: unimplemented function shlwapi.16 called
>  in 32-bit code (0x40765056).
> In 32-bit mode.
> 0x40765056 (__wine_unimplemented+0x56 [shlwapi.spec.c:40] in SHLWAPI.DLL): 
> jmp 0
> x40765050 (__wine_unimplemented+0x50 [shlwapi.spec.c:40] in SHLWAPI.DLL)
> 43      void __wine_stub_shlwapi_4(void) { __wine_unimplemented("4"); }
> Wine-dbg>bt
> Backtrace:
> =>0 0x40765056 (__wine_unimplemented+0x56(func=0x40770eff) 
> [shlwapi.spec.c:40] in SHLWAPI.DLL) (ebp=40566cb8)
>   1 0x40765170 (__wine_stub_shlwapi_17 [shlwapi.spec.c:53] in SHLWAPI.DLL) 
> (ebp=40566cc8)
>   2 0x00403a1a (<Debugged process>.EntryPoint+0x95c in <Debugged process>) 
> (ebp=40566e6c)
>   3 0x0040312c (<Debugged process>.EntryPoint+0x6e in <Debugged process>) 
> (ebp=40566ecc)
>   4 0x400d0e92 (start_process+0x1d6 [process.c:403] in libntdll.so) 
> (ebp=40566f30)
>   5 0x400d46b9 (SYSDEPS_DoCallOnStack+0x25(func=0x400d0cbc, arg=0x0) 
> [sysdeps.c:173] in libntdll.so) (ebp=40566ff0)
> Right before 0x403a1a, of course (since this is where the program calls from).
> So e.g. a disas 0x403a00 should help.

Andreas Mohr

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