Tracing Win32 API while debugging a process

Load an executable or attach WinDbg to an existing process and use logexts debugging extension (in output below all API parameters and return values are omitted for visual clarity):

0:001> !logexts.loge
0:001> !logc e *
All categories enabled.
0:001> !logo e d
  Debugger            Enabled
  Text file           Disabled
  Verbose log         Enabled
0:001> g
Thrd 7c0 77555B59 BeginPaint( 0x001103AA) ...
Thrd 7c0 77555B65 GetClientRect( 0x001103AA) ...
Thrd 7c0 77555B96 DrawEdge( 0x01010072 ...) ...
Thrd 7c0 77555C8A DrawFrameControl( 0x01010072 ...) ...
Thrd 7c0 77555CE1 EndPaint( 0x001103AA ... ) ...
Thrd 7c0 004165F2 TlsGetValue( 0x00000006) ...
Thrd 7c0 4B8D54B5 CallNextHookEx( ... ) ...
Thrd 7c0 0040D7CC GetMessageW( ... ) ...

You can break in and put a breakpoint at a return address:

0:001> bp 0040D7CC
0:001> g
Thrd 7c0 0040D7CC GetMessageW( ... ) ...
Breakpoint 0 hit
0040d7cc 85c0            test    eax,eax
0:000> u 0040D7C0 0040D7CC
0040d7c0 50              push    eax
0040d7c1 50              push    eax
0040d7c2 8d7730          lea     esi,[edi+30h]
0040d7c5 56              push    esi
0040d7c6 ff15f8434300    call    dword ptr
[ProcessHistory+0x343f8 (004343f8)]
0:000> dd 004343f8
004343f8  3c001950 3c0018c4 3c00193c 3c0014dc
0:000> u 3c001950
3c001950 b889020000      mov     eax,289h
3c001955 e98e410014      jmp     logexts!LogHook
3c00195a b88a020000      mov     eax,28Ah
3c00195f e984410014      jmp     logexts!LogHook
3c001964 b88b020000      mov     eax,28Bh
3c001969 e97a410014      jmp     logexts!LogHook
3c00196e b88c020000      mov     eax,28Ch
3c001973 e970410014      jmp     logexts!LogHook

Here we can see that logexts patches import table.

And you can trace different API categories:

0:001> !logexts.logc
  1 AdvApi32                        Enabled
  2 AtomFunctions                   Enabled
  3 AVIFileExports                  Enabled
  4 Clipboard                       Enabled
  5 ComponentObjectModel            Enabled
  6 DebuggingAndErrorHandling       Enabled
  7 DeviceFunctions                 Enabled
  8 Direct3D                        Enabled
  9 DirectDraw                      Enabled
 10 DirectPlay                      Enabled
 11 DirectSound                     Enabled
 12 GDI                             Enabled
 13 HandleAndObjectFunctions        Enabled
 14 HookingFunctions                Enabled
 15 IOFunctions                     Enabled
 16 MemoryManagementFunctions       Enabled
 17 Multimedia                      Enabled
 18 Printing                        Enabled
 19 ProcessesAndThreads             Enabled
 20 RegistryFunctions               Enabled
 21 Shell                           Enabled
 22 StringManipulation              Enabled
 23 ThreadLocalStorage              Enabled
 24 User32                          Enabled
 25 User32StringExports             Enabled
 26 Version                         Enabled
 27 WinSock2                        Enabled

- Dmitry Vostokov -

One Response to “Tracing Win32 API while debugging a process”

  1. Software Generalist » Blog Archive » Reading Notebook: 09-Feb-09 Says:

    […] OS calls (pp. 104 - 106) - On Windows we can trace API while debugging using WinDbg extensions: Process Monitor can also be used to trace API subsets like File and Registry […]

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