Re: Stackwalk64 problems

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From: Faisal Masoor (fmansoor_at_softpak.com)
Date: 05/21/04

  • Next message: hector: "Re: How to terminate a socket in CLOSE_WAIT state" 
    Date: Fri, 21 May 2004 09:57:13 +0500

    Hello John

    This problem is not due to dbghelp.dll it is due to compiler optimization
    your program is
    producing correct stack depth but in release build the compiler is
    optimizing your code thus is not calling the testAfter function
    recursively take a look at the disassembly of your testAfter function in
    release build.

    -------------------------------Relase
    Build-------------------------------------------------------------------
    52: void testAfter(int depth)
    53: {
    00401120 jmp stackTest (00401000) //Look Here This directly jumps
    to stackTest
    --- No source
    ile -----------------------------------------------------------------------
    ---------------------------------
    00401125 nop
    00401126 nop
    00401127 nop
    00401128 nop
    00401129 nop
    0040112A nop
    0040112B nop
    0040112C nop
    0040112D nop
    0040112E nop
    0040112F nop
    --- E:\My
    rojects\StkWalkProb\a.cpp -------------------------------------------------
    -------------------------------------
    54: if(depth > 0)
    55: {
    56: depth--;
    57: testAfter(depth);
    58: }
    59: else
    60: {
    61: stackTest();
    62: }
    63: }
    64:
    ----------------------------------------------------------------------------
    ---------------

    Faisal Mansoor
    ----------------------------------------------------------------------------
    ---------------

    "John Kirk" <john@-removethis-demonware.net> wrote in message
    news:Xns94EFB9116CFADjohndemonwarenet@194.125.133.14...
    > Hi,
    >
    > Setup: MSVC6, WinXP (sp2), latest platform SDK (Feb 2003)
    >
    > I'm trying to use dbghelp.dll to get a stack trace, unfortunately I think
    > StackWalk64 is misbehaving. The output of the program below differs
    > depending on the version of dbghelp.dll used, neither of which are
    correct:
    >
    > dbghelp.dll ver 5.1 outputs:
    > Stack depth = 2
    >
    > dbghelp.dll ver 6.2 outputs:
    > Stack depth = 3
    >
    > The output stack depth should at least 100. I have seen several examples
    > of StackWalk and StackWalk64 that use separate threads but that's not an
    > option for me. Have a forgotten to initialize something? What am I doing
    > wrong?
    >
    > Thanks in advance,
    >
    > John.
    >
    > Here's the code:
    >
    > #include <stdio.h>
    > #include <windows.h>
    > #include <Dbghelp.h>
    >
    > #pragma comment(lib, "dbghelp")
    >
    > void stackTest()
    > {
    > HANDLE hProcess = GetCurrentProcess();
    > HANDLE hThread = GetCurrentThread();
    >
    > CONTEXT context;
    > memset(&context, 0, sizeof(CONTEXT));
    > context.ContextFlags = CONTEXT_FULL;
    >
    > BOOL contextOk = GetThreadContext(hThread, &context);
    >
    > STACKFRAME64 stackframe;
    > memset(&stackframe, 0, sizeof(STACKFRAME64));
    >
    > stackframe.AddrPC.Offset = context.Eip;
    > stackframe.AddrPC.Mode = AddrModeFlat;
    > stackframe.AddrFrame.Offset = context.Ebp;
    > stackframe.AddrFrame.Mode = AddrModeFlat;
    >
    > if(SymInitialize(hProcess, NULL, true))
    > {
    > int depth = 0;
    >
    > while( StackWalk64(IMAGE_FILE_MACHINE_I386,
    > hProcess,
    > hThread,
    > &stackframe,
    > &context,
    > NULL,
    > SymFunctionTableAccess64,
    > SymGetModuleBase64,
    > NULL))
    > {
    > if(stackframe.AddrPC.Offset!=0)
    > {
    > depth++;
    > }
    > }
    >
    > SymCleanup(hProcess);
    >
    > printf("Stack depth = %i\n", depth);
    > }
    > }
    >
    > void testAfter(int depth)
    > {
    > if(depth > 0)
    > {
    > depth--;
    > testAfter(depth);
    > }
    > else
    > {
    > stackTest();
    > }
    > }
    >
    > int main(int argc, char* argv[])
    > {
    > testAfter(100);
    > return 0;
    > }

  • Next message: hector: "Re: How to terminate a socket in CLOSE_WAIT state"