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  Object On The Stack
  Submitted by



isInStack(ptr) tests if an object pointed by ptr has been created to the stack or not. Motivation: When doing reference counting you want to assert you're not about to delete an object which has been allocated to the stack. Tested in following platforms:
  • MSVC6, Win2k
  • gcc 2.95.2, Win2k
  • gcc 2.95.2, Linux (RedHat)
  • gcc 2.8.1, Digital UNIX V4.0F


  • Makefile and MSVC6 project files are included.

    Known issues:
  • I haven't given any thought how this works in a shared library (dll/so)
  • Multithreading is supported only in Win32/MSVC


  • Jani Kajala PS. Why I didn't use !_CrtIsValidHeapPointer(p) of MSVCRT? 1) portability 2) coolness factor ;)


    Currently browsing [isInStack.zip] (3,545 bytes) - [isInStack.h] - (2,084 bytes)

    /*
     * isInStack 1.0
     * 
     * isInStack(ptr) tests if an object pointed by ptr
     * has been created to the stack or not.
     *
     * Motivation: When doing reference counting you 
     * want to assert you're not about to delete an object
     * which has been allocated to the stack.
     *
     * Tested in following platforms:
     * - MSVC6, Win2k
     * - gcc 2.95.2, Win2k
     * - gcc 2.95.2, Linux (RedHat)
     * - gcc 2.8.1, Digital UNIX V4.0F
     *
     * Makefile and MSVC6 project files are provided.
     *
     * Known issues:
     * - I haven't given any thought how this works in a shared library (dll/so)
     * - Multithreading is supported only in Win32/MSVC
     *
     * Feb 7, 2002,
     * Jani Kajala (jani.kajala@helsinki.fi)
     * 
     * PS.  Why I didn't use !_CrtIsValidHeapPointer(p) of MSVCRT?
     *      1) portability 2) coolness factor ;)
     */
    #ifndef _ISINSTACK_H
    #define _ISINSTACK_H

    /** * Initializes isInStack. * The init must be called in a higher level function than * where the isInitStack() is actually used. * * If multiple threads are used then the init needs to be called * at the beginning of each thread. Note that the thread function * calling isInStackInit must again be higher level than functions where * isInThread is actually used. */ void isInStackInit();

    /** * Returns true if the pointed object has been created in the stack * of the calling thread. */ bool isInStack( const void* p );

    /** Returns number of bytes of stack used by the calling thread. */ int usedStackSize();

    #endif // _ISINSTACK_H /* * Copyright (c) 2002 Jani Kajala * * Permission to use, copy, modify, distribute and sell this * software and its documentation for any purpose is hereby * granted without fee, provided that the above copyright notice * appear in all copies and that both that copyright notice and * this permission notice appear in supporting documentation. * Jani Kajala makes no representations about the suitability * of this software for any purpose. It is provided "as is" * without express or implied warranty. */

    Currently browsing [isInStack.zip] (3,545 bytes) - [isInStack.cpp] - (1,272 bytes)

    #include "isInStack.h"

    //------------------------------------------------------------------------ // thread local storage #ifdef _MSC_VER #define THREADLOCAL __declspec(thread) #else #define THREADLOCAL #endif

    //------------------------------------------------------------------------ /** Thread-specific stack bottom pointer. */ THREADLOCAL static const char* s_stackBottom = 0;

    //------------------------------------------------------------------------ static int getFrameSize( char* x ) { char y = 0; return x - &y; }

    void isInStackInit() { char x = 0; s_stackBottom = &x + getFrameSize(&x) * 2; }

    bool isInStack( const void* ptr ) { const char* p = (const char*)ptr; char x = 0; const char* stackTop = &x;

    if ( stackTop > s_stackBottom ) return p > s_stackBottom && p < stackTop; // stack grows up else return p > stackTop && p < s_stackBottom; // stack grows down }

    int usedStackSize() { char x = 0; const char* stackTop = &x;

    if ( stackTop > s_stackBottom ) return stackTop - s_stackBottom; // stack grows up else return s_stackBottom - stackTop; // stack grows down }

    Currently browsing [isInStack.zip] (3,545 bytes) - [test.cpp] - (1,042 bytes)

    #include "isInStack.h"
    #include <stdio.h>

    //------------------------------------------------------------------------ #define REQUIRE( A ) {if (!(A)) printf( "Assertion failed at %s(%i)\n", __FILE__, __LINE__ );}

    //------------------------------------------------------------------------ class MyClass { };

    //------------------------------------------------------------------------ static void func() { char testArray[123] = {0}; int size = usedStackSize(); printf( "usedStackSize in %s(%i) is %i\n", __FILE__, __LINE__, size );

    REQUIRE( isInStack(&size) ); REQUIRE( isInStack(testArray) ); }

    static void test() { char testArray[20] = {0}; MyClass a; MyClass* b = new MyClass; MyClass* c = new MyClass; MyClass d;

    func();

    REQUIRE( isInStack(&a) ); REQUIRE( !isInStack(b) ); REQUIRE( !isInStack(c) ); REQUIRE( isInStack(&d) );

    delete b; delete c; }

    int main() { isInStackInit(); test(); return 0; }

    The zip file viewer built into the Developer Toolbox made use of the zlib library, as well as the zlibdll source additions.

     

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