CODEWITHSUNDEEP
c++callstack
szx
szx

Reputation: 6946

How to determine end of call stack?

So I wrote two simple classes - X86StackFrame and X86CallStack:

class X86StackFrame {
public:
    X86StackFrame(void *frmAddr, void *retAddr);

    inline void *GetFrameAddress() const 
        { return frmAddr_; }
    inline void *GetReturnAddress() const 
        { return retAddr_; }

private:
    void *frmAddr_;
    void *retAddr_;
};

class X86CallStack {
public:
    X86CallStack();

    inline std::deque<X86StackFrame> GetFrames() const {
        return frames_;
    }

private:
    std::deque<X86StackFrame> frames_;
};

The key method here is X86CallStack's ctor:

static inline void *GetReturnAddress(void *frmAddr) {
    return *reinterpret_cast<void**>(reinterpret_cast<char*>(frmAddr) + 4);
}

static inline void *GetNextFrame(void *frmAddr) {
    return *reinterpret_cast<void**>(frmAddr);
}

X86CallStack::X86CallStack()
    : frames_()
{
    void *frmAddr;
    void *retAddr;

    #if defined _MSC_VER
        __asm mov dword ptr [frmAddr], ebp
    #elif defined __GNUC__
        __asm__ __volatile__(
            "movl %%ebp, %0;" : "=r"(frmAddr) : : );
    #endif  

    do {
        if (frmAddr == 0) {
            break;
        }
        retAddr = GetReturnAddress(frmAddr);
        if (retAddr == 0) {
            break;
        }
        frmAddr = GetNextFrame(frmAddr);
        frames_.push_back(X86StackFrame(frmAddr, retAddr));
    } while (true);
}

And the problem is... how do I end that loop? I mean, checking frame/return address against 0 sometimes does the trick but not always (at least here on Windows).

Any suggestions?

Upvotes: 3

Views: 245

Answers (1)

user1233508
user1233508

Reputation:

On Windows, reading the Thread Information Block can give you the top and bottom of the stack so you can stop before reading anything beyond that range. I have no idea how to get similar info on other OSes, though.

Upvotes: 3

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