SymGetLineFromAddr not working properly

Question

I have the following code:

#include "stdafx.h"
#include <process.h>
#include <iostream>
#include <Windows.h>
#include "dbghelp.h"

using namespace std;

int LogStackTrace()
{
    void *stack[1024];
    HANDLE process = GetCurrentProcess();
    SymInitialize(process, NULL, TRUE);
    WORD numberOfFrames = CaptureStackBackTrace(0, 1000, stack, NULL);
    SYMBOL_INFO *symbol = (SYMBOL_INFO *)malloc(sizeof(SYMBOL_INFO));
    symbol->MaxNameLen = 1024;
    symbol->SizeOfStruct = sizeof(SYMBOL_INFO);
    IMAGEHLP_LINE *line = (IMAGEHLP_LINE *)malloc(sizeof(IMAGEHLP_LINE));
    line->SizeOfStruct = sizeof(IMAGEHLP_LINE);
    printf("Caught exception ");
    for (int i = 0; i < numberOfFrames; i++)
    {
        SymFromAddr(process, (DWORD64)(stack[i]), NULL, symbol);
        SymGetLineFromAddr(process, (DWORD)(stack[i]), NULL, line);
        printf("at %s in %s, address 0x%0X\n", symbol->Name, line->FileName, symbol->Address);
    }
    return 0;
}

void function2()
{
    int a = 0;
    int b = 0;
    throw new exception("Expected exception.");
}

void function1()
{
    int a = 0;
    function2();
}

void function0()
{
    function1();
}

static void threadFunction(void *param)
{
    try
    {
        function0();
    }
    catch (...)
    {
        LogStackTrace();
    }
}

int _tmain(int argc, _TCHAR* argv[])
{
    try
    {
        _beginthread(threadFunction, 0, NULL);
    }
    catch (...)
    {
        LogStackTrace();
    }
    printf("Press any key to exit.\n");
    cin.get();
    return 0;
}

The problem is that it always errors out at this line: printf("at %s in %s, address 0x%0X\n", symbol->Name, line->FileName, symbol->Address);

The reason is because line's FileName seems to be NULL. Actually, the entire line structure is messed up. I am trying to write an application to show a stack trace on an error. But why is that? Shouldn't it be working using the above code? PS I compiled it against Win32, as a simple MSVC++ Console application.

Answer 1

Had the same problem with your code (Windows Seven 64b, Unicode 32 bits build, VS2012 Express)

Fixed it with :

DWORD dwDisplacement;
SymGetLineFromAddr(process, (DWORD)(stack[i]), &dwDisplacement, line);

Answer 2

SYMBOL_INFO *symbol = (SYMBOL_INFO *)malloc(sizeof(SYMBOL_INFO));
symbol->MaxNameLen = 1024;
symbol->SizeOfStruct = sizeof(SYMBOL_INFO);

The documentation for SizeOfStruct states:

The size of the structure, in bytes. This member must be set to sizeof(SYMBOL_INFO). Note that the total size of the data is the SizeOfStruct + (MaxNameLen - 1) * sizeof(TCHAR). The reason to subtract one is that the first character in the name is accounted for in the size of the structure.

Emphasis mine. You must allocate storage of at least sizeof(SYMBOL_INFO) + MaxNameLen + 1 bytes. You are only allocating sizeof(SYMBOL_INFO) bytes.