如何知道堆结束的地址？

Question

Thanks for the replies and answers. This question was edited because it seems my whole previous questions were very blur and doesn't give the exact details of what I want to achieve and my goal.

Using C language in Linux platform, what possible ways to determine the size of the heap used in my application. Like for example..

void printHeapReport( )
{
   /* implementation here to print the heap size */
}

int main()
{
    char *ptemp = NULL;
    p = (char*)malloc( 10 ); /* 10 bytes */

    printHeapReport();

    return 0;
}

The application will output in the standard output screen:

Debug Report:  
--------------  
Heap: 10 bytes  
--------------  

I ask this because I want to create a debug report in application that will print the size of the heap.

Please advice.

Many thanks.

---

Old Question:

Using C asm inline function, is it possible to know the address of the start of the heap and the end of the heap? Also the address of the end of the program?

asm( <assembly code> );

So that using this code I can determine the size of the heap used in my application. Is this approach is valid to determine the size of the heap?

Please advice.

Many thanks.

Answer 1

You would have to at least specify what platform you're dealing with, and realize on many platforms the question doesn't really have an answer. The 'heap' doesn't need to be contiguous - in many cases there will be several heaps for different types of objects (like for certain sized requests), and the runtime might acquire blocks for the 'heap' as needed from the underlying OS.

Similarly for the 'program' - various parts of the executable might be interspersed with data, or regions of address space that have nothing in them.

Answer 2

Assembly is utterly useless for this. If your system's implementation of the standard library exposes a variable that stores the address of the top of the heap, you can access it just as easily without asm. Otherwise, you might be able to access and process OS-specific process data, for instance (on Linux) /proc/self/smaps , to determine your program's address layout. But regardless, asm will not help you .

Answer 3

If your standard library is glibc (likely), then you can #include <malloc.h> and call malloc_stats(); to print a heap report to stderr .