_heapchk -- Validate Default Memory Heap

Format

#include <malloc.h>
int _heapchk(void);

Language Level: Extension
_heapchk checks the default storage heap for minimal consistency by checking all allocated and freed objects on the heap.

A heap-specific version of this function, _uheapchk, is also available.

Note: Using the _heapchk, _heapset, and _heap_walk functions (and their heap-specific equivalents) may add overhead to each object allocated from the heap.

Return Value
_heapchk returns one of the following values, defined in <malloc.h>:

_HEAPBADBEGIN The heap specified is not valid. (Only occurs if you changed the default heap and then later closed or destroyed it.)
_HEAPBADNODE A memory node is corrupted, or the heap is damaged.
_HEAPEMPTY The heap has not been initialized.
_HEAPOK The heap appears to be consistent.

Example
This example performs some memory allocations, then calls _heapchk to check the heap.

#include <stdlib.h>
#include <stdio.h>
#include <malloc.h>
int main(void)
{
   char *ptr;
   int  rc;
   if (NULL == (ptr = (char*)malloc(10))) {
      puts("Could not allocate memory block.");
      exit(EXIT_FAILURE);
   }
   *(ptr - 1) = 'x';      /* overwrites storage that was not allocated */
   if (_HEAPOK != (rc = _heapchk())) {
      switch(rc) {
         case _HEAPEMPTY:
            puts("The heap has not been initialized.");
            break;
         case _HEAPBADNODE:
            puts("A memory node is corrupted or the heap is damaged.");
            break;
         case _HEAPBADBEGIN:
            puts("The heap specified is not valid.");
            break;
      }
      exit(rc);
   }
   free(ptr);
   return 0;
   /****************************************************************
      The output should be similar to:
      A memory node is corrupted or the heap is damaged.
   ****************************************************************/
}



Memory Management


_debug_heapmin -- Release Unused Memory in the Default Heap
_heapmin -- Release Unused Memory from Default Heap
_heapset -- Validate and Set Default Heap
_heap_walk -- Return Information about Default Heap
<malloc.h>
<stdlib.h>