_heapset(), _bheapset(), _fheapset(), _nheapset()

perform a consistency check on a heap

Synopsis:

#include <malloc.h>
int  _heapset( unsigned char fill_char );
int _bheapset( __segment seg, 
               unsigned char fill_char );
int _fheapset( unsigned char fill_char );
int _nheapset( unsigned char fill_char );

Description:

The _heapset() functions, along with _heapchk() and _heapwalk() are provided for debugging heap-related problems in programs.

The _heapset() functions perform a consistency check on the unallocated memory space or "heap", just as _heapchk() does, and sets the heap's free entries with the fill_char value.

Each function checks and sets a particular heap, as listed below:

_heapset(): Depends on data model of the program (see below)
_bheapset(): Based heap specified by seg value; _NULLSEG specifies all based heaps
_fheapset(): Far heap (outside the default data segment)
_nheapset(): Near heap (inside the default data segment)

In a small data memory model, _heapset() is equivalent to _nheapset(); in a large data memory model, _heapset() is equivalent to _fheapset().

Returns:

One of the following manifest constants, which are defined in <malloc.h>:

_HEAPOK: The heap appears to be consistent.
_HEAPEMPTY: The heap is empty.
_HEAPBADBEGIN: The heap has been damaged.
_HEAPBADNODE: The heap contains a bad node, or is damaged.

Examples:

#include <stdio.h>
#include <malloc.h>

void main()
  {
    int heap_status;
    char *buffer;

    buffer = (char *)malloc( 80 );
    malloc( 1024 );
    free( buffer );
    heap_status = _heapset( 0xff );
    switch( heap_status ) {
      case _HEAPOK:
        printf( "OK - heap is good\n" );
        break;
      case _HEAPEMPTY:
        printf( "OK - heap is empty\n" );
        break;
      case _HEAPBADBEGIN:
        printf( "ERROR - heap is damaged\n" );
        break;
      case _HEAPBADNODE:
        printf( "ERROR - bad node in heap\n" );
        break;
    }
  }

Classification:

WATCOM

Safety:
Interrupt handler	No
Signal handler	No
Thread	Yes