_heapchk, _bheapchk, _fheapchk, _nheapchk

perform a consistency check for a heap

Synopsis:

#include <malloc.h>
int  _heapchk( void );
int _bheapchk( __segment seg );
int _fheapchk( void );
int _nheapchk( void );

Description:

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

The _heapchk() functions perform a consistency check on the unallocated memory space or “heap”. The consistency check determines whether or not all the heap entries are valid. Each function checks a particular heap, as listed below:

_heapchk()

Depends on data model of the program (see below)

_bheapchk()

Based heap specified by seg value; _NULLSEG specifies all based heaps

_fheapchk()

Far heap (outside the default data segment)

_nheapchk()

Near heap (inside the default data segment)

In a small data memory model, the _heapchk() function is equivalent to the _nheapchk() function; in a large data memory model, the _heapchk() function is equivalent to the _fheapchk() function.

Returns:

All four functions return 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.

See also:

_heapenable(), _heapgrow(), _heapmin(), _heapset(), _heapshrink(), _heapwalk()

Examples:

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

void main()
  {
    char *buffer;

    buffer = (char *)malloc( 80 );
    malloc( 1024 );
    free( buffer );
    switch( _heapchk() ) {
    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

Systems:

_heapchk()

All (except Netware, DOS/PM)

_bheapchk()

DOS/16, Windows, QNX/16, OS/2 1.x(all)

_fheapchk()

DOS/16, Windows, QNX/16, OS/2 1.x(all)

_nheapchk()

DOS, Windows, Win386, Win32, QNX, OS/2 1.x, OS/2 1.x(MT), OS/2-32