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#### Primitive heap checking

The following listing contains the interface of the HeapMon unit.

This unit provide a rather primitive means to watch the heap, i.e. check if all pointers that were allocated are released again. This is meant as a debugging help for avoiding memory leaks.

More extensive heap checking is provided by libraries like `efence` which can be used in GPC programs without special provisions.

    { A unit to watch the heap, i.e. check if all pointers that were
      allocated are released again. It is meant as a debugging help to
      detect memory leaks.

      Use it in the main program before all other units. When, at the
      end of the program, some pointers that were allocated, have not
      been released, the unit writes a report to StdErr or another file
      (see below). Only pointers allocated via the Pascal mechanisms
      (New, GetMem) are tracked, not pointers allocated with direct libc
      calls or from C code. After a runtime error, pointers are not
      checked.

      Note that many units and libraries allocate memory for their own
      purposes and don't always release it at the end. Therefore, the
      usefulness of this unit is rather limited.

      Copyright (C) 1998-2003 Free Software Foundation, Inc.

      Author: Frank Heckenbach <frank@pascal.gnu.de>

      This file is part of GNU Pascal.

      GNU Pascal is free software; you can redistribute it and/or modify
      it under the terms of the GNU General Public License as published
      by the Free Software Foundation; either version 2, or (at your
      option) any later version.

      GNU Pascal is distributed in the hope that it will be useful, but
      WITHOUT ANY WARRANTY; without even the implied warranty of
      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
      General Public License for more details.

      You should have received a copy of the GNU General Public License
      along with GNU Pascal; see the file COPYING. If not, write to the
      Free Software Foundation, 59 Temple Place - Suite 330, Boston, MA
      02111-1307, USA.

      As a special exception, if you link this file with files compiled
      with a GNU compiler to produce an executable, this does not cause
      the resulting executable to be covered by the GNU General Public
      License. This exception does not however invalidate any other
      reasons why the executable file might be covered by the GNU
      General Public License. }

    {$gnu-pascal,I-}
    {$if __GPC_RELEASE__ < 20030303}
    {$error This unit requires GPC release 20030303 or newer.}
    {$endif}

    unit HeapMon;

    interface

    uses GPC;

    { This unit is automatically activated when used. The following
      declarations are only needed for special purposes. }

    { The report generated at the end can be redirected to a certain
      file by pointing HeapMonOutput to it. If not set, the report will
      be printed to the error messages file given with --gpc-rts
      options if given, and StdErr otherwise. }
    var
      HeapMonOutput: ^Text = nil;

    { HeapMonReport can be used to print a report on non-released memory
      blocks at an arbitrary point during a program run to the file f.
      It is invoked automatically at the end, so usually you don't have
      to call it. Returns True if any non-released blocks were found,
      False otherwise. }
    function HeapMonReport (var f: Text; DoRestoreTerminal: Boolean):
      Boolean; attribute (name = '_p_HeapMonReport');