/* More debugging hooks for `malloc'.
   Copyright 1991 Free Software Foundation
		  Written April 2, 1991 by John Gilmore of Cygnus Support
		  Based on mcheck.c by Mike Haertel.

This program 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 of the License, or
(at your option) any later version.

This program 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 this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  */

/* IGNORE(@ */
#include <ansidecl.h>
#include <stdlib.h>
/* @) */

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

#ifndef	__GNU_LIBRARY__
extern char *getenv ();
#endif

static FILE *mallstream;
static char mallenv[] = "MALLOC_TRACE";
static char mallbuf[BUFSIZ];	/* Buffer for the output.  */

/* Address to breakpoint on accesses to... */
PTR mallwatch;

/* Old hook values.  */
static void EXFUN((*old_free_hook), (PTR ptr));
static PTR EXFUN((*old_malloc_hook), (size_t size));
static PTR EXFUN((*old_realloc_hook), (PTR ptr, size_t size));

/* This function is called when the block being alloc'd, realloc'd, or
   freed has an address matching the variable "mallwatch".  In a debugger,
   set "mallwatch" to the address of interest, then put a breakpoint on
   tr_break.  */

void
DEFUN_VOID(tr_break)
{
}

static void
DEFUN(tr_freehook, (ptr), PTR ptr)
{
  fprintf(mallstream, "- %p\n", ptr);	/* Be sure to print it first.  */
  if (ptr == mallwatch)
    tr_break ();
  __free_hook = old_free_hook;
  free (ptr);
  __free_hook = tr_freehook;
}

static PTR
DEFUN(tr_mallochook, (size), size_t size)
{
  PTR hdr;

  __malloc_hook = old_malloc_hook;
  hdr = (PTR) malloc (size);
  __malloc_hook = tr_mallochook;

  /* We could be printing a NULL here; that's OK.  */
  fprintf (mallstream, "+ %p %x\n", hdr, size);

  if (hdr == mallwatch)
    tr_break ();

  return hdr;
}

static PTR
DEFUN(tr_reallochook, (ptr, size), PTR ptr AND size_t size)
{
  PTR hdr;

  if (ptr == mallwatch)
    tr_break ();

  __free_hook = old_free_hook;
  __malloc_hook = old_malloc_hook;
  __realloc_hook = old_realloc_hook;
  hdr = (PTR) realloc (ptr, size);
  __free_hook = tr_freehook;
  __malloc_hook = tr_mallochook;
  __realloc_hook = tr_reallochook;
  if (hdr == NULL)
    /* Failed realloc.  */
    fprintf (mallstream, "! %p %x\n", ptr, size);
  else
    fprintf (mallstream, "< %p\n> %p %x\n", ptr, hdr, size);

  if (hdr == mallwatch)
    tr_break ();

  return hdr;
}

/* We enable tracing if either the environment variable MALLOC_TRACE
   is set, or if the variable mallwatch has been patched to an address
   that the debugging user wants us to stop on.  When patching mallwatch,
   don't forget to set a breakpoint on tr_break!  */

void
DEFUN_VOID(mtrace)
{
  char *mallfile;
  
  mallfile = getenv (mallenv);
  if (mallfile  != NULL || mallwatch != NULL)
    {
      mallstream = fopen (mallfile != NULL ? mallfile : "/dev/null", "w");
      if (mallstream != NULL)
	{
	  /* Be sure it doesn't malloc its buffer!  */
	  setbuf (mallstream, mallbuf);
	  fprintf (mallstream, "= Start\n");
	  old_free_hook = __free_hook;
	  __free_hook = tr_freehook;
	  old_malloc_hook = __malloc_hook;
	  __malloc_hook = tr_mallochook;
	  old_realloc_hook = __realloc_hook;
	  __realloc_hook = tr_reallochook;
	}
    }
}