/*
 * Standard debugging hooks for `malloc'.
 * * Copyright 1990, 1991, 1992, 1993, 1994 Free Software Foundation, Inc.
 * * Written May 1989 by Mike Haertel.
 * * 
 * * This library is free software; you can redistribute it and/or
 * * modify it under the terms of the GNU Library General Public License as
 * * published by the Free Software Foundation; either version 2 of the
 * * License, or (at your option) any later version.
 * * 
 * * This library 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
 * * Library General Public License for more details.
 * * 
 * * You should have received a copy of the GNU Library General Public
 * * License along with this library; see the file COPYING.LIB.  If
 * * not, write to the Free Software Foundation, Inc., 675 Mass Ave,
 * * Cambridge, MA 02139, USA.
 * * 
 * * The author may be reached (Email) at the address mike@ai.mit.edu,
 * * or (US mail) as Mike Haertel c/o Free Software Foundation.  
 */

#ifndef	_MALLOC_INTERNAL
#define	_MALLOC_INTERNAL
#include <stdio.h>
#endif

#include "copyright.h"
#include "autoconf.h"
#include "externs.h"
#include "malloc.h"

/*
 * Old hook values.  
 */
static void (*old_free_hook) __P((__ptr_t ptr));
static __ptr_t(*old_malloc_hook) __P((__malloc_size_t size));
static __ptr_t(*old_realloc_hook) __P((__ptr_t ptr, __malloc_size_t size));

/*
 * Function to call when something awful happens.  
 */
static void (*abortfunc) __P((enum mcheck_status));

/*
 * Arbitrary magical numbers.  
 */
#define MAGICWORD	0xfedabeeb
#define MAGICFREE	0xd8675309
#define MAGICBYTE	((char) 0xd7)
#define MALLOCFLOOD	((char) 0x93)
#define FREEFLOOD	((char) 0x95)

struct hdr {
	__malloc_size_t size;	/*
				 * Exact size requested by user.  
				 */
	unsigned long int magic;	/*
					 * Magic number to check header * *
					 * integrity.  
					 */
};

#if	defined(_LIBC) || defined(STDC_HEADERS) || defined(USG)
#define flood memset
#else
static void flood __P((__ptr_t, int, __malloc_size_t));
static void flood(ptr, val, size)
__ptr_t ptr;
int val;
__malloc_size_t size;
{
	char *cp = ptr;

	while (size--)
		*cp++ = val;
}
#endif

static enum mcheck_status checkhdr __P((const struct hdr *));
static enum mcheck_status checkhdr(hdr)
const struct hdr *hdr;
{
	enum mcheck_status status;

	switch (hdr->magic) {
	default:
		status = MCHECK_HEAD;
		break;
	case MAGICFREE:
		status = MCHECK_FREE;
		break;
	case MAGICWORD:
		if (((char *)&hdr[1])[hdr->size] != MAGICBYTE)
			status = MCHECK_TAIL;
		else
			status = MCHECK_OK;
		break;
	}
	if (status != MCHECK_OK)
		(*abortfunc) (status);
	return status;
}

static void freehook __P((__ptr_t));
static void freehook(ptr)
__ptr_t ptr;
{
	struct hdr *hdr = ((struct hdr *)ptr) - 1;

	checkhdr(hdr);
	hdr->magic = MAGICFREE;
	flood(ptr, FREEFLOOD, hdr->size);
	__free_hook = old_free_hook;
	free(hdr);
	__free_hook = freehook;
}

static __ptr_t mallochook __P((__malloc_size_t));
static __ptr_t
 mallochook(size)
__malloc_size_t size;
{
	struct hdr *hdr;

	__malloc_hook = old_malloc_hook;
	hdr = (struct hdr *)malloc(sizeof(struct hdr) + size + 1);

	__malloc_hook = mallochook;
	if (hdr == NULL)
		return NULL;

	hdr->size = size;
	hdr->magic = MAGICWORD;
	((char *)&hdr[1])[size] = MAGICBYTE;
	flood((__ptr_t) (hdr + 1), MALLOCFLOOD, size);
	return (__ptr_t) (hdr + 1);
}

static __ptr_t reallochook __P((__ptr_t, __malloc_size_t));
static __ptr_t
 reallochook(ptr, size)
__ptr_t ptr;
__malloc_size_t size;
{
	struct hdr *hdr = ((struct hdr *)ptr) - 1;
	__malloc_size_t osize = hdr->size;

	checkhdr(hdr);
	if (size < osize)
		flood((char *)ptr + size, FREEFLOOD, osize - size);
	__free_hook = old_free_hook;
	__malloc_hook = old_malloc_hook;
	__realloc_hook = old_realloc_hook;
	hdr = (struct hdr *)realloc((__ptr_t) hdr, sizeof(struct hdr) + size + 1);

	__free_hook = freehook;
	__malloc_hook = mallochook;
	__realloc_hook = reallochook;
	if (hdr == NULL)
		return NULL;

	hdr->size = size;
	hdr->magic = MAGICWORD;
	((char *)&hdr[1])[size] = MAGICBYTE;
	if (size > osize)
		flood((char *)(hdr + 1) + osize, MALLOCFLOOD, size - osize);
	return (__ptr_t) (hdr + 1);
}

static void mabort(status)
enum mcheck_status status;
{
	const char *msg;

	switch (status) {
	case MCHECK_OK:
		msg = "memory is consistent, library is buggy";
		break;
	case MCHECK_HEAD:
		msg = "memory clobbered before allocated block";
		break;
	case MCHECK_TAIL:
		msg = "memory clobbered past end of allocated block";
		break;
	case MCHECK_FREE:
		msg = "block freed twice";
		break;
	default:
		msg = "bogus mcheck_status, library is buggy";
		break;
	}

	STARTLOG(LOG_ALWAYS, "BUG", "MLLOC")
		log_text(tprintf("mcheck: %s\n", msg));
	ENDLOG
}

static int mcheck_used = 0;

int mcheck(void)
{
	abortfunc = &mabort;

	/*
	 * These hooks may not be safely inserted if malloc is already in * * 
	 * use.  
	 */
	if (!__malloc_initialized && !mcheck_used) {
		old_free_hook = __free_hook;
		__free_hook = freehook;
		old_malloc_hook = __malloc_hook;
		__malloc_hook = mallochook;
		old_realloc_hook = __realloc_hook;
		__realloc_hook = reallochook;
		mcheck_used = 1;
	}
	return mcheck_used ? 0 : -1;
}

enum mcheck_status mprobe(__ptr_t ptr)
{
	return mcheck_used ? checkhdr(ptr) : MCHECK_DISABLED;
}