Category : C Source Code
Archive   : DMAKE38B.ZIP
Filename : MLC_CHN.C

 
Output of file : MLC_CHN.C contained in archive : DMAKE38B.ZIP
/*
* (c) Copyright 1990 Conor P. Cahill (uunet!virtech!cpcahil).
* You may copy, distribute, and use this software as long as this
* copyright statement is not removed.
*/
#include
#include
#include "malloc.h"

/*
* Function: malloc_chain_check()
*
* Purpose: to verify malloc chain is intact
*
* Arguments: todo - 0 - just check and return status
* 1 - call malloc_warn if error detected
*
* Returns: 0 - malloc chain intact & no overflows
* other - problems detected in malloc chain
*
* Narrative:
*
* Notes: If todo is non-zero the malloc_warn function, when called
* may not return (i.e. it may exit)
*
*/
#ifndef lint
static
char rcs_hdr[] = "$Id: mlc_chn.c,v 1.1 1992/01/24 03:29:10 dvadura Exp $";
#endif


int
malloc_chain_check(todo)
int todo;
{
char * func = "malloc_chain_check";
int i;
extern char * malloc_data_start;
extern char * malloc_data_end;
extern struct mlist * malloc_end;
extern int malloc_errno;
extern struct mlist malloc_start;
struct mlist * oldptr;
struct mlist * ptr;
int rtn = 0;

oldptr = &malloc_start;
for(ptr = malloc_start.next; ; ptr = ptr->next)
{
/*
* Since the malloc chain is a forward only chain, any
* pointer that we get should always be positioned in
* memory following the previous pointer. If this is not
* so, we must have a corrupted chain.
*/
if( ptr )
{
if(ptr < oldptr )
{
malloc_errno = M_CODE_CHAIN_BROKE;
if( todo )
{
malloc_fatal(func);
}
rtn++;
break;
}
oldptr = ptr;
}
else
{
if( oldptr != malloc_end )
{
/*
* This should never happen. If it does, then
* we got a real problem.
*/
malloc_errno = M_CODE_NO_END;
if( todo )
{
malloc_fatal(func);
}
rtn++;
}
break;
}

/*
* verify that ptr is within the malloc region...
* since we started within the malloc chain this should never
* happen.
*/

if( ((char *)ptr < malloc_data_start) ||
((char *)ptr > malloc_data_end) )
{
malloc_errno = M_CODE_BAD_PTR;
if( todo )
{
malloc_fatal(func);
}
rtn++;
break;
}

/*
* verify magic flag is set
*/

if( (ptr->flag&M_MAGIC) != M_MAGIC )
{
malloc_errno = M_CODE_BAD_MAGIC;
if( todo )
{
malloc_warning(func);
}
rtn++;
continue;
}

/*
* verify segments are correctly linked together
*/

if( (ptr->prev && (ptr->prev->next != ptr) ) ||
(ptr->next && (ptr->next->prev != ptr) ) ||
((ptr->next == NULL) && (ptr->prev == NULL)) )
{
malloc_errno = M_CODE_BAD_CONNECT;
if( todo )
{
malloc_warning(func);
}
rtn++;
continue;
}

/*
* If this segment is allocated
*/

if( (ptr->flag & M_INUSE) != 0 )
{
/*
* verify no overflow of data area
*/

for(i=ptr->r_size; i < ptr->s.size; i++)
{
if( ptr->data[i] != M_FILL )
{
malloc_errno = M_CODE_OVERRUN;
if( todo )
{
malloc_warning(func);
}
rtn++;
break;
}
}
}
else /* it's not allocated so */
{
/*
* verify no reuse of freed data blocks
*/

for(i=0; i < ptr->s.size; i++)
{
if( ptr->data[i] != M_FREE_FILL )
{
malloc_errno = M_CODE_REUSE;
if( todo )
{
malloc_warning(func);
}
rtn++;
break;
}
}
}

} /* for(... */

return(rtn);

} /* malloc_chain_check(... */


  3 Responses to “Category : C Source Code
Archive   : DMAKE38B.ZIP
Filename : MLC_CHN.C

  1. Very nice! Thank you for this wonderful archive. I wonder why I found it only now. Long live the BBS file archives!

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