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From: ferneau@silver.UUCP
Newsgroups: comp.unix.wizards
Subject: Ultrix-2.0 calloc bug?
Message-ID: <12300001@silver>
Date: Fri, 2-Oct-87 05:23:00 EDT
Article-I.D.: silver.12300001
Posted: Fri Oct  2 05:23:00 1987
Date-Received: Sat, 3-Oct-87 10:11:52 EDT
Organization: Indiana University BACS, Bloomington
Lines: 97
Nf-ID: #N:silver:12300001:000:1967
Nf-From: silver.bacs.indiana.edu!ferneau    Oct  2 04:23:00 1987


/* Written  4:19 am  Oct  2, 1987 by ferneau@silver.UUCP in silver:cs.unix.bacs */
/* ---------- "Ultrix-2.0 calloc bug?" ---------- */
I am having a problem with dynamic memory allocation on silver (a
VAX 8650 running Ultrix 2.0) using the calloc() routine, which seems
to be corrupting my array.

Here is the program I am using:

/*
 * tmp.c
 * 
 * copy a given argument list into dynamic memory
 *
 */

#include <stdio.h>
#include <memory.h>

#define ERR stderr

char    **replicate();
char *Me;

main(argC,argV)
int argC;
char **argV;
{
  int argc;
  char **argv;
  int x;

  Me = *argV;
  argc = argC;

  argv = replicate(argC,argV);
  for (x=0; x<argc; x++)
    fprintf(ERR,"av[%u] = %s\n", x, argv[x]);
}


char **
replicate(ac,av)
int ac;
char **av;
{
  char **nav;
  int x;
  
  if ((nav = (char **) calloc(ac,sizeof(char *)))==NULL) {
    fprintf(ERR,"%s: out of memory\n", Me);
    exit(1);
  }

  for (x=0; x<ac; x++) {
    if ((nav[x]=(char *)calloc(sizeof(av[x])+1,1))==NULL) {
      fprintf(ERR,"%s: out of memory\n", Me);
      exit(1);
    }
    if (x)
      fprintf(ERR,"av[%u] = %s\n", x-1, nav[x-1]);
    fprintf(ERR,"av[%u] = %s\n", x, nav[x]);
    strcpy(nav[x],av[x]);
    fprintf(ERR,"av[%u] = %s\n", x, nav[x]);
  }

  return(nav);
}
    
----------------------------------------------------------
End of Program
----------------------------------------------------------

I type "tmp 123456789012345678901234567890 argument" to the shell, and
this is what I get back:

av[0] = 
av[0] = tmp
av[0] = tmp
av[1] = 
av[1] = 123456789012345678901234567890
av[1] = 12345678901256
av[2] = 
av[2] = argument
av[0] = tmp
av[1] = 12345678901256argument
av[2] = argument


You will notice that av[1] is corrupted only after a call to calloc (see
the code in _replicate()_. I assume that this is a problem in the
c-library. I would appreciate any help anyone could give.

ferneau@silver.bacs.indiana.edu

.
/* End of text from silver:cs.unix.bacs */