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From: Ian Collins <ian-news@hotmail.com>
Newsgroups: comp.lang.c
Subject: Re: Malloc Query
Date: Sat, 21 May 2011 14:30:39 +1200
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Xref: x330-a1.tempe.blueboxinc.net comp.lang.c:4484

On 05/20/11 10:34 AM, Uncle Steve wrote:

A couple of comments on the code:

<snip>

> arena_head * arena_creat(size_t s, int n)
> {
>     arena_head * h;
>     int i;
>
>     h = malloc(sizeof(arena_head));
>     if(h == NULL) {
>        perror("malloc()");
>        exit(1);
>     }
>
>     h->obj_size = s;
>     h->arena_size = n;
>     h->free = n;
>
>     h->arena = malloc(s * n);
>     if(h->arena == NULL) {
>        perror("malloc()");
>        exit(1);
>     }
>
>     h->free_list = 0;
>
>     for(i = 0; i<  n; i++)
>        *((int *) arena_obj_addr(h, i)) = i + 1;
>
>     *((int *) arena_obj_addr(h, i)) = -1;

This writes past the end of the allocated block.

>     return(h);
> }
>
>
> typedef unsigned long long int T64;
>
> #define processcputime(p)                                                   \

Why go the the trouble of declaring this as a messy macro?

-- 
Ian Collins