Re: [PATCH] bisect: save heap memory. allocate only the required amount
- From
Jeff King <peff@peff.net>
- Date
- Aug 25, 2014, 13:35 UTC
- Message-ID
- <20140825133550.GE17288@peff.net>
- In-Reply-To
- <1408889844-5407-1-git-send-email-arjun024@gmail.com>
On Sun, Aug 24, 2014 at 07:47:24PM +0530, Arjun Sreedharan wrote:
Show 13 quoted lines
> diff --git a/bisect.c b/bisect.c
> index d6e851d..c96aab0 100644
> --- a/bisect.c
> +++ b/bisect.c
> @@ -215,10 +215,13 @@ static struct commit_list *best_bisection_sorted(struct commit_list *list, int n
> }
> qsort(array, cnt, sizeof(*array), compare_commit_dist);
> for (p = list, i = 0; i < cnt; i++) {
> - struct name_decoration *r = xmalloc(sizeof(*r) + 100);
> + char name[100];
> + sprintf(name, "dist=%d", array[i].distance);
> + int name_len = strlen(name);
> + struct name_decoration *r = xmalloc(sizeof(*r) + name_len);This allocation should be name_len + 1 for the NUL-terminator, no?
It looks like add_name_decoration in log-tree already handles half of what you are adding here. Can we just make that available globally (it is manipulating the already-global "struct decoration name_decoration")?
I also notice that we do not set r->type at all, meaning the decoration lookup code in log-tree will access uninitialized memory (worse, it will use it as a pointer offset into the color list; I got a segfault when I tried to run "git rev-list --bisect-all v1.8.0..v1.9.0").
I think we need this:
diff --git a/bisect.c b/bisect.c index d6e851d..e2a7682 100644 --- a/bisect.c +++ b/bisect.c @@ -219,6 +219,7 @@ static struct commit_list *best_bisection_sorted(struct commit_list *list, int n struct object *obj = &(array[i].commit->object); sprintf(r->name, "dist=%d", array[i].distance); + r->type = 0; r->next = add_decoration(&name_decoration, obj, r); p->item = array[i].commit; p = p->next; at a minimum. It looks like this was a regression caused by eb3005e (commit.h: add 'type' to struct name_decoration, 2010-06-19). Which makes me wonder if anybody actually _uses_ --bisect-all (which AFAICT is the only way to trigger the problem), but since it's public, I guess we should keep it. I think the sane thing here is to stop advertising name_decoration as a global, and make all callers use add_name_decoration. That makes it easier for callers like this one, and would have caught the regression caused be eb3005e (the compiler would have noticed that we were not passing a type parameter to the function). -Peff