Re: [PATCH v2] merge-ort: only do pointer arithmetic for non-empty lists

From: Junio C Hamano <gitster@pobox.com>
Date: Apr 12, 2021, 17:39 UTC
Message-ID: <xmqqsg3ve711.fsf@gitster.g>
In-Reply-To: <CABPp-BE2D933Bc6w-OeaJc1r+1_tvMeK2M-HK4eEKPkQb3BdQQ@mail.gmail.com>

Elijah Newren <newren@gmail.com> writes:

> Otherwise, this patch looks good to me; thanks!

Queued, manually amended, and here is what I have.

$ git range-diff @{1}...
1:  ca4cc8d182 ! 1:  c1ea48a8f7 merge-ort: only do pointer arithmetic for non-empty lists
    @@ Commit message
         SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior merge-ort.c:2669:43 in
     
         Signed-off-by: Andrzej Hunt <ajrhunt@google.com>
    +    Reviewed-by: Elijah Newren <newren@gmail.com>
         Signed-off-by: Junio C Hamano <gitster@pobox.com>
     
      ## merge-ort.c ##
     @@ merge-ort.c: static void write_tree(struct object_id *result_oid,
    + 		       size_t hash_size)
    + {
      	size_t maxlen = 0, extra;
    - 	unsigned int nr = versions->nr - offset;
    +-	unsigned int nr = versions->nr - offset;
    ++	unsigned int nr;
      	struct strbuf buf = STRBUF_INIT;
     -	struct string_list relevant_entries = STRING_LIST_INIT_NODUP;
      	int i;
    @@ merge-ort.c: static void write_tree(struct object_id *result_oid,
     -	relevant_entries.nr = versions->nr - offset;
     -	QSORT(relevant_entries.items, relevant_entries.nr, tree_entry_order);
     +	assert(offset <= versions->nr);
    ++	nr = versions->nr - offset;
     +	if (versions->nr)
     +		QSORT(versions->items + offset, nr, tree_entry_order);