diffcore-break: don't divide by zero

When the source file is empty, the calculation of the merge score
results in a division by zero.  In the situation:

     == preimage ==             == postimage ==

     F (empty file)             F (a large file)
                                E (a new empty file)

it does not make sense to consider F->E as a rename, so it is better not
to break the pre- and post-image of F.

Bail out early in this case to avoid hitting the divide-by-zero.  This
causes the merge score to be left at zero.

Signed-off-by: John Keeping <john@keeping.me.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
John Keeping 2013-04-03 20:24:05 +01:00 committed by Junio C Hamano
parent 15999998fb
commit e7b00c5764

View File

@ -68,6 +68,9 @@ static int should_break(struct diff_filespec *src,
if (max_size < MINIMUM_BREAK_SIZE)
return 0; /* we do not break too small filepair */
if (!src->size)
return 0; /* we do not let empty files get renamed */
if (diffcore_count_changes(src, dst,
&src->cnt_data, &dst->cnt_data,
0,