diff options
| -rw-r--r-- | passlib/utils/__init__.py | 10 |
1 files changed, 6 insertions, 4 deletions
diff --git a/passlib/utils/__init__.py b/passlib/utils/__init__.py index bc035fc..a08cacb 100644 --- a/passlib/utils/__init__.py +++ b/passlib/utils/__init__.py @@ -495,13 +495,15 @@ def consteq(left, right): raise TypeError("inputs must be both unicode or bytes") # do size comparison. - # XXX: this does one extra branch instruction when the string lengths don't - # match, compared to when they do. would be nice to equalize the cases. - if len(left) == len(right): + # NOTE: the double-if construction below is done deliberately, to ensure + # the same number of operations (including branches) is performed regardless + # of whether left & right are the same size. + same = (len(left) == len(right)) + if same: # if sizes are the same, setup loop to perform actual check of contents. tmp = left result = 0 - else: + if not same: # if sizes aren't the same, set 'result' so equality will fail regardless # of contents. then, to ensure we do exactly 'len(right)' iterations # of the loop, just compare 'right' against itself. |