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authorAndrew Yourtchenko <ayourtch@gmail.com>2019-03-28 20:36:56 +0100
committerDamjan Marion <dmarion@me.com>2019-04-02 06:54:43 +0000
commitd1a12ef820608516d6b9f76fe0e4ad8c7a04629c (patch)
treec25cf10827836a6ce6dbc074d5c644e602a7694f /src/vppinfra/sparse_vec.h
parenta4b10e5e86bac8464253beb14c1c57b120b57a09 (diff)
vppinfra: fix sparse_vec_index() returning non-zero index for some nonexistent elements
If we are testing for an index whose membership bitmask happens to sit in LSB of uword, and there is nothing else set in that uword in the member bitmask, the shortcut path returning the valid index is taken even if the element with a given index doesn't exist in the sparse vector. This happens because the count of leading zeroes on the value of 0 is zero, which is equal to the value taken modulo bitsize uword. Take care of that case. Also add unittests showing the problem and verifying that sparse_vec_index2 does not have the same issue. Change-Id: I19117e13817c3e5de579b9250bb741de42491985 Signed-off-by: Andrew Yourtchenko <ayourtch@gmail.com>
Diffstat (limited to 'src/vppinfra/sparse_vec.h')
-rw-r--r--src/vppinfra/sparse_vec.h4
1 files changed, 4 insertions, 0 deletions
diff --git a/src/vppinfra/sparse_vec.h b/src/vppinfra/sparse_vec.h
index cfa5778e290..54a92ce7a84 100644
--- a/src/vppinfra/sparse_vec.h
+++ b/src/vppinfra/sparse_vec.h
@@ -115,6 +115,10 @@ sparse_vec_index_internal (void *v,
w = h->is_member_bitmap[i];
+ /* count_trailing_zeros(0) == 0, take care of that case */
+ if (PREDICT_FALSE (maybe_range == 0 && insert == 0 && w == 0))
+ return 0;
+
if (PREDICT_TRUE (maybe_range == 0 && insert == 0 &&
count_trailing_zeros (w) == b))
return h->member_counts[i] + 1;