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[BITARRAY] Bounds check in the first iteration in bitArrayFindFirstSet() (#5707)

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We already had bounds checking for the 2nd and subsequent 32 bit
blocks, but since the first block was handled separately (due to the
masking needed if it doesn't fall on a 32 bit boundary) it skipped
the check. With this change, any start bit >= the number of bits
in the array will return -1.
This commit is contained in:
Alberto García Hierro 2020-05-16 16:38:31 +01:00 • committed by GitHub
parent 3cbf830e04
commit 7f1a7d5a0b
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GPG key ID: 4AEE18F83AFDEB23
2 changed files with 21 additions and 8 deletions
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18
src/main/common/bitarray.c
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@ -75,17 +75,19 @@ int bitArrayFindFirstSet(const bitarrayElement_t *array, unsigned start, size_t
const uint32_t *end = ptr + (size / 4); const uint32_t *end = ptr + (size / 4);
const uint32_t *p = ptr + start / (8 * 4); const uint32_t *p = ptr + start / (8 * 4);
int ret; int ret;
// First iteration might need to mask some bits if (p < end) {
uint32_t mask = 0xFFFFFFFF << (start % (8 * 4)); // First iteration might need to mask some bits
if ((ret = __CTZ(*p & mask)) != 32) { uint32_t mask = 0xFFFFFFFF << (start % (8 * 4));
return (((char *)p) - ((char *)ptr)) * 8 + ret; if ((ret = __CTZ(*p & mask)) != 32) {
}
p++;
while (p < end) {
if ((ret = __CTZ(*p)) != 32) {
return (((char *)p) - ((char *)ptr)) * 8 + ret; return (((char *)p) - ((char *)ptr)) * 8 + ret;
} }
p++; p++;
while (p < end) {
if ((ret = __CTZ(*p)) != 32) {
return (((char *)p) - ((char *)ptr)) * 8 + ret;
}
p++;
}
} }
return -1; return -1;
} }

11
src/test/unit/bitarray_unittest.cc
View file

@ -83,3 +83,14 @@ TEST(BitArrayTest, TestSetClrAll)
EXPECT_EQ(ii, BITARRAY_FIND_FIRST_SET(p, ii)); EXPECT_EQ(ii, BITARRAY_FIND_FIRST_SET(p, ii));
} }
} }
TEST(BitArrayTest, TestOutOfBounds)
{
const int bits = 32 * 4;
BITARRAY_DECLARE(p, bits);
BITARRAY_CLR_ALL(p);
EXPECT_EQ(-1, BITARRAY_FIND_FIRST_SET(p, 0));
EXPECT_EQ(-1, BITARRAY_FIND_FIRST_SET(p, bits));
EXPECT_EQ(-1, BITARRAY_FIND_FIRST_SET(p, bits + 1));
}