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hllSparseAdd() sanity check for span != 0 added.

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antirez 2014-04-13 10:19:12 +02:00
parent 80140fa006
commit 2067644a8c
1 changed files with 3 additions and 0 deletions
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3
src/hyperloglog.c
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@ -612,6 +612,7 @@ sds hllSparseToDense(sds sparse) {
*
* On success, the function returns 1 if the cardinality changed, or 0
* if the register for this element was not updated.
* On error (if the representation is invalid) -1 is returned.
*
* As a side effect the function may promote the HLL representation from
* sparse to dense: this happens when a register requires to be set to a value
@ -645,6 +646,7 @@ int hllSparseAdd(robj *o, unsigned char *ele, size_t elesize) {
first = 0;
prev = NULL; /* Points to previos opcode at the end of the loop. */
next = NULL; /* Points to the next opcode at the end of the loop. */
span = 0;
while(p < end) {
/* Set span to the number of registers covered by this opcode. */
if (HLL_SPARSE_IS_ZERO(p)) span = HLL_SPARSE_ZERO_LEN(p);
@ -656,6 +658,7 @@ int hllSparseAdd(robj *o, unsigned char *ele, size_t elesize) {
p += (HLL_SPARSE_IS_XZERO(p)) ? 2 : 1;
first += span;
}
if (span == 0) return -1; /* Invalid format. */
next = HLL_SPARSE_IS_XZERO(p) ? p+2 : p+1;
if (next >= end) next = NULL;