Increase allocated memory for timestamp index

[ShangzhiXu]

Further fix #792

[minminlittleshrimp]

Hi @ShangzhiXu
v3. has been released and we now back to normal maintaining phase, is this patch checked/validated your side? how this fix the issue, can you explain a bit further why 1->2 can fix?

[ShangzhiXu]

cheers~ let me double check~

[ShangzhiXu]

Hi there, sorry for the late reply, I've double checked and this bug is still reproducable on the current version, and the patch works on my side.

It is actually that a off-by-one occurs due to some logic error,

    message_count = (uint32_t) (1 + end - begin); // lets assume message_count = a

    timestamp_index = (TimestampIndex *) malloc(sizeof(TimestampIndex) * (message_count + 1)); // alloc: a + 1 
    ...
    timestamp_index[message_count + 1].num = timestamp_index[0].num; // visit timestamp_index[a + 1]

Here we write timestamp_index[a + 1], but the array has only a + 1 elements, so the valid indices are [0 .. a].
This fix locates message_count + 2 elements to make the valid index range [0 .. a + 1]