The data structures linkhash and printbuf are limited to 2 GB in size
due to a signed integer being used to track their current size.
If too much data is added, then size variable can overflow, which is
an undefined behaviour in C programming language.
Assuming that a signed int overflow just leads to a negative value,
like it happens on many sytems (Linux i686/amd64 with gcc), then
printbuf is vulnerable to an out of boundary write on 64 bit systems.
If a linkhash with a size of zero is created, then modulo operations
are prone to division by zero operations.
Purely protective measure against bad usage.
If the assignment of stop overflows due to idx and count being
larger than SIZE_T_MAX in sum, out of boundary access could happen.
It takes invalid usage of this function for this to happen, but
I decided to add this check so array_list_del_idx is as safe against
bad usage as the other arraylist functions.
Tobias Stoeckmann