> it's intuitively not strange for me to have a a zip that is carefully crafted so that memory and CPU goes out the window before any check can be done
It's intuitively extremely strange to me!
Even ignoring how zips work: Memory needs to be allocated in chunks. So before allocating a chunk, you can check if the new memory use will be over a threshold. CPU is used by the program instructions you control, so you can put checks at significant points in your program to see if it hit a threshold. Or you can have a thread you kill after a certain amount of time.
But the way zips do work makes it a lot simpler: Fundamentally it's "output X raw bytes, then repeat Y bytes from location Z" over and over. Abort if those numbers get too big.
It's intuitively extremely strange to me!
Even ignoring how zips work: Memory needs to be allocated in chunks. So before allocating a chunk, you can check if the new memory use will be over a threshold. CPU is used by the program instructions you control, so you can put checks at significant points in your program to see if it hit a threshold. Or you can have a thread you kill after a certain amount of time.
But the way zips do work makes it a lot simpler: Fundamentally it's "output X raw bytes, then repeat Y bytes from location Z" over and over. Abort if those numbers get too big.