The limit is space left on your hard drive up to the internal limitations of the system's ability to count in binary using a 64-bit word. That's about 17.5 TBs. But this is not a browser limit, it's a system imposed limit on the size for a single file. Of course for most people this far exceeds the storage capacity of any storage device except a multi-drive RAID striped array of at least six 3 TB hard drives.
Thanks Kappy, is that coming from internal developer knowledge, something documented by the Safari team, or imperical testing?
I assume Safari has to keep the filesize in some internal variable and just wanted to make sure they didn't artificially truncate it. Are their actually unit tests for Safari that have functionally tested this capability?
Thanks for further clarification.
Well, I claim no special insights. However, every OS has a counting limit set by the maximum word size it can handle. In a 64-bit system that amounts to 2^64 power which is about 17.5 TBs if my memory math is right (may not be 'cause I'm 70 and don't remember as well as I used to.) If my memory math is wrong then it may be more like 16,000,000 TBs. In any case it's really big!
File sizes are counted in blocks using a single word to count the number of blocks (usually.) So a computer that uses a 64-bit word can count as high as one 65-bit word can handle - 2^64. A 32-bit word counts to 4 GBs hence the 4 GB file size limit on older PC systems.
I'm sure somewhere someone may have tested this, but I don't know where you might find the information. I'm not a Safari expert so I don't know if Safari itself uses a smaller word-size to count file blocks. I've never downloaded anything much larger than 8 GBs or so. I have formatted, zeroed, and used 1 TB drives. Other users have 2 and 3 TB drives installed in Mac Pros.