> Which basically expanded back in the day to 65k reads of 1 byte for several MB file. Each fread translated to 65k reads of ReadFile Windows API
What software did that that badly? If the code asks for (up to) 65,536 single byte items, why would you split that into 65,536 calls?
Also, that change changes behavior. The old call could read anything from zero to 65,536 bytes, the new one only can read zero or 65,536 bytes.
(Reading the source of a few implementations, I think most implementations will fill the output buffer with partial objects if the input doesn’t supply an integral number of them, but the return value of fread cannot signal that to the caller)
I assumed it was a simple mistake: easy to forget what order the two integers are sent.
A long time ago I worked with someone who read 1 byte at a time from a socket because they insisted data was cached so the kernel was going to batch it magically somehow. It took me days to convince them to measure it.