A block of mutable bytes. Lua strings are immutable, so anything that holds a lot of data and changes it has to allocate a new copy every time — fine for a few kilobytes, ruinous for megabytes arriving sixty times a second. A Buffer is a fixed-size array you write into and overwrite in place. It is deliberately primitive: a size, a read, a write, a fill. No growth, no types, no structure — whatever a mod wants to keep in it is the mod's business.
Offsets are 0-based throughout, to match Frame. Every access is bounds-checked: a read past the end is short, a write past the end is dropped.
A buffer of n zeroed bytes. Returns nil if that much memory isn't available rather than raising — asking for more than the machine has is a normal thing for a mod sizing itself to a user's settings to do, and it needs to be able to back off instead of dying.
How many bytes it holds. Fixed for the buffer's life. Takes no parameters.
Copies len bytes out as a string, from 0-based offset from. Clamped to the end of the buffer, so a request that runs off it returns what exists.
Writes the string src at 0-based offset at. Returns how many bytes were written — less than #src if it hit the end.
Sets every byte to v (0–255).
data.append take (name, buf, from, len) as well as a string, so a slice goes to the file without being copied through Lua first.