DefaultContext returns Context with no values set except a possibly nil fs.FS.

FdReader returns a valid reader for the given file descriptor or nil if syscall.EBADF.

FdWriter returns a valid writer for the given file descriptor or nil if syscall.EBADF.

NewContext is a factory function which helps avoid needing to know defaults or exporting all fields.

NewFSContext returns a mutable context if the fs is not EmptyFS.

EmptyFS is exported to special-case an empty file system.

Context holds module-scoped system resources currently only supported by built-in host functions.

FileEntry maps a path to an open file in a file system.

FSKey is a context.Context Value key.