fix: Fix reading of files larger than 2^31 bytes

fix: Fix reading of files larger than 2^31 bytes

For some kernels read(2) makes a short read for counts larger than 2^31,
even for files on 64-bit architectures. Other kernels seem to not like
large counts at all, returning a failure.

Fix this by limiting the read buffer to a smaller value. This also
removes a short read optimization which should have been removed in
cff3bf417420ea88fe53e7267ae2a356898ae326.