Handle case when read actually reads less data than the user requested

[JackKelly]

The manual for read says:

On success, the number of bytes read is returned (zero indicates
end of file), and the file position is advanced by this number.
It is not an error if this number is smaller than the number of
bytes requested; this may happen for example because fewer bytes
are actually available right now (maybe because we were close to
end-of-file, or because we are reading from a pipe, or from a
terminal), or because read() was interrupted by a signal. See
also NOTES.

I guess we submit a new read operation, to get the remaining bytes? But don't retry forever!

Related

• Ensure that the read operation reads the correct number of bytes #97
• Splits reads of more than 2 GiBytes into multiple reads #99