When tailing a container log, if the log file is empty it will cause the
log stream to abort with an unexpected `EOF`.
Note that this only applies to the "current" log file as rotated files
cannot be empty.
This fix just skips adding the "current" file the log tail if it is
empty.
Signed-off-by: Brian Goff <cpuguy83@gmail.com>
This allows much of the read logic to be shared for other things,
especially for the new log driver proposed in
https://github.com/moby/moby/issues/33475
The only logic for reads in the json logger is around decoding log
messages, which gets passed into the log file object.
This also helps with implementing compression as it allows us to
simplify locking strategies.
Signed-off-by: Brian Goff <cpuguy83@gmail.com>
