Yes I'm aware, but usually when I voice my gripes with integrating rsync somebody unfamiliar with the matter quickly googles 'rsync library', finds librsync, and assumes it must be the answer to my problem. Then I have to explain to them that it's not. I thought to head that off this time by mentioning upfront that librsync is not the answer.
Just to be sure I'm getting the question - you want to use rsync(1), and you're wondering if there's a good way to guard your code that's using/calling it from underlying changes in rsync options and output, how to read status/progress and such?
Here's an example of library that wraps rsync https://metacpan.org/pod/File::Rsync - you can provide callback functions that will be called for each line of stdout/stderr.
Granted it's in Perl - and chances are your code isn't written in Perl. So if you can't find something similar for your language of choice, and if you can't be bothered with checking out implementation in Perl and rewriting it...
And next to those - Perlito can "Compile Perl to Java/JavaScript/Python/Ruby/Go/etc" https://github.com/fglock/Perlito. I think we had/have some Perl code running in production Hadoop/JVM.
