In the implementation of the functions entropy and read_urandom you chose to call system function abort in case of failure to provide random data.

I don't know under which exact conditions a failure might happen. However, for a library I find it inappropriate to abort the process/application. The application should at least get a chance to handle this situation and to gracefully shut down the application. Yes, it is possible to implement a signal handler, but the library behaviour should be at least documented, so that a developer is aware of this.

Personally, I would prefer a solution where some sort of fallback function would be called in case the system function fails. For example, one could provide an own PRNG - yes, maybe slightly less secure, but certainly better than aborting the process. In addition, a warning message could be written to the log.