[danbruc]

If anyone is considering to use this, I think the code has a couple of concurrency bugs but I do not know if this was ever intended to be used in a multithreaded setting. vrb_get() contains the following code.

    //-- Limit request to available data.
    if ( arg_size > vrb_data_len( arg_vrb ) ) {
       arg_size = vrb_data_len( arg_vrb );
    }

    //-- If nothing to get, then just return now.
    if ( arg_size == 0 ) return 0;

    //-- Copy data to caller space.
    memcpy( arg_data, arg_vrb->first_ptr, arg_size );

If at the time of the check for the amount of available data there is less data available than requested but additional data gets added to the buffer before arg_size gets updated, then this might get more data than requested and overflow the target buffer. At least vrb_read() and vrb_write() have the same bug.

[defrost]

Sadly I can't ask the author anymore, I suspect this was a least feature possible stripped down port of a more battle tested cross platform library that dated to before the times of modern multi multi multi core chips.

Concurrency issues existed in the days of yore .. but they arose in different ways with different timings.

It's an odd bit of code archeology recalling a concept ( mmap ring buffers ) from decades past and then hunting to find the best remaining example - much of LibH was 'clean' rewrites of code from the authors past work.