I'm curious as to why i2clib_read et al has no documentation associated with it...

However, Digital.cpp (hal) claims:

@return Transfer Aborted... false for success, true for aborted.

So the question becomes: what is the real return value of i2clib_readwrite? I ran it through a disassembler, and it 
looks like the i2clib routines just call ioctl(), which could return anything, but that "Usually, on success zero is 
returned.  A few ioctl() requests use the return value as an output parameter and return a nonnegative value on success.
  On error, -1 is returned, and errno is set appropriately."