Hello Mars,
the IPMC software does not support a full-fledged glibc library, it only implements a very reduced subset. Please remember that this code is running on a small microcontroller (Arm Cortex-M3) with a limited amount of memory, not a full-fledged desktop processor.
Below is the list of standard functions that are implemented (included in lib/lib.h), as you can see the ones you are trying to use are not there. However they are easy to implement in C if needed.
cheers,
Stefan