The interface __getcwd_chk() shall function in the same way as the interface getcwd(), except that __getcwd_chk() shall check for buffer overflow before computing a result. If an overflow is anticipated, the function shall abort and the program calling it shall exit.
The parameter buflen specifies the size of the buffer buf. If len exceeds buflen, the function shall abort, and the program calling it shall exit.
The __getcwd_chk() function is not in the source standard; it is only in the binary standard.