The interface __realpath_chk() shall function in the same way as the interface realpath(), except that __realpath_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 resolved_len specifies the size of the string
resolved_path. If resolved_len is less than
PATH_MAX, then the function shall abort, and the program calling it shall exit.
The __realpath_chk() function is not in the source standard; it is only in the binary standard.