pread64() shall read count bytes into buf from the file associated with the open file descriptor fd, at the position specified by offset, without changing the file position.
pread64() is a large-file version of the pread() function as defined in POSIX 1003.1-2001 (ISO/IEC 9945-2003). It differs from pread() in that the offset parameter is an off64_t instead of an off_t
On success, pread64() shall return the number
of bytes actually read. Otherwise pread64()
shall return -1 and
errno to indicate the error.