mdb_preadfd() and mdb_pwritefd() Functions

size_t mdb_preadfd(void *handle, void *buf, size_t nbytes, off_t offset);
size_t mdb_pwritefd(void *handle, const void *buf, size_t nbytes, off_t offset);

The mdb_readfd() and mdb_writefd() functions take the opaque token passed from mdb_openfd() to read from and write to the specified file. Note that these functions use the same arguments as the pread() and pwrite() system calls.