--- regular file ---
readv(file, NULL, 0) [expect EINVAL]                 ret=0 errno=0 (-)
readv(file, iov, 0)                                  ret=0 errno=0 (-)
writev(file, NULL, 0)                                ret=0 errno=0 (-)
extpreadv(file, NULL, 0, 0, 0)                       ret=0 errno=0 (-)
extpwritev(file, NULL, 0, 0, 0)                      ret=0 errno=0 (-)
--- socket ---
readv(sock, NULL, 0)                                 ret=0 errno=0 (-)
writev(sock, NULL, 0)                                ret=0 errno=0 (-)
--- pipe ---
readv(pipe, NULL, 0)                                 ret=0 errno=0 (-)
writev(pipe, NULL, 0)                                ret=0 errno=0 (-)
--- /dev/zero ---
readv(/dev/zero, NULL, 0)                            ret=0 errno=0 (-)
--- negative control ---
readv(file, NULL, -1)                                ret=-1 errno=40 (Message too long)
readv(file, iov, 1) [sanity]                         ret=0 errno=0 (-)
DONE df2732