the result is shown below.

#
#	ls   (official ls in osx)
#
-bash$ ls /usr/bin|wc
    1108    1108    9719
-bash$ ls /dev|wc
     352     352    2428

#
#	david
#

-bash$ mk -f mkfile_david
9c -D__DARWIN_64_BIT_INO_T test_dirread.c
9c -D__DARWIN_64_BIT_INO_T dirread_david2.c
9l -o o.test_dirread test_dirread.o dirread_david2.o
-bash$ o.test_dirread .
.DS_Store root 501 416 0
_mp9dir.c root 501 200000320 0
_p9dir.c root 501 20000000106 0
a.out root 501 710 0
a1.c root 501 572 0
b1.c root 501 243 0
dirread.c.orig root 501 743 0
dirread1.c root 501 137 0
dirread_david.c root 501 473 0
...
-bash$ o.test_dirread /usr/bin |wc
     770    3850   20936
-bash$ o.test_dirread -a /usr/bin |wc
     770    3850   20936
-bash$ o.test_dirread /dev |wc
     320    1600    7739
-bash$ o.test_dirread -a /dev |wc
     320    1600    7739
-bash$

#
#	mine
#

-bash$ mk
9c -D__DARWIN_64_BIT_INO_T test_dirread.c
9c -D__DARWIN_64_BIT_INO_T mdirread2.c
9c -D__DARWIN_64_BIT_INO_T _mp9dir.c
9l -o o.test_dirread test_dirread.o mdirread2.o _mp9dir.o
-bash$ o.test_dirread .
.DS_Store arisawa staff 644 6148
_mp9dir.c arisawa staff 644 4948
_mp9dir.o arisawa staff 644 10284
_p9dir.c arisawa staff 444 4733
a.out arisawa staff 755 9552
a1.c arisawa staff 644 741
b1.c arisawa staff 644 2390
dirread.c.orig arisawa staff 444 3699
dirread1.c arisawa staff 644 3790
dirread_david.c arisawa staff 644 3768
...
-bash$ o.test_dirread /usr/bin |wc
    1108    5540   33034
-bash$ o.test_dirread -a /usr/bin |wc
    1108    5540   33034
-bash$ o.test_dirread /dev |wc
     352    1760   10308
-bash$ o.test_dirread -a /dev |wc
     352    1760   10308
-bash$

David idea is nice. I borrowed the idea:
	dir = fdopendir(dup(fd));
in mdirread2.c