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1 1 2I / O 12.1 I / O V I / O s e l e c tp o l l r e a d vw r i t e v I / Om m a p I / O F I F O F I F O i o c t l 14 I / O I / o p e n, r e a dw r i t e I / O (1) o p e n O _ N O N B L O C K 3. 3 (2) f c n t l O _ N O N B L O C K V O _ N D E L AY r e a d 0 U N I X r e a d 0 P O S I X. 1 O _ N D E L AY P O S I X. 1 r e a d1 e r r n o E A G A I NS V R 4 O _ N D E L AY P O S I X. 1O _ N O N B L O C K P O S I X. 1 O _ N D E L AY 4. 3 B S Df c n t l F N D E L AY 4. 3 B S D I / O

2 2 7 4 U N I X 4. 3 B S D E W O U L D B L O C K B S D P O S I X. 1O _ N O N B L O C K 4. 3 B S DF N D E L AY I / O B S D E W O U L D B L O C K P O S I X. 1E A G A I N B S D F I F O I / F I F O 12-1 I / O f o r c l r- f l 3-5 s e t _ f 1 s e t _ f w r i t e $ ls -l /etc/termcap -rw-rw-r-- 1 root Oct /etc/termcap $ a.out < /etc/termcap > temp.file read bytes nwrite = , errno = 0

3 1 2I/O $ ls -l temp.file -rw-rw-r-- 1 stevens Nov 21 16:27 temp.file w r i t e 12-1 $ a.out < /etc/termcap 2>stderr.out $ cat stderr.out read bytes nwrite = 8192, errno = 0 nwrite = 8192, errno = 0 nwrite = -1, errno = 11 nwrite = 4096,errno = 0 nwrite = -1, errno = 11 nwrite = 4096,errno = 0 nwrite = -1, errno = 11 nwrite = 4096,errno = 0 nwrite = -1, errno = 11 nwrite = -1, errno = 11 nwrite = 4096, errno = errno 11E A G A I N w r i t e w r i t e S V R 4 w r i t e w r i t e w r i t e E A G A I N S V R 4 I / O S V R 4 w r i t e 20 C P U I / O 1 7 I / O P o s t S c r i p t w r i t e 12.3 U N I X U N I X 16

4 2 7 6 U N I X record locking U N I X U N I U N I X 12-1 U N I X f c n t 1 l o c k f f l o c k P O S I X. 1 X P G 3 S V R 2 SVR3, SVR B S D 4.3BSD Reno P O S I X. 1 f c n t l V 4.3BSD Reno BSD flock P O S I X. 1f c n t l P O S I X. 1f c n t l Vl o c k f f c n t l 1980 John Bass V 7 l o c k i n g III Xenix SVR4Xenix S V R 2 V f c n t l fcntl f c n t l #include <sys/types.h> #include <unistd.h> #include <fcnt1.h> int fcnt1(int f i l e d e s,int c m d,.../* struct flock f l o * c k p t r */); c m d - 1 c m df _ G E T L KF _ S E T L KF _ S E T L K W f l o c k p t r f l o c k

5 1 2I/O f l o c k F _ R D L C K F _ W R L C K F _ U N L C l _ s t a r tl _ w h e n c e l _ s t a t l _ w h e n c e l s e e k 3. 6 l _ l e n l _ l e n0 l _ s t a r tl _ w h e n c e l _ s t a r t 0l _ w h e n c e S E E K _ S E Tl _ l e n 0 l _ t y p el _ R D L C K L _ W R L C f c n t l F_GETLK f l o c k p t r f l o c k p t r f l o c k p t l _ t y p e F _ U N L C K f l o c k p t r F_SETLK f l o c k p t r f c n t l e r r n o E A C C E SE A G A I N S V R 2S V R 4 E A C C E S E A G A I N B S D E A G A I NP O S I X. 1 f l o c k p t r l _ t y p ef _ U N L C K

6 2 7 8 U N I X F_SETLKW F _ S E T L K W w a i t f l o c k p t r F _ G E T L K F _ S E T L KF _ S E T L K W F _ S E T L K 0 ~ 99 0 ~ 49 0 ~ 4 50 ~ ~ ~ ~ 19 f l o c k 12-2 l o c k _ r e g 12-2 F _ G E T L K o u r h d r. h B #define read_lock(fd,offset,whence,len) \ l o c k _ r e g ( f d, F _ S E T L K, F _ R D L C K, o f f s e t, w h e n c e, l e n ) #define readw_lock(fd,offset,whence,len) \ l o c k _ r e g ( f d, F _ S E T L K W, F _ R D L C K, o f f s e t, w h e n c e, l e n ) #define write_lock(fd,offset,whence,len) \ l o c k _ r e g ( f d, F _ S E T L K, F _ W R L C K, o f f s e t, w h e n c e, l e n ) #define writew_lock(fd,offset,whence,len) \ l o c k _ r e g ( f d, F _ S E T L K W, F _ W R L C K, o f f s e t, w h e n c e, l e n ) #define un_lock(fd,offset,whence,len) \ l o c k _ r e g ( f d, F _ S E T L K, F _ U N L C K, o f f s e t, w h e n c e, l e n ) l s e e k 12-3 l o c k _ t e s t

7 1 2I/O I D 0 o u r h d r. h #define is_readlock(fd,offset,whence,len) \ l o c k _ t e s t ( f d, F _ R D L C K, o f f s e t, w h e n c e, l e n ) #define is_writelock(fd,offset,whence,len) \ l o c k _ t e s t ( f d, F _ W R L C K, o f f s e t, w h e n c e, l e n ) T E L L _ x x xwa I T _ x x x,

8 2 8 0 U N I X $ a. o u t child:got the lock,byte 0 parent:got the lock,byte 1 child:writew_lock error:deadlock situation detected/avoided parent:got the lock,byte (1) fd1=open(pathname,...); read_lock(fd1,...); f d 2 = d u p ( f d 1 ); c l o s e ( f d 2 ); c l o s ef d 2 f d 1 d u p o p e n fd1=open(pathname,...); read_lock(fd1,...); fd2=open(pathname,...);

9 1 2I/O c l o s e ( f d 2 ) ; (2) f o r k f o r k f c n t l (3) e x e c P O S I X. 1 S V R B S D BSD B S D pause( ) f d v v v v i f d I D B S D I D

10 2 8 2 U N I X o p e nf o r k d u p f l o c k i f l o c k f l o c k w r i t e _ l o c r e a d _ l o c k I D f d 1f d 2f d 3 i f l o c k I D P I D I D I D 12-5 I D I D I \ n I D \ n 654 \ n 5 \ n 0 f t r u n c a t e o p e n O _ T R U N C 0 O _ T R U N C f o r ke x e c 12-5

11 1 2I/O l _ w h e n c es E E K _ C U R S E E K _ E N D l _ s t a r t 12-6, 0 1 S V R

12 2 8 4 U N I X $ a. o u t writew_lock error: No record locks available $ ls-l temp.lock -rw-r--r-- 1 stevens other 592 Nov 1 04:41 temp.lock E N O L C K w r i t e w _ l o c kw r i t e w r i t e w _ l o c k u n _ l o c k u n _ l o c k f o r w r i t e w _ l o c k 12-3 u n _ l o c k 12-4 f o r w r i t e f c n t l e r n o E N O L C K un_lock l_start 1 un_lock _ d b _ w r i t e d a t_ d b _ w r i t e i d x cooperating pro c e s s o p e nr e a dw r i t e S V R 4 P O S I X I D -

13 1 2I/O I D S V R 3 r e a d w r i t e E A G A I N EAGAIN EAGAIN 12-3 r e a d, w r i t e o p e n r e a dw r i t e 12-3 o p e n f l a g O _ T R U N CO _ C R E AT O _ N O N B L O C K, o p e n e r r n o E A G A I N O _ T R U N C 0 O _ C R E AT e r r n o U N I X e d e d e d u n l i n k S V R 4 t r u s s ( 1 ) B S D k t r a c e ( 1 )k d u m p ( 1 ) v i v i E A G A I N w r i t e v i K o r n S h e l l>> > cannot creat Bourne shell > > > Korn ShellO _ C R E ATO _ A P P E N D O _ C R E AT Bourne shell O _ C R E AT o p e n w r i t e

14 2 8 6 U N I X

15 1 2I/O f o r k E A C C E SE A G A I N r e a d E A C C E SE A G A I N r e a d S V R 4 $ a. o u t read_lock of already-locked region returns 13 read failed (mandatory locking works):no more processes i n t r o ( 2 ) 13 E A C C E S r e a d No more processes f o r k B S D $ a. o u t read_lock of already_locked region returns 35 read OK (no mandatory locking),buff=ab e r r n o 35 E A G A I N U N I X B S Dv i v i v i f o r k v i v i v i w a i t e x e c S V R 4 S V R 4 v ie d 1 6

16 2 8 8 U N I X 12.4 V (1) V (2) I/O (3) Dennis Ritchie Ritchie 1984, I / O S V R 3S V R 4 I / O AT&T 1990d S V R 4 I / O i o c t l d o w n s t r e a m u p s t r e a m l d t e r m AT&T 1990d 7 AT&T ) 3 o p e nc l o s er e a dw r i t ei o c t l S V R 3

17 1 2I/O g e t m s gp u t m s gp o l l S V R 4 g e t p m s gp u t p m s g / d e v l s - l, c l i s t ( B a c h L e ff l e r ) S V R B S D clist r e a d, w r i t e r e a dw r i t eg e t m s gg e t p m s g p u t m s gp u t p m s g 12-4 w r i t ep u t m s gp u t p m s g s t r b u f 12-4 w r i t ep u t m s gp u t p m s g?? E I N VA L E I N VA L 0 E I N VA L E I N VA L

18 2 9 0 U N I X p u t m s gp u t p m s g l e n g e t m s gg e t p m s g maxlen l e n 0 l e n 1 O l a n d e r, McGrathI s r a e l1 986 V AT & T [ 1990 d ] 5 V ( T L I ) S t e v e n s i o c t l w r i t e N w r i t e p u t m s gg e t m s g 25 r e a dw r i t eg e t m s g g e t p m s gp u t m s gp u t p m s g M_DATAI / O M_PROTO M_PCPROTO 0 1 ~ w r i t ep u t m s gp u t p m s g M _ S I G putmsgp u t p m s g p u t m s gp u t p m s g #include <stropts.h> int putmsg(int f i l e d e s,const struct strbuf c t l p * t r, const struct strbuf d a t * a p t r,int f l a g) ; int putpmsg(int f i l e d e s,const struct strbuf c t l p * t r, const struct strbuf d a t * a p t r,int b a n d,int f l a g) ; 0-1

19 1 2I/O w r i t e f l a g0p u t m s g c t l p t r c t l p t r- > l e n 1 c t l p t r c t l p t r- > l e n 0 d a t a p t r c t l p t r ioctl i o c t l I / O S V R 4 i o c t l 29 s t r e a m i o ( 7 ) AT & T 1990 d < s t r o p t s. h > C i o c t l re q u e s t 29 re q u e s t I _ re q u e s t i s a s t r e a m i s a t t y S V R 4 i s a s t r e a m int isastream(int f i l e d e s) ; 1 0 S V R 4 # i n c l u d e i s a t t y i o c t l 12-8 I_CANPUT ioctl i o c t l i s a s t r e a m

20 2 9 2 U N I X i o c t l $ a.out /dev/tty /dev/vidadm /dev/null /etc/motd /dev/tty:/dev/tty:streams device /dev/vidadm:/dev/vidadm:not a stream:invalid argument /dev/null:/dev/null:not a stream:no suck device /etc/motd: /etc/motd:not a stream:not a typewriter / d e v / t t ys V R / d e v / v i d a d m i o c t l i o c t E I N VA L / d e v / n u l l i o c t l i o c t E N O D E V / e t c / m o t d E N O T T Y E N O T T YNot a typewriter i o c t l U N I X E N O T T Y i o c t l re q u e s ti _ L I S T AT & T d 10 s t r _ l i s t struct str_list { i n t sl_nmods; /* number of entries in array */ struct str_mlist *sl_modlist; /* ptr to first element of array */ }; s l _ m o d l i s t s t r _ m l i s t s l _ n m o d s struct str_mlist { char 1_name[FMNAMESZ+1]; /* null terminated module name */ }; F M N A M E S Z < s y s / c o n f. h > 8l _ n a m e

21 1 2I/O F M N A M E S Z n u l l i o c t l 0 i o c t l s t r _ m l i s t I _ L I S T i o c t l $ w h o s t e v e n s c o n s o l e Sep 25 06:12 s t e v e n s p t s 001 Oct 12 07:12 $ a.out /dev/pts001 #modules= 4 module: ttcompat module: ldterm module: ptem driver: pts $ a.out /dev/console

22 2 9 4 U N I X #modules= 5 module: ttcompat module: ldterm module: ansi module: char driver: cmux t t c o m p a tl d t e r m write 12-4 w r i t e M _ D ATA w r i t e write 0 F I F O 0 F I F O 0w r i t e i o c t l F I F O i o c t l re q u e s t I _ G W R O P T re q u e s t I _ S W R O P T 3. 13,, ( ) SNDZERO F I F O0 0 SNDPIPE w r i t ep u t m s g S I G P I P E g e t m s gg e t p m s g getmsgg e t p m s g #include <stropts.h> int getmsg(int f i l e d e s,struct strbuf c t * l p t r, struct strbuf d a * t a p t r,int * f l a g p t r) ; int getpmsg(int f i l e d e s,struct strbuf c t * l p t r, struct strbuf d a * t a p t r, int *b a n d p t r, int *f l a g p t r) ; - 1 f l a g p t rb a n d p t r

23 1 2I/O f l a g p t r 0 g e t m s g f l a g p t r R S _ H I P R I g e t m s g f l a g p t r R S _ H I P R I g e t p m s g b a n d p t r ( a )f l a g p t rb a n d p t r (b) (c) d a t a p t rc t l p t r, (d) c t l p t r- >m a x l e nd a t a p t r- >m a x l e n g e t m s g g e t m s g r e a d ( 1 ) ( 2 ) r e a d r e a d r e a d i o c t l re q u e s t I _ G R D O P T re q u e s t I _ S R D O P T RNORM RMSGN RMSGD r e a d RPROTNORM - r e a d e r r n o E B A D M S G RPROTDAT RPROTDIS - r e a d - r e a d g e t m s g r e a d S V R 4 $ echo hello,world a.out f l a g = 0, c t l. l e n = - 1, d a t. l e n = 13 h e l l o, w o r l d f l a g = 0, c t l. l e n = 0, d a t. l e n = 0 $ a. o u t this is line 1 f l a g = 0, c t l. l e n = - 1, d a t. l e n = 15 this is line 1 and line 2 f l a g = 0, c t l. l e n = - 1, d a t. l e n = 11

24 2 9 6 U N I X and line 2 ˆ D f l a g = 0, c t l. l e n = - 1, d a t. l e n = 0 $ a.out < /etc/motd getmsg error:not a stream device E O F e c h o g e t m s g g e t m s g 12.5 I/O I / O while ( (n=read(stdin_fileno, buf, BUFSIZ) ) > 0) if (write (STDOUT_FILENO, buf, n)!= n) err_sys (write error ) ; I / O I /

25 1 2I/O r e a d r e a d S I G C H L D S I G U S R 1 I / O r e a d r e a d C P U r e a d C P I / O I / Oasynchronous I/O I / O P O S I X S V R 4 S I G P O L L B S D S I G I O 1 I / O I / O I / O I / O I/O multiplexing I / O I / O

26 2 9 8 U N I X I / O P O S I X S V R B S D s e l e c t I / O p o l l S V R 4 S V R 4 p o l l s e l e c t I / O B S D s e l e c t I / O I / O S V R 3 p o l l S V R 4 p o l l S V R 4 p o l l s e l e c tp o l l B S D s e l e c t B S D S A _ R E S TA RT S V R 4 S A _ R E S TA RT s e l e c tp o l l S V R 4 s e l e c tp o l l s i g n a l _ i n t r select select SVR44.3+BSD I/O select (1) (2) (3) s e l e c t (1) (2) I / O r e a dw r i t e #include <sys/types.h>/* fd_set data type */ #include <sys/time.h> /* struct timeval */ #include <unistd.h> /* function prototype might be here */ int select (int m a x f d p 1, fd_set *re a d f d s, fd_set *w r i t e f d s, fd_set *e x c e p t f d s, struct timeval * t v p t r) ; 0-1 struct timeval{ long tv_sec; /* seconds */ long tv_usec; /* and microseconds */ } t v p t r= =NULL s e l e c t 1e r r n o E I N T R t v p t r- >t v _ s e c= =0 && t v p t r- >t v _ u s e c= =0

27 1 2I/O s e l e c t t v p t r- >t v _ s e c! =0 t v p t r- >t v _ u s e c! =0 0 t v p t r- >t v _ u s e c re a d f d sw r i t e f d se x c e p t f d s f d _ s e t s e l e c t f g _ s e t ( a ) ( b ( c ) fd_set int rset; fd; F D _ Z E R O FD_ZERO (&rset); FD_SET (fd,&rset); FD_SET (STDIN_FILENO,&rset); s e l e c t F D _ I S S E T if (FD_ISSET(fd, &rset)){... }

3 0 0 U N I X s e l e c t s e l e c t s l e e p 10. 19 s l e e s e l e c t 1 12. 6 s e l e c t m a x f d p1 f d1max fd plus 1 1 F D _ S E T S I Z E < s y s / t y p e s.

28 3 0 0 U N I X s e l e c t s e l e c t s l e e p s l e e s e l e c t s e l e c t m a x f d p1 f d1max fd plus 1 1 F D _ S E T S I Z E < s y s / t y p e s. h > ~ 10 1 fd_set readset, writeset; F D _ Z E R O (& r e a d s e t ); F D _ Z E R O (& w r i t e s e t ); FD_SET(0, &readset); FD_SET(3, &readset); FD_SET(1, &writeset); FD_SET(2, &writeset); select (4, &readset, &writeset, NULL, NULL); select s e l e c t (1) 1 (2) 0 (3)

29 1 2I/O B S D S V R 4 S V R 4B S Ds e l e c t B S D S V R 4 P O S I X s e l e c t (1) re a d f d s r e a d (2) w r i t e f d s w r i t e (3) e x c e p t f d s ( a ) ( b S t e v e n s s e l e c t 5 s e l e c t s e l e c t 5 s e l e c t s e l e c t r e a d 0 U N I X s e l e c t poll S V R 4p o l l s e l e c t p o l l S V R 4 #include <stropts.h> #include <poll.h> int poll(struct pollfd f d a rr a y[],unsigned long n f d s,int t i m e o u t) ; 0-1 s e l e c t p o l l p o l l f d struct pollfd { i n t f d ; /* file descriptor to check, or < 0 to ignore */ s h o r t e v e n t s ; /* events of interest on fd */ s h o r t r e v e n t s ; /* events that occurred on fd */ } ; f d a rr a y n f d s S V R 3 n f d s unsigned long S V R 4 p o l l s i z e _ t < p o l l. h > unsigned long

30 3 0 2 U N I X S V R 4S V I DAT & T 1989 p o l l struct pollfd f d a rr a y[ ], S V R 4 AT&T 1990 d struct pollfd *f d a rr a y C f d a rr a y e v e n t s 12-5 r e v e n t s p o l l e v e n t s s e l e c t s e l e c t 12-5 polle v e n t sr e v e n t s e v e n t s r e v e n t s ( 0 ) 0 P O L L O U T e v e n t s r e v e n t s P O L L H U P p o l l s e l e c t timeout == INFTIM INFTIM <stropts.h>, 1 p o l l 1 errno EINTR t i m e o u t == 0 p o l l timeout > 0 t i m e o u t 0 t i m e o u t P O L L I N r e a d 0P O L L H U Pr e v e n t s r e v e n t s P O L L H U P s e l e c t p o l l

31 1 2I/O I / O s e l e c tp o l l I / O, s e l e c tp o l l 10 S V R B S D S V R 4 S I G P O L L B S D S I G I O I / O S V R 4s e l e c tp o l l 4 B S D s e l e c t I / O S V R 4 I / O B S D I / O S V R B S D I / O I / O SVR4 V I / O S V R 4 I / S I G P O L L I / O i o c t l re q u e s t I _ S E T S I G 12-6 < s t r o p t s. h > 12-6 S I G P O L L 0 S _ R D B A N D 0 S I G U R G S I G P O L L S _ O U T P U T 0 S I G P O L L M _ E R R O R M _ H A N G U P i o c t l S I G P O L L 10-1 S I G P O L L i o c t l BSD B S D I / O S I G I OS I G U R G I / O

32 3 0 4 U N I X S I G I O (1) s i g n a ls i g a c t i o n (2) F _ S E TO W N f c n t l I D I D (3) F _ S E T F L f c n t l O _ A S Y N C I / O 3-2 ( 3 ) B S D S I G U R G ( 1 ) ( 2 ) 12.7 readvw r i t e v r e a d vw r i t e v scatter re a d gather write #include <sys/types.h> #include <sys/uio.h> ssize_t readv(int f i l e d e s,const struct iovec i o v[ ],int i o v c n t) ; ssize_t writev(int f i l e d e s,const struct iovec i o v[ ],int i o v c n t) ; - 1 i o v e c struct iovec { void *iov_base; /* starting address of buffer */ size_t iov_len; /* size of buffer */ }; i o v i o v c n t 4. 2 B S D S V R 4 i o v e c S V R 4 AT&T 1990eS V R 4S V I DAT & T 1989 S V R B S D < s y s / u i o. h > S V I DS V R POSIX r e a dw r i t ep O S I X. 1 void * s i z e _ t, s s i z e _ t r e a d v c o n s t B S D S V R 4 r e a d v i o v e c i o v _ b a s e 4. 3 B S DS V R 4i o v c n t B S D U I O _ M A X I O V 1024S V I D I O V _ M A X V S V R r e a d vw r i t e v i o v e c w r i t e v i o v[0], i o v[ 1 ]

33 1 2I/O iov[iovcnt-1] writev r e a d v r e a d r e a d v I readvw r i t e vi o v e c _ d b _ w r i t e i d x (1) w r t r e, (2) w r t r e (3) w r i t e v w r i t e v w r i t e v w r i t e w r i t e w r i t e C P U C P U w r i t e w r i t w r i t e v 3-1 C P U w r i t e w r i t e v w r i t e S PA R C S PA R C

34 3 0 6 U N I X 386 C P U r e a d vw r i t e v r e a dw r i t e w r i t e w r i t e v C P U 12.8 readnw r i t e n, S V R 4 (1) r e a d (2) w r i t e w r i t e 18 S V R 4 BSD UNIX r e a d nw r i t e n N r e a dw r i t e N #include "o u r h d r. h" ssize_t readn(int f i l e d e s,void *b u f f,size_t n b y t e s) ; ssize_t writen(int f i l e d e s,void *b u f f,size_t n b y t e s) ; - 1 w r i t e n r e a d n r e a d w r i t e nr e a d n writen

35 1 2I/O readn 12.9 I / O I / O r e a dw r i t e I / O m m a p #include <sys/types.h> #include <sys/mman.h> caddr_t mmap(caddr_t a d d r, size_t l e n,int p ro t,int f l a g, int f i l e d e s,off_t o f f) ; - 1 I / O 4. 1 B S D1 981 v r e a dv w r i t e I / O4. 2 B S D m m a p L e ff l e r[ 1989 ] B S D m m a p G i n g e l l, M o r a ns h a n n o n1 987 m m a p S V R B S D m m a p c a d d r _ t char *a d d r 0 f i l e d e s l e n o f f o f

36 3 0 8 U N I X ( b s s ) m m a p 12-8 p ro c 12-8 o p e n P R O T _ W R I T E f l a g MAP_FIXED a d d r a d d r0 a d d r a d d r 0 MAP_SHARED w r i t e M A P _ P R I VAT E MAP_PRIVATE B S D M A P _ x x x 4.3+BSD mmap2 ( B S D) o f fa d d r M A P _ F I X E D S V R

37 1 2I/O S C _ PA G E S I Z Es y s c o n f B S D < s y s / p a r a m. h > N B P G o f fa d d r S I G S E G VS I G B U S S I G S E G V m m a p S I G B U S S I G B U S f o r k e x e c m u n m a p f i l e d e s #include <sys/types.h> #include <sys/mman.h> int munmap(caddr_t a d d r,size_t l e n) ; 0-1 munmap m u n m a p M A P _ S H A R E D m s y n c f s y n I / O c p ( 1 ) f s t a t m m a p l s e e k m m a p S I G B U S f t r u n c a t e m m a p m e m c p y s r c d s t I / O

38 3 1 0 U N I X r e a dw r i t e read/writem m a p / m e m c p y S PA R C r e a d / w r i t e m m a p / m e m c p y S PA R C C P U w r i t e v 386m m a p / m e m c p y r e a d / w r i t e mmap SPARC386 I/O read/write I/O m m a p / m e m c p y I / O

39 1 2I/O I / O I / O - K r i e g e r, S t u m mu n r a u I / O I / O I / O S V R B S D I / O I / O I / O I / O V I/O s e l e c tp o l l readvw r i t e v I / Om m a p f o r w r i t e < s y s / t y p e s. h > s e l e c t F D _ 12. 3< s y s / t y p e s. h > f d _ s e t f d _ s e t g e t m s g s e l e c tp o l l s l e e p s l e e p _ u s B S D u s l e e p T E L L _ WA I TT E L L _ PA R E N T T E L L _ C H I L DWA I T _ PA R E N T WA I T _ C H I L D s e l e c tp o l l 2 P I P E _ B U F m m a p c l o s e I / O

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