IPC

1
????????? ??????

• ??. ??. ?????? ???????????, ??????? ????????????
  ???????

2
??????????

• ?????? ????????? ??????
• ????????? ?? ????????? ?????
• ?????? ? ????????? ?????
• ?????? ?? ????????? ?????
• ????????? ?? ????????? ?????
• ????????? ?? FIFO ????

3
?????? ????????? ??????

• ??????????? ????????? ?????? (unnamed pipe)
• ????????? ????????? ?????? (named pipe, FIFO
  file)

4
????????? ?? ????????? ?????

• int pipe(int fd2)
• ????? 0 ??? ?????, -1 ??? ??????.
• fd0 - ?????? ?????????? ?? ?????? ?? ??????
• fd1 - ?????? ?????????? ?? ?????? ? ??????

5
?????? ? ????????? ?????

• ssize_t write(int fd, char buf, size_t nbytes)
• fd ? ?????? ?????????? ?? ?????? ? ?????????
  ?????.
• ??? ? ?????? ??? ?????????? ?????, ?? ??????? ??
  ???????? ? ???? ?? ?????, ????????? ?? ??????? ??
  ????? ? ?? ???????? ?????? ???????, ?????? ??
  ????? ?? ??????.
• ??? ? ?????? ???? ?????????? ????? ?? ????????
  ????? ? nbytes ? ??-????? ??? ????? ?? PIPE_BUFF
  (??? ?????????? ?? ??????), ?? ?????? ???????
  ???????. ?????? ???? ??????? ?? ???? ??????,
  ?????????? read, ??? ?????????? ????? ? ?????? 1.
• ??? ? ?????? ???? ?????????? ????? ?? ????????
  ?????, ?? nbytes ? ??-????? ?? PIPE_BUFF (???
  ?????????? ?? ??????), ?? ? ?????? ?? ????????
  ??????? ?????, ??????? ? ???????? ? ??????
  ??????? ???????. ?????? ???? ???????, ???
  ?????????? ?? ????.

6
?????? ?? ????????? ?????

• ssize_t read(int fd, char buf, size_t nbytes)
• fd ? ?????? ?????????? ?? ?????? ?? ?????????
  ?????.
• ??? ? ?????? ??? ??????? ?????, ?? ??????? ??????
  ?? ???????? ?? ????? ?????? ?? ???????????
  ???????? ?? ??????? ??? ?????? ??? ????? ?
  ??????. ???????? ??????? ?? ????? ? ??????????
  ???? ????? ? ??????? ?????? ???????, ?????? ??
  ????? ? ??????.
• ??? ??????? ? ??????, ?????? ??????? ???????.
  ?????? ???? ??????? ?? ???? ??????, ??????????
  write, ??? ?????????? ????? ? ?????? 1.

7
????????? ?? ????????? ?????

• int close(int fd)
• fd ? ?????? ?????????? ?? ??????/?????? ?
  ????????? ?????.
• ??? ??? close ?? ???????? ?????????? ??????
  ?????????? ?? ?????? ? ??????, ?? ?? ????????
  ?????? ???????, ?????? ?? ????? ?? ??????, ????
  read ????? 0.
• ??? ??? close ?? ???????? ?????????? ??????
  ?????????? ?? ?????? ?? ??????, ?? ?? ????????
  ?????? ???????, ?????? ?? ????? ? ?????? ???? ??
  ?? ??????? ?????? SIGPIPE.
• ??? ??? close ?? ???????? ?????????? ??????
  ?????????? ?? ??????? ? ?? ? ?????? ? ??????, ??
  ??????????? ????? ?? ?????????.

8
??????????? ????? ??? ??????? ? pipe

• - ???????? ??????? ????????? ????? ? pipe
• - ???????? ??????? ??? ?????? ? fork
• - ?????? ??????? ???????? ?????????? ?? ??????, ?
  ???? ?? ?????? ? ?????????? ?????.

9
??????. ??????????? ?? ???? ??? ??? ? pipe

• include "ourhdr.h"
• main(void)
• int pd2, n
• pid_t pid
• char buff1024
• if (pipe(pd) lt 0) / parent creates a pipe
  /
• perror("pipe error") exit(1)
• if ((pid fork()) lt 0)
• perror("fork error") exit(1)
• else if ( pid gt 0) / in parent process /
• close(pd0)
• write(pd1, "Hello World\n", 12)
• else / in child process /
• close(pd1)
• n read(pd0, buff, 1024)
• write(1, buff, n)
• exit(0)

10
??????. ???????????? ?? ???????? "ls wc -l"

• ????? ???????
• ????????, ? ????? ?????? ??????????, ??????? ???
  ???? ????? ???? ???????????? ??.
• ????? ??????? ????????? ????? ? ???? ??????? ???
  (???? ?? ???????, ? ????? ?????? ??????????).
• ????????-??? ??????? ?????????? wc.
• ????????-???? ??????? ?????????? ls.
• ????????-?????? ???? ???????????? ?? ???????-???.
• ????? ???????
• ????? ??????? ?? ????????? ls ? wc ?? ?????? ??
  ???????, ? ????? ?????? ??????????.
• ????????? ?? ls ? wc ?? ? ???? ????? ? ????? ls.
• ????????-???? ???? ???????????? ?? ?????? ???
  (wc).

11
????? ??????? (1)

• include "ourhdr.h"
• main (void)
• int pd2, status
• pid_t pid
• if ( (pid fork() ) lt 0 )
• err_sys_exit("fork error")
• if ( pid 0 ) / in child /
• if (pipe(pd) lt 0)
• err_sys_exit("pipe error")
• if ( (pid fork() ) lt 0)
• err_sys_exit("fork error")
• else if ( pid 0 ) / in grandchild /
• close(1)
• dup(pd1)
• close(pd0)
• close(pd1)
• execlp("ls", "ls", 0)
• err_sys_exit("exec ls error")

12
????? ??????? (2)

• else / in child /
• close(0)
• dup(pd0)
• close(pd0)
• close(pd1)
• execlp("wc", "wc", "-l", 0)
• err_sys_exit("exec wc error")
• wait(status) / in parent /
• printf("Parent after end of pipe statusd\n",
  status)
• exit(0)

13
????? ??????? (?????? ???????)

• main (void)
• int pd2, status
• if ( fork() 0 ) / in child /
• pipe(pd)
• if ( fork() 0) / in grandchild /
• close(1)
• dup(pd1)
• close(pd0)
• close(pd1)
• execlp("ls", "ls", 0)
• perror("exec ls error") exit(1)
• else / in child /
• close(0)
• dup(pd0)
• close(pd0)
• close(pd1)
• execlp("wc", "wc", "-l", 0)
• perror("exec wc error") exit(1)

14
????? ??????? (1)

• include "ourhdr.h"
• main (void)
• int pd2, status
• pid_t pid, pid2
• if ( pipe(pd) lt 0 )
• err_sys_exit("pipe error")
• if ( (pid fork() ) lt 0 )
• err_sys_exit("fork error for first child")
• if ( pid 0 ) / in first child /
• setpgrp()
• printf("First pidd, grpd, ppidd\n",
  getpid(), getpgrp(), getppid())
• close(1)
• dup(pd1)
• close(pd0)
• close(pd1)
• execlp("ls", "ls", "-l", 0)
• err_sys_exit("exec ls error")

15
????? ??????? (2)

• if ( (pid2 fork() ) lt 0 ) / in parent /
• err_sys_exit("fork error for second child")
• if ( pid2 0 ) / in second child /
• setpgid(0, pid)
• printf("Second pidd, grpd,
  ppidd\n",getpid(),getpgrp(),getppid())
• close(0)
• dup(pd0)
• close(pd0)
• close(pd1)
• execlp("wc", "wc", "-l", 0)
• err_sys_exit("exec wc error")
• close(pd0) / in parent /
• close(pd1)
• waitpid(pid2, status, 0)
• printf("Parent after end of pipe statusd\n",
  status)
• exit(0)

16
????????? ?? FIFO ????

• int mknod(const char filename, mode_t mode,
• dev_t dev)
• ????? 0 ??? ?????, -1 ??? ??????.
• int mkfifo(const char filename,
• mode_t mode)
• ????? 0 ??? ?????, -1 ??? ??????.
• ??????
• int mknod("fifoname", S_IFIFO0600, 0)
• int mkfifo("fifoname", 0600)

17
??????. ??????????? ?? ???? ??? ??? ? FIFO ????

• include "ourhdr.h"
• include ltfcntl.hgt
• main(int argc, char argv)
• int fdr, fdw, n
• pid_t pid
• char buffMAXLINE
• if (argc lt 2)
• err_exit("usage a.out fifo_name")
• if (mknod(argv1, S_IFIFO0600, 0) lt 0)
  / or mkfifo(argv1, 0600) /
• err_sys_exit("make fifo error")
• if ((pid fork()) lt 0)
• err_sys_exit("fork error")
• else if (pid gt 0) / in parent /
• if ((fdw open(argv1, O_WRONLY)) -1)
• err_sys_exit("open for write error")
• write(fdw, "Hello World\nHello World\n",
  24)
• else / in child /
• if ((fdr open(argv1, O_RDONLY)) -1)

18
???????? ?? ??????????

• a.out myfifo
• Hello World
• ls -l myfifo
• prw------- 1 moni staff 0 Jul 21 1022 myfifo
• rm myfifo

19
??????. ????????????-?????????? ? FIFO ????

• / Producer with fifo file /
• include "ourhdr.h"
• include ltfcntl.hgt
• main(int argc, char argv)
• int fd, n
• if (argc lt 2)
• err_exit("usage prod fifo_name")
• if (mkfifo(argv1, 0600) lt 0)
• err_sys_exit("prod make fifo error")
• if ((fd open(argv1, O_WRONLY)) lt 0)
• err_sys_exit("prod open fifo error")
• for (n1 nlt100 n)
• if ( write(fd, n, sizeof(int)) lt 0 )
• err_sys_exit("write error")

20

• / Consumer with fifo file /
• include "ourhdr.h"
• include ltfcntl.hgt
• main(int argc, char argv)
• int fd, n
• int buff
• if (argc lt 2)
• err_exit("usage cons fifo_name")
• if ( (fd open(argv1, O_RDONLY) ) lt 0)
• err_sys_exit("cons open fifo error")
• while ( ( n read(fd, buff, sizeof(int)) ) gt
  0 )
• buff 2
• printf("Consumer d \n", buff)
• if (unlink(argv1) -1)

21
???????? ?? ??????????

• prod myfifo
• 1 5808
• cons myfifo
• Consumer 2
• Consumer 4
• Consumer 6
• Consumer 8
• Consumer 10
• Consumer 12
• . . .
• Consumer 200
• 1 Done prod myfifo
• ls -l myfifo
• ls myfifo No such file or directory