Тексты программ
Текст программы - semdemo.c
 1       #include <unistd.h>
 2       #include <stdlib.h>
 3       #include <sys/types.h>
 4       #include <sys/ipc.h>
 5       #include <sys/sem.h>
 6       #include <stdio.h>
 7       #define  DUMMY  0
 8       #define  COUNT  4
 9
10       main(int argc, char *argv[])
11       {
12       key_t ipckey;
13       int semid, pid, creator, i;
14       static struct sembuf lock =
15       { 0, -1, SEM_UNDO };
16       static struct sembuf unlock =
17       { 0, 1, SEM_UNDO };
18
19       setbuf(stdout, (char *) NULL);
20       ipckey = ftok(argv[0], 's');
21       if ((semid = semget(ipckey, 1,
22       IPC_CREAT | IPC_EXCL | 0666)) != -1) {
23       creator = 1;
24       }
25       else {
26       if ((semid = semget(ipckey, 1, 0)) == -1) {
27       perror(argv[0]);
28       exit(1);
29       }
30       creator = 0;
31       }
32       if (creator) {/* initialize semaphore */
33       if (semctl(semid, 0, SETVAL, 1) == -1) {
34       perror(argv[0]);
35       exit(2);
36       }
37       }
38
39       pid = getpid();
40       for (i = 0; i < COUNT; i++ ) {
41       if (semop(semid, &lock, 1) == -1) {
42       perror(argv[0]);
43       exit(3);
44       }
45       printf("[%d] locking\t", pid);
46       sleep(1);/* terminal output being used */
47       printf("[%d] unlocking\n", pid);
48       if (semop(semid, &unlock, 1) == -1) {
49       perror(argv[0]);
50       exit(4);
51       }
52       }
53
54       if (creator) {
55       sleep(5);
56       if(semctl(semid, DUMMY, IPC_RMID, DUMMY) == -1) {
57       perror(argv[0]);
58       exit(5);
59       }
60       }
61       return(0);
62       }
Текст программы - printer.c
 1 #include <stdlib.h>
 2 #include <string.h>
 3 #include <unistd.h>
 4 #include <fcntl.h>
 5 #include <sys/types.h>
 6 #include <sys/ipc.h>
 7 #include <sys/sem.h>
 8 #include <stdio.h>
 9 #include "printer.h"
10
11 main(int argc, char *argv[])
12 {
13      char *printer[NUMPR + 1],buf[BUFSIZ],errmsg[30];
14      key_t ipckey;
15      ushort initial[NUMPR + 1], prntnum;
16      int n, creator, fdin, fdout, semid;
17      struct sembuf operation[2];
18
19      if ((printer[1] = getenv("PRINTER1")) == NULL ||
20          (printer[2] = getenv("PRINTER2")) == NULL) {
21          printf("missing printer assignment\n");
22          exit(1);
23      }
24      if (strncmp(argv[0], "line", 4) == 0)
25          prntnum = 1;
26      else if (strncmp(argv[0], "lase", 4) == 0)
27          prntnum = 2;
28      else            /* random choice */
29          prntnum = getpid() % NUMPR + 1;
30
31      ipckey = ftok(argv[0], 's');
32      if ((semid = semget(ipckey, NUMPR + 1,
33          IPC_CREAT | IPC_EXCL | 0666)) != -1) {
34          creator = 1;
35      }
36      else {
37          if ((semid = semget(ipckey, NUMPR + 1,
38                0666)) == -1) {
39                sprintf(errmsg,"%s - semget", argv[0]);
40                perror(errmsg);
41                exit(2);
42          }
43          creator = 0;
44      }
45      if (creator) { /* initialize semaphore set */
46          initial[0] = NUMPR;
47          for (n = 1; n <= NUMPR; n++)
48                initial[n] = 1;
49          if(semctl(semid,DUMMY,SETALL,initial) == -1) {
50             sprintf(errmsg,"%s - SETALL", argv[0]);
51             perror(errmsg);
52             exit(3);
53       }
54  }
55


56  operation[1].sem_num = prntnum;
57  operation[1].sem_op = ACQUIRE;
58  operation[1].sem_flg = SEM_UNDO;
59  operation[0].sem_num = 0;
60  operation[0].sem_op = ACQUIRE;
61  operation[0].sem_flg = SEM_UNDO;
62  if (semop(semid, operation, 2) == -1) {
63       sprintf(errmsg,"%s - ACQUIRE", argv[0]);
64       perror(errmsg);
65       exit(4);
66  }
67  if ((fdin = open(argv[1], O_RDONLY)) == -1) {
68       sprintf(errmsg,"%s - %s", argv[0], argv[1]);
69       perror(errmsg);
70       exit(5);
71  }
72  if((fdout=open(printer[prntnum],O_CREAT | O_WRONLY,0644)) == -
1) {
73          sprintf(errmsg,"%s - %s",argv[0],printer[prntnum]);
74          perror(errmsg);
75          exit(6);
76      }
77      while ((n = read(fdin, buf, BUFSIZ)) > 0)
78          write(fdout, buf, n);
79      operation[1].sem_op = RELEASE;
80      operation[0].sem_op = RELEASE;
81      if (semop(semid, operation, 2) == -1) {
82          sprintf(errmsg,"%s - RELEASE", argv[0]);
83          perror(errmsg);
84          exit(7);
85      }
86
87       }