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Subject: NETWORK PROGRAMMING LAB Year : 2010 Class : IV B-Tech C.S.E Semester: First WEEK 4: Aim: Write a program to create an integer variable using shared memory concept and increment the variable simultaniously two processes. Use semaphores to avoid race conditions. /*file name sem.c */ #include #include #include #include #include #include #include #include #include #include #include # include #define SHMSZ 4 /* Good for integer */ #define BUF_SZ 16 #define SHM_KEY 1234 #define SEM_KEY 1235 #define CHILD_INCREMENT_COUNT 67787 #define PARENT_INCREMENT_COUNT 84823 union semun { int val; /* value for SETVAL */ struct semid_ds *buf; /* buffer for IPC_STAT, IPC_SET */ unsigned short *array; /* array for GETALL, SETALL */ /* Linux specific part: */ struct seminfo *__buf; /* buffer for IPC_INFO */ }; NP Lab Manual , RNEC page: 18
main() { int shmid; int semid; key_t key; int *child_shm, *parent_shm; union semun arg; int i; struct sembuf operations[1]; int status; int pid; /* Create the shared segment.& semaphore. */ if ((shmid = shmget(SHM_KEY, SHMSZ, IPC_CREAT | 0666)) < 0) { perror("shmget"); exit(1); } if ((semid = semget(SEM_KEY, 1, IPC_CREAT | 0666)) < 0) { perror("semget"); exit(1); } /* * Initialize the semaphore to value 1. The idea is multiple processes * do semop() of -1. So only one is allowed in critical section. * initialize the shm to 0. */ arg.val = 1; if (semctl(semid, 0, SETVAL, arg) < 0) { perror("semctl"); exit(1); } NP Lab Manual , RNEC page: 19
Page 1 and 2: IV YEAR B.Tech Network Programming
Page 3 and 4: o after call to fork o after both c
Page 5 and 6: WEEK 1: Aim: Implement the pipe usi
Page 7 and 8: Subject: NETWORK PROGRAMMING LAB Ye
Page 9 and 10: Output: [student@localhost ~]$ vi p
Page 11 and 12: Output: [student@localhost ~/khan]$
Page 13 and 14: } fclose(f); //closing file //creat
Page 17: Output: [student@localhost ~]$ cc m
Page 21 and 22: } for (i = 0; i < CHILD_INCREMENT_C
Page 23 and 24: if (*parent_shm == (CHILD_INCREMENT
Page 27 and 28: Output: [student@localhost ~]$ cc t
Page 29 and 30: Output: [student@localhost ~]$ ./ t
Page 31 and 32: } bzero(&servaddr, sizeof(servaddr)
Page 41 and 42: servAddr.sin_addr.s_addr = htonl(IN
Page 43 and 44: Output: [student@localhost ~]$ cc u
Page 45 and 46: *error = 0; return FD_ISSET(sd,&soc
Page 47 and 48: if(n
Page 51 and 52: printf("%s: from %s:UDP%u : %s \n"
Page 55 and 56: cliAddr.sin_family = AF_INET; cliAd
Page 59 and 60: if(rc
Page 63 and 64: if (select(sd+1,&socketReadSet,0,0,
Page 65 and 66: } (struct sockaddr *) &echoServAddr

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