void my_lock(int fd)
{
int oflag, i;
union semun arg;
struct semid_ds seminfo;
if (initflag == 0) {
oflag = IPC_CREAT | IPC_EXCL | SVSEM_MODE;
if ((semid = semget(Ftok(LOCK_PATH, 0), 1, oflag)) >= 0) {
arg.val = 1;
Semctl(semid, 0, SETVAL, arg);
} else if (errno == EEXIST) {
semid = Semget(Ftok(LOCK_PATH, 0), 1, SVSEM_MODE);
arg.buf = &seminfo;
for (i = 0; i < MAX_TRIES; i++) {
Semctl(semid, 0, IPC_STAT, arg);
if (arg.buf->sem_otime != 0)
goto init;
sleep(1);
}
err_quit("semget OK, but semaphore not initalized");
} else
err_sys("semget error");
init:
initflag = 1;
postop.sem_num = 0;
postop.sem_op = 1;
postop.sem_flg = SEM_UNDO;
waitop.semnum = 0;
waitop.semop = -1;
waitop.semflg = SEM_UNDO;
}
Semop(semid, &waitop, 1);
}
int main(int argc, char *argv[])
{
int readid, writeid;
key_t Rkey, Wkey;
Rkey = Ftok("/tmp/msg", 0);
Wkey = Ftok("/tmp/msg2", 0);
readid = Msgget(Rkey, 0644 | IPC_CREAT);
writeid = Msgget(Wkey, 0644 | IPC_CREAT);
server(readid, writeid);
exit(EXIT_FAILURE);
}
int
main(int argc, char **argv)
{
int c, flag, mqid;
long type;
ssize_t n;
struct msgbuf *buff;
type = flag = 0;
while ( (c = Getopt(argc, argv, "nt:")) != -1) {
switch (c) {
case 'n':
flag |= IPC_NOWAIT;
break;
case 't':
type = atol(optarg);
break;
}
}
if (optind != argc - 1)
err_quit("usage: msgrcv [ -n ] [ -t type ] <pathname>");
mqid = Msgget(Ftok(argv[optind], 0), MSG_R);
buff = Malloc(MAXMSG);
n = Msgrcv(mqid, buff, MAXMSG, type, flag);
printf("read %d bytes, type = %ld\n", n, buff->mtype);
exit(0);
}
int
main(int argc, char **argv)
{
int c, id, oflag;
char *ptr;
size_t length;
oflag = SVSHM_MODE | IPC_CREAT;
while ( (c = Getopt(argc, argv, "e")) != -1) {
switch (c) {
case 'e':
oflag |= IPC_EXCL;
break;
}
}
if (optind != argc - 2)
err_quit("usage: shmget [ -e ] <pathname> <length>");
length = atoi(argv[optind + 1]);
id = Shmget(Ftok(argv[optind], 0), length, oflag);
ptr = Shmat(id, NULL, 0);
printf("shm addr : %p\n", ptr);
exit(0);
}
int
main(int argc,char **argv)
{
int id;
if(argc!=2)
err_quit("ysage: shmrmid <pathname>");
id=Shmget(Ftok(argv[1],0),0,SVSHM_MODE);
Shmctl(id,IPC_RMID,NULL);
exit(0);
}
int main(int argc, char **argv)
{
int mqid;
if (argc != 2)
err_quit("Usage: rmid <pathname>");
mqid = Msgget(Ftok(argv[1], 0), 0);
Msgctl(mqid, IPC_RMID, NULL);
exit(0);
}
void
my_lock(int fd)
{
int oflag, i;
union semun arg;
struct semid_ds seminfo;
if (initflag == 0) {
oflag = IPC_CREAT | IPC_EXCL | SVSEM_MODE;
if ( (semid = semget(Ftok(LOCK_PATH, 0), 1, oflag)) >= 0) {
/* 4success, we're the first so initialize */
arg.val = 1;
Semctl(semid, 0, SETVAL, arg);
} else if (errno == EEXIST) {
/* 4someone else has created; make sure it's initialized */
semid = Semget(Ftok(LOCK_PATH, 0), 1, SVSEM_MODE);
arg.buf = &seminfo;
for (i = 0; i < MAX_TRIES; i++) {
Semctl(semid, 0, IPC_STAT, arg);
if (arg.buf->sem_otime != 0)
goto init;
Write(pipefd[1], "", 1); /* tell parent */
sleep(1);
}
err_quit("semget OK, but semaphore not initialized");
} else
err_sys("semget error");
init:
initflag = 1;
postop.sem_num = 0; /* and init the two semop() structures */
postop.sem_op = 1;
postop.sem_flg = SEM_UNDO;
waitop.sem_num = 0;
waitop.sem_op = -1;
waitop.sem_flg = SEM_UNDO;
}
Semop(semid, &waitop, 1); /* down by 1 */
}
int main(int argc, char **argv)
{
int i, id;
struct shmid_ds buff;
unsigned char *ptr;
if (argc != 2)
err_quit("Usage: write <pathname>");
id = Shmget(Ftok(argv[1], 0), 0, SVSHM_MODE);
ptr = Shmat(id, NULL, 0);
Shmctl(id, IPC_STAT, &buff);
for (i = 0; i < buff.shm_segsz; i++)
*ptr++ = i % 256;
exit(0);
}
int
main(int argc, char **argv)
{
int c, oflag, mqid;
oflag = SVMSG_MODE | IPC_CREAT;
while ( (c = Getopt(argc, argv, "e")) != -1) {
switch (c) {
case 'e':
oflag |= IPC_EXCL;
break;
}
}
if (optind != argc - 1)
err_quit("usage: msgcreate [ -e ] <pathname>");
mqid = Msgget(Ftok(argv[optind], 0), oflag);
exit(0);
}
int main(int argc, char **argv)
{
int mqid;
size_t len;
long type;
struct msgbuf *ptr;
if (argc != 4)
err_quit("Usage: msgsnd <pathname> <#bytes> <type>");
len = atoi(argv[2]);
type = atoi(argv[3]);
mqid = Msgget(Ftok(argv[1], 0), MSG_W);
ptr = (struct msgbuf *)Calloc(sizeof(long) + len, sizeof(char));
ptr->mtype = type;
Msgsnd(mqid, ptr, len, 0);
exit(0);
}
int main(int argc, char **argv)
{
int semid, nsems, i;
struct semid_ds seminfo;
unsigned short *ptr;
union semun arg;
if (argc < 2)
err_quit("Usage: setvalue <pathname> [ value ...]");
//first get the number of semaphore in the set
semid = Semget(Ftok(argv[1], 0), 0, 0);
arg.buf = &seminfo;
Semctl(semid, 0, IPC_STAT, arg);
nsems = arg.buf->sem_nsems;
//now get the values from the command line
ptr = Calloc(nsems, sizeof(unsigned short));
arg.array = ptr;
for (i = 0; i < nsems; i++)
ptr[i] = atoi(argv[i + 2]);
Semctl(semid, 0, SETALL, arg);
exit(0);
}