/***************************************************
* Creat : 2001. 02. 10 (programed by Cori-Young)
* Site: http://www.byoneself.co.kr
* Update :
***************************************************/
#include <stdio.h>
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/sem.h>
static int ask();
extern void exit();
extern void free();
extern char *malloc();
extern void perror();
static struct semid_ds semid_ds; /* status of semaphore set */
static char error_mesg1[] = "semop: Can't allocate space--1n";
static char error_mesg2[] = "semop: Can't allocate spaced--2";
main()
{
register int i; /* work area */
int nsops; /* number of operations to do */
int semid; /* semid of semaphore set */
struct sembuf *sops; /* ptr to operations to perform */
(void) fprintf(stderr, "All numeric input must follow C conventions:n");
(void) fprintf(stderr, "t0x... is interpreted as hexadecimal,n");
(void) fprintf(stderr, "t0... is interpreted as octal,n");
(void) fprintf(stderr, "totherwise, decimal.n");
/* Loop until the invoker doesn't want to do anymore. */
while (nsops = ask(&semid, &sops)) {
/* Initialize the array of operations to be performed.*/
for (i = 0; i < nsops; i++) {
(void) fprintf(stderr,"nEnter values for operation %d of %d.n", i + 1, nsops);
(void) fprintf(stderr, "sem_num(valid values are 0 <= sem_num < %d): ",semid_ds.sem_nsems);
(void) scanf("%hi", &sops[i].sem_num);
(void) fprintf(stderr, "sem_op: ");
(void) scanf("%hi", &sops[i].sem_op);
(void) fprintf(stderr, "Expected flags in sem_flg are:n");
(void) fprintf(stderr, "tIPC_NOWAIT =t%#6.6on", IPC_NOWAIT);
(void) fprintf(stderr, "tSEM_UNDO =t%#6.6on", SEM_UNDO);
(void) fprintf(stderr, "sem_flg: ");
(void) scanf("%hi", &sops[i].sem_flg);
}
/* Recap the call to be made. */
(void) fprintf(stderr, "nsemop: Calling semop(%d, &sops, %d) with:", semid, nsops);
for (i = 0; i < nsops; i++)
{
(void) fprintf(stderr, "nsops[%d].sem_num = %d, ", i, sops[i].sem_num);
(void) fprintf(stderr, "sem_op = %d, ", sops[i].sem_op);
(void) fprintf(stderr, "sem_flg = %#on", sops[i].sem_flg);
}
/* Make the semop() call and report the results. */
if ((i = semop(semid, sops, nsops)) == -1) {
perror("semop: semop failed");
}
else {
(void) fprintf(stderr, "semop: semop returned %dn", i);
}
}
}
static ask(semidp, sopsp)
int *semidp; /* pointer to semid (used only the first time) */
struct sembuf **sopsp;
{
static union semun arg; /* argument to semctl */
int i; /* work area */
static int nsops = 0; /* size of currently allocated sembuf array */
static int semid = -1; /* semid supplied by user */
static struct sembuf *sops; /* pointer to allocated array */
if (semid < 0) {
/* First call; get semid from user and the current state of the semaphore set. */
(void) fprintf(stderr, "Enter semid of the semaphore set you want to use: ");
(void) scanf("%i", &semid);
*semidp = semid;
arg.buf = &semid_ds;
if (semctl(semid, 0, IPC_STAT, arg) == -1)
{
perror("semop: semctl(IPC_STAT) failed");
/* Note that if semctl fails, semid_ds remains filled with zeros, so later test for number of semaphores will be zero. */
(void) fprintf(stderr, "Before and after values are not printed.n");
}
else {
if ((arg.array = (ushort *)malloc((unsigned)(sizeof(ushort) * semid_ds.sem_nsems))) == NULL) {
(void) fprintf(stderr, error_mesg1, semid_ds.sem_nsems);
exit(1);
}
}
}
/* Print current semaphore values. */
if (semid_ds.sem_nsems) {
(void) fprintf(stderr, "There are %d semaphores in the set.n", semid_ds.sem_nsems);
if (semctl(semid, 0, GETALL, arg) == -1) {
perror("semop: semctl(GETALL) failed");
}
else {
(void) fprintf(stderr, "Current semaphore values are:");
for (i = 0; i < semid_ds.sem_nsems; (void) fprintf(stderr, " %d", arg.array[i++]));
(void) fprintf(stderr, "n");
}
}
/* Find out how many operations are going to be done in the next call and allocate enough space to do it. */
(void) fprintf(stderr, "How many semaphore operations do you want %sn", "on the next call to semop()?");
(void) fprintf(stderr, "Enter 0 or control-D to quit: ");
i = 0;
if (scanf("%i", &i) == EOF || i == 0)
exit(0);
if (i > nsops) {
if (nsops)
free((char *)sops);
nsops = i;
if ((sops = (struct sembuf *)malloc((unsigned)(nsops * sizeof(struct sembuf)))) == NULL) {
(void) fprintf(stderr, error_mesg2, nsops);
exit(2);
}
}
*sopsp = sops;
return (i);
} |
|
