/***************************************************
* 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>
#include <time.h>
union semun {
int val;
struct semid_ds *buf;
ushort *array;
};
struct semid_ds semid_ds;
static void do_semctl();
static void do_stat();
extern char *malloc();
extern void exit();
extern void perror();
char warning_message[] = "If you remove read permission for yourself, this program will fail frequently!";
main()
{
union semun arg;
int cmd, i,semid, semnum;
(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");
(void) fprintf(stderr, "Enter semid value: ");
(void) scanf("%i", &semid);
(void) fprintf(stderr, "Valid semctl cmd values are:n");
(void) fprintf(stderr, "tGETALL = %dn", GETALL);
(void) fprintf(stderr, "tGETNCNT = %dn", GETNCNT);
(void) fprintf(stderr, "tGETPID = %dn", GETPID);
(void) fprintf(stderr, "tGETVAL = %dn", GETVAL);
(void) fprintf(stderr, "tGETZCNT = %dn", GETZCNT);
(void) fprintf(stderr, "tIPC_RMID = %dn", IPC_RMID);
(void) fprintf(stderr, "tIPC_SET = %dn", IPC_SET);
(void) fprintf(stderr, "tIPC_STAT = %dn", IPC_STAT);
(void) fprintf(stderr, "tSETALL = %dn", SETALL);
(void) fprintf(stderr, "tSETVAL = %dn", SETVAL);
(void) fprintf(stderr, "nEnter cmd: ");
(void) scanf("%i", &cmd);
/* Do some setup operations needed by multiple commands. */
switch (cmd) {
case GETVAL:
case SETVAL:
case GETNCNT:
case GETZCNT:
/* Get the semaphore number for these commands. */
(void) fprintf(stderr, "nEnter semnum value: ");
(void) scanf("%i", &semnum);
break;
case GETALL:
case SETALL:
/* Allocate a buffer for the semaphore values. */
(void) fprintf(stderr, "Get number of semaphores in the set.n");
arg.buf = &semid_ds;
do_semctl(semid, 0, IPC_STAT, arg);
if (arg.array = (ushort *)malloc((unsigned)(semid_ds.sem_nsems * sizeof(ushort)))) {
/* Break out if you got what you needed. */
break;
}
(void) fprintf(stderr, "semctl: unable to allocate space for %d valuesn", semid_ds.sem_nsems);
exit(2);
}
/* Get the rest of the arguments needed for the specified command. */
switch (cmd) {
case SETVAL:
/* Set value of one semaphore. */
(void) fprintf(stderr, "nEnter semaphore value: ");
(void) scanf("%i", &arg.val);
do_semctl(semid, semnum, SETVAL, arg);
/* Fall through to verify the result. */
(void) fprintf(stderr, "Do semctl GETVAL command to verify results.n");
case GETVAL:
/* Get value of one semaphore. */
arg.val = 0;
do_semctl(semid, semnum, GETVAL, arg);
break;
case GETPID:
/* Get PID of last process to successfully complete a
semctl(SETVAL), semctl(SETALL), or semop() on the semaphore. */
arg.val = 0;
do_semctl(semid, 0, GETPID, arg);
break;
case GETNCNT:
/* Get number of processes waiting for semaphore value to increase. */
arg.val = 0;
do_semctl(semid, semnum, GETNCNT, arg);
break;
case GETZCNT:
/* Get number of processes waiting for semaphore value to become zero. */
arg.val = 0;
do_semctl(semid, semnum, GETZCNT, arg);
break;
case SETALL:
/* Set the values of all semaphores in the set. */
(void) fprintf(stderr, "There are %d semaphores in the set.n", semid_ds.sem_nsems);
(void) fprintf(stderr, "Enter semaphore values:n");
for (i = 0; i < semid_ds.sem_nsems; i++) {
(void) fprintf(stderr, "Semaphore %d: ", i);
(void) scanf("%hi", &arg.array[i]);
}
do_semctl(semid, 0, SETALL, arg);
/* Fall through to verify the results. */
(void) fprintf(stderr, "Do semctl GETALL command to verify results.n");
case GETALL:
/* Get and print the values of all semaphores in the set.*/
do_semctl(semid, 0, GETALL, arg);
(void) fprintf(stderr,"The values of the %d semaphores are:n",semid_ds.sem_nsems);
for (i = 0; i < semid_ds.sem_nsems; i++)
(void) fprintf(stderr, "%d ", arg.array[i]);
(void) fprintf(stderr, "n");
break;
case IPC_SET: /* Modify mode and/or ownership. */
arg.buf = &semid_ds;
do_semctl(semid, 0, IPC_STAT, arg);
(void) fprintf(stderr, "Status before IPC_SET:n");
do_stat();
(void) fprintf(stderr, "Enter sem_perm.uid value: ");
(void) scanf("%hi", &semid_ds.sem_perm.uid);
(void) fprintf(stderr, "Enter sem_perm.gid value: ");
(void) scanf("%hi", &semid_ds.sem_perm.gid);
(void) fprintf(stderr, "%sn", warning_message);
(void) fprintf(stderr, "Enter sem_perm.mode value: ");
(void) scanf("%hi", &semid_ds.sem_perm.mode);
do_semctl(semid, 0, IPC_SET, arg);
/* Fall through to verify changes. */
(void) fprintf(stderr, "Status after IPC_SET:n");
case IPC_STAT:
/* Get and print current status. */
arg.buf = &semid_ds;
do_semctl(semid, 0, IPC_STAT, arg);
do_stat();
break;
case IPC_RMID:
/* Remove the semaphore set. */
arg.val = 0;
do_semctl(semid, 0, IPC_RMID, arg);
break;
default:
/* Pass unknown command to semctl. */
arg.val = 0;
do_semctl(semid, 0, cmd, arg);
break;
}
exit(0);
}
static void do_semctl(semid, semnum, cmd, arg)
union semun arg;
int cmd, semid, semnum;
{
register int i; /* work area */
(void) fprintf(stderr, "nsemctl: Calling semctl:%d, %d, %dn", semid, semnum, cmd);
switch (cmd) {
case GETALL:
(void) fprintf(stderr, "arg.array = %#x)n", arg.array);
break;
case IPC_STAT:
case IPC_SET:
(void) fprintf(stderr, "arg.buf = %#x)n", arg.buf);
break;
case SETALL:
(void) fprintf(stderr, "arg.array = [", arg.buf);
for (i = 0;i < semid_ds.sem_nsems;) {
(void) fprintf(stderr, "%d", arg.array[i++]);
if (i < semid_ds.sem_nsems)
(void) fprintf(stderr, ", ");
}
(void) fprintf(stderr, "])n");
break;
case SETVAL:
default:
(void) fprintf(stderr, "arg.val = %d)n", arg.val);
break;
}
i = semctl(semid, semnum, cmd, arg);
if (i == -1){
perror("semctl: semctl failed");
exit(1);
}
(void) fprintf(stderr, "semctl: semctl returned %dn", i);
return;
}
static void do_stat()
{
(void) fprintf(stderr, "sem_perm.uid = %dn", semid_ds.sem_perm.uid);
(void) fprintf(stderr, "sem_perm.gid = %dn", semid_ds.sem_perm.gid);
(void) fprintf(stderr, "sem_perm.cuid = %dn", semid_ds.sem_perm.cuid);
(void) fprintf(stderr, "sem_perm.cgid = %dn", semid_ds.sem_perm.cgid);
(void) fprintf(stderr, "sem_perm.mode = %#o, ",semid_ds.sem_perm.mode);
(void) fprintf(stderr, "access permissions = %#on",semid_ds.sem_perm.mode & 0777);
(void) fprintf(stderr, "sem_nsems = %dn",semid_ds.sem_nsems);
(void) fprintf(stderr, "sem_otime = %s", semid_ds.sem_otime ?ctime(&semid_ds.sem_otime) : "Not Setn");
(void) fprintf(stderr, "sem_ctime = %s",ctime(&semid_ds.sem_ctime));
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