Enrico Fraccaroli (Galfurian)
66 lines
1.7 KiB
C
66 lines
1.7 KiB
C
//test
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#include "sys/unistd.h"
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#include "sys/errno.h"
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#include "sys/sem.h"
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#include "sys/ipc.h"
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#include "stdlib.h"
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#include "fcntl.h"
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#include "stdio.h"
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/*
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Testing IPC_NOWAIT flag.
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*/
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void semid_print(struct semid_ds *temp)
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{
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printf("pid, IPC_KEY, Semid, semop, change: %d, %d, %d, %d, %d\n", temp->sem_perm.uid, temp->sem_perm.key, temp->semid, temp->sem_otime, temp->sem_ctime);
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for (int i = 0; i < (temp->sem_nsems); i++) {
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printf("%d semaphore:\n", i + 1);
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printf("value: %d, pid %d, process waiting %d\n", temp->sems[i].sem_val, temp->sems[i].sem_pid, temp->sems[i].sem_zcnt);
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}
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}
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int main()
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{
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struct sembuf op[2];
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union semun arg;
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long ret, id;
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// Create the first semaphore.
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id = semget(IPC_PRIVATE, 1, IPC_CREAT | IPC_EXCL | S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP);
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printf("Id: %d\n", id);
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// Set the value of the semaphore in the structure.
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arg.val = 0;
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// Setting the semaphore value.
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printf("Set Value (%d): %d\n", id, arg.val);
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ret = semctl(id, 0, SETVAL, &arg);
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if (ret == -1) {
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perror("Failed to set value of semaphore.");
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return 1;
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}
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op[0].sem_num = 0;
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op[0].sem_op = 1;
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op[0].sem_flg = IPC_NOWAIT;
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op[1].sem_num = 0;
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op[1].sem_op = -2;
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op[1].sem_flg = IPC_NOWAIT;
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// Check the value of the semaphore.
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ret = semctl(id, 0, GETVAL, &arg);
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printf("Check Value before(%d): %d\n", id, ret);
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sleep(1);
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if ((ret = semop(id, op, 2)) == -1) {
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perror("Failed to perform semop");
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return 1;
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}
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// Check the value of the semaphore.
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ret = semctl(id, 0, GETVAL, &arg);
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printf("Check Value after(%d): %d\n", id, ret);
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return 0;
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} |