notBiji
119 lines
3.5 KiB
C
119 lines
3.5 KiB
C
//test
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#include "ipc/sem.h"
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#include "stdio.h"
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#include "ipc/ipc.h"
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#include "sys/errno.h"
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#include "stdlib.h"
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#include "sys/unistd.h"
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/*
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Testing Semaphores.
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This program creates a son and then performs a blocking operation on a semaphore. The son sleeps for
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five seconds and then it wakes up his father and then it deletes the semaphore.
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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->owner, temp->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;
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struct sembuf father[2];
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union semun arg;
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long ret, id;
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key_t key;
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// Checking if ftok works.
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key = ftok("/home/user/test7.txt", 5);
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printf("Key : %d\n", key);
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// Create the first semaphore.
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id = semget(2, 1, IPC_CREAT);
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printf("Id: %d\n", id);
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//long id2 = semget(IPC_PRIVATE, 1, IPC_CREAT);
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//long id2 = semget(2, 2, IPC_EXCL); //need to return -1 bc already exists
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//long id3 = semget(2, 2, 0); //need to return 3 (semid of the first)
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//long id4 = semget(100, 2, IPC_CREAT | IPC_EXCL); //need to return 101 (new semaphore)
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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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// Check if we successfully set 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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// Create child process.
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if (!fork()) {
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// Make the child process sleep.
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sleep(2);
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// Initialize the operation structure.
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op.sem_num = 0; // Operate on semaphore 0.
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op.sem_op = 1; // Increment value by 1.
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op.sem_flg = 0; // No flags.
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// This should allow the father process to decrement the semaphore by 2.
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// Perform the operation.
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semop(id, &op, 1);
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sleep(5);
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semop(id, &op, 1);
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// Remove the semaphore.
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//semctl(id, 0, IPC_RMID, NULL);
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// Exit with the child process.
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return 0;
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}
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// Initialize the operation structure.
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father[0].sem_num = 0; // Operate on semaphore 0.
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father[0].sem_op = -1; // Decrement value by 1.
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father[0].sem_flg = 0; // No flags.
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father[1].sem_num = 0; // Operate on semaphore 0.
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father[1].sem_op = -1; // Decrement value by 1.
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father[1].sem_flg = 0; // No flags.
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// We set the semaphore at the beginning at 1, and the child process will
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// increment the semaphore by 1, allowing us to decrement the semaphore by
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// 2.
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// Perform the operation.
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if (semop(id, father, 2) < 0) {
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printf("ERRORE\n");
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}
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// Check if we successfully set 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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/*if ((semid = semctl(id, 0, IPC_RMID, 0)) == -1){
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printf("%d\n", errno);
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}else{
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printf("found %d\n", semid);
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}*/
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//long id2 = semget(IPC_PRIVATE, 2, 0);
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//long id3 = semget(IPC_PRIVATE, 2, 0);
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//printf("id %d id2 %d id3 %d id4 %d\n", id, id2, id3, id4);
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/*if (i == -1){
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printf("Error with IPC_KEY\n");
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return -1;
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}*/
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return 0;
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} |