65 lines
1.9 KiB
C++
65 lines
1.9 KiB
C++
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//
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// Created by Cigerxwin Chaker on 05.11.19.
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//
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#include <iostream>
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#include <sys/_types.h>
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#include <sys/ipc.h>
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#include <sys/shm.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <sys/stat.h>
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//#include "sharedMemory.h" /* header is important for the shmID. name could be different. maybe not needed cause: (shmget(memory_access_key, NULL, 0)) */
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#include <sys/sem.h>
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#include <unistd.h>
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int initSemaphore (void) {
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/* Testen, ob das Semaphor bereits existiert */
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semId = semget (semKey, 0, IPC_PRIVATE);
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if (semId < 0) {
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/* ... existiert noch nicht, also anlegen */
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/* Alle Zugriffsrechte der Dateikreierungsmaske */
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/* erlauben */
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umask(0);
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semId = semget (semKey, 1, IPC_CREAT | IPC_EXCL | PERM);
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if (semId < 0) {
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return -1;
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}
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/* Semaphor mit 1 initialisieren */
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if (semctl (semId, 0, SETVAL, (int) 1) == -1)
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return -1;
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}
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return 1;
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}
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int semaphoreOperation (int op) {
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semaphore.sem_op = op;
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semaphore.sem_flg = SEM_UNDO;
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if( semop (semId, &semaphore, 1) == -1) {
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perror(" semop ");
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exit (EXIT_FAILURE);
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}
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return 1;
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}
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void writeToShm(char* text, int size) {
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int shmId = shmget(memoryAccessKey, NULL, 0);
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if(shmId < 0 ) {
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exit(EXIT_FAILURE);
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/* we could return -1, not sure if it will be useful to continue after there is no shm allocated for any reason*/
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} else {
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char *shm_pointer = (char *) shmat(shmId, NULL, 0);
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semaphore_operation(LOCK);
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memcpy(shm_pointer, text, size);
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semaphore_operation(UNLOCK);
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}
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}
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char* getShmPointer() {
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int shmId = shmget(memoryAccessKey, NULL, 0);
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if(shmId < 0) {
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exit(EXIT_FAILURE);
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/* we could return -1, not sure if it will be useful to continue after there is no shm allocated for any reason*/
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} else {
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return (char *) shmat(shmId, NULL, 0);
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}
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}
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