115 lines
2.3 KiB
C
115 lines
2.3 KiB
C
/* Mecanismes de communication entre processus - IPC */
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/* Ecriture dans une zone de mémoire partajée (shared memory - shm ) */
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// VERSION AVEC SEMAPHORE
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#include <stdlib.h>
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#include <stdio.h>
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#include <sys/ipc.h>
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#include <sys/shm.h>
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#include <sys/types.h>
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#define SHMEM_SIZE 0xff
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#define SHMEM_RIGHTS 0x01ff
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void erreur(char *mess);
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int main (int argc, char ** argv) {
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long i , k , temp;
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long * ptz ;
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int p1 , p2, p3, p4;
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int ipc_key, ipc_result ;
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int mutex; // id du semaphore
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if (argc<2)
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exit(1) ;
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ipc_key = atoi(argv[1]) ;
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ipc_result = shmget(ipc_key, 0 , 0) ; // ouverture mémoire partagée
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ptz = (long *) shmat(ipc_result, 0, SHMEM_RIGHTS) ; // attachement mémoire partagée
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// creation du semaphore mutex
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if((mutex = creat_sem(ipc_key+1,1)) == -1)
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erreur("erreur creation semaphore");
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if ((p1 = fork()) == 0) {
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for(i=0;i<10;i++) {
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P(mutex); //__________________________
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temp = * ptz;
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temp++;
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sleep( rand() % 2 ); // attente aléatoire
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*ptz = temp; ;
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V(mutex); //________________________________
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//(*ptz) ++ ;
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}
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exit(0) ;
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}
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if ((p2 = fork()) == 0) {
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for(i=0;i<10;i++) {
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P(mutex); //__________________________
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temp = * ptz;
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temp++;
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sleep( rand() % 2 ); // attente aléatoire
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*ptz = temp;
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V(mutex); //________________________________
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}
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exit(0) ;
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}
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if ((p3 = fork()) == 0) {
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for(i=0;i<10;i++) {
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P(mutex); //__________________________
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temp = * ptz;
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temp++;
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sleep( rand() % 2 ); // attente aléatoire
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*ptz = temp;
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V(mutex); //________________________________
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//(*ptz) ++ ;
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}
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exit(0) ;
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}
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if ((p4 = fork()) == 0) {
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for(i=0;i<10;i++) {
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P(mutex); //__________________________
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temp = * ptz;
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temp++;
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sleep( rand() % 2 ); // attente aléatoire
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*ptz = temp; ;
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//(*ptz) ++ ;
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V(mutex); //________________________________
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}
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exit(0) ;
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}
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// while(wait(0) != -1); si le père attend que tous ses fils soient terminés
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// suppression du semaphore
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//del_sem(mutex);
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printf("\n Arret processus pid = %d compteur ( %d ) \n\n", getpid(), *ptz) ;
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exit(0) ;
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}
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