2

TMP/Practice/04.10/semget.c

@@ -0,0 +1,52 @@
+       #include <stdio.h>
+       #include <stdlib.h>
+       #include <sys/ipc.h>
+       #include <sys/sem.h>
+       #include <unistd.h>
+
+       static void
+       usage(const char *pname)
+       {
+           fprintf(stderr, "Usage: %s [-cx] pathname proj-id num-sems\n",
+                   pname);
+           fprintf(stderr, "    -c           Use IPC_CREAT flag\n");
+           fprintf(stderr, "    -x           Use IPC_EXCL flag\n");
+           exit(EXIT_FAILURE);
+       }
+
+       int
+       main(int argc, char *argv[])
+       {
+           int    semid, nsems, flags, opt;
+           key_t  key;
+
+           flags = 0;
+           while ((opt = getopt(argc, argv, "cx")) != -1) {
+               switch (opt) {
+               case 'c': flags |= IPC_CREAT;   break;
+               case 'x': flags |= IPC_EXCL;    break;
+               default:  usage(argv[0]);
+               }
+           }
+
+           if (argc != optind + 3)
+               usage(argv[0]);
+
+           key = ftok(argv[optind], argv[optind + 1][0]);
+           if (key == -1) {
+               perror("ftok");
+               exit(EXIT_FAILURE);
+           }
+
+           nsems = atoi(argv[optind + 2]);
+
+           semid = semget(key, nsems, flags | 0600);
+           if (semid == -1) {
+               perror("semget");
+               exit(EXIT_FAILURE);
+           }
+
+           printf("ID = %d\n", semid);
+
+           exit(EXIT_SUCCESS);
+       }